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Sample records for based combined cycle

  1. The Strutjet Rocket Based Combined Cycle Engine

    Science.gov (United States)

    Siebenhaar, A.; Bulman, M. J.; Bonnar, D. K.

    1998-01-01

    The multi stage chemical rocket has been established over many years as the propulsion System for space transportation vehicles, while, at the same time, there is increasing concern about its continued affordability and rather involved reusability. Two broad approaches to addressing this overall launch cost problem consist in one, the further development of the rocket motor, and two, the use of airbreathing propulsion to the maximum extent possible as a complement to the limited use of a conventional rocket. In both cases, a single-stage-to-orbit (SSTO) vehicle is considered a desirable goal. However, neither the "all-rocket" nor the "all-airbreathing" approach seems realizable and workable in practice without appreciable advances in materials and manufacturing. An affordable system must be reusable with minimal refurbishing on-ground, and large mean time between overhauls, and thus with high margins in design. It has been suggested that one may use different engine cycles, some rocket and others airbreathing, in a combination over a flight trajectory, but this approach does not lead to a converged solution with thrust-to-mass, specific impulse, and other performance and operational characteristics that can be obtained in the different engines. The reason is this type of engine is simply a combination of different engines with no commonality of gas flowpath or components, and therefore tends to have the deficiencies of each of the combined engines. A further development in this approach is a truly combined cycle that incorporates a series of cycles for different modes of propulsion along a flight path with multiple use of a set of components and an essentially single gas flowpath through the engine. This integrated approach is based on realizing the benefits of both a rocket engine and airbreathing engine in various combinations by a systematic functional integration of components in an engine class usually referred to as a rocket-based combined cycle (RBCC) engine

  2. Overview of the Turbine Based Combined Cycle Discipline

    Science.gov (United States)

    Thomas, Scott R.; Walker, James F.; Pittman, James L.

    2009-01-01

    The NASA Fundamental Aeronautics Hypersonics project is focused on technologies for combined cycle, airbreathing propulsions systems to enable reusable launch systems for access to space. Turbine Based Combined Cycle (TBCC) propulsion systems offer specific impulse (Isp) improvements over rocket-based propulsion systems in the subsonic takeoff and return mission segments and offer improved safety. The potential to realize more aircraft-like operations with expanded launch site capability and reduced system maintenance are additional benefits. The most critical TBCC enabling technologies as identified in the National Aeronautics Institute (NAI) study were: 1) mode transition from the low speed propulsion system to the high speed propulsion system, 2) high Mach turbine engine development, 3) transonic aero-propulsion performance, 4) low-Mach-number dual-mode scramjet operation, 5) innovative 3-D flowpath concepts and 6) innovative turbine based combined cycle integration. To address several of these key TBCC challenges, NASA s Hypersonics project (TBCC Discipline) initiated an experimental mode transition task that includes an analytic research endeavor to assess the state-of-the-art of propulsion system performance and design codes. This initiative includes inlet fluid and turbine performance codes and engineering-level algorithms. This effort has been focused on the Combined Cycle Engine Large-Scale Inlet Mode Transition Experiment (CCE LIMX) which is a fully integrated TBCC propulsion system with flow path sizing consistent with previous NASA and DoD proposed Hypersonic experimental flight test plans. This experiment is being tested in the NASA-GRC 10 x 10 Supersonic Wind Tunnel (SWT) Facility. The goal of this activity is to address key hypersonic combined-cycle-engine issues: (1) dual integrated inlet operability and performance issues unstart constraints, distortion constraints, bleed requirements, controls, and operability margins, (2) mode

  3. Parametric Study Conducted of Rocket- Based, Combined-Cycle Nozzles

    Science.gov (United States)

    Steffen, Christopher J., Jr.; Smith, Timothy D.

    1998-01-01

    Having reached the end of the 20th century, our society is quite familiar with the many benefits of recycling and reusing the products of civilization. The high-technology world of aerospace vehicle design is no exception. Because of the many potential economic benefits of reusable launch vehicles, NASA is aggressively pursuing this technology on several fronts. One of the most promising technologies receiving renewed attention is Rocket-Based, Combined-Cycle (RBCC) propulsion. This propulsion method combines many of the efficiencies of high-performance jet aircraft with the power and high-altitude capability of rocket engines. The goal of the present work at the NASA Lewis Research Center is to further understand the complex fluid physics within RBCC engines that govern system performance. This work is being performed in support of NASA's Advanced Reusable Technologies program. A robust RBCC engine design optimization demands further investigation of the subsystem performance of the engine's complex propulsion cycles. The RBCC propulsion system under consideration at Lewis is defined by four modes of operation in a singlestage- to-orbit configuration. In the first mode, the engine functions as a rocket-driven ejector. When the rocket engine is switched off, subsonic combustion (mode 2) is present in the ramjet mode. As the vehicle continues to accelerate, supersonic combustion (mode 3) occurs in the ramjet mode. Finally, as the edge of the atmosphere is approached and the engine inlet is closed off, the rocket is reignited and the final accent to orbit is undertaken in an all-rocket mode (mode 4). The performance of this fourth and final mode is the subject of this present study. Performance is being monitored in terms of the amount of thrust generated from a given amount of propellant.

  4. Thermodynamic assessment of a wind turbine based combined cycle

    International Nuclear Information System (INIS)

    Rabbani, M.; Dincer, I.; Naterer, G.F.

    2012-01-01

    Combined cycles use the exhaust gases released from a Gas Turbine (GT). Approximately 30–40% of the turbine shaft work is typically used to drive the Compressor. The present study analyzes a system that couples a Wind Turbine (WT) with a combined cycle. It demonstrates how a WT can be used to supply power to the Compressor in the GT cycle and pump fluid through a reheat Rankine cycle, in order to increase the overall power output. Three different configurations are discussed, namely high penetration, low penetration and wind power addition. In the case of a low electricity demand and high penetration configuration, extra wind power is used to compress air which can then be used in the low penetration configuration. During a high load demand, all the wind power is used to drive the pump and compressor and if required additional compressed air is supplied by a storage unit. The analysis shows that increasing the combustion temperature reduces the critical velocity and mass flow rate. Increases in wind speed reduce both energy and exergy efficiency of the overall system. -- Highlights: ► This study analyzes a system that couples a wind turbine with a combined power generation cycle. ► Surplus wind power is used to compress air, which is then stored and used at a later time. ► Increasing the pressure ratio will reduce the work ratio between the Rankine and Brayton cycles. ► A higher combustion temperature will increase the net work output, as well as the system energy and exergy efficiencies.

  5. Numerical simulation of divergent rocket-based-combined-cycle performances under the flight condition of Mach 3

    Science.gov (United States)

    Cui, Peng; Xu, WanWu; Li, Qinglian

    2018-01-01

    Currently, the upper operating limit of the turbine engine is Mach 2+, and the lower limit of the dual-mode scramjet is Mach 4. Therefore no single power systems can operate within the range between Mach 2 + and Mach 4. By using ejector rockets, Rocket-based-combined-cycle can work well in the above scope. As the key component of Rocket-based-combined-cycle, the ejector rocket has significant influence on Rocket-based-combined-cycle performance. Research on the influence of rocket parameters on Rocket-based-combined-cycle in the speed range of Mach 2 + to Mach 4 is scarce. In the present study, influences of Mach number and total pressure of the ejector rocket on Rocket-based-combined-cycle were analyzed numerically. Due to the significant effects of the flight conditions and the Rocket-based-combined-cycle configuration on Rocket-based-combined-cycle performances, flight altitude, flight Mach number, and divergence ratio were also considered. The simulation results indicate that matching lower altitude with higher flight Mach numbers can increase Rocket-based-combined-cycle thrust. For another thing, with an increase of the divergent ratio, the effect of the divergent configuration will strengthen and there is a limit on the divergent ratio. When the divergent ratio is greater than the limit, the effect of divergent configuration will gradually exceed that of combustion on supersonic flows. Further increases in the divergent ratio will decrease Rocket-based-combined-cycle thrust.

  6. Unsteady flow characteristic analysis of turbine based combined cycle (TBCC inlet mode transition

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2015-09-01

    Full Text Available A turbine based combined cycle (TBCC propulsion system uses a turbine-based engine to accelerate the vehicle from takeoff to the mode transition flight condition, at which point, the propulsion system performs a “mode transition” from the turbine to ramjet engine. Smooth inlet mode transition is accomplished when flow is diverted from one flowpath to the other, without experiencing unstart or buzz. The smooth inlet mode transition is a complex unsteady process and it is one of the enabling technologies for combined cycle engine to become a functional reality. In order to unveil the unsteady process of inlet mode transition, the research of over/under TBCC inlet mode transition was conducted through a numerical simulation. It shows that during the mode transition the terminal shock oscillates in the inlet. During the process of inlet mode transition mass flow rate and Mach number of turbojet flowpath reduce with oscillation. While in ramjet flowpath the flow field is non-uniform at the beginning of inlet mode transition. The speed of mode transition and the operation states of the turbojet and ramjet engines will affect the motion of terminal shock. The result obtained in present paper can help us realize the unsteady flow characteristic during the mode transition and provide some suggestions for TBCC inlet mode transition based on the smooth transition of thrust.

  7. Optimal production of power in a combined cycle from manure based biogas

    International Nuclear Information System (INIS)

    León, Erick; Martín, Mariano

    2016-01-01

    Highlights: • Manure based biogas is a promising renewable source to add value to waste. • Mathematical optimization is used to design a process including gas and steam turbines. • Two schemes for steam production and the effect of animal headcount are compared. • Direct use of flue gas for steam production is recommended. • Digestate economics is key for a competitive price of electricity. - Abstract: In this work, the production of power using a combined cycle gas turbine/steam turbine, which operates with biogas as fuel, is evaluated. The process begins with the production of biogas from pig and/or cattle slurry manure(s) using anaerobic digestion. Afterwards, the gas is cleaned up to remove humidity, hydrogen sulfide, carbon dioxide and ammonia. The cleaned gas (biomethane) is then used in a Brayton cycle (gas turbine) to produce energy. The flue gas that exits the Brayton cycle is typically at high temperature and it is further utilized to produce steam that generates power in a regenerative Rankine cycle (steam turbine). Two alternative steam production schemes are evaluated: either splitting the flue gas to have high temperature gas for the reheating step of the steam or sequential heating up. The model is formulated as a Mixer Integer Nonlinear Programming (MINLP) solved in GAMS® for the optimal production of power. For a typical production capacity of manure in farms, 2.6 MW are produced. The investment for the plant turns out to be 26 M€ and the production cost of the electricity is 0.35 €/kW h before including the credit from the conditioned digestate, that could be sold as fertilizer. The electricity cost goes down to 0.15 €/kW h considering a reasonable credit from the digestate, whose composition depends on the feedstock processed in the facility.

  8. Biomass Gasification Combined Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Judith A. Kieffer

    2000-07-01

    Gasification combined cycle continues to represent an important defining technology area for the forest products industry. The ''Forest Products Gasification Initiative'', organized under the Industry's Agenda 2020 technology vision and supported by the DOE ''Industries of the Future'' program, is well positioned to guide these technologies to commercial success within a five-to ten-year timeframe given supportive federal budgets and public policy. Commercial success will result in significant environmental and renewable energy goals that are shared by the Industry and the Nation. The Battelle/FERCO LIVG technology, which is the technology of choice for the application reported here, remains of high interest due to characteristics that make it well suited for integration with the infrastructure of a pulp production facility. The capital cost, operating economics and long-term demonstration of this technology area key input to future economically sustainable projects and must be verified by the 200 BDT/day demonstration facility currently operating in Burlington, Vermont. The New Bern application that was the initial objective of this project is not currently economically viable and will not be implemented at this time due to several changes at and around the mill which have occurred since the inception of the project in 1995. The analysis shows that for this technology, and likely other gasification technologies as well, the first few installations will require unique circumstances, or supportive public policies, or both to attract host sites and investors.

  9. Control Activity in Support of NASA Turbine Based Combined Cycle (TBCC) Research

    Science.gov (United States)

    Stueber, Thomas J.; Vrnak, Daniel R.; Le, Dzu K.; Ouzts, Peter J.

    2010-01-01

    Control research for a Turbine Based Combined Cycle (TBCC) propulsion system is the current focus of the Hypersonic Guidance, Navigation, and Control (GN&C) discipline team. The ongoing work at the NASA Glenn Research Center (GRC) supports the Hypersonic GN&C effort in developing tools to aid the design of control algorithms to manage a TBCC airbreathing propulsion system during a critical operating period. The critical operating period being addressed in this paper is the span when the propulsion system transitions from one cycle to another, referred to as mode transition. One such tool, that is a basic need for control system design activities, is computational models (hereto forth referred to as models) of the propulsion system. The models of interest for designing and testing controllers are Control Development Models (CDMs) and Control Validation Models (CVMs). CDMs and CVMs are needed for each of the following propulsion system elements: inlet, turbine engine, ram/scram dual-mode combustor, and nozzle. This paper presents an overall architecture for a TBCC propulsion system model that includes all of the propulsion system elements. Efforts are under way, focusing on one of the propulsion system elements, to develop CDMs and CVMs for a TBCC propulsion system inlet. The TBCC inlet aerodynamic design being modeled is that of the Combined-Cycle Engine (CCE) Testbed. The CCE Testbed is a large-scale model of an aerodynamic design that was verified in a small-scale screening experiment. The modeling approach includes employing existing state-of-the-art simulation codes, developing new dynamic simulations, and performing system identification experiments on the hardware in the NASA GRC 10 by10-Foot Supersonic Wind Tunnel. The developed CDMs and CVMs will be available for control studies prior to hardware buildup. The system identification experiments on the CCE Testbed will characterize the necessary dynamics to be represented in CDMs for control design. These

  10. Thermodynamic analysis of a Kalina-based combined cooling and power cycle driven by low-grade heat source

    International Nuclear Information System (INIS)

    Cao, Liyan; Wang, Jiangfeng; Wang, Hongyang; Zhao, Pan; Dai, Yiping

    2017-01-01

    Highlights: • A Kalina-based combined cooling and power cycle is proposed to recover low-grade heat source. • The effects of several parameters on cycle performance are examined. • An optimization is conducted by GA to obtain optimum performance. - Abstract: This paper investigates a Kalina-based combined cooling and power (CCP) cycle driven by low-grade heat source. The proposed cycle consists of a Kalina cycle and an absorption refrigeration cycle. By establishing the mathematical model, numerical simulation is conducted and parametric analysis is performed to examine the effects of five key parameters on the thermodynamic performances of Kalina-based CCP cycle. A performance optimization is conducted by genetic algorithm to obtain the optimum exergy efficiency. According to parametric analysis, an optimum expander inlet pressure can be achieved; exergy efficiency increases with expander inlet pressure and concentration of ammonia-water basic solution, but exergy efficiency decreases when terminal temperature difference of high-temperature recuperator and low-temperature recuperator increases. Refrigeration exergy increases with expander inlet pressure and decreases as expander inlet temperature and concentration of ammonia-water basic solution rise. However, the refrigeration exergy keeps constant as the terminal temperature difference of high-temperature recuperator and low-temperature recuperator vary. Furthermore, the optimized Kalina-based CCP cycle is compared with a separate generation system which is also optimized. The optimization results show that the exergy efficiency and net power output of Kalina-based CCP are higher than those of separate generation system.

  11. Combustion oscillation study in a kerosene fueled rocket-based combined-cycle engine combustor

    Science.gov (United States)

    Huang, Zhi-Wei; He, Guo-Qiang; Qin, Fei; Xue, Rui; Wei, Xiang-Geng; Shi, Lei

    2016-12-01

    This study reports the combustion oscillation features in a three-dimensional (3D) rocket-based combined-cycle (RBCC) engine combustor under flight Mach number (Mflight) 3.0 conditions both experimentally and numerically. Experiment is performed on a direct-connect ground test facility, which measures the wall pressure along the flow-path. High-speed imaging of the flame luminosity and schlieren is carried out at exit of the primary rocket. Compressible reactive large eddy simulation (LES) with reduced chemical kinetics of a surrogate model for kerosene is performed to further understand the combustion oscillation mechanisms in the combustor. LES results are validated with experimental data by the time-averaged and root mean square (RMS) pressure values, and show acceptable agreement. Effects of the primary rocket jet on pressure oscillation in the combustor are analyzed. Relation of the high speed rocket jet oscillation, which is thought to among the most probable sources of combustion oscillation, with the RBCC combustor is recognized. Results reveal that the unsteady over-expanded rocket jet has significant impacts on the combustion oscillation feature of the RBCC combustor, which is different from a thermo-acoustics type oscillation. The rocket jet/air inflow physical interactions under different rocket jet expansion degrees are experimentally studied.

  12. An optimization method for gas refrigeration cycle based on the combination of both thermodynamics and entransy theory

    International Nuclear Information System (INIS)

    Chen, Qun; Xu, Yun-Chao; Hao, Jun-Hong

    2014-01-01

    Highlights: • An optimization method for practical thermodynamic cycle is developed. • The entransy-based heat transfer analysis and thermodynamic analysis are combined. • Theoretical relation between system requirements and design parameters is derived. • The optimization problem can be converted into conditional extremum problem. • The proposed method provides several useful optimization criteria. - Abstract: A thermodynamic cycle usually consists of heat transfer processes in heat exchangers and heat-work conversion processes in compressors, expanders and/or turbines. This paper presents a new optimization method for effective improvement of thermodynamic cycle performance with the combination of entransy theory and thermodynamics. The heat transfer processes in a gas refrigeration cycle are analyzed by entransy theory and the heat-work conversion processes are analyzed by thermodynamics. The combination of these two analysis yields a mathematical relation directly connecting system requirements, e.g. cooling capacity rate and power consumption rate, with design parameters, e.g. heat transfer area of each heat exchanger and heat capacity rate of each working fluid, without introducing any intermediate variable. Based on this relation together with the conditional extremum method, we theoretically derive an optimization equation group. Simultaneously solving this equation group offers the optimal structural and operating parameters for every single gas refrigeration cycle and furthermore provides several useful optimization criteria for all the cycles. Finally, a practical gas refrigeration cycle is taken as an example to show the application and validity of the newly proposed optimization method

  13. HTR-Based Power Plants’ Performance Analysis Applied on Conventional Combined Cycles

    Directory of Open Access Journals (Sweden)

    José Carbia Carril

    2015-01-01

    Full Text Available In high temperature reactors including gas cooled fast reactors and gas turbine modular helium reactors (GT-MHR specifically designed to operate as power plant heat sources, efficiency enhancement at effective cost under safe conditions can be achieved. Mentioned improvements concern the implementation of two cycle structures: (a, a stand alone Brayton operating with helium and a stand alone Rankine cycle (RC with regeneration, operating with carbon dioxide at ultrasupercritical pressure as working fluid (WF, where condensation is carried out at quasicritical conditions, and (b, a combined cycle (CC, in which the topping closed Brayton cycle (CBC operates with helium as WF, while the bottoming RC is operated with one of the following WFs: carbon dioxide, xenon, ethane, ammonia, or water. In both cases, an intermediate heat exchanger (IHE is proposed to provide thermal energy to the closed Brayton or to the Rankine cycles. The results of the case study show that the thermal efficiency, through the use of a CC, is slightly improved (from 45.79% for BC and from 50.17% for RC to 53.63 for the proposed CC with He-H2O operating under safety standards.

  14. Optimum gas turbine cycle for combined cycle power plant

    International Nuclear Information System (INIS)

    Polyzakis, A.L.; Koroneos, C.; Xydis, G.

    2008-01-01

    The gas turbine based power plant is characterized by its relatively low capital cost compared with the steam power plant. It has environmental advantages and short construction lead time. However, conventional industrial engines have lower efficiencies, especially at part load. One of the technologies adopted nowadays for efficiency improvement is the 'combined cycle'. The combined cycle technology is now well established and offers superior efficiency to any of the competing gas turbine based systems that are likely to be available in the medium term for large scale power generation applications. This paper has as objective the optimization of a combined cycle power plant describing and comparing four different gas turbine cycles: simple cycle, intercooled cycle, reheated cycle and intercooled and reheated cycle. The proposed combined cycle plant would produce 300 MW of power (200 MW from the gas turbine and 100 MW from the steam turbine). The results showed that the reheated gas turbine is the most desirable overall, mainly because of its high turbine exhaust gas temperature and resulting high thermal efficiency of the bottoming steam cycle. The optimal gas turbine (GT) cycle will lead to a more efficient combined cycle power plant (CCPP), and this will result in great savings. The initial approach adopted is to investigate independently the four theoretically possible configurations of the gas plant. On the basis of combining these with a single pressure Rankine cycle, the optimum gas scheme is found. Once the gas turbine is selected, the next step is to investigate the impact of the steam cycle design and parameters on the overall performance of the plant, in order to choose the combined cycle offering the best fit with the objectives of the work as depicted above. Each alterative cycle was studied, aiming to find the best option from the standpoint of overall efficiency, installation and operational costs, maintainability and reliability for a combined power

  15. Modelling and optimization of combined cycle power plant based on exergoeconomic and environmental analyses

    International Nuclear Information System (INIS)

    Ganjehkaviri, A.; Mohd Jaafar, M.N.; Ahmadi, P.; Barzegaravval, H.

    2014-01-01

    This research paper presents a study on a comprehensive thermodynamic modelling of a combined cycle power plant (CCPP). The effects of economic strategies and design parameters on the plant optimization are also studied. Exergoeconomic analysis is conducted in order to determine the cost of electricity and cost of exergy destruction. In addition, a comprehensive optimization study is performed to determine the optimal design parameters of the power plant. Next, the effects of economic parameters variations on the sustainability, carbon dioxide emission and fuel consumption of the plant are investigated and are presented for a typical combined cycle power plant. Therefore, the changes in economic parameters caused the balance between cash flows and fix costs of the plant changes at optimum point. Moreover, economic strategies greatly limited the maximum reasonable carbon emission and fuel consumption reduction. The results showed that by using the optimum values, the exergy efficiency increases for about 6%, while CO 2 emission decreases by 5.63%. However, the variation in the cost was less than 1% due to the fact that a cost constraint was implemented. In addition, the sensitivity analysis for the optimization study was curtailed to be carried out; therefore, the optimization process and results to two important parameters are presented and discussed.

  16. Evaluation of a combined cycle based on an HCCI (Homogenous Charge Compression Ignition) engine heat recovery employing two organic Rankine cycles

    International Nuclear Information System (INIS)

    Khaljani, M.; Saray, R. Khoshbakhti; Bahlouli, K.

    2016-01-01

    In this work, a combined power cycle which includes a HCCI (Homogenous Charge Compression Ignition) engine and two ORCs (Organic Rankine Cycles) is introduced. In the proposed cycle, the waste heats from the engine cooling water and exhaust gases are utilized to drive the ORCs. A parametric study is conducted to show the effects of decision parameters on the performance and on the total cost rate of cycle. Results of the parametric study reveal that increasing the pinch point temperature difference of evaporator and temperature of the condenser leads to reduction in both exergy efficiency and total cost rate of the bottoming cycle. There is a specific evaporator temperature where exergy efficiency is improved, but the total cost rate of the bottoming cycle is maximized. Also, a multi-objective optimization strategy is performed to achieve the best system design parameters from both thermodynamic and economic aspects. The exergy efficiency and the total cost rate of the system have been considered as objective functions. Optimization results indicate that the exergy efficiency of the cycle increases from 44.96% for the base case to 46.02%. Also, approximately1.3% reduction in the cost criteria is achieved. Results of the multi-objective optimization justify the results obtained through the parametric study and demonstrate that the design parameters of both ORCs have conflict effect on the objective functions. - Highlights: • Two Organic Rankine bottoming cycles are coupled with an HCCI Engine. • Exergetic and Exergo-economic analysis of the bottoming cycle are reported. • The system is optimized using multi-objective genetic algorithm. • Objective functions are exergy efficiency and total cost rate of the system. • The exergy efficiency of the cycle increases from 44.96% to 46.02%.

  17. Performance analysis of a bio-gasification based combined cycle power plant employing indirectly heated humid air turbine

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S., E-mail: sankha.deepp@gmail.com; Mondal, P., E-mail: mondal.pradip87@gmail.com; Ghosh, S., E-mail: sudipghosh.becollege@gmail.com [Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah – 711103, West Bengal (India)

    2016-07-12

    Rapid depletion of fossil fuel has forced mankind to look into alternative fuel resources. In this context, biomass based power generation employing gas turbine appears to be a popular choice. Bio-gasification based combined cycle provides a feasible solution as far as grid-independent power generation is concerned for rural electrification projects. Indirectly heated gas turbine cycles are promising alternatives as they avoid downstream gas cleaning systems. Advanced thermodynamic cycles have become an interesting area of study to improve plant efficiency. Water injected system is one of the most attractive options in this field of applications. This paper presents a theoretical model of a biomass gasification based combined cycle that employs an indirectly heated humid air turbine (HAT) in the topping cycle. Maximum overall electrical efficiency is found to be around 41%. Gas turbine specific air consumption by mass is minimum when pressure ratio is 6. The study reveals that, incorporation of the humidification process helps to improve the overall performance of the plant.

  18. Highlights from a Mach 4 Experimental Demonstration of Inlet Mode Transition for Turbine-Based Combined Cycle Hypersonic Propulsion

    Science.gov (United States)

    Foster, Lancert E.; Saunders, John D., Jr.; Sanders, Bobby W.; Weir, Lois J.

    2012-01-01

    NASA is focused on technologies for combined cycle, air-breathing propulsion systems to enable reusable launch systems for access to space. Turbine Based Combined Cycle (TBCC) propulsion systems offer specific impulse (Isp) improvements over rocket-based propulsion systems in the subsonic takeoff and return mission segments along with improved safety. Among the most critical TBCC enabling technologies are: 1) mode transition from the low speed propulsion system to the high speed propulsion system, 2) high Mach turbine engine development and 3) innovative turbine based combined cycle integration. To address these challenges, NASA initiated an experimental mode transition task including analytical methods to assess the state-of-the-art of propulsion system performance and design codes. One effort has been the Combined-Cycle Engine Large Scale Inlet Mode Transition Experiment (CCE-LIMX) which is a fully integrated TBCC propulsion system with flowpath sizing consistent with previous NASA and DoD proposed Hypersonic experimental flight test plans. This experiment was tested in the NASA GRC 10 by 10-Foot Supersonic Wind Tunnel (SWT) Facility. The goal of this activity is to address key hypersonic combined-cycle engine issues including: (1) dual integrated inlet operability and performance issues-unstart constraints, distortion constraints, bleed requirements, and controls, (2) mode-transition sequence elements caused by switching between the turbine and the ramjet/scramjet flowpaths (imposed variable geometry requirements), and (3) turbine engine transients (and associated time scales) during transition. Testing of the initial inlet and dynamic characterization phases were completed and smooth mode transition was demonstrated. A database focused on a Mach 4 transition speed with limited off-design elements was developed and will serve to guide future TBCC system studies and to validate higher level analyses.

  19. Diagnosis of Combined Cycle Power Plant Based on Thermoeconomic Analysis: A Computer Simulation Study

    Directory of Open Access Journals (Sweden)

    Hoo-Suk Oh

    2017-11-01

    Full Text Available In this study, diagnosis of a 300-MW combined cycle power plant under faulty conditions was performed using a thermoeconomic method called modified productive structure analysis. The malfunction and dysfunction, unit cost of irreversibility and lost cost flow rate for each component were calculated for the cases of pre-fixed malfunction and the reference conditions. A commercial simulating software, GateCycleTM (version 6.1.2, was used to estimate the thermodynamic properties under faulty conditions. The relative malfunction (RMF and the relative difference in the lost cost flow rate between real operation and reference conditions (RDLC were found to be effective indicators for the identification of faulty components. Simulation results revealed that 0.5% degradation in the isentropic efficiency of air compressor, 2% in gas turbine, 2% in steam turbine and 2% degradation in energy loss in heat exchangers can be identified. Multi-fault scenarios that can be detected by the indicators were also considered. Additional lost exergy due to these types of faulty components, that can be detected by RMF or RDLC, is less than 5% of the exergy lost in the components in the normal condition.

  20. Combining agent-based modeling and life cycle assessment for the evaluation of mobility policies.

    Science.gov (United States)

    Florent, Querini; Enrico, Benetto

    2015-02-03

    This article presents agent-based modeling (ABM) as a novel approach for consequential life cycle assessment (C-LCA) of large scale policies, more specifically mobility-related policies. The approach is validated at the Luxembourgish level (as a first case study). The agent-based model simulates the car market (sales, use, and dismantling) of the population of users in the period 2013-2020, following the implementation of different mobility policies and available electric vehicles. The resulting changes in the car fleet composition as well as the hourly uses of the vehicles are then used to derive consistent LCA results, representing the consequences of the policies. Policies will have significant environmental consequences: when using ReCiPe2008, we observe a decrease of global warming, fossil depletion, acidification, ozone depletion, and photochemical ozone formation and an increase of metal depletion, ionizing radiations, marine eutrophication, and particulate matter formation. The study clearly shows that the extrapolation of LCA results for the circulating fleet at national scale following the introduction of the policies from the LCAs of single vehicles by simple up-scaling (using hypothetical deployment scenarios) would be flawed. The inventory has to be directly conducted at full scale and to this aim, ABM is indeed a promising approach, as it allows identifying and quantifying emerging effects while modeling the Life Cycle Inventory of vehicles at microscale through the concept of agents.

  1. Uncertainty analysis of integrated gasification combined cycle systems based on Frame 7H versus 7F gas turbines.

    Science.gov (United States)

    Zhu, Yunhua; Frey, H Christopher

    2006-12-01

    Integrated gasification combined cycle (IGCC) technology is a promising alternative for clean generation of power and coproduction of chemicals from coal and other feedstocks. Advanced concepts for IGCC systems that incorporate state-of-the-art gas turbine systems, however, are not commercially demonstrated. Therefore, there is uncertainty regarding the future commercial-scale performance, emissions, and cost of such technologies. The Frame 7F gas turbine represents current state-of-practice, whereas the Frame 7H is the most recently introduced advanced commercial gas turbine. The objective of this study was to evaluate the risks and potential payoffs of IGCC technology based on different gas turbine combined cycle designs. Models of entrained-flow gasifier-based IGCC systems with Frame 7F (IGCC-7F) and 7H gas turbine combined cycles (IGCC-7H) were developed in ASPEN Plus. An uncertainty analysis was conducted. Gasifier carbon conversion and project cost uncertainty are identified as the most important uncertain inputs with respect to system performance and cost. The uncertainties in the difference of the efficiencies and costs for the two systems are characterized. Despite uncertainty, the IGCC-7H system is robustly preferred to the IGCC-7F system. Advances in gas turbine design will improve the performance, emissions, and cost of IGCC systems. The implications of this study for decision-making regarding technology selection, research planning, and plant operation are discussed.

  2. A Technology Pathway for Airbreathing, Combined-Cycle, Horizontal Space Launch Through SR-71 Based Trajectory Modeling

    Science.gov (United States)

    Kloesel, Kurt J.; Ratnayake, Nalin A.; Clark, Casie M.

    2011-01-01

    Access to space is in the early stages of commercialization. Private enterprises, mainly under direct or indirect subsidy by the government, have been making headway into the LEO launch systems infrastructure, of small-weight-class payloads of approximately 1000 lbs. These moderate gains have emboldened the launch industry and they are poised to move into the middle-weight class (roughly 5000 lbs). These commercially successful systems are based on relatively straightforward LOX-RP, two-stage, bi-propellant rocket technology developed by the government 40 years ago, accompanied by many technology improvements. In this paper we examine a known generic LOX-RP system with the focus on the booster stage (1st stage). The booster stage is then compared to modeled Rocket-Based and Turbine-Based Combined Cycle booster stages. The air-breathing propulsion stages are based on/or extrapolated from known performance parameters of ground tested RBCC (the Marquardt Ejector Ramjet) and TBCC (the SR-71/J-58 engine) data. Validated engine models using GECAT and SCCREAM are coupled with trajectory optimization and analysis in POST-II to explore viable launch scenarios using hypothetical aerospaceplane platform obeying the aerodynamic model of the SR-71. Finally, and assessment is made of the requisite research technology advances necessary for successful commercial and government adoption of combined-cycle engine systems for space access.

  3. Analysis of an electricity–cooling cogeneration system based on RC–ARS combined cycle aboard ship

    International Nuclear Information System (INIS)

    Liang, Youcai; Shu, Gequn; Tian, Hua; Liang, Xingyu; Wei, Haiqiao; Liu, Lina

    2013-01-01

    Highlights: • A novel electricity–cooling cogeneration system was used to recover waste heat aboard ships. • Performance of such RC–ARS system was investigated theoretically. • Optimal exergy output can be obtained when the vaporization pressure of RC is 300 kPa. • The exergy efficiency of cogeneration system is 5–12% higher than that of basic Rankine cycle only. - Abstract: In this paper, an electricity–cooling cogeneration system based on Rankine–absorption refrigeration combined cycle is proposed to recover the waste heat of the engine coolant and exhaust gas to generate electricity and cooling onboard ships. Water is selected as the working fluid of the Rankine cycle (RC), and a binary solution of ammonia–water is used as the working fluid of the absorption refrigeration cycle. The working fluid of RC is preheated by the engine coolant and then evaporated and superheated by the exhaust gas. The absorption cycle is powered by the heat of steam at the turbine outlet. Electricity output, cooling capacity, total exergy output, primary energy ratio (PER) and exergy efficiency are chosen as the objective functions. Results show that the amount of additional cooling output is up to 18 MW. Exergy output reaches the maximum 4.65 MW at the vaporization pressure of 300 kPa. The study reveals that the electricity–cooling cogeneration system has improved the exergy efficiency significantly: 5–12% increase compared with the basic Rankine cycle only. Primary energy ratio (PER) decreases as the vaporization pressure increases, varying from 0.47 to 0.40

  4. A study for the optimal operating conditions of the gas turbine based combined cycle cogeneration power plant

    International Nuclear Information System (INIS)

    Cho, Young Bin; Sohn, Jeong Lak; Ro, Sung Tack

    2004-01-01

    The purpose of this study is to show the existence of optimal operation conditions for minimum fuel consumption of the gas turbine based combined cycle cogeneration power plant. Optimal operational condition means the optimal distribution of the power generated by each gas turbine and the heat generated by each HRSG. Total fuel consumption is calculated by the sum of the fuels for gas turbines and supplementary boiler. Fuel consumption is calculated by numerical methods of energy equations which contain the power generated from gas and steam turbines, the heat generated by HRSG and the heat extracted from high pressure steam turbine

  5. Reuse fo a Cold War Surveillance Drone to Flight Test a NASA Rocket Based Combined Cycle Engine

    Science.gov (United States)

    Brown, T. M.; Smith, Norm

    1999-01-01

    Plans for and early feasibility investigations into the modification of a Lockheed D21B drone to flight test the DRACO Rocket Based Combined Cycle (RBCC) engine are discussed. Modifications include the addition of oxidizer tanks, modern avionics systems, actuators, and a vehicle recovery system. Current study results indicate that the D21B is a suitable candidate for this application and will allow demonstrations of all DRACO engine operating modes at Mach numbers between 0.8 and 4.0. Higher Mach numbers may be achieved with more extensive modification. Possible project risks include low speed stability and control, and recovery techniques.

  6. Exergoeconomic analysis with reliability and availability considerations of a nuclear energy-based combined cycle power plant

    International Nuclear Information System (INIS)

    Zare, V.

    2016-01-01

    The reliability and availability considerations are introduced in the exergoeconomic investigation of a combined cycle power plant in which an organic Rankine cycle is employed to recover the waste heat from a GT-MHR (Gas Turbine Modular Helium Reactor) power plant. The SPECO (specific exergy costing) theory is employed to investigate the exergoeconomic performance of the system and assess the specific cost of the output power. For the reliability analysis, however, the SSM (state-space method) along with the probabilistic analysis of Markov processes is employed. After conducting a parametric analysis, the performance of the cycle is optimized with respect to the specific cost of output power, with and without reliability considerations. The effects of the system failure and repair rates are examined on the cost of power and availability of the combined cycle by the sensitivity analysis. The optimization results show that, the specific cost of output power for the combined cycle is around 12% lower than that for the stand alone GT-MHR. However, availability of the combined cycle is lower than that of the GT-MHR as the former has more components and a complicated system. - Highlights: • Specific exergy costing approach is applied to the combined GT-MHR/ORC plant. • Reliability and availability considerations are taken into account. • A reduction of 12% in specific cost of power for the combined cycle is achieved. • The reliability inclusion in the analysis increases the cost of power by about 4%.

  7. Thermodynamic analysis of a combined-cycle solar thermal power plant with manganese oxide-based thermochemical energy storage

    Science.gov (United States)

    Lei, Qi; Bader, Roman; Kreider, Peter; Lovegrove, Keith; Lipiński, Wojciech

    2017-11-01

    We explore the thermodynamic efficiency of a solar-driven combined cycle power system with manganese oxide-based thermochemical energy storage system. Manganese oxide particles are reduced during the day in an oxygen-lean atmosphere obtained with a fluidized-bed reactor at temperatures in the range of 750-1600°C using concentrated solar energy. Reduced hot particles are stored and re-oxidized during night-time to achieve continuous power plant operation. The steady-state mass and energy conservation equations are solved for all system components to calculate the thermodynamic properties and mass flow rates at all state points in the system, taking into account component irreversibilities. The net power block and overall solar-to-electric energy conversion efficiencies, and the required storage volumes for solids and gases in the storage system are predicted. Preliminary results for a system with 100 MW nominal solar power input at a solar concentration ratio of 3000, designed for constant round-the-clock operation with 8 hours of on-sun and 16 hours of off-sun operation and with manganese oxide particles cycled between 750 and 1600°C yield a net power block efficiency of 60.0% and an overall energy conversion efficiency of 41.3%. Required storage tank sizes for the solids are estimated to be approx. 5-6 times smaller than those of state-of-the-art molten salt systems.

  8. Thermodynamic analysis of a combined-cycle solar thermal power plant with manganese oxide-based thermochemical energy storage

    Directory of Open Access Journals (Sweden)

    Lei Qi

    2017-01-01

    Full Text Available We explore the thermodynamic efficiency of a solar-driven combined cycle power system with manganese oxide-based thermochemical energy storage system. Manganese oxide particles are reduced during the day in an oxygen-lean atmosphere obtained with a fluidized-bed reactor at temperatures in the range of 750–1600°C using concentrated solar energy. Reduced hot particles are stored and re-oxidized during night-time to achieve continuous power plant operation. The steady-state mass and energy conservation equations are solved for all system components to calculate the thermodynamic properties and mass flow rates at all state points in the system, taking into account component irreversibilities. The net power block and overall solar-to-electric energy conversion efficiencies, and the required storage volumes for solids and gases in the storage system are predicted. Preliminary results for a system with 100 MW nominal solar power input at a solar concentration ratio of 3000, designed for constant round-the-clock operation with 8 hours of on-sun and 16 hours of off-sun operation and with manganese oxide particles cycled between 750 and 1600°C yield a net power block efficiency of 60.0% and an overall energy conversion efficiency of 41.3%. Required storage tank sizes for the solids are estimated to be approx. 5–6 times smaller than those of state-of-the-art molten salt systems.

  9. New waste heat district heating system with combined heat and power based on absorption heat exchange cycle in China

    International Nuclear Information System (INIS)

    Sun Fangtian; Fu Lin; Zhang Shigang; Sun Jian

    2012-01-01

    A new waste heat district heating system with combined heat and power based on absorption heat exchange cycle (DHAC) was developed to increase the heating capacity of combined heat and power (CHP) through waste heat recovery, and enhance heat transmission capacity of the existing primary side district heating network through decreasing return water temperature by new type absorption heat exchanger (AHE). The DHAC system and a conventional district heating system based on CHP (CDH) were analyzed in terms of both thermodynamics and economics. Compared to CDH, the DHAC increased heating capacity by 31% and increased heat transmission capacity of the existing primary side district heating network by 75%. The results showed that the exergetic efficiency of DHAC was 10.41% higher and the product exergy monetary cost was 36.6¥/GJ less than a CHD. DHAC is an effective way to increase thermal utilization factor of CHP, and to reduce district heating cost. - Highlights: ► Absorption heat pumps are used to recover waste heat in CHP. ► Absorption heat exchanger can reduce exergy loss in the heat transfer process. ► New waste heat heating system (DHAC) can increase heating capacity of CHP by 31%. ► DHAC can enhance heat transmission capacity of the primary pipe network by 75%. ► DHAC system has the higher exergetic efficiency and the better economic benefit.

  10. Performance of an Axisymmetric Rocket Based Combined Cycle Engine During Rocket Only Operation Using Linear Regression Analysis

    Science.gov (United States)

    Smith, Timothy D.; Steffen, Christopher J., Jr.; Yungster, Shaye; Keller, Dennis J.

    1998-01-01

    The all rocket mode of operation is shown to be a critical factor in the overall performance of a rocket based combined cycle (RBCC) vehicle. An axisymmetric RBCC engine was used to determine specific impulse efficiency values based upon both full flow and gas generator configurations. Design of experiments methodology was used to construct a test matrix and multiple linear regression analysis was used to build parametric models. The main parameters investigated in this study were: rocket chamber pressure, rocket exit area ratio, injected secondary flow, mixer-ejector inlet area, mixer-ejector area ratio, and mixer-ejector length-to-inlet diameter ratio. A perfect gas computational fluid dynamics analysis, using both the Spalart-Allmaras and k-omega turbulence models, was performed with the NPARC code to obtain values of vacuum specific impulse. Results from the multiple linear regression analysis showed that for both the full flow and gas generator configurations increasing mixer-ejector area ratio and rocket area ratio increase performance, while increasing mixer-ejector inlet area ratio and mixer-ejector length-to-diameter ratio decrease performance. Increasing injected secondary flow increased performance for the gas generator analysis, but was not statistically significant for the full flow analysis. Chamber pressure was found to be not statistically significant.

  11. Nutritional Combined Greenhouse Gas Life Cycle Analysis for Incorporating Canadian Yellow Pea into Cereal-Based Food Products

    Directory of Open Access Journals (Sweden)

    Abhishek Chaudhary

    2018-04-01

    Full Text Available Incorporating low cost pulses, such as yellow peas, that are rich in nutrients and low in fertilizer requirements, into daily food items, can improve the nutritional and sustainability profile of national diets. This paper systematically characterized the effect of using Canadian grown whole yellow pea and refined wheat flours on nutritional density and carbon footprint in cereal-based food products. Canada-specific production data and the levels of 27 macro- and micronutrients were used to calculate the carbon footprint and nutrient balance score (NBS, respectively, for traditional and reformulated pan bread, breakfast cereal, and pasta. Results showed that partial replacement of refined wheat flour with yellow pea flour increased the NBS of pan bread, breakfast cereal, and pasta by 11%, 70%, and 18%, and decreased the life cycle carbon footprint (kg CO2 eq/kg by 4%, 11%, and 13%, respectively. The cultivation stage of wheat and yellow peas, and the electricity used during the manufacturing stage of food production, were the hotspots in the life cycle. The nutritional and greenhouse gas (GHG data were combined as the nutrition carbon footprint score (NCFS (NBS/g CO2 per serving, a novel indicator that reflects product-level nutritional quality per unit environmental impact. Results showed that yellow pea flour increased the NCFS by 15% for pan bread, 90% for breakfast cereal, and 35% for pasta. The results and framework of this study are relevant for food industry, consumers, as well as global and national policy-makers evaluating the effect of dietary change and food reformulation on nutritional and climate change targets.

  12. Computational Fluid Dynamics (CFD) Simulation of Hypersonic Turbine-Based Combined-Cycle (TBCC) Inlet Mode Transition

    Science.gov (United States)

    Slater, John W.; Saunders, John D.

    2010-01-01

    Methods of computational fluid dynamics were applied to simulate the aerodynamics within the turbine flowpath of a turbine-based combined-cycle propulsion system during inlet mode transition at Mach 4. Inlet mode transition involved the rotation of a splitter cowl to close the turbine flowpath to allow the full operation of a parallel dual-mode ramjet/scramjet flowpath. Steady-state simulations were performed at splitter cowl positions of 0deg, -2deg, -4deg, and -5.7deg, at which the turbine flowpath was closed half way. The simulations satisfied one objective of providing a greater understanding of the flow during inlet mode transition. Comparisons of the simulation results with wind-tunnel test data addressed another objective of assessing the applicability of the simulation methods for simulating inlet mode transition. The simulations showed that inlet mode transition could occur in a stable manner and that accurate modeling of the interactions among the shock waves, boundary layers, and porous bleed regions was critical for evaluating the inlet static and total pressures, bleed flow rates, and bleed plenum pressures. The simulations compared well with some of the wind-tunnel data, but uncertainties in both the windtunnel data and simulations prevented a formal evaluation of the accuracy of the simulation methods.

  13. Ascent phase trajectory optimization for vehicle with multi-combined cycle engine based on improved particle swarm optimization

    Science.gov (United States)

    Zhou, Hongyu; Wang, Xiaogang; Bai, Yuliang; Cui, Naigang

    2017-11-01

    An improved particle swarm optimization (IPSO) algorithm is proposed to optimize the ascent phase trajectory for vehicle with multi-combined cycle engine. Aerodynamic and thrust models are formulated in couple with flying states and environment. Conventional PSO has advantages in solving complicated optimization problems but has troubles in constraints handling and premature convergence preventing. To handle constraints, a modification in the fitness function of infeasible particles is executed based on the constraints violation and a comparation is executed to choose the better particle according to the fitness. To prevent premature, a diminishing number of particles are chosen to be mutated on the velocity by random times and directions. The ascent trajectory is divided into sub-phases according to engine modes. Different constraints, control parameters and engine models are considered in each sub-phase. Though the proposed algorithm is straightforward in comprehension and implementation, the numerical examples demonstrate that the algorithm has better performance than other PSO variants. In comparation with the commercial software GPOPS, the performance index of IPSO is almost the same as GPOPS but the results are less oscillating and dependent on initial values.

  14. Parametric based thermo-environmental and exergoeconomic analyses of a combined cycle power plant with regression analysis and optimization

    International Nuclear Information System (INIS)

    Memon, Abdul Ghafoor; Memon, Rizwan Ahmed; Harijan, Khanji; Uqaili, Mohammad Aslam

    2015-01-01

    Highlights: • Thermo-environmental and exergoeconomic models of a combined cycle power plant are defined. • Effects of various operating parameters on performance, CO 2 emissions and costs are deliberated. • Multiple polynomial regression models are developed. • For various operating conditions, optimal operating parameters are determined. - Abstract: A combined cycle power plant is analyzed through thermo-environmental, exergoeconomic and statistical methods. The plant is first modeled and parametrically studied to deliberate the effects of various operating parameters on the thermo-environmental quantities, like net power output, energy efficiency, exergy efficiency and CO 2 emissions. These quantities are then correlated with operating parameters through multiple polynomial regression analysis. Moreover, exergoeconomic analysis is performed to look into the impact of operating parameters on fuel cost, capital cost and exergy destruction cost. The optimal operating parameters are then determined using the Nelder-Mead simplex method by defining two objective functions, namely exergy efficiency (maximized) and total cost (minimized). According to the parametric analysis, the operating parameters impart significant effects on the performance and cost rates. The regression models are appearing to be a good estimator of the response variables since appended with satisfactory R 2 values. The optimization results exhibit that the exergy efficiency is increased and cost rates are decreased by selecting the best trade-off values at different power output conditions

  15. Multi-objective optimization of a combined steam-organic Rankine cycle based on exergy and exergo-economic analysis for waste heat recovery application

    International Nuclear Information System (INIS)

    Nazari, Navid; Heidarnejad, Parisa; Porkhial, Soheil

    2016-01-01

    Highlights: • Exergo-economic optimization of combined steam-organic cycle is performed. • Genetic algorithm is used to perform multi-objective optimization. • Total product cost rate and exergy efficiency were selected as the objective function. • Three different organic fluids (R124, R152a andR134a) were chosen to monitor the system performance. • A parametric study is done using three different decision variables. - Abstract: In this paper, a combined steam-organic Rankine cycle is proposed to recover the waste heat of a gas turbine. Proposed combined system includes a subcritical steam Rankine cycle that is coupled with a transcritical organic Rankine cycle. Three different organic fluids such as R124, R152a, and R134a are selected to monitor the thermodynamic and exergo-economic performance of the system. Results show that maximum exergy efficiency and minimum total product cost rate of a studied system for the base case condition are 57.62% and 396.7 ($/h) for the combined cycle with R124 and R152a, respectively. Also, a parametric study is performed to investigate the effects of key parameters including steam turbine inlet pressure, organic turbine inlet pressure, organic preheater pinch temperature and organic condensation temperature on exergetic efficiency and total product cost rate of the system. Finally, the Genetic algorithm is employed to conduct a multi-objective optimization of the system with two objective functions including exergy efficiency and total product cost rate. The results of optimization revealed that combined cycle with R152a has the best performance from thermodynamic and exergo-economic viewpoint among analyzed fluids.

  16. Corrosion behavior of Haynes registered 230 registered nickel-based super-alloys for integrated coal gasification combined cycle syngas plants. A plant exposure study

    International Nuclear Information System (INIS)

    Lee, Sungkyu; Lee, Jieun; Kang, Suk-Hwan; Lee, Seung-Jong; Yun, Yongseung; Kim, Min Jung

    2015-01-01

    The corrosion behavior of commercially available Haynes registered 230 registered nickel-based alloy samples was investigated by exposure to coal-gasifying integrated coal gasification combined cycle pilot plant facilities affiliated with the Institute for Advanced Engineering (2.005 MPa and 160-300 C). The morphological and microstructural analyses of the exposed samples were conducted using scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis on the external surface of the recovered corrosion test samples to obtain information of the corrosion scale. These analyses based on the pre- and post-exposure corrosion test samples combined with thermodynamic Ellingham-Pourbaix stability diagrams provided preliminary insight into the mechanism of the observed corrosion behavior prevailing in the piping materials that connected the particulate removal unit and water scrubber of the integrated coal gasification combined cycle pilot plant. Uniform material wastage was observed after 46 hours of operation, and a preliminary corrosion mechanism was suggested: the observed material waste and corrosion behavior of the Haynes registered 230 registered nickel-based alloy samples cut off from the coal syngas integrated coal gasification combined cycle plant were explained by the formation of discontinuous (complex) oxide phases and subsequent chlorine-induced active oxidation under the predominantly reducing environment encountered. This contribution continues the already published studies of the Fe-Ni-Cr-Co alloy Haynes registered 556 registered .

  17. Steam plant: Steam turbines for combined cycles

    Science.gov (United States)

    Schrieken, J.

    Parameters affecting steam turbines design are discussed and it is concluded that steam turbines for combined cycles are suitable for: powers between 1 and 250 MW; driving a generator, via a gearbox if necessary; drive through of powers which can be up to three times their own power; and ground level installation with up, side, or axial exhaust for condensing turbine applications. Parameters affecting the steam turbine performance are discussed: inlet conditions and flows, sliding inlet conditions, reheat cycles, fired and unfired heat recovery steam generators, cogeneration systems, and combined cycle for process steam supply. Aerodynamic design aspects of steam turbines for combined cycles are discussed. It is concluded that steam turbines for combined cycles have a large range of special requirements. Some typical aspects are: large exhaust annular areas and special exhaust arrangements for condensing steam turbines, drive through of the power of the gas turbines, high influence on the total cycle performance optimization, and a wide variety of extraction systems for cogeneration.

  18. Sensitivity analysis of exergy destruction in a real combined cycle power plant based on advanced exergy method

    International Nuclear Information System (INIS)

    Boyaghchi, Fateme Ahmadi; Molaie, Hanieh

    2015-01-01

    Highlights: • The advanced exergy destruction components of a real CCPP are calculated. • The TIT and r c variation are investigated on exergy destruction parts of the cycle. • The TIT and r c growth increase the improvement potential in the most of components. • The TIT and r c growth decrease the unavoidable part in some components. - Abstract: The advanced exergy analysis extends engineering knowledge beyond the respective conventional methods by improving the design and operation of energy conversion systems. In advanced exergy analysis, the exergy destruction is splitting into endogenous/exogenous and avoidable/unavoidable parts. In this study, an advanced exergy analysis of a real combined cycle power plant (CCPP) with supplementary firing is done. The endogenous/exogenous irreversibilities of each component as well as their combination with avoidable/unavoidable irreversibilities are determined. A parametric study is presented discussing the sensitivity of various performance indicators to the turbine inlet temperature (TIT), and compressor pressure ratio (r c ). It is observed that the thermal and exergy efficiencies increase when TIT and r c rise. Results show that combustion chamber (CC) concentrates most of the exergy destruction (more than 62%), dominantly in unavoidable endogenous form which is decreased by 11.89% and 13.12% while the avoidable endogenous exergy destruction increase and is multiplied by the factors of 1.3 and 8.6 with increasing TIT and r c , respectively. In addition, TIT growth strongly increases the endogenous avoidable exergy destruction in high pressure superheater (HP.SUP), CC and low pressure evaporator (LP.EVAP). It, also, increases the exogenous avoidable exergy destruction of HP.SUP and low pressure steam turbine (LP.ST) and leads to the high decrement in the endogenous exergy destruction of the preheater (PRE) by about 98.8%. Furthermore, r c growth extremely rises the endogenous avoidable exergy destruction of gas

  19. Maximisation of Combined Cycle Power Plant Efficiency

    Directory of Open Access Journals (Sweden)

    Janusz Kotowicz

    2015-12-01

    Full Text Available The paper presents concepts for increasing the efficiency of a modern combined cycle power plant. Improvement of gas turbine performance indicators as well as recovering heat from the air cooling the gas turbine’s flow system enable reaching gross electrical efficiencies of around 65%. Analyses for a wide range of compressor pressure ratios were performed. Operating characteristics were developed for the analysed combined cycle plant, for different types of open air cooling arrangements of the gas turbine’s expander: convective, transpiration and film.

  20. Center for Hypersonic Combined Cycle Flow Physics

    Science.gov (United States)

    2015-03-24

    scales, the PaSR model may behave like a perfectly-stirred reactor (PSR) or a plug - flow reactor . In our PaSR analysis, the pair-wise mixing model...AFRL-AFOSR-VA-TR-2015-0292 CENTER FOR HYPERSONIC COMBINED CYCLE FLOW PHYSICS James Mcdaniel UNIVERSITY OF VIRGINIA Final Report 03/24/2015...HYPERSONIC COMBINED CYCLE FLOW PHYSICS 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-09-1-0611 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) McDaniel, James C

  1. Fuel cycle based safeguards

    International Nuclear Information System (INIS)

    De Montmollin, J.M.; Higinbotham, W.A.; Gupta, D.

    1985-07-01

    In NPT safeguards the same model approach and absolute-quantity inspection goals are applied at present to all similar facilities, irrespective of the State's fuel cycle. There is a continuing interest and activity on the part of the IAEA in new NPT safeguards approaches that more directly address a State's nuclear activities as a whole. This fuel cycle based safeguards system is expected to a) provide a statement of findings for the entire State rather than only for individual facilities; b) allocate inspection efforts so as to reflect more realistically the different categories of nuclear materials in the different parts of the fuel cycle and c) provide more timely and better coordinated information on the inputs, outputs and inventories of nuclear materials in a State. (orig./RF) [de

  2. Parametric Investigation and Thermoeconomic Optimization of a Combined Cycle for Recovering the Waste Heat from Nuclear Closed Brayton Cycle

    Directory of Open Access Journals (Sweden)

    Lihuang Luo

    2016-01-01

    Full Text Available A combined cycle that combines AWM cycle with a nuclear closed Brayton cycle is proposed to recover the waste heat rejected from the precooler of a nuclear closed Brayton cycle in this paper. The detailed thermodynamic and economic analyses are carried out for the combined cycle. The effects of several important parameters, such as the absorber pressure, the turbine inlet pressure, the turbine inlet temperature, the ammonia mass fraction, and the ambient temperature, are investigated. The combined cycle performance is also optimized based on a multiobjective function. Compared with the closed Brayton cycle, the optimized power output and overall efficiency of the combined cycle are higher by 2.41% and 2.43%, respectively. The optimized LEC of the combined cycle is 0.73% lower than that of the closed Brayton cycle.

  3. High performance integrated solar combined cycles with minimum modifications to the combined cycle power plant design

    International Nuclear Information System (INIS)

    Manente, Giovanni

    2016-01-01

    Highlights: • Off-design model of a 390 MW e three pressure combined cycle developed and validated. • The off-design model is used to evaluate different hybridization schemes with solar. • Power boosting and fuel saving with different design modifications are considered. • Maximum solar share of total electricity is only 1% with the existing equipment. • The maximum incremental solar radiation-to-electrical efficiency approaches 29%. - Abstract: The integration of solar energy into natural gas combined cycles has been successfully demonstrated in several integrated solar combined cycles since the beginning of this decade in many countries. There are many motivations that drive investments on integrated solar combined cycles which are primarily the repowering of existing power plants, the compliance with more severe environmental laws on emissions and the mitigation of risks associated with large solar projects. Integrated solar combined cycles are usually developed as brownfield facilities by retrofitting existing natural gas combined cycles and keeping the existing equipment to minimize costs. In this work a detailed off-design model of a 390 MW e three pressure level natural gas combined cycle is built to evaluate different integration schemes of solar energy which either keep the equipment of the combined cycle unchanged or include new equipment (steam turbine, heat recovery steam generator). Both power boosting and fuel saving operation strategies are analyzed in the search for the highest annual efficiency and solar share. Results show that the maximum incremental power output from solar at design solar irradiance is limited to 19 MW e without modifications to the existing equipment. Higher values are attainable only including a larger steam turbine. High solar radiation-to-electrical efficiencies in the range 24–29% can be achieved in the integrated solar combined cycle depending on solar share and extension of tube banks in the heat recovery

  4. Modeling of a combined cycle power plant

    International Nuclear Information System (INIS)

    Faridah Mohamad Idris

    2001-01-01

    The combined cycle power plant is a non-linear, closed loop system, which consists of high-pressure (HP) superheater, HP evaporator, HP economizer, low-pressure (LP) evaporator, HP drum, HP deaerator, condenser, HP and LP steam turbine and gas turbine. The two types of turbines in the plant for example the gas turbine and the HP and LP steam turbines operate concurrently to generate power to the plant. The exhaust gas which originate from the combustion chamber drives the gas turbine, after which it flows into the heat recovery steam generator (HRSG) to generate superheated steam to be used in driving the HP and LP steam turbines. In this thesis, the combined cycle power plant is modeled at component level using the physical method. Assuming that there is delay in transport, except for the gas turbine system, the mass and heat balances are applied on the components of the plant to derive the governing equations of the components. These time dependent equations, which are of first order differential types, are then solved for the mass and enthalpy of the components. The solutions were simulated using Matlab Simulink using measured plant data. Where necessary there is no plant data available, approximated data were used. The generalized regression neural networks are also used to generate extra sets of simulation data for the HRSG system. Comparisons of the simulation results with its corresponding plant data showed good agreements between the two and indicated that the models developed for the components could be used to represent the combined cycle power plant under study. (author)

  5. Analysis and performance assessment of a new solar-based multigeneration system integrated with ammonia fuel cell and solid oxide fuel cell-gas turbine combined cycle

    Science.gov (United States)

    Siddiqui, Osamah; Dincer, Ibrahim

    2017-12-01

    In the present study, a new solar-based multigeneration system integrated with an ammonia fuel cell and solid oxide fuel cell-gas turbine combined cycle to produce electricity, hydrogen, cooling and hot water is developed for analysis and performance assessment. In this regard, thermodynamic analyses and modeling through both energy and exergy approaches are employed to assess and evaluate the overall system performance. Various parametric studies are conducted to study the effects of varying system parameters and operating conditions on the energy and exergy efficiencies. The results of this study show that the overall multigeneration system energy efficiency is obtained as 39.1% while the overall system exergy efficiency is calculated as 38.7%, respectively. The performance of this multigeneration system results in an increase of 19.3% in energy efficiency as compared to single generation system. Furthermore, the exergy efficiency of the multigeneration system is 17.8% higher than the single generation system. Moreover, both energy and exergy efficiencies of the solid oxide fuel cell-gas turbine combined cycle are determined as 68.5% and 55.9% respectively.

  6. Analysis of an integrated solar combined cycle with steam and organic Rankine cycles as bottoming cycles

    International Nuclear Information System (INIS)

    Shaaban, S.

    2016-01-01

    Highlights: • A novel ISCC with steam and organic Rankine cycles ORC as bottoming cycles was introduced. • The operating conditions of the cycle were optimized using the genetic optimization algorithm. • R1234ze(z) was found to be the best working fluid for the bottoming ORC. • The output power was improved by 19.5% with solar contribution and 23.1% without solar contribution. • The proposed cycle is less affected by variations of the ambient temperature. - Abstract: Integrated Solar Combined Cycles (ISCC) are currently used in countries with high incident solar radiation in order to increase the net output power and decrease the specific fuel consumption. The present work introduces a modified ISCC with two bottoming cycles. The first bottoming cycle is a steam Rankine cycle while the second one is an Organic Rankine Cycle ORC. Multistage compression with intercooling was considered for the gas turbine unit. The ORC was used in order to intercool the compressed air and produce a net power from the received thermal energy. The proposed cycle performance was studied and optimized. Fifteen working fluids were investigated for use with the ORC. Results showed that R1234ze(z) introduces a good compromise between thermodynamics, economic, safety and environmental considerations. The cycle with R1234ze(z) as a working fluid showed an increase of the output power by 19.5% with solar contribution and 23.1% without solar contribution. The increase of the net output power with the application of the proposed cycle is higher than the power produced from a 50 MW solar field. Moreover, the proposed cycle is less affected by variations of the ambient temperature.

  7. Research on shock wave characteristics in the isolator of central strut rocket-based combined cycle engine under Ma5.5

    Science.gov (United States)

    Wei, Xianggeng; Xue, Rui; Qin, Fei; Hu, Chunbo; He, Guoqiang

    2017-11-01

    A numerical calculation of shock wave characteristics in the isolator of central strut rocket-based combined cycle (RBCC) engine fueled by kerosene was carried out in this paper. A 3D numerical model was established by the DES method. The kerosene chemical kinetic model used the 9-component and 12-step simplified mechanism model. Effects of fuel equivalence ratio, inflow total temperature and central strut rocket on-off on shock wave characteristics were studied under Ma5.5. Results demonstrated that with the increase of equivalence ratio, the leading shock wave moves toward upstream, accompanied with higher possibility of the inlet unstart. However, the leading shock wave moves toward downstream as the inflow total temperature rises. After the central strut rocket is closed, the leading shock wave moves toward downstream, which can reduce risks of the inlet unstart. State of the shear layer formed by the strut rocket jet flow and inflow can influence the shock train structure significantly.

  8. INTEGRATED PYROLYSIS COMBINED CYCLE BIOMASS POWER SYSTEM CONCEPT DEFINITION

    Energy Technology Data Exchange (ETDEWEB)

    Eric Sandvig; Gary Walling; Robert C. Brown; Ryan Pletka; Desmond Radlein; Warren Johnson

    2003-03-01

    Advanced power systems based on integrated gasification/combined cycles (IGCC) are often presented as a solution to the present shortcomings of biomass as fuel. Although IGCC has been technically demonstrated at full scale, it has not been adopted for commercial power generation. Part of the reason for this situation is the continuing low price for coal. However, another significant barrier to IGCC is the high level of integration of this technology: the gas output from the gasifier must be perfectly matched to the energy demand of the gas turbine cycle. We are developing an alternative to IGCC for biomass power: the integrated (fast) pyrolysis/ combined cycle (IPCC). In this system solid biomass is converted into liquid rather than gaseous fuel. This liquid fuel, called bio-oil, is a mixture of oxygenated organic compounds and water that serves as fuel for a gas turbine topping cycle. Waste heat from the gas turbine provides thermal energy to the steam turbine bottoming cycle. Advantages of the biomass-fueled IPCC system include: combined cycle efficiency exceeding 37 percent efficiency for a system as small as 7.6 MW{sub e}; absence of high pressure thermal reactors; decoupling of fuel processing and power generation; and opportunities for recovering value-added products from the bio-oil. This report provides a technical overview of the system including pyrolyzer design, fuel clean-up strategies, pyrolysate condenser design, opportunities for recovering pyrolysis byproducts, gas turbine cycle design, and Rankine steam cycle. The report also reviews the potential biomass fuel supply in Iowa, provide and economic analysis, and present a summery of benefits from the proposed system.

  9. INTEGRATED PYROLYSIS COMBINED CYCLE BIOMASS POWER SYSTEM CONCEPT DEFINITION

    International Nuclear Information System (INIS)

    Sandvig, Eric; Walling, Gary; Brown, Robert C.; Pletka, Ryan; Radlein, Desmond; Johnson, Warren

    2003-01-01

    Advanced power systems based on integrated gasification/combined cycles (IGCC) are often presented as a solution to the present shortcomings of biomass as fuel. Although IGCC has been technically demonstrated at full scale, it has not been adopted for commercial power generation. Part of the reason for this situation is the continuing low price for coal. However, another significant barrier to IGCC is the high level of integration of this technology: the gas output from the gasifier must be perfectly matched to the energy demand of the gas turbine cycle. We are developing an alternative to IGCC for biomass power: the integrated (fast) pyrolysis/ combined cycle (IPCC). In this system solid biomass is converted into liquid rather than gaseous fuel. This liquid fuel, called bio-oil, is a mixture of oxygenated organic compounds and water that serves as fuel for a gas turbine topping cycle. Waste heat from the gas turbine provides thermal energy to the steam turbine bottoming cycle. Advantages of the biomass-fueled IPCC system include: combined cycle efficiency exceeding 37 percent efficiency for a system as small as 7.6 MW e ; absence of high pressure thermal reactors; decoupling of fuel processing and power generation; and opportunities for recovering value-added products from the bio-oil. This report provides a technical overview of the system including pyrolyzer design, fuel clean-up strategies, pyrolysate condenser design, opportunities for recovering pyrolysis byproducts, gas turbine cycle design, and Rankine steam cycle. The report also reviews the potential biomass fuel supply in Iowa, provide and economic analysis, and present a summery of benefits from the proposed system

  10. A Humid Air Turbine–Organic Rankine Cycle combined cycle for distributed microgeneration

    International Nuclear Information System (INIS)

    Chacartegui, Ricardo; Becerra, José A.; Blanco, Maria J.; Muñoz-Escalona, José M.

    2015-01-01

    Highlights: • Humid Air microTurbine and Organic Rankine Cycle models. • Micro combined cycle with optimized medium/low temperature heat recovery. • Thermodynamic analyses of different integrations, fluids and parameters. • Outstanding performance parameters in the distributed generation power range. • Economic analyses show the high viability of the proposed concept. - Abstract: This paper analyses the integration of Humid Air microturbine and an Organic Rankine Cycle in a combined cycle for distributed generation. This integration concept maximizes heat recovery at the exhaust of the micro gas turbine combining the capacities for medium temperature heat recovery of the Organic Rankine Cycle and low temperature heat recovery of the Humid Air Turbine. The integration analysis based on different sets of organic fluids and different recovery temperatures showed that the optimal combination was achieved using toluene and R245fa for medium and low temperature Organic Rankine Cycles respectively. Their combination with the low temperature heat recovery at the Humid Air Turbine saturator maximizes the heat recovery profile from the exhaust gases. The calculations carried out reveal a 25% improvement in net power output of the dual cycle compared to the standalone Humid Air microturbine. Such improvement also affects to global efficiency, increasing it up to 52% in the optimal configuration, above the 41% estimated for the standalone Humid Air Turbine and the 33% rated efficiency of the state of art microturbine Capstone C200. The economic analysis shows that these increases in efficiency and power values make the proposed concept highly competitive, with a 15% reduction in the Levelized Cost of Electricity compared with the standalone Humid Air Turbine and a reduction of 30% compared with the micro gas turbine base case. The presented results show this novel integration as a very promising solution for distributed generation applications at power range under

  11. Open-Cycle Gas Turbine/Steam Turbine Combined Cycles with synthetic fuels from coal

    Science.gov (United States)

    Shah, R. P.; Corman, J. C.

    1977-01-01

    The Open-Cycle Gas Turbine/Steam Turbine Combined Cycle can be an effective energy conversion system for converting coal to electricity. The intermediate step in this energy conversion process is to convert the coal into a fuel acceptable to a gas turbine. This can be accomplished by producing a synthetic gas or liquid, and by removing, in the fuel conversion step, the elements in the fuel that would be harmful to the environment if combusted. In this paper, two open-cycle gas turbine combined systems are evaluated: one employing an integrated low-Btu gasifier, and one utilizing a semi-clean liquid fuel. A consistent technical/economic information base is developed for these two systems, and is compared with a reference steam plant burning coal directly in a conventional furnace.

  12. Characterization and functional analysis of a slow-cycling subpopulation in colorectal cancer enriched by cell cycle inducer combined chemotherapy.

    Science.gov (United States)

    Wu, Feng-Hua; Mu, Lei; Li, Xiao-Lan; Hu, Yi-Bing; Liu, Hui; Han, Lin-Tao; Gong, Jian-Ping

    2017-10-03

    The concept of cancer stem cells has been proposed in various malignancies including colorectal cancer. Recent studies show direct evidence for quiescence slow-cycling cells playing a role in cancer stem cells. There exists an urgent need to isolate and better characterize these slow-cycling cells. In this study, we developed a new model to enrich slow-cycling tumor cells using cell-cycle inducer combined with cell cycle-dependent chemotherapy in vitro and in vivo . Our results show that Short-term exposure of colorectal cancer cells to chemotherapy combined with cell-cycle inducer enriches for a cell-cycle quiescent tumor cell population. Specifically, these slow-cycling tumor cells exhibit increased chemotherapy resistance in vitro and tumorigenicity in vivo . Notably, these cells are stem-cell like and participate in metastatic dormancy. Further exploration indicates that slow-cycling colorectal cancer cells in our model are less sensitive to cytokine-induced-killer cell mediated cytotoxic killing in vivo and in vitro . Collectively, our cell cycle inducer combined chemotherapy exposure model enriches for a slow-cycling, dormant, chemo-resistant tumor cell sub-population that are resistant to cytokine induced killer cell based immunotherapy. Studying unique signaling pathways in dormant tumor cells enriched by cell cycle inducer combined chemotherapy treatment is expected to identify novel therapeutic targets for preventing tumor recurrence.

  13. Cycle bases to the rescue

    Science.gov (United States)

    Tóbiás, Roland; Furtenbacher, Tibor; Császár, Attila G.

    2017-12-01

    Cycle bases of graph theory are introduced for the analysis of transition data deposited in line-by-line rovibronic spectroscopic databases. The principal advantage of using cycle bases is that outlier transitions -almost always present in spectroscopic databases built from experimental data originating from many different sources- can be detected and identified straightforwardly and automatically. The data available for six water isotopologues, H216O, H217O, H218O, HD16O, HD17O, and HD18O, in the HITRAN2012 and GEISA2015 databases are used to demonstrate the utility of cycle-basis-based outlier-detection approaches. The spectroscopic databases appear to be sufficiently complete so that the great majority of the entries of the minimum cycle basis have the minimum possible length of four. More than 2000 transition conflicts have been identified for the isotopologue H216O in the HITRAN2012 database, the seven common conflict types are discussed. It is recommended to employ cycle bases, and especially a minimum cycle basis, for the analysis of transitions deposited in high-resolution spectroscopic databases.

  14. Thermodynamic Modeling for Open Combined Regenerative Brayton and Inverse Brayton Cycles with Regeneration before the Inverse Cycle

    Directory of Open Access Journals (Sweden)

    Lingen Chen

    2012-01-01

    Full Text Available A thermodynamic model of an open combined regenerative Brayton and inverse Brayton cycles with regeneration before the inverse cycle is established in this paper by using thermodynamic optimization theory. The flow processes of the working fluid with the pressure drops and the size constraint of the real power plant are modeled. There are 13 flow resistances encountered by the working fluid stream for the cycle model. Four of these, the friction through the blades and vanes of the compressors and the turbines, are related to the isentropic efficiencies. The remaining nine flow resistances are always present because of the changes in flow cross-section at the compressor inlet of the top cycle, regenerator inlet and outlet, combustion chamber inlet and outlet, turbine outlet of the top cycle, turbine outlet of the bottom cycle, heat exchanger inlet, and compressor inlet of the bottom cycle. These resistances associated with the flow through various cross-sectional areas are derived as functions of the compressor inlet relative pressure drop of the top cycle, and control the air flow rate, the net power output and the thermal efficiency. The analytical formulae about the power output, efficiency and other coefficients are derived with 13 pressure drop losses. It is found that the combined cycle with regenerator can reach higher thermal efficiency but smaller power output than those of the base combined cycle at small compressor inlet relative pressure drop of the top cycle.

  15. A comparison of advanced heat recovery power cycles in a combined cycle for large ships

    DEFF Research Database (Denmark)

    Larsen, Ulrik; Sigthorsson, Oskar; Haglind, Fredrik

    2014-01-01

    Strong motivation exists within the marine sector to reduce fuel expenses and to comply with ever stricter emission regulations. Heat recovery can address both of these issues. The ORC (organic Rankine cycle), the Kalina cycle and the steam Rankine cycle have received the majority of the focus...... model is combined with a turbocharger model and bottoming cycle models written in Matlab. Genetic algorithm optimisation results suggest that the Kalina cycle possess no significant advantages compared to the ORC or the steam cycle. While contributing to very high efficiencies, the organic working...... in the literature. In the present work we compare these cycles in a combined cycle application with a large marine two-stroke diesel engine. We present an evaluation of the efficiency and the environmental impact, safety concerns and practical aspects of each of the cycles. A previously validated numerical engine...

  16. Combination of IVF and IVM in naturally cycling women

    DEFF Research Database (Denmark)

    Tang-Pedersen, Mikael; Westergaard, Lars Grabow; Erb, Karin

    2012-01-01

    seems less than reported in other IVM protocols. Though the combined concept of IVM and natural-cycle IVF is possible and there are ongoing pregnancies from both IVM and in-vivo matured eggs, we recommend either optimizing an IVM programme or using natural-cycle IVF rather than our original approach.......This study investigated the combination of an unstimulated IVF cycle with in-vitro maturation (IVM) of additional immature cumulus-oocyte-complexes (COC) from the same cycle collected at the same time as the spontaneous preovulatory follicle. This could potentially improve rates of embryo transfer...... is one of the potential treatments which eliminates the risk of ovarian hyperstimulation syndrome and minimizes the side-effects of medication. At the same time, natural-cycle IVF without hormonal stimulation is also experiencing a revival. By combining IVM and natural-cycle IVF, we aimed for to improve...

  17. CANDU combined cycles featuring gas-turbine engines

    International Nuclear Information System (INIS)

    Vecchiarelli, J.; Choy, E.; Peryoga, Y.; Aryono, N.A.

    1998-01-01

    thermodynamic evaluation of various CANDU gas-turbine combined cycles. For the evaluation, a minimal number and size of gas-turbine engines were considered, specifically, 4x50 MWe (based on CANDU 6). With this set of gas turbines, it is calculated that a relatively high level of reliability of class IV power restoration can be attained. The results from the GateCycle analysis indicate that certain CANDU combined cycles can generate over 940 MWe (net) with an overall thermal efficiency of up to 37% (which is about 4 percentage points higher than that of the current CANDU 6). Hence, the proposed concept may significantly enhance the competitiveness of future CANDU plants. This is especially important in light of: (a) advancements in combined-cycle technology and (b) recent studies on the thermal coupling of gas turbines with future light water reactors. (author)

  18. Performance analysis and modeling of energy from waste combined cycles

    International Nuclear Information System (INIS)

    Qiu, K.; Hayden, A.C.S.

    2009-01-01

    Municipal solid waste (MSW) is produced in a substantial amount with minimal fluctuations throughout the year. The analysis of carbon neutrality of MSW on a life cycle basis shows that MSW is about 67% carbon-neutral, suggesting that only 33% of the CO 2 emissions from incinerating MSW are of fossil origin. The waste constitutes a 'renewable biofuel' energy resource and energy from waste (EfW) can result in a net reduction in CO 2 emissions. In this paper, we explore an approach to extracting energy from MSW efficiently - EfW/gas turbine hybrid combined cycles. This approach innovates by delivering better performance with respect to energy efficiency and CO 2 mitigation. In the combined cycles, the topping cycle consists of a gas turbine, while the bottoming cycle is a steam cycle where the low quality fuel - waste is utilized. This paper assesses the viability of the hybrid combined cycles and analyses their thermodynamic advantages with the help of computer simulations. It was shown that the combined cycles could offer significantly higher energy conversion efficiency and a practical solution to handling MSW. Also, the potential for a net reduction in CO 2 emissions resulting from the hybrid combined cycles was evaluated.

  19. [Combined hormonal contraception in cycles artificially extended].

    Science.gov (United States)

    Bustillos-Alamilla, Edgardo; Zepeda-Zaragoza, J; Hernández-Ruiz, M A; Briones-Landa, Carlos Humberto

    2010-01-01

    To compare the bleeding patterns, satisfaction and tolerability of 3 different contraceptive in an extended regimens in the service of Family Planning of the North Central Hospital of PEMEX. Healthy, adult women with desire of contraception for one year (N 120) were randomly assigned to receive oral contraceptive drospirenone/ethinyl E2 (group1), the norelgestromin/ethinyl E2 transdermal patch (group 2) and vaginal ring etonogestrel/ ethinyl E2 (group 3) in an extended regimen (42 consecutive days, 1 hormone-free week). Study assessments were conducted at scheduled visits at the time of initial screening, at baseline after 1, 3, 6, and 12 months. Subjects recorded menstrual associated symptoms bleeding data and completed satisfaction questionnaires. Subjects and investigators provided overall assessments of the regimens. Extended use of 3 different contraceptive resulted in fewer bleeding days in every group (66.6%, 55% and 58.3% P 0.0024), and less mastalgia and menstrual pain. Subjects were highly satisfied with three regimens (93.3%, 96.6% and 91.6% P 0.00421). Although not mayor adverse events were reported with this regimen, there was an increase in spotting days; it decreased with each successive cycle of therapy. Efficacy and safety were similar to those reported for traditional cycle. Extended-contraceptive regimen delays menses and reduces bleeding, a profile that may be preferred by women who seek flexibility with their contraceptive method.

  20. Preliminary Modelling Results for an Otto Cycle/Stirling Cycle Hybrid-engine-based Power Generation System

    OpenAIRE

    Cullen, Barry; McGovern, Jim; Feidt, Michel; Petrescu, Stoian

    2009-01-01

    This paper presents preliminary data and results for a system mathematical model for a proposed Otto Cycle / Stirling Cycle hybrid-engine-based power generation system. The system is a combined cycle system with the Stirling cycle machine operating as a bottoming cycle on the Otto cycle exhaust. The application considered is that of a stationary power generation scenario wherein the Stirling cycle engine operates as a waste heat recovery device on the exhaust stream of the Otto cycle engine. ...

  1. Gasification and combined cycles: Present situation and future prospects

    International Nuclear Information System (INIS)

    Brustia, G.F.; Bressan, L.; Domenichini, R.

    1992-01-01

    The gasification of coal and/or residual fuels from refineries together with the use of combined cycle power generation systems represents a technically and economically feasible method for the conversion of poor quality fossil fuels into electric power. The conversion is accomplished with maximum respect for the severest environmental normatives. In addition, foreseen technical improvements for components and plant systems are expected to heighten the marketing potential of gasification/combined cycle power plants. After Italy's moratorium on nuclear energy, the passing eras of conventional fossil fuel and then combined cycle power plants, the need for highly competitive industrial production technologies and the urgency of nation-wide energy conservation appear to be ushering in the new era of gasification with combined cycles

  2. Start-up Optimization of a Combined Cycle Power Plant

    OpenAIRE

    Sällberg, Elin; Lind, Alexandra; Velut, Stéphane; Åkesson, Johan; Gallardo Yances, Stephanie; Link, Kilian

    2012-01-01

    In the electricity market of today, with increasing demand for electricity production on short notice, the combined cycle power plant stands high regarding fast start-ups and efficiency. In this paper it has been shown how the dynamic start-up procedure of a combined cycle power plant can be optimized using JModelica. org, proposing a way to minimize the start-up time while maximizing the power production during start-up. The physical models have been developed in M...

  3. Exergy Analysis of Combined Cycle Power Plant: NTPC Dadri, India

    OpenAIRE

    Tiwari, Arvind; Hasan, M; Islam, Mohd.

    2012-01-01

    The aim of the present paper is to exergy analysis of combined Brayton/Rankine power cycle of NTPC Dadri India. Theoretical exergy analysis is carried out for different components of dadri combined cycle power plant which consists of a gas turbine unit, heat recovery steam generator without extra fuel consumption and steam turbine unit. The results pinpoint that more exergy losses occurred in the gas turbine combustion chamber. Its reached 35% of the total exergy losses while the exergy losse...

  4. A comparison of advanced heat recovery power cycles in a combined cycle for large ships

    International Nuclear Information System (INIS)

    Larsen, Ulrik; Sigthorsson, Oskar; Haglind, Fredrik

    2014-01-01

    Strong motivation exists within the marine sector to reduce fuel expenses and to comply with ever stricter emission regulations. Heat recovery can address both of these issues. The ORC (organic Rankine cycle), the Kalina cycle and the steam Rankine cycle have received the majority of the focus in the literature. In the present work we compare these cycles in a combined cycle application with a large marine two-stroke diesel engine. We present an evaluation of the efficiency and the environmental impact, safety concerns and practical aspects of each of the cycles. A previously validated numerical engine model is combined with a turbocharger model and bottoming cycle models written in Matlab. Genetic algorithm optimisation results suggest that the Kalina cycle possess no significant advantages compared to the ORC or the steam cycle. While contributing to very high efficiencies, the organic working fluids possess high global warming potentials and hazard levels. It is concluded that the ORC has the greatest potential for increasing the fuel efficiency, and the combined cycle offers very high thermal efficiency. While being less efficient, the steam cycle has the advantages of being well proven, harmless to the environment as well as being less hazardous in comparison. - Highlights: • We compare steam, ORC (organic Rankine cycle) and Kalina cycles for waste heat recovery in marine engines. • We evaluate the efficiency and important qualitative differences. • The Kalina cycle presents no apparent advantages. • The steam cycle is well known, harmless and has a high efficiency. • The ORC has the highest efficiency but also important drawbacks

  5. Variable geometry gas turbines for improving the part-load performance of marine combined cycles - Combined cycle performance

    DEFF Research Database (Denmark)

    Haglind, Fredrik

    2011-01-01

    cycles used for ship propulsion. Moreover, the paper is aimed at developing methodologies and deriving models for part-load simulations suitable for energy system analysis of various components within combined cycle power plants. Two different gas turbine configurations are studied, a two-shaft aero...

  6. Hybrid Combined Cycles with Biomass and Waste Fired Bottoming Cycle - a Literature Study

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Miroslav P.

    2002-02-01

    Biomass is one of the main natural resources in Sweden. The present low-CO{sub 2} emission characteristics of the Swedish electricity production system (hydro and nuclear) can be retained only by expansion of biofuel applications for energy purposes. Domestic Swedish biomass resources are vast and renewable, but not infinite. They must be utilized as efficiently as possible, in order to make sure that they meet the conditions for sustainability in the future. Application of efficient power generation cycles at low costs is essential for meeting this challenge. This applies also to municipal solid waste incineration with energy extraction, which should be preferred to its dumping in landfills. Hybrid dual-fuel combined cycle units are a simple and affordable way to increase the electric efficiency of biofuel energy utilization, without big investments, uncertainties or loss of reliability arising from complicated technologies. Configurations of such power cycles are very flexible and reliable. Their potential for high electric efficiency in condensing mode, high total efficiency in combined heat and power mode and unrivalled load flexibility is explored in this project. The present report is a literature study that concentrates on certain biomass utilization technologies, in particular the design and performance of hybrid combined cycle power units of various configurations, with gas turbines and internal combustion engines as topping cycles. An overview of published literature and general development trends on the relevant topic is presented. The study is extended to encompass a short overview of biomass utilization as an energy source (focusing on Sweden), history of combined cycles development with reference especially to combined cycles with supplementary firing and coal-fired hybrid combined cycles, repowering of old steam units into hybrid ones and combined cycles for internal combustion engines. The hybrid combined cycle concept for municipal solid waste

  7. Modeling and optimization of a hybrid solar combined cycle (HYCS)

    Science.gov (United States)

    Eter, Ahmad Adel

    2011-12-01

    The main objective of this thesis is to investigate the feasibility of integrating concentrated solar power (CSP) technology with the conventional combined cycle technology for electric generation in Saudi Arabia. The generated electricity can be used locally to meet the annual increasing demand. Specifically, it can be utilized to meet the demand during the hours 10 am-3 pm and prevent blackout hours, of some industrial sectors. The proposed CSP design gives flexibility in the operation system. Since, it works as a conventional combined cycle during night time and it switches to work as a hybrid solar combined cycle during day time. The first objective of the thesis is to develop a thermo-economical mathematical model that can simulate the performance of a hybrid solar-fossil fuel combined cycle. The second objective is to develop a computer simulation code that can solve the thermo-economical mathematical model using available software such as E.E.S. The developed simulation code is used to analyze the thermo-economic performance of different configurations of integrating the CSP with the conventional fossil fuel combined cycle to achieve the optimal integration configuration. This optimal integration configuration has been investigated further to achieve the optimal design of the solar field that gives the optimal solar share. Thermo-economical performance metrics which are available in the literature have been used in the present work to assess the thermo-economic performance of the investigated configurations. The economical and environmental impact of integration CSP with the conventional fossil fuel combined cycle are estimated and discussed. Finally, the optimal integration configuration is found to be solarization steam side in conventional combined cycle with solar multiple 0.38 which needs 29 hectare and LEC of HYCS is 63.17 $/MWh under Dhahran weather conditions.

  8. Thermodynamic Study of Multi Pressure HRSG in Gas/Steam Combined Cycle Power Plant

    Science.gov (United States)

    Sharma, Meeta; Singh, Onkar

    2018-01-01

    Combined cycle power plants have a combination of gas based topping cycle and steam based bottoming cycle through the use of Heat Recovery Steam Generator (HRSG). These HRSG may be either of single pressure (SP) or dual pressure (DP) or multiple pressure type. Here in this study thermodynamic analysis is carried out for optimal performance of HRSG using different types of HRSG layout for combined cycle efficiency improvement. Performance of single pressure HRSG and dual pressure HRSG, utilized in gas/steam combined cycle is analyzed and presented here. In comparison to single pressure, dual pressure HRSG offers 10 to 15% higher reduction in stack temperature due to greater heat recovery and thus improved plant efficiency.

  9. Thermodynamic performance optimization of a combined power/cooling cycle

    International Nuclear Information System (INIS)

    Pouraghaie, M.; Atashkari, K.; Besarati, S.M.; Nariman-zadeh, N.

    2010-01-01

    A combined thermal power and cooling cycle has already been proposed in which thermal energy is used to produce work and to generate a sub-ambient temperature stream that is suitable for cooling applications. The cycle uses ammonia-water mixture as working fluid and is a combination of a Rankine cycle and absorption cycle. The very high ammonia vapor concentration, exiting turbine under certain operating conditions, can provide power output as well as refrigeration. In this paper, the goal is to employ multi-objective algorithms for Pareto approach optimization of thermodynamic performance of the cycle. It has been carried out by varying the selected design variables, namely, turbine inlet pressure (P h ), superheater temperature (T superheat ) and condenser temperature (T condensor ). The important conflicting thermodynamic objective functions that have been considered in this study are turbine work (w T ), cooling capacity (q cool ) and thermal efficiency (η th ) of the cycle. It is shown that some interesting and important relationships among optimal objective functions and decision variables involved in the combined cycle can be discovered consequently. Such important relationships as useful optimal design principles would have not been obtained without the use of a multi-objective optimization approach.

  10. Exergy analysis for combined regenerative Brayton and inverse Brayton cycles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zelong; Chen, Lingen; Sun, Fengrui [College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033 (China)

    2012-07-01

    This paper presents the study of exergy analysis of combined regenerative Brayton and inverse Brayton cycles. The analytical formulae of exergy loss and exergy efficiency are derived. The largest exergy loss location is determined. By taking the maximum exergy efficiency as the objective, the choice of bottom cycle pressure ratio is optimized by detailed numerical examples, and the corresponding optimal exergy efficiency is obtained. The influences of various parameters on the exergy efficiency and other performances are analyzed by numerical calculations.

  11. Optimization of the triple-pressure combined cycle power plant

    OpenAIRE

    Alus Muammer; Petrović Milan V.

    2012-01-01

    The aim of this work was to develop a new system for optimization of parameters for combined cycle power plants (CCGTs) with triple-pressure heat recovery steam generator (HRSG). Thermodynamic and thermoeconomic optimizations were carried out. The objective of the thermodynamic optimization is to enhance the efficiency of the CCGTs and to maximize the power production in the steam cycle (steam turbine gross power). Improvement of the efficiency of the CCGT plants is achieved through opt...

  12. The development of Coke Carried-Heat Gasification Coal-Fired Combined Cycle

    Science.gov (United States)

    Zhao, Li; Xu, Xiangdong

    1999-12-01

    Carried-Heat Partial Gasification Combined cycle is a novel combined cycle which was proposed by Thermal Engineering Department of Tsinghua University in 1992. The idea of the system comes from the situation that the efficiency of the power plants in China is much lower than that of the advanced countries, but the coal consumption is much higher, which brings about the waste of primary energy resources and the pollution of the environment. With the deep study of the gasification technology, Coke Carried-Heat Gasification Coal-Fired Combined Cycle, as the improved system, came into birth in 1996 based on the partial gasification one. At the end of 1997, a new cycle scheme similar to IGCC was created. This paper focuses on several classes combined cycle put forward by Tsinghua University, depending on the plant configuration and carbon conversion, making the solution a viable and attractive option for efficient coal utilization.

  13. Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part A

    DEFF Research Database (Denmark)

    Meroni, Andrea; La Seta, Angelo; Andreasen, Jesper Graa

    2016-01-01

    Rankine cycle power systems. In this two-part paper, an overall cycle model and a model of an axial turbine were combined in order to provide a comprehensive preliminary design of the organic Rankine cycle unit, taking into account both cycle and turbine optimal designs. Part A presents the preliminary...... turbine design model, the details of the validation and a sensitivity analysis on the main parameters, in order to minimize the number of decision variables in the subsequent turbine design optimization. Part B analyzes the application of the combined turbine and cycle designs on a selected case study...... of validation. Discrepancy below 12% was obtained in the estimation of the flow velocities and turbine geometry. The values are considered to be within a reasonable range for a preliminary design tool. The sensitivity analysis on the turbine model suggests that two of twelve decision variables of the model can...

  14. A combined gas cooled nuclear reactor and fuel cell cycle

    Science.gov (United States)

    Palmer, David J.

    Rising oil costs, global warming, national security concerns, economic concerns and escalating energy demands are forcing the engineering communities to explore methods to address these concerns. It is the intention of this thesis to offer a proposal for a novel design of a combined cycle, an advanced nuclear helium reactor/solid oxide fuel cell (SOFC) plant that will help to mitigate some of the above concerns. Moreover, the adoption of this proposal may help to reinvigorate the Nuclear Power industry while providing a practical method to foster the development of a hydrogen economy. Specifically, this thesis concentrates on the importance of the U.S. Nuclear Navy adopting this novel design for its nuclear electric vessels of the future with discussion on efficiency and thermodynamic performance characteristics related to the combined cycle. Thus, the goals and objectives are to develop an innovative combined cycle that provides a solution to the stated concerns and show that it provides superior performance. In order to show performance, it is necessary to develop a rigorous thermodynamic model and computer program to analyze the SOFC in relation with the overall cycle. A large increase in efficiency over the conventional pressurized water reactor cycle is realized. Both sides of the cycle achieve higher efficiencies at partial loads which is extremely important as most naval vessels operate at partial loads as well as the fact that traditional gas turbines operating alone have poor performance at reduced speeds. Furthermore, each side of the cycle provides important benefits to the other side. The high temperature exhaust from the overall exothermic reaction of the fuel cell provides heat for the reheater allowing for an overall increase in power on the nuclear side of the cycle. Likewise, the high temperature helium exiting the nuclear reactor provides a controllable method to stabilize the fuel cell at an optimal temperature band even during transients helping

  15. Integrated system approach for increase of engine combined cycle efficiency

    International Nuclear Information System (INIS)

    Gewald, D.; Karellas, S.; Schuster, A.; Spliethoff, H.

    2012-01-01

    Highlights: ► A new approach for the optimization of engine combined cycle systems is presented. ► The efficiency can be increased by integrating all available waste heat sources. ► The optimization of the ICE cooling system towards higher temperatures is examined. ► Higher engine cooling water temperatures increase the combined cycle efficiency. ► The costs of electricity generation can be decreased by five integrated system. - Abstract: Internal combustion engines (ICEs) are widely used as independent power producers due to their high electrical efficiency (up to 47%), which can be further enhanced by operating them in combined cycle mode with a water/steam cycle as bottoming cycle. This study presents an integrated approach to optimize the combined cycle overall system efficiency. Therefore, not only the most favorable design of the waste heat recovery (WHR) cycle, but also the optimal configuration of the ICE cooling system have to be investigated, in order to integrate both available engine waste heat sources (exhaust gas, 300–400 °C, engine cooling water, 90 °C) into the waste heat recovery cycle. For the definition of the most favourable temperature level of the engine cooling water three variants of engine cooling systems are examined, with respect to technical limitations given by the ICE. In order to determine the types of engines for which this optimization approach is suitable, three types of engines with different characteristics (fuel, exhaust gas parameters) combined with a water/steam cycle are simulated, by using the calculation tools Excel and Ebsilon Professional. An energetic, exergetic and economic analysis is conducted. These reveal the impacts of the temperature level to the WHR system and to the design of the engine cooling system. The calculations performed, showed that up to 19% of the engine cooling water heat can be efficiently recovered compared to a portion of 6% in the standard system. The better recovery leads to a 5

  16. Technical and financial analysis of combined cycle gas turbine

    Directory of Open Access Journals (Sweden)

    Khan Arshad Muhammad

    2013-01-01

    Full Text Available This paper presents technical and financial models which were developed in this study to predict the overall performance of combined cycle gas turbine plant in line with the needs of independent power producers in the liberalized market of power sector. Three similar sizes of combined cycle gas turbine power projects up to 200 Megawatt of independent power producers in Pakistan were selected in-order to develop and drive the basic assumptions for the inputs of the models in view of prevailing Government of Pakistan’s two components of electricity purchasing tariff that is energy purchase price and capacity purchase price at higher voltage grid station terminal from independent power producers. The levelized electricity purchasing tariff over life of plant on gaseous fuel at 60 percent plant load factor was 6.47 cent per kilowatt hour with energy purchase price and capacity purchase prices of 3.54 and 2.93 cents per kilowatt hour respectively. The outcome of technical models of gas turbine, steam turbine and combined cycle gas turbine power were found in close agreement with the projects under consideration and provides opportunity of evaluation of technical and financial aspects of combined cycle power plant in a more simplified manner with relatively accurate results. At 105 Celsius exit temperature of heat recovery steam generator flue gases the net efficiency of combined cycle gas turbine was 48.8 percent whereas at 125 Celsius exit temperature of heat recovery steam generator flue gases it was 48.0 percent. Sensitivity analysis of selected influential components of electricity tariff was also carried out.

  17. Parametric Investigation and Thermoeconomic Optimization of a Combined Cycle for Recovering the Waste Heat from Nuclear Closed Brayton Cycle

    OpenAIRE

    Lihuang Luo; Hong Gao; Chao Liu; Xiaoxiao Xu

    2016-01-01

    A combined cycle that combines AWM cycle with a nuclear closed Brayton cycle is proposed to recover the waste heat rejected from the precooler of a nuclear closed Brayton cycle in this paper. The detailed thermodynamic and economic analyses are carried out for the combined cycle. The effects of several important parameters, such as the absorber pressure, the turbine inlet pressure, the turbine inlet temperature, the ammonia mass fraction, and the ambient temperature, are investigated. The com...

  18. Life cycle assessment of a biomass gasification combined-cycle power system

    Energy Technology Data Exchange (ETDEWEB)

    Mann, M.K.; Spath, P.L.

    1997-12-01

    The potential environmental benefits from biomass power are numerous. However, biomass power may also have some negative effects on the environment. Although the environmental benefits and drawbacks of biomass power have been debated for some time, the total significance has not been assessed. This study serves to answer some of the questions most often raised in regard to biomass power: What are the net CO{sub 2} emissions? What is the energy balance of the integrated system? Which substances are emitted at the highest rates? What parts of the system are responsible for these emissions? To provide answers to these questions, a life cycle assessment (LCA) of a hypothetical biomass power plant located in the Midwest United States was performed. LCA is an analytical tool for quantifying the emissions, resource consumption, and energy use, collectively known as environmental stressors, that are associated with converting a raw material to a final product. Performed in conjunction with a technoeconomic feasibility study, the total economic and environmental benefits and drawbacks of a process can be quantified. This study complements a technoeconomic analysis of the same process, reported in Craig and Mann (1996) and updated here. The process studied is based on the concept of power Generation in a biomass integrated gasification combined cycle (BIGCC) plant. Broadly speaking, the overall system consists of biomass production, its transportation to the power plant, electricity generation, and any upstream processes required for system operation. The biomass is assumed to be supplied to the plant as wood chips from a biomass plantation, which would produce energy crops in a manner similar to the way food and fiber crops are produced today. Transportation of the biomass and other materials is by both rail and truck. The IGCC plant is sized at 113 MW, and integrates an indirectly-heated gasifier with an industrial gas turbine and steam cycle. 63 refs., 34 figs., 32 tabs.

  19. Life cycle assessment of a biomass gasification combined-cycle power system

    Energy Technology Data Exchange (ETDEWEB)

    Mann, M.K.; Spath, P.L.

    1997-12-01

    The potential environmental benefits from biomass power are numerous. However, biomass power may also have some negative effects on the environment. Although the environmental benefits and drawbacks of biomass power have been debated for some time, the total significance has not been assessed. This study serves to answer some of the questions most often raised in regard to biomass power: What are the net CO{sub 2} emissions? What is the energy balance of the integrated system? Which substances are emitted at the highest rates? What parts of the system are responsible for these emissions? To provide answers to these questions, a life cycle assessment (LCA) of a hypothetical biomass power plant located in the Midwest United States was performed. LCA is an analytical tool for quantifying the emissions, resource consumption, and energy use, collectively known as environmental stressors, that are associated with converting a raw material to a final product. Performed in conjunction with a t echnoeconomic feasibility study, the total economic and environmental benefits and drawbacks of a process can be quantified. This study complements a technoeconomic analysis of the same process, reported in Craig and Mann (1996) and updated here. The process studied is based on the concept of power Generation in a biomass integrated gasification combined cycle (BIGCC) plant. Broadly speaking, the overall system consists of biomass production, its transportation to the power plant, electricity generation, and any upstream processes required for system operation. The biomass is assumed to be supplied to the plant as wood chips from a biomass plantation, which would produce energy crops in a manner similar to the way food and fiber crops are produced today. Transportation of the biomass and other materials is by both rail and truck. The IGCC plant is sized at 113 MW, and integrates an indirectly-heated gasifier with an industrial gas turbine and steam cycle. 63 refs., 34 figs., 32 tabs.

  20. Optimization of the triple-pressure combined cycle power plant

    Directory of Open Access Journals (Sweden)

    Alus Muammer

    2012-01-01

    Full Text Available The aim of this work was to develop a new system for optimization of parameters for combined cycle power plants (CCGTs with triple-pressure heat recovery steam generator (HRSG. Thermodynamic and thermoeconomic optimizations were carried out. The objective of the thermodynamic optimization is to enhance the efficiency of the CCGTs and to maximize the power production in the steam cycle (steam turbine gross power. Improvement of the efficiency of the CCGT plants is achieved through optimization of the operating parameters: temperature difference between the gas and steam (pinch point P.P. and the steam pressure in the HRSG. The objective of the thermoeconomic optimization is to minimize the production costs per unit of the generated electricity. Defining the optimal P.P. was the first step in the optimization procedure. Then, through the developed optimization process, other optimal operating parameters (steam pressure and condenser pressure were identified. The developed system was demonstrated for the case of a 282 MW CCGT power plant with a typical design for commercial combined cycle power plants. The optimized combined cycle was compared with the regular CCGT plant.

  1. The market outlook for integrated gasification combined cycle technology

    International Nuclear Information System (INIS)

    MacGregor, P.R.; Maslak, C.E.; Stoll, H.G.

    1991-01-01

    Integrated gasification combined cycle (IGCC) technology was developed in the 1970s and is now competitive with other coal fired technologies. Because it is a new technology, IGCC technology developments are continuing at a rapid pace and the trend in decreasing capital costs is similar to the same trend seen during the early decades of simple cycle gas turbines. Consequently, IGCC technology is expected to be even more economical during the mid and late 1990s than it is today. The objective of this paper is to provide an examination of the basic economic principles of IGCC technology and to illustrate the extent to which this technology is a viable least-cost generation addition technology. Moreover, key reliability and emissions issues are addressed in relation to the technology alternatives. This paper is organized to first review the IGCC technology and to contrast its reliability, emission, performance and cost data with the three key commercially proven technologies: simple cycle combustion turbines, combined cycle plants, and coal-fired steam plants. Economic screening curves are used to illustrate the need for a balanced generation expansion mix of technologies. The regional market opportunity for coal fueled technology orders in the US from 1992 through 2005 is presented

  2. Combined cycles and cogeneration with natural gas and alternative fuels

    International Nuclear Information System (INIS)

    Gusso, R.

    1992-01-01

    Since 1985 there has been a sharp increase world-wide in the sales of gas turbines. The main reasons for this are: the improved designs allowing better gas turbine and, thus, combined cycle efficiencies; the good fuel use indices in the the case of cogeneration; the versatility of the gas turbines even with poly-fuel plants; greatly limited exhaust emissions; and lower manufacturing costs and delivery times with respect to conventional plants. This paper after a brief discussion on the evolution in gas turbine applications in the world and in Italy, assesses their use and environmental impacts with fuels other than natural gas. The paper then reviews Italian efforts to develop power plants incorporating combined cycles and the gasification of coal, residual, and other low calorific value fuels

  3. Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part B

    DEFF Research Database (Denmark)

    La Seta, Angelo; Meroni, Andrea; Andreasen, Jesper Graa

    2016-01-01

    due to the peculiar physical properties of the working fluid and the gas-dynamic phenomena occurring in the machine. Unlike steam Rankine and Brayton engines, organic Rankine cycle expanders combine small enthalpy drops with large expansion ratios. These features yield turbine designs with few highly......Organic Rankine cycle (ORC) power systems have recently emerged as promising solutions for waste heat recovery in low- and medium-size power plants. Their performance and economic feasibility strongly depend on the expander. The design process and efficiency estimation are particularly challenging...... variables affecting the turbine design. Part B of this two-part paper presents the first application of a design method where the thermodynamic cycle optimization is combined with calculations of the maximum expander performance using the mean-line design tool described in part A. The high computational...

  4. Exergy optimization for a novel combination of organic Rankine cycles, Stirling cycle and direct expander turbines

    Science.gov (United States)

    Moghimi, Mahdi; Khosravian, Mohammadreza

    2018-01-01

    In this paper, a novel combination of organic Rankine cycles (ORCs), Stirling cycle and direct expander turbines is modeled and optimized using the genetic algorithm. The Exergy efficiency is considered as an objective function in the genetic algorithm. High efficiency is the main advantage of Stirling cycle, however, it needs nearly isothermal compressor and turbine. Therefore, an argon ORC and a R14 ORC are placed before and after the Striling cycle along with two expander turbines at the end of the line. Each component and cycle of the proposed plant in this article is verified by the previous works available in the literature and good agreement is achieved. The obtained results reveal that 27.98%, 20.86% and 12.90% of the total cold exergy are used by argon ORC, Stirling cycle and R14 ORC, respectively. Therefore, utilization of the Stirling cycle is a good idea for the LNG line cold exergy. The maximum exergy destruction occurs in the heat exchanger after the argon ORC (85.786 kJ/s per one kg/s LNG) due to the wasted cold exergy, which can be used for air conditioning systems in the plant. Finally, it would be shown that the maximum efficiency of the proposed plant is 54.25% and the maximum output power is 355.72 kW.

  5. Combined cycle plants: Yesterday, today, and tomorrow (review)

    Science.gov (United States)

    Ol'khovskii, G. G.

    2016-07-01

    Gas turbine plants (GTP) for a long time have been developed by means of increasing the initial gas temperature and improvement of the turbo-machines aerodynamics and the efficiency of the critical components air cooling within the framework of a simple thermodynamic cycle. The application of watercooling systems that were used in experimental turbines and studied approximately 50 years ago revealed the fundamental difficulties that prevented the practical implementation of such systems in the industrial GTPs. The steam cooling researches have developed more substantially. The 300 MW power GTPs with a closedloop steam cooling, connected in parallel with the intermediate steam heating line in the steam cycle of the combined cycle plant (CCP) have been built, tested, and put into operation. The designs and cycle arrangements of such GTPs and entire combined cycle steam plants have become substantially more complicated without significant economic benefits. As a result, the steam cooling of gas turbines has not become widespread. The cycles—complicated by the intermediate air cooling under compression and reheat of the combustion products under expansion and their heat recovery to raise the combustion chamber entry temperature of the air—were used, in particular, in the domestic power GTPs with a moderate (700-800°C) initial gas turbine entry temperature. At the temperatures being reached to date (1300-1450°C), only one company, Alstom, applies in their 240-300 MW GTPs the recycled fuel cycle under expansion of gases in the turbine. Although these GTPs are reliable, there are no significant advantages in terms of their economy. To make a forecast of the further improvement of power GTPs, a brief review and assessment of the water cooling and steam cooling of hot components and complication of the GTP cycle by the recycling of fuel under expansion of gases in the turbine has been made. It is quite likely in the long term to reach the efficiency for the

  6. Thermodynamic efficiency analysis and cycle optimization of deeply precooled combined cycle engine in the air-breathing mode

    Science.gov (United States)

    Zhang, Jianqiang; Wang, Zhenguo; Li, Qinglian

    2017-09-01

    The efficiency calculation and cycle optimization were carried out for the Synergistic Air-Breathing Rocket Engine (SABRE) with deeply precooled combined cycle. A component-level model was developed for the engine, and exergy efficiency analysis based on the model was carried out. The methods to improve cycle efficiency have been proposed. The results indicate cycle efficiency of SABRE is between 29.7% and 41.7% along the flight trajectory, and most of the wasted exergy is occupied by the unburned hydrogen in exit gas. Exergy loss exists in each engine component, and the sum losses of main combustion chamber(CC), pre-burner(PB), precooler(PC) and 3# heat exchanger(HX3) are greater than 71.3% of the total loss. Equivalence ratio is the main influencing factor of cycle, and it can be regulated by adjusting parameters of helium loop. Increase the maximum helium outlet temperature of PC by 50 K, the total assumption of hydrogen will be saved by 4.8%, and the cycle efficiency is advanced by 3% averagely in the trajectory. Helium recirculation scheme introduces a helium recirculation loop to increase local helium flow rate of PC. It turns out the total assumption of hydrogen will be saved by 9%, that's about 1740 kg, and the cycle efficiency is advanced by 5.6% averagely.

  7. Optimization of advenced liquid natural gas-fuelled combined cycle machinery systems for a high-speed ferry

    DEFF Research Database (Denmark)

    Tveitaskog, Kari Anne; Haglind, Fredrik

    2012-01-01

    This paper is aimed at designing and optimizing combined cycles for marine applications. For this purpose, an in-house numerical simulation tool called DNA (Dynamic Network Analysis) and a genetic algorithm-based optimization routine are used. The top cycle is modeled as the aero-derivative gas....... Furthermore, practical and operational aspects of using these three machinery systems for a high-speed ferry are discussed. Two scenarios are evaluated. The first scenario evaluates the combined cycles with a given power requirement, optimizing the combined cycle while operating the gas turbine at part load....... The second scenario evaluates the combined cycle with the gas turbine operated at full load. For the first scenario, the results suggest that the thermal efficiencies of the combined gas and steam cycles are 46.3 % and 48.2 % for the single pressure and dual pressure steam cycles, respectively. The gas ORC...

  8. Optimised heat recovery steam generators for integrated solar combined cycle plants

    Science.gov (United States)

    Peterseim, Jürgen H.; Huschka, Karsten

    2017-06-01

    The cost of concentrating solar power (CSP) plants is decreasing but, due to the cost differences and the currently limited value of energy storage, implementation of new facilities is still slow compared to photovoltaic systems. One recognized option to lower cost instantly is the hybridization of CSP with other energy sources, such as natural gas or biomass. Various references exist for the combination of CSP with natural gas in combined cycle plants, also known as Integrated Solar Combined Cycle (ISCC) plants. One problem with current ISCC concepts is the so called ISCC crisis, which occurs when CSP is not contributing and cycle efficiency falls below efficiency levels of solely natural gas only fired combined cycle plants. This paper analyses current ISCC concepts and compares them with two optimised designs. The comparison is based on a Kuraymat type ISCC plant and shows that cycle optimization enables a net capacity increase of 1.4% and additional daily generation of up to 7.9%. The specific investment of the optimised Integrated Solar Combined Cycle plant results in a 0.4% cost increase, which is below the additional net capacity and daily generation increase.

  9. Optimal sensor placement in integrated gasification combined cycle power systems

    International Nuclear Information System (INIS)

    Lee, Adrian J.; Diwekar, Urmila M.

    2012-01-01

    Highlights: ► Addresses the sensor placement problem in advanced power system. ► Presents the problem as a stochastic programming problem. ► Considers fisher information based objectives along with the economics of sensor. ► For the first time addresses the problem of sensor placement in advanced power systems. -- Abstract: The optimal sensor placement problem involves determining the most effective locations to place a network of sensors across an array of measurable signals, in accordance with a set of specified objectives and constraints, such as cost, performance, and sensitivity to variations in uncertain environments. In advanced power systems, such as in pulverized coal and integrated gasification combined cycle power plants, the placement of sensors on-line within the power generation process can be expensive or technically infeasible due to certain harsh environments. This paper uses advanced modeling techniques to simulate the system’s steady state behavior, and to capture the variability in unknown process variables using the accuracy information from a given set of online sensors. This variability and measurement error is analyzed using a technique from information theory to determine the most cost-effective network of on-line sensors by formulating a nonlinear, stochastic binary integer problem. The solution is achieved by using an efficient sampling technique, Better Optimization algorithm for Nonlinear Uncertain Systems. The key contribution of using Fisher information as a metric for observation order is that it generalizes the Gaussian assumption on representing process and measurement variability for systems governed by nonlinear dynamics.

  10. All-regime combined-cycle plant: Engineering solutions

    Science.gov (United States)

    Berezinets, P. A.; Tumanovskii, G. G.; Tereshina, G. E.; Krylova, I. N.; Markina, V. N.; Migun, E. N.

    2016-12-01

    The development of distributed power generation systems as a supplement to the centralized unified power grid increases the operational stability and efficiency of the entire power generation industry and improves the power supply to consumers. An all-regime cogeneration combined-cycle plant with a power of 20-25 mW (PGU-20/25T) and an electrical efficiency above 50% has been developed at the All-Russia Thermal Engineering Institute (ATEI) as a distributed power generation object. The PGU-20/25T two-circuit cogeneration plant provides a wide electrical and thermal power adjustment range and the absence of the mutual effect of electrical and thermal power output regimes at controlled frequency and power in a unified or isolated grid. The PGU-20/25T combined-cycle plant incorporates a gas-turbine unit (GTU) with a power of 16 MW, a heat recovery boiler (HRB) with two burners (before the boiler and the last heating stage), and a cogeneration steam turbine with a power of 6/9 MW. The PGU-20/25T plant has a maximum electrical power of 22 MW and an efficiency of 50.8% in the heat recovery regime and a maximum thermal power output of 16.3 MW (14 Gcal/h) in the cogeneration regime. The use of burners can increase the electrical power to 25 MW in the steam condensation regime at an efficiency of 49% and the maximum thermal power output to 29.5 MW (25.4 Gcal/h). When the steam turbine is shut down, the thermal power output can grow to 32.6 MW (28 Gcal/h). The innovative equipment, which was specially developed for PGU-20/25T, improves the reliability of this plant and simplifies its operation. Among this equipment are microflame burners in the heat recovery boiler, a vacuum system based on liquid-ring pumps, and a vacuum deaerator. To enable the application of PGU-20/25T in water-stressed regions, an air condenser preventing the heat-transfer tubes from the risk of covering with ice during operation in frost air has been developed. The vacuum system eliminates the need for

  11. Thermodynamic analysis of heat recovery steam generator in combined cycle power plant

    OpenAIRE

    Ravi Kumar Naradasu; Rama Krishna Konijeti; Sita Rama Raju Venkata Alluru

    2007-01-01

    Combined cycle power plants play an important role in the present energy sector. The main challenge in designing a combined cycle power plant is proper utilization of gas turbine exhaust heat in the steam cycle in order to achieve optimum steam turbine output. Most of the combined cycle developers focused on the gas turbine output and neglected the role of the heat recovery steam generator which strongly affects the overall performance of the combined cycle power plant. The present paper is a...

  12. The Analysis of Initial Parameters of Steam in the Combined-Cycle Plant with High Temperature Gas Turbine

    OpenAIRE

    Uvarov, Artem; Antonova, Aleksandra Mikhailovna; Vorobiev, Aleksandr Vladimirovich

    2015-01-01

    Presents the results of studying the influence of initial steam parameters on the thermal efficiency of double-circuit combined-cycle plant based on a powerful high-temperature gas turbines of the last generation. The advantages of double-circuit combined-cycle plant without reheat in comparison with more complex schemes. Found optimal thermal efficiency values of initial parameters of steam.

  13. Combining the nuclear power plant steam cycle with gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, M.A.; Al Awadhi, Fatimah M.; Bin Amer, Anwar O. [Kuwait Foundation for the Advancement of Sciences, Safat 13113 (Kuwait)

    2010-12-15

    Nuclear steam power plants (NPP) are characterized by low efficiency, compared to steam power plants using fossil fuels. This is due to the relatively low temperature and pressure-throttling conditions of the NPP compared to those using fossil fuel. The light water pressurized water reactor (LW PWR) commercially known as AP600 was suggested for Kuwait cogeneration power desalting plant (CPDP). It has 600 MW nominal power capacity and 33% overall efficiency. Meanwhile, the Kuwaiti Ministry of Electricity and Water (MEW) installed plenty of gas turbines (GTs) to cover the drastic increase in the peak electrical load during the summer season. Combining some of these GTs with the AP600 can increase the capacity and efficiency of the combined plant, compared to either the GT open cycle or the NPP separate plants. This paper investigates the feasibility of utilizing the hot gases leaving the GT to superheat the steam leaving the steam generator of the AP600 NPP, as well as heating the feed water returning to the steam generator of the NPP condenser. This drastically increases the power output and the efficiency of the NPP. Detailed modifications to the NPP power cycle and the resulting enhancement of its performance are presented. (author)

  14. Thermodynamic analysis of combined cycle under design/off-design conditions for its efficient design and operation

    International Nuclear Information System (INIS)

    Zhang, Guoqiang; Zheng, Jiongzhi; Xie, Angjun; Yang, Yongping; Liu, Wenyi

    2016-01-01

    Highlights: • Based on the PG9351FA gas turbine, two gas-steam combined cycles are redesigned. • Analysis of detailed off-design characteristics of the combined cycle main parts. • Suggestions for improving design and operation performance of the combined cycle. • Higher design efficiency has higher off-design efficiency in general PR range. • High pressure ratio combined cycles possess good off-design performance. - Abstract: To achieve a highly efficient design and operation of combined cycles, this study analyzed in detail the off-design characteristics of the main components of three combined cycles with different compressor pressure ratios (PRs) based on real units. The off-design model of combined cycle was built consisting of a compressor, a combustor, a gas turbine, and a heat recovery steam generator (HRSG). The PG9351FA unit is selected as the benchmark unit, on the basis of which the compressor is redesigned with two different PRs. Then, the design/off-design characteristics of the three units with different design PRs and the interactive relations between topping and bottoming cycles are analyzed with the same turbine inlet temperature (TIT). The results show that the off-design characteristics of the topping cycle affect dramatically the combined cycle performance. The variation range of the exergy efficiency of the topping cycle for the three units is between 11.9% and 12.4% under the design/off-design conditions. This range is larger than that of the bottoming cycle (between 9.2% and 9.5%). The HRSG can effectively recycle the heat/heat exergy of the gas turbine exhaust. Comparison among the three units shows that for a traditional gas-steam combined cycle, a high design efficiency results in a high off-design efficiency in the usual PR range. The combined cycle design efficiency of higher pressure ratio is almost equal to that of the PG9351FA, but its off-design efficiency is higher (maximum 0.42%) and the specific power decreases. As for

  15. Thermodynamic assessment of impact of inlet air cooling techniques on gas turbine and combined cycle performance

    International Nuclear Information System (INIS)

    Mohapatra, Alok Ku; Sanjay

    2014-01-01

    The article is focused on the comparison of impact of two different methods of inlet air cooling (vapor compression and vapor absorption cooling) integrated to a cooled gas turbine based combined cycle plant. Air-film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor pressure ratio, compressor inlet temperature (T i , C ), turbine inlet temperature (T i , T ), ambient relative humidity and ambient temperature on performance parameters of plant has been carried out. Optimum T i , T corresponding to maximum plant efficiency of combined cycle increases by 100 °C due to the integration of inlet air cooling. It has been observed that vapor compression cooling improves the efficiency of gas turbine cycle by 4.88% and work output by 14.77%. In case of vapor absorption cooling an improvement of 17.2% in gas cycle work output and 9.47% in gas cycle efficiency has been observed. For combined cycle configuration, however, vapor compression cooling should be preferred over absorption cooling in terms of higher plant performance. The optimum value of compressor inlet temperature has been observed to be 20 °C for the chosen set of conditions for both the inlet air cooling schemes. - Highlights: • Inlet air cooling improves performance of cooled gas turbine based combined cycle. • Vapor compression inlet air cooling is superior to vapor absorption inlet cooling. • For every turbine inlet temperature, there exists an optimum pressure ratio. • The optimum compressor inlet temperature is found to be 293 K

  16. Exergoeconomical analysis of coal gasification combined cycle power plants

    International Nuclear Information System (INIS)

    Avgousti, A.; Knoche, K.F.; Poptodorov, H.; Hesselmann, K.; Roth, M.

    1989-01-01

    This paper reports on combined cycle power plants with integrated coal gasification for a better utilization of primary energy sources which gained more and more importance. The established coal gasification technology offers various possibilities e.g. the TEXACO or the PRENFLO method. Recommendation for processes with these gasification methods will be evaluated energetically and exergetically. The pure thermodynamical analysis is at a considerable disadvantage in that the economical consequences of certain process improvement measures are not subjected to investigation. The connection of the exergetical with the economical evaluation will be realized in a way suggested as exergoeconomical analysis. This consideration of the reciprocal influencing of the exergy destruction and the capital depending costs is resulting in an optimization of the process and a minimization of the product costs

  17. Combined Cycle Power Generation Employing Pressure Gain Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Holley, Adam [United Technologies Corporation, East Hartford, CT (United States). Research Center

    2017-05-15

    The Phase I program assessed the potential benefit of applying pressure gain combustion (PGC) technology to a natural gas combined cycle power plant. A conceptual design of the PGC integrated gas turbine was generated which was simulated in a detailed system modeling tool. The PGC integrated system was 1.93% more efficient, produced 3.09% more power, and reduced COE by 0.58%. Since the PGC system used had the same fuel flow rate as the baseline system, it also reduced CO2 emissions by 3.09%. The PGC system did produce more NOx than standard systems, but even with the performanceand cost penalties associated with the cleanup system it is better in every measure. This technology benefits all of DOE’s stated program goals to improve plant efficiency, reduce CO2 production, and reduce COE.

  18. Gasification integrated to combined cycles; Gasificacion integrada a ciclos combinados

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez M, Manuel F; Alcaraz C, Agustin M [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2001-07-01

    The mineral coal is one of the most abundant fuels in the planet, but it has important amounts of sulfur and ashes that make difficult their use. On the other hand, many countries at the present time prevent to use the fuel oil as combustible with conventional technologies due to the metal and sulfur contents. Finally, in the new schemes of oil refinement it is anticipated to use the coking to take advantage of the barrel bottoms. The remainder product of this process, known as refinery coke, has a low commercial value, a high calorific power and high sulfur content and metals. The gasification has been developed in the last the two decades, in the highly industrialized countries, as an alternative for the efficient and clean generation of electricity from dirty fuels, as well as for obtaining certain fuels in places where access to petroleum is not available, but to the coal. This technology fulfills the strictest regulations of the world in what polluting emissions refers and it is the only solution, next to the fluidized beds, for the problems that present some fuels that are difficult to burn with conventional technologies, as the mineral coal, the petroleum coke and even the liquid remainders of the refinement. With base in the former, it is possible to think about the integration of this technology to a combined cycle plant for the generation of electricity or to a refinery generating steam, electrical energy, hydrogen and other consumables at a competitive cost, in such a way that the problems of handling and storage of the remainders are solved; on the other hand the use of the primary power resources in the country is maximized. [Spanish] El carbon mineral es uno de los combustibles mas abundantes en el planeta, pero posee cantidades importantes de azufre y cenizas que dificultan su utilizacion. Por otra parte, muchos paises en la actualidad impiden utilizar el combustoleo como combustible para tecnologias convencionales debido a los contenidos de azufre y

  19. Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part A: Turbine Model

    Directory of Open Access Journals (Sweden)

    Andrea Meroni

    2016-04-01

    Full Text Available Axial-flow turbines represent a well-established technology for a wide variety of power generation systems. Compactness, flexibility, reliability and high efficiency have been key factors for the extensive use of axial turbines in conventional power plants and, in the last decades, in organic Rankine cycle power systems. In this two-part paper, an overall cycle model and a model of an axial turbine were combined in order to provide a comprehensive preliminary design of the organic Rankine cycle unit, taking into account both cycle and turbine optimal designs. Part A presents the preliminary turbine design model, the details of the validation and a sensitivity analysis on the main parameters, in order to minimize the number of decision variables in the subsequent turbine design optimization. Part B analyzes the application of the combined turbine and cycle designs on a selected case study, which was performed in order to show the advantages of the adopted methodology. Part A presents a one-dimensional turbine model and the results of the validation using two experimental test cases from literature. The first case is a subsonic turbine operated with air and investigated at the University of Hannover. The second case is a small, supersonic turbine operated with an organic fluid and investigated by Verneau. In the first case, the results of the turbine model are also compared to those obtained using computational fluid dynamics simulations. The results of the validation suggest that the model can predict values of efficiency within ± 1.3%-points, which is in agreement with the reliability of classic turbine loss models such as the Craig and Cox correlations used in the present study. Values similar to computational fluid dynamics simulations at the midspan were obtained in the first case of validation. Discrepancy below 12 % was obtained in the estimation of the flow velocities and turbine geometry. The values are considered to be within a

  20. Optimum operating conditions for a combined power and cooling thermodynamic cycle

    International Nuclear Information System (INIS)

    Sadrameli, S.M.; Goswami, D.Y.

    2007-01-01

    The combined production of thermal power and cooling with an ammonia-water based cycle proposed by Goswami is under intensive investigation. In the cycle under consideration, simultaneous cooling output is produced by expanding an ammonia-rich vapor in an expander to sub-ambient temperatures and subsequently heating the cool exhaust. When this mechanism for cooling production is considered in detail, it is apparent that the cooling comes at some expense to work production. To optimize this trade-off, a very specific coefficient-of-performance has been defined. In this paper, the simulation of the cycle was carried out in the process simulator ASPEN Plus. The optimum operating conditions have been found by using the Equation Oriented mode of the simulator and some of the results have been compared with the experimental data obtained from the cycle. The agreement between the two sets proves the accuracy of the optimization results

  1. INTEGRATED GASIFICATION COMBINED CYCLE PROJECT 2 MW FUEL CELL DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    FuelCell Energy

    2005-05-16

    With about 50% of power generation in the United States derived from coal and projections indicating that coal will continue to be the primary fuel for power generation in the next two decades, the Department of Energy (DOE) Clean Coal Technology Demonstration Program (CCTDP) has been conducted since 1985 to develop innovative, environmentally friendly processes for the world energy market place. The 2 MW Fuel Cell Demonstration was part of the Kentucky Pioneer Energy (KPE) Integrated Gasification Combined Cycle (IGCC) project selected by DOE under Round Five of the Clean Coal Technology Demonstration Program. The participant in the CCTDP V Project was Kentucky Pioneer Energy for the IGCC plant. FuelCell Energy, Inc. (FCE), under subcontract to KPE, was responsible for the design, construction and operation of the 2 MW fuel cell power plant. Duke Fluor Daniel provided engineering design and procurement support for the balance-of-plant skids. Colt Engineering Corporation provided engineering design, fabrication and procurement of the syngas processing skids. Jacobs Applied Technology provided the fabrication of the fuel cell module vessels. Wabash River Energy Ltd (WREL) provided the test site. The 2 MW fuel cell power plant utilizes FuelCell Energy's Direct Fuel Cell (DFC) technology, which is based on the internally reforming carbonate fuel cell. This plant is capable of operating on coal-derived syngas as well as natural gas. Prior testing (1992) of a subscale 20 kW carbonate fuel cell stack at the Louisiana Gasification Technology Inc. (LGTI) site using the Dow/Destec gasification plant indicated that operation on coal derived gas provided normal performance and stable operation. Duke Fluor Daniel and FuelCell Energy developed a commercial plant design for the 2 MW fuel cell. The plant was designed to be modular, factory assembled and truck shippable to the site. Five balance-of-plant skids incorporating fuel processing, anode gas oxidation, heat recovery

  2. Thermodynamic analysis of a novel integrated solar combined cycle

    International Nuclear Information System (INIS)

    Li, Yuanyuan; Yang, Yongping

    2014-01-01

    Highlights: • A novel ISCC scheme with two-stage DSG fields has been proposed and analyzed. • HRSG and steam turbine working parameters have been optimized to match the solar integration. • New scheme exhibits higher solar shares in the power output and solar-to-electricity efficiency. • Thermodynamic performances between new and reference systems have been investigated and compared. - Abstract: Integrated solar combined cycle (ISCC) systems have become more and more popular due to their high fuel and solar energy utilization efficiencies. Conventional ISCC systems with direct steam generation (DSG) have only one-stage solar input. A novel ISCC with DSG system has been proposed and analyzed in this paper. The new system consists two-stage solar input, which would significantly increase solar share in the total power output. Moreover, how and where solar energy is input into ISCC system would have impact on the solar and system overall efficiencies, which have been analyzed in the paper. It has been found that using solar heat to supply latent heat for vaporization of feedwater would be superior to that to be used for sensible heating purposes (e.g. Superheating steam). The study shows that: (1) producing both the high- and low-pressure saturated steam in the DSG trough collector could be an efficient way to improve process and system performance; (2) for a given live steam pressure, the optimum secondary and reheat steam conditions could be matched to reach the highest system thermal efficiency and net solar-to-electricity efficiency; (3) the net solar-to-electricity efficiency could reach up to 30% in the novel two-stage ISCC system, higher than that in the one-stage ISCC power plant; (4) compared with the conventional combined cycle gas turbine (CCGT) power system, lower stack temperature could be achieved, owing to the elimination of the approach-temperature-difference constraint, resulting in better thermal match in the heat recovery steam generator

  3. Efficiency Growth of Combined-cycle Cogeneration Plant with the Heat Supply System

    Directory of Open Access Journals (Sweden)

    Denysova Alla

    2015-08-01

    Full Text Available Energy efficiency of modern technologies of the combined production of heat and electricity and ways of energy saving on base of recycling secondary energy sources has been estimated. It is shown that the most effective for cogeneration are combined-cycle plants. The rational scheme of interaction of combined-cycle cogeneration plant with heat supply system has been offered. Theoretical bases of interaction of main installation with a contour of heat and hot water supply system has been developed. Numerical modeling of temperature parameters and the analysis of results of numerical modeling has been executed. The technology of increase of energy efficiency of installations on base of recycling heat is offered. Increase of effectiveness of system is achieved due to full use of heat and reduction of losses to environment. It is established, that the rational scheme of interaction of combined-cycle cogeneration plant with heat supply system allows increasing energy efficiency on 2 % that corresponds to economy of fuel 3 %.

  4. Model Predictive Control of Integrated Gasification Combined Cycle Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    B. Wayne Bequette; Priyadarshi Mahapatra

    2010-08-31

    The primary project objectives were to understand how the process design of an integrated gasification combined cycle (IGCC) power plant affects the dynamic operability and controllability of the process. Steady-state and dynamic simulation models were developed to predict the process behavior during typical transients that occur in plant operation. Advanced control strategies were developed to improve the ability of the process to follow changes in the power load demand, and to improve performance during transitions between power levels. Another objective of the proposed work was to educate graduate and undergraduate students in the application of process systems and control to coal technology. Educational materials were developed for use in engineering courses to further broaden this exposure to many students. ASPENTECH software was used to perform steady-state and dynamic simulations of an IGCC power plant. Linear systems analysis techniques were used to assess the steady-state and dynamic operability of the power plant under various plant operating conditions. Model predictive control (MPC) strategies were developed to improve the dynamic operation of the power plants. MATLAB and SIMULINK software were used for systems analysis and control system design, and the SIMULINK functionality in ASPEN DYNAMICS was used to test the control strategies on the simulated process. Project funds were used to support a Ph.D. student to receive education and training in coal technology and the application of modeling and simulation techniques.

  5. Parametric analysis for a new combined power and ejector-absorption refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Jiangfeng; Dai Yiping; Zhang Taiyong; Ma Shaolin

    2009-01-01

    A new combined power and ejector-absorption refrigeration cycle is proposed, which combines the Rankine cycle and the ejector-absorption refrigeration cycle, and could produce both power output and refrigeration output simultaneously. This combined cycle, which originates from the cycle proposed by authors previously, introduces an ejector between the rectifier and the condenser, and provides a performance improvement without greatly increasing the complexity of the system. A parametric analysis is conducted to evaluate the effects of the key thermodynamic parameters on the cycle performance. It is shown that heat source temperature, condenser temperature, evaporator temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. It is evident that the ejector can improve the performance of the combined cycle proposed by authors previously.

  6. Pre-Combustion Carbondioxide Capture in Integrated Gasification Combined Cycles

    Directory of Open Access Journals (Sweden)

    M. Zeki YILMAZOĞLU

    2010-02-01

    Full Text Available Thermal power plants have a significant place big proportion in the production of electric energy. Thermal power plants are the systems which converts heat energy to mechanical energy and also mechanical energy to electrical energy. Heat energy is obtained from combustion process and as a result of this, some harmful emissions, like CO2, which are the reason for global warming, are released to atmosphere. The contribution of carbondioxide to global warming has been exposed by the previous researchs. Due to this fact, clean energy technologies are growing rapidly all around the world. Coal is generally used in power plants and when compared to other fossil energy sources unit electricity production cost is less than others. When reserve rate is taken into account, coal may be converted to energy in a more efficient and cleaner way. The aim for using the clean coal technologies are to eradicate the harmful emissions of coal and to store the carbondioxide, orginated from combustion, in different forms. In line with this aim, carbondioxide may be captured by either pre-combustion, by O2/CO2 recycling combustion systems or by post combustion. The integrated gasification combined cycles (IGCC are available in pre-combustion capture systems, whereas in O2/CO2 recycling combustion systems there are ultrasuper critical boiler technologies and finally flue gas washing systems by amines exists in post combustion systems. In this study, a pre-combustion CO2 capture process via oxygen blown gasifiers is compared with a conventional power plant in terms of CO2 emissions. Captured carbondioxide quantity has been presented as a result of the calculations made throughout the study.

  7. Optimization of fog inlet air cooling system for combined cycle power plants using genetic algorithm

    International Nuclear Information System (INIS)

    Ehyaei, Mehdi A.; Tahani, Mojtaba; Ahmadi, Pouria; Esfandiari, Mohammad

    2015-01-01

    In this research paper, a comprehensive thermodynamic modeling of a combined cycle power plant is first conducted and the effects of gas turbine inlet fogging system on the first and second law efficiencies and net power outputs of combined cycle power plants are investigated. The combined cycle power plant (CCPP) considered for this study consist of a double pressure heat recovery steam generator (HRSG) to utilize the energy of exhaust leaving the gas turbine and produce superheated steam to generate electricity in the Rankine cycle. In order to enhance understanding of this research and come up with optimum performance assessment of the plant, a complete optimization is using a genetic algorithm conducted. In order to achieve this goal, a new objective function is defined for the system optimization including social cost of air pollution for the power generation systems. The objective function is based on the first law efficiency, energy cost and the external social cost of air pollution for an operational system. It is concluded that using inlet air cooling system for the CCPP system and its optimization results in an increase in the average output power, first and second law efficiencies by 17.24%, 3.6% and 3.5%, respectively, for three warm months of year. - Highlights: • To model the combined cycle power plant equipped with fog inlet air cooling method. • To conduct both exergy and economic analyses for better understanding. • To conduct a complete optimization using a genetic algorithm to determine the optimal design parameters of the system

  8. ECONOMICAL OPTIMIZATION MODEL OF CONDENSING PLANTS CAPACITY MODERNIZED BY COMBINED-CYCLE TECHNOLOGY

    OpenAIRE

    S. G. Morozov

    2009-01-01

    Economic evaluation of combined-cycle technologies as main direction of power industry development is considered in the article. Analysis of Belarusian energy system operating mode is carried out. Economical optimization model of condensing plants capacity modernized by combined-cycle technology is suggested. In accordance with author’s approach optimal value of thermal power station modernization by combined-cycle technology is defined on basis of minimum-cost criterion. It is argued that in...

  9. ECONOMICAL OPTIMIZATION MODEL OF CONDENSING PLANTS CAPACITY MODERNIZED BY COMBINED-CYCLE TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    S. G. Morozov

    2009-01-01

    Full Text Available Economic evaluation of combined-cycle technologies as main direction of power industry development is considered in the article. Analysis of Belarusian energy system operating mode is carried out. Economical optimization model of condensing plants capacity modernized by combined-cycle technology is suggested. In accordance with author’s approach optimal value of thermal power station modernization by combined-cycle technology is defined on basis of minimum-cost criterion. It is argued that in the medium-term period power station modernization on basis of combined-cycle plant is most effective direction of energy-supply system technological development.

  10. Economic optimization of the combined cycle integrated with multi-product gasification system

    International Nuclear Information System (INIS)

    Liszka, M.; Ziebik, A.

    2009-01-01

    The system taken into consideration consists of the Corex unit, combined cycle power plant and air separation unit (ASU). The Corex process (trademark of Siemens-VAI) is one of technologies for cokeless hot metal production. Coal is gasified by oxygen in the hot metal environment. The excess gas can be used out of installation. It has been assumed that the Corex export gas is fired in combined cycle. The gas turbine (GT) structure was assumed as a fixed simple cycle while the heat recovery steam generator (HRSG) and steam turbine arrangements are free for optimization. The examples of independent variables selected for optimization are number of HRSG pressure levels, GT pressure ratio, minimal temperature differences in HRSG, flow rate of compressed air form GT compressor to ASU. Finally, 16 independent variables have been qualified for optimization. The synthesis optimization is based on the superstructure method. The economic net present value (NPV) has been chosen as the objective function. All power plant facilities have been modeled on the GateCycle software. The off-design models include, among others, the GT blade cooling and HRSG heat transfer coefficient analyses. Two optimization methods - genetic algorithm and Powells conjugate directions have been coupled in one hybrid procedure. The whole optimization analysis has been repeated several times for different price scenarios on the coal, iron and electricity markets

  11. Parametric analysis and optimization for a combined power and refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Jiangfeng; Dai Yiping; Gao Lin

    2008-01-01

    A combined power and refrigeration cycle is proposed, which combines the Rankine cycle and the absorption refrigeration cycle. This combined cycle uses a binary ammonia-water mixture as the working fluid and produces both power output and refrigeration output simultaneously with only one heat source. A parametric analysis is conducted to evaluate the effects of thermodynamic parameters on the performance of the combined cycle. It is shown that heat source temperature, environment temperature, refrigeration temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. A parameter optimization is achieved by means of genetic algorithm to reach the maximum exergy efficiency. The optimized exergy efficiency is 43.06% under the given condition

  12. Simulation of an integrated gasification combined cycle with chemical-looping combustion and carbon dioxide sequestration

    International Nuclear Information System (INIS)

    Jiménez Álvaro, Ángel; López Paniagua, Ignacio; González Fernández, Celina; Rodríguez Martín, Javier; Nieto Carlier, Rafael

    2015-01-01

    Highlights: • A chemical-looping combustion based integrated gasification combined cycle is simulated. • The energetic performance of the plant is analyzed. • Different hydrogen-content synthesis gases are under study. • Energy savings accounting carbon dioxide sequestration and storage are quantified. • A notable increase on thermal efficiency up to 7% is found. - Abstract: Chemical-looping combustion is an interesting technique that makes it possible to integrate power generation from fuels combustion and sequestration of carbon dioxide without energy penalty. In addition, the combustion chemical reaction occurs with a lower irreversibility compared to a conventional combustion, leading to attain a somewhat higher overall thermal efficiency in gas turbine systems. This paper provides results about the energetic performance of an integrated gasification combined cycle power plant based on chemical-looping combustion of synthesis gas. A real understanding of the behavior of this concept of power plant implies a complete thermodynamic analysis, involving several interrelated aspects as the integration of energy flows between the gasifier and the combined cycle, the restrictions in relation with heat balances and chemical equilibrium in reactors and the performance of the gas turbines and the downstream steam cycle. An accurate thermodynamic modeling is required for the optimization of several design parameters. Simulations to evaluate the energetic efficiency of this chemical-looping-combustion based power plant under diverse working conditions have been carried out, and a comparison with a conventional integrated gasification power plant with precombustion capture of carbon dioxide has been made. Two different synthesis gas compositions have been tried to check its influence on the results. The energy saved in carbon capture and storage is found to be significant and even notable, inducing an improvement of the overall power plant thermal efficiency of

  13. Thermodynamic analysis of engineering solutions aimed at raising the efficiency of integrated gasification combined cycle

    Science.gov (United States)

    Gordeev, S. I.; Bogatova, T. F.; Ryzhkov, A. F.

    2017-11-01

    Raising the efficiency and environmental friendliness of electric power generation from coal is the aim of numerous research groups today. The traditional approach based on the steam power cycle has reached its efficiency limit, prompted by materials development and maneuverability performance. The rival approach based on the combined cycle is also drawing nearer to its efficiency limit. However, there is a reserve for efficiency increase of the integrated gasification combined cycle, which has the energy efficiency at the level of modern steam-turbine power units. The limit of increase in efficiency is the efficiency of NGCC. One of the main problems of the IGCC is higher costs of receiving and preparing fuel gas for GTU. It would be reasonable to decrease the necessary amount of fuel gas in the power unit to minimize the costs. The effect can be reached by raising of the heat value of fuel gas, its heat content and the heat content of cycle air. On the example of the process flowsheet of the IGCC with a power of 500 MW, running on Kuznetsk bituminous coal, by means of software Thermoflex, the influence of the developed technical solutions on the efficiency of the power plant is considered. It is received that rise in steam-air blast temperature to 900°C leads to an increase in conversion efficiency up to 84.2%. An increase in temperature levels of fuel gas clean-up to 900°C leads to an increase in the IGCC efficiency gross/net by 3.42%. Cycle air heating reduces the need for fuel gas by 40% and raises the IGCC efficiency gross/net by 0.85-1.22%. The offered solutions for IGCC allow to exceed net efficiency of analogous plants by 1.8-2.3%.

  14. THERMODYNAMIC ANALYSIS AND SIMULATION OF A NEW COMBINED POWER AND REFRIGERATION CYCLE USING ARTIFICIAL NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    Hossein Rezvantalab

    2011-01-01

    Full Text Available In this study, a new combined power and refrigeration cycle is proposed, which combines the Rankine and absorption refrigeration cycles. Using a binary ammonia-water mixture as the working fluid, this combined cycle produces both power and refrigeration output simultaneously by employing only one external heat source. In order to achieve the highest possible exergy efficiency, a secondary turbine is inserted to expand the hot weak solution leaving the boiler. Moreover, an artificial neural network (ANN is used to simulate the thermodynamic properties and the relationship between the input thermodynamic variables on the cycle performance. It is shown that turbine inlet pressure, as well as heat source and refrigeration temperatures have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. In addition, the results of ANN are in excellent agreement with the mathematical simulation and cover a wider range for evaluation of cycle performance.

  15. A Thermodynamic Analysis of Two Competing Mid-Sized Oxyfuel Combustion Combined Cycles

    Directory of Open Access Journals (Sweden)

    Egill Thorbergsson

    2016-01-01

    Full Text Available A comparative analysis of two mid-sized oxyfuel combustion combined cycles is performed. The two cycles are the semiclosed oxyfuel combustion combined cycle (SCOC-CC and the Graz cycle. In addition, a reference cycle was established as the basis for the analysis of the oxyfuel combustion cycles. A parametric study was conducted where the pressure ratio and the turbine entry temperature were varied. The layout and the design of the SCOC-CC are considerably simpler than the Graz cycle while it achieves the same net efficiency as the Graz cycle. The fact that the efficiencies for the two cycles are close to identical differs from previously reported work. Earlier studies have reported around a 3% points advantage in efficiency for the Graz cycle, which is attributed to the use of a second bottoming cycle. This additional feature is omitted to make the two cycles more comparable in terms of complexity. The Graz cycle has substantially lower pressure ratio at the optimum efficiency and has much higher power density for the gas turbine than both the reference cycle and the SCOC-CC.

  16. Effectiveness of cooling production with a combined power and cooling thermodynamic cycle

    International Nuclear Information System (INIS)

    Martin, C.; Goswami, D.Y.

    2006-01-01

    The combined production of power and cooling with an ammonia-water based cycle is under investigation. Cooling is produced by expanding an ammonia-rich vapor in an expander to sub-ambient temperatures and it is shown that a compromise exists between cooling and work production. A new parameter, termed the effective COP, is used to relate the gain in cooling to the compromise in work production. When the parameter is used to optimize conditions for the rectifier, the effective COP values are good, having values of up to 5. However, when combined operation is compared to work-optimized results, the maximum effective COP values are near 1.1. This implies that per unit of cooling production, nearly equal amounts of work are compromised for combined operation

  17. System concept for FBR cycle data base

    International Nuclear Information System (INIS)

    Kofuji, Hirohide; Saigusa, Toshiie; Hirao, Kazunori

    2000-03-01

    Accompanying with the progress of the 'Feasibility Study on FBR cycle system; FS', various kinds of technical information, facility design parameters, and related data will be obtained and they should be stored in data bases and be used as fundamental data for the FS. So the several data bases are going to be set up at each section and controlled by the management system through a local area network. Among above data bases, a prototype of FBR cycle data base that will record data for FBR scenario study and synthetic assessment is to be completed in Phase I by fiscal year 2000, so the data base system concept has been examined in the current fiscal year, 1999. As the results of the system concept examination, two types of prototypes have been selected, one is to be set up as the data table containing digital data that are extracted from technical papers, another is as image data of papers with index information. Referring to examples of data bases in other companies, it was kept in mind to use a package software for general purpose and to utilize data existing now. (author)

  18. Combined Rankin and Organic Rankin Cycles with Screw Expenders

    OpenAIRE

    Tang, Yan

    2014-01-01

    Low pressure saturated steam exists in a lot of industries. The recovery of the energy from the low pressure saturated steam can save tremendous power consumption for those industries. Although the Rankin cycle with a steam turbine can be used to generate the power from the low pressure saturated steam, the isotropic efficiency of the steam turbine is low, the reliability is questionable due to the two phase expansion, and the size is typically large due to the low pressure. This paper presen...

  19. Carbon exergy tax applied to biomass integrated gasification combined cycle in sugarcane industry

    International Nuclear Information System (INIS)

    Fonseca Filho, Valdi Freire da; Matelli, José Alexandre; Perrella Balestieri, José Antonio

    2016-01-01

    The development of technologies based on energy renewable sources is increasing worldwide in order to diversify the energy mix and satisfy the rigorous environmental legislation and international agreements to reduce pollutant emission. Considering specific characteristics of biofuels available in Brazil, studies regarding such technologies should be carried out aiming energy mix diversification. Several technologies for power generation from biomass have been presented in the technical literature, and plants with BIGCC (biomass integrated gasification combined cycle) emerge as a major technological innovation. By obtaining a fuel rich in hydrogen from solid biomass gasification, BIGCC presents higher overall process efficiency than direct burning of the solid fuel in conventional boilers. The objective of this paper is to develop a thermodynamic and chemical equilibrium model of a BIGCC configuration for sugarcane bagasse. The model embodies exergetic cost and CO 2 emission analyses through the method of CET (carbon exergy tax). An exergetic penalty comparison between the BIGCC technology (with and without CO 2 capture and sequestration), a natural gas combined cycle and the traditional steam cycle of sugarcane sector is then presented. It is verified that the BIGCC configuration with CO 2 capture and sequestration presents technical and environmental advantages when compared to traditional technology. - Highlights: • We compared thermal cycles with the exergetic carbon exergy tax. • Thermal cycles with and without carbon capture and sequestration were considered. • Burned and gasified sugarcane bagasse was assumed as renewable fuel. • Exergetic carbon penalty tax was imposed to all studied configurations. • BIGCC with carbon sequestration revealed to be advantageous.

  20. Numerical optimization of Combined Heat and Power Organic Rankine Cycles – Part A: Design optimization

    International Nuclear Information System (INIS)

    Martelli, Emanuele; Capra, Federico; Consonni, Stefano

    2015-01-01

    This two-part paper proposes an approach based on state-of-the-art numerical optimization methods for simultaneously determining the most profitable design and part-load operation of Combined Heat and Power Organic Rankine Cycles. Compared to the usual design practice, the important advantages of the proposed approach are (i) to consider the part-load performance of the ORC at the design stage, (ii) to optimize not only the cycle variables, but also the main turbine design variables (number of stages, stage loads, rotational speed). In this first part (Part A), the design model and the optimization algorithm are presented and tested on a real-world test case. PGS-COM, a recently proposed hybrid derivative-free algorithm, allows to efficiently tackle the challenging non-smooth black-box problem. - Highlights: • Algorithm for the simultaneous optimization Organic Rakine Cycle and turbine. • Thermodynamic and economic models of boiler, cycle, turbine are developed. • Non-smooth black-box optimization problem is successfully tackled with PGS-COM. • Test cases show that the algorithm returns optimal solutions within 4 min. • Toluene outperforms MDM (a siloxane) in terms of efficiency and costs.

  1. Combined cycle solar central receiver hybrid power system study. Final technical report. Volume II

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-11-01

    This study develops the conceptual design for a commercial-scale (nominal 100 MWe) central receiver solar/fossil fuel hybrid power system with combined cycle energy conversion. A near-term, metallic heat pipe receiver and an advanced ceramic tube receiver hybrid system are defined through parametric and market potential analyses. Comparative evaluations of the cost of power generation, the fuel displacement potential, and the technological readiness of these two systems indicate that the near-term hybrid system has better potential for commercialization by 1990. Based on the assessment of the conceptual design, major cost and performance improvements are projected for the near-term system. Constraints preventing wide-spread use were not identified. Energy storage is not required for this system and analyses show no economic advantages with energy storage provisions. It is concluded that the solar hybrid system is a cost effective alternative to conventional gas turbines and combined cycle generating plants, and has potential for intermediate-load market penetration at 15% annual fuel escalation rate. Due to their flexibility, simple solar/nonsolar interfacing, and short startup cycles, these hybrid plants have significant operating advantages. Utility company comments suggest that hybrid power systems will precede stand-alone solar plants.

  2. Innovative open air brayton combined cycle systems for the next generation nuclear power plants

    Science.gov (United States)

    Zohuri, Bahman

    The purpose of this research was to model and analyze a nuclear heated multi-turbine power conversion system operating with atmospheric air as the working fluid. The air is heated by a molten salt, or liquid metal, to gas heat exchanger reaching a peak temperature of 660 0C. The effects of adding a recuperator or a bottoming steam cycle have been addressed. The calculated results are intended to identify paths for future work on the next generation nuclear power plant (GEN-IV). This document describes the proposed system in sufficient detail to communicate a good understanding of the overall system, its components, and intended uses. The architecture is described at the conceptual level, and does not replace a detailed design document. The main part of the study focused on a Brayton --- Rankine Combined Cycle system and a Recuperated Brayton Cycle since they offer the highest overall efficiencies. Open Air Brayton power cycles also require low cooling water flows relative to other power cycles. Although the Recuperated Brayton Cycle achieves an overall efficiency slightly less that the Brayton --- Rankine Combined Cycle, it is completely free of a circulating water system and can be used in a desert climate. Detailed results of modeling a combined cycle Brayton-Rankine power conversion system are presented. The Rankine bottoming cycle appears to offer a slight efficiency advantage over the recuperated Brayton cycle. Both offer very significant advantages over current generation Light Water Reactor steam cycles. The combined cycle was optimized as a unit and lower pressure Rankine systems seem to be more efficient. The combined cycle requires a lot less circulating water than current power plants. The open-air Brayton systems appear to be worth investigating, if the higher temperatures predicted for the Next Generation Nuclear Plant do materialize.

  3. BrainCycles: Experimental Setup for the Combined Measurement of Cortical and Subcortical Activity in Parkinson's Disease Patients during Cycling

    Science.gov (United States)

    Gratkowski, Maciej; Storzer, Lena; Butz, Markus; Schnitzler, Alfons; Saupe, Dietmar; Dalal, Sarang S.

    2017-01-01

    Recently, it has been demonstrated that bicycling ability remains surprisingly preserved in Parkinson's disease (PD) patients who suffer from freezing of gait. Cycling has been also proposed as a therapeutic means of treating PD symptoms, with some preliminary success. The neural mechanisms behind these phenomena are however not yet understood. One of the reasons is that the investigations of neuronal activity during pedaling have been up to now limited to PET and fMRI studies, which restrict the temporal resolution of analysis, and to scalp EEG focused on cortical activation. However, deeper brain structures like the basal ganglia are also associated with control of voluntary motor movements like cycling and are affected by PD. Deep brain stimulation (DBS) electrodes implanted for therapy in PD patients provide rare and unique access to directly record basal ganglia activity with a very high temporal resolution. In this paper we present an experimental setup allowing combined investigation of basal ganglia local field potentials (LFPs) and scalp EEG underlying bicycling in PD patients. The main part of the setup is a bike simulator consisting of a classic Dutch-style bicycle frame mounted on a commercially available ergometer. The pedal resistance is controllable in real-time by custom software and the pedal position is continuously tracked by custom Arduino-based electronics using optical and magnetic sensors. A portable bioamplifier records the pedal position signal, the angle of the knee, and the foot pressure together with EEG, EMG, and basal ganglia LFPs. A handlebar-mounted display provides additional information for patients riding the bike simulator, including the current and target pedaling rate. In order to demonstrate the utility of the setup, example data from pilot recordings are shown. The presented experimental setup provides means to directly record basal ganglia activity not only during cycling but also during other movement tasks in patients who

  4. Dynamic Testing of the NASA Hypersonic Project Combined Cycle Engine Testbed for Mode Transition Experiments

    Science.gov (United States)

    2011-01-01

    NASA is interested in developing technology that leads to more routine, safe, and affordable access to space. Access to space using airbreathing propulsion systems has potential to meet these objectives based on Airbreathing Access to Space (AAS) system studies. To this end, the NASA Fundamental Aeronautics Program (FAP) Hypersonic Project is conducting fundamental research on a Turbine Based Combined Cycle (TBCC) propulsion system. The TBCC being studied considers a dual flow-path inlet system. One flow-path includes variable geometry to regulate airflow to a turbine engine cycle. The turbine cycle provides propulsion from take-off to supersonic flight. The second flow-path supports a dual-mode scramjet (DMSJ) cycle which would be initiated at supersonic speed to further accelerate the vehicle to hypersonic speed. For a TBCC propulsion system to accelerate a vehicle from supersonic to hypersonic speed, a critical enabling technology is the ability to safely and effectively transition from the turbine to the DMSJ-referred to as mode transition. To experimentally test methods of mode transition, a Combined Cycle Engine (CCE) Large-scale Inlet testbed was designed with two flow paths-a low speed flow-path sized for a turbine cycle and a high speed flow-path designed for a DMSJ. This testbed system is identified as the CCE Large-Scale Inlet for Mode Transition studies (CCE-LIMX). The test plan for the CCE-LIMX in the NASA Glenn Research Center (GRC) 10- by 10-ft Supersonic Wind Tunnel (10x10 SWT) is segmented into multiple phases. The first phase is a matrix of inlet characterization (IC) tests to evaluate the inlet performance and establish the mode transition schedule. The second phase is a matrix of dynamic system identification (SysID) experiments designed to support closed-loop control development at mode transition schedule operating points for the CCE-LIMX. The third phase includes a direct demonstration of controlled mode transition using a closed loop control

  5. The application of cycling and cycling combined with feedback in the rehabilitation of stroke patients: a review.

    Science.gov (United States)

    Barbosa, David; Santos, Cristina P; Martins, Maria

    2015-02-01

    Stroke is a leading cause of long-term disabilities, such as hemiparesis, inability to walk without assistance, and dependence of others in the activities of daily living. Motor function rehabilitation after stroke demands for methods oriented to the recovery of the walking capacity. Because of the similarities with walking, cycling leg exercise may present a solution to this problem. The aim of this article is to review the state of the art applications of cycling leg exercise as a (1) motor function rehabilitation method and an (2) aerobic training method for stroke patients as well as the commonly used (3) assessment tools. The cycling characteristics and applications, the applied test protocols as well as the tools used to assess the state and the recovery of patients and types of cycling devices are presented. In addition, the potential benefits of the use of other therapies, like feedback, together with cycling are explored. The application of cycling leg exercise alone and combined with feedback in stroke rehabilitation approaches has shown promising results. Positive effects on motor abilities were found in subacute and chronic patients. However, larger and normalized studies and assessments are needed because there is a high heterogeneity in the patients' characteristics, protocols and metrics. This wil allow the comparison between different studies related with cycling. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  6. Thermodynamic analysis of an integrated gasification solid oxide fuel cell plant combined with an organic Rankine cycle

    DEFF Research Database (Denmark)

    Pierobon, Leonardo; Rokni, Masoud; Larsen, Ulrik

    2013-01-01

    A 100 kWe hybrid plant consisting of gasification system, solid oxide fuel cells and organic Rankine cycle is presented. The nominal power is selected based on cultivation area requirement. For the considered output a land of around 0.5 km2 needs to be utilized. Woodchips are introduced...... into a fixed bed gasification plant to produce syngas which fuels the combined solid oxide fuel cells e organic Rankine cycle system to produce electricity. More than a hundred fluids are considered as possible alternative for the organic cycle using non-ideal equations of state (or state-of-the-art equations...... achieved by simple and double stage organic Rankine cycle plants and around the same efficiency of a combined gasification, solid oxide fuel cells and micro gas turbine plant. © 2013 Elsevier Ltd. All rights reserved....

  7. Energy analysis of technological systems of integrated coal gasification combined cycle power plants

    Energy Technology Data Exchange (ETDEWEB)

    Zaporowski, B.; Roszkiewicz, J.; Sroka, K.; Szczerbowski, R. [Poznan Univ. of Technology (Poland)

    1996-11-01

    The paper presents the energy analysis of technological systems of combined cycle power plants integrated with coal gasification. The mathematical model of the coal gasification process allows to calculate the composition and physical properties of gas obtained in the process of coal gasification. The paper presents an energy analysis of various technological systems of the gas-steam power plants integrated with coal gasification, based on energy and mass balances of gas generator, gas cooler, combustion chamber of gas turbine, gas turbine, steam generator, and steam turbine. The paper contains the following results of calculations: properties of gas obtained in the process of coal gasification, energy parameters of particular devices of power plants, total electric power, and efficiency of electric energy generation in the gas-steam power plants. The conclusions compare the efficiencies of electric energy generation in various technological systems of combined gas-steam power plants integrated with coal gasification. 5 refs, 3 figs, 9 tabs

  8. Combined cycles, impacts of technological requirements; Ciclos combinados, impactos de requerimientos tecnologicos

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Santalo, Jose Miguel [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

    1999-07-01

    The fundamental growth of the Mexican electrical sector for the next ten years is planned on base of the installation of 20 thousand Mw plants of combined cycle. This article presents an analysis of the impact of these power stations finding out that the power stations of combined cycle are at the moment cheaper - from 600 to 700 dollars by installed kW- than the alternative coal options or fuel oil, that are in the range of 900 to 1200 dollars per kW, in addition to which the time required for their construction is shorter. [Spanish] El crecimiento fundamental del sector electrico mexicano para los proximos diez anos esta planeado con base en la instalacion de 20 mil Mw de plantas de ciclo combinado. Este articulo presenta un analisis del impacto de dichas centrales encontrando que las centrales de ciclo combinado actualmente resultan mas baratas - de 600 a 700 dolares por kW instalado - que las opciones alternativas de carbon o combustoleo que estan en el rango de 900 a 1200 dolares por kW, ademas de que los tiempos requeridos para su construccion son menores.

  9. Advanced power cycles and configurations for solar towers: Modeling and optimization of the decoupled solar combined cycle concept

    Science.gov (United States)

    García-Barberena, Javier; Olcoz, Asier; Sorbet, Fco. Javier

    2017-06-01

    CSP technologies are essential to allow large shares of renewables into the grid due to their unique ability to cope with the large variability of the energy resource by means of technically and economically feasible thermal energy storage (TES) systems. However, there is still the need and sought to achieve technological breakthroughs towards cost reductions and increased efficiencies. For this, research on advanced power cycles, like the Decoupled Solar Combined Cycle (DSCC) is, are regarded as a key objective. The DSCC concept is, basically, a Combined Brayton-Rankine cycle in which the bottoming cycle is decoupled from the operation of the topping cycle by means of an intermediate storage system. According to this concept, one or several solar towers driving a solar air receiver and a Gas Turbine (Brayton cycle) feed through their exhaust gasses a single storage system and bottoming cycle. This general concept benefits from a large flexibility in its design. On the one hand, different possible schemes related to number and configuration of solar towers, storage systems media and configuration, bottoming cycles, etc. are possible. On the other, within a specific scheme a large number of design parameters can be optimized, including the solar field size, the operating temperatures and pressures of the receiver, the power of the Brayton and Rankine cycles, the storage capacity and others. Heretofore, DSCC plants have been analyzed by means of simple steady-state models with pre-stablished operating parameters in the power cycles. In this work, a detailed transient simulation model for DSCC plants has been developed and is used to analyze different DSCC plant schemes. For each of the analyzed plant schemes, a sensitivity analysis and selection of the main design parameters is carried out. Results show that an increase in annual solar to electric efficiency of 30% (from 12.91 to 16.78) can be achieved by using two bottoming Rankine cycles at two different

  10. Effect of combined β-alanine and sodium bicarbonate supplementation on cycling performance.

    Science.gov (United States)

    Bellinger, Phillip M; Howe, Samuel T; Shing, Cecilia M; Fell, James W

    2012-08-01

    The purpose of this study was to investigate the effects of 28 d of β-alanine supplementation on 4-min cycling time trial performance and to determine whether there was an additive effect of combined β-alanine and sodium bicarbonate (NaHCO3) supplementation on high-intensity cycling performance. Fourteen highly trained cyclists (mean ± SD: age = 25.4 ± 7.2 yr, mass = 71.1 ± 7.1 kg, V˙O(2max) = 66.6 ± 5.7 mL·kg·min) supplemented for 28 d with β-alanine (65 mg·kg body mass each day) or placebo. A maximal 4-min bout of cycling was performed before supplementation (baseline) and twice after supplementation: after ingestion of NaHCO3 (300 mg·kg body mass) and ingestion of a placebo using a randomized crossover design with 2 d between trials. Blood pH and HCO3 concentration were determined before loading (postsupplementation trials) and at pretest and posttest. In the acute NaHCO3 loading trials, blood pH and HCO3 were elevated from before loading to pretest, and the magnitude of the change in HCO3 from pretest to posttest was significantly greater compared with the acute placebo loading trial (P < 0.001). Average power output in the 4-min cycling performance trial was increased in placebo + NaHCO3 (+3.1% ± 1.8%) and β-alanine + NaHCO3 (+3.3% ± 3.0%) compared with baseline (P < 0.05). β-alanine + placebo did not significantly improve average power output compared with baseline (+1.6% ± 1.7%, P = 0.20); however, magnitude-based inferences demonstrated that β-alanine + placebo was associated with a 37% likelihood of producing average power improvements. In trained cyclists, β-alanine supplementation did not significantly improve 4-min cycling performance; however, there may be a small meaningful improvement in performance. Acute NaHCO3 supplementation significantly improved 4-min cycling performance. There seemed to be a minimal additive effect of combined β-alanine and NaHCO3 supplementation.

  11. Combined Reverse-Brayton Joule Thompson Hydrogen Liquefaction Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Shimko, Martin A. [Gas Equipment Engineering Corporation, Milford, CT (United States); Dunn, Paul M. [Gas Equipment Engineering Corporation, Milford, CT (United States)

    2011-12-31

    The following is a compilation of Annual Progress Reports submitted to the DOE’s Fuel Cell Technologies Office by Gas Equipment Engineering Corp. for contract DE-FG36-05GO15021. The reports cover the project activities from August 2005 through June 2010. The purpose of this project is to produce a pilot-scale liquefaction plant that demonstrates GEECO’s ability to meet or exceed the efficiency targets set by the DOE. This plant will be used as a model to commercialize this technology for use in the distribution infrastructure of hydrogen fuel. It could also be applied to markets distributing hydrogen for industrial gas applications. Extensive modeling of plant performance will be used in the early part of the project to identify the liquefaction cycle architecture that optimizes the twin goals of increased efficiency and reduced cost. The major challenge of the project is to optimize/balance the performance (efficiency) of the plant against the cost of the plant so that the fully amortized cost of liquefying hydrogen meets the aggressive goals set by DOE. This project will design and build a small-scale pilot plant (several hundred kg/day) that will be both a hardware demonstration and a model for scaling to larger plant sizes (>50,000 kg/day). Though an effort will be made to use commercial or near-commercial components, key components that will need development for either a pilot- or full-scale plant will be identified. Prior to starting pilot plant fabrication, these components will be demonstrated at the appropriate scale to demonstrate sufficient performance for use in the pilot plant and the potential to achieve the performance used in modeling the full-scale plant.

  12. Oxygen blast furnace and combined cycle (OBF-CC) - an efficient iron-making and power generation process

    International Nuclear Information System (INIS)

    Jianwei, Y.; Guolong, S.; Cunjiang, K.; Tianjun, Y.

    2003-01-01

    A new iron and power generating process, oxygen blast furnace and combined cycle (OBF-CC), is presented. In order to support the opinion, the features of the oxygen blast furnace and integrated coal gasification and combined cycle (IGCC) are summarized. The relation between the blasting parameters and the output gas quantity, as well as caloric value is calculated based on mass and energy balance. Analysis and calculation indicate that the OBF-CC will be an efficient iron-making and power generation process with higher energy efficiency and less pollution

  13. Waste-heat boiler application for the Vresova combined cycle plant

    Energy Technology Data Exchange (ETDEWEB)

    Vicek, Z. [Energoprojekt Praha, Prague (Czechoslovakia)

    1995-12-01

    This report describes a project proposal and implementation of two combined-cycle units of the Vresova Fuel Complex (PKV) with 2 x 200 MWe and heat supply. Participation of ENERGOPROJECT Praha a.s., in this project.

  14. Smart Operation of Gas Turbine Combined Cycle Plants : Prediction and Improvement of Thermal Efficiency at Part Load

    NARCIS (Netherlands)

    Boksteen, S.Z.

    2014-01-01

    This thesis investigates various operational aspects of Gas Turbine Combined Cycle Power Plants (GTCC). GTCC power plants are expected to play an increasingly important role in the balancing of supply and demand in the electricity grid. Although originally meant for predominantly base load operation

  15. Exergy analysis, parametric analysis and optimization for a novel combined power and ejector refrigeration cycle

    International Nuclear Information System (INIS)

    Dai Yiping; Wang Jiangfeng; Gao Lin

    2009-01-01

    A new combined power and refrigeration cycle is proposed, which combines the Rankine cycle and the ejector refrigeration cycle. This combined cycle produces both power output and refrigeration output simultaneously. It can be driven by the flue gas of gas turbine or engine, solar energy, geothermal energy and industrial waste heats. An exergy analysis is performed to guide the thermodynamic improvement for this cycle. And a parametric analysis is conducted to evaluate the effects of the key thermodynamic parameters on the performance of the combined cycle. In addition, a parameter optimization is achieved by means of genetic algorithm to reach the maximum exergy efficiency. The results show that the biggest exergy loss due to the irreversibility occurs in heat addition processes, and the ejector causes the next largest exergy loss. It is also shown that the turbine inlet pressure, the turbine back pressure, the condenser temperature and the evaporator temperature have significant effects on the turbine power output, refrigeration output and exergy efficiency of the combined cycle. The optimized exergy efficiency is 27.10% under the given condition.

  16. Performance potential of combined cycles integrated with low-Btu gasifiers for future electric utility applications

    Science.gov (United States)

    Nainiger, J. J.; Burns, R. K.

    1977-01-01

    A comparison and an assessment of 10 advanced utility power systems on a consistent basis and to a common level of detail were analyzed. Substantial emphasis was given to a combined cycle systems integrated with low-Btu gasifiers. Performance and cost results from that study were presented for these combined cycle systems, together with a comparative evaluation. The effect of the gasifier type and performance and the interface between the gasifier and the power system were discussed.

  17. Estimating the power efficiency of the thermal power plant modernization by using combined-cycle technologies

    International Nuclear Information System (INIS)

    Hovhannisyan, L.S.; Harutyunyan, N.R.

    2013-01-01

    The power efficiency of the thermal power plant (TPP) modernization by using combined-cycle technologies is introduced. It is shown that it is possible to achieve the greatest decrease in the specific fuel consumption at modernizing the TPP at the expense of introducing progressive 'know-how' of the electric power generation: for TPP on gas, it is combined-cycle, gas-turbine superstructures of steam-power plants and gas-turbines with heat utilization

  18. Combined gas and steam cycle for a gas-cooled solar tower power plant

    Science.gov (United States)

    Becker, B.; Finckh, H. H.; Meyer-Pittroff, R.

    1981-03-01

    The design and optimization of a combined gas and steam turbine cycle incorporating both solar heating and a waste heat steam generator are investigated. Several variants of the combined cycle are considered and efficiency-enhancing features introduced. It is demonstrated that both straight solar and fossil-fueled constant load requirements are met, for a system with 800 C solar receiver temperature and 20 MWe capacity.

  19. Comparative performance analysis of combined-cycle pulse detonation turbofan engines (PDTEs

    Directory of Open Access Journals (Sweden)

    Sudip Bhattrai

    2013-09-01

    Full Text Available Combined-cycle pulse detonation engines are promising contenders for hypersonic propulsion systems. In the present study, design and propulsive performance analysis of combined-cycle pulse detonation turbofan engines (PDTEs is presented. Analysis is done with respect to Mach number at two consecutive modes of operation: (1 Combined-cycle PDTE using a pulse detonation afterburner mode (PDA-mode and (2 combined-cycle PDTE in pulse detonation ramjet engine mode (PDRE-mode. The performance of combined-cycle PDTEs is compared with baseline afterburning turbofan and ramjet engines. The comparison of afterburning modes is done for Mach numbers from 0 to 3 at 15.24 km altitude conditions, while that of pulse detonation ramjet engine (PDRE is done for Mach 1.5 to Mach 6 at 18.3 km altitude conditions. The analysis shows that the propulsive performance of a turbine engine can be greatly improved by replacing the conventional afterburner with a pulse detonation afterburner (PDA. The PDRE also outperforms its ramjet counterpart at all flight conditions considered herein. The gains obtained are outstanding for both the combined-cycle PDTE modes compared to baseline turbofan and ramjet engines.

  20. Modelling of combined cycle power plants using biomass

    Energy Technology Data Exchange (ETDEWEB)

    Jurado, F.; Cano, A. [University of Jaen (Spain). Dept. of Electrical Engineering; Carpio, J. [Universidad Nacional de Educacion a Distancia, Madrid (Spain). Dept. of Electrical and Computer Engineering

    2003-04-01

    The olive tree in Spain can generate large quantities of by-product biomass suitable for gasification. Gasification technologies under development would enable these fuels to be used in gas turbines. Biomass conversion to a clean essentially ash-free form, usually by gasification and purification, is necessary to obtain high efficiency. This paper reports results of detailed full-load performance modelling of cogeneration systems based on gasifier/gas turbine technologies. (Author)

  1. Thermoeconomic optimization of a combined-cycle solar tower power plant

    International Nuclear Information System (INIS)

    Spelling, James; Favrat, Daniel; Martin, Andrew; Augsburger, Germain

    2012-01-01

    A dynamic model of a pure-solar combined-cycle power plant has been developed in order to allow determination of the thermodynamic and economic performance of the plant for a variety of operating conditions and superstructure layouts. The model was then used for multi-objective thermoeconomic optimization of both the power plant performance and cost, using a population-based evolutionary algorithm. In order to examine the trade-offs that must be made, two conflicting objectives will be considered, namely minimal investment costs and minimal levelized electricity costs. It was shown that efficiencies in the region of 18–24% can be achieved, and this for levelized electricity costs in the region of 12–24 UScts/kWh e , depending on the magnitude of the initial investment, making the system competitive with current solar thermal technology. -- Highlights: ► Pure-solar combined-cycle studied using thermoeconomic tools. ► Multi-objective optimization conducted to determine Pareto-optimal power plant designs. ► Levelised costs between 12 and 24 UScts/kWhe predicted. ► Efficiencies between 18 and 24% predicted.

  2. A unified model of combined energy systems with different cycle modes and its optimum performance characteristics

    International Nuclear Information System (INIS)

    Zhang Yue; Hu, Weiqiang; Ou Congjie; Chen Jincan

    2009-01-01

    A unified model is presented for a class of combined energy systems, in which the systems mainly consist of a heat engine, a combustor and a counter-flow heat exchanger and the heat engine in the systems may have different thermodynamic cycle modes such as the Brayton cycle, Carnot cycle, Stirling cycle, Ericsson cycle, and so on. Not only the irreversibilities of the heat leak and finite-rate heat transfer but also the different cycle modes of the heat engine are considered in the model. On the basis of Newton's law, expressions for the overall efficiency and power output of the combined energy system with an irreversible Brayton cycle are derived. The maximum overall efficiency and power output and other relevant parameters are calculated. The general characteristic curves of the system are presented for some given parameters. Several interesting cases are discussed in detail. The results obtained here are very general and significant and can be used to discuss the optimal performance characteristics of a class of combined energy systems with different cycle modes. Moreover, it is significant to point out that not only the important conclusions obtained in Bejan's first combustor model and Peterson's general combustion driven model but also the optimal performance of a class of solar-driven heat engine systems can be directly derived from the present paper under some limit conditions

  3. A unified model of combined energy systems with different cycle modes and its optimum performance characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yue [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); College of Information Science and Engineering, Huaqiao University, Quanzhou 362021 (China); Hu, Weiqiang [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China); Ou Congjie [College of Information Science and Engineering, Huaqiao University, Quanzhou 362021 (China); Chen Jincan [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China)], E-mail: jcchen@xmu.edu.cn

    2009-06-15

    A unified model is presented for a class of combined energy systems, in which the systems mainly consist of a heat engine, a combustor and a counter-flow heat exchanger and the heat engine in the systems may have different thermodynamic cycle modes such as the Brayton cycle, Carnot cycle, Stirling cycle, Ericsson cycle, and so on. Not only the irreversibilities of the heat leak and finite-rate heat transfer but also the different cycle modes of the heat engine are considered in the model. On the basis of Newton's law, expressions for the overall efficiency and power output of the combined energy system with an irreversible Brayton cycle are derived. The maximum overall efficiency and power output and other relevant parameters are calculated. The general characteristic curves of the system are presented for some given parameters. Several interesting cases are discussed in detail. The results obtained here are very general and significant and can be used to discuss the optimal performance characteristics of a class of combined energy systems with different cycle modes. Moreover, it is significant to point out that not only the important conclusions obtained in Bejan's first combustor model and Peterson's general combustion driven model but also the optimal performance of a class of solar-driven heat engine systems can be directly derived from the present paper under some limit conditions.

  4. Estimate for interstage water injection in air compressor incorporated into gas-turbine cycles and combined power plants cycles

    Science.gov (United States)

    Kler, A. M.; Zakharov, Yu. B.; Potanina, Yu. M.

    2017-05-01

    The objects of study are the gas turbine (GT) plant and combined cycle power plant (CCPP) with opportunity for injection between the stages of air compressor. The objective of this paper is technical and economy optimization calculations for these classes of plants with water interstage injection. The integrated development environment "System of machine building program" was a tool for creating the mathematic models for these classes of power plants. Optimization calculations with the criterion of minimum for specific capital investment as a function of the unit efficiency have been carried out. For a gas-turbine plant, the economic gain from water injection exists for entire range of power efficiency. For the combined cycle plant, the economic benefit was observed only for a certain range of plant's power efficiency.

  5. Exergetic Analysis of a Novel Solar Cooling System for Combined Cycle Power Plants

    Directory of Open Access Journals (Sweden)

    Francesco Calise

    2016-09-01

    Full Text Available This paper presents a detailed exergetic analysis of a novel high-temperature Solar Assisted Combined Cycle (SACC power plant. The system includes a solar field consisting of innovative high-temperature flat plate evacuated solar thermal collectors, a double stage LiBr-H2O absorption chiller, pumps, heat exchangers, storage tanks, mixers, diverters, controllers and a simple single-pressure Combined Cycle (CC power plant. Here, a high temperature solar cooling system is coupled with a conventional combined cycle, in order to pre-cool gas turbine inlet air in order to enhance system efficiency and electrical capacity. In this paper, the system is analyzed from an exergetic point of view, on the basis of an energy-economic model presented in a recent work, where the obtained main results show that SACC exhibits a higher electrical production and efficiency with respect to the conventional CC. The system performance is evaluated by a dynamic simulation, where detailed simulation models are implemented for all the components included in the system. In addition, for all the components and for the system as whole, energy and exergy balances are implemented in order to calculate the magnitude of the irreversibilities within the system. In fact, exergy analysis is used in order to assess: exergy destructions and exergetic efficiencies. Such parameters are used in order to evaluate the magnitude of the irreversibilities in the system and to identify the sources of such irreversibilities. Exergetic efficiencies and exergy destructions are dynamically calculated for the 1-year operation of the system. Similarly, exergetic results are also integrated on weekly and yearly bases in order to evaluate the corresponding irreversibilities. The results showed that the components of the Joule cycle (combustor, turbine and compressor are the major sources of irreversibilities. System overall exergetic efficiency was around 48%. Average weekly solar collector

  6. NOVEL GAS CLEANING/CONDITIONING FOR INTEGRATED GASIFICATION COMBINED CYCLE

    Energy Technology Data Exchange (ETDEWEB)

    Dennis A. Horazak; Richard A. Newby; Eugene E. Smeltzer; Rachid B. Slimane; P. Vann Bush; James L. Aderhold Jr; Bruce G. Bryan

    2005-12-01

    lower for the Filter-Reactor Novel Gas Cleaning processes than for the conventional processes, the improved power plant capacity results in the potential for significant reductions in the plant cost-of-electricity, about 4.5% for the Current Standards case, and more than 7% for the Future Standards case. For Methanol Synthesis, the Novel Gas Cleaning process scheme again shows the potential for significant advantages over the conventional gas cleaning schemes. The plant generating capacity is increased more than 7% and there is a 2.3%-point gain in plant thermal efficiency. The Total Capital Requirement is reduced by about 13% and the cost-of-electricity is reduced by almost 9%. For both IGCC Methanol Synthesis cases, there are opportunities to combine some of the filter-reactor polishing stages to simplify the process further to reduce its cost. This evaluation has devised plausible humid-gas cleaning schemes for the Filter-Reactor Novel Gas Cleaning process that might be applied in IGCC and Methanol Synthesis applications.

  7. Multi-objective thermodynamic optimization of combined Brayton and inverse Brayton cycles using genetic algorithms

    International Nuclear Information System (INIS)

    Besarati, S.M.; Atashkari, K.; Jamali, A.; Hajiloo, A.; Nariman-zadeh, N.

    2010-01-01

    This paper presents a simultaneous optimization study of two outputs performance of a previously proposed combined Brayton and inverse Brayton cycles. It has been carried out by varying the upper cycle pressure ratio, the expansion pressure of the bottom cycle and using variable, above atmospheric, bottom cycle inlet pressure. Multi-objective genetic algorithms are used for Pareto approach optimization of the cycle outputs. The two important conflicting thermodynamic objectives that have been considered in this work are net specific work (w s ) and thermal efficiency (η th ). It is shown that some interesting features among optimal objective functions and decision variables involved in the Baryton and inverse Brayton cycles can be discovered consequently.

  8. The combined effects of menstrual cycle phase and acute stress on reward-related processing

    NARCIS (Netherlands)

    Banis, Stella; Lorist, Monicque M.

    We investigated the combined effects of menstrual cycle phase and acute stress on reward-related processing, employing a monetary incentive delay task in combination with EEG. Females participated during late follicular and late luteal phases, performing in both control and stress conditions. We

  9. Evaluation of ejector performance for an organic Rankine cycle combined power and cooling system

    International Nuclear Information System (INIS)

    Zhang, Kun; Chen, Xue; Markides, Christos N.; Yang, Yong; Shen, Shengqiang

    2016-01-01

    Highlights: • The performance of an ejector in an Organic Rankine Cycle and ejector refrigeration cycle (EORC) was evaluated. • The achieved entrainment ratio and COP of an EORC system is affected significantly by the evaporator conditions (such as temperature, pressure and flow rate). • An optimum distance of 6 mm nozzle position was found that ensures a maximum entrainment ratio, the best efficiency and lowest loss in the ejector. • A reduced total pressure loss between the nozzle inlet and exit leads to a lower energy loss, a higher entrainment ratio and better overall ejector performance. - Abstract: Power-generation systems based on organic Rankine cycles (ORCs) are well suited and increasingly employed in the conversion of thermal energy from low temperature heat sources to power. These systems can be driven by waste heat, for example from various industrial processes, as well as solar or geothermal energy. A useful extension of such systems involves a combined ORC and ejector-refrigeration cycle (EORC) that is capable, at low cost and complexity, of producing useful power while having a simultaneous capacity for cooling that is highly desirable in many applications. A significant thermodynamic loss in such a combined energy system takes place in the ejector due to unavoidable losses caused by irreversible mixing in this component. This paper focuses on the flow and transport processes in an ejector, in order to understand and quantify the underlying reasons for these losses, as well as their sensitivity to important design parameters and operational variables. Specifically, the study considers, beyond variations to the geometric design of the ejector, also the role of changing the external conditions across this component and how these affect its performance; this is not only important in helping develop ejector designs in the first instance, but also in evaluating how the performance may shift (in fact, deteriorate) quantitatively when the device

  10. The use of gas based energy conversion cycles for sodium fast reactors

    International Nuclear Information System (INIS)

    Saez, M.; Haubensack, D.; Alpy, N.; Gerber, A.; Daid, F.

    2008-01-01

    In the frame of Sodium Fast Reactors, CEA, AREVA and EDF are involved in a substantial effort providing both significant expertise and original work in order to investigate the interest to use a gas based energy conversion cycle as an alternative to the classical steam cycle. These gas cycles consist in different versions of the Brayton cycle, various types of gas being considered (helium, nitrogen, argon, separately or mixed, sub or supercritical carbon dioxide) as well as various cycle arrangements (indirect, indirect / combined cycles). The interest of such cycles is analysed in details by thermodynamic calculations and cycle optimisations. The objective of this paper is to provide a comparison between gas based energy conversion cycles from the viewpoint of the overall plant efficiency. Key factors affecting the Brayton cycle efficiency include the turbine inlet temperature, compressors and turbine efficiencies, recuperator effectiveness and cycle pressure losses. A nitrogen Brayton cycle at high pressure (between 100 and 180 bar) could appear as a potential near-term solution of classical gas power conversion system for maximizing the plant efficiency. At long-term, supercritical carbon dioxide Brayton cycle appears very promising for Sodium Fast Reactors, with a potential of high efficiency using even at a core outlet temperature of 545 deg. C. (authors)

  11. Model predictive control system and method for integrated gasification combined cycle power generation

    Science.gov (United States)

    Kumar, Aditya; Shi, Ruijie; Kumar, Rajeeva; Dokucu, Mustafa

    2013-04-09

    Control system and method for controlling an integrated gasification combined cycle (IGCC) plant are provided. The system may include a controller coupled to a dynamic model of the plant to process a prediction of plant performance and determine a control strategy for the IGCC plant over a time horizon subject to plant constraints. The control strategy may include control functionality to meet a tracking objective and control functionality to meet an optimization objective. The control strategy may be configured to prioritize the tracking objective over the optimization objective based on a coordinate transformation, such as an orthogonal or quasi-orthogonal projection. A plurality of plant control knobs may be set in accordance with the control strategy to generate a sequence of coordinated multivariable control inputs to meet the tracking objective and the optimization objective subject to the prioritization resulting from the coordinate transformation.

  12. Graded Cycling Test Combined With the Talk Test Is Responsive in Cardiac Rehabilitation

    DEFF Research Database (Denmark)

    Nielsen, Susanne Grøn; Vinther, Anders

    2016-01-01

    changes in watts (W) were compared with the standard error of measurement (SEM95) for groups and the smallest real difference (SRD) for individuals. Minimal clinically important difference was assessed by comparing patient perceived changes in physical fitness with the test changes. RESULTS......PURPOSE: To evaluate clinical assessment outcome of cardiac rehabilitation, a simple and reliable submaximal exercise test, not based on heart rate, is warranted. The Talk Test (TT) has been found to correlate well with the ventilatory threshold, and excellent reliability was observed for TT...... combined with the Graded Cycling Test (GCT-TT) in cardiac patients. The purpose was to investigate responsiveness of GCT-TT in cardiac rehabilitation patients. METHODS: Patients (n = 93) referred to 8 weeks of cardiac rehabilitation were included. Pre- and posttests were performed using GCT-TT. Mean test...

  13. Thermodynamic and design considerations of organic Rankine cycles in combined application with a solar thermal gas turbine

    Science.gov (United States)

    Braun, R.; Kusterer, K.; Sugimoto, T.; Tanimura, K.; Bohn, D.

    2013-12-01

    Concentrated Solar Power (CSP) technologies are considered to provide a significant contribution for the electric power production in the future. Different kinds of technologies are presently in operation or under development, e.g. parabolic troughs, central receivers, solar dish systems and Fresnel reflectors. This paper takes the focus on central receiver technologies, where the solar radiation is concentrated by a field of heliostats in a receiver on the top of a tall tower. To get this CSP technology ready for the future, the system costs have to reduce significantly. The main cost driver in such kind of CSP technologies are the huge amount of heliostats. To reduce the amount of heliostats, and so the investment costs, the efficiency of the energy conversion cycle becomes an important issue. An increase in the cycle efficiency results in a decrease of the solar heliostat field and thus, in a significant cost reduction. The paper presents the results of a thermodynamic model of an Organic Rankine Cycle (ORC) for combined cycle application together with a solar thermal gas turbine. The gas turbine cycle is modeled with an additional intercooler and recuperator and is based on a typical industrial gas turbine in the 2 MW class. The gas turbine has a two stage radial compressor and a three stage axial turbine. The compressed air is preheated within a solar receiver to 950°C before entering the combustor. A hybrid operation of the gas turbine is considered. In order to achieve a further increase of the overall efficiency, the combined operation of the gas turbine and an Organic Rankine Cycle is considered. Therefore an ORC has been set up, which is thermally connected to the gas turbine cycle at two positions. The ORC can be coupled to the solar-thermal gas turbine cycle at the intercooler and after the recuperator. Thus, waste heat from different cycle positions can be transferred to the ORC for additional production of electricity. Within this investigation

  14. A novel nuclear combined power and cooling system integrating high temperature gas-cooled reactor with ammonia–water cycle

    International Nuclear Information System (INIS)

    Luo, Chending; Zhao, Fuqiang; Zhang, Na

    2014-01-01

    Highlights: • We propose a novel nuclear ammonia–water power and cooling cogeneration system. • The high temperature reactor is inherently safe, with exhaust heat fully recovered. • The thermal performances are improved compared with nuclear combined cycle. • The base case attains an energy efficiency of 69.9% and exergy efficiency of 72.5%. • Energy conservation and emission reduction are achieved in this cogeneration way. - Abstract: A nuclear ammonia–water power and refrigeration cogeneration system (NAPR) has been proposed and analyzed in this paper. It consists of a closed high temperature gas-cooled reactor (HTGR) topping Brayton cycle and a modified ammonia water power/refrigeration combined bottoming cycle (APR). The HTGR is an inherently safe reactor, and thus could be stable, flexible and suitable for various energy supply situation, and its exhaust heat is fully recovered by the mixture of ammonia and water in the bottoming cycle. To reduce exergy losses and enhance outputs, the ammonia concentrations of the bottoming cycle working fluid are optimized in both power and refrigeration processes. With the HTGR of 200 MW thermal capacity and 900 °C/70 bar reactor-core-outlet helium, the system achieves 88.8 MW net electrical output and 9.27 MW refrigeration capacity, and also attains an energy efficiency of 69.9% and exergy efficiency of 72.5%, which are higher by 5.3%-points and 2.6%-points as compared with the nuclear combined cycle (NCC, like a conventional gas/steam power-only combined cycle while the topping cycle is a closed HTGR Brayton cycle) with the same nuclear energy input. Compared with conventional separate power and refrigeration generation systems, the fossil fuel saving (based on CH 4 ) and CO 2 emission reduction of base-case NAPR could reach ∼9.66 × 10 4 t/y and ∼26.6 × 10 4 t/y, respectively. The system integration accomplishes the safe and high-efficiency utilization of nuclear energy by power and refrigeration

  15. Promising Direction of Perfection of the Utilization Combine Cycle Gas Turbine Units

    Directory of Open Access Journals (Sweden)

    Gabdullina Albina I.

    2017-01-01

    Full Text Available Issues of improving the efficiency of combined cycle gas turbines (CCGT recovery type have been presented. Efficiency gas turbine plant reaches values of 45 % due to rise in temperature to a gas turbine to 1700 °C. Modern technologies for improving the cooling gas turbine components and reducing the excess air ratio leads to a further increase of the efficiency by 1-2 %. Based on research conducted at the Tomsk Polytechnic University, it shows that the CCGT efficiency can be increased by 2-3 % in the winter time due to the use of organic Rankine cycle, low-boiling substances, and air-cooled condensers (ACC. It is necessary to apply the waste heat recovery with condensation of water vapor from the flue gas, it will enhance the efficiency of the CCGT by 2-3 % to increase the efficiency of the heat recovery steam boiler (HRSB to 10-12 %. Replacing electric pumps gas turbine engine (GTE helps to reduce electricity consumption for auxiliary needs CCGT by 0.5-1.5 %. At the same time the heat of flue gas turbine engine may be useful used in HRSB, thus will increase the capacity and efficiency of the steam turbine.

  16. Apparatus and methods for supplying auxiliary steam in a combined cycle system

    Science.gov (United States)

    Gorman, William G.; Carberg, William George; Jones, Charles Michael

    2002-01-01

    To provide auxiliary steam, a low pressure valve is opened in a combined cycle system to divert low pressure steam from the heat recovery steam generator to a header for supplying steam to a second combined cycle's steam turbine seals, sparging devices and cooling steam for the steam turbine if the steam turbine and gas turbine lie on a common shaft with the generator. Cooling steam is supplied the gas turbine in the combined cycle system from the high pressure steam turbine. Spent gas turbine cooling steam may augment the low pressure steam supplied to the header by opening a high pressure valve whereby high and low pressure steam flows are combined. An attemperator is used to reduce the temperature of the combined steam in response to auxiliary steam flows above a predetermined flow and a steam header temperature above a predetermined temperature. The auxiliary steam may be used to start additional combined cycle units or to provide a host unit with steam turbine cooling and sealing steam during full-speed no-load operation after a load rejection.

  17. Minimization of the LCA impact of thermodynamic cycles using a combined simulation-optimization approach

    International Nuclear Information System (INIS)

    Brunet, Robert; Cortés, Daniel; Guillén-Gosálbez, Gonzalo; Jiménez, Laureano; Boer, Dieter

    2012-01-01

    This work presents a computational approach for the simultaneous minimization of the total cost and environmental impact of thermodynamic cycles. Our method combines process simulation, multi-objective optimization and life cycle assessment (LCA) within a unified framework that identifies in a systematic manner optimal design and operating conditions according to several economic and LCA impacts. Our approach takes advantages of the complementary strengths of process simulation (in which mass, energy balances and thermodynamic calculations are implemented in an easy manner) and rigorous deterministic optimization tools. We demonstrate the capabilities of this strategy by means of two case studies in which we address the design of a 10 MW Rankine cycle modeled in Aspen Hysys, and a 90 kW ammonia-water absorption cooling cycle implemented in Aspen Plus. Numerical results show that it is possible to achieve environmental and cost savings using our rigorous approach. - Highlights: ► Novel framework for the optimal design of thermdoynamic cycles. ► Combined use of simulation and optimization tools. ► Optimal design and operating conditions according to several economic and LCA impacts. ► Design of a 10MW Rankine cycle in Aspen Hysys, and a 90kW absorption cycle in Aspen Plus.

  18. Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part B: Application on a Case Study

    Directory of Open Access Journals (Sweden)

    Angelo La Seta

    2016-05-01

    Full Text Available Organic Rankine cycle (ORC power systems have recently emerged as promising solutions for waste heat recovery in low- and medium-size power plants. Their performance and economic feasibility strongly depend on the expander. The design process and efficiency estimation are particularly challenging due to the peculiar physical properties of the working fluid and the gas-dynamic phenomena occurring in the machine. Unlike steam Rankine and Brayton engines, organic Rankine cycle expanders combine small enthalpy drops with large expansion ratios. These features yield turbine designs with few highly-loaded stages in supersonic flow regimes. Part A of this two-part paper has presented the implementation and validation of the simulation tool TURAX, which provides the optimal preliminary design of single-stage axial-flow turbines. The authors have also presented a sensitivity analysis on the decision variables affecting the turbine design. Part B of this two-part paper presents the first application of a design method where the thermodynamic cycle optimization is combined with calculations of the maximum expander performance using the mean-line design tool described in part A. The high computational cost of the turbine optimization is tackled by building a model which gives the optimal preliminary design of an axial-flow turbine as a function of the cycle conditions. This allows for estimating the optimal expander performance for each operating condition of interest. The test case is the preliminary design of an organic Rankine cycle turbogenerator to increase the overall energy efficiency of an offshore platform. For an increase in expander pressure ratio from 10 to 35, the results indicate up to 10% point reduction in expander performance. This corresponds to a relative reduction in net power output of 8.3% compared to the case when the turbine efficiency is assumed to be 80%. This work also demonstrates that this approach can support the plant designer

  19. A combined power cycle utilizing low-temperature waste heat and LNG cold energy

    International Nuclear Information System (INIS)

    Shi Xiaojun; Che Defu

    2009-01-01

    This paper has proposed a combined power system, in which low-temperature waste heat can be efficiently recovered and cold energy of liquefied natural gas (LNG) can be fully utilized as well. This system consists of an ammonia-water mixture Rankine cycle and an LNG power generation cycle, and it is modelled by considering mass, energy and species balances for every component and thermodynamic analyses are conducted. The results show that the proposed combined cycle has good performance, with net electrical efficiency and exergy efficiency of 33% and 48%, respectively, for a typical operating condition. The power output is equal to 1.25 MWh per kg of ammonia-water mixture. About 0.2 MW of electrical power for operating sea water pumps can be saved. Parametric analyses are performed for the proposed combined cycle to evaluate the effects of key factors on the performance of the proposed combined cycle through simulation calculations. Results show that a maximum net electrical efficiency can be obtained as the inlet pressure of ammonia turbine increases and the peak value increases as the ammonia mass fraction increases. Exergy efficiency goes up with the increased ammonia turbine inlet pressure. With the ammonia mass fraction increases, the net electrical efficiency increases, whereas exergy efficiency decreases. For increasing LNG turbine inlet pressure or heat source temperature, there is also a peak of net electrical efficiency and exergy efficiency. With the increase of LNG gas turbine outlet pressure, exergy efficiency increases while net electrical efficiency drops

  20. Power and efficiency optimization for combined Brayton and inverse Brayton cycles

    International Nuclear Information System (INIS)

    Zhang Wanli; Chen Lingen; Sun Fengrui

    2009-01-01

    A thermodynamic model for open combined Brayton and inverse Brayton cycles is established considering the pressure drops of the working fluid along the flow processes and the size constraints of the real power plant using finite time thermodynamics in this paper. There are 11 flow resistances encountered by the gas stream for the combined Brayton and inverse Brayton cycles. Four of these, the friction through the blades and vanes of the compressors and the turbines, are related to the isentropic efficiencies. The remaining flow resistances are always present because of the changes in flow cross-section at the compressor inlet of the top cycle, combustion inlet and outlet, turbine outlet of the top cycle, turbine outlet of the bottom cycle, heat exchanger inlet, and compressor inlet of the bottom cycle. These resistances control the air flow rate and the net power output. The relative pressure drops associated with the flow through various cross-sectional areas are derived as functions of the compressor inlet relative pressure drop of the top cycle. The analytical formulae about the relations between power output, thermal conversion efficiency, and the compressor pressure ratio of the top cycle are derived with the 11 pressure drop losses in the intake, compression, combustion, expansion, and flow process in the piping, the heat transfer loss to the ambient, the irreversible compression and expansion losses in the compressors and the turbines, and the irreversible combustion loss in the combustion chamber. The performance of the model cycle is optimized by adjusting the compressor inlet pressure of the bottom cycle, the air mass flow rate and the distribution of pressure losses along the flow path. It is shown that the power output has a maximum with respect to the compressor inlet pressure of the bottom cycle, the air mass flow rate or any of the overall pressure drops, and the maximized power output has an additional maximum with respect to the compressor pressure

  1. Thermal energy storage for an integrated coal gasification combined-cycle power plant

    Energy Technology Data Exchange (ETDEWEB)

    Drost, K.; Antoniak, Z.; Brown, D.; Somasundaram, S.

    1991-10-01

    This study investigates the use of molten nitrate salt thermal energy storage in an integrated gasification combined-cycle power plant allowing the facility to economically provide peak- and intermediate-load electric power. The results of the study show that an integrated gasification combined-cycle power plant with thermal energy storage can reduce the cost of coal-fired peak- or intermediate-load electric power by between 5% and 20% depending on the plants operating schedule. The use of direct-contact salt heating can further improve the economic attractiveness of the concept. 12 refs., 1 fig., 5 tabs.

  2. Performance analysis and binary working fluid selection of combined flash-binary geothermal cycle

    International Nuclear Information System (INIS)

    Zeyghami, Mehdi

    2015-01-01

    Performance of the combined flash-binary geothermal power cycle for geofluid temperatures between 150 and 250 °C is studied. A thermodynamic model is developed, and the suitable binary working fluids for different geofluid temperatures are identified from a list of thirty working fluid candidates, consisting environmental friendly refrigerants and hydrocarbons. The overall system exergy destruction and Vapor Expansion Ratio across the binary cycle turbine are selected as key performance indicators. The results show that for low-temperature heat sources using refrigerants as binary working fluids result in higher overall cycle efficiency and for medium and high-temperature resources, hydrocarbons are more suitable. For combined flash-binary cycle, secondary working fluids; R-152a, Butane and Cis-butane show the best performances at geofluid temperatures 150, 200 and 250 °C respectively. The overall second law efficiency is calculated as high as 0.48, 0.55 and 0.58 for geofluid temperatures equal 150, 200 and 250 °C respectively. The flash separator pressure found to has important effects on cycle operation and performance. Separator pressure dictates the work production share of steam and binary parts of the system. And there is an optimal separator pressure at which overall exergy destruction of the cycle achieves its minimum value. - Highlights: • Performance of the combined flash-binary geothermal cycle is investigated. • Thirty different fluids are screened to find the most suitable ORC working fluid. • Optimum cycle operation conditions presented for geofluids between 150 °C and 250 °C. • Refrigerants are more suitable for the ORC at geothermal sources temperature ≤200 °C. • Hydrocarbons are more suitable for the ORC at geothermal sources temperature >200 °C

  3. Cycle water chemistry based on film forming amines at power plants: evaluation of technical guidance documents

    Science.gov (United States)

    Dyachenko, F. V.; Petrova, T. I.

    2017-11-01

    Efficiency and reliability of the equipment in fossil power plants as well as in combined cycle power plants depend on the corrosion processes and deposit formation in steam/water circuit. In order to decrease these processes different water chemistries are used. Today the great attention is being attracted to the application of film forming amines and film forming amine products. The International Association for the Properties of Water and Steam (IAPWS) consolidated the information from all over the World, and based on the research studies and operating experience of researchers and engineers from 21 countries, developed and authorized the Technical Guidance Document: “Application of Film Forming Amines in Fossil, Combined Cycle, and Biomass Power Plants” in 2016. This article describe Russian and International technical guidance documents for the cycle water chemistries based on film forming amines at fossil and combined cycle power plants.

  4. Concept for fuel-cycle based safeguards

    International Nuclear Information System (INIS)

    deMontmollin, J.M.; Higinbotham, W.A.; Gupta, D.

    1985-01-01

    Although the guidelines for NPT safeguards specify that the State's fuel cycle and degree of international independence are to be taken into account, the same model approach and absolute-quantity inspection goals are applied to all similar facilities, irrespective of the State's fuel cycle, and the findings are reported in those terms. A concept whereby safeguards might more effectively and efficiently accomplish the purposes of NPT safeguards is explored. The principal features are: (1) division of the fuel cycle into three zones, each containing material having a different degree of significance for safeguards; (2) closing a verified material balance around each zone, supplementing the present MBA balances for more sensitive facilities and replacing them for others; (3) maintenance by the IAEA of a current book inventory for each facility by means of immediate, abbreviated reporting of interfacility transfers; (4) near real-time analysis of material flow patterns through the fuel cycle; and (5) a periodic statement of the findings for the entire State that takes the form that there is assurance that all nuclear materials under safeguards are accounted for to some stated degree of uncertainty

  5. Nuclear Air-Brayton Combined Cycle Power Conversion Design, Physical Performance Estimation and Economic Assessment

    Science.gov (United States)

    Andreades, Charalampos

    The combination of an increased demand for electricity for economic development in parallel with the widespread push for adoption of renewable energy sources and the trend toward liberalized markets has placed a tremendous amount of stress on generators, system operators, and consumers. Non-guaranteed cost recovery, intermittent capacity, and highly volatile market prices are all part of new electricity grids. In order to try and remediate some of these effects, this dissertation proposes and studies the design and performance, both physical and economic, of a novel power conversion system, the Nuclear Air-Brayton Combined Cycle (NACC). The NACC is a power conversion system that takes a conventional industrial frame type gas turbine, modifies it to accept external nuclear heat at 670°C, while also maintaining its ability to co-fire with natural gas to increase temperature and power output at a very quick ramp rate. The NACC addresses the above issues by allowing the generator to gain extra revenue through the provision of ancillary services in addition to energy payments, the grid operator to have a highly flexible source of capacity to back up intermittent renewable energy sources, and the consumer to possibly see less volatile electricity prices and a reduced probability of black/brown outs. This dissertation is split into six sections that delve into specific design and economic issues related to the NACC. The first section describes the basic design and modifications necessary to create a functional externally heated gas turbine, sets a baseline design based upon the GE 7FB, and estimates its physical performance under nominal conditions. The second section explores the off-nominal performance of the NACC and characterizes its startup and shutdown sequences, along with some of its safety measures. The third section deals with the power ramp rate estimation of the NACC, a key performance parameter in a renewable-heavy grid that needs flexible capacity. The

  6. Total environmental impacts of biofuels from corn stover using a hybrid life cycle assessment model combining process life cycle assessment and economic input-output life cycle assessment.

    Science.gov (United States)

    Liu, Changqi; Huang, Yaji; Wang, Xinye; Tai, Yang; Liu, Lingqin; Liu, Hao

    2018-01-01

    Studies on the environmental analysis of biofuels by fast pyrolysis and hydroprocessing (BFPH) have so far focused only on the environmental impacts from direct emissions and have included few indirect emissions. The influence of ignoring some indirect emissions on the environmental performance of BFPH has not been well investigated and hence is not really understood. In addition, in order to avoid shifting environmental problems from one medium to another, a comprehensive assessment of environmental impacts caused by the processes must quantify the environmental emissions to all media (air, water, and land) in relation to each life cycle stage. A well-to-wheels assessment of the total environmental impacts resulting from direct emissions and indirect emissions of a BFPH system with corn stover is conducted using a hybrid life cycle assessment (LCA) model combining the economic input-output LCA and the process LCA. The Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI) has been used to estimate the environmental impacts in terms of acidification, eutrophication, global climate change, ozone depletion, human health criteria, photochemical smog formation, ecotoxicity, human health cancer, and human health noncancer caused by 1 MJ biofuel production. Taking account of all the indirect greenhouse gas (GHG) emissions, the net GHG emissions (81.8 g CO 2 eq/MJ) of the biofuels are still less than those of petroleum-based fuels (94 g CO 2 eq/MJ). Maize production and pyrolysis and hydroprocessing make major contributions to all impact categories except the human health criteria. All impact categories resulting from indirect emissions except eutrophication and smog air make more than 24% contribution to the total environmental impacts. Therefore, the indirect emissions are important and cannot be ignored. Sensitivity analysis has shown that corn stover yield and bio-oil yield affect the total environmental impacts of the biofuels

  7. Optimization of preventive maintenance cycle based on experimental feedback in nuclear power plants

    International Nuclear Information System (INIS)

    Shi Jie

    2010-01-01

    The preventive replacement method based on the experimental feedback was introduced. In this method, the initial preventive replacement cycle was acquired by expert votes. The preventive replacement cycle combined with the operation experience of the equipment was gained by means of Bayesian theorem. The Optimized preventive replacement cycle can be acquired by comparing the two probabilities that no fault occurs within the cycle. This method was tested on the switches which were used in Daya Bay Nuclear Power Plant and the results indicated its validity. (authors)

  8. Conversion of a hard coal fired power plant into a modern combined cycle

    Energy Technology Data Exchange (ETDEWEB)

    Brandauer, M. [Badenwerk AG, Karlsruhe (Germany)

    1997-12-31

    The repowering of a coal fired power plant into a modern combined cycle is described. The plant is located in Karlsruhe, Germany. The hard coal fired boiler is replaced by a gas turbine with a heat recovery steam generator. The initial steam turbine as well as major components of the water-steam cycle were revised and integrated in the new plant. To guarantee fast start-up times, an unfired once through type steam generator was chosen. The heat recovery steam generator is connected to a gas turbine, firing natural gas or fuel oil no. 2. In repowering the plant, thermal efficiency increased from 38% for the steam power plant to about 58% in combined cycle application. 6 refs., 5 figs., 3 tabs.

  9. Evaluation of Indirect Combined Cycle in Very High Temperature Gas--Cooled Reactor

    International Nuclear Information System (INIS)

    Chang Oh; Robert Barner; Cliff Davis; Steven Sherman; Paul Pickard

    2006-01-01

    The U.S. Department of Energy and Idaho National Laboratory are developing a very high temperature reactor to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is twofold: (a) efficient, low-cost energy generation and (b) hydrogen production. Although a next-generation plant could be developed as a single-purpose facility, early designs are expected to be dual purpose, as assumed here. A dual-purpose design with a combined cycle of a Brayton top cycle and a bottom Rankine cycle was investigated. An intermediate heat transport loop for transporting heat to a hydrogen production plant was used. Helium, CO2, and a helium-nitrogen mixture were studied to determine the best working fluid in terms of the cycle efficiency. The relative component sizes were estimated for the different working fluids to provide an indication of the relative capital costs. The relative size of the turbomachinery was measured by comparing the power input/output of the component. For heat exchangers the volume was computed and compared. Parametric studies away from the baseline values of the cycle were performed to determine the effects of varying conditions in the cycle. This gives some insight into the sensitivity of the cycle to various operating conditions as well as trade-offs between efficiency and component size. Parametric studies were carried out on reactor outlet temperature, mass flow, pressure, and turbine cooling

  10. Combined cycle solar central receiver hybrid power system study. Volume III. Appendices. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-11-01

    A design study for a 100 MW gas turbine/steam turbine combined cycle solar/fossil-fuel hybrid power plant is presented. This volume contains the appendices: (a) preconceptual design data; (b) market potential analysis methodology; (c) parametric analysis methodology; (d) EPGS systems description; (e) commercial-scale solar hybrid power system assessment; and (f) conceptual design data lists. (WHK)

  11. The optimization air separation plants for combined cycle MHD-power plant applications

    Science.gov (United States)

    Juhasz, A. J.; Springmann, H.; Greenberg, R.

    1980-01-01

    Some of the design approaches being employed during a current supported study directed at developing an improved air separation process for the production of oxygen enriched air for magnetohydrodynamics (MHD) combustion are outlined. The ultimate objective is to arrive at conceptual designs of air separation plants, optimized for minimum specific power consumption and capital investment costs, for integration with MHD combined cycle power plants.

  12. COMBINED CYCLE GAS TURBINE FOR THERMAL POWER STATIONS: EXPERIENCE IN DESIGNING AND OPERATION, PROSPECTS IN APPLICATION

    Directory of Open Access Journals (Sweden)

    N. V. Karnitsky

    2014-01-01

    Full Text Available The paper has reviewed main world tendencies in power consumption and power system structure. Main schemes of combined cycle gas turbines have been considered in the paper. The paper contains an operational analysis of CCGT blocks that are operating within the Belarusian energy system. The analysis results have been given in tables showing main operational indices of power blocks

  13. Mine management system based on PDCA cycle

    Science.gov (United States)

    Wang, Yunliang

    2017-10-01

    The scientific and effective management of mining enterprises has been a major problem for managers. And as modern technical equipment is continuously equipped to the mine, the traditional way of management has been unable to meet the needs, which causes many problems. In response to these questions, we apply PDCA cycle management patterns to mining enterprises in this paper, and establish a scientific and effective management system. After that the efficiency of mine production is greatly improved under the premise of safe production.

  14. Combined gas-steam turbine cycle using coal derived liquid fuel - A viable alternative to direct combustion of coal

    Science.gov (United States)

    Tabi, R.; Mesko, J. E.

    An alternative to direct coal-combustion for electric power generation is liquefaction of coal prior to combustion in a combined gas-steam turbine plant. For optimization of the overall efficiency of the power plant, individual subsystem efficiencies must be analyzed, but the prevailing energy analysis based on the first law of thermodynamics is insufficient for this purpose and can be misleading. The paper presents a complete thermodynamic analysis of an 873 MWe combined gas-steam turbine cycle, which utilizes semiclean fuel from the H-Coal process.

  15. CO2-free power generation in combined cycles-Integration of post-combustion separation of carbon dioxide in the steam cycle

    International Nuclear Information System (INIS)

    Moeller, Bjoern Fredriksson; Assadi, Mohsen; Potts, Ian

    2006-01-01

    Ever since the release of the Kyoto protocol the demand for CO 2 -free processes have been increasing. One of the most expanding sources of electric power in the industrialised world today is the gas-fired combined cycle, combining high efficiency and low investment cost. In this paper, the integration of a post-combustion CO 2 -separation unit into a combined cycle is studied from a thermodynamic and economic point-of-view. A standard dual-pressure combined cycle is chosen as a reference cycle. It is compared to a dual-pressure combined cycle and a triple-pressure combined cycle with the lowest pressure level producing steam for a CO 2 -separation unit. The steam pressure levels in the different cycles are optimised for maximum efficiency and minimum specific cost, respectively, using genetic algorithms. The efficiency drop due to CO 2 -separation is approximately 8% points, from 54 to 46%. The specific cost of the power plant is expected to increase with almost 100% and the cost of electricity with approximately 30%. In several countries a carbon dioxide tax is already introduced as an incentive for more efficient power cycles and use of fuels with lower content of coal. The result above implies that the level of such a tax would be in the order of 30% of the price of electricity to encourage CO 2 -free power generation

  16. Thermodynamic Analyses of Biomass Gasification Integrated Externally Fired, Post-Firing and Dual-Fuel Combined Cycles

    Directory of Open Access Journals (Sweden)

    Saeed Soltani

    2015-01-01

    Full Text Available In the present work, the results are reported of the energy and exergy analyses of three biomass-related processes for electricity generation: the biomass gasification integrated externally fired combined cycle, the biomass gasification integrated dual-fuel combined cycle, and the biomass gasification integrated post-firing combined cycle. The energy efficiency for the biomass gasification integrated post-firing combined cycle is 3% to 6% points higher than for the other cycles. Although the efficiency of the externally fired biomass combined cycle is the lowest, it has an advantage in that it only uses biomass. The energy and exergy efficiencies are maximized for the three configurations at particular values of compressor pressure ratios, and increase with gas turbine inlet temperature. As pressure ratio increases, the mass of air per mass of steam decreases for the biomass gasification integrated post-firing combined cycle, but the pressure ratio has little influence on the ratio of mass of air per mass of steam for the other cycles. The gas turbine exergy efficiency is the highest for the three configurations. The combustion chamber for the dual-fuel cycle exhibits the highest exergy efficiency and that for the post-firing cycle the lowest. Another benefit of the biomass gasification integrated externally fired combined cycle is that it exhibits the highest air preheater and heat recovery steam generator exergy efficiencies.

  17. Exergoeconomic analysis and optimization of an Integrated Solar Combined Cycle System (ISCCS) using genetic algorithm

    International Nuclear Information System (INIS)

    Baghernejad, A.; Yaghoubi, M.

    2011-01-01

    Research highlights: → We applied thermoeconomic concept for optimization of an Integrated Solar Combined Cycle System (ISCCS) using genetic algorithm. → Optimization process improves the total performance of the system in a way that the objective function is decreased by 10.98%, the exergetic efficiency of the system is increased from about 43.79% to 46.8% and the rate of fuel cost is decreased by 7.23%. → Cost of electricity produced by steam turbine and gas turbine in the optimum design condition of the ISCCS are about 7.1% and 1.17% lower with respect to the base case. → Increasing solar field operation periods from 1000 to 2000 hours per year reduces the unit cost of electricity produced by steam turbine about 14%. → The unit cost of electricity has a linear and remarkable increase with fuel cost. Also by increasing the system construction period from 3 to 6 years, the unit cost of electricity produced by steam turbine increased about 13%. -- Abstract: In this study, thermoeconomic concept is applied using genetic algorithm for optimization of an Integrated Solar Combined Cycle System (ISCCS) that produces 400 MW of electricity. Attempt is made to minimize objective function including investment cost of equipments and cost of exergy destruction. Optimization process carried out by using exergoeconomic principles and genetic algorithm. The developed code first validated with a thermal system and good comparison is observed. Then the analysis is made for the ISCCS, and it shows that objective function for the optimum operation reduced by about 11%. Also cost of electricity produced by steam turbine and gas turbine in the optimum design of the ISCCS are about 7.1% and 1.17% lower with respect to the base case. These objectives are achieved with 13.3% increase in capital investment. Finally, sensitivity analysis is carried out to study the effect of changes in the unit cost of electricity for the system important parameters such as interest rate, plant

  18. Towards a Life Cycle Based Chemical Alternative Assessment (LCAA)

    DEFF Research Database (Denmark)

    Jolliet, O.; Huang, L.; Overcash, Michael

    2017-01-01

    There is a need for an operational quantitative screening-level assessment of alternatives, that is life-cycle based and able to serve both Life cycle Assessment (LCA and chemical alternatives assessment (CAA). This presentation therefore aims to develop and illustrate a new approach called “Life...... Cycle Based Chemical Alternative Assessment (LCAA)” that will quantify exposure and life cycle impacts consistently and efficiently over the main life cycle stages. The new LCAA approach is illustrated though a proof-of-concept case study of alternative plasticizers in vinyl flooring. The proposed LCAA...... ingredient in the product, first-order inter-compartmental transfer fractions and a matrix approach to determine Product Intake Fractions, and c) toxicity-related outcomes are compared with other life cycle impacts to evaluate the relevance of different impact categories for different consumer product...

  19. Thermal energy storage for integrated gasification combined-cycle power plants

    Energy Technology Data Exchange (ETDEWEB)

    Drost, M.K.; Antoniak, Z.I.; Brown, D.R.; Somasundaram, S.

    1990-07-01

    There are increasingly strong indications that the United States will face widespread electrical power generating capacity constraints in the 1990s; most regions of the country could experience capacity shortages by the year 2000. The demand for new generating capacity occurs at a time when there is increasing emphasis on environmental concerns. The integrated gasification combined-cycle (IGCC) power plant is an example of an advanced coal-fired technology that will soon be commercially available. The IGCC concept has proved to be efficient and cost-effective while meeting all current environmental regulations on emissions; however, the operating characteristics of the IGCC system have limited it to base load applications. The integration of thermal energy storage (TES) into an IGCC plant would allow it to meet cyclic loads while avoiding undesirable operating characteristics such as poor turn-down capability, impaired part-load performance, and long startup times. In an IGCC plant with TES, a continuously operated gasifier supplies medium-Btu fuel gas to a continuously operated gas turbine. The thermal energy from the fuel gas coolers and the gas turbine exhaust is stored as sensible heat in molten nitrate salt; heat is extracted during peak demand periods to produce electric power in a Rankine steam power cycle. The study documented in this report was conducted by Pacific Northwest Laboratory (PNL) and consists of a review of the technical and economic feasibility of using TES in an IGCC power plant to produce intermediate and peak load power. The study was done for the US Department of Energy's (DOE) Office of Energy Storage and Distribution. 11 refs., 5 figs., 18 tabs.

  20. Integrated solar combined cycles using gas turbines with partial recuperation and solar integration at different pressure levels

    Science.gov (United States)

    Rovira, Antonio; Sánchez, Consuelo; Fernández, Santiago; Muñoz, Marta; Barbero, Rubén

    2017-06-01

    This work studies and compares two alternatives to improve the solar-to-electricity energy conversion efficiency in integrated solar combined cycle power plants (ISCC), which are based on the use of combined cycles including partial recuperative gas turbines. Each alternative has been integrated into dual and triple pressure levels with reheat heat recovery steam generators (HRSG). Partial recuperation conveys lower heat recovery at the steam generator than in conventional plants, because each MW exchanged in the recuperator is not available at the HRSG. This thermal power decrease at the HRSG may be overcome by the integration of solar energy that is implemented using parabolic trough collectors. Moreover, with such an implementation each solar thermal MW integrated allows a MW of heat recuperation and, thus a MW of fossil fuel saving, thus the solar heat-to-electricity energy conversion rate may reach values up to 50 %, which makes the proposal interesting.

  1. Life cycle environmental impacts of wastewater-based algal biofuels.

    Science.gov (United States)

    Mu, Dongyan; Min, Min; Krohn, Brian; Mullins, Kimberley A; Ruan, Roger; Hill, Jason

    2014-10-07

    Recent research has proposed integrating wastewater treatment with algae cultivation as a way of producing algal biofuels at a commercial scale more sustainably. This study evaluates the environmental performance of wastewater-based algal biofuels with a well-to-wheel life cycle assessment (LCA). Production pathways examined include different nutrient sources (municipal wastewater influent to the activated sludge process, centrate from the sludge drying process, swine manure, and freshwater with synthetic fertilizers) combined with emerging biomass conversion technologies (microwave pyrolysis, combustion, wet lipid extraction, and hydrothermal liquefaction). Results show that the environmental performance of wastewater-based algal biofuels is generally better than freshwater-based algal biofuels, but depends on the characteristics of the wastewater and the conversion technologies. Of 16 pathways compared, only the centrate cultivation with wet lipid extraction pathway and the centrate cultivation with combustion pathway have lower impacts than petroleum diesel in all environmental categories examined (fossil fuel use, greenhouse gas emissions, eutrophication potential, and consumptive water use). The potential for large-scale implementation of centrate-based algal biofuel, however, is limited by availability of centrate. Thus, it is unlikely that algal biofuels can provide a large-scale and environmentally preferable alternative to petroleum transportation fuels without considerable improvement in current production technologies. Additionally, the cobenefit of wastewater-based algal biofuel production as an alternate means of treating various wastewaters should be further explored.

  2. Assessment of Environmental and Economic Impacts of Vine-Growing Combining Life Cycle Assessment, Life Cycle Costing and Multicriterial Analysis

    Directory of Open Access Journals (Sweden)

    Giacomo Falcone

    2016-08-01

    Full Text Available The wine sector is going through a significant evolution dealing with the challenges of competition issues in international markets and with necessary commitments to sustainability improvement. In the wine supply chain, the agricultural phase represents a potential source of pollution and costs. From the farmers’ point of view, these contexts require them to be more attentive and find a compromise among environmental benefits, economic benefits, and costs linked to farming practices. This paper aims to make a sustainability assessment of different wine-growing scenarios located in Calabria (Southern Italy that combines conflicting insights, i.e., environmental and economic ones, by applying Life Cycle Assessment (LCA and Life Cycle Costing (LCC to identify the main hotspots and select the alternative scenarios closest to the ideal solution through the VIKOR multicriteria method. In particular, the latter allowed us to obtain synthetic indices for a two-dimensional sustainability assessment. Conventional practices associated to the espalier training system represent the best compromise from both environmental and economic points of view, due to the higher yield per hectare. The choices regarding Functional Unit (FU and indicators were shown to have a high influence on results.

  3. Feature selection based classifier combination approach for ...

    Indian Academy of Sciences (India)

    based classifier combination is the simplest method in which final decision is that class for which maximum (greater than N/2) participating classifier vote, where N is the number of classifiers. 3.2b Decision templates: The method based on decision template, (Kuncheva et al 2001) firstly creates DT for each class using ...

  4. Feature selection based classifier combination approach for ...

    Indian Academy of Sciences (India)

    3.2c Dempster-Shafer rule based classifier combination: Dempster–Shafer (DS) method is based on the evidence theory, proposed by Glen Shafer as a way to represent cognitive knowledge. Here the probability is obtained using belief function instead of using the Bayesian distribution. Prob- ability values are assigned to a ...

  5. Energetic and Exergetic Analysis of Combined Cycle Power Plant: Part-1 Operation and Performance

    Directory of Open Access Journals (Sweden)

    Abdulrahman Almutairi

    2015-12-01

    Full Text Available Energetic and exergetic analyses are conducted using operating data for Sabiya, a combined cycle power plant (CCPP with an advanced triple pressure reheat heat recovery steam generator (HRSG. Furthermore, a sensitivity analysis is carried out on the HRSG using a recent approach to differentiate between the sources of irreversibility. The proposed system was modelled using the IPSEpro software and further validated by the manufacturer’s data. The performance of the Sabiya CCPP was examined for different climatic conditions, pressure ratios, pinch point temperatures, high-pressure steam, and condenser pressure values. The results confirmed that 60.9% of the total exergy destruction occurs in the combustion chamber, which constitutes the main source of irreversibilities within a system. The exergy destruction was significantly affected by both the pressure ratio and the high-pressure steam, where the relation between them was seen to be inversely proportional. The high-pressure stage contributes about 50% of the exergy destruction within the HRSG compared to other stages and the reheat system, due to the high temperature difference between the streams and the large number of components, which leads to high energy loss to the surroundings. Numerous possibilities for improving the CCPP’s performance are introduced, based on the obtained results.

  6. Wabash River Coal Gasification Combined Cycle Repowering Project: Clean Coal Technology Program. Environmental Assessment

    Energy Technology Data Exchange (ETDEWEB)

    1993-05-01

    The proposed project would result in a combined-cycle power plant with lower emissions and higher efficiency than most existing coal-fired power plants of comparable size. The net plant heat rate (energy content of the fuel input per useable electrical generation output; i.e., Btu/kilowatt hour) for the new repowered unit would be a 21% improvement over the existing unit, while reducing SO{sub 2} emissions by greater than 90% and limiting NO{sub x} emissions by greater than 85% over that produced by conventional coal-fired boilers. The technology, which relies on gasified coal, is capable of producing as much as 25% more electricity from a given amount of coal than today`s conventional coal-burning methods. Besides having the positive environmental benefit of producing less pollutants per unit of power generated, the higher overall efficiency of the proposed CGCC project encourages greater utilization to meet base load requirements in order to realize the associated economic benefits. This greater utilization (i.e., increased capacity factor) of a cleaner operating plant has global environmental benefits in that it is likely that such power would replace power currently being produced by less efficient plants emitting a greater volume of pollutants per unit of power generated.

  7. Wabash River Coal Gasification Combined Cycle Repowering Project: Clean Coal Technology Program

    International Nuclear Information System (INIS)

    1993-05-01

    The proposed project would result in a combined-cycle power plant with lower emissions and higher efficiency than most existing coal-fired power plants of comparable size. The net plant heat rate (energy content of the fuel input per useable electrical generation output; i.e., Btu/kilowatt hour) for the new repowered unit would be a 21% improvement over the existing unit, while reducing SO 2 emissions by greater than 90% and limiting NO x emissions by greater than 85% over that produced by conventional coal-fired boilers. The technology, which relies on gasified coal, is capable of producing as much as 25% more electricity from a given amount of coal than today's conventional coal-burning methods. Besides having the positive environmental benefit of producing less pollutants per unit of power generated, the higher overall efficiency of the proposed CGCC project encourages greater utilization to meet base load requirements in order to realize the associated economic benefits. This greater utilization (i.e., increased capacity factor) of a cleaner operating plant has global environmental benefits in that it is likely that such power would replace power currently being produced by less efficient plants emitting a greater volume of pollutants per unit of power generated

  8. Analysis and Optimization of a Compressed Air Energy Storage—Combined Cycle System

    Directory of Open Access Journals (Sweden)

    Wenyi Liu

    2014-06-01

    Full Text Available Compressed air energy storage (CAES is a commercial, utility-scale technology that provides long-duration energy storage with fast ramp rates and good part-load operation. It is a promising storage technology for balancing the large-scale penetration of renewable energies, such as wind and solar power, into electric grids. This study proposes a CAES-CC system, which is based on a conventional CAES combined with a steam turbine cycle by waste heat boiler. Simulation and thermodynamic analysis are carried out on the proposed CAES-CC system. The electricity and heating rates of the proposed CAES-CC system are lower than those of the conventional CAES by 0.127 kWh/kWh and 0.338 kWh/kWh, respectively, because the CAES-CC system recycles high-temperature turbine-exhausting air. The overall efficiency of the CAES-CC system is improved by approximately 10% compared with that of the conventional CAES. In the CAES-CC system, compressing intercooler heat can keep the steam turbine on hot standby, thus improving the flexibility of CAES-CC. This study brought about a new method for improving the efficiency of CAES and provided new thoughts for integrating CAES with other electricity-generating modes.

  9. Biomass Integrated Gasification Combined Cycle for heat and power at ethanol plants

    Energy Technology Data Exchange (ETDEWEB)

    De Kam, Matthew J.; Vance Morey, R. [Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave, St. Paul, MN 55108 (United States); Tiffany, Douglas G. [Department of Applied Economics, University of Minnesota, 1994 Buford Avenue St. Paul, MN 55108 (United States)

    2009-07-15

    Biomass Integrated Gasification Combined Cycle (BIGCC) technology can be used to generate process heat and significant amounts of electricity at dry-grind ethanol facilities by utilizing the ethanol process co-products and other biomass sources. These systems can reduce fuel costs for ethanol plants, improve the renewable energy balance of dry-grind ethanol production, and provide reliable renewable electricity for process use and for sale to the local utility. An Aspen Plus model of the dry-grind ethanol process is used as the basis for a subsequent gasification system model. A twin fluidized bed steam gasification configuration based on the SilvaGas process is used to generate synthesis gas. The results show that a dry-grind ethanol facility with a capacity of 190 million liters per year could produce 30.4 MW{sub e} of power while supplying all its process heat needs using ethanol co-products and corn cobs. This configuration results in a three fold improvement in the amount of renewable energy produced per unit of fossil energy used compared to a conventional ethanol production process using natural gas. (author)

  10. The effectiveness of combined-cycle power plants hot startups simulating

    Science.gov (United States)

    Radin, Yu. A.; Kontorovich, T. S.; Molchanov, K. A.

    2015-09-01

    Activities aimed at substantiating the maneuverability characteristics of power-generating equipment installed at district heating power plants (DHPP) and especially at combined-cycle power plants (CCPPs) are quite topical for the modern conditions and involve calculations of thermally stressed state and analysis of the cyclic strength of steam path critical elements at different loading rates. Until recently, such problems have been solved in two possible ways: based on the results of tests carried out on operating equipment and using the mathematical models of heavily stressed parts of CCPP equipment. In this article, preference is given to the second way. The results of mathematical modeling represented as time dependences of the temperature state of equipment critical parts were taken as initial data for calculating their thermally stressed state and for analyzing their damageability according to the criterion of the equivalent operating hours. This criterion is an integral indicator characterizing the extent of damage accumulated in equipment parts and can be used for elaborating equipment maintenance programs. A dependence of the equivalent operating hours on the initial temperature of the metal of the high-pressure steam superheater's outlet header, the component imposing the strongest limitations on the power unit loading rate, is obtained. It is shown that the number of equivalent operating hours of the CCPP steam circuit part equipment accumulated during hot startups does not have any essential effect on the equipment service life (heat-recovery steam generators, steam turbine, and steam lines).

  11. Energy and exergy analysis of a combined refrigeration and waste heat driven organic Rankine cycle system

    Directory of Open Access Journals (Sweden)

    Cihan Ertugrul

    2017-01-01

    Full Text Available Energy and exergy analysis of a combined refrigeration and waste heat driven organic Rankine cycle system were studied theoretically in this paper. In order to complete refrigeration process, the obtained kinetic energy was supplied to the compressor of the refrigeration cycle. Turbine, in power cycle, was driven by organic working fluid that exits boiler with high temperature and pressure. Theoretical performances of proposed system were evaluated employing five different organic fluids which are R123, R600, R245fa, R141b, and R600a. Moreover, the change of thermal and exergy efficiencies were examined by changing the boiling, condensing, and evaporating temperatures. As a result of energy and exergy analysis of the proposed system, most appropriate organic working fluid was determined as R141b.

  12. Environmental impact efficiency of natural gas combined cycle power plants: A combined life cycle assessment and dynamic data envelopment analysis approach.

    Science.gov (United States)

    Martín-Gamboa, Mario; Iribarren, Diego; Dufour, Javier

    2018-02-15

    The energy sector is still dominated by the use of fossil resources. In particular, natural gas represents the third most consumed resource, being a significant source of electricity in many countries. Since electricity production in natural gas combined cycle (NGCC) plants provides some benefits with respect to other non-renewable technologies, it is often seen as a transitional solution towards a future low‑carbon power generation system. However, given the environmental profile and operational variability of NGCC power plants, their eco-efficiency assessment is required. In this respect, this article uses a novel combined Life Cycle Assessment (LCA) and dynamic Data Envelopment Analysis (DEA) approach in order to estimate -over the period 2010-2015- the environmental impact efficiencies of 20 NGCC power plants located in Spain. A three-step LCA+DEA method is applied, which involves data acquisition, calculation of environmental impacts through LCA, and the novel estimation of environmental impact efficiency (overall- and term-efficiency scores) through dynamic DEA. Although only 1 out of 20 NGCC power plants is found to be environmentally efficient, all plants show a relatively good environmental performance with overall eco-efficiency scores above 60%. Regarding individual periods, 2011 was -on average- the year with the highest environmental impact efficiency (95%), accounting for 5 efficient NGCC plants. In this respect, a link between high number of operating hours and high environmental impact efficiency is observed. Finally, preliminary environmental benchmarks are presented as an additional outcome in order to further support decision-makers in the path towards eco-efficiency in NGCC power plants. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Performance simulation of a basic combined cycle cogeneration system. Paper no. IGEC-1-ID20

    International Nuclear Information System (INIS)

    Law, B.; Reddy, B.V.

    2005-01-01

    Combined cycle power plants with a gas turbine topping cycle and a steam turbine bottoming cycle are being employed for power generation. It would be advantageous if they are used to produce power and process heat in cogeneration mode, from the same fuel source. The objective of the present work is to analyze and simulate a natural gas fired combined cycle cogeneration (CCC) unit and to investigate the effect of different operating conditions, with the goal of improving the plant performance and efficiency. In the present work, two units are examined, a basic unit and a unit with supplementary firing. The operating conditions investigated include, pressure ratio, gas turbine inlet temperature, component efficiencies and process heat load variation. The preliminary results indicate that a CCC unit should be designed to operate with the highest possible pressure ratio in order to optimize performance. It is established that a CCC unit should employ gas turbines that operate at the maximum allowable temperature. This will optimize the system performance and increase all of the outputs of the system. Supplementary firing is an attractive option for industries with varying process heat load requirements. (author)

  14. Environmental Assessment for the Warren Station externally fired combined cycle demonstration project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-04-01

    The proposed Penelec project is one of 5 projects for potential funding under the fifth solicitation under the Clean Coal Technology program. In Penelec, two existing boilers would be replaced at Warren Station, PA; the new unit would produce 73 MW(e) in a combined cycle mode (using both gas-fired and steam turbines). The project would fill the need for a full utility-size demonstration of externally fire combined cycle (EFCC) technology as the next step toward commercialization. This environmental assessment was prepared for compliance with NEPA; its purpose is to provide sufficient basis for determining whether to prepare an environmental impact statement or to issue a finding of no significant impact. It is divided into the sections: purpose and need for proposed action; alternatives; brief description of affected environment; environmental consequences, including discussion of commercial operation beyond the demonstration period.

  15. TEPCO`s Yokohama 7 and 8 leading the world in advanced combined-cycle power

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, D.L. [GE Power Systems (United States)

    1995-12-31

    TEPCO has contracted with GE to design and furnish power plant equipment for a 2800-MW addition to the Yokohama thermal power station, utilising the latest, state-of-the-art combined-cycle technology to achieve maximum efficiency and reliability with low environmental impact. The plant will consist of 8 combined-cycle stages and will have a gross thermal efficiency of 54%. NO{sub x} concentrations of 5 ppmvd or less at the stack will be achieved through the use of advanced dry-low-NO{sub x} combustion technology in the gas turbines, and selective catalytic reduction technology. Initial firing of the first unit es expected by the end of 1995, with commercial operation of the eight stages being phased in during 1996, 1997, and 1998.

  16. Design calculation of three-loop combined-cycle plants with steam reheating

    Science.gov (United States)

    Trukhnii, A. D.; Parshina, N. S.

    2010-02-01

    We describe a procedure for carrying out an end-to-end calculation of the parameters of media and technical and economic indicators of three-loop heat-recovery-type combined-cycle plants with steam reheating that makes it possible to determine the parameters of gases and working fluid of a heat-recovery boiler and the thermal power of its heating surfaces, and to carry out an approximate calculation of the steam turbine for compartments and then for stages at the stage of design calculations using the parameters of gases exhausted from the gas turbine unit as initial data. The procedure is implemented in the form of a computer program in the DELPHI environment and makes it possible to quickly and reliably optimize a combined-cycle plant’s thermal circuit and steam turbine design.

  17. Thermodynamic analysis and conceptual design for partial coal gasification air preheating coal-fired combined cycle

    Science.gov (United States)

    Xu, Yue; Wu, Yining; Deng, Shimin; Wei, Shirang

    2004-02-01

    The partial coal gasification air pre-heating coal-fired combined cycle (PGACC) is a cleaning coal power system, which integrates the coal gasification technology, circulating fluidized bed technology, and combined cycle technology. It has high efficiency and simple construction, and is a new selection of the cleaning coal power systems. A thermodynamic analysis of the PGACC is carried out. The effects of coal gasifying rate, pre-heating air temperature, and coal gas temperature on the performances of the power system are studied. In order to repower the power plant rated 100 MW by using the PGACC, a conceptual design is suggested. The computational results show that the PGACC is feasible for modernizing the old steam power plants and building the new cleaning power plants.

  18. Chronoamperometry-Based Redox Cycling for Application to Immunoassays.

    Science.gov (United States)

    Lee, Ga-Yeon; Park, Jun-Hee; Chang, Young Wook; Cho, Sungbo; Kang, Min-Jung; Pyun, Jae-Chul

    2018-01-26

    In this work, the chronoamperometry-based redox cycling of 3,3',5,5'-tetramethylbenzidine (TMB) was performed by using interdigitated electrode (IDE). The signal was obtained from two sequential chronoamperometric profiles: (1) with the generator at the oxidative potential of TMB and the collector at the reductive potential of TMB, and (2) with the generator at the reductive potential of TMB and the collector at the oxidative potential of TMB. The chronoamperometry-based redox cycling (dual mode) showed a sensitivity of 1.49 μA/OD, and the redox cycling efficiency was estimated to be 94% (n = 10). The sensitivities of conventional redox cycling with the same interdigitated electrode and chronoamperometry using a single working electrode (single mode) were estimated to be 0.67 μA/OD and 0.18 μA/OD, respectively. These results showed that the chronoamperometry-based redox cycling (dual mode) could be more effectively used to quantify the oxidized TMB than other amperometric methods. The chronoamperometry-based redox cycling (dual mode) was applied to immunoassays using a commercial ELISA kit for medical diagnosis of the human hepatitis B virus surface antigen (hHBsAg). Finally, the chronoamperometry-based redox cycling (dual mode) provided more than a 10-fold higher sensitivity than conventional chronoamperometry using a single working electrode (single mode) when applied to a commercial ELISA kit for medical diagnosis of hHBsAg.

  19. Thermoeconomic Analysis and Optimization of a New Combined Supercritical Carbon Dioxide Recompression Brayton/Kalina Cycle

    Directory of Open Access Journals (Sweden)

    S. Mohammad S. Mahmoudi

    2016-10-01

    Full Text Available A new combined supercritical CO2 recompression Brayton/Kalina cycle (SCRB/KC is proposed. In the proposed system, waste heat from a supercritical CO2 recompression Brayton cycle (SCRBC is recovered by a Kalina cycle (KC to generate additional electrical power. The performances of the two cycles are simulated and compared using mass, energy and exergy balances of the overall systems and their components. Using the SPECO (Specific Exergy Costing approach and employing selected cost balance equations for the components of each system, the total product unit costs of the cycles are obtained. Parametric studies are performed to investigate the effects on the SCRB/KC and SCRBC thermodynamic and thermoeconomic performances of key decision parameters. In addition, considering the exergy efficiency and total product unit cost as criteria, optimization is performed for the SCRBC and SCRB/KC using Engineering Equation Solver software. The results indicate that the maximum exergy efficiency of the SCRB/KC is higher than that of the SCRBC by up to 10%, and that the minimum total product unit cost of the SCRB/KC is lower than that of the SCRBC by up to 4.9%.

  20. Energetic and exergetic analysis of combined cycle Energas Boca de Jaruco

    International Nuclear Information System (INIS)

    Dominguez, F. J.; Tapanez, A.; Castillo, E. del; Castillo, R.; Perez, R.

    2015-01-01

    The work shows the energy and exergy evaluation of the combined cycle Energas Boca de Jaruco, which consists of five gas turbines 30 MWh five heat recovery steam OTSGs type and a steam turbine of 150 MW. This evaluation is performed without additional burning and for different percentages of utilization of these burners. The results allow to have a criterion of the efficiency of the system with and without supplementary burned, which can define strategies most appropriate system operation. (full text)

  1. Simulation of an Integrated Gasification Combined Cycle with Chemical-Looping Combustion and CO2 sequestration

    OpenAIRE

    Jiménez Alvaro, Ángel; López Paniagua, Ignacio; González Fernández, M. Celina; Rodríguez Martín, Javier; Nieto Carlier, Rafael

    2014-01-01

    Chemical-looping combustion allows an integration of CO2 capture in a thermal power plant without energy penalty; secondly, a less exergy destruction in the combustion chemical transformation is achieved, leading to a greater overall thermal efficiency. This paper focus on the study of the energetic performance of this concept of combustion in an integrated gasification combined cycle power plant when synthesis gas is used as fuel for the gas turbines. After thermodynamic modelling and optimi...

  2. Integrated gasification combined-cycle research development and demonstration activities in the US

    Energy Technology Data Exchange (ETDEWEB)

    Ness, H.M.; Brdar, R.D.

    1996-09-01

    The United States Department of Energy (DOE)`s Office of Fossil Energy, Morgantown Energy Technology Center, is managing a research development and demonstration (RD&D) program that supports the commercialization of integrated gasification combined-cycle (IGCC) advanced power systems. This overview briefly describes the supporting RD&D activities and the IGCC projects selected for demonstration in the Clean Coal Technology (CCT) Program.

  3. Generating power at high efficiency combined cycle technology for sustainable energy production

    CERN Document Server

    Jeffs, E

    2008-01-01

    Combined cycle technology is used to generate power at one of the highest levels of efficiency of conventional power plants. It does this through primary generation from a gas turbine coupled with secondary generation from a steam turbine powered by primary exhaust heat. Generating power at high efficiency thoroughly charts the development and implementation of this technology in power plants and looks to the future of the technology, noting the advantages of the most important technical features - including gas turbines, steam generator, combined heat and power and integrated gasification com

  4. Analysis of energetic and exergetic efficiency, and environmental benefits of biomass integrated gasification combined cycle technology.

    Science.gov (United States)

    Mínguez, María; Jiménez, Angel; Rodríguez, Javier; González, Celina; López, Ignacio; Nieto, Rafael

    2013-04-01

    The problem of the high carbon dioxide emissions linked to power generation makes necessary active research on the use of biofuels in gas turbine systems as a promising alternative to fossil fuels. Gasification of biomass waste is particularly of interest in obtaining a fuel to be run in gas turbines, as it is an efficient biomass-to-biofuel conversion process, and an integration into a combined cycle power plant leads to a high performance with regard to energetic efficiency. The goal of this study was to carry out an energetic, exergetic and environmental analysis of the behaviour of an integrated gasification combined cycle (IGCC) plant fuelled with different kinds of biomass waste by means of simulations. A preliminary economic study is also included. Although a technological development in gasification technology is necessary, the results of simulations indicate a high technical and environmental interest in the use of biomass integrated gasification combined cycle (BioIGCC) systems for large-scale power generation from biomass waste.

  5. Technical and economic assessment of the integrated solar combined cycle power plants in Iran

    International Nuclear Information System (INIS)

    Soltani Hosseini, M.; Hosseini, R.; Valizadeh, G.H.

    2002-01-01

    Thermal efficiency, capacity factor, environmental considerations, investment cost, fuel and O and M costs are the main parameters for technical and economic assessment of solar power plants. This analysis has shown that the Integrated Solar Combined Cycle System with 67 MW e solar field(ISCCS-67) is the most suitable plan for the first solar power plant in Iran. The Levelized Energy Costs of combined cycle and ISCCS-67 power plants would be equal if 49 million dollars of ISCCS-67 capital cost supplied by the international environmental organizations such as Global Environmental Facilities and World Bank. This study shows that an ISCCS-67 saves 59 million dollars in fuel consumption and reduces about 2.4 million ton in CO 2 emission during 30 years operating period. Increasing of steam turbine capacity by 50%, and 4% improvement in overall efficiency are other advantages of iSCCS-67 power plant. The LEC of ISCCS-67 is 10% and so 33% lower than the combined cycle and gas turbine, respectively, at the same capacity factor with consideration of environmental costs

  6. Numerical analysis and field study of time dependent exergy-energy of a gas-steam combined cycle

    Directory of Open Access Journals (Sweden)

    Barari Bamdad

    2012-01-01

    Full Text Available In this study, time dependent exergy analysis of the Fars Combined Power Plant Cycle has been investigated. Exergy analysis has been used for investigating each part of actual combined cycle by considering irreversibility from Apr 2006 to Oct 2010. Performance analysis has been done for each part by evaluating exergy destruction in each month. By using of exergy analysis, aging of each part has been evaluated respect to time duration. In addition, the rate of lost work for each month has been calculated and variation of this parameter has been considered as a function of aging rate. Finally, effects of exergy destruction of each part have been investigated on exergy destruction of whole cycle. Entire analysis has been done for Unit 3 and 4 of gas turbine cycle which combined by Unit B of steam cycle in Fars Combined Power Plant Cycle located in Fars province in Iran.

  7. Life-Cycle Thinking in Inquiry-Based Sustainability Education--Effects on Students' Attitudes towards Chemistry and Environmental Literacy

    Science.gov (United States)

    Juntunen, Marianne; Aksela, Maija

    2013-01-01

    The aim of the present study is to improve the quality of students' environmental literacy and sustainability education in chemistry teaching by combining the socio-scientific issue of life-cycle thinking with inquiry-based learning approaches. This case study presents results from an inquiry-based life-cycle thinking project: an interdisciplinary…

  8. Performance analysis of an Integrated Solar Combined Cycle using Direct Steam Generation in parabolic trough collectors

    International Nuclear Information System (INIS)

    Montes, M.J.; Rovira, A.; Munoz, M.; Martinez-Val, J.M.

    2011-01-01

    Highlights: → Solar hybridization improves the performance of CCGT in a very hot and dry weather. → The scheme analyzed is a DSG parabolic trough field coupled to the Rankine cycle. → An annual simulation has been carried out for two locations: Almeria and Las Vegas. → Economical analysis shows that this scheme is a cheaper way to exploit solar energy. → For that, solar hybridization must be limited to a small fraction of the CCGT power. - Abstract: The contribution of solar thermal power to improve the performance of gas-fired combined cycles in very hot and dry environmental conditions is analyzed in this work, in order to assess the potential of this technique, and to feature Direct Steam Generation (DSG) as a well suited candidate for achieving very good results in this quest. The particular Integrated Solar Combined Cycle (ISCC) power plant proposed consists of a DSG parabolic trough field coupled to the bottoming steam cycle of a Combined Cycle Gas Turbine (CCGT) power plant. For this analysis, the solar thermal power plant performs in a solar dispatching mode: the gas turbine always operates at full load, only depending on ambient conditions, whereas the steam turbine is somewhat boosted to accommodate the thermal hybridization from the solar field. Although the analysis is aimed to studying such complementary effects in the widest perspective, two relevant examples are given, corresponding to two well-known sites: Almeria (Spain), with a mediterranean climate, and Las Vegas (USA), with a hot and dry climate. The annual simulations show that, although the conventional CCGT power plant works worse in Las Vegas, owing to the higher temperatures, the ISCC system operates better in Las Vegas than in Almeria, because of solar hybridization is especially well coupled to the CCGT power plant in the frequent days with great solar radiation and high temperatures in Las Vegas. The complementary effect will be clearly seen in these cases, because the thermal

  9. Technoeconomy of different solid oxide fuel cell based hybrid cycle

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2014-01-01

    Gas turbine, steam turbine and heat engine (Stirling engine) is used as bottoming cycle for a solid oxide fuel cell plant to compare different plants efficiencies, CO2 emissionsand plants cost in terms of $/kW. Each plant is then integrated with biomass gasification and finally six plants...... configurations are compared with each other. Technoeconomy is used when calculating the cost if the plants. It is found that when a solid oxide fuel cell plant is combined with a gas turbine cycle then the plant efficiency will be the highest one while if a biomass gasification plant is integrated...... with these hybrid cycles then integrated biomass gasification with solid oxide fuel cell and steam cycle will have the highest plant efficiency. The cost of solid oxide fuel cell with steam plant is found to be the lowest one with a value of about 1030$/kW....

  10. Feature selection based classifier combination approach for ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Feature selection based classifier combination approach for handwritten Devanagari numeral recognition. Pratibha Singh Ajay Verma ... ensemble of classifiers. The main contribution of the proposed method is that, the method gives quite efficient results utilizing only 10% patterns of the available dataset.

  11. Combinational Services for NGN based IPTV

    NARCIS (Netherlands)

    Mikóczy, E.; Schumann, S.; Stokking, H.M.; Deventer, M.O. van; Niamut, O.A.

    2009-01-01

    This paper describes the general concept of combinational/blended services for IP-based Television (IPTV) services in next generation networks towards its service oriented architecture concept (SOA). Besides introducing general approaches of service reusability (SOA concepts), the service enables

  12. Aspen Plus simulation of biomass integrated gasification combined cycle systems at corn ethanol plants

    International Nuclear Information System (INIS)

    Zheng, Huixiao; Kaliyan, Nalladurai; Morey, R. Vance

    2013-01-01

    Biomass integrated gasification combined cycle (BIGCC) systems and natural gas combined cycle (NGCC) systems are employed to provide heat and electricity to a 0.19 hm 3 y −1 (50 million gallon per year) corn ethanol plant using different fuels (syrup and corn stover, corn stover alone, and natural gas). Aspen Plus simulations of BIGCC/NGCC systems are performed to study effects of different fuels, gas turbine compression pressure, dryers (steam tube or superheated steam) for biomass fuels and ethanol co-products, and steam tube dryer exhaust treatment methods. The goal is to maximize electricity generation while meeting process heat needs of the plant. At fuel input rates of 110 MW, BIGCC systems with steam tube dryers provide 20–25 MW of power to the grid with system thermal efficiencies (net power generated plus process heat rate divided by fuel input rate) of 69–74%. NGCC systems with steam tube dryers provide 26–30 MW of power to the grid with system thermal efficiencies of 74–78%. BIGCC systems with superheated steam dryers provide 20–22 MW of power to the grid with system thermal efficiencies of 53–56%. The life-cycle greenhouse gas (GHG) emission reduction for conventional corn ethanol compared to gasoline is 39% for process heat with natural gas (grid electricity), 117% for BIGCC with syrup and corn stover fuel, 124% for BIGCC with corn stover fuel, and 93% for NGCC with natural gas fuel. These GHG emission estimates do not include indirect land use change effects. -- Highlights: •BIGCC and natural gas combined cycle systems at corn ethanol plants are simulated. •The best performance results in 25–30 MW power to grid. •The best performance results in 74–78% system thermal efficiencies. •GHG reduction for corn ethanol with BIGCC systems compared to gasoline is over 100%

  13. Optimization of thermoelectric topping combined steam turbine cycles for energy economy

    International Nuclear Information System (INIS)

    Yazawa, Kazuaki; Koh, Yee Rui; Shakouri, Ali

    2013-01-01

    Highlights: • Thermoelectric on top of steam turbine cycle provides better energy economy. • There found an optimum partitioning temperature in between two engines. • Lower energy cost is found at the max-power at the beginning of operation. • Higher efficiency operation lowers the energy cost for longer hours. • Improving ZT provides a significant cost reduction for energy production. - Abstract: A mismatch between the fuel combustion temperature ∼2250 K (adiabatic) and the high pressure steam temperature up to 900 K, results in a large amount of thermodynamic losses in steam turbine (ST) cycles. A solid-state thermoelectric (TE) placed on top of a ST cycle will produce additional electrical power. By selecting the right materials for the TE generator for high temperature operation, the energy production from the same fuel consumption will increase. Recent nano-structured enhancements to the thermoelectric materials could provide practical performance benefits. We carried out a theoretical study on the optimization of the interface temperature connecting these two idealized engines for energy economy as a combined system. We also analytically studied the optimum point-of-operation between the maximum power output for minimizing the payback and the maximum efficiency to obtain the maximum fuel economy for each generator. The economic optimum ends up in a significant reduction in energy cost ($/kW h). The combined TE topping generator system provides a lower energy cost for any period of operational life and higher interface temperature compared to the ST cycle alone. The maximum power output is observed at around 700 K of interface temperature for 10,000 h of operation, while the minimum energy production cost from the combined system is observed at over 900 K with ZT = 1

  14. Energy-exergy analysis of compressor pressure ratio effects on thermodynamic performance of ammonia water combined cycle

    International Nuclear Information System (INIS)

    Mohtaram, Soheil; Chen, Wen; Zargar, T.; Lin, Ji

    2017-01-01

    Highlights: • Energy exergy analysis is conducted to find the effects of RP. • EES software is utilized to perform the detailed energy-exergy analyses. • Effects investigated through energy and exergy destruction, enthalpy, yields, etc. • Detailed results are reported showing the performance of gas and combined cycle. - Abstract: The purpose of this study is to investigate the effect of compressor pressure ratio (RP) on the thermodynamic performances of ammonia-water combined cycle through energy and exergy destruction, enthalpy temperature, yields, and flow velocity. The energy-exergy analysis is conducted on the ammonia water combined cycle and the Rankine cycle, respectively. Engineering Equation Solver (EES) software is utilized to perform the detailed analyses. Values and ratios regarding heat drop and exergy loss are presented in separate tables for different equipments. The results obtained by the energy-exergy analysis indicate that by increasing the pressure ratio compressor, exergy destruction of high-pressure compressors, intercooler, gas turbine and the special produced work of gas turbine cycle constantly increase and the exergy destruction of recuperator, in contrast, decreases continuously. In addition, the least amount of input fuel into the combined cycle is observed when the pressure ratio is no less than 7.5. Subsequently, the efficiency of the cycle in gas turbine and combined cycle is reduced because the fuel input into the combined cycle is increased.

  15. Predicting cycle 24 using various dynamo-based tools

    Directory of Open Access Journals (Sweden)

    M. Dikpati

    2008-02-01

    Full Text Available Various dynamo-based techniques have been used to predict the mean solar cycle features, namely the amplitude and the timings of onset and peak. All methods use information from previous cycles, including particularly polar fields, drift-speed of the sunspot zone to the equator, and remnant magnetic flux from the decay of active regions. Polar fields predict a low cycle 24, while spot zone migration and remnant flux both lead to predictions of a high cycle 24. These methods both predict delayed onset for cycle 24. We will describe how each of these methods relates to dynamo processes. We will present the latest results from our flux-transport dynamo, including some sensitivity tests and how our model relates to polar fields and spot zone drift methods.

  16. Selecting the process arrangement for preparing the gas turbine working fluid for an integrated gasification combined-cycle power plant

    Science.gov (United States)

    Ryzhkov, A. F.; Gordeev, S. I.; Bogatova, T. F.

    2015-11-01

    Introduction of a combined-cycle technology based on fuel gasification integrated in the process cycle (commonly known as integrated gasification combined cycle technology) is among avenues of development activities aimed at achieving more efficient operation of coal-fired power units at thermal power plants. The introduction of this technology is presently facing the following difficulties: IGCC installations are characterized by high capital intensity, low energy efficiency, and insufficient reliability and availability indicators. It was revealed from an analysis of literature sources that these drawbacks are typical for the gas turbine working fluid preparation system, the main component of which is a gasification plant. Different methods for improving the gasification plant chemical efficiency were compared, including blast air high-temperature heating, use of industrial oxygen, and a combination of these two methods implying limited use of oxygen and moderate heating of blast air. Calculated investigations aimed at estimating the influence of methods for achieving more efficient air gasification are carried out taking as an example the gasifier produced by the Mitsubishi Heavy Industries (MHI) with a thermal capacity of 500 MW. The investigation procedure was verified against the known experimental data. Modes have been determined in which the use of high-temperature heating of blast air for gasification and cycle air upstream of the gas turbine combustion chamber makes it possible to increase the working fluid preparation system efficiency to a level exceeding the efficiency of the oxygen process performed according to the Shell technology. For the gasification plant's configuration and the GTU working fluid preparation system be selected on a well-grounded basis, this work should be supplemented with technical-economic calculations.

  17. Coordinated optimization of the parameters of the cooled gas-turbine flow path and the parameters of gas-turbine cycles and combined-cycle power plants

    Science.gov (United States)

    Kler, A. M.; Zakharov, Yu. B.; Potanina, Yu. M.

    2014-06-01

    In the present paper, we evaluate the effectiveness of the coordinated solution to the optimization problem for the parameters of cycles in gas turbine and combined cycle power plants and to the optimization problem for the gas-turbine flow path parameters within an integral complex problem. We report comparative data for optimizations of the combined cycle power plant at coordinated and separate optimizations, when, first, the gas turbine and, then, the steam part of a combined cycle plant is optimized. The comparative data are presented in terms of economic indicators, energy-effectiveness characteristics, and specific costs. Models that were used in the present study for calculating the flow path enable taking into account, as a factor influencing the economic and energy effectiveness of the power plant, the heat stability of alloys from which the nozzle and rotor blades of gas-turbine stages are made.

  18. High-Efficiency Small-Scale Combined Heat and Power Organic Binary Rankine Cycles

    Directory of Open Access Journals (Sweden)

    Costante Mario Invernizzi

    2018-04-01

    Full Text Available Small-CHP (Combined Heat and Power systems are generally considered a valuable technological option to the conventional boilers, in a technology developed context. If small-CHP systems are associated with the use of renewable energies (biomass, for example they could play an important role in distributed generation even in developing countries or, in any case, where there are no extensive electricity networks. Traditionally the considered heat engines for micro- or mini-CHP are: the gas engine, the gas turbine (with internal combustion, the steam engine, engine working according to the Stirling and to the Rankine cycles, the last with organic fluids. In principle, also fuel cells could be used. In this paper, we focus on small size Rankine cycles (10–15 k W with organic working fluids. The assumed heat source is hot combustion gases at high temperature (900–950 ∘ C and we assume to use only single stages axial turbines. The need to work at high temperatures, limits the choice of the right organic working fluids. The calculation results show the limitation in the performances of simple cycles and suggest the opportunity to resort to complex (binary cycle configurations to achieve high net conversion efficiencies (15–16%.

  19. A life cycle assessment framework combining nutritional and environmental health impacts of diet: a case study on milk

    DEFF Research Database (Denmark)

    Stylianou, Katerina S.; Heller, Martin C.; Fulgoni III, Victor L.

    2016-01-01

    human health effects associated with the addition of one serving of fluid milk to the present average adult US diet. Epidemiology-based nutritional impacts and benefits linked to milk intake, such as colorectal cancer, stroke, and prostate cancer, were compared to selected environmental impacts......-LCA) framework that evaluates and compares in parallel the environmental and nutritional effects of foods or diets. We applied this framework to assess human health impacts, expressed in Disability Adjusted Life Years (DALYs), in a proof-of conceptcase study that investigated the environmental and nutritional......Purpose While there has been considerable effort to understand the environmental impact of a food or diet, nutritional effects are not usually included in food-related life cycle assessment (LCA). Methods We developed a novel Combined Nutritional and Environmental Life Cycle Assessment (CONE...

  20. Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 5: Combined gas-steam turbine cycles. [energy conversion efficiency in electric power plants

    Science.gov (United States)

    Amos, D. J.; Foster-Pegg, R. W.; Lee, R. M.

    1976-01-01

    The energy conversion efficiency of gas-steam turbine cycles was investigated for selected combined cycle power plants. Results indicate that it is possible for combined cycle gas-steam turbine power plants to have efficiencies several point higher than conventional steam plants. Induction of low pressure steam into the steam turbine is shown to improve the plant efficiency. Post firing of the boiler of a high temperature combined cycle plant is found to increase net power but to worsen efficiency. A gas turbine pressure ratio of 12 to 1 was found to be close to optimum at all gas turbine inlet temperatures that were studied. The coal using combined cycle plant with an integrated low-Btu gasifier was calculated to have a plant efficiency of 43.6%, a capitalization of $497/kW, and a cost of electricity of 6.75 mills/MJ (24.3 mills/kwh). This combined cycle plant should be considered for base load power generation.

  1. Life cycle assessment and evaluation of sustainable product design strategies for combined cycle power plants; Lebenszyklusanalyse und Bestimmung von Einflussfaktoren zur nachhaltigen Produktgestaltung von GuD-Kraftwerken

    Energy Technology Data Exchange (ETDEWEB)

    Parthey, Falko

    2010-03-26

    The growth of the national GDP on a worldwide level and the associated increasing demand for primary energy inevitably result in higher emissions levels. According to recent international scientific studies the energy sector (including electricity generation, industrial activities and traffic) contributes up to 83 % to the worldwide greenhouse gas emissions. Climate change and the projection of its impacts have been acknowledged also on the political level and concise measures are being considered. Since access to electricity and sustainable development are inseparable, the question arises whether and how adequate answers can be given within the coming years. Furthermore, the definite lifetime of the existing power plant fleet will result in a gap of up to 12.000 MWh in 2020, depending on the scenario. One part of the answer lies in the sustainable design of power plants. The main contribu-tion of this work is therefore the life cycle analysis of a combined cycle power plant from of a manufacturer's perspective. The visualisation of the entire product system and the re-sults of the impact assessment facilitate the determination of improvement potential. The system boundaries for this study include all relevant phases of the product life cycle (materials, manufacturing, transport, operation, service and end of life). The life cycle inventory consists of all bills of materials and energy consumption for all components and life cycle phases. The interpretation of the results of the impact assessment showed the expected significant contribution in kg CO{sub 2}e for the emission of the full load operation. Nevertheless, the results for all impact categories over the entire lifecycle are given. Various operation scenarios and configurations can now be analysed based on the elaborated modules, and can now serve as decision support already during product development. The visualisation of impacts of design decisions on the ecological footprint of the product system in

  2. Planning data book for gasification-combined-cycle plants: phased capacity additions. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, W.G.; Le, T.T.; Smith, J.T.; Sander, M.T.

    1986-01-01

    In today's environment of highly uncertain electric load growth forecasts, new generation facilities which can be constructed in small capacity increments offer the increasingly desirable characteristic of flexibility. By constructing small capacity additions, a utility can minimize its ''at risk'' capital and retain the opportunity to rapidly respond to unpredicted changes in load growth. Gasification-combined-cycle (GCC) plants, due to their modular nature, are well-suited to this sort of phased approach to capacity additions. Typically, matching load growth with small capacity additions is attended by inefficiencies and diseconomies of scale. While the modularity of GCC plants suggested that these scale penalties would be minimized, the cost and performance implications of phased GCC capacity addition required quantification. The purpose of the effort described in this report was to quantify the cost and performance impact associated with phased GCC capacity addition. Fluor Technology, Inc. carried out this quantification by maximizing the use of Texaco-based GCC design work previously performed for EPRI. More than ten utilities participated in the planning of this work, and, through their efforts, ten cases were developed for evaluation. Together, these cases provide a basis for evaluating various phasing scenarios and various GCC design options. As would be predicted, the diseconomies associated with phased GCC capacity addition are quite small. This planning data book represents a summary of the results of the Fluor work. It has been written in a form which will be most useful as a working document. The function of this report should be that of a starting point for more utility-specific evaluations.

  3. Combined Cycle Engine Large-Scale Inlet for Mode Transition Experiments: System Identification Rack Hardware Design

    Science.gov (United States)

    Thomas, Randy; Stueber, Thomas J.

    2013-01-01

    The System Identification (SysID) Rack is a real-time hardware-in-the-loop data acquisition (DAQ) and control instrument rack that was designed and built to support inlet testing in the NASA Glenn Research Center 10- by 10-Foot Supersonic Wind Tunnel. This instrument rack is used to support experiments on the Combined-Cycle Engine Large-Scale Inlet for Mode Transition Experiment (CCE? LIMX). The CCE?LIMX is a testbed for an integrated dual flow-path inlet configuration with the two flow paths in an over-and-under arrangement such that the high-speed flow path is located below the lowspeed flow path. The CCE?LIMX includes multiple actuators that are designed to redirect airflow from one flow path to the other; this action is referred to as "inlet mode transition." Multiple phases of experiments have been planned to support research that investigates inlet mode transition: inlet characterization (Phase-1) and system identification (Phase-2). The SysID Rack hardware design met the following requirements to support Phase-1 and Phase-2 experiments: safely and effectively move multiple actuators individually or synchronously; sample and save effector control and position sensor feedback signals; automate control of actuator positioning based on a mode transition schedule; sample and save pressure sensor signals; and perform DAQ and control processes operating at 2.5 KHz. This document describes the hardware components used to build the SysID Rack including their function, specifications, and system interface. Furthermore, provided in this document are a SysID Rack effectors signal list (signal flow); system identification experiment setup; illustrations indicating a typical SysID Rack experiment; and a SysID Rack performance overview for Phase-1 and Phase-2 experiments. The SysID Rack described in this document was a useful tool to meet the project objectives.

  4. Environmental Product Development Combining the Life Cycle Perspective with Chemical Hazard Information

    DEFF Research Database (Denmark)

    Askham, Cecilia

    ) are essential. Many life cycle assessments of product systems are performed without the inclusion of toxicity data and indicators. Ecodesign processes for products are often based upon just one, or very few, environmental indicators. Regulatory issues are sometimes addressed in an ad hoc fashion, often late......Concerns regarding the short- and long-term detrimental effects of chemicals on human health and ecosystems have made the minimisation of chemical hazards a vitally important issue. If sustainable development is to be achieved, environmental efficient products (and product life cycles...... in the design or redesign process. This thesis concerns marrying the life cycle perspective with chemical hazard information, in order to advance the practice of environmental product development, and hence takes further steps towards sustainable development. The need to consider the full value chain...

  5. Numerical Model of a Variable-Combined-Cycle Engine for Dual Subsonic and Supersonic Cruise

    Directory of Open Access Journals (Sweden)

    Victor Fernandez-Villace

    2013-02-01

    Full Text Available Efficient high speed propulsion requires exploiting the cooling capability of the cryogenic fuel in the propulsion cycle. This paper presents the numerical model of a combined cycle engine while in air turbo-rocket configuration. Specific models of the various heat exchanger modules and the turbomachinery elements were developed to represent the physical behavior at off-design operation. The dynamic nature of the model allows the introduction of the engine control logic that limits the operation of certain subcomponents and extends the overall engine operational envelope. The specific impulse and uninstalled thrust are detailed while flying a determined trajectory between Mach 2.5 and 5 for varying throttling levels throughout the operational envelope.

  6. Thermal-CFD Analysis of Combined Solar-Nuclear Cycle Systems.

    Energy Technology Data Exchange (ETDEWEB)

    Fathi, Nima [Univ. of New Mexico, Albuquerque, NM (United States); McDaniel, Patrick [Univ. of New Mexico, Albuquerque, NM (United States); Vorobieff, Peter [Univ. of New Mexico, Albuquerque, NM (United States); de Oliveira, Cassiano [Univ. of New Mexico, Albuquerque, NM (United States); Rodriguez, Salvador B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Aleyasin, Seyed Sobhan [Univ. of Manitoba (Canada)

    2015-09-01

    The aim of this paper is evaluating the efficiency of a novel combined solar-nuclear cycle. CFD-Thermal analysis is performed to apply the available surplus heat from the nuclear cycle and measure the available kinetic energy of air for the turbine of a solar chimney power plant system (SCPPS). The presented idea helps to decrease the thermal pollution and handle the water shortage supply for water plant by replacing the cooling tower by solar chimney power plant to get the surplus heat from the available warm air in the secondary loop of the reactor. By applying this idea to a typical 1000 MW nuclear power plant with a 0.33 thermal efficiency, we can increase it to 0.39.

  7. Modern combined cycle power plant utilizing the GT11N2

    International Nuclear Information System (INIS)

    Goodwin, J.C.

    1992-01-01

    The requirement imposed on modern power plants are increasingly demanding. The limits of: efficiency; environmental sensitivity; reliability and availability; are constantly being pushed. Today's state of the art combined cycle power plants are positioned well to meet these challenges. This paper reports that these objectives can be achieved through the selection of the proper gas turbine generator in an optimized cycle concept. A balanced approach to the plant design is required. It must not sacrifice any one of these requirements, in order to achieve the others. They achieve their fullest potential when firing a clean fuel, natural gas. However, fuel oil, both light (No. 2) and heavy (No. 6), can be utilized but some efficiency and environmental impact will have to be sacrificed

  8. Lower central combined cycle project: Conceptual design. Volume 3. Export trade information

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-08-01

    This study, conducted by Black & Veatch International, was funded by the U.S. Trade and Development Agency. The report addresses various technical, environmental, and economic aspects of developing eight 600 MW blocks of combined cycle electric generating facilities at a site located northeast of Ratchaburi. The study contains a detailed environmental assessment, as well as fueling options and cost estimates. The report consists of 5 volumes, a Feasibility Study report and four Conceptual Design studies. This volume is the Conceptual Design-Volume 3 and is divided as follows: (1) Auxiliary Power Supply; (2) Buildings and Structures; (3) Compressed Air; (4) Control; (5) Cycle Heat Rejection; (6) Electrical; (7) Equipment Cooling; (8) Feedwater; (9) Fire Protection; (10) Fual Gas.

  9. Evaluation of alternatives of exothermic methanization cycle for combined electricity and heat generation

    International Nuclear Information System (INIS)

    Balajka, J.; Princova, H.

    1987-01-01

    The possibilities are discussed of using the ADAM-EVA system for remote heat supply from nuclear heat sources to district heating systems. Attention is devoted to the use of the exothermal methanization process (ADAM station) for the combined power and heat production, this making use of the existing hot water power distribution network. The basic parameter for the evaluation of the over-all efficiency of the combined power and heat production is the maximum methanization cycle temperature which depends on the life of the methanization catalyst. Upon temperature drop below 550 degC, the conversion process can only be secured by means of two-stage methanization, which leads to a simplification of the cycle and a reduction in investment cost. At a temperature lower than 500 degC, combined power and heat production cannot be implemented. On the contrary, a considerable amount of electric power supplied from outside the system would be needed for compression work. (Z.M.)

  10. Evaluation method for regional water cycle health based on nature-society water cycle theory

    Science.gov (United States)

    Zhang, Shanghong; Fan, Weiwei; Yi, Yujun; Zhao, Yong; Liu, Jiahong

    2017-08-01

    Regional water cycles increasingly reflect the dual influences of natural and social processes, and are affected by global climate change and expanding human activities. Understanding how to maintain a healthy state of the water cycle has become an important proposition for sustainable development of human society. In this paper, natural-social attributes of the water cycle are synthesized and 19 evaluation indices are selected from four dimensions, i.e., water-based ecosystem integrity, water quality, water resource abundance and water resource use. A hierarchical water-cycle health evaluation system is established. An analytic hierarchy process is used to set the weight of the criteria layer and index layer, and the health threshold for each index is defined. Finally, a water-cycle health composite-index assessment model and fuzzy recognition model are constructed based on the comprehensive index method and fuzzy mathematics theory. The model is used to evaluate the state of health of the water cycle in Beijing during 2010-2014 and in the planning year (late 2014), considering the transfer of 1 billion m3 of water by the South-to-North Water Diversion Project (SNWDP). The results show health scores for Beijing of 2.87, 3.10, 3.38, 3.11 and 3.02 during 2010-2014. The results of fuzzy recognition show that the sub-healthy grade accounted for 54%, 49%, 61% and 49% of the total score, and all years had a sub-healthy state. Results of the criteria layer analysis show that water ecosystem function, water quality and water use were all at the sub-healthy level and that water abundance was at the lowest, or sick, level. With the water transfer from the SNWDP, the health score of the water cycle in Beijing reached 4.04. The healthy grade accounted for 60% of the total score, and the water cycle system was generally in a healthy state. Beijing's water cycle health level is expected to further improve with increasing water diversion from the SNWDP and industrial

  11. Study on effective parameter of the triple-pressure reheat combined cycle performance

    Directory of Open Access Journals (Sweden)

    Ibrahim Thamir K.

    2013-01-01

    Full Text Available The thermodynamic analyses of the triple-pressure reheat combined cycle gas turbines with duct burner are presented and discussed in this paper. The overall performance of a combined cycle gas turbine power plant is influenced by the ambient temperature, compression ratio and turbine inlet temperature. These parameters affect the overall thermal efficiency, power output and the heat-rate. In this study a thermodynamic model was development on an existing actual combined cycle gas turbine (CCGT (In this case study, an effort has been made to enhance the performance of the CCGT through a parametric study using a thermodynamic analysis. The effect of ambient temperature and operation parameter, including compression ratio and turbine inlet temperature, on the overall performance of CCGT are investigated. The code of the performance model for CCGT power plant was developed utilizing the THERMOFLEX software. The simulating results show that the total power output and overall efficiency of a CCGT decrease with increase the ambient temperature because increase the consumption power in the air compressor of a GT. The totals power of a CCGT decreases with increase the compression rate, while the overall efficiency of a CCGT increases with increase the compression ratio to 21, after that the overall efficiency will go down. Far there more the turbine inlet temperature increases the both total power and overall efficiency increase, so the turbine inlet temperature has a strong effect on the overall performance of CCGT power plant. Also the simulation model give a good result compared with MARAFIQ CCGT power plant. With these variables, the turbine inlet temperature causes the greatest overall performance variation.

  12. Evaluating the hydrological consistency of satellite based water cycle components

    KAUST Repository

    Lopez Valencia, Oliver Miguel

    2016-06-15

    Advances in multi-satellite based observations of the earth system have provided the capacity to retrieve information across a wide-range of land surface hydrological components and provided an opportunity to characterize terrestrial processes from a completely new perspective. Given the spatial advantage that space-based observations offer, several regional-to-global scale products have been developed, offering insights into the multi-scale behaviour and variability of hydrological states and fluxes. However, one of the key challenges in the use of satellite-based products is characterizing the degree to which they provide realistic and representative estimates of the underlying retrieval: that is, how accurate are the hydrological components derived from satellite observations? The challenge is intrinsically linked to issues of scale, since the availability of high-quality in-situ data is limited, and even where it does exist, is generally not commensurate to the resolution of the satellite observation. Basin-scale studies have shown considerable variability in achieving water budget closure with any degree of accuracy using satellite estimates of the water cycle. In order to assess the suitability of this type of approach for evaluating hydrological observations, it makes sense to first test it over environments with restricted hydrological inputs, before applying it to more hydrological complex basins. Here we explore the concept of hydrological consistency, i.e. the physical considerations that the water budget impose on the hydrologic fluxes and states to be temporally and spatially linked, to evaluate the reproduction of a set of large-scale evaporation (E) products by using a combination of satellite rainfall (P) and Gravity Recovery and Climate Experiment (GRACE) observations of storage change, focusing on arid and semi-arid environments, where the hydrological flows can be more realistically described. Our results indicate no persistent hydrological

  13. Combined cycle power plant with indirect dry cooling tower forecasting using artificial neural network

    Directory of Open Access Journals (Sweden)

    Asad Dehghani Samani

    2017-07-01

    Full Text Available Application of Artificial Neural Network (ANN in modeling of combined cycle power plant (CCPP with dry cooling tower (Heller tower has been investigated in this paper. Prediction of power plant output (megawatt under different working conditions was made using multi-layer feed-forward ANN and training was performed with operational data using back-propagation. Two ANN network was constructed for the steam turbine (ST and the main cooling system(MCS. Results indicate that the ANN model is effective in predicting the power plant output with good accuracy.

  14. Response Surface Modeling of Combined-Cycle Propulsion Components using Computational Fluid Dynamics

    Science.gov (United States)

    Steffen, C. J., Jr.

    2002-01-01

    Three examples of response surface modeling with CFD are presented for combined cycle propulsion components. The examples include a mixed-compression-inlet during hypersonic flight, a hydrogen-fueled scramjet combustor during hypersonic flight, and a ducted-rocket nozzle during all-rocket flight. Three different experimental strategies were examined, including full factorial, fractionated central-composite, and D-optimal with embedded Plackett-Burman designs. The response variables have been confined to integral data extracted from multidimensional CFD results. Careful attention to uncertainty assessment and modeling bias has been addressed. The importance of automating experimental setup and effectively communicating statistical results are emphasized.

  15. Combined cycle power plants with an integrated HTW-brown gasification

    International Nuclear Information System (INIS)

    Wischnewski, R.; Schippers, K.

    1993-01-01

    Despite the fact that there is still a potential to improve the efficiency of classic brown coal power plants by various measures from 36% to approx. 40-41%, the essential big increase of the efficiency to values of approx. 46% can only be achieved by the transition to combined gas and steam turbine processes. This means for the solid fuel brown coal that a gasification is integrated into the power plant process. The combined cycle power plant with an integrated brown coal gasification represents this new power plant concept. The applied High Temperature Winkler method (HTW-method) is an advancement of the Winkler method that works at environmental pressure and was developed by the Rheinbraun AG. (orig./DG) [de

  16. Gasification/combined-cycle power generation: environmental assessment of alternative systems

    Energy Technology Data Exchange (ETDEWEB)

    1978-11-01

    This report provides a basis for the comparative assessment of the potential performance capability, technological development, and economic and environmental impact associated with the operation of integrated low-Btu coal-gasification/combined-cycle power systems. Characterization of the integrated power system in terms of fuel processing, power production, and auxiliary systems is followed up with comparisons of alternative integrated-plant-design/fuel combinations with reference to the conventional coal-fired power plant, taking into account both economic and environmental factors. The report includes an assessment of the effects of recent regulatory changes on the prospects for integrated power systems and establishes a timetable for the probable commercial development of such systems by the utilities.

  17. Complex technical and economic studies of combined-cycle units with flow gasifiers

    Science.gov (United States)

    Nakoryakov, V. E.; Nozdrenko, G. V.; Shchinnikov, P. A.; Borush, O. V.; Kuz'min, A. G.

    2010-12-01

    The method for determining the technical and economical indices of combined-cycle power plants (CCPPs) operating on coal with a low-charged steam generator and with a flow gasifier in combined production of electricity and heat, synthesis gas and hydrogen is considered. The results of analysis are presented and it is shown that such CCPPs have a higher technical and economical efficiency as compared to cogeneration plants (CPs) operating on pulverized coal and reconstructed with a gas-turbine topping. The material of this article is prepared in the framework of the Federal Targeted Program "Scientific and Scientific-Pedagogical Specialists of Innovative Russia for 2009-2013," application 1.2.2, the program "Research Works on Production of Fuels and Power from Organic Raw Materials."

  18. The combination of an Environmental Management System and Life Cycle Assessment at the territorial level

    International Nuclear Information System (INIS)

    Mazzi, Anna; Toniolo, Sara; Catto, Stella; De Lorenzi, Valentina; Scipioni, Antonio

    2017-01-01

    A framework to include a Life Cycle Assessment in the significance evaluation of the environmental aspects of an Environmental Management System has been studied for some industrial sectors, but there is a literature gap at the territorial level, where the indirect impact assessment is crucial. To overcome this criticality, our research proposes the Life Cycle Assessment as a framework to assess environmental aspects of public administration within an Environmental Management System applied at the territorial level. This research is structured in two parts: the design of a new methodological framework and the pilot application for an Italian municipality. The methodological framework designed supports Initial Environmental Analysis at the territorial level thanks to the results derived from the impact assessment phase. The pilot application in an Italian municipality EMAS registered demonstrates the applicability of the framework and its effectiveness in evaluating the environmental impact assessment for direct and indirect aspects. Through the discussion of the results, we underline the growing knowledge derived by this research in terms of the reproducibility and consistency of the criteria to define the significance of the direct and indirect environmental aspects for a local public administration. - Highlights: • The combination between Environmental Management System and LCA is studied. • A methodological framework is elaborated and tested at the territorial level. • Life Cycle Impact Assessment supports the evaluation of aspects significance. • The framework assures consistency of evaluation criteria on the studied territory.

  19. Inspection of a prototype of rocket based combined cycle engine

    Science.gov (United States)

    1998-01-01

    The Direct Gain Solar Thermal Engine was designed with no moving parts. The concept of Solar Thermal Propulsion Research uses focused solar energy from an inflatable concentrator (a giant magnifying glass) to heat a propellant (hydrogen) and allows thermal expansion through the nozzle for low thrust without chemical combustion. Energy limitations and propellant weight associated with traditional combustion engines are non-existant with this concept. The Direct Gain Solar Thermal Engine would be used for moving from a lower orbit to an upper synchronous orbit.

  20. Life-cycle performance of structures: combining expert judgment and results of inspection

    OpenAIRE

    Neves, Luis Canhoto

    2008-01-01

    Life-Cycle Civil Engineering – Biondini & Frangopol Current bridge management systems base decisions on the results of visual inspections. These systems consider visual inspection results as accurate and disregard any further information available. In the present study, the result of each inspection is considered as a random variable, dependent of a wide range of factors, that can be integrated with other sources of information, including expert judgment and results of other inspections...

  1. Performance Analysis of Solar Combined Ejector-Vapor Compression Cycle Using Environmental Friendly Refrigerants

    Directory of Open Access Journals (Sweden)

    A. B. Kasaeian

    2013-04-01

    Full Text Available In this study, a new model of a solar combined ejector-vapor compression refrigeration system has been considered. The system is equipped with an internal heat exchanger to enhance the performance of the cycle. The effects of working fluid and operating conditions on the system performance including COP, entrainment ratio (ω, compression ratio (rp and exergy efficiency were investigated. Some working fluids suggested are: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e and R1234ze(z. The results show that R114 and R1234ze(e yield the highest COP and exergy efficiency followed by R123, R245fa, R365mfc, R141b, R152a and R600a. It is noticed that the COP value of the new solar ejector-vapor compression refrigeration cycle is higher than that of the conventional ejector cycle with R1234ze(e for all operating conditions. This paper also demonstrates that R1234ze(e will be a suitable refrigerant in the solar combined ejector-vapor compression refrigeration system, due to its environmental friendly properties and better performance. ABSTRAK: Kajian ini menganalisa model baru sistem penyejukan mampatan gabungan ejektor-wap solar.Sistem ini dilengkapi dengan penukar haba dalaman untuk meningkatkan prestasi kitaran.Kesan bendalir bekerja dan keadaan operasi pada prestasi sistem termasuk COP, nisbah pemerangkapan (ω, nisbah mampatan (rp dan kecekapan eksergi telah disiasat.Beberapa bendalir bekerja yang dicadangkan adalah: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e dan R1234ze(z.Hasil kajian menunjukkan R114 dan R1234ze(e menghasilkan COP dan kecekapan eksergi tertinggi diikuti oleh R123, R245fa, R365mfc, R141b, R152a dan R600a.Didapati nilai COP kitaran penyejukan mampatan bagi ejektor-wap solar baru adalah lebih tinggi daripada kitaran ejektor konvensional dengan R1234ze(e bagi semua keadaan operasi.Kertas kerja ini juga menunjukkan bahawa R1234ze(e boleh menjadi penyejuk yang sesuai dalam sistem penyejukan mampatan gabungan ejektor

  2. Municipal solid wastes incineration with combined cycle: a case study from Sao Paulo

    Energy Technology Data Exchange (ETDEWEB)

    Cerda Balcazar, Juan Galvarino; Dias, Rubens Alves; Balestieri, Jose Antonio Perrella [Universidade Estadual Paulista (UNESP), Guaratingueta, SP (Brazil)], E-mails: pos09007@feg.unesp.br, rubdias@feg.unesp.br

    2010-07-01

    Large urban centers have a huge demand for electricity, for the needs of its residents, and a growing problem of management of solid waste generated by it, that becomes an public administrative and great social problem. The correct disposal of solid waste generated by large urban centers is now one of the most complex engineering problems involving logistics, safety, environment, energy spent among other tools for sound management of municipal solid waste (MSW). This study was carried out a study of the use of incinerators and residue derived fuel and MSW with combined cycles, with the aim of producing thermal and mechanical energy (this later becomes electrical energy) and solid waste treatment in Sao Paulo. We used existing models and real plants in the European Union in this case, with the aim of making it the most viable and compatible with the current context of energy planning and resource today. A technical and economic feasibility study for a plant of this nature, using the scheme, is presented. It is expected a good attractiveness of using incinerators combined-cycle, due to its high efficiency and its ability to thermoelectric generation. (author)

  3. Prospective gas turbine and combined-cycle units for power engineering (a Review)

    Science.gov (United States)

    Ol'khovskii, G. G.

    2013-02-01

    The modern state of technology for making gas turbines around the world and heat-recovery combined-cycle units constructed on their basis are considered. The progress achieved in this field by Siemens, Mitsubishi, General Electric, and Alstom is analyzed, and the objectives these companies set forth for themselves for the near and more distant future are discussed. The 375-MW gas turbine unit with an efficiency of 40% produced by Siemens, which is presently the largest one, is subjected to a detailed analysis. The main specific features of this turbine are that the gas turbine unit's hot-path components have purely air cooling, due to which the installation has enhanced maneuverability. The single-shaft combined-cycle plant constructed on the basis of this turbine has a capacity of 570 MW and efficiency higher than 60%. Programs adopted by different companies for development of new-generation gas turbine units firing synthesis gas and fitted with low-emission combustion chambers and new cooling systems are considered. Concepts of rotor blades for new gas turbine units with improved thermal barrier coatings and composite blades different parts of which are made of materials selected in accordance with the conditions of their operation are discussed.

  4. Optimization of controlled processes in combined-cycle plant (new developments and researches)

    Science.gov (United States)

    Tverskoy, Yu S.; Muravev, I. K.

    2017-11-01

    All modern complex technical systems, including power units of TPP and nuclear power plants, work in the system-forming structure of multifunctional APCS. The development of the modern APCS mathematical support allows bringing the automation degree to the solution of complex optimization problems of equipment heat-mass-exchange processes in real time. The difficulty of efficient management of a binary power unit is related to the need to solve jointly at least three problems. The first problem is related to the physical issues of combined-cycle technologies. The second problem is determined by the criticality of the CCGT operation to changes in the regime and climatic factors. The third problem is related to a precise description of a vector of controlled coordinates of a complex technological object. To obtain a joint solution of this complex of interconnected problems, the methodology of generalized thermodynamic analysis, methods of the theory of automatic control and mathematical modeling are used. In the present report, results of new developments and studies are shown. These results allow improving the principles of process control and the automatic control systems structural synthesis of power units with combined-cycle plants that provide attainable technical and economic efficiency and operational reliability of equipment.

  5. Effective energy management by combining gas turbine cycles and forward osmosis desalination process

    International Nuclear Information System (INIS)

    Park, Min Young; Shin, Serin; Kim, Eung Soo

    2015-01-01

    Highlights: • Innovative gas turbine system and FO integrated system was proposed. • The feasibility of the integrated system was analyzed thermodynamically. • GOR of the FO–gas turbine system is 17% higher than those of MED and MSF. • Waste heat utilization of the suggested system is 85.7%. • Water production capacity of the suggested system is 3.5 times higher than the MSF–gas turbine system. - Abstract: In the recent years, attempts to improve the thermal efficiency of the gas turbine cycles have been made. In order to enhance the energy management of the gas turbine cycle, a new integration concept has been proposed; integration of gas turbine cycle and forward osmosis desalination process. The combination of the gas turbine cycle and the forward osmosis (FO) desalination process basically implies the coupling of the waste heat from the gas turbine cycle to the draw solute recovery system in the FO process which is the most energy consuming part of the whole FO process. By doing this, a strong system that is capable of producing water and electricity with very little waste heat can be achieved. The feasibility of this newly proposed system was analyzed using UNISIM program and the OLI property package. For the analysis, the thermolytic draw solutes which has been suggested by other research groups have been selected and studied. Sensitivity analysis was conducted on the integration system in order to understand and identify the key parameters of the integrated system. And the integrated system was further evaluated by comparing the gain output ratio (GOR) values with the conventional desalination technologies such as multi stage flash (MSF) and multi effect distillation (MED). The suggested integrated system was calculated to have a GOR of 14.8, while the MSF and MED when integrated to the gas turbine cycle showed GOR value of 12. It should also be noted that the energy utilization of the suggested integrated system is significantly higher by 27

  6. Novel Chromosome Organization Pattern inActinomycetales-Overlapping Replication Cycles Combined with Diploidy.

    Science.gov (United States)

    Böhm, Kati; Meyer, Fabian; Rhomberg, Agata; Kalinowski, Jörn; Donovan, Catriona; Bramkamp, Marc

    2017-06-06

    Bacteria regulate chromosome replication and segregation tightly with cell division to ensure faithful segregation of DNA to daughter generations. The underlying mechanisms have been addressed in several model species. It became apparent that bacteria have evolved quite different strategies to regulate DNA segregation and chromosomal organization. We have investigated here how the actinobacterium Corynebacterium glutamicum organizes chromosome segregation and DNA replication. Unexpectedly, we found that C. glutamicum cells are at least diploid under all of the conditions tested and that these organisms have overlapping C periods during replication, with both origins initiating replication simultaneously. On the basis of experimental data, we propose growth rate-dependent cell cycle models for C. glutamicum IMPORTANCE Bacterial cell cycles are known for few model organisms and can vary significantly between species. Here, we studied the cell cycle of Corynebacterium glutamicum , an emerging cell biological model organism for mycolic acid-containing bacteria, including mycobacteria. Our data suggest that C. glutamicum carries two pole-attached chromosomes that replicate with overlapping C periods, thus initiating a new round of DNA replication before the previous one is terminated. The newly replicated origins segregate to midcell positions, where cell division occurs between the two new origins. Even after long starvation or under extremely slow-growth conditions, C. glutamicum cells are at least diploid, likely as an adaptation to environmental stress that may cause DNA damage. The cell cycle of C. glutamicum combines features of slow-growing organisms, such as polar origin localization, and fast-growing organisms, such as overlapping C periods. Copyright © 2017 Böhm et al.

  7. Economics analysis of fuel cycle cost of fusion–fission hybrid reactors based on different fuel cycle strategies

    Energy Technology Data Exchange (ETDEWEB)

    Zu, Tiejun, E-mail: tiejun@mail.xjtu.edu.cn; Wu, Hongchun; Zheng, Youqi; Cao, Liangzhi

    2015-01-15

    Highlights: • Economics analysis of fuel cycle cost of FFHRs is carried out. • The mass flows of different fuel cycle strategies are established based on the equilibrium fuel cycle model. • The levelized fuel cycle costs of different fuel cycle strategies are calculated, and compared with current once-through fuel cycle. - Abstract: The economics analysis of fuel cycle cost of fusion–fission hybrid reactors has been performed to compare four fuel cycle strategies: light water cooled blanket burning natural uranium (Strategy A) or spent nuclear fuel (Strategy B), sodium cooled blanket burning transuranics (Strategy C) or minor actinides (Strategy D). The levelized fuel cycle costs (LFCC) which does not include the capital cost, operation and maintenance cost have been calculated based on the equilibrium mass flows. The current once-through (OT) cycle strategy has also been analyzed to serve as the reference fuel cycle for comparisons. It is found that Strategy A and Strategy B have lower LFCCs than OT cycle; although the LFCC of Strategy C is higher than that of OT cycle when the uranium price is at its nominal value, it would become comparable to that of OT cycle when the uranium price reaches its historical peak value level; Strategy D shows the highest LFCC, because it needs to reprocess huge mass of spent nuclear fuel; LFCC is sensitive to the discharge burnup of the nuclear fuel.

  8. Economic competitiveness of small modular reactors versus coal and combined cycle plants

    International Nuclear Information System (INIS)

    Alonso, Gustavo; Bilbao, Sama; Valle, Edmundo del

    2016-01-01

    Small modular reactors (SMRs) may be an option to cover the electricity needs of isolated regions, distributed generation grids and countries with small electrical grids. Previous analyses show that the overnight capital cost for SMRs is between 4500 US$/kW and 5350 US$/kW, which is between a 6% and a 26% higher than the average cost of a current large nuclear reactor. This study analyzes the economic competitiveness of small modular reactors against thermal plants using coal and natural gas combined cycle plants. To assess the economic competitiveness of SMRs, three overnight capital costs are considered 4500 US$/kW, 5000 US$/kW and 5350 US$/kW along with three discount rates for each overnight cost considered, these are 3, 7, and 10%. To compare with natural gas combined cycle (CC) units, four different gas prices are considered, these are 4.74 US$/GJ (5 US$/mmBTU), 9.48 US$/GJ (10 US$/mmBTU), 14.22 US$/GJ (15 US$/mmBTU), and 18.96 US$/GJ (20 US$/mmBTU). To compare against coal, two different coal prices are considered 80 and 120 US$/ton of coal. The carbon tax considered, for both CC and coal, is 30 US$/ton CO 2 . The results show what scenarios make SMRs competitive against coal and/or combined cycle plants. In addition, because the price of electricity is a key component to guarantee the feasibility of a new project, this analysis calculates the price of electricity for the economically viable deployment of SMRs in all the above scenarios. In particular, this study shows that a minimum price of electricity of 175 US$/MWh is needed to guarantee the feasibility of a new SMR, if its overnight capital cost is 5350 US$/kWe and the discount rate is 10%. Another result is that when the price of electricity is around 100 US$/MWh then the discount rate must be around 7% or less to provide appropriate financial conditions to make SMRs economically feasible. - Highlights: • Small modular reactor (SMR) are economically assessed. • SMR are compared against gas and coal

  9. Thermodynamic performance analysis of a combined power cycle using low grade heat source and LNG cold energy

    International Nuclear Information System (INIS)

    Kim, Kyoung Hoon; Kim, Kyung Chun

    2014-01-01

    Thermodynamic analysis of a combined cycle using a low grade heat source and LNG cold energy was carried out. The combined cycle consisted of an ammonia–water Rankine cycle with and without regeneration and a LNG Rankine cycle. A parametric study was conducted to examine the effects of the key parameters, such as ammonia mass fraction, turbine inlet pressure, condensation temperature. The effects of the ammonia mass fraction on the temperature distributions of the hot and cold streams in heat exchangers were also investigated. The characteristic diagram of the exergy efficiency and heat transfer capability was proposed to consider the system performance and expenditure of the heat exchangers simultaneously. The simulation showed that the system performance is influenced significantly by the parameters with the ammonia mass fraction having largest effect. The net work output of the ammonia–water cycle may have a peak value or increase monotonically with increasing ammonia mass fraction, which depends on turbine inlet pressure or condensation temperature. The exergy efficiency may decrease or increase or have a peak value with turbine inlet pressure depending on the ammonia mass fraction. - Highlights: • Thermodynamic analysis was performed for a combined cycle utilizing LNG cold energy. • Ammonia–water Rankine cycle and LNG Rankine cycle was combined. • A parametric study was conducted to examine the effects of the key parameters. • Characteristics of the exergy efficiency and heat transfer capability were proposed. • The system performance was influenced significantly by the ammonia mass fraction

  10. Gasification and combined cycles: Present situation and future prospects; Gassificazione e ciclo combinato: Situazione attuale e prospettive

    Energy Technology Data Exchange (ETDEWEB)

    Brustia, G.F.; Bressan, L.; Domenichini, R.

    1992-12-31

    The gasification of coal and/or residual fuels from refineries together with the use of combined cycle power generation systems represents a technically and economically feasible method for the conversion of poor quality fossil fuels into electric power. The conversion is accomplished with maximum respect for the severest environmental normatives. In addition, foreseen technical improvements for components and plant systems are expected to heighten the marketing potential of gasification/combined cycle power plants. After Italy`s moratorium on nuclear energy, the passing eras of conventional fossil fuel and then combined cycle power plants, the need for highly competitive industrial production technologies and the urgency of nation-wide energy conservation appear to be ushering in the new era of gasification with combined cycles.

  11. Conversion of coal-fired power plants to cogeneration and combined-cycle thermal and economic effectiveness

    CERN Document Server

    Bartnik, Ryszard

    2014-01-01

    This book covers methodology, calculation procedures and tools to support enterprise planning for adapting power stations to cogeneration and combined-cycle forms. It examines the optimum selection of the structure of heat exchangers in a 370 MW power block.

  12. The combined effect of cycling cadence and crank resistance on hamstrings and quadriceps muscle activities during cycling.

    Science.gov (United States)

    Katona, P; Pilissy, T; Tihanyi, A; Laczkó, József

    2014-12-01

    The effect of cycling cadence and crank resistance on the activity of hamstrings and quadriceps muscles was investigated during cycling movements of able-bodied subjects on a stationary bike with slow and fast speed against different resistance conditions. The ratio of average EMG amplitudes obtained in the two speed conditions (fast/slow) was computed in each resistance condition. This ratio is higher for both muscles if cycling against higher resistance. This shows that in higher resistance condition muscle activities are not only increased but the change of muscle activities with respect to cadence change varied according to resistance condition. Average EMG amplitudes increased at a higher rate with respect to change of cadence when cycling was performed in higher resistance condition. Besides, when cycling faster, hamstrings activity increased generally at a higher rate than that of quadriceps. The correlation between cadence and EMG amplitudes were also investigated. Considering hamstrings, this correlation was low and decreased as resistance increased. The correlation between the time required to drive one cycle and EMG amplitude is negative but in absolute value it is larger than the correlation of cadence and EMG amplitude.

  13. Performance analysis of a combined organic Rankine cycle and vapor compression cycle for power and refrigeration cogeneration

    International Nuclear Information System (INIS)

    Kim, Kyoung Hoon; Perez-Blanco, Horacio

    2015-01-01

    A thermodynamic analysis of cogeneration of power and refrigeration activated by low-grade sensible energy is presented in this work. An organic Rankine cycle (ORC) for power production and a vapor compression cycle (VCC) for refrigeration using the same working fluid are linked in the analysis, including the limiting case of cold production without net electricity production. We investigate the effects of key parameters on system performance such as net power production, refrigeration, and thermal and exergy efficiencies. Characteristic indexes proportional to the cost of heat exchangers or of turbines, such as total number of transfer units (NTU tot ), size parameter (SP) and isentropic volumetric flow ratio (VFR) are also examined. Three important system parameters are selected, namely turbine inlet temperature, turbine inlet pressure, and the flow division ratio. The analysis is conducted for several different working fluids. For a few special cases, isobutane is used for a sensitivity analysis due to its relatively high efficiencies. Our results show that the system has the potential to effectively use low grade thermal sources. System performance depends both on the adopted parameters and working fluid. - Highlights: • Waste heat utilization can reduce emissions of carbon dioxide. • The ORC/VCC cycle can deliver power and/or refrigeration using waste heat. • Efficiencies and size parameters are used for cycle evaluation. • The cycle performance is studied for eight suitable refrigerants. Isobutane is used for a sensitivity analysis. • The work shows that the isobutene cycle is quite promising.

  14. Continuous or extended cycle vs. cyclic use of combined hormonal contraceptives for contraception.

    Science.gov (United States)

    Edelman, Alison; Micks, Elizabeth; Gallo, Maria F; Jensen, Jeffrey T; Grimes, David A

    2014-07-29

    The avoidance of menstruation through continuous or extended (greater than 28 days) administration of combination hormonal contraceptives (CHCs) has gained legitimacy through its use in treating endometriosis, dysmenorrhea, and menstruation-associated symptoms. Avoidance of menstruation through extended or continuous use of CHCs for reasons of personal preference may have additional advantages to women, including improved compliance, greater satisfaction, fewer menstrual symptoms, and less menstruation-related absenteeism from work or school. To determine the differences between continuous or extended-cycle CHCs (pills, patch, ring) in regimens of greater than 28 days of active hormone compared with traditional cyclic dosing (21 days of active hormone and 7 days of placebo, or 24 days of active hormones and 4 days of placebo). Our hypothesis was that continuous or extended-cycle CHCs have equivalent efficacy and safety but improved bleeding profiles, amenorrhea rates, adherence, continuation, participant satisfaction, and menstrual symptoms compared with standard cyclic CHCs. We searched computerized databases (Cochrane Central Register of Controlled Trials, PUBMED, EMBASE, POPLINE, LILACS) for trials using continuous or extended CHCs (oral contraceptives, contraceptive ring and patch) during the years 1966 to 2013. We also searched the references in review articles and publications identified for inclusion in the protocol. Investigators were contacted regarding additional references. All randomized controlled trials in any language comparing continuous or extended-cycle (greater than 28 days of active hormones) versus traditional cyclic administration (21 days of active hormones and 7 days of placebo, or 24 days of active hormones and 4 days of placebo) of CHCs for contraception. Titles and abstracts identified from the literature searches were assessed for potential inclusion. Data were extracted onto data collection forms and then entered into RevMan 5. Peto

  15. Effect of Gas Turbine Exhaust Temperature, Stack Temperature and Ambient Temperature on Overall Efficiency of Combine Cycle Power Plant

    OpenAIRE

    M.N.Khan; K.P.Tyagi

    2010-01-01

    The gas turbine exhaust temperature, stack temperature and ambient temperature play a very important role during the predication of the performance of combine cycle power plant. This paper covers parametric analysis of effects of gas turbine exhaust temperature, stack temperature and ambient temperature on the overall efficiency of combine cycle power plant keeping the gas turbine efficiency as well as steam turbine efficiency constant. The results shows that out of three variables i.e. turbi...

  16. Advanced modeling and simulation of integrated gasification combined cycle power plants with CO2-capture

    International Nuclear Information System (INIS)

    Rieger, Mathias

    2014-01-01

    The objective of this thesis is to provide an extensive description of the correlations in some of the most crucial sub-processes for hard coal fired IGCC with carbon capture (CC-IGCC). For this purpose, process simulation models are developed for four industrial gasification processes, the CO-shift cycle, the acid gas removal unit, the sulfur recovery process, the gas turbine, the water-/steam cycle and the air separation unit (ASU). Process simulations clarify the influence of certain boundary conditions on plant operation, performance and economics. Based on that, a comparative benchmark of CC-IGCC concepts is conducted. Furthermore, the influence of integration between the gas turbine and the ASU is analyzed in detail. The generated findings are used to develop an advanced plant configuration with improved economics. Nevertheless, IGCC power plants with carbon capture are not found to be an economically efficient power generation technology at present day boundary conditions.

  17. Real-world experience of women using extended-cycle vs monthly-cycle combined oral contraception in the United States: the National Health and Wellness Survey.

    Science.gov (United States)

    Nappi, Rossella E; Lete, Iñaki; Lee, Lulu K; Flores, Natalia M; Micheletti, Marie-Christine; Tang, Boxiong

    2018-01-18

    The real-world experience of women receiving extended-cycle combined oral contraception (COC) versus monthly-cycle COC has not been reported. Data were from the United States 2013 National Health and Wellness Survey. Eligible women (18-50 years old, premenopausal, without hysterectomy) currently using extended-cycle COC (3 months between periods) were compared with women using monthly-cycle COC. Treatment satisfaction (1 "extremely dissatisfied" to 7 "extremely satisfied"), adherence (8-item Morisky Medication Adherence Scale © ), menstrual cycle-related symptoms, health-related quality of life (HRQOL) and health state utilities (Medical Outcomes Short Form Survey-36v2®), depression (9-item Patient Health Questionnaire), sleep difficulties, Work Productivity and Activity Impairment-General Health, and healthcare resource use were assessed using one-way analyses of variance, chi-square tests, and generalized linear models (adjusted for covariates). Participants included 260 (6.7%) women using extended-cycle and 3616 (93.3%) using monthly-cycle COC. Women using extended-cycle COC reported significantly higher treatment satisfaction (P = 0.001) and adherence (P = 0.04) and reduced heavy menstrual bleeding (P = 0.029). A non-significant tendency toward reduced menstrual pain (39.5% versus 47.3%) and menstrual cycle-related symptoms (40.0% versus 48.7%) was found in women using extended-cycle versus monthly-cycle COC. Significantly more women using extended-cycle COC reported health-related diagnoses, indicating preferential prescription for extended-cycle COC among women reporting more health problems. Consistent with this poorer health, more women using extended-cycle COC reported fatigue, headache, and activity impairment (P values < 0.05). There were no other significant differences between groups. This real-world observational study supports extended-cycle COC as a valuable treatment option with high satisfaction, high adherence, and reduced

  18. Analysis of Combined Cycle Power Plants with Chemical Looping Reforming of Natural Gas and Pre-Combustion CO2 Capture

    Directory of Open Access Journals (Sweden)

    Shareq Mohd Nazir

    2018-01-01

    Full Text Available In this paper, a gas-fired combined cycle power plant subjected to a pre-combustion CO2 capture method has been analysed under different design conditions and different heat integration options. The power plant configuration includes the chemical looping reforming (CLR of natural gas (NG, water gas shift (WGS process, CO2 capture and compression, and a hydrogen fuelled combined cycle to produce power. The process is denoted as a CLR-CC process. One of the main parameters that affects the performance of the process is the pressure for the CLR. The process is analysed at different design pressures for the CLR, i.e., 5, 10, 15, 18, 25 and 30 bar. It is observed that the net electrical efficiency increases with an increase in the design pressure in the CLR. Secondly, the type of steam generated from the cooling of process streams also effects the net electrical efficiency of the process. Out of the five different cases including the base case presented in this study, it is observed that the net electrical efficiency of CLR-CCs can be improved to 46.5% (lower heating value of NG basis by producing high-pressure steam through heat recovery from the pre-combustion process streams and sending it to the Heat Recovery Steam Generator in the power plant.

  19. Generating clock signals for a cycle accurate, cycle reproducible FPGA based hardware accelerator

    Science.gov (United States)

    Asaad, Sameth W.; Kapur, Mohit

    2016-01-05

    A method, system and computer program product are disclosed for generating clock signals for a cycle accurate FPGA based hardware accelerator used to simulate operations of a device-under-test (DUT). In one embodiment, the DUT includes multiple device clocks generating multiple device clock signals at multiple frequencies and at a defined frequency ratio; and the FPG hardware accelerator includes multiple accelerator clocks generating multiple accelerator clock signals to operate the FPGA hardware accelerator to simulate the operations of the DUT. In one embodiment, operations of the DUT are mapped to the FPGA hardware accelerator, and the accelerator clock signals are generated at multiple frequencies and at the defined frequency ratio of the frequencies of the multiple device clocks, to maintain cycle accuracy between the DUT and the FPGA hardware accelerator. In an embodiment, the FPGA hardware accelerator may be used to control the frequencies of the multiple device clocks.

  20. Process modelling and techno-economic analysis of natural gas combined cycle integrated with calcium looping

    Directory of Open Access Journals (Sweden)

    Erans María

    2016-01-01

    Full Text Available Calcium looping (CaL is promising for large-scale CO2 capture in the power generation and industrial sectors due to the cheap sorbent used and the relatively low energy penalties achieved with this process. Because of the high operating temperatures the heat utilisation is a major advantage of the process, since a significant amount of power can be generated from it. However, this increases its complexity and capital costs. Therefore, not only the energy efficiency performance is important for these cycles, but also the capital costs must be taken into account, i.e. techno-economic analyses are required in order to determine which parameters and configurations are optimal to enhance technology viability in different integration scenarios. In this study the integration scenarios of CaL cycles and natural gas combined cycles (NGCC are explored. The process models of the NGCC and CaL capture plant are developed to explore the most promising scenarios for NGCC-CaL integration with regards to efficiency penalties. Two scenarios are analysed in detail, and show that the system with heat recovery steam generator (HRSG before and after the capture plant exhibited better performance of 49.1% efficiency compared with that of 45.7% when only one HRSG is located after the capture plant. However, the techno-economic analyses showed that the more energy efficient case, with two HRSGs, implies relatively higher cost of electricity (COE, 44.1€/MWh, when compared to that of the reference plant system (33.1€/MWh. The predicted cost of CO2 avoided for the case with two HRSGS is 29.3 €/ton CO2.

  1. Thermoeconomic evaluation and optimization of a Brayton–Rankine–Kalina combined triple power cycle

    International Nuclear Information System (INIS)

    Singh, Omendra Kumar; Kaushik, S.C.

    2013-01-01

    Highlights: • Combustion chamber performance can improve much by investment in efficient design. • Steam turbine performance would also improve by investment in efficient design. • Minimum total cost rate of plant found at gas cycle pressure ratio of around 14. • Total cost rate decreases significantly by decreasing the inlet air temperature. • Total cost rate decreases a little by increasing the inlet air relative humidity. - Abstract: This paper presents thermoeconomic analysis and optimization of a Brayton–Rankine–Kalina combined triple power cycle using Specific Exergy Costing (SPECO) methodology. Cost-balance and auxiliary equations are formulated for each component and for each node and solved through a MATLAB program to get the average cost per unit exergy at different state points. To evaluate the cost effectiveness of the system, the values of thermoeconomic variables for each component are calculated. Large relative cost difference is observed in the steam turbine, HRSG’s, combustion chambers, compressors, recuperators and ammonia–water evaporator. Therefore, these components require greater attention. The performance of steam turbine, combustion chambers, recuperators and ammonia–water evaporator can be appreciably improved by capital investment into more efficient design due to their low values of exergoeconomic factor. The performance of HRSG’s can be improved only marginally due to slightly higher value of exergoeconomic factor but no such recommendation can be made for the compressors which have a quite high value of exergoeconomic factor. The objective function of the thermoeconomic optimization is the minimization of the total cost rate for the whole plant. Its minimum value is found to occur at a gas cycle pressure ratio of around 14. Decreasing inlet air temperature decreases this objective function parameter significantly while increasing relative humidity causes a small decrease in it

  2. Thermoeconomic analysis of Biomass Integrated Gasification Gas Turbine Combined Cycle (BIG GT CC) cogeneration plant

    Energy Technology Data Exchange (ETDEWEB)

    Arrieta, Felipe Raul Ponce; Lora, Electo Silva [Escola Federal de Engenharia de Itajuba, MG (Brazil). Nucleo de Estudos de Sistemas Termicos]. E-mails: aponce@iem.efei.br; electo@iem.efei.br; Perez, Silvia Azucena Nebra de [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Energia]. E-mail: sanebra@fem. unicamp.br

    2000-07-01

    Using thermoeconomics as a tool to identify the location and magnitude of the real thermodynamic losses (energy waste, or exergy destruction and exergy losses) it is possible to assess the production costs of each product (electric power and heat) and the exergetic and exergoeconomic cost of each flow in a cogeneration plant to assist in decision-marketing procedures concerning to plant design, investment, operation and allocations of research funds. Thermo economic analysis of Biomass Integrated Gasification Gas Turbine Combined Cycle (BIG GT CC) cogeneration plant for its applications in sugar cane mills brings the following results: the global exergetic efficiency is low; the highest irreversibilities occur in the following equipment, by order: scrubber (38%), gas turbine (16%), dryer (12%), gasifier and HRSG (6%); due to the adopted cost distribution methodology, the unit exergetic cost of the heat (4,11) is lower than electricity (4,71); the lower market price of biomass is one of the most sensible parameter in the possible implementation of BIG-GT technology in sugar cane industry; the production costs are 31 US$/MWh and 32 US$/MWh for electricity and heat, respectively. The electricity cost is, after all, competitive with the actual market price. The electricity and heat costs are lower or almost equal than other values reported for actual Rankine cycle cogeneration plants. (author)

  3. A New Superalloy Enabling Heavy Duty Gas Turbine Wheels for Improved Combined Cycle Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Detor, Andrew [General Electric Company, Niskayuna, NY (United States). GE Global Research; DiDomizio, Richard [General Electric Company, Niskayuna, NY (United States). GE Global Research; McAllister, Don [The Ohio State Univ., Columbus, OH (United States); Sampson, Erica [General Electric Company, Niskayuna, NY (United States). GE Global Research; Shi, Rongpei [The Ohio State Univ., Columbus, OH (United States); Zhou, Ning [General Electric Company, Niskayuna, NY (United States). GE Global Research

    2017-01-03

    The drive to increase combined cycle turbine efficiency from 62% to 65% for the next-generation advanced cycle requires a new heavy duty gas turbine wheel material capable of operating at 1200°F and above. Current wheel materials are limited by the stability of their major strengthening phase (gamma double prime), which coarsens at temperatures approaching 1200°F, resulting in a substantial reduction in strength. More advanced gamma prime superalloys, such as those used in jet engine turbine disks, are also not suitable due to size constraints; the gamma prime phase overages during the slow cooling rates inherent in processing thick-section turbine wheels. The current program addresses this need by screening two new alloy design concepts. The first concept exploits a gamma prime/gamma double prime coprecipitation reaction. Through manipulation of alloy chemistry, coprecipitation is controlled such that gamma double prime is used only to slow the growth of gamma prime during slow cooling, preventing over-aging, and allowing for subsequent heat treatment to maximize strength. In parallel, phase field modeling provides fundamental understanding of the coprecipitation reaction. The second concept uses oxide dispersion strengthening to improve on two existing alloys that exhibit excellent hold time fatigue crack growth resistance, but have insufficient strength to be considered for gas turbine wheels. Mechanical milling forces the dissolution of starting oxide powders into a metal matrix allowing for solid state precipitation of new, nanometer scale oxides that are effective at dispersion strengthening.

  4. Conceptual design study of a coal gasification combined-cycle powerplant for industrial cogeneration

    Science.gov (United States)

    Bloomfield, H. S.; Nelson, S. G.; Straight, H. F.; Subramaniam, T. K.; Winklepleck, R. G.

    1981-01-01

    A conceptual design study was conducted to assess technical feasibility, environmental characteristics, and economics of coal gasification. The feasibility of a coal gasification combined cycle cogeneration powerplant was examined in response to energy needs and to national policy aimed at decreasing dependence on oil and natural gas. The powerplant provides the steam heating and baseload electrical requirements while serving as a prototype for industrial cogeneration and a modular building block for utility applications. The following topics are discussed: (1) screening of candidate gasification, sulfur removal and power conversion components; (2) definition of a reference system; (3) quantification of plant emissions and waste streams; (4) estimates of capital and operating costs; and (5) a procurement and construction schedule. It is concluded that the proposed powerplant is technically feasible and environmentally superior.

  5. Combined nutritional and environmental life cycle assessment of fruits and vegetables

    DEFF Research Database (Denmark)

    Stylianou, Katerina S.; Fantke, Peter; Jolliet, Olivier

    2016-01-01

    ; 35 μDALY/serving fruit benefit compared to a factor 10 lower impact. Replacing detrimental foods, such as trans-fat and red meat, with fruits or vegetables further enhances health benefit. This study illustrates the importance of considering nutritional effects in food-LCA.......Nutritional health effects from the ‘use stage’ of the life cycle of food products can be substantial, especially for fruits and vegetables. To assess potential one-serving increases in fruit and vegetable consumption in Europe, we employ the Combined Nutritional and Environmental LCA (CONE......-LCA) framework that compares environmental and nutritional effects of foods in a common end -point metric, Disability Adjusted Life Years (DALY). In the assessment, environmental health impact categories include green house gases, particulate matter (PM), and pesticide residues on fruits and vegetables, while...

  6. Family Life Cycle and Deforestation in Amazonia: Combining Remotely Sensed Information with Primary Data

    Science.gov (United States)

    Caldas, M.; Walker, R. T.; Shirota, R.; Perz, S.; Skole, D.

    2003-01-01

    This paper examines the relationships between the socio-demographic characteristics of small settlers in the Brazilian Amazon and the life cycle hypothesis in the process of deforestation. The analysis was conducted combining remote sensing and geographic data with primary data of 153 small settlers along the TransAmazon Highway. Regression analyses and spatial autocorrelation tests were conducted. The results from the empirical model indicate that socio-demographic characteristics of households as well as institutional and market factors, affect the land use decision. Although remotely sensed information is not very popular among Brazilian social scientists, these results confirm that they can be very useful for this kind of study. Furthermore, the research presented by this paper strongly indicates that family and socio-demographic data, as well as market data, may result in misspecification problems. The same applies to models that do not incorporate spatial analysis.

  7. Integrated gasification combined cycle versus supercritical pulverized coal for power generation from coal

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    Integrated Gasification Combined Cycle (IGCC) plants provide potential performance, environmental, and fuel flexibility advantages over more conventional combustion technologies such as Supercritical Pulverized Coal (SCPC) plants. Projected pollutant emissions from IGCC plants are the lowest of all coal power generation technologies. Mercury and carbon dioxide emissions reductions can be achieved at a much lower cost for IGCC plants than for conventional pulverized coal-fired power plants. Future IGCC developments, such as improvements in process technologies and development of larger, more efficient combustion turbines, offer the potential to further increase the competitiveness and performance of IGCC. For these reasons, IGCC is likely to evolve as the future technology of choice for generation of electricity from coal. An overview is presented of the components of an IGCC plant, along with a discussion of integration options and commercial status. IGCC plant performance and economics are compared against SCPC power generation for Chinese coals. 1 fig., 4 tabs.

  8. Evaluation of advanced coal gasification combined-cycle systems under uncertainty

    International Nuclear Information System (INIS)

    Frey, H.C.; Rubin, E.S.

    1992-01-01

    Advanced integrated gasification combined cycle (IGCC) systems have not been commercially demonstrated, and uncertainties remain regarding their commercial-scale performance and cost. Therefore, a probabilistic evaluation method has been developed and applied to explicitly consider these uncertainties. The insights afforded by this method are illustrated for an IGCC design featuring a fixed-bed gasifier and a hot gas cleanup system. Detailed case studies are conducted to characterize uncertainties in key measures of process performance and cost, evaluate design trade-offs under uncertainty, identify research priorities, evaluate the potential benefits of additional research, compare results for different uncertainty assumptions, and compare the advanced IGCC system to a conventional system under uncertainty. The implications of probabilistic results for research planning and technology selection are discussed in this paper

  9. Performance analysis of the MHD-steam combined cycle, including the influence of cost

    Science.gov (United States)

    Berry, G. F.; Dennis, C. B.

    1980-08-01

    A range of possible performance variables is explored in order to determine the sensitivity of a specific plant design to variation in key system parameters and, ultimately, to establish probable system performance limits. The comprehensive computer code that was developed analyzes and simulates an MHD plant for any number of different configurations, and holds constraints automatically while conducting either sensitivity studies or optimization. A summary of a sensitivity analysis conducted for a combined cycle, MHD steam power plant is presented. The influence of several of the more important system parameters were investigated and the results are presented in graphical form. The ANL cost algorithm is described and it is demonstrated that good agreement is obtained for the calculated cost of electricity.

  10. Thermodynamic and economic analysis of a gas turbine combined cycle plant with oxy-combustion

    Science.gov (United States)

    Kotowicz, Janusz; Job, Marcin

    2013-12-01

    This paper presents a gas turbine combined cycle plant with oxy-combustion and carbon dioxide capture. A gas turbine part of the unit with the operating parameters is presented. The methodology and results of optimization by the means of a genetic algorithm for the steam parts in three variants of the plant are shown. The variants of the plant differ by the heat recovery steam generator (HRSG) construction: the singlepressure HRSG (1P), the double-pressure HRSG with reheating (2PR), and the triple-pressure HRSG with reheating (3PR). For obtained results in all variants an economic evaluation was performed. The break-even prices of electricity were determined and the sensitivity analysis to the most significant economic factors were performed.

  11. Optimization of the oxidant supply system for combined cycle MHD power plants

    Science.gov (United States)

    Juhasz, A. J.

    1982-01-01

    An in-depth study was conducted to determine what, if any, improvements could be made on the oxidant supply system for combined cycle MHD power plants which could be reflected in higher thermal efficiency and a reduction in the cost of electricity, COE. A systematic analysis of air separation process varitions which showed that the specific energy consumption could be minimized when the product stream oxygen concentration is about 70 mole percent was conducted. The use of advanced air compressors, having variable speed and guide vane position control, results in additional power savings. The study also led to the conceptual design of a new air separation process, sized for a 500 MW sub e MHD plant, referred to a internal compression is discussed. In addition to its lower overall energy consumption, potential capital cost savings were identified for air separation plants using this process when constructed in a single large air separation train rather than multiple parallel trains, typical of conventional practice.

  12. Effect of the combined stress on the life of components under thermal cycling conditions

    International Nuclear Information System (INIS)

    Zuchowski, R.; Zietkowski, L.

    1987-01-01

    The life of structural components subjected to temperature changes is affected, among other factors, by the nature of the stress field. If life prediction for axially stressed components can be accomplished with a number of well established techniques, the behaviour under a complex state of stress and varying temperature conditions still is the object of intensive research. The present study was aimed at assessing the influence of the stress field upon the life of specimens made of chromium-nickel H23N18 steel under thermal cycling conditions. The designation of steel is in accordance with Polish Standards. The experiments were made on thin-walled tubular specimens loaded with various combinations of a static axial force and a static torque. (orig./GL)

  13. Coal-gasification/MHD/steam-turbine combined-cycle (GMS) power generation

    Energy Technology Data Exchange (ETDEWEB)

    Lytle, J.M.; Marchant, D.D.

    1980-11-01

    The coal-gasification/MHD/steam-turbine combined cycle (GMS) refers to magnetohydrodynamic (MHD) systems in which coal gasification is used to supply a clean fuel (free of mineral matter and sulfur) for combustion in an MHD electrical power plant. Advantages of a clean-fuel system include the elimination of mineral matter or slag from all components other than the coal gasifier and gas cleanup system; reduced wear and corrosion on components; and increased seed recovery resulting from reduced exposure of seed to mineral matter or slag. Efficiencies in some specific GMS power plants are shown to be higher than for a comparably sized coal-burning MHD power plant. The use of energy from the MHD exhaust gas to gasify coal (rather than the typical approach of burning part of the coal) results in these higher efficiencies.

  14. Valuing flexibility: The case of an Integrated Gasification Combined Cycle power plant

    International Nuclear Information System (INIS)

    Abadie, Luis M.; Chamorro, Jose M.

    2008-01-01

    In this paper we analyze the choice between two technologies for producing electricity. In particular, the firm has to decide whether and when to invest either in a Natural Gas Combined Cycle (NGCC) power plant or in an Integrated Gasification Combined Cycle (IGCC) power plant, which may burn either coal or natural gas. Instead of assuming that fuel prices follow standard geometric Brownian motions, here they are assumed to show mean reversion, specifically to follow an inhomogeneous geometric Brownian motion. First we consider the opportunity to invest in a NGCC power plant. We derive the optimal investment rule as a function of natural gas price and the remaining life of the right to invest. In addition, the analytical solution for a perpetual option to invest is obtained. Then we turn to the IGCC power plant. We analyse the valuation of an operating plant when there are switching costs between modes of operation, and the choice of the best operation mode. This serves as an input to evaluate the option to invest in this plant. Finally we derive the value of an opportunity to invest either in a NGCC or IGCC power plant, i.e. to choose between an inflexible and a flexible technology, respectively. Depending on the opportunity's time to maturity, we derive the pairs of coal and gas prices for which it is optimal to invest in NGCC, in IGCC, or simply not to invest. Numerical computations involve the use of one- and two-dimensional binomial lattices that support a mean-reverting process for coal and gas prices. Basic parameter values are taken from an actual IGCC power plant currently in operation. Sensitivity of some results with respect to the underlying stochastic process for fuel price is also checked

  15. A First Case Study of a Life Cycle-Based Alternatives Assessment (LCAA)

    DEFF Research Database (Denmark)

    Fantke, Peter; Huang, L.; Overcash, Michael

    2017-01-01

    various population groups including workers, consumers and the general public, while life cycle impacts need to focus on categories relevant for a given AA chemical-product application. We systematically define the scope of AA and identify key elements for quantitatively considering exposure and life...... cycle impacts. Our approach is evaluated in a case study, through which we outline future research needs to fully operationalize a consistent and Life Cycle-based Alternatives Assessment (LCAA). We build on a flexible mass balance-based modeling system yielding cumulative multimedia transfer fractions...... and exposure pathway-specific Product Intake Fractions defined as chemical mass taken in by humans per unit mass of chemical in a product. When combined with chemical masses in products and further with toxicity information, this approach is a resourceful way to inform AA. Our case study reveals that replacing...

  16. Effect of Curing Conditions and Freeze-Thaw Cycles on the Strength of an Expansive Soil Stabilized with a Combination of Lime, Jaggery, and Gallnut Powder

    Directory of Open Access Journals (Sweden)

    Jijo James

    2018-01-01

    Full Text Available This investigation involved the utilization of the combination of lime, jaggery, and gallnut powder, adopted in South India traditionally. This combination of materials, used for the manufacture of lime-based mortars, was adopted in stabilization of an expansive soil. Three combinations of lime, jaggery, and gallnut powder (LJG in the ratios of 8 : 2 : 2, 8 : 2 : 1, and 8 : 1 : 2 were put into use. The effect of subjecting the combinations to alternate cycles of freeze-thaw (up to 3 cycles and three different curing conditions of air, moisture, and heat was also investigated. In addition, a mineralogical investigation for studying the reaction products was also carried out. The investigation proceeded with the determination of the unconfined compression strength (UCS of stabilized specimens of dimensions 38 mm × 76 mm, cured for periods of 3, 7, 14, and 28 days. The results of the investigation revealed that the addition of LJG resulted in an increase in the strength of the stabilized soil. Freeze-thaw cycles resulted in a reduction in strength with LJG821 proving to be the most optimal combination developing the maximum strength and least strength loss due to freeze-thaw cycles. Thermal curing proved to be the most optimal curing condition out of all curing conditions evaluated.

  17. Research report for fiscal 1998. Basic research for promoting joint implementation, etc. (conversion of old coal-fired thermoelectric power plants in Poland into combined cycle plants); 1998 nendo chosa hokokusho. Poland sekitan karyoku hatsudensho (kyushiki) combined cycle eno tenkan

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    A project is discussed for modernization for energy efficiency enhancement and greenhouse gas reduction. The most effective way to reduce greenhouse gas in Poland is to totally replace the existing coal-fired power plants with natural gas combined cycle plants. Under this project, however, natural gas-fired power generation and integrated coal/brown coal gasification combined cycle power generation are both subjected to study. This is because the power plant modernization project is closely related to the fate of coal/brown coal industries which constitute the important industrial department of Poland. As for the earning rate of the project in case of natural gas-fired combined cycle power generation, the rate will be 13.2% even at the Kaweczyn station which is the highest in earning rate, and this fails to satisfy the project conditions. If integrated coal/brown gasification combined cycle power generation is chosen, the rate will be still lower. When the cost for greenhouse gas reduction is taken up, the Konin station exhibits the lowest of 9 dollars/tCO2, and the others 15-17 dollars/tCO2. When coal gas combined cycle is employed, the cost will be 3-4 times higher. (NEDO)

  18. Combining life cycle assessment and qualitative risk assessment: the case study of alumina nanofluid production.

    Science.gov (United States)

    Barberio, Grazia; Scalbi, Simona; Buttol, Patrizia; Masoni, Paolo; Righi, Serena

    2014-10-15

    In this paper the authors propose a framework for combining life cycle assessment (LCA) and Risk Assessment (RA) to support the sustainability assessment of emerging technologies. This proposal includes four steps of analysis: technological system definition; data collection; risk evaluation and impacts quantification; results interpretation. This scheme has been applied to a case study of nanofluid alumina production in two different pilot lines, "single-stage" and "two-stage". The study has been developed in the NanoHex project (enhanced nano-fluid heat exchange). Goals of the study were analyzing the hotspots and highlighting possible trade-off between the results of LCA, which identifies the processes having the best environmental performance, and the results of RA, which identifies the scenarios having the highest risk for workers. Indeed, due to lack of data about exposure limits, exposure-dose relationships and toxicity of alumina nanopowders (NPs) and nanofluids (NF), the workplace exposure has been evaluated by means of qualitative risk assessment, using Stoffenmanager Nano. Though having different aims, LCA and RA have a complementary role in the description of impacts of products/substances/technologies. Their combined use can overcome limits of each of them and allows a wider vision of the problems to better support the decision making process. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Field operation test of Wakamatsu PFBC combined cycle power plant; Wakamatsu PFBC jissho shiken no genkyo

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, T. [Center for Coal Utilization, Japan, Tokyo (Japan); Takanishi, K. [Electric Power Development Co. Ltd., Tokyo (Japan)

    1996-09-01

    At the Wakamatsu Coal Utilization Research Center, the verification test was conducted of atmospheric pressure fluidized bed boilers and ultra-high temperature turbines. The Wakamatsu PFBC (pressurized fluidized bed combustion) is a combined cycle power generation system combining steam turbine power generation in which the turbine is driven by steam generated from the fluidized bed boiler installed inside the pressure vessel and gas turbine power generation in which high temperature/pressure exhaust gas is used from the boiler, having a total output of 71 MW. The operation started in fiscal 1995, stopped due to damage of the tube of CTF (ceramic tube filter), and is now continuing after the repair. As a result of the test conducted in fiscal 1995, it was confirmed in the two-stage cyclone test that the diameter of ash particle and cyclone efficiency change by kind of coal and amount of limestone and that by coal kind gas turbine blades show different states of abrasion, indicating greater abrasion when there is much SiO2 in ash. As a result of the continued high load operation of CTF, ash blockade inside the tube occurred and tube damage was generated by thermal shock, etc. 5 figs., 4 tabs.

  20. Optimisation of environmental gas cleaning routes for solid wastes cogeneration systems. Part II - Analysis of waste incineration combined gas/steam cycle

    International Nuclear Information System (INIS)

    Holanda, Marcelo R.; Perrella Balestieri, Jose A.

    2008-01-01

    In the first paper of this paper (Part I), conditions were presented for the gas cleaning technological route for environomic optimisation of a cogeneration system based in a thermal cycle with municipal solid waste incineration. In this second part, an environomic analysis is presented of a cogeneration system comprising a combined cycle composed of a gas cycle burning natural gas with a heat recovery steam generator with no supplementary burning and a steam cycle burning municipal solid wastes (MSW) to which will be added a pure back pressure steam turbine (another one) of pure condensation. This analysis aims to select, concerning some scenarios, the best atmospheric pollutant emission control routes (rc) according to the investment cost minimisation, operation and social damage criteria. In this study, a comparison is also performed with the results obtained in the Case Study presented in Part I

  1. Mathematical Modeling – The Impact of Cooling Water Temperature Upsurge on Combined Cycle Power Plant Performance and Operation

    Science.gov (United States)

    Indra Siswantara, Ahmad; Pujowidodo, Hariyotejo; Darius, Asyari; Ramdlan Gunadi, Gun Gun

    2018-03-01

    This paper presents the mathematical modeling analysis on cooling system in a combined cycle power plant. The objective of this study is to get the impact of cooling water upsurge on plant performance and operation, using Engineering Equation Solver (EES™) tools. Power plant installed with total power capacity of block#1 is 505.95 MWe and block#2 is 720.8 MWe, where sea water consumed as cooling media at two unit condensers. Basic principle of analysis is heat balance calculation from steam turbine and condenser, concern to vacuum condition and heat rate values. Based on the result shown graphically, there were impact the upsurge of cooling water to increase plant heat rate and vacuum pressure in condenser so ensued decreasing plant efficiency and causing possibility steam turbine trip as back pressure raised from condenser.

  2. Development of life cycle water-demand coefficients for coal-based power generation technologies

    International Nuclear Information System (INIS)

    Ali, Babkir; Kumar, Amit

    2015-01-01

    Highlights: • We develop water consumption and withdrawals coefficients for coal power generation. • We develop life cycle water footprints for 36 coal-based electricity generation pathways. • Different coal power generation technologies were assessed. • Sensitivity analysis of plant performance and coal transportation on water demand. - Abstract: This paper aims to develop benchmark coefficients for water consumption and water withdrawals over the full life cycle of coal-based power generation. This study considered not only all of the unit operations involved in the full electricity generation life cycle but also compared different coal-based power generating technologies. Overall this study develops the life cycle water footprint for 36 different coal-based electricity generation pathways. Power generation pathways involving new technologies of integrated gasification combined cycle (IGCC) or ultra supercritical technology with coal transportation by conventional means and using dry cooling systems have the least complete life cycle water-demand coefficients of about 1 L/kW h. Sensitivity analysis is conducted to study the impact of power plant performance and coal transportation on the water demand coefficients. The consumption coefficient over life cycle of ultra supercritical or IGCC power plants are 0.12 L/kW h higher when conventional transportation of coal is replaced by coal-log pipeline. Similarly, if the conventional transportation of coal is replaced by its transportation in the form of a slurry through a pipeline, the consumption coefficient of a subcritical power plant increases by 0.52 L/kW h

  3. Application of the Combined Cycle LWR-Gas Turbine to PWR for NPP Life Extension Safety Upgrade and Improving Economy

    International Nuclear Information System (INIS)

    Kuznetsov, Yu. N.

    2006-01-01

    Currently, some of the most important problem for the nuclear industry are life extension, advance competitiveness and safety of aging LWR NPPs. Based on results of studies performed in the USA (Battelle Memorial Institute) and in Russia (NIKIET), a new power technology, using a combined cycle gas-turbine facility CCGT - LWR, so called TD-Cycle, can significantly help in resolution of some problems of nuclear power industry. The nuclear steam and gas topping cycle is used for re-powering a light water pressurized reactor of PWR or VVER type. An existing NPP is topped with a gas turbine facility with a heat recovery steam generator (HRSG) generating steam from waste heat. The superheated steam of high pressure (P=90-165 bar, T=500-550 C) generated in the HRSG, is expanded in a high pressure (HP) turbine for producing electricity. The HP turbine can work on one shaft with the the gas turbine or at one shaft with intermediate (IP) or low (LP) pressure parts of the main nuclear steam turbine, or with a separate electric generator. The exhausted steam from the HP turbine is injected into the steam mixer where it is mixed with the saturated steam from the NPP steam generator (SG). The mixer is intended to superheat the main nuclear steam and should be characterized by minimum losses during mixing superheated and saturated steam. Steam from the mixer superheated by 20-60 C directs to the existing IP turbine, and then, through a separator-reheater flows into the LP turbine. Feed water re-heaters of LP and HP are actually unchanged in this case. Feed water extraction to the HRSG is supplied after one of LP water heaters. This proposal is intended to re-power existing LWR NPPs. To minimize cost, the IP and LP turbines and electric generator would remain the same. The reactor thermal power and fast neutron flux to the reactor vessel would decrease by 30-50 percent of nominal values. The external peripheral row of fuel elements can be replaced with metal absorber rods to

  4. Research on development model of nuclear component based on life cycle management

    International Nuclear Information System (INIS)

    Bao Shiyi; Zhou Yu; He Shuyan

    2005-01-01

    At present the development process of nuclear component, even nuclear component itself, is more and more supported by computer technology. This increasing utilization of the computer and software has led to the faster development of nuclear technology on one hand and also brought new problems on the other hand. Especially, the combination of hardware, software and humans has increased nuclear component system complexities to an unprecedented level. To solve this problem, Life Cycle Management technology is adopted in nuclear component system. Hence, an intensive discussion on the development process of a nuclear component is proposed. According to the characteristics of the nuclear component development, such as the complexities and strict safety requirements of the nuclear components, long-term design period, changeable design specifications and requirements, high capital investment, and satisfaction for engineering codes/standards, the development life-cycle model of nuclear component is presented. The development life-cycle model is classified at three levels, namely, component level development life-cycle, sub-component development life-cycle and component level verification/certification life-cycle. The purposes and outcomes of development processes are stated in detailed. A process framework for nuclear component based on system engineering and development environment of nuclear component is discussed for future research work. (authors)

  5. Modelling and exergoeconomic-environmental analysis of combined cycle power generation system using flameless burner for steam generation

    International Nuclear Information System (INIS)

    Hosseini, Seyed Ehsan; Barzegaravval, Hasan; Ganjehkaviri, Abdolsaeid; Wahid, Mazlan Abdul; Mohd Jaafar, M.N.

    2017-01-01

    Highlights: • Using flameless burner as a supplementary firing system after gas turbine is modeled. • Thermodynamic, economic and environmental analyses of this model are performed. • Efficiency of the plant increases about 6% and CO 2 emission decreases up to 5.63% in this design. • Available exergy for work production in both gas cycle and steam cycle increases in this model. - Abstract: To have an optimum condition for the performance of a combined cycle power generation, using supplementary firing system after gas turbine was investigated by various researchers. Since the temperature of turbine exhaust is higher than auto-ignition temperature of the fuel in optimum condition, using flameless burner is modelled in this paper. Flameless burner is installed between gas turbine cycle and Rankine cycle of a combined cycle power plant which one end is connected to the outlet of gas turbine (as primary combustion oxidizer) and the other end opened to the heat recovery steam generator. Then, the exergoeconomic-environmental analysis of the proposed model is evaluated. Results demonstrate that efficiency of the combined cycle power plant increases about 6% and CO 2 emission reduces up to 5.63% in this proposed model. It is found that the variation in the cost is less than 1% due to the fact that a cost constraint is implemented to be equal or lower than the design point cost. Moreover, exergy of flow gases increases in all points except in heat recovery steam generator. Hence, available exergy for work production in both gas cycle and steam cycle will increase in new model.

  6. Biomass from agriculture in small-scale combined heat and power plants - A comparative life cycle assessment

    International Nuclear Information System (INIS)

    Kimming, M.; Sundberg, C.; Nordberg, A.; Baky, A.; Bernesson, S.; Noren, O.; Hansson, P.-A.

    2011-01-01

    Biomass produced on farm land is a renewable fuel that can prove suitable for small-scale combined heat and power (CHP) plants in rural areas. However, it can still be questioned if biomass-based energy generation is a good environmental choice with regards to the impact on greenhouse gas emissions, and if there are negative consequences of using of agricultural land for other purposes than food production. In this study, a simplified life cycle assessment (LCA) was conducted over four scenarios for supply of the entire demand of power and heat of a rural village. Three of the scenarios are based on utilization of biomass in 100 kW (e) combined heat and power (CHP) systems and the fourth is based on fossil fuel in a large-scale plant. The biomass systems analyzed were based on 1) biogas production with ley as substrate and the biogas combusted in a microturbine, 2) gasification of willow chips and the product gas combusted in an IC-engine and 3) combustion of willow chips for a Stirling engine. The two first scenarios also require a straw boiler. The results show that the biomass-based scenarios reduce greenhouse gas emissions considerably compared to the scenario based on fossil fuel, but have higher acidifying emissions. Scenario 1 has by far the best performance with respect to global warming potential and the advantage of utilizing a byproduct and thus not occupying extra land. Scenario 2 and 3 require less primary energy and less fossil energy input than 1, but set-aside land for willow production must be available. The low electric efficiency of scenario 3 makes it an unsuitable option.

  7. Integrated approach for characterizing and comparing exposure-based impacts with life cycle impacts

    DEFF Research Database (Denmark)

    Fantke, Peter; Jolliet, Olivier

    2016-01-01

    to the environment from product-related processes along the product life cycle. We build on a flexible mass balance-based modeling system yielding cumulative multimedia transfer fractions and exposure pathway-specific Product Intake Fractions defined as chemical mass taken in by humans per unit mass of chemical......To address hazardous chemicals in consumer products, chemical alternatives assessment (CAA) is an emerging approach combining hazard and exposure assessment with technical and economic feasibility. Life cycle aspects are typically not consistently considered in CAA, but are relevant to avoid decis...... cycle emissions of potentially harmful chemicals and their proposed replacements. Hence, an assessment framework is required that is able to account for near-field consumer exposure to chemicals in products during and after product use as well as population far-field exposure to chemical emissions...

  8. The effectiveness of community-based cycling promotion: findings from the Cycling Connecting Communities project in Sydney, Australia

    Directory of Open Access Journals (Sweden)

    Merom Dafna

    2010-01-01

    Full Text Available Abstract Background Encouraging cycling is an important way to increase physical activity in the community. The Cycling Connecting Communities (CCC Project is a community-based cycling promotion program that included a range of community engagement and social marketing activities, such as organised bike rides and events, cycling skills courses, the distribution of cycling maps of the area and coverage in the local press. The aim of the study was to assess the effectiveness of this program designed to encourage the use of newly completed off-road cycle paths through south west Sydney, Australia. Methods The evaluation used a quasi-experimental design that consisted of a pre- and post-intervention telephone survey (24 months apart of a cohort of residents (n = 909 in the intervention area (n = 520 (Fairfield and Liverpool and a socio-demographically similar comparison area (n = 389 (Bankstown. Both areas had similar bicycle infrastructure. Four bicycle counters were placed on the main bicycle paths in the intervention and comparison areas to monitor daily bicycle use before and after the intervention. Results The telephone survey results showed significantly greater awareness of the Cycling Connecting Communities project (13.5% vs 8.0%, p Conclusion Despite relatively modest resources, the Cycling Connecting Communities project achieved significant increases in bicycle path use, and increased cycling in some sub-groups. However, this community based intervention with limited funding had very limited reach into the community and did not increase population cycling levels.

  9. Lifetime Assessment of Combined Cycles for Cogeneration of Power and Heat in Offshore Oil and Gas Installations

    Directory of Open Access Journals (Sweden)

    Luca Riboldi

    2017-05-01

    Full Text Available The utilization of combined cycles for offshore cogeneration of power and heat is an attractive option to reduce the CO2 emissions directly related to the oil and gas sector. Main challenges for their efficient implementation are the potentially large heat-to-power ratios and the variability of power and heat requirements throughout the different stages of a field’s lifetime. This paper aimed to provide the first elements for an assessment of the technology. Two combined cycle configurations were evaluated (backpressure and extraction steam turbine cycle, as well as different scenarios of power and heat requirements. The optimum design approach was firstly investigated. Designing the combined cycle at the end-life conditions, rather than at peak conditions, demonstrated to return better overall performance, when the entire plant’s lifetime is considered. A comparative analysis between the defined optimum designs was then carried out. Although the backpressure steam turbine cycle demonstrated to be feasible in all the cases analyzed, it showed to be effective only for offshore installations characterized by low temperature large process heat demands. On the other hand, the extraction steam turbine cycle could not meet large process heat demands but it was very attractive when the heat requirements were more limited, irrespective of the temperature at which this heat was requested.

  10. Nasal base narrowing: the combined alar base excision technique.

    Science.gov (United States)

    Foda, Hossam M T

    2007-01-01

    To evaluate the role of the combined alar base excision technique in narrowing the nasal base and correcting excessive alar flare. The study included 60 cases presenting with a wide nasal base and excessive alar flaring. The surgical procedure combined an external alar wedge resection with an internal vestibular floor excision. All cases were followed up for a mean of 32 (range, 12-144) months. Nasal tip modification and correction of any preexisting caudal septal deformities were always completed before the nasal base narrowing. The mean width of the external alar wedge excised was 7.2 (range, 4-11) mm, whereas the mean width of the sill excision was 3.1 (range, 2-7) mm. Completing the internal excision first resulted in a more conservative external resection, thus avoiding any blunting of the alar-facial crease. No cases of postoperative bleeding, infection, or keloid formation were encountered, and the external alar wedge excision healed with an inconspicuous scar that was well hidden in the depth of the alar-facial crease. Finally, the risk of notching of the alar rim, which can occur at the junction of the external and internal excisions, was significantly reduced by adopting a 2-layered closure of the vestibular floor (P = .01). The combined alar base excision resulted in effective narrowing of the nasal base with elimination of excessive alar flare. Commonly feared complications, such as blunting of the alar-facial crease or notching of the alar rim, were avoided by using simple modifications in the technique of excision and closure.

  11. Recovery Act: Brea California Combined Cycle Electric Generating Plant Fueled by Waste Landfill Gas

    Energy Technology Data Exchange (ETDEWEB)

    Galowitz, Stephen

    2012-12-31

    The primary objective of the Project was to maximize the productive use of the substantial quantities of waste landfill gas generated and collected at the Olinda Landfill near Brea, California. An extensive analysis was conducted and it was determined that utilization of the waste gas for power generation in a combustion turbine combined cycle facility was the highest and best use. The resulting Project reflected a cost effective balance of the following specific sub-objectives: • Meeting the environmental and regulatory requirements, particularly the compliance obligations imposed on the landfill to collect, process and destroy landfill gas • Utilizing proven and reliable technology and equipment • Maximizing electrical efficiency • Maximizing electric generating capacity, consistent with the anticipated quantities of landfill gas generated and collected at the Olinda Landfill • Maximizing equipment uptime • Minimizing water consumption • Minimizing post-combustion emissions • The Project produced and will produce a myriad of beneficial impacts. o The Project created 360 FTE construction and manufacturing jobs and 15 FTE permanent jobs associated with the operation and maintenance of the plant and equipment. o By combining state-of-the-art gas clean up systems with post combustion emissions control systems, the Project established new national standards for best available control technology (BACT). o The Project will annually produce 280,320 MWh’s of clean energy o By destroying the methane in the landfill gas, the Project will generate CO2 equivalent reductions of 164,938 tons annually. The completed facility produces 27.4 MWnet and operates 24 hours a day, seven days a week.

  12. Sustainable renewable energy seawater desalination using combined-cycle solar and geothermal heat sources

    KAUST Repository

    Missimer, Thomas M.

    2013-01-01

    Key goals in the improvement of desalination technology are to reduce overall energy consumption, make the process "greener," and reduce the cost of the delivered water. Adsorption desalination (AD) is a promising new technology that has great potential to reduce the need for conventional power, to use solely renewable energy sources, and to reduce the overall cost of water treatment. This technology can desalt seawater or water of even higher salinity using waste heat, solar heat, or geothermal heat. An AD system can operate effectively at temperatures ranging from 55 to 80 °C with perhaps an optimal temperature of 80 °C. The generally low temperature requirement for the feedwater allows the system to operate quite efficiently using an alternative energy source, such as solar power. Solar power, particularly in warm dry regions, can generate a consistent water temperature of about 90 °C. Although this temperature is more than adequate to run the system, solar energy collection only can occur during daylight hours, thereby necessitating the use of heat storage during nighttime or very cloudy days. With increasing capacity, the need for extensive thermal storage may be problematic and could add substantial cost to the development of an AD system. However, in many parts of the world, there are subsurface geothermal energy sources that have not been extensively used. Combining a low to moderate geothermal energy recovery system to an AD system would provide a solution to the thermal storage issue. However, geothermal energy development from particularly Hot Dry Rock is limited by the magnitude of the heat flow required for the process and the thermal conductivity of the rock material forming the heat reservoir. Combining solar and geothermal energy using an alternating 12-h cycle would reduce the probability of depleting the heat source within the geothermal reservoir and provide the most effective use of renewable energy. © 2013 Desalination Publications.

  13. Energy and Exergy Analyses of a Combined Power Cycle Using the Organic Rankine Cycle and the Cold Energy of Liquefied Natural Gas

    Directory of Open Access Journals (Sweden)

    Ho Yong Lee

    2015-09-01

    Full Text Available In this work, energy and exergy analyses are carried out for a combined cycle consisting of an organic Rankine cycle (ORC and a liquefied natural gas (LNG Rankine cycle for the recovery of low-grade heat sources and LNG cold energy. The effects of the turbine inlet pressure and the working fluid on the system performance are theoretically investigated. A modified temperature-enthalpy diagram is proposed, which can be useful to see the characteristics of the combined cycle, as well as the temperature distributions in the heat exchangers. Results show that the thermal efficiency increases with an increasing turbine inlet pressure and critical temperature of the working fluid. However, the exergy efficiency has a peak value with respect to the turbine inlet pressure, and the maximum exergy efficiency and the corresponding optimum turbine inlet pressure are significantly influenced by the selection of the working fluid. The exergy destruction at the condenser is generally the greatest among the exergy destruction components of the system.

  14. Exergoeconomic assessment and parametric study of a Gas Turbine-Modular Helium Reactor combined with two Organic Rankine Cycles

    International Nuclear Information System (INIS)

    Mohammadkhani, F.; Shokati, N.; Mahmoudi, S.M.S.; Yari, M.; Rosen, M.A.

    2014-01-01

    An exergoeconomic analysis is reported for a combined system with a net electrical output of 299 MW in which waste heat from a Gas Turbine-Modular Helium Reactor (GT-MHR) is utilized by two Organic Rankine Cycles (ORCs). A parametric study is also done to reveal the effects on the exergoeconomic performance of the combined system of such significant parameters as compressor pressure ratio, turbine inlet temperature, temperatures of evaporators, pinch point temperature difference in the evaporators and degree of superheat at the ORC (Organic Rankine Cycle) turbines inlet. Finally the combined cycle performance is optimized from the viewpoint of exergoeconomics. The results show that the precooler, the intercooler and the ORC condensers exhibit the worst exergoeconomic performance. For the overall system, the exergoeconomic factor, the capital cost rate and the exergy destruction cost rate are determined to be 37.95%, 6876 $/h and 11,242 $/h, respectively. Also, it is observed that the unit cost of electricity produced by the GT-MHR turbine increases with increasing GT-MHR turbine inlet temperature but decreases as the other above mentioned parameters increase. - Highlights: • An exergoeconomic analysis is performed for the GT-MHR/ORC (Organic Rankine Cycle) combined cycle. • The effects of decision parameters on the exergoeconomic performance are studied. • The highest exergy destructions occur in the precooler, intercooler and condenser. • Superheating the working fluid at the ORC turbine inlet is not necessary. • Thermodynamic and exergoeconomic optimal conditions differ from each other

  15. New regimens with combined oral contraceptive pills--moving away from traditional 21/7 cycles.

    Science.gov (United States)

    Read, Christine M

    2010-12-01

    The practice of extending combined oral contraceptive use (COC) and eliminating or reducing the hormone free interval has been in use for many years. More recently a range of products with new dosing options has been developed and marketed. Women and physicians in developed countries are comfortable with and many prefer the use of extended COC regimens which provide an option to eliminate or reduce the frequency of regular withdrawal bleeding. The extension of active pill taking and the reduction or elimination of the hormone-free interval have been shown to be beneficial for women who experience menstrual cycle-related problems such as heavy bleeding or dysmenorrhoea. The hormone-free interval of less than seven days has additional benefits in managing hormone withdrawal symptoms and efficacy may be improved in situations where pills are inadvertently missed or in women who are perceived as 'poor' pill takers. This paper provides a descriptive review highlighting the development of new dosing options that alter the traditional 21/7 COC regimen. The rationale for and the acceptability of COCs developed with alternative dosing regimens is examined.

  16. Coal waste slurries as a fuel for integrated gasification combined cycle plants

    Directory of Open Access Journals (Sweden)

    Lutynski Marcin A.

    2016-01-01

    Full Text Available The article summarizes recent development in integrated gasification combined cycle technology and lists existing and planned IGCC plants. A brief outlook on the IGCC gasification technology is given with focus on entrained-flow gasifiers where the low-quality coal waste slurry fuel can be used. Desired properties of coal and ash for entrained-flow gasifiers are listed. The coal waste slurries, which were deposited at impoundments in Upper Silesian Coal Basin, were considered as a direct feed for such gasifiers. The average ash content, moisture content and lower heating value were analysed and presented as an average values. Entrained-flow commercial gasifiers can be considered as suitable for the coal slurry feed, however the ash content of coal slurries deposited in impoundments is too high for the direct use as the feed for the gasifiers. The moisture content of slurries calculated on as received basis meets the requirements of entrained-flow slurry feed gasifiers. The content of fines is relatively high which allow to use the slurries in entrained-flow gasifiers.

  17. Combustion Engineering Integrated Coal Gasification Combined Cycle Repowering Project: Clean Coal Technology Program

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    On February 22, 1988, DOE issued Program Opportunity Notice (PON) Number-DE-PS01-88FE61530 for Round II of the CCT Program. The purpose of the PON was to solicit proposals to conduct cost-shared ICCT projects to demonstrate technologies that are capable of being commercialized in the 1990s, that are more cost-effective than current technologies, and that are capable of achieving significant reduction of SO[sub 2] and/or NO[sub x] emissions from existing coal burning facilities, particularly those that contribute to transboundary and interstate pollution. The Combustion Engineering (C-E) Integrated Coal Gasification Combined Cycle (IGCC) Repowering Project was one of 16 proposals selected by DOE for negotiation of cost-shared federal funding support from among the 55 proposals that were received in response to the PON. The ICCT Program has developed a three-level strategy for complying with the National Environmental Policy Act (NEPA) that is consistent with the President's Council on Environmental Quality regulations implementing NEPA (40 CFR 1500-1508) and the DOE guidelines for compliance with NEPA (10 CFR 1021). The strategy includes the consideration of programmatic and project-specific environmental impacts during and subsequent to the reject selection process.

  18. Performance analysis of the MHD-steam combined cycle, including the influence of cost

    Energy Technology Data Exchange (ETDEWEB)

    Berry, G. F.; Dennis, C. B.

    1980-08-01

    The MHD Systems group of the ANL Engineering Division is conducting overall system studies, utilizing the computer simulation code that has been developed at ANL. This analytical investigation is exploring a range of possible performance variables, in order to determine the sensitivity of a specific plant design to variation in key system parameters and, ultimately, to establish probable system performance limits. The comprehensive computer code that has been developed for this task will analyze and simulate an MHD power plant for any number of different configurations, and will hold constraints automatically while conducting either sensitivity studies or optimization. A summary of a sensitivity analysis conducted for a combined cycle, MHD-steam power plant is presented. The influence of several of the more important systems parameters were investigated in a systematic fashion, and the results are presented in graphical form. The report is divided into four sections. Following the introduction, the second section describes in detail the results of a validation study conducted to insure that the code is functioning correctly. The third section includes a description of the ANL cost algorithm and a detailed comparison between the ANL cost results and published OCMHD cost information. it is further demonstrated in this section that good agreement is obtained for the calculated cost of electricity. The fourth section is a sensitivity study and optimization for a specific OCMHD configuration over several key plant parameters.

  19. The C-N-cycle additional channels through the combinative resonances phenomenon (CIRs)

    International Nuclear Information System (INIS)

    Gafarov, A.A.; Khugaev, A.V.; Koblik, Yu.N.

    2000-01-01

    The Combinative Isobar Resonances are shown as new channels of the C-N-cycle. In 1994 we had firstly used our new developed approach - the M ethod of Spectra Superposition p roviding measurement of d σ (E) /d ω at every accelerator (including colliders ) with highest energy-resolution depending (for thin targets) only on energy-resolution of detectors [1-5]. Rarely one can read about this[6].That time the Excitation Function (EF) of the l2 C(p,p o ) elastic scattering with energy-resolution ∼10 keV for E p =16 ∼ 19.5 MeV of cyclotron protons by using the multi angular magnetic spectrograph as detector was measured.It was wonderful when after data processing so surprised curve with a saturated structure of overlapped resonances - fluctuations of cross-section (Fig.1) was obtained (in contrary to EF obtained by M.J. LeVine and P.D.Parker in 60 Th at the tandem generator [7]). The precise agreement between well known thresholds and nuclear levels with the brightest anomalies in our curve and not disappearing fine structures in full-events curve (stat.err. 3%) - all this, only, had satisfied me that these structures are not just a joke of statistics. Fig.l shows a comparison of our obtained EF with thresholds and levels of well known product-nuclei

  20. A comparative study of biomass integrated gasification combined cycle power systems: Performance analysis.

    Science.gov (United States)

    Zang, Guiyan; Tejasvi, Sharma; Ratner, Albert; Lora, Electo Silva

    2018-05-01

    The Biomass Integrated Gasification Combined Cycle (BIGCC) power system is believed to potentially be a highly efficient way to utilize biomass to generate power. However, there is no comparative study of BIGCC systems that examines all the latest improvements for gasification agents, gas turbine combustion methods, and CO 2 Capture and Storage options. This study examines the impact of recent advancements on BIGCC performance through exergy analysis using Aspen Plus. Results show that the exergy efficiency of these systems is ranged from 22.3% to 37.1%. Furthermore, exergy analysis indicates that the gas turbine with external combustion has relatively high exergy efficiency, and Selexol CO 2 removal method has low exergy destruction. Moreover, the sensitivity analysis shows that the system exergy efficiency is more sensitive to the initial temperature and pressure ratio of the gas turbine, whereas has a relatively weak dependence on the initial temperature and initial pressure of the steam turbine. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Numerical Simulation of Fluidized Bed Gasifier for Integrated Gasification Combined Cycle

    Directory of Open Access Journals (Sweden)

    CHEN Ju-hui

    2017-06-01

    Full Text Available The overall thermal efficiency of the integrated gasification combined cycle ( IGCC has not been sufficiently improved. In order to achieve higher power generation efficiency,the advanced technology of IGCC has been developed which is on the basis of the concept of exergy recovery. IGCC systems and devices from the overall structure of opinion,this technology will generate electricity for the integration of advanced technology together,the current utilization of power generation technology and by endothermic reaction of steam in the gasifier,a gas turbine exhaust heat recovery or the solid oxide fuel cell. It is estimated that such the use of exergy recycling has the advantage of being easy to use,separating,collecting fixed CO2,making it very attractive,and can increase the overall efficiency by 10% or more. The characteristics of fluidized bed gasifier,one of the core equipment of the IGCC system,and its effect on the whole system were studied.

  2. Hybrid life cycle assessment (LCA) does not necessarily yield more accurate results than process-based LCA

    NARCIS (Netherlands)

    Yang, Yi; Heijungs, Reinout; Brandão, Miguel

    2017-01-01

    Hybrid life cycle assessment (LCA), through combining input-output (IO) models and process-based LCA for a complete system boundary, is widely recognized as a more accurate approach than process-based LCA with an incomplete system boundary. Without a complete process model for verification, however,

  3. Effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance.

    Science.gov (United States)

    Glaister, Mark; Pattison, John R; Muniz-Pumares, Daniel; Patterson, Stephen D; Foley, Paul

    2015-01-01

    The aim of this study was to examine the acute supplementation effects of dietary nitrate, caffeine, and their combination on 20-km cycling time trial performance. Using a randomized, counterbalanced, double-blind Latin-square design, 14 competitive female cyclists (age: 31 ± 7 years; height: 1.69 ± 0.07 m; body mass: 61.6 ± 6.0 kg) completed four 20-km time trials on a racing bicycle fitted to a turbo trainer. Approximately 2.5 hours before each trial, subjects consumed a 70-ml dose of concentrated beetroot juice containing either 0.45 g of dietary nitrate or with the nitrate content removed (placebo). One hour before each trial, subjects consumed a capsule containing either 5 mg·kg of caffeine or maltodextrin (placebo). There was a significant effect of supplementation on power output (p = 0.001), with post hoc tests revealing higher power outputs in caffeine (205 ± 21 W) vs. nitrate (194 ± 22 W) and placebo (194 ± 25 W) trials only. Caffeine-induced improvements in power output corresponded with significantly higher measures of heart rate (caffeine: 166 ± 12 b·min vs. placebo: 159 ± 15 b·min; p = 0.02), blood lactate (caffeine: 6.54 ± 2.40 mmol·L vs. placebo: 4.50 ± 2.11 mmol·L; p caffeine: 0.95 ± 0.04 vs. placebo: 0.91 ± 0.05; p = 0.03). There were no effects (p ≥ 0.05) of supplementation on cycling cadence, rating of perceived exertion, (Equation is included in full-text article.), or integrated electromyographic activity. The results of this study support the well-established beneficial effects of caffeine supplementation on endurance performance. In contrast, acute supplementation with dietary nitrate seems to have no effect on endurance performance and adds nothing to the benefits afforded by caffeine supplementation.

  4. Development of Natural Gas Fired Combined Cycle Plant for Tri-Generation of Power, Cooling and Clean Water Using Waste Heat Recovery: Techno-Economic Analysis

    Directory of Open Access Journals (Sweden)

    Gowtham Mohan

    2014-10-01

    Full Text Available Tri-generation is one of the most efficient ways for maximizing the utilization of available energy. Utilization of waste heat (flue gases liberated by the Al-Hamra gas turbine power plant is analyzed in this research work for simultaneous production of: (a electricity by combining steam rankine cycle using heat recovery steam generator (HRSG; (b clean water by air gap membrane distillation (AGMD plant; and (c cooling by single stage vapor absorption chiller (VAC. The flue gases liberated from the gas turbine power cycle is the prime source of energy for the tri-generation system. The heat recovered from condenser of steam cycle and excess heat available at the flue gases are utilized to drive cooling and desalination cycles which are optimized based on the cooling energy demands of the villas. Economic and environmental benefits of the tri-generation system in terms of cost savings and reduction in carbon emissions were analyzed. Energy efficiency of about 82%–85% is achieved by the tri-generation system compared to 50%–52% for combined cycles. Normalized carbon dioxide emission per MW·h is reduced by 51.5% by implementation of waste heat recovery tri-generation system. The tri-generation system has a payback period of 1.38 years with cumulative net present value of $66 million over the project life time.

  5. Continuous or extended cycle vs. cyclic use of combined oral contraceptives for contraception.

    Science.gov (United States)

    Edelman, A B; Gallo, M F; Jensen, J T; Nichols, M D; Schulz, K F; Grimes, D A

    2005-07-20

    The avoidance of menstruation through extended or continuous administration (greater than 28 days of active pills) of combination oral contraceptives (COCs) has gained legitimacy through its use in treating endometriosis, dysmenorrhea, and menstruation-associated symptoms. Avoidance of menstruation through continuous use of COCs for reasons of personal preference may have additional advantages to women, including improved compliance, greater satisfaction, fewer menstrual symptoms, and less menstruation-related absenteeism from work or school. To determine the differences between COCs dosed continuously (greater than 28 days of active pills) compared with traditional cyclic dosing (21 days of active pills and 7 days of placebo). Our hypothesis was that continuously administered COCs have equivalent efficacy and safety but improved bleeding profiles, amenorrhea rates, adherence, continuation, participant satisfaction, and menstrual symptoms compared with cyclic COCs. We searched computerized databases (Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, POPLINE, LILACS) for trials using continuous or extended COCs during the years 1966 to 2005. We also searched the references in review articles and publications identified for inclusion in the protocol. Investigators were contacted regarding additional references. All randomized controlled trials in any language comparing continuous (greater than 28 days of active pills) versus traditional cyclic administration (21 days of active pills and 7 days of placebo) of COCs for contraception. Titles and abstracts identified from the literature searches were assessed for potential inclusion. Data were extracted onto data collection forms and then entered into RevMan 4.2. Peto odds ratios with 95% confidence intervals were calculated for all outcomes for dichotomous outcomes. Weighted mean difference was calculated for continuous outcomes. The trials were critically appraised by examining the following factors

  6. Thermo-economic optimization of low-grade waste heat recovery in Yazd combined-cycle power plant (Iran) by a CO2 transcritical Rankine cycle

    International Nuclear Information System (INIS)

    Amini, Ali; Mirkhani, Nima; Pakjesm Pourfard, Pedram; Ashjaee, Mehdi; Khodkar, Mohammad Amin

    2015-01-01

    A transcritical CO 2 Rankine cycle is proposed for recovering low-grade waste heat of Yazd combined-cycle power plant in Iran. Each power generation module of this plant consists of two 159 MW Siemens SGT-5-2000E gas turbines and one 132 MW steam turbine. Reducing exhaust gas temperature from 150 °C to 70 °C, the plant can generate excessive power. From thermodynamics approach, it is demonstrated that by fixing the maximum temperature at 145 °C and varying the maximum pressure, the efficiency and the net power output are maximized at P max  = 185 bar. In the aforementioned operating point, about 6.3 MW is retained for the selected power plant with a nominal 450 MW of power generation. A more actual case considering thermodynamic losses and economic considerations is then investigated. Genetic algorithm is implanted to conduct a parametric optimization to maximize the benefit-cost ratio which is defined on the basis of total bare module cost and net power output. The results indicate that the cycle costs are more influenced by the maximum pressure rather than the maximum temperature. Through this parametric optimization, the CO 2 cycle can produce about 4.04 MW. This is about 0.9% of the plant capacity and increases the total efficiency about 0.4%. - Highlights: • CO 2 transcritical Rankine cycle is used to recover heat in Yazd 450 MW power plant. • The cycle behavior is examined as its maximum temperature and maximum pressure vary. • 6.3 MW could be retained for the plant on the basis of ideal thermodynamic behavior. • Thermo-economic optimization is conducted subject to actual operating conditions. • 4.04 MW is recovered considering the actual thermo-economic conditions

  7. Wabash Valley Integrated Gasification Combined Cycle, Coal to Fischer Tropsch Jet Fuel Conversion Study

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Jayesh [Lummus Technology Inc., Bloomfield, NJ (United States); Hess, Fernando [Lummus Technology Inc., Bloomfield, NJ (United States); Horzen, Wessel van [Lummus Technology Inc., Bloomfield, NJ (United States); Williams, Daniel [Lummus Technology Inc., Bloomfield, NJ (United States); Peevor, Andy [JM Davy, London (United Kingdom); Dyer, Andy [JM Davy, London (United Kingdom); Frankel, Louis [Canonsburgh, PA (United States)

    2016-06-01

    This reports examines the feasibility of converting the existing Wabash Integrated Gasification Combined Cycle (IGCC) plant into a liquid fuel facility, with the goal of maximizing jet fuel production. The fuels produced are required to be in compliance with Section 526 of the Energy Independence and Security Act of 2007 (EISA 2007 §526) lifecycle greenhouse gas (GHG) emissions requirements, so lifecycle GHG emissions from the fuel must be equal to or better than conventional fuels. Retrofitting an existing gasification facility reduces the technical risk and capital costs associated with a coal to liquids project, leading to a higher probability of implementation and more competitive liquid fuel prices. The existing combustion turbine will continue to operate on low cost natural gas and low carbon fuel gas from the gasification facility. The gasification technology utilized at Wabash is the E-Gas™ Technology and has been in commercial operation since 1995. In order to minimize capital costs, the study maximizes reuse of existing equipment with minimal modifications. Plant data and process models were used to develop process data for downstream units. Process modeling was utilized for the syngas conditioning, acid gas removal, CO2 compression and utility units. Syngas conversion to Fischer Tropsch (FT) liquids and upgrading of the liquids was modeled and designed by Johnson Matthey Davy Technologies (JM Davy). In order to maintain the GHG emission profile below that of conventional fuels, the CO2 from the process must be captured and exported for sequestration or enhanced oil recovery. In addition the power utilized for the plant’s auxiliary loads had to be supplied by a low carbon fuel source. Since the process produces a fuel gas with sufficient energy content to power the plant’s loads, this fuel gas was converted to hydrogen and exported to the existing gas turbine for low carbon power production. Utilizing low carbon fuel gas and

  8. Effects of carbohydrate combined with caffeine on repeated sprint cycling and agility performance in female athletes

    Science.gov (United States)

    2014-01-01

    Background Caffeine (CAF) has been shown to improve performance during early phase of repeated sprint exercise; however some studies show that CAF also increases the magnitude of physical stress represented by augmented blood lactate, glucose, and cortisol concentrations during latter phase of repeated sprint exercise. No studies have investigated the efficacy of combined carbohydrate (CHO) and CAF consumption during repeated sprint exercise (RSE) in female athletes. Thus, the purpose of this study was to investigate the effects of CAF with CHO supplementation on RSE and agility. Methods Eleven female athletes completed four experimental trials performed 7 d apart in a double-blind, randomized, and counter-balanced crossover design. Treatments included CAF + PLA (placebo), CAF + CHO, PLA + CHO, and PLA + PLA. Participants ingested capsules containing 6 mg · kg−1 of CAF or PLA 60-min prior to RSE, and 0.8 g · kg−1 of CHO solution or PLA immediately before the RSE, which consisted of ten sets of 5 × 4-s sprints on the cycle ergometer with 20-s active recovery. The agility T-test (AT-test) was performed before and after the RSE. Blood samples were acquired to assess glucose, lactate, testosterone, and cortisol. Results During Set 6 of RSE, peak power and mean power were significantly higher in PLA + CHO than those in CAF + PLA and PLA + PLA, respectively (p  .05). Blood lactate and glucose concentrations were significantly higher under CAF + CHO, CAF + PLA, and PLA + CHO versus PLA + PLA (p  .05). Conclusions Findings indicate that CAF + PLA or CAF + CHO ingestion did not improve repeated sprint performance with short rest intervals or agility. However, CHO ingested immediately prior to exercise provided a small but significant benefit on RSE performance in female athletes. PMID:24855458

  9. Effects of carbohydrate combined with caffeine on repeated sprint cycling and agility performance in female athletes.

    Science.gov (United States)

    Lee, Chia-Lun; Cheng, Ching-Feng; Astorino, Todd A; Lee, Chia-Jung; Huang, Hsin-Wei; Chang, Wen-Dien

    2014-01-01

    Caffeine (CAF) has been shown to improve performance during early phase of repeated sprint exercise; however some studies show that CAF also increases the magnitude of physical stress represented by augmented blood lactate, glucose, and cortisol concentrations during latter phase of repeated sprint exercise. No studies have investigated the efficacy of combined carbohydrate (CHO) and CAF consumption during repeated sprint exercise (RSE) in female athletes. Thus, the purpose of this study was to investigate the effects of CAF with CHO supplementation on RSE and agility. Eleven female athletes completed four experimental trials performed 7 d apart in a double-blind, randomized, and counter-balanced crossover design. Treatments included CAF + PLA (placebo), CAF + CHO, PLA + CHO, and PLA + PLA. Participants ingested capsules containing 6 mg · kg(-1) of CAF or PLA 60-min prior to RSE, and 0.8 g · kg(-1) of CHO solution or PLA immediately before the RSE, which consisted of ten sets of 5 × 4-s sprints on the cycle ergometer with 20-s active recovery. The agility T-test (AT-test) was performed before and after the RSE. Blood samples were acquired to assess glucose, lactate, testosterone, and cortisol. During Set 6 of RSE, peak power and mean power were significantly higher in PLA + CHO than those in CAF + PLA and PLA + PLA, respectively (p  .05). Blood lactate and glucose concentrations were significantly higher under CAF + CHO, CAF + PLA, and PLA + CHO versus PLA + PLA (p  .05). Findings indicate that CAF + PLA or CAF + CHO ingestion did not improve repeated sprint performance with short rest intervals or agility. However, CHO ingested immediately prior to exercise provided a small but significant benefit on RSE performance in female athletes.

  10. A simple model for the earthquake cycle combining self-organized complexity with critical point behavior

    Directory of Open Access Journals (Sweden)

    W. I. Newman

    2002-01-01

    Full Text Available We have studied a hybrid model combining the forest-fire model with the site-percolation model in order to better understand the earthquake cycle. We consider a square array of sites. At each time step, a "tree" is dropped on a randomly chosen site and is planted if the site is unoccupied. When a cluster of "trees" spans the site (a percolating cluster, all the trees in the cluster are removed ("burned" in a "fire." The removal of the cluster is analogous to a characteristic earthquake and planting "trees" is analogous to increasing the regional stress. The clusters are analogous to the metastable regions of a fault over which an earthquake rupture can propagate once triggered. We find that the frequency-area statistics of the metastable regions are power-law with a negative exponent of two (as in the forest-fire model. This is analogous to the Gutenberg-Richter distribution of seismicity. This "self-organized critical behavior" can be explained in terms of an inverse cascade of clusters. Small clusters of "trees" coalesce to form larger clusters. Individual trees move from small to larger clusters until they are destroyed. This inverse cascade of clusters is self-similar and the power-law distribution of cluster sizes has been shown to have an exponent of two. We have quantified the forecasting of the spanning fires using error diagrams. The assumption that "fires" (earthquakes are quasi-periodic has moderate predictability. The density of trees gives an improved degree of predictability, while the size of the largest cluster of trees provides a substantial improvement in forecasting a "fire."

  11. Simulation of a solar assisted combined heat pump – Organic rankine cycle system

    International Nuclear Information System (INIS)

    Schimpf, Stefan; Span, Roland

    2015-01-01

    Highlights: • Addition of an ORC to a solar thermal and ground source heat pump system. • Reverse operation of the scroll compressor in ORC mode. • Annual simulations for application in a single-family house at three locations. • By introducing the ORC the net electricity demand is reduced by 1–9%. • Over the lifetime of the system savings can cover additional investments. - Abstract: A novel solar thermal and ground source heat pump system that harnesses the excess heat of the collectors during summer by an Organic Rankine Cycle (ORC) is simulated. For the ORC the heat pump process is reversed. In this case the scroll compressor of the heat pump runs as a scroll expander and the working fluid is condensed in the ground heat exchanger. Compared to a conventional solar thermal system the only additional investments for the combined system are a pump, valves and upgraded controls. The goal of the study is to simulate and optimize such a system. A brief overview of the applied models and the evolutionary algorithm for the optimization is given. A system with 12 m 2 of flat plate collectors installed in a single family house is simulated for the locations Ankara, Denver and Bochum. The ORC benefits add up to 20–140 kW h/a, which reduces the net electricity demand of the system by 1–9%. Overall 180–520 € are saved over a period of 20 years, which can be enough to cover the additional investments

  12. Recovery of flue gas energy in heat-integrated gasification combined cycle (IGCC) power plants using the contact economizer system

    CSIR Research Space (South Africa)

    Madzivhandila, VA

    2011-03-01

    Full Text Available (flue gas) stream of a heat-integrated gasification combined cycle (IGCC) design of the Elcogas plant adopted from previous studies. The underlying support for this idea was the direct relationship between efficiency of the IGCC and the boiler feedwater...

  13. Fuzzy Activity Based Life Cycle Costing For Repairable Equipment

    Directory of Open Access Journals (Sweden)

    Mulubrhan Freselam

    2016-01-01

    Full Text Available Life-cycle cost (LCC is the much known method used for decision making that considers all costs in the life of a system or equipment. Predicting LCCs is fraught with potential errors, owing to the uncertainty in future events, future costs, interest rates, and even hidden costs. These uncertainties have a direct impact on the decision making. Activity based LCC is used to identify the activities and cost drivers in acquisition, operation and maintenance phase. This activity based LCC is integrated with fuzzy set theory and interval mathematics to model these uncertainties. Day–Stout–Warren (DSW algorithm and the vertex method are then used to evaluate competing alternatives. A case of two pumps (Pump A and Pump B are taken and their LCC is analysed using the developed model. The equivalent annual cost of Pump B is greater than Pump A, which leads the decision maker to choose Pump A over Pump B.

  14. Holistic energy system modeling combining multi-objective optimization and life cycle assessment

    Science.gov (United States)

    Rauner, Sebastian; Budzinski, Maik

    2017-12-01

    Making the global energy system more sustainable has emerged as a major societal concern and policy objective. This transition comes with various challenges and opportunities for a sustainable evolution affecting most of the UN’s Sustainable Development Goals. We therefore propose broadening the current metrics for sustainability in the energy system modeling field by using industrial ecology techniques to account for a conclusive set of indicators. This is pursued by including a life cycle based sustainability assessment into an energy system model considering all relevant products and processes of the global supply chain. We identify three pronounced features: (i) the low-hanging fruit of impact mitigation requiring manageable economic effort; (ii) embodied emissions of renewables cause increasing spatial redistribution of impact from direct emissions, the place of burning fuel, to indirect emissions, the location of the energy infrastructure production; (iii) certain impact categories, in which more overall sustainable systems perform worse than the cost minimal system, require a closer look. In essence, this study makes the case for future energy system modeling to include the increasingly important global supply chain and broaden the metrics of sustainability further than cost and climate change relevant emissions.

  15. Hybrid life-cycle assessment of natural gas based fuel chains for transportation.

    Science.gov (United States)

    Strømman, Anders Hammer; Solli, Christian; Hertwich, Edgar G

    2006-04-15

    This research compares the use of natural gas, methanol, and hydrogen as transportation fuels. These three fuel chains start with the extraction and processing of natural gas in the Norwegian North Sea and end with final use in Central Europe. The end use is passenger transportation with a sub-compact car that has an internal combustion engine for the natural gas case and a fuel cell for the methanol and hydrogen cases. The life cycle assessment is performed by combining a process based life-cycle inventory with economic input-output data. The analysis shows that the potential climate impacts are lowest for the hydrogen fuel scenario with CO2 deposition. The hydrogen fuel chain scenario has no significant environmental disadvantage compared to the other fuel chains. Detailed analysis shows that the construction of the car contributes significantly to most impact categories. Finally, it is shown how the application of a hybrid inventory model ensures a more complete inventory description compared to standard process-based life-cycle assessment. This is particularly significant for car construction which would have been significantly underestimated in this study using standard process life-cycle assessment alone.

  16. Gas-steam combined cycles for power generation: Current state-of-the-art and future prospects

    International Nuclear Information System (INIS)

    Macchi, E.; Chiesa, P.; Consonni, S.; Lozza, G.

    1992-01-01

    The first part of this paper points out the many factors which, after years of stagnation in the electric power industry, are giving rise to a true revolution in power generation engineering: the passing from closed cycles, using steam as the working fluid and energy sources external to the power cycle, to the use of open cycles, in which the primary energy source, in the form of a fuel, is directly immersed in the working fluid of the engine. Attention is given to the advantages in terms of energy and cost savings, greater flexibility in energy policy options and pollution abatement which are now being afforded through the use of gas turbines with combined gas-steam cycles. The second part of the paper deals with an assessment of the current state-of-the-art of the technology relative to these innovative power systems. The assessment is followed by a review of foreseen developments in combined cycle system design, choice of construction materials, type of cooling systems, operating temperatures and performance capabilities

  17. Exergoenvironmental optimization of Heat Recovery Steam Generators in combined cycle power plant through energy and exergy analysis

    International Nuclear Information System (INIS)

    Kaviri, Abdolsaeid Ganjeh; Jaafar, Mohammad Nazri Mohd.; Lazim, Tholudin Mat; Barzegaravval, Hassan

    2013-01-01

    Highlights: ► Comprehensive thermodynamic modeling of a heat recovery steam generator used in CCPP. ► To conduct exergy analysis to find the location of reversibility. ► To increase the system performance using optimization. ► Better performance assessment of the system. - Abstract: Combined cycle power plants (CCPPs) are preferred technology for electricity generation due to less emission and high efficiency. These cycles are made of a gas turbine, a steam turbine and Heat Recovery Steam Generator (HRSG). In the present research study, a combined cycle power plant with dual pressure and supplementary firing is selected. The optimum design procedure included designing objective function, exergy destruction per unit of inlet gas to the HRSG subject to a list of constraints. The design parameters (design variables) were drum pressure and pinch temperature difference as well as steam mass flow of HRSG high and low pressure levels. The influence of HRSG inlet gas temperature on the steam cycle efficiency is discussed. The result show increasing HRSG inlet gas temperature until 650 °C leads to increase the thermal efficiency and exergy efficiency of the cycle and after that has less improvement and start to decrease them. And also from the exergy analysis of each part of HRSG, it is cleared that the HP-EV and 2st HP-SH have the most exergy destruction respectively. In other hand, effects of HRSG inlet gas temperature on SI (sustainability index) and CO 2 emission are considered

  18. Thorium-based fuel cycles: Reassessment of fuel economics and proliferation risk

    Energy Technology Data Exchange (ETDEWEB)

    Serfontein, Dawid E., E-mail: Dawid.Serfontein@nwu.ac.za [Senior Lecturer at the School of Mechanical and Nuclear Engineering, North West University (PUK-Campus), PRIVATE BAG X6001, Internal Post Box 360, Potchefstroom 2520 (South Africa); Mulder, Eben J. [Professor at the School of Mechanical and Nuclear Engineering, North West University (South Africa)

    2014-05-01

    At current consumption and current prices, the proven reserves for natural uranium will last only about 100 years. However, the more abundant thorium, burned in breeder reactors, such as large High Temperature Gas-Cooled Reactors, and followed by chemical reprocessing of the spent fuel, could stretch the 100 years for uranium supply to 15,000 years. Thorium-based fuel cycles are also viewed as more proliferation resistant compared to uranium. However, several barriers to entry caused all countries, except India and Russia, to abandon their short term plans for thorium reactor projects, in favour of uranium/plutonium fuel cycles. In this article, based on the theory of resonance integrals and original analysis of fast fission cross sections, the breeding potential of {sup 232}Th is compared to that of {sup 238}U. From a review of the literature, the fuel economy of thorium-based fuel cycles is compared to that of natural uranium-based cycles. This is combined with a technical assessment of the proliferation resistance of thorium-based fuel cycles, based on a review of the literature. Natural uranium is currently so cheap that it contributes only about 10% of the cost of nuclear electricity. Chemical reprocessing is also very expensive. Therefore conservation of natural uranium by means of the introduction of thorium into the fuel is not yet cost effective and will only break even once the price of natural uranium were to increase from the current level of about $70/pound yellow cake to above about $200/pound. However, since fuel costs constitutes only a small fraction of the total cost of nuclear electricity, employing reprocessing in a thorium cycle, for the sake of its strategic benefits, may still be a financially viable option. The most important source of the proliferation resistance of {sup 232}Th/{sup 233}U fuel cycles is denaturisation of the {sup 233}U in the spent fuel by {sup 232}U, for which the highly radioactive decay chain potentially poses a large

  19. Combination of ascorbate/epigallocatechin-3-gallate/gemcitabine synergistically induces cell cycle deregulation and apoptosis in mesothelioma cells

    Energy Technology Data Exchange (ETDEWEB)

    Martinotti, Simona [Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale “Amedeo Avogadro”, viale T. Michel 11, 15121 Alessandria (Italy); Ranzato, Elia, E-mail: ranzato@unipmn.it [Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale “Amedeo Avogadro”, viale T. Michel 11, 15121 Alessandria (Italy); Parodi, Monica [IRCCS A.O.U. S. Martino-IST, Istituto Nazionale per la Ricerca sul Cancro, 16132 Genova (Italy); DI.ME.S., Università degli Studi di Genova, Via L. Alberti 2, 16132 Genova (Italy); Vitale, Massimo [IRCCS A.O.U. S. Martino-IST, Istituto Nazionale per la Ricerca sul Cancro, 16132 Genova (Italy); Burlando, Bruno [Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale “Amedeo Avogadro”, viale T. Michel 11, 15121 Alessandria (Italy)

    2014-01-01

    Malignant mesothelioma (MMe) is a poor-prognosis tumor in need of innovative therapies. In a previous in vivo study, we showed synergistic anti-MMe properties of the ascorbate/epigallocatechin-3-gallate/gemcitabine combination. We have now focused on the mechanism of action, showing the induction of apoptosis and cell cycle arrest through measurements of caspase 3, intracellular Ca{sup 2+}, annexin V, and DNA content. StellArray™ PCR technology and Western immunoblotting revealed DAPK2-dependent apoptosis, upregulation of cell cycle promoters, downregulation of cell cycle checkpoints and repression of NFκB expression. The complex of data indicates that the mixture is synergistic in inducing cell cycle deregulation and non-inflammatory apoptosis, suggesting its possible use in MMe treatment. - Highlights: • Ascorbate/epigallocathechin-gallate/gemcitabine has been tested on mesothelioma cells • A synergistic mechanism has been shown for cell cycle arrest and apoptosis • PCR-array analysis has revealed the de-regulation of apoptosis and cell cycle genes • Maximum upregulation has been found for the Death-Associated Protein Kinase-2 gene • Data suggest that the mixture could be used as a clinical treatment.

  20. Intertidal foraminifera (Protista) and carbon-nitrogen cycling: combined effects of temperature and diet quality

    Science.gov (United States)

    Wukovits, Julia; Enge, Annekatrin Julie; Oberrauch, Max; Watzka, Margarete; Wanek, Wolfgang; Heinz, Petra

    2017-04-01

    Benthic foraminifera (eukaryotic protists) are to a large extent acting as detrivores, feeding on microalgal detritus. Phytodetritus constitutes a main component of the intertidal carbon (C) and nitrogen (N) pool, thus making foraminifera important players in intertidal nutrient fluxes. These fluxes are strongly dependent on interactions between biotic and abiotic environmental factors, as e.g. the energetic value or the quality of phytodetritus that depends on environmental nutrient availability. Increased inorganic C concentrations in coastal water bodies (e.g. due to increased atmospheric CO2) can have a negative effect on the phytodetrital quality by increasing microalgal C:N ratios. Simultanous warming of the environment can cause increased metabolic rates of exposed heterotrophic organisms, like foraminifera. The combination of lower food quality and increased metabolic rates is supposed to cause cascading effects on organismic C cycling, potentially diminishing the role of detrivorous food as a C sink in marine food webs by increased discharge of excess C. In this study, the above described scenario was tested in laboratory feeding experiments on a common and abundant intertidal foraminiferal species (Haynesina germanica, collected in the German Wadden Sea). Two batches of artificially produced and dual isotope labeled (13C and 15N) chlorophyte detritus (1.5 gDW m-2) with different C:N ratios (5.5 and 7.6) and one batch of isotopically labelled diatom detritus (C:N 5.6) were fed under controlled conditions at three different temperatures. Results were extrapolated to the in situ abundance of live H. germanica individuals in the sampling area (sediment core data), to estimate the magnitude of the effect on an areal basis within the natural habitat. The study revealed significant, temperature induced variations in the carbon and nitrogen processing of H. germanica. The food source with an increased C:N ratio doubled the release of carbon from the H. germanica

  1. A Multiobjective Optimization Including Results of Life Cycle Assessment in Developing Biorenewables-Based Processes.

    Science.gov (United States)

    Helmdach, Daniel; Yaseneva, Polina; Heer, Parminder K; Schweidtmann, Artur M; Lapkin, Alexei A

    2017-09-22

    A decision support tool has been developed that uses global multiobjective optimization based on 1) the environmental impacts, evaluated within the framework of full life cycle assessment; and 2) process costs, evaluated by using rigorous process models. This approach is particularly useful in developing biorenewable-based energy solutions and chemicals manufacturing, for which multiple criteria must be evaluated and optimization-based decision-making processes are particularly attractive. The framework is demonstrated by using a case study of the conversion of terpenes derived from biowaste feedstocks into reactive intermediates. A two-step chemical conversion/separation sequence was implemented as a rigorous process model and combined with a life cycle model. A life cycle inventory for crude sulfate turpentine was developed, as well as a conceptual process of its separation into pure terpene feedstocks. The performed single- and multiobjective optimizations demonstrate the functionality of the optimization-based process development and illustrate the approach. The most significant advance is the ability to perform multiobjective global optimization, resulting in identification of a region of Pareto-optimal solutions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Catalyst based processes at back end of nuclear fuel cycle

    International Nuclear Information System (INIS)

    Vincent, T.

    2013-01-01

    Heterogeneous catalysts occupy a pivotal position in chemical industry. Their advanced preparation technology allows us to employ these catalysts for wide range of application. But the deployment of catalyst based radiochemical technology has to address the particular features like aggressive nitric acid media and intensive radiation fields. This put forward the rigid requirements to a choice of catalysts: high chemical and radiation stability of the catalyst and support, mechanical durability, catalytic activity and simplicity of preparation. Hydrogenation process with Pt/SiO 2 has been adopted industrially for making uranous nitrate (U 4+ ) from uranyl nitrate (U 6+ ) in PUREX process at commercial reprocessing plants. Bimetallic catalysts are being explored for the destruction of nitrates generated during nuclear fuel cycle operations

  3. A Neuron-Based Model of Sleep-Wake Cycles

    Science.gov (United States)

    Postnova, Svetlana; Peters, Achim; Braun, Hans

    2008-03-01

    In recent years it was discovered that a neuropeptide orexin/hypocretin plays a main role in sleep processes. This peptide is produced by the neurons in the lateral hypothalamus, which project to almost all brain areas. We present a computational model of sleep-wake cycles, which is based on the Hodgkin-Huxley type neurons and considers reciprocal glutaminergic projections between the lateral hypothalamus and the prefrontal cortex. Orexin is released as a neuromodulator and is required to keep the neurons firing, which corresponds to the wake state. When orexin is depleted the neurons are getting silent as observed in the sleep state. They can be reactivated by the circadian signal from the suprachiasmatic nucleus and/or external stimuli (alarm clock). Orexin projections to the thalamocortical neurons also can account for their transition from tonic firing activity during wakefulness to synchronized burst discharges during sleep.

  4. A strategy for the economic optimization of combined cycle gas turbine power plants by taking advantage of useful thermodynamic relationships

    International Nuclear Information System (INIS)

    Godoy, E.; Benz, S.J.; Scenna, N.J.

    2011-01-01

    Optimal combined cycle gas turbine power plants characterized by minimum specific annual cost values are here determined for wide ranges of market conditions as given by the relative weights of capital investment and operative costs, by means of a non-linear mathematical programming model. On the other hand, as the technical optimization allows identifying trends in the system behavior and unveiling optimization opportunities, selected functional relationships are obtained as the thermodynamic optimal values of the decision variables are systematically linked to the ratio between the total heat transfer area and the net power production (here named as specific transfer area). A strategy for simplifying the resolution of the rigorous economic optimization problem of power plants is proposed based on the economic optima distinctive characteristics which describe the behavior of the decision variables of the power plant on its optima. Such approach results in a novel mathematical formulation shaped as a system of non-linear equations and additional constraints that is able to easily provide accurate estimations of the optimal values of the power plant design and operative variables. Research highlights: → We achieve relationships between power plants' economic and thermodynamic optima. → We achieve functionalities among thermodynamic optimal values of decision variables. → The rigorous optimization problem is reduced to a non-linear equations system. → Accurate estimations of power plants' design and operative variables are obtained.

  5. Exergy Analysis of a Syngas-Fueled Combined Cycle with Chemical-Looping Combustion and CO2 Sequestration

    Directory of Open Access Journals (Sweden)

    Álvaro Urdiales Montesino

    2016-08-01

    Full Text Available Fossil fuels are still widely used for power generation. Nevertheless, it is possible to attain a short- and medium-term substantial reduction of greenhouse gas emissions to the atmosphere through a sequestration of the CO2 produced in fuels’ oxidation. The chemical-looping combustion (CLC technique is based on a chemical intermediate agent, which gets oxidized in an air reactor and is then conducted to a separated fuel reactor, where it oxidizes the fuel in turn. Thus, the oxidation products CO2 and H2O are obtained in an output flow in which the only non-condensable gas is CO2, allowing the subsequent sequestration of CO2 without an energy penalty. Furthermore, with shrewd configurations, a lower exergy destruction in the combustion chemical transformation can be achieved. This paper focus on a second law analysis of a CLC combined cycle power plant with CO2 sequestration using syngas from coal and biomass gasification as fuel. The key thermodynamic parameters are optimized via the exergy method. The proposed power plant configuration is compared with a similar gas turbine system with a conventional combustion, finding a notable increase of the power plant efficiency. Furthermore, the influence of syngas composition on the results is investigated by considering different H2-content fuels.

  6. Predictive control strategy of a gas turbine for improvement of combined cycle power plant dynamic performance and efficiency.

    Science.gov (United States)

    Mohamed, Omar; Wang, Jihong; Khalil, Ashraf; Limhabrash, Marwan

    2016-01-01

    This paper presents a novel strategy for implementing model predictive control (MPC) to a large gas turbine power plant as a part of our research progress in order to improve plant thermal efficiency and load-frequency control performance. A generalized state space model for a large gas turbine covering the whole steady operational range is designed according to subspace identification method with closed loop data as input to the identification algorithm. Then the model is used in developing a MPC and integrated into the plant existing control strategy. The strategy principle is based on feeding the reference signals of the pilot valve, natural gas valve, and the compressor pressure ratio controller with the optimized decisions given by the MPC instead of direct application of the control signals. If the set points for the compressor controller and turbine valves are sent in a timely manner, there will be more kinetic energy in the plant to release faster responses on the output and the overall system efficiency is improved. Simulation results have illustrated the feasibility of the proposed application that has achieved significant improvement in the frequency variations and load following capability which are also translated to be improvements in the overall combined cycle thermal efficiency of around 1.1 % compared to the existing one.

  7. Gender-based differences and menstrual cycle-related changes in specific diseases: implications for pharmacotherapy.

    Science.gov (United States)

    Ensom, M H

    2000-05-01

    Pharmacists should be aware of gender-based differences and menstrual cycle-related changes in six diseases: asthma, arthritis, migraine, diabetes, depression, and epilepsy. In general, women report symptoms of physical illness at higher rates, visit physicians more frequently, and make greater use of other health care services than men. Whereas reasons for these gender differences are not fully clear, a combination of biologic, physiologic, social, behavioral, psychologic, and cultural factors most likely contributes. A significant percentage of women with asthma, arthritis, migraine, diabetes, depression, or epilepsy experience worsening of their disease premenstrually. The mechanism is unknown, but is speculated to be multifactorial because of many endogenous and exogenous modulators and mediators of each disease. As part of general therapy for cycle-related exacerbations of any one of these disorders, patients should be encouraged to use a menstrual calendar to track signs and symptoms for two to three cycles; if cyclic trends are identified, the women should anticipate exacerbations and avoid triggering factors. Cyclic modulation with pharmacotherapy may be attempted. If unsuccessful, a trial of medical ovulation suppression with a gonadotropin-releasing hormone (GnRH) analog may be warranted. If that is successful, continuous therapy with a GnRH analog and steroid add-back therapy or less expensive alternatives may be effective. If pharmacotherapy is impractical, hysterectomy and bilateral oophorectomy with estrogen replacement therapy is a last resort. Gender differences and menstrual cycle-related changes are important areas for clinical and mechanistic research.

  8. Cytotoxicity and cell-cycle effects of paclitaxel when used as a single agent and in combination with ionizing radiation

    International Nuclear Information System (INIS)

    Gupta, Nalin; Hu, Lily J.; Deen, Dennis F.

    1997-01-01

    Purpose: This study aimed to determine the extent of paclitaxel-induced cytotoxicity and cell-cycle perturbations when used alone and in combination with radiation in human glioma cells. Methods and Materials: The effect of paclitaxel alone on three human glioma cells lines--SF-126, U-87 MG, and U-251 MG--was assessed after 24, 48, 72, or 96 h treatment. For experiments in combination with radiation, cells were exposed to either a long (48-h) or short (8-h) duration of paclitaxel treatment prior to irradiation. Cell survival was determined by clonogenic assay. Cell cycle perturbations were assessed by using flow cytometry to measure the proportion of cells in G 1 , S, and G 2 /M phases. Results: When cells were treated with paclitaxel alone for ≥24 h, cytotoxicity increased up to a threshold dose, after which it plateaued. When treatment duration was ≤24 h, cytotoxicity was appreciably greater in U-251 MG cells than in SF-126 and U-87 MG cells. After 24 h of paclitaxel treatment, cells in plateau phase growth had increased survival compared to cells in log phase growth. In contrast, after 8 h paclitaxel treatment, mitotic cells had reduced survival compared to cells from an asynchronous population. Cell-cycle perturbations were consistent with the presence of a mitotic block after paclitaxel treatment, although changes in other cell-cycle phase fractions varied among cell lines. For experiments in combination with radiation, cytotoxicity was increased when cells were irradiated after 48 h of paclitaxel treatment but not after 8 h of treatment. Conclusion: The duration of paclitaxel treatment and the location of cells in the cell cycle modify the degree of radiation cytotoxicity. The mechanisms of paclitaxel cytotoxicity are likely to be multifactorial because varying effects are seen in different cell lines. Furthermore, it is clear that simply increasing the number of cells in G 2 /M is insufficient in itself to increase the response of cells to radiation

  9. Improving crystal size distribution by internal seeding combined cooling/antisolvent crystallization with a cooling/heating cycle

    Science.gov (United States)

    Lenka, Maheswata; Sarkar, Debasis

    2018-03-01

    This work investigates the effect of internal seeding and an initial cooling/heating cycle on the final crystal size distribution (CSD) during a combined cooling/antisolvent crystallization of L-asparagine monohydrate from it's aqueous solution using isopropyl-alcohol as antisolvent. Internal seeds were generated by one-pot addition of various amounts of antisolvent to the crystallizer. It was then followed by a cooling/heating cycle to dissolve the fines produced and thus obtain a suitable initial seed. A combined cooling/antisolvent crystallization was then followed by employing a linear cooling profile with simultaneous addition of antisolvent with a constant mass flow rate to promote the growth of the internally generated seeds. The amount of initial antisolvent influences the characteristics of the internal seeds generated and the effect of initial amount of antisolvent on the final CSD is investigated. It was found that the introduction of a single cooling/heating cycle significantly improves the reproducibility of final CSD as well as the mean size. Overall, the study indicates that the application of internal seeding with a single cooling/heating cycle for fines dissolution is an effective technique to tailor crystal size distribution.

  10. Combined cycles and cogeneration with natural gas and alternative fuels; Cicli combinati e cogenerazione con gas naturale e combustibili alternativi

    Energy Technology Data Exchange (ETDEWEB)

    Gusso, R. [Turbotecnica SpA, Florence (Italy)

    1992-12-31

    Since 1985 there has been a sharp increase world-wide in the sales of gas turbines. The main reasons for this are: the improved designs allowing better gas turbine and, thus, combined cycle efficiencies; the good fuel use indices in the the case of cogeneration; the versatility of the gas turbines even with poly-fuel plants; greatly limited exhaust emissions; and lower manufacturing costs and delivery times with respect to conventional plants. This paper after a brief discussion on the evolution in gas turbine applications in the world and in Italy, assesses their use and environmental impacts with fuels other than natural gas. The paper then reviews Italian efforts to develop power plants incorporating combined cycles and the gasification of coal, residual, and other low calorific value fuels.

  11. Combining optimization and machine learning techniques for genome-wide prediction of human cell cycle-regulated genes.

    Science.gov (United States)

    De Santis, Marianna; Rinaldi, Francesco; Falcone, Emmanuela; Lucidi, Stefano; Piaggio, Giulia; Gurtner, Aymone; Farina, Lorenzo

    2014-01-15

    The identification of cell cycle-regulated genes through the cyclicity of messenger RNAs in genome-wide studies is a difficult task due to the presence of internal and external noise in microarray data. Moreover, the analysis is also complicated by the loss of synchrony occurring in cell cycle experiments, which often results in additional background noise. To overcome these problems, here we propose the LEON (LEarning and OptimizatioN) algorithm, able to characterize the 'cyclicity degree' of a gene expression time profile using a two-step cascade procedure. The first step identifies a potentially cyclic behavior by means of a Support Vector Machine trained with a reliable set of positive and negative examples. The second step selects those genes having peak timing consistency along two cell cycles by means of a non-linear optimization technique using radial basis functions. To prove the effectiveness of our combined approach, we use recently published human fibroblasts cell cycle data and, performing in vivo experiments, we demonstrate that our computational strategy is able not only to confirm well-known cell cycle-regulated genes, but also to predict not yet identified ones. All scripts for implementation can be obtained on request.

  12. High-efficiency low LCOE combined cycles for sour gas oxy-combustion with CO[subscript 2] capture

    OpenAIRE

    Chakroun, Nadim Walid; Ghoniem, Ahmed F

    2015-01-01

    The growing concerns over global warming and carbon dioxide emissions have driven extensive research into novel ways of capturing carbon dioxide in power generation plants. In this regard, oxy-fuel combustion has been considered as a promising technology. One unconventional fuel that is considered is sour gas, which is a mixture of methane, hydrogen sulfide and carbon dioxide. In this paper, carbon dioxide is used as the dilution medium in the combustor and different combined cycle configurat...

  13. Functioning of nitric oxide cycle in gastric mucosa of rats under excessive combined intake of sodium nitrate and fluoride

    OpenAIRE

    O. Ye. Akimov; V. O. Kostenko

    2016-01-01

    In the article the function of nitric oxide (·NO) cycle in rat’s gastric mucosa was assessed under excessive combined chronic fluoride and nitrate intake during 30 days. It was estimated that general nitric oxide synthase activity (NOS) was increased during excessive sodium fluoride intake meanwhile influence on gene­ral nitrate reduction was not statistically significant, but general nitrite reduction was increased. General arginase activity decreased. Excessive sodium nitrate intake decreas...

  14. Nutrient limitation reduces land carbon uptake in simulations with a model of combined carbon, nitrogen and phosphorus cycling

    Directory of Open Access Journals (Sweden)

    D. S. Goll

    2012-09-01

    Full Text Available Terrestrial carbon (C cycle models applied for climate projections simulate a strong increase in net primary productivity (NPP due to elevated atmospheric CO2 concentration during the 21st century. These models usually neglect the limited availability of nitrogen (N and phosphorus (P, nutrients that commonly limit plant growth and soil carbon turnover. To investigate how the projected C sequestration is altered when stoichiometric constraints on C cycling are considered, we incorporated a P cycle into the land surface model JSBACH (Jena Scheme for Biosphere–Atmosphere Coupling in Hamburg, which already includes representations of coupled C and N cycles.

    The model reveals a distinct geographic pattern of P and N limitation. Under the SRES (Special Report on Emissions Scenarios A1B scenario, the accumulated land C uptake between 1860 and 2100 is 13% (particularly at high latitudes and 16% (particularly at low latitudes lower in simulations with N and P cycling, respectively, than in simulations without nutrient cycles. The combined effect of both nutrients reduces land C uptake by 25% compared to simulations without N or P cycling. Nutrient limitation in general may be biased by the model simplicity, but the ranking of limitations is robust against the parameterization and the inflexibility of stoichiometry. After 2100, increased temperature and high CO2 concentration cause a shift from N to P limitation at high latitudes, while nutrient limitation in the tropics declines. The increase in P limitation at high-latitudes is induced by a strong increase in NPP and the low P sorption capacity of soils, while a decline in tropical NPP due to high autotrophic respiration rates alleviates N and P limitations. The quantification of P limitation remains challenging. The poorly constrained processes of soil P sorption and biochemical mineralization are identified as the main uncertainties in the strength of P limitation

  15. Single and combined effects of beetroot juice and caffeine supplementation on cycling time trial performance.

    Science.gov (United States)

    Lane, Stephen C; Hawley, John A; Desbrow, Ben; Jones, Andrew M; Blackwell, James R; Ross, Megan L; Zemski, Adam J; Burke, Louise M

    2014-09-01

    Both caffeine and beetroot juice have ergogenic effects on endurance cycling performance. We investigated whether there is an additive effect of these supplements on the performance of a cycling time trial (TT) simulating the 2012 London Olympic Games course. Twelve male and 12 female competitive cyclists each completed 4 experimental trials in a double-blind Latin square design. Trials were undertaken with a caffeinated gum (CAFF) (3 mg·kg(-1) body mass (BM), 40 min prior to the TT), concentrated beetroot juice supplementation (BJ) (8.4 mmol of nitrate (NO3(-)), 2 h prior to the TT), caffeine plus beetroot juice (CAFF+BJ), or a control (CONT). Subjects completed the TT (females: 29.35 km; males: 43.83 km) on a laboratory cycle ergometer under conditions of best practice nutrition: following a carbohydrate-rich pre-event meal, with the ingestion of a carbohydrate-electrolyte drink and regular oral carbohydrate contact during the TT. Compared with CONT, power output was significantly enhanced after CAFF+BJ and CAFF (3.0% and 3.9%, respectively, p caffeine (-0.9%, p = 0.4 compared with CAFF). We conclude that caffeine (3 mg·kg(-1) BM) administered in the form of a caffeinated gum increased cycling TT performance lasting ∼50-60 min by ∼3%-4% in both males and females. Beetroot juice supplementation was not ergogenic under the conditions of this study.

  16. The Martian Water Cycle Based on 3-D Modeling

    Science.gov (United States)

    Houben, H.; Haberle, R. M.; Joshi, M. M.

    1999-01-01

    Understanding the distribution of Martian water is a major goal of the Mars Surveyor program. However, until the bulk of the data from the nominal missions of TES, PMIRR, GRS, MVACS, and the DS2 probes are available, we are bound to be in a state where much of our knowledge of the seasonal behavior of water is based on theoretical modeling. We therefore summarize the results of this modeling at the present time. The most complete calculations come from a somewhat simplified treatment of the Martian climate system which is capable of simulating many decades of weather. More elaborate meteorological models are now being applied to study of the problem. The results show a high degree of consistency with observations of aspects of the Martian water cycle made by Viking MAWD, a large number of ground-based measurements of atmospheric column water vapor, studies of Martian frosts, and the widespread occurrence of water ice clouds. Additional information is contained in the original extended abstract.

  17. Optimization of Initial Parameters and Fuel Afterburning Ratio in Heat-Recovery Boiler of Single- and Two-Loop Combined-Cycle Plant

    Directory of Open Access Journals (Sweden)

    B. V. Yakovlev

    2007-01-01

    Full Text Available An analysis of influence of initial parameters and fuel afterburning ratio on efficiency of sin­gle- and two-loop combined-cycle plant has been done in the paper.The paper contains fundamentals of combined-cycle plants initial parameters’ optimization and examples for the sets with gas turbines of various efficiency.

  18. Simulated performance of biomass gasification based combined power and refrigeration plant for community scale application

    Science.gov (United States)

    Chattopadhyay, S.; Mondal, P.; Ghosh, S.

    2016-07-01

    Thermal performance analysis and sizing of a biomass gasification based combined power and refrigeration plant (CPR) is reported in this study. The plant is capable of producing 100 kWe of electrical output while simultaneously producing a refrigeration effect, varying from 28-68 ton of refrigeration (TR). The topping gas turbine cycle is an indirectly heated all-air cycle. A combustor heat exchanger duplex (CHX) unit burns producer gas and transfer heat to air. This arrangement avoids complex gas cleaning requirements for the biomass-derived producer gas. The exhaust air of the topping GT is utilized to run a bottoming ammonia absorption refrigeration (AAR) cycle via a heat recovery steam generator (HRSG), steam produced in the HRSG supplying heat to the generator of the refrigeration cycle. Effects of major operating parameters like topping cycle pressure ratio (rp) and turbine inlet temperature (TIT) on the energetic performance of the plant are studied. Energetic performance of the plant is evaluated via energy efficiency, required biomass consumption and fuel energy savings ratio (FESR). The FESR calculation method is significant for indicating the savings in fuel of a combined power and process heat plant instead of separate plants for power and process heat. The study reveals that, topping cycle attains maximum power efficiency of 30%in pressure ratio range of 8-10. Up to a certain value of pressure ratio the required air flow rate through the GT unit decreases with increase in pressure ratio and then increases with further increase in pressure ratio. The capacity of refrigeration of the AAR unit initially decreases up to a certain value of topping GT cycle pressure ratio and then increases with further increase in pressure ratio. The FESR is found to be maximized at a pressure ratio of 9 (when TIT=1100°C), the maximum value being 53%. The FESR is higher for higher TIT. The heat exchanger sizing is also influenced by the topping cycle pressure ratio and GT-TIT.

  19. Efficient cycles for carbon capture CLC power plants based on thermally balanced redox reactors

    KAUST Repository

    Iloeje, Chukwunwike

    2015-10-01

    © 2015 Elsevier Ltd. The rotary reactor differs from most alternative chemical looping combustion (CLC) reactor designs because it maintains near-thermal equilibrium between the two stages of the redox process by thermally coupling channels undergoing oxidation and reduction. An earlier study showed that this thermal coupling between the oxidation and reduction reactors increases the efficiency by up to 2% points when implemented in a regenerative Brayton cycle. The present study extends this analysis to alternative CLC cycles with the objective of identifying optimal configurations and design tradeoffs. Results show that the increased efficiency from reactor thermal coupling applies only to cycles that are capable of exploiting the increased availability in the reduction reactor exhaust. Thus, in addition to the regenerative cycle, the combined CLC cycle and the combined-regenerative CLC cycle are suitable for integration with the rotary reactor. Parametric studies are used to compare the sensitivity of the different cycle efficiencies to parameters like pressure ratio, turbine inlet temperature, carrier-gas fraction and purge steam generation. One of the key conclusions from this analysis is that while the optimal efficiency for regenerative CLC cycle was the highest of the three (56% at 3. bars, 1200. °C), the combined-regenerative cycle offers a trade-off that combines a reasonably high efficiency (about 54% at 12. bars, 1200. °C) with much lower gas volumetric flow rate and consequently, smaller reactor size. Unlike the other two cycles, the optimal compressor pressure ratio for the regenerative cycle is weakly dependent on the design turbine inlet temperature. For the regenerative and combined regenerative cycles, steam production in the regenerator below 2× fuel flow rate improves exhaust recovery and consequently, the overall system efficiency. Also, given that the fuel side regenerator flow is unbalanced, it is more efficient to generate steam from the

  20. Formal TCA cycle description based on elementary actions

    Indian Academy of Sciences (India)

    2006-12-20

    Dec 20, 2006 ... Applied to the description of the tricarboxylic acid cycle (TCA), we show that BioΨ allows the formal integration of functional information existing in current databases and make them available for further automated analysis. In addition such a formal TCA cycle process description leads to a more accurate ...

  1. Effects of cytokine combinations on the cell cycle and early apoptosis of irradiated umbilical cord blood AC133+ cells

    International Nuclear Information System (INIS)

    Liu Yulong; Dai Hong; Jiang Zhong; Zhou Liying; Guo Xiaokui; Zhou Jianying

    2005-01-01

    The cell cycle and early apoptosis of 2.5 Gy 6 MV-X ray irradiated umbilical cord blood AC133 + cells cultured with cytokine combinations (IL-3 + FL + SCF) were immunolabelled and analyzed by flow cytometry at d 0, 1, 2, 3 and 7. The result of flow cytometry analysis showed that majority of irradiated umbilical cord blood AC133 + cells were in G 0 /G 1 phase of the cell cycle at d 0. Under the influence of cytokine combinations (IL-3 + FL + SCF), nearly 50% of cells were in S phase on 3rd day. AC133 + cells irradiated were in vitro incubated in the medium without cytokines, nearly all cells died by apoptosis. However, when we incubated cells with cytokine combinations (IL-3 + FL + SCF), (38.0 ± 6.8)% of cells were saved from apoptosis at d 2. The more percent of saved AC133 + cells became to proliferate with the extension of culture. In short, cytokine combinations (IL-3 + FL + SCF) could have a key role to protect irradiated cells and partially avoid induction of apoptosis by ionizing radiation in hematopoietics stem/progenitor cells. (authors)

  2. Analysis of the Properties of Working Substances for the Organic Rankine Cycle based Database “REFPROP”

    Directory of Open Access Journals (Sweden)

    Galashov Nikolay

    2016-01-01

    Full Text Available The object of the study are substances that are used as a working fluid in systems operating on the basis of an organic Rankine cycle. The purpose of research is to find substances with the best thermodynamic, thermal and environmental properties. Research conducted on the basis of the analysis of thermodynamic and thermal properties of substances from the base “REFPROP” and with the help of numerical simulation of combined-cycle plant utilization triple cycle, where the lower cycle is an organic Rankine cycle. Base “REFPROP” describes and allows to calculate the thermodynamic and thermophysical parameters of most of the main substances used in production processes. On the basis of scientific publications on the use of working fluids in an organic Rankine cycle analysis were selected ozone-friendly low-boiling substances: ammonia, butane, pentane and Freon: R134a, R152a, R236fa and R245fa. For these substances have been identified and tabulated molecular weight, temperature of the triple point, boiling point, at atmospheric pressure, the parameters of the critical point, the value of the derivative of the temperature on the entropy of the saturated vapor line and the potential ozone depletion and global warming. It was also identified and tabulated thermodynamic and thermophysical parameters of the steam and liquid substances in a state of saturation at a temperature of 15 °C. This temperature is adopted as the minimum temperature of heat removal in the Rankine cycle when working on the water. Studies have shown that the best thermodynamic, thermal and environmental properties of the considered substances are pentane, butane and R245fa. For a more thorough analysis based on a gas turbine plant NK-36ST it has developed a mathematical model of combined cycle gas turbine (CCGT triple cycle, where the lower cycle is an organic Rankine cycle, and is used as the air cooler condenser. Air condenser allows stating material at a temperature

  3. Solving Fatigue Problems for Reversed and Repeated Biaxial Combined Stress Cycles

    Science.gov (United States)

    Pogrebnyak, A. D.

    2016-05-01

    An approach to the analysis of the limit state and the fatigue life of simplest structural members subject to a combination of inphase cyclic tension/compression and cyclic torsion or a combination of cyclic bending and cyclic torsion is proposed. The solution is constructed using a limit-state model that relates the fatigue strengths in terms of a power transcendental function. The calculated results are validated experimentally for solid prismatic rods and thin-walled tubes subject to fatigue failure

  4. Fossil fuel savings, carbon emission reduction and economic attractiveness of medium-scale integrated biomass gasification combined cycle cogeneration plants

    Directory of Open Access Journals (Sweden)

    Kalina Jacek

    2012-01-01

    Full Text Available The paper theoretically investigates the system made up of fluidized bed gasifier, SGT-100 gas turbine and bottoming steam cycle. Different configurations of the combined cycle plant are examined. A comparison is made between systems with producer gas (PG and natural gas (NG fired turbine. Supplementary firing of the PG in a heat recovery steam generator is also taken into account. The performance of the gas turbine is investigated using in-house built Engineering Equation Solver model. Steam cycle is modeled using GateCycleTM simulation software. The results are compared in terms of electric energy generation efficiency, CO2 emission and fossil fuel energy savings. Finally there is performed an economic analysis of a sample project. The results show relatively good performance in the both alternative configurations at different rates of supplementary firing. Furthermore, positive values of economic indices were obtained. [Acknowledgements. This work was carried out within the frame of research project no. N N513 004036, titled: Analysis and optimization of distributed energy conversion plants integrated with gasification of biomass. The project is financed by the Polish Ministry of Science.

  5. Combined Life Cycle Assessment and Life Cycle Costing in the Eco-Care-Matrix: A case study on the performance of a modernized manufacturing system for glass containers

    DEFF Research Database (Denmark)

    Auer, Johannes; Bey, Niki; Schäfer, Johannes-Marius

    2017-01-01

    are the motors due to their material composition, number and mass. The use stage was subsequently recognized as the dominant life cycle stage with Global Warming Potential (GWP) as the leading indicator, due to the long service life (20 years) and the corresponding energy consumption. The analysis of a produced...... glass bottle's GWP showed that it was reduced by about 40% through optimizing the production system. The LCC showed that the modernization pays off after about five years of service life and that the decision for making an Investment should not only be based on the required capital expenditure (CAPEX...

  6. Dual capillary tube / heat exchanger in combination with cycle priming for reducing charge migration

    Science.gov (United States)

    Gomes, Alberto Regio; Kuehl, Steven J.; Litch, Andrew D.; Wu, Guolian

    2017-07-04

    A refrigerator appliance including a multi-capacity compressor and a refrigerant circuit with two conduits and pressure reducing devices arranged in parallel between an evaporator and a condenser. Refrigerant can flow through one, both or none of the conduits and pressure reducing devices. The appliance also has a heat exchanger in contact with either one pressure reducing device, or one conduit between the pressure reducing device and the valve system. The appliance also includes a controller for priming the compressor above a nominal capacity for a predetermined or calculated duration at the beginning of an ON-cycle.

  7. Limit Cycle Prediction Based on Evolutionary Multiobjective Formulation

    Directory of Open Access Journals (Sweden)

    M. Katebi

    2009-01-01

    In the second part, SIDF is extended to the class of nonlinear multiinput multioutput (MIMO systems containing separable nonlinear elements of any general form. In both cases linearized harmonic balance equations are derived and the search for a limit cycle is formulated as a multiobjective problem. Multiobjective genetic algorithm (MOGA is utilized to search the space of parameters of theoretically possible limit cycle operations. Case studies are presented to demonstrate the effectiveness of the proposed approach.

  8. Market-Based and System-Wide Fuel Cycle Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Paul Philip Hood [Univ. of Wisconsin, Madison, WI (United States); Scopatz, Anthony [Univ. of South Carolina, Columbia, SC (United States); Gidden, Matthew [Univ. of Wisconsin, Madison, WI (United States); Carlsen, Robert [Univ. of Wisconsin, Madison, WI (United States); Mouginot, Baptiste [Univ. of Wisconsin, Madison, WI (United States); Flanagan, Robert [Univ. of South Carolina, Columbia, SC (United States)

    2017-06-13

    This work introduces automated optimization into fuel cycle simulations in the Cyclus platform. This includes system-level optimizations, seeking a deployment plan that optimizes the performance over the entire transition, and market-level optimization, seeking an optimal set of material trades at each time step. These concepts were introduced in a way that preserves the flexibility of the Cyclus fuel cycle framework, one of its most important design principles.

  9. Market-Based and System-Wide Fuel Cycle Optimization

    International Nuclear Information System (INIS)

    Wilson, Paul Philip Hood; Scopatz, Anthony; Gidden, Matthew; Carlsen, Robert; Mouginot, Baptiste; Flanagan, Robert

    2017-01-01

    This work introduces automated optimization into fuel cycle simulations in the Cyclus platform. This includes system-level optimizations, seeking a deployment plan that optimizes the performance over the entire transition, and market-level optimization, seeking an optimal set of material trades at each time step. These concepts were introduced in a way that preserves the flexibility of the Cyclus fuel cycle framework, one of its most important design principles.

  10. Dynamic performance of a combined gas turbine and air bottoming cycle plant for off-shore applications

    DEFF Research Database (Denmark)

    Benato, Alberto; Pierobon, Leonardo; Haglind, Fredrik

    2014-01-01

    to improve the plant performance, a bottoming cycle unit can be added to the gas turbine topping module, thus constituting a combined cycle plant. This paper aims at developing and testing the numerical model simulating the part-load and dynamic behavior of a novel power system, composed of two gas turbines......-load with the mass flow rate. Thermodynamic variables and dynamic metrics, such as the rise time and the frequency undershooting/ overshooting, are predicted. Considering a load ramp of 0.5 MW/s, an undershooting of 4.9% and an overshooting of 3.0% are estimated. The rise time is approximately 30 s. Moreover......, findings suggest that decreasing the core weight of the recuperator leads to limiting the frequency fluctuations, thus minimizing the risk of failure of the power system....

  11. Combined climate and carbon-cycle effects of large-scale deforestation.

    Science.gov (United States)

    Bala, G; Caldeira, K; Wickett, M; Phillips, T J; Lobell, D B; Delire, C; Mirin, A

    2007-04-17

    The prevention of deforestation and promotion of afforestation have often been cited as strategies to slow global warming. Deforestation releases CO(2) to the atmosphere, which exerts a warming influence on Earth's climate. However, biophysical effects of deforestation, which include changes in land surface albedo, evapotranspiration, and cloud cover also affect climate. Here we present results from several large-scale deforestation experiments performed with a three-dimensional coupled global carbon-cycle and climate model. These simulations were performed by using a fully three-dimensional model representing physical and biogeochemical interactions among land, atmosphere, and ocean. We find that global-scale deforestation has a net cooling influence on Earth's climate, because the warming carbon-cycle effects of deforestation are overwhelmed by the net cooling associated with changes in albedo and evapotranspiration. Latitude-specific deforestation experiments indicate that afforestation projects in the tropics would be clearly beneficial in mitigating global-scale warming, but would be counterproductive if implemented at high latitudes and would offer only marginal benefits in temperate regions. Although these results question the efficacy of mid- and high-latitude afforestation projects for climate mitigation, forests remain environmentally valuable resources for many reasons unrelated to climate.

  12. Combination contraceptive effects on monthly cycle of plasma aldosterone, renin activity and renin substrate.

    Science.gov (United States)

    Katz, F H; Romfh, P; Smith, J A; Roper, E F; Barnes, J S

    1975-06-01

    A post-ovulatory peak of fasting supine plasma aldosterone (PA) preceded or accompanied by an increase in plasma renin activity (PRA) was previously reported. These studies have now been extended in 4 additional normal menstruating women and 4 women taking oestrogen-progestogen oral contraceptive pills (OCP), all studied daily for an entire cycle. Distinct luteal phase increases in PRA were seen in the 4 normals, with 2 also demonstrating a rise in PA. Plasma renin substrate (PRS) was usually unvarying throughout the control cycles. The women taking OCP, on the other hand, all had PA and PRA peaks that were apparent by the fourth or fifth day of taking "the pill". All 4 of the treated women had elevated PRS levels but only one woman showed an increase which preceded the elevation of PRA and PA. Plasma cortisol levels were usually above the normal range in the women taking OCP. This study thus indicates that factors other than oestrogen-induced increased substrate production may be responsible for the PRA and PA rise during OCP treatment. Such factors might be the natri-uretic effects of oestrogens and progestogens or a direct effect on renin secretion by one of these steroids.

  13. Development of a thermal scheme for a cogeneration combined-cycle unit with an SVBR-100 reactor

    Science.gov (United States)

    Kasilov, V. F.; Dudolin, A. A.; Krasheninnikov, S. M.

    2017-02-01

    At present, the prospects for development of district heating that can increase the effectiveness of nuclear power stations (NPS), cut down their payback period, and improve protection of the environment against harmful emissions are being examined in the nuclear power industry of Russia. It is noted that the efficiency of nuclear cogeneration power stations (NCPS) is drastically affected by the expenses for heat networks and heat losses during transportation of a heat carrier through them, since NPSs are usually located far away from urban area boundaries as required for radiation safety of the population. The prospects for using cogeneration power units with small or medium power reactors at NPSs, including combined-cycle units and their performance indices, are described. The developed thermal scheme of a cogeneration combined-cycle unit (CCU) with an SBVR-100 nuclear reactor (NCCU) is presented. This NCCU should use a GE 6FA gasturbine unit (GTU) and a steam-turbine unit (STU) with a two-stage district heating plant. Saturated steam from the nuclear reactor is superheated in a heat-recovery steam generator (HRSG) to 560-580°C so that a separator-superheater can be excluded from the thermal cycle of the turbine unit. In addition, supplemental fuel firing in HRSG is examined. NCCU effectiveness indices are given as a function of the ambient air temperature. Results of calculations of the thermal cycle performance under condensing operating conditions indicate that the gross electric efficiency η el NCCU gr of = 48% and N el NCCU gr = 345 MW can be achieved. This efficiency is at maximum for NCCU with an SVBR-100 reactor. The conclusion is made that the cost of NCCU installed kW should be estimated, and the issue associated with NCCUs siting with reference to urban area boundaries must be solved.

  14. Exergic, economic and environmental impacts of natural gas and diesel in operation of combined cycle power plants

    International Nuclear Information System (INIS)

    Mohammadi Khoshkar Vandani, Amin; Joda, Fatemeh; Bozorgmehry Boozarjomehry, Ramin

    2016-01-01

    Highlights: • Investigating the effect of natural gas and diesel on the power plant performance. • Exergy, economic and environmental evaluation of a combined cycle power plant. • Using life cycle assessment (LCA) to perform the environmental evaluation. • Optimizing the power plant in terms of exergy and economic. • Better performance of natural gas with respect to diesel. - Abstract: Combined cycle power plants (CCPPs) play an important role in electricity production throughout the world. Their energy efficiency is relatively high and their production rates of greenhouse gases are considerably low. In a country like Iran with huge oil and gas resources, most CCPP’s use natural gas as primary fuel and diesel as secondary fuel. In this study, effect of using diesel instead of natural gas for a selected power plant will be investigated in terms of exergy, economic and environmental impacts. The environmental evaluation is performed using life cycle assessment (LCA). In the second step, the operation of the plant will be optimized using exergy and economic objective functions. The results show that the exergy efficiency of the plant with natural gas as fuel is equal to 43.11%, while this efficiency with diesel will be 42.03%. Furthermore, the annual cost of plant using diesel is twice as that of plant using natural gas. Finally, diesel utilization leads to more contaminants production. Thus, environmental effects of diesel are much higher than that of natural gas. The optimization results demonstrate that in case of natural gas, exergy efficiency and annual cost of the power plant improve 2.34% and 4.99%, respectively. While these improvements for diesel are 2.36% and 1.97%.

  15. Utilization of waste heat from GTMHR for hydrogen generation via combination of organic Rankine cycles and PEM electrolysis

    International Nuclear Information System (INIS)

    Nami, Hossein; Mohammadkhani, Farzad; Ranjbar, Faramarz

    2016-01-01

    Highlights: • An integrated system is proposed to produce power and hydrogen. • The effects of some decision parameters on the produced hydrogen have investigated. • An optimization is performed using Search Direct Method. - Abstract: Energy and exergy analyses are carried out for hydrogen production via Gas Turbine Modular Helium Reactor/Organic Rankine Cycle (GTMHR/ORC) system coupled with a proton exchange membrane electrolyzer. A comprehensive parametric study is performed and the effects of some significant variables as compressor pressure ratio, turbine inlet temperature, evaporators’ temperature, pinch point temperature difference in the evaporators and degree of superheat at the ORC turbines inlet on the exergy efficiency, rate of produced hydrogen and sustainability index of the integrated system are investigated. Using direct search method by the Engineering Equation Solver (EES) software, the combined system is optimized to achieve the maximum exergy efficiency. Results show that the exergy efficiency difference between the combined system and GTMHR cycle increases with an increase in pressure ratio. Also, it is observed that the rate of produced hydrogen increases with increasing turbine inlet temperature and takes the maximum value with change in evaporators’ temperature. Under the optimized condition, exergy efficiency, rate of the produced hydrogen and sustainability index of the proposed combined system are calculated to be 49.21%, 56.2 kg/h and 1.972, respectively.

  16. QTL mapping for combining ability in different population-based ...

    Indian Academy of Sciences (India)

    2013-12-13

    Dec 13, 2013 ... Abstract. The NCII design (North Carolina mating design II) has been widely applied in studies of combining ability and heterosis. The objective of our research was to estimate how different base populations, sample sizes, testcross numbers and heritability influence QTL analyses of combining ability and ...

  17. QTL mapping for combining ability in different population-based ...

    Indian Academy of Sciences (India)

    The NCII design (North Carolina mating design II) has been widely applied in studies of combining ability and heterosis. The objective of our research was to estimate how different base populations, sample sizes, testcross numbers and heritability influence QTL analyses of combining ability and heterosis. A series of Monte ...

  18. Application of optimal design methodologies in retrofitting natural gas combined cycle power plants with CO2 capture

    International Nuclear Information System (INIS)

    Pan, Ming; Aziz, Farah; Li, Baohong; Perry, Simon; Zhang, Nan; Bulatov, Igor; Smith, Robin

    2016-01-01

    Highlights: • A new approach is proposed for retrofitting NGCC power plants with CO2 capture. • HTI techniques are developed for improving heat recovery in NGCC power plants. • EGR techniques are developed to increase the process overall energy efficiency. • The proposed methods are efficient for practical application. - Abstract: Around 21% of the world’s power production is based on natural gas. Energy production is considered to be the significant sources of carbon dioxide (CO 2 ) emissions. This has a significant effect on the global warming. Improving power plant efficiency and adding a CO 2 capture unit into power plants, have been suggested to be a promising countermeasure against global warming. This paper presents a new insight to the application of energy efficient technologies in retrofitting natural gas combined cycle (NGCC) power plants with CO 2 capture. High fidelity models of a 420 MW NGCC power plant and a CO 2 capture plant with CO 2 compression train have been built and integrated for 90% capture level. These models have been then validated by comparisons with practical operating data and literature results. The novelty of the paper is to propose optimal retrofitting strategies to minimize the efficiency penalty caused by integrating carbon capture units into the power plant, including (1) implementing heat transfer intensification techniques to increase energy saving in the heat recovery steam generator (HRSG) of the power plant; (2) extracting suitable steam from the HRSG to supply the heat required by the capture process, thus on external heat is purchased; (3) employing exhaust gas recirculation (EGR) to increase the overall energy efficiency of the integrated process, which can benefit both power plant (e.g. increasing power plant efficiency) and capture process (e.g. reducing heat demands). Compared with the base case without using any integrating and retrofitting strategies, the optimal solution based on the proposed approaches

  19. Oral Presence of Carbohydrate and Caffeine in Chewing Gum: Independent and Combined Effects on Endurance Cycling Performance.

    Science.gov (United States)

    Oberlin-Brown, Katherine T; Siegel, Rodney; Kilding, Andrew E; Laursen, Paul B

    2016-03-01

    The oral presence of carbohydrate (CHO) and caffeine (CAF) may independently enhance exercise performance, but their influence on performance during prolonged exercise is less known. To determine the independent and combined effects of CHO and CAF administered in chewing gum during a cycling time trial (TT) after prolonged exercise. Eleven male cyclists (32.2 ± 7.5 y, 74.3 ± 6.8 kg, 60.2 ± 4.0 mL · kg-1 · min-1 VO2peak) performed 4 experimental trials consisting of 90-min constant-load cycling at 80% of their second ventilatory threshold (207 ± 30 W), followed immediately by a 20-km TT. Under double-blinded conditions, cyclists received placebo (PLA), CHO, CAF, or a combined CHO+CAF chewing gum at 0-, 5-, 10-, and 15-km points of the TT. Overall TT performance was similar across experimental and PLA trials (%mean difference ± 90%CL 0.2% ± 2.0%, 0.4% ± 2.2%, 0.1% ± 1.8% for CHO, CAF, and CHO+CAF). Compared with PLA, mean power output tended to be higher in the first 2 quarters of the TT with CHO (1.6% ± 3.1% and 0.8% ± 2.0%) and was substantially improved in the last 2 quarters during CAF and CHO+CAF trials (4.2% ± 3.0% and 2.0% ± 1.8%). There were no differences in average heart rate (ES performance. Blood lactate was substantially higher post-TT for CAF and CHO+CAF (ES >0.6). After prolonged constant-load cycling, the oral presence of CHO and CAF in chewing gum, independently or in combination, did not improve overall performance but did influence pacing.

  20. Cycle-Based Budgeting and Continuous Improvement at Jefferson County Public Schools: Year 1 Report

    Science.gov (United States)

    Yan, Bo

    2016-01-01

    This report documents the first-year of implementing Cycle-based Budgeting at Jefferson County Public Schools (Louisville, KY). To address the limitations of incremental budgeting and zero-based budgeting, a Cycle-based Budgeting model was developed and implemented in JCPS. Specifically, each new program needs to submit an on-line budget request…

  1. Cryogenic hydrogen-induced air-liquefaction technologies for combined-cycle propulsion applications

    Science.gov (United States)

    Escher, William J. D.

    1992-01-01

    Given here is a technical assessment of the realization of cryogenic hydrogen induced air liquefaction technologies in a prospective onboard aerospace vehicle process setting. The technical findings related to the status of air liquefaction technologies are reviewed. Compact lightweight cryogenic heat exchangers, heat exchanger atmospheric constituent fouling alleviation measures, para/ortho-hydrogen shift-conversion catalysts, cryogenic air compressors and liquid air pumps, hydrogen recycling using slush hydrogen as a heat sink, liquid hydrogen/liquid air rocket-type combustion devices, and technically related engine concepts are discussed. Much of the LACE work is related to aerospaceplane propulsion concepts that were developed in the 1960's. Emphasis is placed on the Liquid Air Cycle Engine (LACE).

  2. Novel Chromosome Organization Pattern in Actinomycetales—Overlapping Replication Cycles Combined with Diploidy

    Science.gov (United States)

    Böhm, Kati; Meyer, Fabian; Rhomberg, Agata; Kalinowski, Jörn; Donovan, Catriona

    2017-01-01

    ABSTRACT Bacteria regulate chromosome replication and segregation tightly with cell division to ensure faithful segregation of DNA to daughter generations. The underlying mechanisms have been addressed in several model species. It became apparent that bacteria have evolved quite different strategies to regulate DNA segregation and chromosomal organization. We have investigated here how the actinobacterium Corynebacterium glutamicum organizes chromosome segregation and DNA replication. Unexpectedly, we found that C. glutamicum cells are at least diploid under all of the conditions tested and that these organisms have overlapping C periods during replication, with both origins initiating replication simultaneously. On the basis of experimental data, we propose growth rate-dependent cell cycle models for C. glutamicum. PMID:28588128

  3. Novel Chromosome Organization Pattern in Actinomycetales—Overlapping Replication Cycles Combined with Diploidy

    Directory of Open Access Journals (Sweden)

    Kati Bohm

    2017-06-01

    Full Text Available Bacteria regulate chromosome replication and segregation tightly with cell division to ensure faithful segregation of DNA to daughter generations. The underlying mechanisms have been addressed in several model species. It became apparent that bacteria have evolved quite different strategies to regulate DNA segregation and chromosomal organization. We have investigated here how the actinobacterium Corynebacterium glutamicum organizes chromosome segregation and DNA replication. Unexpectedly, we found that C. glutamicum cells are at least diploid under all of the conditions tested and that these organisms have overlapping C periods during replication, with both origins initiating replication simultaneously. On the basis of experimental data, we propose growth rate-dependent cell cycle models for C. glutamicum.

  4. Combined use of semantics and metadata to manage Research Data Life Cycle in Environmental Sciences

    Science.gov (United States)

    Aguilar Gómez, Fernando; de Lucas, Jesús Marco; Pertinez, Esther; Palacio, Aida

    2017-04-01

    The use of metadata to contextualize datasets is quite extended in Earth System Sciences. There are some initiatives and available tools to help data managers to choose the best metadata standard that fit their use cases, like the DCC Metadata Directory (http://www.dcc.ac.uk/resources/metadata-standards). In our use case, we have been gathering physical, chemical and biological data from a water reservoir since 2010. A well metadata definition is crucial not only to contextualize our own data but also to integrate datasets from other sources like satellites or meteorological agencies. That is why we have chosen EML (Ecological Metadata Language), which integrates many different elements to define a dataset, including the project context, instrumentation and parameters definition, and the software used to process, provide quality controls and include the publication details. Those metadata elements can contribute to help both human and machines to understand and process the dataset. However, the use of metadata is not enough to fully support the data life cycle, from the Data Management Plan definition to the Publication and Re-use. To do so, we need to define not only metadata and attributes but also the relationships between them, so semantics are needed. Ontologies, being a knowledge representation, can contribute to define the elements of a research data life cycle, including DMP, datasets, software, etc. They also can define how the different elements are related between them and how they interact. The first advantage of developing an ontology of a knowledge domain is that they provide a common vocabulary hierarchy (i.e. a conceptual schema) that can be used and standardized by all the agents interested in the domain (either humans or machines). This way of using ontologies is one of the basis of the Semantic Web, where ontologies are set to play a key role in establishing a common terminology between agents. To develop an ontology we are using a graphical tool

  5. Combined-cycle steam section parametric analysis by thermo-economic simulation

    International Nuclear Information System (INIS)

    Macor, A.; Reini, M.

    1991-01-01

    In the case of industrial cogeneration plants, thermal power production is, in general, strictly dependent on the technological requirements of the production cycle, whereas, the electrical power which is produced can be auto- consumed or ceded to the utility grid. In both cases, an economic worth is given to this energy which influences the overall economic feasibility of the plant. The purpose of this paper is to examine parametric inter-relationships between economic and thermodynamic performance optimization techniques. Comparisons are then made of the results obtained with the use of the thermo- economic analysis technique suggested in this paper with those obtained with the use of indicators in other exergo-economic analysis techniques

  6. Environmental control implications of generating electric power from coal. Appendix C. Gasification/combined-cycle power generation: comparison of alternative systems. 1977 technology status report. [246 references w. abstracts

    Energy Technology Data Exchange (ETDEWEB)

    None

    1977-12-01

    The technical, economic, and environmental aspects of low-Btu gasification/combined-cycle power-generation (LBG/CCPG) plants are assessed, using available published data. Six base-case plants, based on three different gasifiers and two different coals, are investigated. A representative combined power cycle is selected for analysis, and material and energy balances for the six systems are developed. Emissions of various air pollutants, including sulfur dioxide and nitrogen oxides, and discharge rates of aqueous effluents are also calculated. The costs of electricity produced are derived for the six systems, using estimated plant-investment and operating costs. These costs and the emissions of various pollutants are compared with those for a conventional 500-MWe coal-based power plant using flue-gas cleaning and in compliance with the federal New Source Performance Standards. Finally, the commercialization potential of coal-based combined-cycle plants, based on the technical feasibility of building a first plant in the 1985 period and on economic viability, is evaluated. This evaluation is based on the current status of research and development programs for various components of the combined-cycle plant, such as gas turbines and fuel-gas-cleaning systems, and on the status of the demonstration plant.

  7. Environmental impacts of combining pig slurry acidification and separation under different regulatory regimes - a life cycle assessment

    DEFF Research Database (Denmark)

    ten Hoeve, Marieke; Gomez Muñoz, Beatriz; Jensen, Lars Stoumann

    2016-01-01

    Global livestock production is increasing rapidly, leading to larger amounts of manure and environmental impacts. Technologies that can be applied to treat manure in order to decrease certain environmental impacts include separation and acidification. In this study, a life cycle assessment was used...... separation led to a lower freshwater eutrophication potential than the other scenarios in which N regulations alone were in force, while these environmental benefits disappeared after implementation of stricter P regulations. With N regulations alone, there was a synergetic positive effect of combining in...

  8. Dynamic performance of a combined gas turbine and air bottoming cycle plant for off-shore applications

    DEFF Research Database (Denmark)

    Benato, Alberto; Pierobon, Leonardo; Haglind, Fredrik

    2014-01-01

    and a combined gas turbine coupled with an air bottoming cycle plant. The case study is the Draugen off-shore oil and gas platform, located in the North Sea, Norway. The normal electricity demand is 19 MW, currently covered by two gas turbines generating each 50% of the power demand, while the third turbine...... is on stand-by. During oil export operations the power demand increases up to 25 MW. The model of the new power plant proposed in this work is developed in the Modelica language using basic components acquired from ThermoPower, a library for power plant modelling. The dynamic model of the gas turbine...

  9. Importance of cell cycle perturbations on the effectiveness of N-methylformamide and anti-neoplastic drugs in combination.

    Science.gov (United States)

    Cucco, C; D'Agnano, I; Marangolo, M; Candiloro, A; Zupi, G

    1991-05-01

    The effect of N-methylformamide (NMF) in combination with Adriamycin (ADM) and cis-diamminedichloroplatinum (DDP) on the cell survival and cell cycle kinetics of two human tumour lines was assessed: HT29 colon carcinoma and M14 melanoma cells were exposed to ADM and DDP alone or in combination with a non-cytotoxic dose of NMF, according to different schedules. The results demonstrate that NMF exposure sensitized both tumour cell lines to the lethal activity of ADM and DDP; however, reverse sequences had to be applied to reach an increase in the lethal activity of the two different drugs. The ADM-NMF combination determined a powerful decrease in the surviving fraction of the two cell lines when ADM was given as the first agent (ADM----NMF), while the reverse sequence did not increase the ADM cytotoxic effect. With respect to the DDP-NMF association, the sequence which accounted for a greater sensitizing effect was NMF administration followed by DDP treatment (NMF----DDP). This work demonstrates the importance of timing in combined treatments which involve NMF. A delay in cell proliferation elicited by NMF exposure could be responsible for the effectiveness of the combined treatment.

  10. Parametric Optimization of Regenerative Organic Rankine Cycle System for Diesel Engine Based on Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Hongjin Wang

    2015-09-01

    Full Text Available To efficiently recover the waste heat from a diesel engine exhaust, a regenerative organic Rankine cycle (RORC system was employed, and butane, R124, R416A, and R134a were used as the working fluids. The resulting diesel engine-RORC combined system was defined and the relevant evaluation indexes were proposed. First, the variation tendency of the exhaust energy rate under various diesel engine operating conditions was analyzed using experimental data. The thermodynamic model of the RORC system was established based on the first and second laws of thermodynamics, and the net power output and exergy destruction rate of the RORC system were selected as the objective functions. A particle swarm optimization (PSO algorithm was used to optimize the operating parameters of the RORC system, including evaporating pressure, intermediate pressure, and degree of superheat. The operating performances of the RORC system and diesel engine-RORC combined system were studied for the four selected working fluids under various operating conditions of the diesel engine. The results show that the operating performances of the RORC system and the combined system using butane are optimal on the basis of optimizing the operating parameters; when the engine speed is 2200 r/min and engine torque is 1215 N·m, the net power output of the RORC system using butane is 36.57 kW, and the power output increasing ratio (POIR of the combined system using butane is 11.56%.

  11. Biomolecular Network-Based Synergistic Drug Combination Discovery

    Directory of Open Access Journals (Sweden)

    Xiangyi Li

    2016-01-01

    Full Text Available Drug combination is a powerful and promising approach for complex disease therapy such as cancer and cardiovascular disease. However, the number of synergistic drug combinations approved by the Food and Drug Administration is very small. To bridge the gap between urgent need and low yield, researchers have constructed various models to identify synergistic drug combinations. Among these models, biomolecular network-based model is outstanding because of its ability to reflect and illustrate the relationships among drugs, disease-related genes, therapeutic targets, and disease-specific signaling pathways as a system. In this review, we analyzed and classified models for synergistic drug combination prediction in recent decade according to their respective algorithms. Besides, we collected useful resources including databases and analysis tools for synergistic drug combination prediction. It should provide a quick resource for computational biologists who work with network medicine or synergistic drug combination designing.

  12. Memory-based detection of rare sound feature combinations in anesthetized rats.

    Science.gov (United States)

    Astikainen, Piia; Ruusuvirta, Timo; Wikgren, Jan; Penttonen, Markku

    2006-10-02

    It is unclear whether the ability of the brain to discriminate rare from frequently repeated combinations of sound features is limited to the normal sleep/wake cycle. We recorded epidural auditory event-related potentials in urethane-anesthetized rats presented with rare tones ('deviants') interspersed with frequently repeated ones ('standards'). Deviants differed from standards either in frequency alone or in frequency combined with intensity. In both cases, deviants elicited event-related potentials exceeding in amplitude event-related potentials to standards between 76 and 108 ms from the stimulus onset, suggesting the independence of the underlying integrative and memory-based change detection mechanisms of the brain from the normal sleep/wake cycle. The relations of these event-related potentials to mismatch negativity and N1 in humans are addressed.

  13. Thermodynamic optimization of the operating parameters for a combined power cycle utilizing low-temperature waste heat and LNG cold energy

    International Nuclear Information System (INIS)

    Wang, Huan; Shi, Xiaojun; Che, Defu

    2013-01-01

    This paper deals with the optimization of a novel combined power system, which can effectively recover low-temperature waste heat and fully utilize the cold energy of LNG as well, based on the first thermodynamic law and the second thermodynamic law respectively. Parametric analysis has been performed to study the effects of heat source temperature, ammonia turbine inlet pressure, LNG turbine inlet and outlet pressures, as well as ammonia mass fraction of basic solution. The simulation results show that the system performance can be improved by applying optimization techniques. The optimization is conducted under a certain set of constraints by using the differential evolution (DE) algorithm to maximize the first and the second law efficiency respectively. Through parallel direct search over the whole feasible region, it is found that a maximum first law efficiency of 39.33% can be obtained when variable vector V 1 = [423.70 K, 1.8 MPa, 3.904 MPa, 0.3 MPa, 0.52]; while a maximum second law efficiency of 55.62% can be obtained when variable vector V 2 = [423.93 K, 1.874 MPa, 3.493 MPa, 0.8 MPa, 0.48]. In addition, the irreversibilities in various components of the cycle under typical operating conditions and exergy efficiency optimum condition have been compared through detailed exergy analysis. -- Highlights: • The combined power cycle utilizes low-temperature waste heat and LNG cold energy. • Parametric analysis results recommended that the cycle may be optimized. • Thermal and exergy efficiency were selected as objective functions separately. • Differential evolution algorithm was applied to reach the maximum efficiency. • Optimization of operating parameters improved the cycle performance significantly

  14. Life cycle analysis of distributed concentrating solar combined heat and power: economics, global warming potential and water

    Science.gov (United States)

    Norwood, Zack; Kammen, Daniel

    2012-12-01

    We report on life cycle assessment (LCA) of the economics, global warming potential and water (both for desalination and water use in operation) for a distributed concentrating solar combined heat and power (DCS-CHP) system. Detailed simulation of system performance across 1020 sites in the US combined with a sensible cost allocation scheme informs this LCA. We forecast a levelized cost of 0.25 kWh-1 electricity and 0.03 kWh-1 thermal, for a system with a life cycle global warming potential of ˜80 gCO2eq kWh-1 of electricity and ˜10 gCO2eq kWh-1 thermal, sited in Oakland, California. On the basis of the economics shown for air cooling, and the fact that any combined heat and power system reduces the need for cooling while at the same time boosting the overall solar efficiency of the system, DCS-CHP compares favorably to other electric power generation systems in terms of minimization of water use in the maintenance and operation of the plant. The outlook for water desalination coupled with distributed concentrating solar combined heat and power is less favorable. At a projected cost of 1.40 m-3, water desalination with DCS-CHP would be economical and practical only in areas where water is very scarce or moderately expensive, primarily available through the informal sector, and where contaminated or salt water is easily available as feed-water. It is also interesting to note that 0.40-1.90 m-3 is the range of water prices in the developed world, so DCS-CHP desalination systems could also be an economical solution there under some conditions.

  15. Height estimations based on eye measurements throughout a gait cycle

    DEFF Research Database (Denmark)

    Yang, Sylvia X M; Larsen, Peter K; Alkjær, Tine

    2014-01-01

    (EH) measurement, on the other hand, is less prone to concealment. The purpose of the present study was to investigate: (1) how the eye height varies during the gait cycle, and (2) how the eye height changes with head position. The eyes were plotted manually in APAS for 16 test subjects during...

  16. Formal TCA cycle description based on elementary actions

    Indian Academy of Sciences (India)

    Prakash

    2006-12-20

    Dec 20, 2006 ... BioΨ allows the formal integration of functional information existing in current databases and make them available for further automated analysis. In addition such a formal TCA cycle process description leads to a more accurate biological process annotation which takes in account the biological context.

  17. Environmental correlates of cycling: Evaluating urban form and location effects based on Danish micro-data

    DEFF Research Database (Denmark)

    Nielsen, Thomas Alexander Sick; Olafsson, Anton Stahl; Carstensen, Trine Agervig

    2013-01-01

    transportation level-of-service, as well as competition between walking and cycling depending on environmental features can be added. Attractive conditions for using public transportation or walking are related to less cycling. The findings quantify the effects of urban form on the probability of cycling......The paper analyses the environmental correlates of cycling based on Danish transportation and urban form micro-data. The results show that established walkability factors such as density, connectivity and diversity are related to cycling, but access to retail concentrations/centres, public...

  18. TRI HITA KARANA AND HYDROLIC CYCLE BASED ON VEDA

    Directory of Open Access Journals (Sweden)

    A.A. Kade Sri Yudari

    2015-10-01

    Full Text Available Hydrologic cycle refers to the route of water cycle or the journey made by water on the earth’s surface. Water can change in form, and flows in various places before finally it gets back to the biggest source, that is, the ocean. Approximately 71% of the earth is covered with the ocean. Talking about the hydrologic cycle cannot be separated from talking about the sun and the ocean, that is, the impact of the rise and fall of the tides. In Veda, the traditional geography, in general, and in Tatwa and Purana, in particular, it is stated that the earth is divided into two parts; they are the main land and the ocean. The question is how deep the Hindu theology and philosophy about the hydrologic cycle is. The water on the earth’s surface evaporates, resulting from the hot ray radiated by the sun. In Reg. Veda Samhita.I.164.51, it is strongly stated that “the water on the earth’s surface rises due to evaporation”. After evaporation, water changes into water drops or fine dews referred to as clouds. There are many types and forms of clouds which may lead to storms; however, some have no impact. When such clouds are already formed, they are brought to every area of the earth’s surface. When they reach the saturation point, a natural phenomenon appears which is referred to as rain. The falling water makes the earth wet, fills up dams, flows along rivers, and fertilize every type of life on earth. Rain measures how the hydrologic cycle takes place. Therefore, it should be recognized that it is important to maintain the hydrologic cycle, which determines that the earth’s fertility and prosperity will not be disturbed. The Hindu teaching is rich in such a philosophy referred to as Tri Hita Karana. Even in very religious ritual water is always mainly used for purification. The sources of water such as wells, rivers, lakes, showers, and oceans are made to be physically and spiritually sacred. The concepts of balance and harmony are easily found

  19. Development of FBR cycle data base system (II)

    International Nuclear Information System (INIS)

    Kubota, Sadae; Ohtaki, Akira; Hirao, Kazuhiro

    2003-05-01

    In the 'Feasibility Study on Commercialized FBR Cycle Systems (F/S)', scenario evaluations, cost-benefit evaluations and system characteristic evaluations to show the significance of the FBR cycle system introduction concretely are performed while design studies for FBR plants, reprocessing systems and fabrication systems are conducted. In these evaluations, future society of various conditions and situation is assumed, and investigation and analysis about needs and social effects of FBR cycle are carried out. In this study, promising FBR cycle concepts are suggested by taking information such as domestic and foreign policies and bills, an economic prediction, a supply and demand prediction of resources, a project of technology development into consideration in addition to system design information. The development of the FBR Cycle Database which this report introduced started in 1999 fiscal year to enable managed unitarity and searched reference information to use for the above scenario evaluations, cost-benefit evaluations and system characteristic evaluations. In 2000 fiscal year, its prototype was made and used tentatively, and we extracted the problems in operation and functions from that, and, in 2001 fiscal year, the entry system and the search system using the Web page were made in order to solve problems of the prototype, and started use in our group. Moreover, in 2002 fiscal year, we expanded and improved the search system and promoted the efficiency of management work, and use in JNC through intranet of the database was started. In addition, as a result of having made the entry of about 350 data in 2002 fiscal year, the collected number of the database reaches about 7,250 by the end of March, 2003. We are to continue the entry of related information of various evaluations in F/S phase 2 from now on. In addition, we are to examine improvement of convenience of the search system and cooperation with the economy database. (author)

  20. Optimization and the effect of steam turbine outlet quality on the output power of a combined cycle power plant

    International Nuclear Information System (INIS)

    Ganjehkaviri, A.; Mohd Jaafar, M.N.; Hosseini, S.E.

    2015-01-01

    Highlights: • Comprehensive thermodynamic modeling of combined cycle power plant. • Multi-objective optimization of a CCPP with genetic algorithm. • To improve the system performance by using an optimization approach. • To compare the performance of three different systems with different quality. - Abstract: A narrow path exists to a sustainable solution which passes through careful steps of efficiency improvement (resource management) and provides environmental friendly energies. Thermal power plants are more common in many power production sites around the world. Therefore, in this current research study a comprehensive thermodynamic modeling of a combined cycle power plant with dual pressure heat recovery steam generator is presented. Since the steam turbine outlet quality is a restrictive parameter, optimization of three cases with different steam quality are conducted and discussed. In other hand, energy and exergy analysis of each components for these three different cases estimated and compared. Obtained results show that it is really important to keep the quality of the vapor at turbine outlet constant in 88% for the results to be more realistic and also optimization and data are more technically feasible and applicable

  1. Improving the exergy efficiency of a cryogenic air separation unit as part of an integrated gasification combined cycle

    International Nuclear Information System (INIS)

    Ham, L.V. van der

    2012-01-01

    Graphical abstract: Display Omitted Highlights: ► Cryogenic air separation as part of an integrated gasification combined cycle. ► Considerable improvements in the exergy efficiency of a two-column design. ► Heating the separation products using heat of compression. ► Improving heat integration of the columns using heat-integrated distillation stages. - Abstract: The efficiency of a two-column cryogenic ASU (air separation unit) that is part of an IGCC (integrated gasification combined cycle) can be increased significantly by making better use of the heat of compression and by improving the heat integration of the distillation columns. The rational exergy efficiency of the ASU, which is defined as the desired increase in exergy content of the products divided by the amount of work that is added to the process, can be increased from 35% to over 70%. The exergy destruction per amount of feed is reduced with 1.6 kJ/mol air, corresponding to a 0.74% increase in the net electric efficiency of the IGCC. The efficiencies are expected to increase even further because the full potential of using heat-integrated distillation columns is not yet achieved.

  2. The impact of using the combined oral contraceptive pill for cycle scheduling on gene expression related to endometrial receptivity.

    Science.gov (United States)

    Bermejo, Alfonso; Iglesias, Carlos; Ruiz-Alonso, María; Blesa, David; Simón, Carlos; Pellicer, Antonio; García-Velasco, Juan

    2014-06-01

    Does the combined oral contraceptive pill (COCP) change endometrial gene expression when used for cycle programming? COCP used for scheduling purposes does not have a significant impact on endometrial gene expression related to endometrial receptivity. Controversy exists around COCP pretreatment for IVF cycle programming, as some authors claim that it might be detrimental to the live birth rate. Microarray technology applied to the study of tissue gene expression has previously revealed the behavior of genes related to endometrial receptivity under different conditions. Proof-of-concept study of 10 young healthy oocyte donors undergoing controlled ovarian stimulation (COS) recruited between June 2012 and February 2013. Microarray data were obtained from endometrial biopsies from 10 young healthy oocyte donors undergoing COS with GnRH antagonists and recombinant FSH. In group A (n = 5), COCP pretreatment was used for 12-16 days, and stimulation began after a 5-day pill-free interval. Stimulation in group B (n = 5) was initiated on cycle day 3 after a spontaneous menses. Endometrial biopsies were collected 7 days after triggering with hCG. No individual genes exhibited increased or decreased expression (fold change (FC) >2) in patients with prior COCP treatment (group A) compared with controls (group B). However, the results of the functional analysis showed a total of 11 biological processes that were significantly enriched in group A compared with group B (non-COCP). The Endometrial Receptivity Array (ERA) has only been validated on endometrial samples obtained in natural cycles and after hormonal replacement treatment (HRT). Therefore, it was not possible in this study to classify the endometrial samples as receptive or non-receptive. We used the ERA to focus on 238 genes that are intimately related to endometrial receptivity, thus simplifying the analysis and understanding of the data. Cycle scheduling is common in IVF units and is used to avoid weekend

  3. Functioning of nitric oxide cycle in gastric mucosa of rats under excessive combined intake of sodium nitrate and fluoride.

    Science.gov (United States)

    Akimov, O Ye; Kostenko, V O

    2016-01-01

    In the article the function of nitric oxide (·NO) cycle in rat’s gastric mucosa was assessed under excessive combined chronic fluoride and nitrate intake during 30 days. It was estimated that general nitric oxide synthase activity (NOS) was increased during excessive sodium fluoride intake meanwhile influence on gene­ral nitrate reduction was not statistically significant, but general nitrite reduction was increased. General arginase activity decreased. Excessive sodium nitrate intake decreased NOS activity, but increased nitrate, nitrite reduction and general arginase activity. Combined sodium nitrate and fluoride intake increased NOS by 18.9%, nitrate reduction by 71.7%, nitrite by 161.5%, arginase activity increase by 61.4%. The highest amounts of peroxynitrite were obtained from excessive sodium fluoride intake group, excessive sodium nitrate intake showed the lowest levels and combined excessive sodium nitrate and fluoride intake levels had intermediate results. Summarizing the data obtained, the authors have made a conclusion that combined excessive sodium nitrate and fluoride intake creates optimal conditions for functioning of nitrate-nitrite reductases.

  4. Alternative analysis to increase the power in combined-cycle power plants; Analisis de alternativas para el incremento de potencia en plantas termoelectricas de Ciclo Combinado

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco Cruz, Hector; Arriola Medellin, Alejandro M. [Gerencia de Procesos Termicos, Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: hpacheco@iie.org.mx; aarriola@iie.org.mx

    2010-11-15

    The electricity industry traditionally had two thermodynamic cycles for power generation: conventional steam turbine (Rankine cycle) used to supply a base load during the day, and gas turbines (Brayton cycle), for its speed response, normally used to cover peak loads. However, to provide variable peak loads, the gas turbine, as a volumetric machine is affected by the change in air density by changing the combustion temperature. This paper shows the scheme of integration of both systems, that it's known as combined cycle and the different options that would have these power plants, to maintain or increase their power in variable ambient conditions. It analyzes different options, such as: 1. Supplementary fire in the stove. 2. Air cooling intake in the gas turbine (evaporation system or mechanical system). 3. Steam injection in the combustion chamber. [Spanish] La industria electrica tradicionalmente a contado con dos ciclos termodinamicos para generacion electrica: las turbinas convencionales de vapor (ciclo de Rankine) se utilizan para suministrar una carga base durante el dia, y las turbinas de gas (ciclo de Brayton), por su rapidez de respuesta, se utilizan normalmente para cubrir las cargas pico. Sin embargo, para suministrar las cargas variables pico, la turbina a gas, por ser una maquina volumetrica, se ve afectada por el cambio de la densidad del aire de combustion al cambiar la temperatura ambiente. En este trabajo se muestra el esquema de integracion de ambos sistemas, en lo que se conoce como ciclo combinado y las diferentes opciones que tendrian estas plantas de generacion electrica para mantener o incrementar su potencia en condiciones ambiente variable. Para ello se analizan diferentes opciones, tales como: 1.- Combustion suplementaria en el recuperador de calor. 2.- Enfriamiento del aire de admision a la turbina de gas (mediante un sistema de evaporacion o mediante un sistema mecanico). 3.- Inyeccion de vapor a la camara de combustion. Palabras

  5. Life-cycle cost assessment of seismically base-isolated structures in nuclear power plants

    International Nuclear Information System (INIS)

    Wang, Hao; Weng, Dagen; Lu, Xilin; Lu, Liang

    2013-01-01

    Highlights: • The life-cycle cost of seismic base-isolated nuclear power plants is modeled. • The change law of life-cycle cost with seismic fortification intensity is studied. • The initial cost of laminated lead rubber bearings can be expressed as the function of volume. • The initial cost of a damper can be expressed as the function of its maximum displacement and tonnage. • The use of base-isolation can greatly reduce the expected damage cost, which leads to the reduction of the life-cycle cost. -- Abstract: Evaluation of seismically base-isolated structural life-cycle cost is the key problem in performance based seismic design. A method is being introduced to address the life-cycle cost of base-isolated reinforced concrete structures in nuclear power plants. Each composition of life-cycle cost is analyzed including the initial construction cost, the isolators cost and the excepted damage cost over life-cycle of the structure. The concept of seismic intensity is being used to estimate the expected damage cost, greatly simplifying the calculation. Moreover, French Cruas nuclear power plant is employed as an example to assess its life-cycle cost, compared to the cost of non-isolated plant at the same time. The results show that the proposed method is efficient and the expected damage cost is enormously reduced because of the application of isolators, which leads to the reduction of the life-cycle cost of nuclear power plants

  6. A strategy for selective detection based on interferent depleting and redox cycling using the plane-recessed microdisk array electrodes

    International Nuclear Information System (INIS)

    Zhu Feng; Yan Jiawei; Lu Miao; Zhou Yongliang; Yang Yang; Mao Bingwei

    2011-01-01

    Highlights: → A novel strategy based on a combination of interferent depleting and redox cycling is proposed for the plane-recessed microdisk array electrodes. → The strategy break up the restriction of selectively detecting a species that exhibits reversible reaction in a mixture with one that exhibits an irreversible reaction. → The electrodes enhance the current signal by redox cycling. → The electrodes can work regardless of the reversibility of interfering species. - Abstract: The fabrication, characterization and application of the plane-recessed microdisk array electrodes for selective detection are demonstrated. The electrodes, fabricated by lithographic microfabrication technology, are composed of a planar film electrode and a 32 x 32 recessed microdisk array electrode. Different from commonly used redox cycling operating mode for array configurations such as interdigitated array electrodes, a novel strategy based on a combination of interferent depleting and redox cycling is proposed for the electrodes with an appropriate configuration. The planar film electrode (the plane electrode) is used to deplete the interferent in the diffusion layer. The recessed microdisk array electrode (the microdisk array), locating within the diffusion layer of the plane electrode, works for detecting the target analyte in the interferent-depleted diffusion layer. In addition, the microdisk array overcomes the disadvantage of low current signal for a single microelectrode. Moreover, the current signal of the target analyte that undergoes reversible electron transfer can be enhanced due to the redox cycling between the plane electrode and the microdisk array. Based on the above working principle, the plane-recessed microdisk array electrodes break up the restriction of selectively detecting a species that exhibits reversible reaction in a mixture with one that exhibits an irreversible reaction, which is a limitation of single redox cycling operating mode. The

  7. Consequential environmental and economic life cycle assessment of green and gray stormwater infrastructures for combined sewer systems.

    Science.gov (United States)

    Wang, Ranran; Eckelman, Matthew J; Zimmerman, Julie B

    2013-10-01

    A consequential life cycle assessment (LCA) is conducted to evaluate the trade-offs between water quality improvements and the incremental climate, resource, and economic costs of implementing green (bioretention basin, green roof, and permeable pavement) versus gray (municipal separate stormwater sewer systems, MS4) alternatives of stormwater infrastructure expansions against a baseline combined sewer system with combined sewer overflows in a typical Northeast US watershed for typical, dry, and wet years. Results show that bioretention basins can achieve water quality improvement goals (e.g., mitigating freshwater eutrophication) for the least climate and economic costs of 61 kg CO2 eq. and $98 per kg P eq. reduction, respectively. MS4 demonstrates the minimum life cycle fossil energy use of 42 kg oil eq. per kg P eq. reduction. When integrated with the expansion in stormwater infrastructure, implementation of advanced wastewater treatment processes can further reduce the impact of stormwater runoff on aquatic environment at a minimal environmental cost (77 kg CO2 eq. per kg P eq. reduction), which provides support and valuable insights for the further development of integrated management of stormwater and wastewater. The consideration of critical model parameters (i.e., precipitation intensity, land imperviousness, and infrastructure life expectancy) highlighted the importance and implications of varying local conditions and infrastructure characteristics on the costs and benefits of stormwater management. Of particular note is that the impact of MS4 on the local aquatic environment is highly dependent on local runoff quality indicating that a combined system of green infrastructure prior to MS4 potentially provides a more cost-effective improvement to local water quality.

  8. Power and Efficiency Analysis of a Solar Central Receiver Combined Cycle Plant with a Small Particle Heat Exchanger Receiver

    Science.gov (United States)

    Virgen, Matthew Miguel

    Two significant goals in solar plant operation are lower cost and higher efficiencies. To achieve those goals, a combined cycle gas turbine (CCGT) system, which uses the hot gas turbine exhaust to produce superheated steam for a bottoming Rankine cycle by way of a heat recovery steam generator (HRSG), is investigated in this work. Building off of a previous gas turbine model created at the Combustion and Solar Energy Laboratory at SDSU, here are added the HRSG and steam turbine model, which had to handle significant change in the mass flow and temperature of air exiting the gas turbine due to varying solar input. A wide range of cases were run to explore options for maximizing both power and efficiency from the proposed CSP CCGT plant. Variable guide vanes (VGVs) were found in the earlier model to be an effective tool in providing operational flexibility to address the variable nature of solar input. Combined cycle efficiencies in the range of 50% were found to result from this plant configuration. However, a combustor inlet temperature (CIT) limit leads to two distinct Modes of operation, with a sharp drop in both plant efficiency and power occurring when the air flow through the receiver exceeded the CIT limit. This drawback can be partially addressed through strategic use of the VGVs. Since system response is fully established for the relevant range of solar input and variable guide vane angles, the System Advisor Model (SAM) from NREL can be used to find what the actual expected solar input would be over the course of the day, and plan accordingly. While the SAM software is not yet equipped to model a Brayton cycle cavity receiver, appropriate approximations were made in order to produce a suitable heliostat field to fit this system. Since the SPHER uses carbon nano-particles as the solar absorbers, questions of particle longevity and how the particles might affect the flame behavior in the combustor were addressed using the chemical kinetics software Chemkin

  9. Cell cycle kinetic analysis of colorectal neoplasms using a new automated immunohistochemistry-based cell cycle detection method.

    Science.gov (United States)

    Tomono, Ayako; Itoh, Tomoo; Yanagita, Emmy; Imagawa, Naoko; Kakeji, Yoshihiro

    2015-01-01

    We have recently developed a new method called the immunohistochemistry-based cell cycle detection (iCCD), which allows the determination of cell cycle phases on a cell-by-cell basis. This automated procedure can be performed on tissue sections and involves triple immunostaining for geminin, cdt1, and γ H2A.X, which are nuclear proteins expressed sequentially, with a few overlaps, during the cell cycle. In the current study, we applied this technique to resected specimens of colorectal neoplasm to determine the usefulness of iCCD for the pathological examination of colorectal cancers. We examined 141 cases of colorectal cancers. Normal mucosa and adenomas were analyzed as controls. In nonneoplastic mucosa, we observed a pattern of distribution of the cells positive for these cell cycle markers. Adenomas showed a slight distortion in this pattern, the geminin-positive cells, indicative of S/G2/M phase, were localized in the upper one-third region of the crypts. In neoplastic mucosa, the marker expression pattern was disorganized. Compared with normal mucosa, colorectal neoplasms showed an increased proportion of geminin-positive cells and decreased percentages of cdt1-positive cells (G1 phase). However, we did not find significant difference in the expression pattern between adenomas and carcinomas. Cellular proportions were correlated with clinicopathological parameters such as microscopic vascular invasion and pT stages. In cases of preoperative adjuvant therapy, the proportion of geminin-positive cells decreased, whereas that of γ H2A.X-positive cells (indicative of apoptosis/degeneration) increased significantly. We believe that this novel method can be applied to clinical samples to evaluate cell cycle kinetics and the effects of preoperative adjuvant therapy in colorectal cancers.

  10. Quasi-static earthquake cycle simulation based on nonlinear viscoelastic finite element analyses

    Science.gov (United States)

    Agata, R.; Ichimura, T.; Hyodo, M.; Barbot, S.; Hori, T.

    2017-12-01

    To explain earthquake generation processes, simulation methods of earthquake cycles have been studied. For such simulations, the combination of the rate- and state-dependent friction law at the fault plane and the boundary integral method based on Green's function in an elastic half space is widely used (e.g. Hori 2009; Barbot et al. 2012). In this approach, stress change around the fault plane due to crustal deformation can be computed analytically, while the effects of complex physics such as mantle rheology and gravity are generally not taken into account. To consider such effects, we seek to develop an earthquake cycle simulation combining crustal deformation computation based on the finite element (FE) method with the rate- and state-dependent friction law. Since the drawback of this approach is the computational cost associated with obtaining numerical solutions, we adopt a recently developed fast and scalable FE solver (Ichimura et al. 2016), which assumes use of supercomputers, to solve the problem in a realistic time. As in the previous approach, we solve the governing equations consisting of the rate- and state-dependent friction law. In solving the equations, we compute stress changes along the fault plane due to crustal deformation using FE simulation, instead of computing them by superimposing slip response function as in the previous approach. In stress change computation, we take into account nonlinear viscoelastic deformation in the asthenosphere. In the presentation, we will show simulation results in a normative three-dimensional problem, where a circular-shaped velocity-weakening area is set in a square-shaped fault plane. The results with and without nonlinear viscosity in the asthenosphere will be compared. We also plan to apply the developed code to simulate the post-earthquake deformation of a megathrust earthquake, such as the 2011 Tohoku earthquake. Acknowledgment: The results were obtained using the K computer at the RIKEN (Proposal number

  11. Assessing sensorimotor excitability after spinal cord injury: a reflex testing method based on cycling with afferent stimulation.

    Science.gov (United States)

    Piazza, Stefano; Torricelli, Diego; Gómez-Soriano, Julio; Serrano-Muñoz, Diego; Ávila-Martín, Gerardo; Galán-Arriero, Iriana; Pons, José Luis; Taylor, Julian

    2018-01-17

    Several studies have examined spinal reflex modulation during leg cycling in healthy and spinal cord injury (SCI) subjects. However, the effect of cutaneous plantar afferent input on spinal excitability during leg cycling after SCI has not been characterised. The aim of the study was to test the feasibility of using controlled leg cycling in combination with plantar cutaneous electrical stimulation (ES) cycling to assess lower limb spinal sensorimotor excitability in subjects with motor complete or incomplete SCI. Spinal sensorimotor excitability was estimated by measuring cutaneomuscular-conditioned soleus H-reflex activity. Reflex excitability was tested before and after a 10-min ES cycling session in 13 non-injured subjects, 6 subjects with motor incomplete SCI (iSCI) who had moderately impaired gait function, 4 subjects with motor iSCI who had severely impaired gait function, and 5 subjects with motor complete SCI (cSCI). No modulation of soleus H-reflex with plantar cutaneous stimuli was observed after either iSCI or cSCI when compared to non-injured subjects. However, after ES cycling, reflex excitability significantly increased in subjects with iSCI and moderately impaired gait function. ES cycling facilitated spinal sensorimotor excitability only in subjects with motor iSCI with residual gait function. Increased spinal excitability induced with a combination of exercise and afferent stimulation could be adopted with diagnostic and prognostic purposes to reveal the activity-based neurorehabilitation profile of individual subjects with motor iSCI. ISRCTN 26172500 ; retrospectively registered on 15 July 2016 Graphical abstract ᅟ.

  12. Solid-Fueled Pressurized Chemical Looping with Flue-Gas Turbine Combined Cycle for Improved Plant Efficiency and CO2 Capture

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kunlei [Univ. of Kentucky, Lexington, KY (United States); Chen, Liangyong [Univ. of Kentucky, Lexington, KY (United States); Zhang, Yi [Univ. of Kentucky, Lexington, KY (United States); Richburg, Lisa [Univ. of Kentucky, Lexington, KY (United States); Simpson, James [WorleyParsons Group Inc., Reading, PA (United States); White, Jay [WorleyParsons Group Inc., Reading, PA (United States); Rossi, Gianalfredo [WorleyParsons Group Inc., Reading, PA (United States)

    2013-12-31

    The purpose of this document is to report the final result of techno-economic analysis for the proposed 550MWe integrated pressurized chemical looping combustion combined cycle process. An Aspen Plus based model is delivered in this report along with the results from three sensitivity scenarios including the operating pressure, excess air ratio and oxygen carrier performance. A process flow diagram and detailed stream table for the base case are also provided with the overall plant energy balance, carbon balance, sulfur balance and water balance. The approach to the process and key component simulation are explained. The economic analysis (OPEX and CAPX) on four study cases via DOE NETL Reference Case 12 are presented and explained.

  13. Model-based efficiency evaluation of combine harvester traction drives

    Directory of Open Access Journals (Sweden)

    Steffen Häberle

    2015-08-01

    Full Text Available As part of the research the drive train of the combine harvesters is investigated in detail. The focus on load and power distribution, energy consumption and usage distribution are explicitly explored on two test machines. Based on the lessons learned during field operations, model-based studies of energy saving potential in the traction train of combine harvesters can now be quantified. Beyond that the virtual machine trial provides an opportunity to compare innovative drivetrain architectures and control solutions under reproducible conditions. As a result, an evaluation method is presented and generically used to draw comparisons under local representative operating conditions.

  14. GPS Cycle Slip Detection Considering Satellite Geometry Based on TDCP/INS Integrated Navigation

    OpenAIRE

    Kim, Younsil; Song, Junesol; Kee, Changdon; Park, Byungwoon

    2015-01-01

    This paper presents a means of carrier phase cycle slip detection for an inertial-aided global positioning system (GPS), which is based on consideration of the satellite geometry. An integrated navigation solution incorporating a tightly coupled time differenced carrier phase (TDCP) and inertial navigation system (INS) is used to detect cycle slips. Cycle-slips are detected by comparing the satellite-difference (SD) and time-difference (TD) carrier phase measurements obtained from the GPS sa...

  15. Combining data from morphological traits and genetic markers to determine transmission cycles in the tape worm, Echinococcus granulosus.

    Science.gov (United States)

    Lymbery, A J

    1998-08-01

    Species of Echinococcus (Cestoda: Taeniidae) require 2 mammalian hosts to complete their life-cycle; a carnivorous definitive host, and a herbivorous or omnivorous intermediate host. For most species of Echinococcus, the definitive host range is restricted to 1 or a few species, but the intermediate host range is very broad. Programmes to control hydatid disease attempt to break the life-cycle of the parasite and their effectiveness is therefore enhanced by an understanding of local patterns of transmission. Although it is known that the rostellar hooks of protoscoleces may be influenced by the species of intermediate host in which they develop, the application of this knowledge to infer transmission cycles has been limited, because the intermediate host effect has not been isolated from other environmental and genetic components of phenotypic variance. This study presents a method for separating these potentially confounding genetic and environmental effects, by combining quantitative genetic analyses of hook traits with data on population structure from neutral genetic markers. The method was applied to 5 hook traits (hook number, total length of large hooks, blade length of large hooks, total length of small hooks, blade length of small hooks) measured on protoscoleces from 2 intermediate host types (sheep and macropod marsupials) in Australia. Although genetic variance was similar for all traits, they differed markedly in the extent of environmental variance attributed to development in different host types. Total length of small hooks was the trait most affected, with 49-60% of phenotypic variance being explained by environmental differences between intermediate host species. Blade length of small hooks was least affected, with none of the phenotypic variance due to intermediate host origin. These data suggest that hook measurements of adult worms from naturally infected definitive hosts could be used to determine the intermediate host species from which

  16. Comparison of Integrated Gasifier-Combined Cycle and AFB-steam turbine systems for industrial cogeneration

    Science.gov (United States)

    Nainiger, J. J.; Abbott, J. M.; Burns, R. K.

    1981-01-01

    In the cogeneration technology alternatives study (CTAS) a number of advanced coal fired systems were examined and systems using a integrated coal gasifier IGCC or a fluid bed combustor AFB were found to yield attractive cogeneration results in industrial cogeneration applications. A range of site requirements and cogeneration sizing strategies using ground rules based on CTAS were used in comparing an IGCC and an AFB. The effect of time variations in site requirements and the sensitivity to fuel and electricity price assumptions are examined. The economic alternatives of industrial or utility ownership are also considered. The results indicate that the IGCC system has potentially higher fuel and emission savings and could be an attractive option for utility ownership. The AFB steam turbine system has a potentially higher return on investment and could be attractive assuming industrial ownership.

  17. Performance evaluation of atmospheric biomass integrated gasifier combined cycle systems under different strategies for the use of low calorific gases

    International Nuclear Information System (INIS)

    Rodrigues, Monica; Walter, Arnaldo; Faaij, Andre

    2007-01-01

    This work aims at a performance evaluation of atmospheric BIGCC (biomass integrated gasifier combined cycle) systems operating under different strategies for the use of low calorific fuel in gas turbines. The fuel is a synthetic gas derived from gasification of sugar cane residues. Two analysed strategies for surge control on gas turbines originally designed for operation on natural gas are de-rating and air extraction from the compressor. Another strategy for use of biomass derived gas is the retrofit of a gas turbine through modification of the expander geometry. Three generic gas turbines, whose main parameters have been taken from off the shelf machines, are proposed as representative of certain classes of gas turbines. Results are compared to the hypothetical situation in which it is possible to accept any increase in gas turbine pressure ratio. According to the results, de-rating is the worst surge control strategy, both from the point of view of power production and thermal efficiency. Conversely, results showed considerable gains that can be obtained on cycle power production when the gas turbine expander is modified. Additionally, an overview of issues concerning the suitability of sugar cane residues (bagasse and trash) for the production of gasified gas and its use in BIGCC plants is presented

  18. A Co-Powered Biomass and Concentrated Solar Power Rankine Cycle Concept for Small Size Combined Heat and Power Generation

    Directory of Open Access Journals (Sweden)

    Eileen Tortora

    2013-03-01

    Full Text Available The present work investigates the matching of an advanced small scale Combined Heat and Power (CHP Rankine cycle plant with end-user thermal and electric load. The power plant consists of a concentrated solar power field co-powered by a biomass furnace to produce steam in a Rankine cycle, with a CHP configuration. A hotel was selected as the end user due to its high thermal to electric consumption ratio. The power plant design and its operation were modelled and investigated by adopting transient simulations with an hourly distribution. The study of the load matching of the proposed renewable power technology and the final user has been carried out by comparing two different load tracking scenarios, i.e., the thermal and the electric demands. As a result, the power output follows fairly well the given load curves, supplying, on a selected winter day, about 50 GJ/d of thermal energy and the 6 GJ/d of electric energy, with reduced energy dumps when matching the load.

  19. Economic assessment of combined cycle gas turbines in Australia Some effects of microeconomic reform and technological change

    International Nuclear Information System (INIS)

    Naughten, Barry

    2003-01-01

    Australian electricity markets and natural gas markets are undergoing rapid reform. Choosing among electricity generation modes is a key issue. Such choices are affected by expectations about the future structure of these markets and future technologies, and how they affect costs and emissions. In the research reported in this paper, the MARKAL model of the Australian energy system is used to evaluate the competitive position of natural gas fired combined cycle gas turbines (CCGTs) in the energy sector as a whole. Competing in the sector are large-scale electricity generation technologies such as refurbished existing coal fired stations and advanced forms of coal fired generation. The modelling incorporates new data on electricity supply technologies and options

  20. Variable geometry gas turbines for improving the part-load performance of marine combined cycles - Gas turbine performance

    DEFF Research Database (Denmark)

    Haglind, Fredrik

    2010-01-01

    The part-load performance of gas and steam turbine combined cycles intended for naval use is of great importance, and it is influenced by the gas turbine configuration and load control strategy. This paper is aimed at quantifying the effects of variable geometry on the gas turbine part...... of various components within gas turbines. Two different gas turbine configurations are studied, a two-shaft aero-derivative configuration and a single-shaft industrial configuration. When both gas turbine configurations are running in part-load using fuel flow control, the results indicate better part......-load performance for the two-shaft gas turbine. Reducing the load this way is accompanied by a much larger decrease in exhaust gas temperature for the single-shaft gas turbine than for the two-shaft configuration. As used here, the results suggest that variable geometry generally deteriorates the gas turbine part...

  1. The graded cycling test combined with the talk test is reliable for patients with ischemic heart disease

    DEFF Research Database (Denmark)

    Nielsen, Susanne Grøn; Buus, Lise; Hage, Tine

    2014-01-01

    PURPOSE: To assess relative reliability and measurement error of the Graded Cycling Test (GCT) with the Talk Test (TT) for patients with cardiac disease. METHODS: Patients (N = 64; women, n = 30) with ischemic heart disease performed the GCT with the TT twice in 1 day. Every minute the patient.......81 and 0.88. SEM95 ranged between 17.2 and 18.3 watts (W), with corresponding SRD values between 24.4 and 25.9 W for the patient ratings. The PT ratings ranged between 15.8 and 21.4 W (SEM95) and between 22.3 and 30.3 W (SRD). CONCLUSIONS: The TT, combined with the GCT, was well tolerated by patients...

  2. Thermodynamic analysis and thermoeconomic optimization of a dual pressure combined cycle power plant with a supplementary firing unit

    International Nuclear Information System (INIS)

    Ahmadi, Pouria; Dincer, Ibrahim

    2011-01-01

    Research highlights: → A comprehensive study on a dual pressure combined cycle power plant with supplementary firing unit. → A new integrated thermodynamic modeling and thermoeconomic optimization. → Better performance assessment. → Utilization genetic algorithms to improve efficiency and reduce exergy destructions and cost. -- Abstract: In this paper, a combined cycle power plant (CCPP) with a supplementary firing system is first thermodynamically analyzed through energy and exergy. The optimal design of operating parameters of the plant is then performed by defining an objective function and applying a generic algorithm (GA) type optimization method. In order to optimally find the design parameters, a thermo-economic method is employed. An objective function representing the total cost of the plant in terms of dollar per second is defined as the sum of the operating cost related to the fuel consumption and the capital investment for equipment purchase and maintenance costs. Subsequently, different parts of the objective function are expressed in terms of decision variables. Finally, the optimal values of decision variables are obtained by minimizing the objective function using a GA. Moreover, the influences of changes in the demanded power and fuel cost are studied by considering three different output powers (i.e., 160, 180 and 200 MW). To validate the present model, the results of the present simulation code are compared with the actual data. The results show that the average difference between the model results and the actual data is about 1.41%. Moreover, various cases are investigated to determine how to decrease the objective function (cost, mass flowrate, etc.) for the optimized design and operating parameters (fuel cost, power output, etc.).

  3. Coal diesel combined-cycle project. Annual report, January 1996--January 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The Clean Coal Diesel project will demonstrate a new Clean Coal Technology that has technical, economic and environmental advantages over conventional power generating methods. This innovative technology enables utilization of coal-based fuel in large-bore, medium-speed, diesel engines. Modular power generating applications in the 10 to 100 megawatt size range are the target applications. The University of Alaska campus in Fairbanks, Alaska, is the project`s host site. At this location, the University will construct and operate the Clean Coal Diesel System, which will serve as a 6.2 MW diesel powerplant addition. The University will also assemble and operate a 5-ton per hour coal-water fuel processing plant. The plant will utilize local coal, brought by truck from Usibelli`s mine in Healey, AK. The estimated performance characteristics of the mature commercial embodiment of the Clean Coal Diesel, if achieved, will make this technology quite competitive: 48% efficiency; $1,300/kW installed cost; and emission levels controlled to 50--70% below New Source Performance Standards. Specific objectives are to demonstrate that the Coal Diesel Technology: is durable and can operate 6,000 hours in a realistic commercial setting; will meet efficiency targets; can effectively control criteria pollutants to levels that are well below anticipated standards, as well as reduce greenhouse gas emissions; and can accommodate substantial power demand swings.

  4. Advanced Monitoring to Improve Combustion Turbine/Combined Cycle Reliability, Availability & Maintainability

    Energy Technology Data Exchange (ETDEWEB)

    Leonard Angello

    2005-09-30

    Power generators are concerned with the maintenance costs associated with the advanced turbines that they are purchasing. Since these machines do not have fully established Operation and Maintenance (O&M) track records, power generators face financial risk due to uncertain future maintenance costs. This risk is of particular concern, as the electricity industry transitions to a competitive business environment in which unexpected O&M costs cannot be passed through to consumers. These concerns have accelerated the need for intelligent software-based diagnostic systems that can monitor the health of a combustion turbine in real time and provide valuable information on the machine's performance to its owner/operators. EPRI, Impact Technologies, Boyce Engineering, and Progress Energy have teamed to develop a suite of intelligent software tools integrated with a diagnostic monitoring platform that, in real time, interpret data to assess the 'total health' of combustion turbines. The 'Combustion Turbine Health Management System' (CTHMS) will consist of a series of 'Dynamic Link Library' (DLL) programs residing on a diagnostic monitoring platform that accepts turbine health data from existing monitoring instrumentation. CTHMS interprets sensor and instrument outputs, correlates them to a machine's condition, provide interpretative analyses, project servicing intervals, and estimate remaining component life. In addition, the CTHMS enables real-time anomaly detection and diagnostics of performance and mechanical faults, enabling power producers to more accurately predict critical component remaining useful life and turbine degradation.

  5. Simulated performance of biomass gasification based combined power and refrigeration plant for community scale application

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, S., E-mail: suman.mech09@gmail.com [Department of Mechanical Engineering, NIT, Agarpara, Kolkata – 700109, West Bengal (India); Mondal, P., E-mail: mondal.pradip87@gmail.com; Ghosh, S., E-mail: sudipghosh.becollege@gmail.com [Department of Mechanical Engineering, IIEST, Shibpur, Howrah – 711103, West Bengal (India)

    2016-07-12

    Thermal performance analysis and sizing of a biomass gasification based combined power and refrigeration plant (CPR) is reported in this study. The plant is capable of producing 100 kWe of electrical output while simultaneously producing a refrigeration effect, varying from 28-68 ton of refrigeration (TR). The topping gas turbine cycle is an indirectly heated all-air cycle. A combustor heat exchanger duplex (CHX) unit burns producer gas and transfer heat to air. This arrangement avoids complex gas cleaning requirements for the biomass-derived producer gas. The exhaust air of the topping GT is utilized to run a bottoming ammonia absorption refrigeration (AAR) cycle via a heat recovery steam generator (HRSG), steam produced in the HRSG supplying heat to the generator of the refrigeration cycle. Effects of major operating parameters like topping cycle pressure ratio (r{sub p}) and turbine inlet temperature (TIT) on the energetic performance of the plant are studied. Energetic performance of the plant is evaluated via energy efficiency, required biomass consumption and fuel energy savings ratio (FESR). The FESR calculation method is significant for indicating the savings in fuel of a combined power and process heat plant instead of separate plants for power and process heat. The study reveals that, topping cycle attains maximum power efficiency of 30%in pressure ratio range of 8-10. Up to a certain value of pressure ratio the required air flow rate through the GT unit decreases with increase in pressure ratio and then increases with further increase in pressure ratio. The capacity of refrigeration of the AAR unit initially decreases up to a certain value of topping GT cycle pressure ratio and then increases with further increase in pressure ratio. The FESR is found to be maximized at a pressure ratio of 9 (when TIT=1100°C), the maximum value being 53%. The FESR is higher for higher TIT. The heat exchanger sizing is also influenced by the topping cycle pressure ratio

  6. Thermochemical recuperative combined cycle with methane-steam reforming combustion; Tennengasu kaishitsu nensho ni yoru konbaindo saikuru hatsuden no kokoritsuka oyobi denryoku fuka heijunka taio

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, R.; Essaki, K.; Tsutsumi, A. [The University of Tokyo, Tokyo (Japan). Dept. of Chemical System Engineering; Kaganoi, S.; Kurimura, H. [Teikoku Sekiyu Co., Tokyo (Japan); Sasaki, T.; Ogawa, T. [Toshiba Co., Tokyo (Japan)

    2000-03-10

    Thermochemical recuperative combined cycles with methane-steam reforming are proposed for improving their thermal efficiency and for peak-load leveling. For targeting higher thermal efficiency, a cycle with methane-steam reforming reaction heated by gas turbine exhaust was analyzed. The inlet temperature of gas turbine was set at 1,350 degree C. Low-pressure steam extracted from a steam turbine is mixed with methane, and then this mixture is heated by part of the gas turbine exhaust to promote a reforming reaction. The rest of the exhaust heat is used to produce steam, which drives steam turbines to generate electricity. The effect of steam-to-methane ratio (S/C) on thermal efficiency of the cycle, as well as on methane conversion, is investigated by using the ASPEN Plus process simulator. The methane feed rate was fixed at constant and S/C ratio was varied from 2.25 to 4.75. Methane conversion shows an increasing trend toward the ratio and has a maximum value of 17.9 % at S/C=4.0. Thermal efficiency for the system is about 51 % higher than that calculated for a conventional 1,300 degree C class combined cycle under similar conditions. A thermochemical recuperative combined cycle is designed for peak-load leveling. In night-time operation from 20 : 00 to 8 : 00 it stores hydrogen produced by methane steam reforming at S/C=3.9 to save power generation. The gas turbine inlet temperature is 1,330 degree C. In daytime operation from 8 : 00 to 20 : 00 the chemically recuperated combined cycle operated at S/C=2.0 is driven by the mixture of a combined cycle operated at constant load with the same methane feed rate, whereas daytime operation generated power 1.26 times larger than that of the combined cycle. (author)

  7. Macro-fiber composites performance under thermal cycling for impedance-based SHM applications

    Science.gov (United States)

    Faria, Cassio T.; Owen, Robert B.; Inman, Daniel J.

    2014-03-01

    This work focuses on investigating the effects of thermal cycles in the impedance-based damage detection performance of Macro-Fiber Composites (MFC). A host structure with an MFC bonded to its surface is submitted to a 90 minutes temperature cycle that varies from -20°C to 65° C. After each cycle the electrical impedance of the test sample is measured with and without the presence of a representative damage (an added mass). The results indicate that the thermal cycling affects the smart device by changing its impedance profile, a phenomenon that should be taken into account in damage detection algorithms.

  8. Combine harvester monitor system based on wireless sensor network

    Science.gov (United States)

    A measurement method based on Wireless Sensor Network (WSN) was developed to monitor the working condition of combine harvester for remote application. Three JN5139 modules were chosen for sensor data acquisition and another two as a router and a coordinator, which could create a tree topology netwo...

  9. Combining Document-and Paragraph-Based Entity Ranking

    NARCIS (Netherlands)

    Rode, H.; Serdyukov, Pavel; Hiemstra, Djoerd

    2008-01-01

    We study entity ranking on the INEX entity track and pro- pose a simple graph-based ranking approach that enables to combine scores on document and paragraph level. The com- bined approach improves the retrieval results not only on the INEX testset, but similarly on TREC’s expert finding task.

  10. Knowledge base combinations and innovation performance in Swedish regions

    Czech Academy of Sciences Publication Activity Database

    Grillitsch, M.; Martin, R.; Srholec, Martin

    2017-01-01

    Roč. 93, č. 5 (2017), s. 458-479 ISSN 0013-0095 Institutional support: RVO:67985998 Keywords : knowledge base * knowledge combination * region Subject RIV: AH - Economics OBOR OECD: Applied Economics, Econometrics Impact factor: 5.344, year: 2016

  11. Knowledge base combinations and innovation performance in Swedish regions

    Czech Academy of Sciences Publication Activity Database

    Grillitsch, M.; Martin, R.; Srholec, Martin

    2017-01-01

    Roč. 93, č. 5 (2017), s. 458-479 ISSN 0013-0095 Institutional support: Progres-Q24 Keywords : knowledge base * knowledge combination * region Subject RIV: AH - Economics OBOR OECD: Applied Economics, Econometrics Impact factor: 5.344, year: 2016

  12. Development of web based performance analysis program for nuclear power plant turbine cycle

    International Nuclear Information System (INIS)

    Park, Hoon; Yu, Seung Kyu; Kim, Seong Kun; Ji, Moon Hak; Choi, Kwang Hee; Hong, Seong Ryeol

    2002-01-01

    Performance improvement of turbine cycle affects economic operation of nuclear power plant. We developed performance analysis system for nuclear power plant turbine cycle. The system is based on PTC (Performance Test Code), that is estimation standard of nuclear power plant performance. The system is developed using Java Web-Start and JSP(Java Server Page)

  13. LIFE CYCLE ASSESSMENT FOR OIL PALM BASED PLYWOOD: A GATE-TO-GATE CASE STUDY

    OpenAIRE

    M. Shamim Ahmad; Vijaya Subramaniam; Halimah Mohammad; Anis Mokhtar; B. S. Ismail

    2014-01-01

    Life Cycle Assessment (LCA) is an important tool for identifying potential environmental impacts associated with the production of palm based plywood. This study is to make available the life cycle inventory for gate-to-gate data so that the environmental impact posed by oil palm based plywood production can be assessed. Conducting an LCA on the palm based plywood that are derived from the wastes of the oil palm industry is a first step towards performing green environmental product. Therefor...

  14. Evaluating urban form and location effects on cycling based on Danish micro-data

    DEFF Research Database (Denmark)

    Nielsen, Thomas Alexander Sick; Olafsson, Anton Stahl; Carstensen, Trine Agervig

    Extended abstract The paper analyses the environmental correlates of cycling based on Danish transportation and urban form micro-data. Established walkability factors such as density, connectivity and diversity are related to cycling, but access to retail concentrations/centers, public...... transportation level-of-service, as well a competition between walking and cycling depending on environmental features can be added Attractive conditions for using public transportation or walking relate to less cycling. Highly relevant in the context of cycling promotion the results points to some opposite...... can be seen as a potential means to reduce congestion and increase the sustainability of transportation, but also as a means to increase physical activity and public health. Consequently the factors conditioning cycling have received increasing attention in public policy as well as in research...

  15. An Effective Combined Feature For Web Based Image Retrieval

    Directory of Open Access Journals (Sweden)

    H.M.R.B Herath

    2015-08-01

    Full Text Available Abstract Technology advances as well as the emergence of large scale multimedia applications and the revolution of the World Wide Web has changed the world into a digital age. Anybody can use their mobile phone to take a photo at any time anywhere and upload that image to ever growing image databases. Development of effective techniques for visual and multimedia retrieval systems is one of the most challenging and important directions of the future research. This paper proposes an effective combined feature for web based image retrieval. Frequently used colour and texture features are explored in order to develop a combined feature for this purpose. Widely used three colour features Colour moments Colour coherence vector and Colour Correlogram and three texture features Grey Level Co-occurrence matrix Tamura features and Gabor filter were analyzed for their performance. Precision and Recall were used to evaluate the performance of each of these techniques. By comparing precision and recall values the methods that performed best were taken and combined to form a hybrid feature. The developed combined feature was evaluated by developing a web based CBIR system. A web crawler was used to first crawl through Web sites and images found in those sites are downloaded and the combined feature representation technique was used to extract image features. The test results indicated that this web system can be used to index web images with the combined feature representation schema and to find similar images. Random image retrievals using the web system shows that the combined feature can be used to retrieve images belonging to the general image domain. Accuracy of the retrieval can be noted high for natural images like outdoor scenes images of flowers etc. Also images which have a similar colour and texture distribution were retrieved as similar even though the images were belonging to deferent semantic categories. This can be ideal for an artist who wants

  16. Environmental impacts of combining pig slurry acidification and separation under different regulatory regimes - A life cycle assessment.

    Science.gov (United States)

    Ten Hoeve, Marieke; Gómez-Muñoz, Beatriz; Jensen, Lars S; Bruun, Sander

    2016-10-01

    Global livestock production is increasing rapidly, leading to larger amounts of manure and environmental impacts. Technologies that can be applied to treat manure in order to decrease certain environmental impacts include separation and acidification. In this study, a life cycle assessment was used to investigate the environmental effects of slurry acidification and separation, and whether there were synergetic environmental benefits to combining these technologies. Furthermore, an analysis was undertaken into the effect of implementing regulations restricting the P application rate to soils on the environmental impacts of the technologies. The impact categories analysed were climate change, terrestrial, marine and freshwater eutrophication, fossil resource depletion and toxicity potential. In-house slurry acidification appeared to be the most beneficial scenario under both N and P regulations. Slurry separation led to a lower freshwater eutrophication potential than the other scenarios in which N regulations alone were in force, while these environmental benefits disappeared after implementation of stricter P regulations. With N regulations alone, there was a synergetic positive effect of combining in-house acidification and separation on marine eutrophication potential compared to these technologies individually. The model was sensitive to the chosen ammonia emission coefficients and to the choice of inclusion of indirect nitrous oxide emissions, since scenarios changed ranking for certain impact categories. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Combining ability of elephant grass based on nutritional characters

    Directory of Open Access Journals (Sweden)

    Vanessa Quitete Ribeiro da Silva

    2014-03-01

    Full Text Available The objective of the work was to evaluate the effects of general combining ability (CGC of the parents and specific combining ability (CEC in the elephant grass hybrids by diallel analysis adapted to partial diallel crosses based on nutritional characters. Sixteen hybrids and eight parents in a randomized block design with three replications were evaluated. The study considered percentage of dry matter (%DM, ash (%ASH, crude protein (%CP and neutral detergent fiber (NDF. There were significant differences among genotypes for the traits evaluated, with a predominance of dominance gene effect. Based on CGC, the best parents were Taiwan A-144, Vruckwona Africana e Taiwan A-146. The best intersections based on CEC were Taiwan A-144 x Taiwan A-146, Vruckwona Africana x Taiwan A-146, Vruckwona Africana x Mercker S.E.A., Vruckwona Africana x Napier nº2 e Pusa Napier nº2 x Mercker Santa Rita.

  18. Microbial nitrogen cycling response to forest-based bioenergy production.

    Science.gov (United States)

    Minick, Kevan J; Strahm, Brian D; Fox, Thomas R; Sucre, Eric B; Leggett, Zakiya H

    2015-12-01

    Concern over rising atmospheric CO2 and other greenhouse gases due to fossil fuel combustion has intensified research into carbon-neutral energy production. Approximately 15.8 million ha of pine plantations exist across the southeastern United States, representing a vast land area advantageous for bioenergy production without significant landuse change or diversion of agricultural resources from food production. Furthermore, intercropping of pine with bioenergy grasses could provide annually harvestable, lignocellulosic biomass feedstocks along with production of traditional wood products. Viability of such a system hinges in part on soil nitrogen (N) availability and effects of N competition between pines and grasses on ecosystem productivity. We investigated effects of intercropping loblolly pine (Pinus taeda) with switchgrass (Panicum virgatum) on microbial N cycling processes in the Lower Coastal Plain of North Carolina, USA. Soil samples were collected from bedded rows of pine and interbed space of two treatments, composed of either volunteer native woody and herbaceous vegetation (pine-native) or pure switchgrass (pine-switchgrass) in interbeds. An in vitro 15N pool-dilution technique was employed to quantify gross N transformations at two soil depths (0-5 and 5-15 cm) on four dates in 2012-2013. At the 0-5 cm depth in beds of the pine-switchgrass treatment, gross N mineralization was two to three times higher in November and February compared to the pine-native treatment, resulting in increased NH4(+) availability. Gross and net nitrification were also significantly higher in February in the same pine beds. In interbeds of the pine-switchgrass treatment, gross N mineralization was lower from April to November, but higher in February, potentially reflecting positive effects of switchgrass root-derived C inputs during dormancy on microbial activity. These findings indicate soil N cycling and availability has increased in pine beds of the pine

  19. GPS Cycle Slip Detection Considering Satellite Geometry Based on TDCP/INS Integrated Navigation.

    Science.gov (United States)

    Kim, Younsil; Song, Junesol; Kee, Changdon; Park, Byungwoon

    2015-09-30

    This paper presents a means of carrier phase cycle slip detection for an inertial-aided global positioning system (GPS), which is based on consideration of the satellite geometry. An integrated navigation solution incorporating a tightly coupled time differenced carrier phase (TDCP) and inertial navigation system (INS) is used to detect cycle slips. Cycle-slips are detected by comparing the satellite-difference (SD) and time-difference (TD) carrier phase measurements obtained from the GPS satellites with the range estimated by the integrated navigation solution. Additionally the satellite geometry information effectively improves the range estimation performance without a hardware upgrade. And the covariance obtained from the TDCP/INS filter is used to compute the threshold for determining cycle slip occurrence. A simulation and the results of a vehicle-based experiment verify the cycle slip detection performance of the proposed algorithm.

  20. GPS Cycle Slip Detection Considering Satellite Geometry Based on TDCP/INS Integrated Navigation

    Directory of Open Access Journals (Sweden)

    Younsil Kim

    2015-09-01

    Full Text Available This paper presents a means of carrier phase cycle slip detection for an inertial-aided global positioning system (GPS, which is based on consideration of the satellite geometry. An integrated navigation solution incorporating a tightly coupled time differenced carrier phase (TDCP and inertial navigation system (INS is used to detect cycle slips. Cycle-slips are detected by comparing the satellite-difference (SD and time-difference (TD carrier phase measurements obtained from the GPS satellites with the range estimated by the integrated navigation solution. Additionally the satellite geometry information effectively improves the range estimation performance without a hardware upgrade. And the covariance obtained from the TDCP/INS filter is used to compute the threshold for determining cycle slip occurrence. A simulation and the results of a vehicle-based experiment verify the cycle slip detection performance of the proposed algorithm.

  1. Multi-criteria optimization of on-site heating, cooling and power generation with solid oxide fuel cell-gas turbine combined cycle units

    Energy Technology Data Exchange (ETDEWEB)

    K. Tanaka; M. Burer; D. Favrat; K. Yamada [UMIST, Manchester (United Kingdom). Tyndall Centre for Climate Change Research

    2003-07-01

    The implementation of integrated energy systems within urban areas is a promising CO{sub 2} emissions abatement measure. In this paper on-site heating, cooling and power generation based on a solid oxide fuel cell and gas turbine (SOFC-GT) combined cycle unit associated with a compression chiller and additional boilers has been considered from the viewpoints of cost and CO{sub 2} emissions. Physical and costing modelling of such a unit has been integrated within a new multi-criteria evolutionary algorithm for an assessment of the economic and environmental performances associated with optimal design and operation, for typical requirements of large office buildings in Tokyo. 9 refs., 8 figs., 2 tabs.

  2. Biology-based combined-modality radiotherapy: workshop report

    International Nuclear Information System (INIS)

    Mason, Kathryn A.; Komaki, Ritsuko; Cox, James D.; Milas, Luka

    2001-01-01

    Purpose: The purpose of this workshop summary is to provide an overview of preclinical and clinical data on combined-modality radiotherapy. Methods and Materials: The 8th Annual Radiation Workshop at Round Top was held April 13-16, 2000 at the International Festival Institute (Round Top, TX). Results: Presentations by 30 speakers (from Germany, Netherlands, Australia, England, and France along with U.S. participants and M. D. Anderson Cancer Center faculty) formed the framework for discussions on the current status and future perspectives of biology-based combined-modality radiotherapy. Conclusion: Cellular and molecular pathways available for radiation modification by chemical and biologic agents are numerous, providing new opportunities for translational research in radiation oncology and for more effective combined-modality treatment of cancer

  3. Extended cycle combined oral contraceptives and prophylactic frovatriptan during the hormone-free interval in women with menstrual-related migraines.

    Science.gov (United States)

    Coffee, Andrea L; Sulak, Patricia J; Hill, Alexandria J; Hansen, Darci J; Kuehl, Thomas J; Clark, Jeffrey W

    2014-04-01

    Migraine headaches are a significant problem for American women with many of them suffering from headaches around the time of their menstrual cycle. Women taking oral contraceptives in the standard 21/7 cycle regimen often suffer from headaches around the time of the hormone free intervals (HFIs) as well. Extended oral contraceptive regimens have been shown to decrease the frequency, but not eliminate these headaches. This study is a double-blind, randomized, placebo-controlled pilot study of participants with menstrual-related migraines (MRMs) who were initiated on extended combined oral contraceptives and given frovatriptan prophylactically during HFIs. Participants having spontaneous menstrual cycles or taking daily combined oral contraceptives in a 21/7 regimen with MRMs were placed on a contraceptive containing levonorgestrel and ethinyl estradiol. Analyses compared headache scores during pre-study baseline cycles to those in a 168-day extended regimen with placebo versus frovatriptan treatments during HFIs. Daily headache scores decreased (p=0.034) from 1.29 ± 0.10 during pre-study cycles to 1.10 ± 0.14 during extended combined oral contraceptive use. Frovatriptan blocked the increase in headache score over the placebo during HFIs. However, following the withdrawal of frovatriptan, headache scores increased (p>0.01) despite resuming combined oral contraceptive use. Extended combined oral contraceptive regimen reduces MRM severity. Frovatriptan prevents headaches during HFIs, but is associated with new headache symptoms when withdrawn.

  4. Comparative 4-E analysis of a bottoming pure NH3 and NH3-H2O mixture based power cycle for condenser waste heat recovery

    Science.gov (United States)

    Khankari, Goutam; Karmakar, Sujit

    2017-06-01

    This paper proposes a comparative performance analysis based on 4-E (Energy, Exergy, Environment, and Economic) of a bottoming pure Ammonia (NH3) based Organic Rankine Cycle (ORC) and Ammonia-water (NH3-H2O) based Kalina Cycle System 11(KCS 11) for additional power generation through condenser waste heat recovery integrated with a conventional 500MWe Subcritical coal-fired thermal power plant. A typical high-ash Indian coal is used for the analysis. The flow-sheet computer programme `Cycle Tempo' is used to simulate both the cycles for thermodynamic performance analysis at different plant operating conditions. Thermodynamic analysis is done by varying different NH3 mass fraction in KCS11 and at different turbine inlet pressure in both ORC and KCS11. Results show that the optimum operating pressure of ORC and KCS11 with NH3 mass fraction of 0.90 are about 15 bar and 11.70 bar, respectively and more than 14 bar of operating pressure, the plant performance of ORC integrated power plant is higher than the KCS11 integrated power plant and the result is observed reverse below this pressure. The energy and exergy efficiencies of ORC cycle are higher than the KCS11 by about 0.903 % point and 16.605 % points, respectively under similar saturation vapour temperature at turbine inlet for both the cycles. Similarly, plant energy and exergy efficiencies of ORC based combined cycle power plant are increased by 0.460 % point and 0.420 % point, respectively over KCS11 based combined cycle power plant. Moreover, the reduction of CO2 emission in ORC based combined cycle is about 3.23 t/hr which is about 1.5 times higher than the KCS11 based combined cycle power plant. Exergy destruction of the evaporator in ORC decreases with increase in operating pressure due to decrease in temperature difference of heat exchanging fluids. Exergy destruction rate in the evaporator of ORC is higher than KCS11 when the operating pressure of ORC reduces below 14 bar. This happens due to variable

  5. Numerical analysis of radial inward flow turbine for CO2 based closed loop Brayton cycle

    Science.gov (United States)

    Kisan, Jadhav Amit; Govardhan, M.

    2017-06-01

    Last few decades have witnessed a phenomenal growth in the demand for power, which has driven the suppliers to find new sources of energy and increase the efficiency of power generation process. Power generation cycles are either steam based Rankine cycle or closed loop Brayton cycles providing an efficiency of 30 to 40%. An upcoming technology in this regard is the CO2 based Brayton cycle operating near the critical region which has applications in vast areas. Power generation of CO2 based Brayton cycle can vary from few kilowatts for waste heat recovery to hundreds of megawatts in sodium cooled fast reactors. A CO2 based Brayton cycle is being studied for power generation especially in mid-sized concentrated solar power plants by numerous research groups around the world. One of the main components of such a setting is its turbine. Simulating the flow conditions inside the turbine becomes very crucial in order to accurately predict the performance of the system. The flow inside radial inflow turbine is studied at various inlet temperatures and mass flow rates in order to predict the behavior of the turbine under various boundary conditions. The performance investigation of the turbine system is done on the basis of parameters such as total efficiency, pressure ratio, and power coefficient. Effect of different inlet stagnation temperature and exit mass flow rates on these parameters is also studied. Results obtained are encouraging for the use of CO2 as working fluid in Brayton cycle.

  6. Shannon Entropy-Based Prediction of Solar Cycle 25

    Science.gov (United States)

    Kakad, Bharati; Kakad, Amar; Ramesh, Durbha Sai

    2017-07-01

    A new model is proposed to forecast the peak sunspot activity of the upcoming solar cycle (SC) using Shannon entropy estimates related to the declining phase of the preceding SC. Daily and monthly smoothed international sunspot numbers are used in the present study. The Shannon entropy is the measure of inherent randomness in the SC and is found to vary with the phase of an SC as it progresses. In this model each SC with length T_{cy} is divided into five equal parts of duration T_{cy}/5. Each part is considered as one phase, and they are sequentially termed P1, P2, P3, P4, and P5. The Shannon entropy estimates for each of these five phases are obtained for the nth SC starting from n=10 - 23. We find that the Shannon entropy during the ending phase (P5) of the nth SC can be efficiently used to predict the peak smoothed sunspot number of the (n+1)th SC, i.e. S_{max}^{n+1}. The prediction equation derived in this study has a good correlation coefficient of 0.94. A noticeable decrease in entropy from 4.66 to 3.89 is encountered during P5 of SCs 22 to 23. The entropy value for P5 of the present SC 24 is not available as it has not yet ceased. However, if we assume that the fall in entropy continues for SC 24 at the same rate as that for SC 23, then we predict the peak smoothed sunspot number of 63±11.3 for SC 25. It is suggested that the upcoming SC 25 will be significantly weaker and comparable to the solar activity observed during the Dalton minimum in the past.

  7. Performance of ammonia–water based cycles for power generation from low enthalpy heat sources

    International Nuclear Information System (INIS)

    Mergner, Hanna; Weimer, Thomas

    2015-01-01

    Cost efficient power generation from low temperature heat sources requires an optimal usage of the available heat. In addition to the ORC (Organic Rankine Cycles), cycles with ammonia and water as working fluid show promising results regarding efficiency. Due to their non-isothermal phase change, mixtures can adapt well to a liquid heat source temperature profile and reduce the exergetic losses. In this analysis thermodynamic calculations on the layouts of two existing ammonia–water cycles are compared: a geothermal power plant based on a Siemens’ patent and a modified lab plant based on a patent invented by Kalina (KCS-34). The difference between the two cycles is the position of the internal heat recovery. Cycle simulations were carried out at defined boundary conditions in order to identify optimal operation parameters. For the selected heat source of 393.15 K (hot water) the ammonia mass fraction between 80% and 90% results in the best performance in both configurations. In general, the layout of Siemens achieves a slightly better efficiency compared to the KCS-34. Compared to an ORC using R245fa as working fluid, the exergetic efficiency can be increased by the ammonia/water based cycles by approximately 25%. - Highlights: • Two NH 3 /H 2 O based cycles based on existing plants are analyzed and compared. • A simple KCS-34 focuses on a high enthalpy difference at the turbine. • The Kalina cycle of a Siemens patent KC SG1 runs on a high vapor mass flow. • The layout of the KC SG1 shows slightly better results compared to the KCS-34. • NH 3 /H 2 O cycles show an efficiency increase compared to a regular ORC with R245fa

  8. Prediction of solar cycle 24 based on the Gnevyshev-Ohl-Kopecky rule and the three-cycle periodicity scheme

    Science.gov (United States)

    Kane, R. P.

    2008-10-01

    An examination of the maximum yearly values of the conventional sunspot number Rz of all cycles revealed fluctuations of various intervals in the high periodicity region (exceeding 11 years), namely 2 cycles (Hale, 22 years), 3 cycles (TRC, three-cycle) and longer intervals. The 2-cycle spacings had the smallest amplitudes. According to the G-O (Gnevyshev-Ohl) rule (Gnevyshev and Ohl, 1948), the even-numbered series of the maxima of annual mean Wolf sunspot numbers Rz are followed by higher amplitude odd-numbered series. Kopecky (1950) generalized this relation to annual mean Wolf numbers corresponding to equivalent phases of the adjacent even-odd 11-year cycles. Therefore, we would call it the G-O-K rule. For the data of 28 cycles (cycle -4 to cycle 23), it was found that four pairs (~29%) from the fourteen even-odd pairs showed failure of the G-O-K rule. In the remaining ten pairs, the magnitudes of the odd cycles were well-correlated with the magnitudes of the preceding even cycles, but it was impossible to tell whether it would be a normal pair following the G-O-K rule or a possible case of failure. A much stronger sequence was the three-cycle sequence (TRC, low, high, higher). The 2-cycle oscillations were embedded into the TRC until the G-O-K rule failures occurred as in cycle 23. The patterns of cycle 17 (low), 18 (high), 19 (higher); 20 (low), 21 (high), 22 (higher) were noticed and used by Ahluwalia (1995, 1998) to predict a low value for cycle 23, which was accurate. However, in the earlier data, the preceding sequence (14, 15, 16) was rather uncertain, and before that for seven cycles (cycles 8-14), there were no TRC sequences at all. During the twelve cycles -4 to 7, there were only three isolated TRC sequences (one doubtful). In view of this chequered history of TRC, it is doubtful whether the present TRC pattern (cycles 17 23) would persist in the near future. Spectral analysis showed that in the first half (cycles -4 to 9), larger periodicities

  9. Prediction of solar cycle 24 based on the Gnevyshev-Ohl-Kopecky rule and the three-cycle periodicity scheme

    Directory of Open Access Journals (Sweden)

    R. P. Kane

    2008-10-01

    Full Text Available An examination of the maximum yearly values of the conventional sunspot number Rz of all cycles revealed fluctuations of various intervals in the high periodicity region (exceeding 11 years, namely 2 cycles (Hale, 22 years, 3 cycles (TRC, three-cycle and longer intervals. The 2-cycle spacings had the smallest amplitudes. According to the G-O (Gnevyshev-Ohl rule (Gnevyshev and Ohl, 1948, the even-numbered series of the maxima of annual mean Wolf sunspot numbers Rz are followed by higher amplitude odd-numbered series. Kopecky (1950 generalized this relation to annual mean Wolf numbers corresponding to equivalent phases of the adjacent even-odd 11-year cycles. Therefore, we would call it the G-O-K rule. For the data of 28 cycles (cycle −4 to cycle 23, it was found that four pairs (~29% from the fourteen even-odd pairs showed failure of the G-O-K rule. In the remaining ten pairs, the magnitudes of the odd cycles were well-correlated with the magnitudes of the preceding even cycles, but it was impossible to tell whether it would be a normal pair following the G-O-K rule or a possible case of failure. A much stronger sequence was the three-cycle sequence (TRC, low, high, higher. The 2-cycle oscillations were embedded into the TRC until the G-O-K rule failures occurred as in cycle 23. The patterns of cycle 17 (low, 18 (high, 19 (higher; 20 (low, 21 (high, 22 (higher were noticed and used by Ahluwalia (1995, 1998 to predict a low value for cycle 23, which was accurate. However, in the earlier data, the preceding sequence (14, 15, 16 was rather uncertain, and before that for seven cycles (cycles 8-14, there were no TRC sequences at all. During the twelve cycles −4 to 7, there were only three isolated TRC sequences (one doubtful. In view of this chequered history of TRC, it is doubtful whether the present TRC pattern (cycles 17–23 would persist in the near future. Spectral analysis showed that in the first half (cycles −4 to 9, larger

  10. NEPA, a fixed oral combination of netupitant and palonosetron, improves control of chemotherapy-induced nausea and vomiting (CINV) over multiple cycles of chemotherapy: results of a randomized, double-blind, phase 3 trial versus oral palonosetron.

    Science.gov (United States)

    Aapro, Matti; Karthaus, Meinolf; Schwartzberg, Lee; Bondarenko, Igor; Sarosiek, Tomasz; Oprean, Cristina; Cardona-Huerta, Servando; Hansen, Vincent; Rossi, Giorgia; Rizzi, Giada; Borroni, Maria Elisa; Rugo, Hope

    2017-04-01

    Antiemetic guidelines recommend co-administration of targeted prophylactic medications inhibiting molecular pathways involved in emesis. NEPA is a fixed oral combination of a new NK 1 receptor antagonist (RA), netupitant (NETU 300 mg), and palonosetron (PALO 0.50 mg), a pharmacologically distinct 5-HT 3 RA. NEPA showed superior prevention of chemotherapy-induced nausea and vomiting (CINV) compared with oral PALO in a single chemotherapy cycle; maintenance of efficacy/safety over continuing cycles is the objective of this study. This study is a multinational, double-blind study comparing a single oral dose of NEPA vs oral PALO in chemotherapy-naïve patients receiving anthracycline/cyclophosphamide-based chemotherapy along with dexamethasone 12 mg (NEPA) or 20 mg (PALO) on day 1. The primary efficacy endpoint was delayed (25-120 h) complete response (CR: no emesis, no rescue medication) in cycle 1. Sustained efficacy was evaluated during the multicycle extension by calculating the proportion of patients with overall (0-120 h) CR in cycles 2-4 and by assessing the probability of sustained CR over multiple cycles. Of 1455 patients randomized, 1286 (88 %) participated in the multiple-cycle extension for a total of 5969 cycles; 76 % completed ≥4 cycles. The proportion of patients with an overall CR was significantly greater for NEPA than oral PALO for cycles 1-4 (74.3 vs 66.6 %, 80.3 vs 66.7 %, 83.8 vs 70.3 %, and 83.8 vs 74.6 %, respectively; p ≤ 0.001 each cycle). The cumulative percentage of patients with a sustained CR over all 4 cycles was also greater for NEPA (p < 0.0001). NEPA was well tolerated over cycles. NEPA, a convenient, guideline-consistent, fixed antiemetic combination is effective and safe over multiple cycles of chemotherapy.

  11. Lifecycle comparison of selected Li-ion battery chemistries under grid and electric vehicle duty cycle combinations

    Science.gov (United States)

    Crawford, Alasdair J.; Huang, Qian; Kintner-Meyer, Michael C. W.; Zhang, Ji-Guang; Reed, David M.; Sprenkle, Vincent L.; Viswanathan, Vilayanur V.; Choi, Daiwon

    2018-03-01

    Li-ion batteries are expected to play a vital role in stabilizing the electrical grid as solar and wind generation capacity becomes increasingly integrated into the electric infrastructure. This article describes how two different commercial Li-ion batteries based on LiNi0.8Co0.15Al0.05O2 (NCA) and LiFePO4 (LFP) chemistries were tested under grid duty cycles recently developed for two specific grid services: (1) frequency regulation (FR) and (2) peak shaving (PS) with and without being subjected to electric vehicle (EV) drive cycles. The lifecycle comparison derived from the capacity, round-trip efficiency (RTE), resistance, charge/discharge energy, and total used energy of the two battery chemistries are discussed. The LFP chemistry shows better stability for the energy-intensive PS service, while the NCA chemistry is more conducive to the FR service under the operating regimes investigated. The results can be used as a guideline for selection, deployment, operation, and cost analyses of Li-ion batteries used for different applications.

  12. Combined use of stable isotopes and hydrologic modeling to better understand nutrient sources and cycling in highly altered systems (Invited)

    Science.gov (United States)

    Young, M. B.; Kendall, C.; Guerin, M.; Stringfellow, W. T.; Silva, S. R.; Harter, T.; Parker, A.

    2013-12-01

    The Sacramento and San Joaquin Rivers provide the majority of freshwater for the San Francisco Bay Delta. Both rivers are important sources of drinking and irrigation water for California, and play critical roles in the health of California fisheries. Understanding the factors controlling water quality and primary productivity in these rivers and the Delta is essential for making sound economic and environmental water management decisions. However, these highly altered surface water systems present many challenges for water quality monitoring studies due to factors such as multiple potential nutrient and contaminant inputs, dynamic source water inputs, and changing flow regimes controlled by both natural and engineered conditions. The watersheds for both rivers contain areas of intensive agriculture along with many other land uses, and the Sacramento River receives significant amounts of treated wastewater from the large population around the City of Sacramento. We have used a multi-isotope approach combined with mass balance and hydrodynamic modeling in order to better understand the dominant nutrient sources for each of these rivers, and to track nutrient sources and cycling within the complex Delta region around the confluence of the rivers. High nitrate concentrations within the San Joaquin River fuel summer algal blooms, contributing to low dissolved oxygen conditions. High δ15N-NO3 values combined with the high nitrate concentrations suggest that animal manure is a significant source of nitrate to the San Joaquin River. In contrast, the Sacramento River has lower nitrate concentrations but elevated ammonium concentrations from wastewater discharge. Downstream nitrification of the ammonium can be clearly traced using δ15N-NH4. Flow conditions for these rivers and the Delta have strong seasonal and inter-annual variations, resulting in significant changes in nutrient delivery and cycling. Isotopic measurements and estimates of source water contributions

  13. Combining Maize Base Germplasm for Cold Tolerance Breeding

    OpenAIRE

    Rodríguez Graña, Víctor Manuel; Butrón Gómez, Ana María; Sandoya Miranda, Germán; Ordás Pérez, Amando; Revilla Temiño, Pedro

    2007-01-01

    Early planting can contribute to increased grain yield of maize (Zea mays L.), but it requires cold tolerance. A limited number of cold-tolerant maize genotypes have been reported. The objectives of this study were to test a new strategy to improve cold tolerance in maize searching for broad x narrow genetic combinations that may be useful as base populations for breeding programs, to compare genotype performance under cold-controlled and field conditions, and to establish the major genetic e...

  14. Probability Based Ship Design; Loads and Load Combinations

    Science.gov (United States)

    1993-11-01

    Ferry Borges, J. and Castenhata, M., "Structural Safety," Second Edition, Laboratario Nacional de Engenharia Civil , Lisbon, 1972. 3.18. Wen, Y.K...probability-based fatigue design, Thayamballi on fatigue load assessments, Munse on fatigue criteria, Wen on civil engineering load combinations, Mansour on...1.17. Ferry Borges, J. and Castenhata, M., "Structural Safety," Laboratoria Nacional de Engenhera Civil , Lisbon, 1971. 1.18. Engle, A. Private

  15. Solar Hydrogen Production via a Samarium Oxide-Based Thermochemical Water Splitting Cycle

    Directory of Open Access Journals (Sweden)

    Rahul Bhosale

    2016-04-01

    Full Text Available The computational thermodynamic analysis of a samarium oxide-based two-step solar thermochemical water splitting cycle is reported. The analysis is performed using HSC chemistry software and databases. The first (solar-based step drives the thermal reduction of Sm2O3 into Sm and O2. The second (non-solar step corresponds to the production of H2 via a water splitting reaction and the oxidation of Sm to Sm2O3. The equilibrium thermodynamic compositions related to the thermal reduction and water splitting steps are determined. The effect of oxygen partial pressure in the inert flushing gas on the thermal reduction temperature (TH is examined. An analysis based on the second law of thermodynamics is performed to determine the cycle efficiency (ηcycle and solar-to-fuel energy conversion efficiency (ηsolar−to−fuel attainable with and without heat recuperation. The results indicate that ηcycle and ηsolar−to−fuel both increase with decreasing TH, due to the reduction in oxygen partial pressure in the inert flushing gas. Furthermore, the recuperation of heat for the operation of the cycle significantly improves the solar reactor efficiency. For instance, in the case where TH = 2280 K, ηcycle = 24.4% and ηsolar−to−fuel = 29.5% (without heat recuperation, while ηcycle = 31.3% and ηsolar−to−fuel = 37.8% (with 40% heat recuperation.

  16. Systems Analysis of an Advanced Nuclear Fuel Cycle Based on a Modified UREX+3c Process

    Energy Technology Data Exchange (ETDEWEB)

    E. R. Johnson; R. E. Best

    2009-12-28

    The research described in this report was performed under a grant from the U.S. Department of Energy (DOE) to describe and compare the merits of two advanced alternative nuclear fuel cycles -- named by this study as the “UREX+3c fuel cycle” and the “Alternative Fuel Cycle” (AFC). Both fuel cycles were assumed to support 100 1,000 MWe light water reactor (LWR) nuclear power plants operating over the period 2020 through 2100, and the fast reactors (FRs) necessary to burn the plutonium and minor actinides generated by the LWRs. Reprocessing in both fuel cycles is assumed to be based on the UREX+3c process reported in earlier work by the DOE. Conceptually, the UREX+3c process provides nearly complete separation of the various components of spent nuclear fuel in order to enable recycle of reusable nuclear materials, and the storage, conversion, transmutation and/or disposal of other recovered components. Output of the process contains substantially all of the plutonium, which is recovered as a 5:1 uranium/plutonium mixture, in order to discourage plutonium diversion. Mixed oxide (MOX) fuel for recycle in LWRs is made using this 5:1 U/Pu mixture plus appropriate makeup uranium. A second process output contains all of the recovered uranium except the uranium in the 5:1 U/Pu mixture. The several other process outputs are various waste streams, including a stream of minor actinides that are stored until they are consumed in future FRs. For this study, the UREX+3c fuel cycle is assumed to recycle only the 5:1 U/Pu mixture to be used in LWR MOX fuel and to use depleted uranium (tails) for the makeup uranium. This fuel cycle is assumed not to use the recovered uranium output stream but to discard it instead. On the other hand, the AFC is assumed to recycle both the 5:1 U/Pu mixture and all of the recovered uranium. In this case, the recovered uranium is reenriched with the level of enrichment being determined by the amount of recovered plutonium and the combined amount

  17. Estimating the minimum delay optimal cycle length based on a time-dependent delay formula

    Directory of Open Access Journals (Sweden)

    Ahmed Y. Zakariya

    2016-09-01

    Full Text Available For fixed time traffic signal control, the well-known Webster’s formula is widely used to estimate the minimum delay optimal cycle length. However, this formula overestimates the cycle length for high degrees of saturation. In this paper, we propose two regression formulas for estimating the minimum delay optimal cycle length based on a time-dependent delay formula as used in the Canadian Capacity Guide and the Highway Capacity Manual (HCM. For this purpose, we develop a search algorithm to determine the minimum delay optimal cycle length required for the regression analysis. Numerical results show that the proposed formulas give a better estimation for the optimal cycle length at high intersection flow ratios compared to Webster’s formula.

  18. Synergy Maps: exploring compound combinations using network-based visualization.

    Science.gov (United States)

    Lewis, Richard; Guha, Rajarshi; Korcsmaros, Tamás; Bender, Andreas

    2015-01-01

    The phenomenon of super-additivity of biological response to compounds applied jointly, termed synergy, has the potential to provide many therapeutic benefits. Therefore, high throughput screening of compound combinations has recently received a great deal of attention. Large compound libraries and the feasibility of all-pairs screening can easily generate large, information-rich datasets. Previously, these datasets have been visualized using either a heat-map or a network approach-however these visualizations only partially represent the information encoded in the dataset. A new visualization technique for pairwise combination screening data, termed "Synergy Maps", is presented. In a Synergy Map, information about the synergistic interactions of compounds is integrated with information about their properties (chemical structure, physicochemical properties, bioactivity profiles) to produce a single visualization. As a result the relationships between compound and combination properties may be investigated simultaneously, and thus may afford insight into the synergy observed in the screen. An interactive web app implementation, available at http://richlewis42.github.io/synergy-maps, has been developed for public use, which may find use in navigating and filtering larger scale combination datasets. This tool is applied to a recent all-pairs dataset of anti-malarials, tested against Plasmodium falciparum, and a preliminary analysis is given as an example, illustrating the disproportionate synergism of histone deacetylase inhibitors previously described in literature, as well as suggesting new hypotheses for future investigation. Synergy Maps improve the state of the art in compound combination visualization, by simultaneously representing individual compound properties and their interactions. The web-based tool allows straightforward exploration of combination data, and easier identification of correlations between compound properties and interactions.

  19. Modeling Heavy/Medium-Duty Fuel Consumption Based on Drive Cycle Properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lijuan; Duran, Adam; Gonder, Jeffrey; Kelly, Kenneth

    2015-10-13

    This paper presents multiple methods for predicting heavy/medium-duty vehicle fuel consumption based on driving cycle information. A polynomial model, a black box artificial neural net model, a polynomial neural network model, and a multivariate adaptive regression splines (MARS) model were developed and verified using data collected from chassis testing performed on a parcel delivery diesel truck operating over the Heavy Heavy-Duty Diesel Truck (HHDDT), City Suburban Heavy Vehicle Cycle (CSHVC), New York Composite Cycle (NYCC), and hydraulic hybrid vehicle (HHV) drive cycles. Each model was trained using one of four drive cycles as a training cycle and the other three as testing cycles. By comparing the training and testing results, a representative training cycle was chosen and used to further tune each method. HHDDT as the training cycle gave the best predictive results, because HHDDT contains a variety of drive characteristics, such as high speed, acceleration, idling, and deceleration. Among the four model approaches, MARS gave the best predictive performance, with an average absolute percent error of -1.84% over the four chassis dynamometer drive cycles. To further evaluate the accuracy of the predictive models, the approaches were first applied to real-world data. MARS outperformed the other three approaches, providing an average absolute percent error of -2.2% of four real-world road segments. The MARS model performance was then compared to HHDDT, CSHVC, NYCC, and HHV drive cycles with the performance from Future Automotive System Technology Simulator (FASTSim). The results indicated that the MARS method achieved a comparative predictive performance with FASTSim.

  20. Life cycle impact assessment of bio-based plastics from sugarcane ethanol

    NARCIS (Netherlands)

    Tsiropoulos, I.; Faaij, A. P C; Lundquist, L.; Schenker, U.; Briois, J. F.; Patel, M. K.

    2015-01-01

    The increasing production of bio-based plastics calls for thorough environmental assessments. Using life cycle assessment, this study compares European supply of fully bio-based high-density polyethylene and partially bio-based polyethylene terephthalate from Brazilian and Indian sugarcane ethanol

  1. A study of combined evaluation of suppliers based on correlation

    Directory of Open Access Journals (Sweden)

    Heting Qiu

    2013-03-01

    Full Text Available Purpose: The Selection of logistics service providers is an important issue in supply chain management. But different evaluation methods may lead to different results, which could cause inconsistent conclusions. This paper makes use of a new perspective to combine with a variety of methods to eliminate the deviation of different single evaluation methods. Design/methodology/approach: This paper expounds the application of the combined evaluation method based on correlation. Entropy method, factor analysis, grey colligation evaluation and AHP have been used for research. Findings: According to the evaluate result, the ranking of suppliers obtained by each method have obvious differences. The result shows that combined evaluation method can eliminate the deviation of different single evaluation methods. Originality/value: The combined evaluation method makes up for the defects of single evaluation methods and obtains a result that is more stable and creditable with smaller deviation. This study can provide the enterprise leaders with more scientific method to select their cooperative companies. 

  2. Life Cycle Assessment of Paper Based Printed Circuits

    OpenAIRE

    Wan, Qiansu

    2017-01-01

    Printed circuit boards have been massively manufactured and wildly used in all kinds of electronic devices during people’s daily life for more than thirty years since the last century. As a highly integrated device mainly consists of silicon base, an etched copper layer and other soldered components, massive production of printed circuit boards are considered to be environmentally unfriendly due to the wet chemical manufacturing mode and lack of recycling ability. On the other hand, the newly...

  3. The extension of Ubungo power plant in Dar es Salaam, Tanzania, to a combined cycle - A prestudy

    Energy Technology Data Exchange (ETDEWEB)

    Grinneland, L.; Oehrstroem, K.

    1996-05-01

    The report deals with the consequences concerning a future extension of Ubungo Power Plant. Today the power plant consists of four gas turbines, two of model General Electric LM6000 and two of model ABB Stal GT10 of which the latter were the ones focused on. In the report four different applications are presented; Simple two pressure system, Two pressure system with reheat, Two pressure system with heat exchange between feedwater and condensate, and single pressure system with an additional evaporating loop. The calculations are divided into three sections; thermodynamic calculations, calculations of the heat exchanger surface areas, and economic calculations. From the thermodynamic calculations the applications with the highest thermal efficiency was selected. The power output increased with about 55% and the thermal efficiency of the complete combined cycle is 48.2%. This is, of course, a theoretical value calculated without consideration to a number of losses that will decrease both the power output and the thermal efficiency. At part load (50% load assumed, i.e. one gas turbine is operating) the thermal efficiency is 46.7%. The economic calculations indicated that the extension is highly worthwhile in an economic point of view; both cases studied have a payback time of less than six years for full load operation, provided that the charging system which is to be imposed by the World Bank has come into force. 18 refs, 33 figs

  4. Coordinated control of a combined cycle thermoelectric central; Control coordinado de una central termoelectrica de ciclo combinado

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Parra, Marino; Castelo Cuevas, Luis [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1998-03-01

    In this paper the coordinated control (CC) of the Distributed Control System (Sistema de Control Distribuido) (SICODI) of the Combined Cycle Central of Gomez Palacio, Durango, is presented. The description of the control scheme and its realization in software is made. From the scheme the operation strategies and automation, supervision and control are described in detail. The software components of the programming are described, the program structure and control data and its implementation in working stations VAX 3100 under the operating system VMS (Virtual Memory System), are described. [Espanol] En este articulo se presenta el control coordinado (CC) del Sistema de Control Distribuido (Sicodi) de la central de ciclo combinado Gomez Palacio, Durango. Se describe el esquema de control y su realizacion en software. Del esquema se detallan las estrategias de operacion y automatizacion, supervision y control. Del software se describen los componentes de la programacion, la estructura de programas y datos del control y su implementacion en estaciones de trabajo VAX 3100 bajo el sistema operativo VMS (Virtual Memory System).

  5. Multi-objective optimization of an advanced combined cycle power plant including CO{sub 2} separation options

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongtao; Marechal, Francois; Burer, Meinrad; Favrat, Daniel [Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland). Laboratory for Industrial Energy Systems

    2006-12-15

    This paper illustrates a methodology developed to facilitate the analysis of complex systems characterized by a large number of technical, economical and environmental parameters. Thermo-economic modeling of a natural gas combined cycle including CO{sub 2} separation options has been coupled within a multi-objective evolutionary algorithm to characterize the economic and environmental performances of such complex systems within various contexts. The method has been applied to a case of power generation in Germany. The optimum options for system integration under different boundary conditions are revealed by the Pareto Optimal Frontiers. Results show the influence of the configuration and technical parameters on the electrical efficiencies of the Pareto optimal plants and their sub-systems. The results provide information on the relationship between power generation cost and CO{sub 2} emissions, and allow sensitivity analyses of important economical parameters like natural gas and electricity prices. Such a tool is of interest for power generation technology suppliers, for utility owners or for project investors, and for policy makers in the context of CO{sub 2} mitigation schemes including emission trading. (author)

  6. Report of study group 7.2: comparison of medium or large scale CHP and combined cycles, in various countries

    Energy Technology Data Exchange (ETDEWEB)

    Roncato, J.P. [Finergaz (France); Macchi, E. [Politecnico di Milano, Milan (Italy)

    2000-07-01

    At the turn of the third millennium, important changes are occurring in terms of energy policy and deregulation of the energy market, in numerous countries. It is clear that cogeneration has undergone an impressive development in a large number of countries, over the last five years. But it is also clear that gas fired electricity production will have to face a much more uncertain situation in the coming years with less predictability concerning both energy prices and costs of access to the grids in a de-regulated context, and more generally regarding economic environment of the projects. The aim of the present report is to show that even with different situations, concerning energy prices, conditions of access to the grid and incentives, there is a logical link between the profitability and the development rate of cogeneration or combined cycles in different countries. Detailed data have therefore been collected from a selection of countries, in order to compare on a consistent basis the profitability of several typical projects. From these data, the study group has then been able to compute the pay-back of these projects for each country, and to perform a sensitivity analysis to different parameters. Data were collected from Japan and 10 European countries represented in the study group. In spite of several contacts, it was unfortunately not possible to collect consistent data from a larger number of other countries, nevertheless the study group believes that the results obtained are representative of a significant range of situations. (authors)

  7. Life cycle energy use and GHG emission assessment of coal-based SNG and power cogeneration technology in China

    International Nuclear Information System (INIS)

    Li, Sheng; Gao, Lin; Jin, Hongguang

    2016-01-01

    Highlights: • Life cycle energy use and GHG emissions are assessed for SNG and power cogeneration. • A model based on a Chinese domestic database is developed for evaluation. • Cogeneration shows lower GHG emissions than coal-power pathway. • Cogeneration has lower life cycle energy use than supercritical coal-power pathway. • Cogeneration is a good option to implement China’s clean coal technologies. - Abstract: Life cycle energy use and GHG emissions are assessed for coal-based synthetic natural gas (SNG) and power cogeneration/polygenereation (PG) technology and its competitive alternatives. Four main SNG applications are considered, including electricity generation, steam production, SNG vehicle and battery electric vehicle (BEV). Analyses show that if SNG is produced from a single product plant, the lower limits of its life cycle energy use and GHG emissions can be comparable to the average levels of coal-power and coal-BEV pathways, but are still higher than supercritical and ultra supercritical (USC) coal-power and coal-BEV pathways. If SNG is coproduced from a PG plant, when it is used for power generation, steam production, and driving BEV car, the life cycle energy uses for PG based pathways are typically lower than supercritical coal-power pathways, but are still 1.6–2.4% higher than USC coal-power pathways, and the average life cycle GHG emissions are lower than those of all coal-power pathways including USC units. If SNG is used to drive vehicle car, the life cycle energy use and GHG emissions of PG-SNGV-power pathway are both much higher than all combined coal-BEV and coal-power pathways, due to much higher energy consumption in a SNG driven car than in a BEV car. The coal-based SNG and power cogeneration technology shows comparable or better energy and environmental performances when compared to other coal-based alternatives, and is a good option to implement China’s clean coal technologies.

  8. Performance Analysis of the Vehicle Diesel Engine-ORC Combined System Based on a Screw Expander

    Directory of Open Access Journals (Sweden)

    Kai Yang

    2014-05-01

    Full Text Available To achieve energy saving and emission reduction for vehicle diesel engines, the organic Rankine cycle (ORC was employed to recover waste heat from vehicle diesel engines, R245fa was used as ORC working fluid, and the resulting vehicle diesel engine-ORC combined system was presented. The variation law of engine exhaust energy rate under various operating conditions was obtained, and the running performances of the screw expander were introduced. Based on thermodynamic models and theoretical calculations, the running performance of the vehicle diesel engine-ORC combined system was analyzed under various engine operating condition scenarios. Four evaluation indexes were defined: engine thermal efficiency increasing ratio (ETEIR, waste heat recovery efficiency (WHRE, brake specific fuel consumption (BSFC of the combined system, and improvement ratio of BSFC (IRBSFC. Results showed that when the diesel engine speed is 2200 r/min and diesel engine torque is 1200 N·m, the power output of the combined system reaches its maximum of approximately 308.6 kW, which is 28.6 kW higher than that of the diesel engine. ETEIR, WHRE, and IRBSFC all reach their maxima at 10.25%, 9.90%, and 9.30%, respectively. Compared with that of the diesel engine, the BSFC of the combined system is obviously improved under various engine operating conditions.

  9. Energy-analysis of the total nuclear energy cycle based on light water reactors

    International Nuclear Information System (INIS)

    Kistemaker, J.

    1975-01-01

    The energy economy of the total nuclear energy cycle is investigated. Attention is paid to the importance of fossil fuel saving by using nuclear energy. The energy analysis is based on the construction and operation of power plants with an electric output of 1000MWe. Light water moderated reactors with a 2.7 - 3.2% enriched uranium core are considered. Additionally, the whole fuel cycle including ore winning and refining, enrichment and fuel element manufacturing and reprocessing has been taken into account. Neither radioactive waste storage problems nor safety problems related to the nuclear energy cycle and safeguarding have been dealt with, as exhaustive treatments can be found elswhere

  10. The colour preference control based on two-colour combinations

    Science.gov (United States)

    Hong, Ji Young; Kwak, Youngshin; Park, Du-Sik; Kim, Chang Yeong

    2008-02-01

    This paper proposes a framework of colour preference control to satisfy the consumer's colour related emotion. A colour harmony algorithm based on two-colour combinations is developed for displaying the images with several complementary colour pairs as the relationship of two-colour combination. The colours of pixels belonging to complementary colour areas in HSV colour space are shifted toward the target hue colours and there is no colour change for the other pixels. According to the developed technique, dynamic emotions by the proposed hue conversion can be improved and the controlled output image shows improved colour emotions in the preference of the human viewer. The psychophysical experiments are conducted to investigate the optimal model parameters to produce the most pleasant image to the users in the respect of colour emotions.

  11. Life Cycle Assessment on Cement Treated Recycling Base (CTRB Construction

    Directory of Open Access Journals (Sweden)

    Sudarno Sudarno

    2014-08-01

    Full Text Available LCA is one of the few environmental management techniques that are used to perform a risk assessment, environmental performance evaluation, environmental auditing, and environmental impact assessment and must be applied to the construction CTRB. The purpose of this study was to determine the amount of energy consumption is used and determine the amount of emissions (CO2 in the implementation of the Foundation Layer Top (base course with the former asphalt pavement aggregate blended cement / Recycling Cement Treated Base (CTRB. This study uses: (i Compilation and data inventory of relevant inputs and outputs of a product system; (ii Evaluating the potential environmental impacts associated with the data input and output; (iii Interpret the results of the inventory analysis and impact assessment in relation to the research objectives. The results showed that Energy consumption in the implementation of recycling pavement (CTRB is 225.46 MJ / km of roads and the resulting GHG emissions 17,43Ton CO2 / km of roads. Previous researchers to calculate the energy consumption of road works on the implementation of conventional (hotmix is 383.46 MJ / km of roads and the resulting GHG emissions 28.24 Ton CO2 / km of roads. If the calculated difference between a job and Hotmix CTRB and then a comparison is made CTRB energy consumption is 158 MJ / km of road, this happens 70.07% savings and GHG emissions resulting difference is 10.81 tons of CO2 / km of road, resulting in a decrease in 62,02%.

  12. Seasonality in swimming and cycling: Exploring a limitation of accelerometer based studies

    OpenAIRE

    Harrison, Flo; atkin, Andrew James; van sluijs, Esther Maria; Jones, A

    2017-01-01

    Accelerometer-based studies of children's physical activity have reported seasonal patterns in activity levels. However, the inability of many accelerometers to detect activity while the wearer is swimming or cycling may introduce a bias to the estimation of seasonality if participation in these activities are themselves seasonally patterned. We explore seasonal patterns in children's swimming and cycling among a sample of 7–8 year olds ($N$ = 591) participating in the Millennium Cohort Study...

  13. Evaluation of green building rating tools based on existing green building achievement in Indonesia using Life Cycle Assessment Method

    Science.gov (United States)

    Basten, Van; Latief, Yusuf; Berawi, Mohammed Ali; Budiman, Rachmat; Riswanto

    2017-03-01

    Total completed building construction value in Indonesia increased 116% during 2009 to 2011. That's followed by increasing 11% energy consumption in Indonesia in the last three years with 70% energy met to the electricity needs of commercial building. In addition, a few application of green building concept in Indonesia made the greenhouse gas emissions or CO2 amount increased by 25%. Construction, operation, and maintain of building cost consider relatively high. The evaluation in this research is used to improve the building performance with some of green concept alternatives. The research methodology is conducted by combination of qualitative and quantitative approaches through interview and case study. Assessing the successful of optimization functions in the existing green building is based on the operational and maintenance phase with the Life Cycle Assessment (LCA) Method. The result of optimization that is the largest efficiency and effective of building life cycle.

  14. A phase plane graph based model of the ovulatory cycle lacking the "positive feedback" phenomenon

    Directory of Open Access Journals (Sweden)

    Kurbel Sven

    2012-08-01

    Full Text Available Abstract When hormones during the ovulatory cycle are shown in phase plane graphs, reported FSH and estrogen values form a specific pattern that resembles the leaning “&" symbol, while LH and progesterone (Pg values form a "boomerang" shape. Graphs in this paper were made using data reported by Stricker et al. [Clin Chem Lab Med 2006;44:883–887]. These patterns were used to construct a simplistic model of the ovulatory cycle without the conventional "positive feedback" phenomenon. The model is based on few well-established relations: hypothalamic GnRH secretion is increased under estrogen exposure during two weeks that start before the ovulatory surge and lasts till lutheolysis. the pituitary GnRH receptors are so prone to downregulation through ligand binding that this must be important for their function. in several estrogen target tissue progesterone receptor (PgR expression depends on previous estrogen binding to functional estrogen receptors (ER, while Pg binding to the expressed PgRs reduces both ER and PgR expression. Some key features of the presented model are here listed: High GnRH secretion induced by the recovered estrogen exposure starts in the late follicular phase and lasts till lutheolysis. The LH and FSH surges start due to combination of accumulated pituitary GnRH receptors and increased GnRH secretion. The surges quickly end due to partial downregulation of the pituitary GnRH receptors (64% reduction of the follicular phase pituitary GnRH receptors is needed to explain the reported LH drop after the surge. A strong increase in the lutheal Pg blood level, despite modest decline in LH levels, is explained as delayed expression of pituitary PgRs. Postponed pituitary PgRs expression enforces a negative feedback loop between Pg levels and LH secretions not before the mid lutheal phase. Lutheolysis is explained as a consequence of Pg binding to hypothalamic and pituitary PgRs that reduces local ER expression. When hypothalamic

  15. Combining Unsteady Blade Pressure Measurements and a Free-Wake Vortex Model to Investigate the Cycle-to-Cycle Variations in Wind Turbine Aerodynamic Blade Loads in Yaw

    Directory of Open Access Journals (Sweden)

    Moutaz Elgammi

    2016-06-01

    Full Text Available Prediction of the unsteady aerodynamic flow phenomenon on wind turbines is challenging and still subject to considerable uncertainty. Under yawed rotor conditions, the wind turbine blades are subjected to unsteady flow conditions as a result of the blade advancing and retreating effect and the development of a skewed vortical wake created downstream of the rotor plane. Blade surface pressure measurements conducted on the NREL Phase VI rotor in yawed conditions have shown that dynamic stall causes the wind turbine blades to experience significant cycle-to-cycle variations in aerodynamic loading. These effects were observed even though the rotor was subjected to a fixed speed and a uniform and steady wind flow. This phenomenon is not normally predicted by existing dynamic stall models integrated in wind turbine design codes. This paper couples blade pressure measurements from the NREL Phase VI rotor to a free-wake vortex model to derive the angle of attack time series at the different blade sections over multiple rotor rotations and three different yaw angles. Through the adopted approach it was possible to investigate how the rotor self-induced aerodynamic load fluctuations influence the unsteady variations in the blade angles of attack and induced velocities. The hysteresis loops for the normal and tangential load coefficients plotted against the angle of attack were plotted over multiple rotor revolutions. Although cycle-to-cycle variations in the angles of attack at the different blade radial locations and azimuth positions are found to be relatively small, the corresponding variations in the normal and tangential load coefficients may be significant. Following a statistical analysis, it was concluded that the load coefficients follow a normal distribution at the majority of blade azimuth angles and radial locations. The results of this study provide further insight on how existing engineering models for dynamic stall may be improved through

  16. Market-Based and System-Wide Fuel Cycle Optimization

    International Nuclear Information System (INIS)

    Wilson, Paul

    2016-01-01

    The Dynamic Resource Exchange (DRE) gives agency to consumer facilities to determine the preference of any particular trade that is offered by suppliers to satisfy its requests. This provides a natural balance of power in the relationship between consumers and suppliers. However, in situations in which suppliers have flexibility surrounding the way that they respond to individual requests, they have no mechanism to assess how different bids will be received by the consumer. Theoretically, a supplier can offer multiple bids to respond to a given request in an attempt to cover their bases, but this introduces more arcs into the underlying network flow problem, increasing the cost to solve the problem. In the extreme, when a supplier can continuously vary the characteristics of the bid, this can represent a large number of additional arcs and have real performance consequences. To remedy this inefficiency in the implementation of the market-level optimization, the definition of a request has been extended to include a function that can be used by the supplier to query the preference that would be assigned by a consumer for a potential bid. The supplier is then free to implement arbitrarily complex algorithms to revise/optimize its bid based on responses to this function. A supplier can chose to not invoke the function at all, mimicking the original DRE behavior, can use it to select among a small set of discrete choices, or can implement an internal algorithm to seek an optimum bid on a continuous parameter space. This capability was demonstrated with a storage facility that preferred material with a specific decay heat that was as close as possible to the maximum allowable decay heat, while requiring the specific decay heat to fall between a minimum and maximum level. This archetype was used to fill multiple storage roles in a simulation that also included a standard recipe reactor: wet storage with no maximum allowable specific decay heat, dry storage with a modest

  17. Life-cycle analysis of bio-based aviation fuels.

    Science.gov (United States)

    Han, Jeongwoo; Elgowainy, Amgad; Cai, Hao; Wang, Michael Q

    2013-12-01

    Well-to-wake (WTWa) analysis of bio-based aviation fuels, including hydroprocessed renewable jet (HRJ) from various oil seeds, Fischer-Tropsch jet (FTJ) from corn-stover and co-feeding of coal and corn-stover, and pyrolysis jet from corn stover, is conducted and compared with petroleum jet. WTWa GHG emission reductions relative to petroleum jet can be 41-63% for HRJ, 68-76% for pyrolysis jet and 89% for FTJ from corn stover. The HRJ production stage dominates WTWa GHG emissions from HRJ pathways. The differences in GHG emissions from HRJ production stage among considered feedstocks are much smaller than those from fertilizer use and N2O emissions related to feedstock collection stage. Sensitivity analyses on FTJ production from coal and corn-stover are also conducted, showing the importance of biomass share in the feedstock, carbon capture and sequestration options, and overall efficiency. For both HRJ and FTJ, co-product handling methods have significant impacts on WTWa results. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Combined cycling and calendar capacity fade modeling of a Nickel-Manganese-Cobalt Oxide Cell with real-life profile validation

    DEFF Research Database (Denmark)

    de Hoog, Joris; Timmermans, Jean-Marc; Stroe, Daniel-Ioan

    2017-01-01

    This paper presents the development of a semi-empirical combined lifetime model for a Nickel Manganese Cobalt Oxide (NMC) cathode and a graphite anode based cell, considered as one of the most promising candidates for the automotive industry. The development of this model was based on a thorough...... understanding of the degradation behavior of a 20-A h NMC cell, based on the analysis of the results of an extensive test-matrix using 146 cells. This test-matrix was designed around four impact factors: temperature (25–45 °C), Depth-of-Discharge (100–20% DoD), middle State-of-Charge (80–20% Mid......-SoC) and current rates (C/3 to 2C). Gathering sufficient data for a mathematical model requires a huge time-investment, and the measurements gathered over the course of 2.5 years offer a unique insight in the aging behavior of the NMC cells used in this study. Experimental results for cycling aging indicated...

  19. Thermodynamic System Studies for a Natural Gas Combined Cycle (NGCC) Plant with CO2 Capture and Hydrogen Storage with Metal Hydrides

    OpenAIRE

    Thallam Thattai, A.; Wittebrood, B.J.; Woudstra, T.; Geerlings, J.J.C.; Aravind, P.V.

    2014-01-01

    Flexibility in natural gas combined cycle power plants (NGCC) with pre-combustion CO2 capture could be introduced with co-production of hydrogen and subsequent hydrogen storage with metal hydrides (MH). The current work presents a thermodynamic analysis and comparison between steady state ASPEN Plus models of a reference case NGCC plant with no capture and H2 storage, an NGCC plant with pre-combustion capture using gas heated - auto thermal reformer (GHR-ATR) combined with a sorption enhanced...

  20. The effect of cycling deflection on the injection-molded thermoplastic denture base resins.

    Science.gov (United States)

    Hamanaka, Ippei; Iwamoto, Misa; Lassila, Lippo Vj; Vallittu, Pekka K; Shimizu, Hiroshi; Takahashi, Yutaka

    2016-01-01

    The aim of this study was to evaluate the effect of cycling deflection on the flexural behavior of injection-molded thermoplastic resins. Six injection-molded thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethyl methacrylate) and, as a control, a conventional heat-polymerized denture based polymer of polymethyl methacrylate (PMMA) were used in this study. The cyclic constant magnitude (1.0 mm) of 5000 cycles was applied using a universal testing machine to demonstrate plasticization of the polymer. Loading was carried out in water at 23ºC with eight specimens per group (n = 8). Cycling load (N) and deformation (mm) were measured. Force required to deflect the specimens during the first loading cycle and final loading cycle was statistically significantly different (p 0.05). None of the materials fractured during the loading test. One polyamide based polymer (Valplast) displayed the highest deformation and PMMA based polymers (Acrytone and Acron) exhibited the second highest deformation among the denture base materials. It can be concluded that there were considerable differences in the flexural behavior of denture base polymers. This may contribute to the fatigue resistance of the materials.

  1. Market-Based and System-Wide Fuel Cycle Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Paul [Univ. of Wisconsin, Madison, WI (United States)

    2016-06-02

    The Dynamic Resource Exchange (DRE) gives agency to consumer facilities to determine the preference of any particular trade that is offered by suppliers to satisfy its requests. This provides a natural balance of power in the relationship between consumers and suppliers. However, in situations in which suppliers have flexibility surrounding the way that they respond to individual requests, they have no mechanism to assess how different bids will be received by the consumer. Theoretically, a supplier can offer multiple bids to respond to a given request in an attempt to “cover their bases”, but this introduces more arcs into the underlying network flow problem, increasing the cost to solve the problem. In the extreme, when a supplier can continuously vary the characteristics of the bid, this can represent a large number of additional arcs and have real performance consequences. To remedy this inefficiency in the implementation of the market-level optimization, the definition of a request has been extended to include a function that can be used by the supplier to query the preference that would be assigned by a consumer for a potential bid. The supplier is then free to implement arbitrarily complex algorithms to revise/optimize its bid based on responses to this function. A supplier can chose to not invoke the function at all, mimicking the original DRE behavior, can use it to select among a small set of discrete choices, or can implement an internal algorithm to seek an optimum bid on a continuous parameter space. This capability was demonstrated with a storage facility that preferred material with a specific decay heat that was as close as possible to the maximum allowable decay heat, while requiring the specific decay heat to fall between a minimum and maximum level. This archetype was used to fill multiple storage roles in a simulation that also included a standard recipe reactor: wet storage with no maximum allowable specific decay heat, dry storage with a

  2. Ignition of deuterium based fuel cycles in a high beta system

    International Nuclear Information System (INIS)

    Hirano, K.

    1987-01-01

    A steady state self-consistent plasma modeling applied to a system having close to unity, such as FRC or like, is found to be quite effective in solving the problems independently of any anomalous process and proves the existence of ignited state of deuterium based fuel cycles. The temperature ranges that the plasma falls into ignited state are obtained as a function of relative feeding rates of tritium and 3 He to deuterium's. We find pure DD cycle will not ignite so that 3 He or/and tritium must be added as catalyzer to achieve ignition. Standing on the points to construct a cleaner system yielding smaller amount of 14 MeV neutrons and to burn the fuel in steady state for long periods of time, we have confirmed superiority of the complex composed of the master reactor of 3 He-Cat.D cycle (catalyzed DD cycle reinjecting only fusion produced 3 He) and the satellite reactor of 3 He enriched D 3 He cycle. In case storage of tritium for 3 He by β - decay is turned out not to be allowed environmentally, we may utilize conventional catalyzed DD cycle although 14 MeV neutron yields will be increased by 35 % over the complex. It is demonstrated that advanced fuel cycle reactors can be very simple in constructions and compact in size such that the field strength and the plasma volume of the order of JT-60's may be enough for 1000 MW power plant. (author)

  3. Seasonality in swimming and cycling: Exploring a limitation of accelerometer based studies

    Directory of Open Access Journals (Sweden)

    Flo Harrison

    2017-09-01

    Full Text Available Accelerometer-based studies of children's physical activity have reported seasonal patterns in activity levels. However, the inability of many accelerometers to detect activity while the wearer is swimming or cycling may introduce a bias to the estimation of seasonality if participation in these activities are themselves seasonally patterned. We explore seasonal patterns in children's swimming and cycling among a sample of 7–8 year olds (N = 591 participating in the Millennium Cohort Study, UK. Participating children wore an accelerometer for one week on up to five occasions over the year and their parents completed a diary recording daily minutes spent swimming and cycling. Both swimming and cycling participation showed seasonal patterns, with 2.7 (SE 0.8 more minutes swimming and 5.7 (0.7 more minutes cycling performed in summer compared to winter. Adding swimming and cycling time to accelerometer-determined MVPA increased the summer-winter difference in MVPA from 16.6 (1.6 to 24.9 min. The seasonal trend in swimming and cycling appears to follow the same pattern as accelerometer-measured MVPA. Studies relying solely on accelerometers may therefore underestimate seasonal differences in children's activity.

  4. An Imaging Flow Cytometry-based approach to analyse the fission yeast cell cycle in fixed cells.

    Science.gov (United States)

    Patterson, James O; Swaffer, Matthew; Filby, Andrew

    2015-07-01

    Fission yeast (Schizosaccharomyces pombe) is an excellent model organism for studying eukaryotic cell division because many of the underlying principles and key regulators of cell cycle biology are conserved from yeast to humans. As such it can be employed as tool for understanding complex human diseases that arise from dis-regulation in cell cycle controls, including cancers. Conventional Flow Cytometry (CFC) is a high-throughput, multi-parameter, fluorescence-based single cell analysis technology. It is widely used for studying the mammalian cell cycle both in the context of the normal and disease states by measuring changes in DNA content during the transition through G1, S and G2/M using fluorescent DNA-binding dyes. Unfortunately analysis of the fission yeast cell cycle by CFC is not straightforward because, unlike mammalian cells, cytokinesis occurs after S-phase meaning that bi-nucleated G1 cells have the same DNA content as mono-nucleated G2 cells and cannot be distinguished using total integrated fluorescence (pulse area). It has been elegantly shown that the width of the DNA pulse can be used to distinguish G2 cells with a single 2C foci versus G1 cells with two 1C foci, however the accuracy of this measurement is dependent on the orientation of the cell as it traverses the laser beam. To this end we sought to improve the accuracy of the fission yeast cell cycle analysis and have developed an Imaging Flow Cytometry (IFC)-based method that is able to preserve the high throughput, objective analysis afforded by CFC in combination with the spatial and morphometric information provide by microscopy. We have been able to derive an analysis framework for subdividing the yeast cell cycle that is based on intensiometric and morphometric measurements and is thus robust against orientation-based miss-classification. In addition we can employ image-based metrics to define populations of septated/bi-nucleated cells and measure cellular dimensions. To our knowledge

  5. Early human-plant interactions based on palaeovegetation simulations of Africa over glacial-interglacial cycles

    Science.gov (United States)

    Cowling, S. A.; Cox, P. M.; Jones, C. D.; Maslin, M. A.; Spall, S. A.

    2003-04-01

    A greater understanding of African palaeovegetation environments over the Pleistocene (1.6 Mya) is important for evaluating potential catalysts underlying the anatomical, social and demographic changes observed in early human populations. We used a state-of-the-art fully-coupled earth system model (HADLEY-GCM3) to simulate typical glacial and interglacial environments likely encountered by late-Pleistocene humans. Our simulations indicate that tropical broadleaf forests of central Africa were not severely restricted by expanding grasslands during the last glacial maximum, although the carbon content of stem and density of leaf components were substantially reduced. We interpret a natural eastern migration corridor between southern Africa and the Rift Valley based on simulations of a no-analogue vegetation assemblage characterised by a unique combination of grass and low density forest. We postulate that early human populations in southern Africa were isolated from northern groups during warm interglacials, and that trans-African migration was facilitated during glacial cycles via a more openly forested eastern corridor.

  6. Selection of odour removal technologies in wastewater treatment plants: a guideline based on Life Cycle Assessment.

    Science.gov (United States)

    Alfonsín, Carolina; Lebrero, Raquel; Estrada, José M; Muñoz, Raúl; Kraakman, N J R Bart; Feijoo, Gumersindo; Moreira, M Teresa

    2015-02-01

    This paper aims at analysing the environmental benefits and impacts associated with the treatment of malodorous emissions from wastewater treatment plants (WWTPs). The life cycle assessment (LCA) methodology was applied to two biological treatments, namely biofilter (BF) and biotrickling filter (BTF), two physical/chemical alternatives, namely activated carbon tower (AC) and chemical scrubber (CS), and a hybrid combination of BTF + AC. The assessment provided consistent guidelines for technology selection, not only based on removal efficiencies, but also on the environmental impact associated with the treatment of emissions. The results showed that biological alternatives entailed the lowest impacts. On the contrary, the use of chemicals led to the highest impacts for CS. Energy use was the main contributor to the impact related to BF and BTF, whereas the production of glass fibre used as infrastructure material played an important role in BTF impact. Production of NaClO entailed the highest burdens among the chemicals used in CS, representing ∼ 90% of the impact associated to chemicals. The frequent replacement of packing material in AC was responsible for the highest environmental impacts, granular activated carbon (GAC) production and its final disposal representing more than 50% of the impact in most categories. Finally, the assessment of BTF + AC showed that the hybrid technology is less recommendable than BF and BTF, but friendlier to the environment than physical/chemical treatments. Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Improving the performances of gas turbines operated on natural gas in combined cycle power plants with application of mathematical models

    International Nuclear Information System (INIS)

    Dimkovski, Sasho

    2014-01-01

    The greater energy demand by today society sets a number of new challenges in the energy sector. The climate extremes impose new modes of operation of the power plants, with high flexibility in production. Combined cycle co generative power plants are the latest trend in the energy sector. Their high prevalence is due to the great efficiency and the good environmental characteristics. The main work horse in these cogeneration plants is the gas turbine, which power production and efficiency strongly depends on the external climate conditions. In warmer periods when there is increased demand for electricity, the power production from the gas turbines significantly declines. Because of the high electricity demand from the grid and reduced power production from the gas turbines at the same time, the need for application of appropriate technology for preserving the performances and power of the gas turbines arises. This master thesis explores different methods to improve the power in gas turbines by cooling the air on the compressor inlet, analyzing their applicability and effectiveness in order to choose the optimal method for power augmentation for the climatic conditions in the city Skopje. The master thesis gives detailed analysis of the weather in Skopje and the time frame in which the chosen method is applicable. At the end in the master thesis, the economic feasibility of the given method for power augmentation is clearly calculated, using a model of a power plant and calculating the resulting amount of gained energy, the amount of the initial investment, the cost for maintenance and operation of the equipment. By these calculations the period for initial return of investment is obtained. As an added benefit the positive environmental impacts of the applied technology for inlet air cooling is analyzed. (author)

  8. Single and Combined Effects of Beetroot Crystals and Sodium Bicarbonate on 4-km Cycling Time Trial Performance.

    Science.gov (United States)

    Callahan, Marcus J; Parr, Evelyn B; Hawley, John A; Burke, Louise M

    2017-06-01

    When ingested alone, beetroot juice and sodium bicarbonate are ergogenic for high-intensity exercise performance. This study sought to determine the independent and combined effects of these supplements. Eight endurance trained (VO 2 max 65 mL·kg·min -1 ) male cyclists completed four × 4-km time trials (TT) in a doubleblind Latin square design supplementing with beetroot crystals (BC) for 3 days (15 g·day -1 + 15 g 1 h before TT, containing 300 mg nitrate per 15 g), bicarbonate (Bi 0.3 g·kg -1 body mass [BM] in 5 doses every 15 min from 2.5 h before TT); BC+Bi or placebo (PLA). Subjects completed TTs on a Velotron cycle ergometer under standardized laboratory conditions. Plasma nitrite concentrations were significantly elevated only in the BC+Bi trial before the TT (1520 ± 786 nmol·L -1 ) compared with baseline (665 ± 535 nmol·L -1 , p = .02) and the Bi and PLA conditions (Bi: 593 ± 203 nmol·L -1 , p .05). Blood bicarbonate concentrations were increased in the BC+Bi and Bi trials before the TT (BC+Bi: 30.9 ± 2.8 mmol·L -1 ; Bi: 31.7 ± 1.1 mmol·L -1 ). There were no differences in mean power output (386-394 W) or the time taken to complete the TT (335.8-338.1 s) between any conditions. Under the conditions of this study, supplementation was not ergogenic for 4-km TT performance.

  9. Thermodynamic System Studies for a Natural Gas Combined Cycle (NGCC) Plant with CO2 Capture and Hydrogen Storage with Metal Hydrides

    NARCIS (Netherlands)

    Thallam Thattai, A.; Wittebrood, B.J.; Woudstra, T.; Geerlings, J.J.C.; Aravind, P.V.

    2014-01-01

    Flexibility in natural gas combined cycle power plants (NGCC) with pre-combustion CO2 capture could be introduced with co-production of hydrogen and subsequent hydrogen storage with metal hydrides (MH). The current work presents a thermodynamic analysis and comparison between steady state ASPEN Plus

  10. Techno-environmental assessment of the green biorefinery concept: Combining process simulation and life cycle assessment at an early design stage

    DEFF Research Database (Denmark)

    Corona, Andrea; Ambye-Jensen, Morten; Vega, Giovanna Croxatto

    2018-01-01

    The Green biorefinery (GBR) is a biorefinery concept that converts fresh biomass into value-added products. The present study combines a Process Flowsheet Simulation (PFS) and Life Cycle Assessment (LCA) to evaluate the technical and environmental performance of different GBR configurations...

  11. An SSVEP-based BCI using high duty-cycle visual flicker.

    Science.gov (United States)

    Lee, Po-Lei; Yeh, Chia-Lung; Cheng, John Yung-Sung; Yang, Chia-Yen; Lan, Gong-Yau

    2011-12-01

    Steady-state visual-evoked potential (SSVEP)-based brain-computer interfaces (BCIs) have generated significant interest due to their high information transfer rate (ITR). Due to the amplitude-frequency characteristic of the SSVEP, the flickering frequency of an SSVEP-based BCI is typically lower than 20  Hz to achieve a high SNR. However, a visual flicker with a flashing frequency below the critical flicker-fusion frequency often makes subjects feel flicker jerky and causes visual discomfort. This study presents a novel technique using high duty-cycle visual flicker to decrease user's visual discomfort. The proposed design uses LEDs flashing at 13.16  Hz, driven by flickering sequences consisting of repetitive stimulus cycles with a duration T (T = 76 ms). Each stimulus cycle included an ON state with a duration T(ON) and an OFF state with a duration T(OFF) (T = T(ON) + T(OFF)), and the duty cycle, defined as T(ON)/T, varied from 10.5% to 89.5%. This study also includes a questionnaire survey and analyzes the SSVEPs induced by different duty-cycle flickers. An 89.5% duty-cycle flicker, reported as a comfortable flicker, was adopted in a phase-tagged SSVEP system. Six subjects were asked to sequentially input a sequence of cursor commands with the 25.08-bits/min ITR.

  12. Effect of thermal cycling and disinfection on microhardness of acrylic resin denture base.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Dos Santos, Daniela Micheline; Baptista, Gabriella Trunckle; Moreno, Amália; Andreotti, Agda Marobo; Dekon, Stéfan Fiuza de Carvalho

    2013-04-01

    The purpose of this study was to investigate the effect of thermal cycling and disinfection on the microhardness of acrylic resins denture base. Four different brands of acrylic resins were evaluated: Onda Cryl, QC 20, Classico and Lucitone. Each brand of acrylic resin was divided into four groups (n = 7) according to the disinfection method (microwave, Efferdent, 4% chlorhexidine and 1% hypochlorite). Samples were disinfected during 60 days. Before and after disinfection, samples were thermal cycled between 5-55 °C with 30-s dwell times for 1000 cycles. The microhardness was measured using a microhardener, at baseline (B), after first thermal cycling (T1), after disinfection (D) and after second thermal cycling (T2). The microhardness values of all groups reduced over time. QC-20 acrylic resin exhibited the lowest microhardness values. At B and T1 periods, the acrylic resins exhibited statistically greater microhardness values when compared to D and T2 periods. It can be concluded that the microhardness values of the acrylic resins denture base were affected by the thermal cycling and disinfection procedures. However, all microhardness values obtained herein are within acceptable clinical limits for the acrylic resins.

  13. Sulphation of CaO-Based Sorbent Modified in CO2 Looping Cycles

    Science.gov (United States)

    Manovic, Vasilije; Anthony, Edward J.; Loncarevic, Davor

    CaO-based looping cycles for CO2 capture at high temperatures are based on cyclical carbonation of CaO and regeneration of CaCO3. The main limitation of natural sorbents is the loss of carrying capacity with increasing numbers of reaction cycles, resulting in spent sorbent ballast. Use of spent sorbent from CO2 looping cycles for SO2 capture is a possible solution investigated in this study. Three limestones were investigated: Kelly Rock (Canada), La Blanca (Spain) and Katowice (Poland). Carbonation/calcination cycles were performed in a tube furnace with original limestones and samples thermally pretreated for different times (i.e., sintered). The spent sorbent samples were sulphated in a thermogravimetric analyzer. Changes in the resulting pore structure were then investigated using mercury porosimetry. Final conversions of both spent and pretreated sorbents after longer sulphation times were comparable or higher than those observed for the original sorbents. Maximum sulphation levels strongly depend on sorbent porosity and pore surface area. The shrinkage of sorbent particles during calcination/cycling resulted in a loss of sorbent porosity (≤48%), which corresponds to maximum sulphation levels ˜55% for spent Kelly Rock and Katowice. However, this is ˜10% higher than for the original samples. By contrast, La Blanca limestone had more pronounced particle shrinkage during pretreatment and cycling, leading to lower porosity, Katowice samples final conversions are determined by the total pore volume available for the bulky CaSO4 product.

  14. Combined GnRH-agonist and human chorionic gonadotropin trigger improves ICSI cycle outcomes in patients with history of poor fertilization.

    Science.gov (United States)

    Elias, Rony T; Pereira, Nigel; Artusa, Lisa; Kelly, Amelia G; Pasternak, Monica; Lekovich, Jovana P; Palermo, Gianpiero D; Rosenwaks, Zev