Computational Fluid Dynamics Analysis Method Developed for Rocket-Based Combined Cycle Engine Inlet

Science.gov (United States)

1997-01-01

Renewed interest in hypersonic propulsion systems has led to research programs investigating combined cycle engines that are designed to operate efficiently across the flight regime. The Rocket-Based Combined Cycle Engine is a propulsion system under development at the NASA Lewis Research Center. This engine integrates a high specific impulse, low thrust-to-weight, airbreathing engine with a low-impulse, high thrust-to-weight rocket. From takeoff to Mach 2.5, the engine operates as an air-augmented rocket. At Mach 2.5, the engine becomes a dual-mode ramjet; and beyond Mach 8, the rocket is turned back on. One Rocket-Based Combined Cycle Engine variation known as the "Strut-Jet" concept is being investigated jointly by NASA Lewis, the U.S. Air Force, Gencorp Aerojet, General Applied Science Labs (GASL), and Lockheed Martin Corporation. Work thus far has included wind tunnel experiments and computational fluid dynamics (CFD) investigations with the NPARC code. The CFD method was initiated by modeling the geometry of the Strut-Jet with the GRIDGEN structured grid generator. Grids representing a subscale inlet model and the full-scale demonstrator geometry were constructed. These grids modeled one-half of the symmetric inlet flow path, including the precompression plate, diverter, center duct, side duct, and combustor. After the grid generation, full Navier-Stokes flow simulations were conducted with the NPARC Navier-Stokes code. The Chien low-Reynolds-number k-e turbulence model was employed to simulate the high-speed turbulent flow. Finally, the CFD solutions were postprocessed with a Fortran code. This code provided wall static pressure distributions, pitot pressure distributions, mass flow rates, and internal drag. These results were compared with experimental data from a subscale inlet test for code validation; then they were used to help evaluate the demonstrator engine net thrust.

Studies of a Combined-Cycle Engine

OpenAIRE

苅田, 丈士; KANDA, Takeshi

2003-01-01

For a Single-Stage-to-Orbit (SSTO) aerospace plane (Fig.1), several engines will be necessary to reach orbit. The combined-cycle engine incorporates several operational modes in a single engine. Study of the combined cycle engine has a long history, and several kinds of such engines have been proposed and studied. When several engines are mounted on a vehicle, each engine of the system will show a performance higher than that of the combined cycle engine. However, during the operation of one ...

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.

Preliminary analysis of combined cycle of modular high-temperature gas cooled reactor

International Nuclear Information System (INIS)

Baogang, Z.; Xiaoyong, Y.; Jie, W.; Gang, Z.; Qian, S.

2015-01-01

Modular high-temperature gas cooled reactor (HTGR) is known as one of the most advanced nuclear reactors because of its inherent safety and high efficiency. The power conversion system of HTGR can be steam turbine based on Rankine cycle or gas turbine based on Brayton cycle respectively. The steam turbine system is mature and the gas turbine system has high efficiency but under development. The Brayton-Rankine combined cycle is an effective way to further promote the efficiency. This paper investigated the performance of combined cycle from the viewpoint of thermodynamics. The effect of non-dimensional parameters on combined cycle’s efficiency, such as temperature ratio, compression ratio, efficiency of compressor, efficiency of turbine, was analyzed. Furthermore, the optimal parameters to achieve highest efficiency was also given by this analysis under engineering constraints. The conclusions could be helpful to the design and development of combined cycle of HTGR. (author)

A combined cycle utilizing LNG and low-temperature solar energy

International Nuclear Information System (INIS)

Rao, Wen-Ji; Zhao, Liang-Ju; Liu, Chao; Zhang, Mo-Geng

2013-01-01

This paper has proposed a combined cycle, in which low-temperature solar energy and cold energy of liquefied natural gas (LNG) can be effectively utilized together. Comparative analysis based on a same net work output between the proposed combined cycle and separated solar ORC and LNG vapor system has been done. The results show that, for the combined cycle, a decrease of nearly 82.2% on the area of solar collector is obtained and the area of heat exchanger decreases by 31.7%. Moreover, exergy efficiency is higher than both two separated systems. This work has also dealt with the thermodynamic analyses for the proposed cycle. The results show that R143a followed by propane and propene emerges as most suitable fluid. Moreover, with a regenerator added in the cycle, performance improvement is obtained for the reduction on area of solar collector and increase on system efficiency and exergy efficiency. -- Highlights: • A combined cycle utilizing low-temperature solar energy and LNG together is proposed. • Five objection functions are used to decide the best working fluids. • Cycle with a regenerator has good performance

Three Dimensional Numerical Simulation of Rocket-based Combined-cycle Engine Response During Mode Transition Events

Science.gov (United States)

Edwards, Jack R.; McRae, D. Scott; Bond, Ryan B.; Steffan, Christopher (Technical Monitor)

2003-01-01

The GTX program at NASA Glenn Research Center is designed to develop a launch vehicle concept based on rocket-based combined-cycle (RBCC) propulsion. Experimental testing, cycle analysis, and computational fluid dynamics modeling have all demonstrated the viability of the GTX concept, yet significant technical issues and challenges still remain. Our research effort develops a unique capability for dynamic CFD simulation of complete high-speed propulsion devices and focuses this technology toward analysis of the GTX response during critical mode transition events. Our principal attention is focused on Mode 1/Mode 2 operation, in which initial rocket propulsion is transitioned into thermal-throat ramjet propulsion. A critical element of the GTX concept is the use of an Independent Ramjet Stream (IRS) cycle to provide propulsion at Mach numbers less than 3. In the IRS cycle, rocket thrust is initially used for primary power, and the hot rocket plume is used as a flame-holding mechanism for hydrogen fuel injected into the secondary air stream. A critical aspect is the establishment of a thermal throat in the secondary stream through the combination of area reduction effects and combustion-induced heat release. This is a necessity to enable the power-down of the rocket and the eventual shift to ramjet mode. Our focus in this first year of the grant has been in three areas, each progressing directly toward the key initial goal of simulating thermal throat formation during the IRS cycle: CFD algorithm development; simulation of Mode 1 experiments conducted at Glenn's Rig 1 facility; and IRS cycle simulations. The remainder of this report discusses each of these efforts in detail and presents a plan of work for the next year.

Combined-cycle plants

International Nuclear Information System (INIS)

Valenti, M.

1991-01-01

This paper reports that as tougher emissions standards take hold throughout the industrialized world, manufacturers such as GE, Siemens, Foster Wheeler, and Asea Brown Boveri are designing advanced combined-cycle equipment that offers improved environmental performance without sacrificing power efficiency

The History and Promise of Combined Cycle Engines for Access to Space Applications

Science.gov (United States)

Clark, Casie

2010-01-01

For the summer of 2010, I have been working in the Aerodynamics and Propulsion Branch at NASA Dryden Flight Research Center studying combined-cycle engines, a high speed propulsion concept. Combined cycle engines integrate multiple propulsion systems into a single engine capable of running in multiple modes. These different modes allow the engine to be extremely versatile and efficient in varied flight conditions. The two most common types of combined cycle engines are Rocket-Based Combined Cycle (RBCC) and Turbine Based Combined Cycle (TBCC). The RBCC essentially combines a rocket and ramjet engine, while the TBCC integrates a turbojet and ramjet1. These two engines are able to switch between different propulsion modes to achieve maximum performance. Extensive conceptual and ground test studies of RBCC engines have been undertaken; however, an RBCC engine has never, to my knowledge, been demonstrated in flight. RBCC engines are of particular interest because they could potentially power a reusable launch vehicle (RLV) into space. The TBCC has been flight tested and shown to be effective at reaching supersonic speeds, most notably in the SR-71 Blackbird2.

Gas--steam turbine combined cycle power plants

Energy Technology Data Exchange (ETDEWEB)

Christian, J.E.

1978-10-01

The purpose of this technology evaluation is to provide performance and cost characteristics of the combined gas and steam turbine, cycle system applied to an Integrated Community Energy System (ICES). To date, most of the applications of combined cycles have been for electric power generation only. The basic gas--steam turbine combined cycle consists of: (1) a gas turbine-generator set, (2) a waste-heat recovery boiler in the gas turbine exhaust stream designed to produce steam, and (3) a steam turbine acting as a bottoming cycle. Because modification of the standard steam portion of the combined cycle would be necessary to recover waste heat at a useful temperature (> 212/sup 0/F), some sacrifice in the potential conversion efficiency is necessary at this temperature. The total energy efficiency ((electric power + recovered waste heat) divided by input fuel energy) varies from about 65 to 73% at full load to 34 to 49% at 20% rated electric power output. Two major factors that must be considered when installing a gas--steam turbine combines cycle are: the realiability of the gas turbine portion of the cycle, and the availability of liquid and gas fuels or the feasibility of hooking up with a coal gasification/liquefaction process.

A combined thermodynamic cycle based on methanol dissociation for IC (internal combustion) engine exhaust heat recovery

International Nuclear Information System (INIS)

Fu, Jianqin; Liu, Jingping; Xu, Zhengxin; Ren, Chengqin; Deng, Banglin

2013-01-01

In this paper, a novel approach for exhaust heat recovery was proposed to improve IC (internal combustion) engine fuel efficiency and also to achieve the goal for direct usage of methanol as IC engine fuel. An open organic Rankine cycle system using methanol as working medium is coupled to IC engine exhaust pipe for exhaust heat recovery. In the bottom cycle, the working medium first undergoes dissociation and expansion processes, and is then directed back to IC engine as fuel. As the external bottom cycle and the IC engine main cycle are combined together, this scheme forms a combined thermodynamic cycle. Then, this concept was applied to a turbocharged engine, and the corresponding simulation models were built for both of the external bottom cycle and the IC engine main cycle. On this basis, the energy saving potential of this combined cycle was estimated by parametric analyses. Compared to the methanol vapor engine, IC engine in-cylinder efficiency has an increase of 1.4–2.1 percentage points under full load conditions, while the external bottom cycle can increase the fuel efficiency by 3.9–5.2 percentage points at the working pressure of 30 bar. The maximum improvement to the IC engine global fuel efficiency reaches 6.8 percentage points. - Highlights: • A combined thermodynamic cycle using methanol as working medium for IC engine exhaust heat recovery is proposed. • The external bottom cycle of exhaust heat recovery and IC engine working cycle are combined together. • IC engine fuel efficiency could be improved from both in-cylinder working cycle and external bottom cycle. • The maximum improvement to the IC engine global fuel efficiency reaches 6.8 percentage points at full load

Parametric-based thermodynamic analysis of organic Rankine cycle as bottoming cycle for combined-cycle power plant

International Nuclear Information System (INIS)

Qureshi, S.; Memon, A.G.; Abbasi, A.F.

2017-01-01

In Pakistan, the thermal efficiency of the power plants is low because of a huge share of fuel energy is dumped into the atmosphere as waste heat. The ORC (Organic Rankine Cycle) has been revealed as one of the promising technologies to recover waste heat to enhance the thermal efficiency of the power plant. In current work, ORC is proposed as a second bottoming cycle for existing CCPP (Combined Cycle Power Plant). In order to assess the efficiency of the plant, a thermodynamic model is developed in the ESS (Engineering Equation Solver) software. The developed model is used for parametric analysis to assess the effects of various operating parameters on the system performance. The analysis of results shows that the integration of ORC system with existing CCPP system enhances the overall power output in the range of 150.5-154.58 MW with 0.24-5% enhancement in the efficiency depending on the operating conditions. During the parametric analysis of ORC, it is observed that inlet pressure of the turbine shows a significant effect on the performance of the system as compared to other operating parameters. (author)

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.

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)

Computational Fluid Dynamic Modeling of Rocket Based Combined Cycle Engine Flowfields

Science.gov (United States)

Daines, Russell L.; Merkle, Charles L.

1994-01-01

Computational Fluid Dynamic techniques are used to study the flowfield of a fixed geometry Rocket Based Combined Cycle engine operating in rocket ejector mode. Heat addition resulting from the combustion of injected fuel causes the subsonic engine flow to choke and go supersonic in the slightly divergent combustor-mixer section. Reacting flow computations are undertaken to predict the characteristics of solutions where the heat addition is determined by the flowfield. Here, adaptive gridding is used to improve resolution in the shear layers. Results show that the sonic speed is reached in the unheated portions of the flow first, while the heated portions become supersonic later. Comparison with results from another code show reasonable agreement. The coupled solutions show that the character of the combustion-based thermal choking phenomenon can be controlled reasonably well such that there is opportunity to optimize the length and expansion ratio of the combustor-mixer.

Technical comparison between Integrated Gasification Combined Cycle (IGCC) and Natural Gas Combined Cycle (NGCC) power plants

Energy Technology Data Exchange (ETDEWEB)

Ortiz, Pablo Andres Silva; Venturini, Osvaldo Jose; Lora, Electo Eduardo Silva [Federal University of Itajuba - UNIFEI, MG (Brazil). Excellence Group in Thermal Power and Distributed Generation - NEST], e-mails: osvaldo@unifei.edu.br, electo@unifei.edu.br

2010-07-01

Among the emerging clean coal technologies for power generation, Integrated Gasification Combined Cycle (IGCC) and Natural Gas Combined Cycle (NGCC) systems are receiving considerable attention as a potentially attractive option to reduce the emissions of greenhouse gases (GHG). The main reason is because these systems has high efficiency and low emissions in comparison with traditional power generation plants. Currently in IGCC and NGCC systems at demonstration stage is been considered to implement CCS technology. CO{sub 2} emissions can be avoided in a gasification-based power plant because by transferring almost all carbon compounds to CO{sub 2} through the water gas shift (WGS) reaction, then removing the CO{sub 2} before it is diluted in the combustion stage. The aim of this study is to compare the technical performance of an IGCC system that uses Brazilian coal and petroleum coke as fuel with a NGCC system, with the same fixed output power of 450 MW. The first section of this paper presents the plant configurations of IGCC systems. The following section presents an analysis of NGCC technology. (author)

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

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.

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.

A combined thermodynamic cycle used for waste heat recovery of internal combustion engine

International Nuclear Information System (INIS)

He, Maogang; Zhang, Xinxin; Zeng, Ke; Gao, Ke

2011-01-01

In this paper, we present a steady-state experiment, energy balance and exergy analysis of exhaust gas in order to improve the recovery of the waste heat of an internal combustion engine (ICE). Considering the different characteristics of the waste heat of exhaust gas, cooling water, and lubricant, a combined thermodynamic cycle for waste heat recovery of ICE is proposed. This combined thermodynamic cycle consists of two cycles: the organic Rankine cycle (ORC), for recovering the waste heat of lubricant and high-temperature exhaust gas, and the Kalina cycle, for recovering the waste heat of low-temperature cooling water. Based on Peng–Robinson (PR) equation of state (EOS), the thermodynamic parameters in the high-temperature ORC were calculated and determined via an in-house computer program. Suitable working fluids used in high-temperature ORC are proposed and the performance of this combined thermodynamic cycle is analyzed. Compared with the traditional cycle configuration, more waste heat can be recovered by the combined cycle introduced in this paper. -- Highlights: ► We study the energy balance of fuel in internal combustion engine. ► Heat recovery effect of exhaust gas is good when ICE is at a high-load condition. ► We propose a new combined thermodynamic cycle for waste heat of ICE. ► The combined cycle has a higher recovery efficiency than previous configurations.

Analysis of a combined Rankine-vapour-compression refrigeration cycle

International Nuclear Information System (INIS)

Aphornratana, Satha; Sriveerakul, Thanarath

2010-01-01

This paper describes a theoretical analysis of a heat-powered refrigeration cycle, a combined Rankine-vapour-compression refrigeration cycle. This refrigeration cycle combines an Organic Rankine Cycle and a vapour-compression cycle. The cycle can be powered by low grade thermal energy as low as 60 deg. C and can produce cooling temperature as low as -10 deg. C. In the analysis, two combined Rankine-vapour-compression refrigeration cycles were investigated: the system with R22 and the system with R134a. Calculated COP values between 0.1 and 0.6 of both the systems were found.

Optimum design and thermodynamic analysis of a gas turbine and ORC combined cycle with recuperators

International Nuclear Information System (INIS)

Cao, Yue; Gao, Yike; Zheng, Ya; Dai, Yiping

2016-01-01

Highlights: • A GT-ORC combined cycle with recuperators was designed. • The effect of the ORC turbine inlet pressure on the combined cycle was examined. • Toluene was a more suitable working fluid for the GT-ORC combined cycle. • The GT-ORC combined cycle performed better than the GT-Rankine combined cycle. • The sensitivity analysis to the ambient temperature was completed. - Abstract: Gas turbines are widely used in distributed power generation because of their high efficiency, low pollution and low operational cost. To further utilize the waste heat from gas turbines, an organic Rankine cycle (ORC) was proposed as the bottoming cycle for gas turbines in this paper. Two recuperators were coupled with the combined cycle to increase the thermal efficiency, and aromatics were chosen as the working fluid for the bottoming cycle. This paper focused on the optimum design and thermodynamic analysis of the gas turbine and ORC (GT-ORC) combined cycle. Results showed that the net power and thermal efficiency of the ORC increased with the ORC turbine inlet pressure and achieved optimum values at a specific pressure based on the optimum criteria. Furthermore, compared with the GT-Rankine combined cycle, the GT-ORC combined cycle had better thermodynamic performance. Toluene was a more suitable working fluid for the GT-ORC combined cycle. Moreover, ambient temperature sensitivity simulations concluded that the GT-ORC combined cycle had a maximum thermal efficiency and the combined cycle net power was mainly determined by the topping gas turbine cycle.

Multidisciplinary design of a rocket-based combined cycle SSTO launch vehicle using Taguchi methods

Science.gov (United States)

Olds, John R.; Walberg, Gerald D.

1993-01-01

Results are presented from the optimization process of a winged-cone configuration SSTO launch vehicle that employs a rocket-based ejector/ramjet/scramjet/rocket operational mode variable-cycle engine. The Taguchi multidisciplinary parametric-design method was used to evaluate the effects of simultaneously changing a total of eight design variables, rather than changing them one at a time as in conventional tradeoff studies. A combination of design variables was in this way identified which yields very attractive vehicle dry and gross weights.

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

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.

Critical review of the first-law efficiency in different power combined cycle architectures

International Nuclear Information System (INIS)

Iglesias Garcia, Steven; Ferreiro Garcia, Ramon; Carbia Carril, Jose; Iglesias Garcia, Denis

2017-01-01

Highlights: • The adiabatic expansion based TC can improve the energy efficiency of CCs. • A revolutionary TC can be a starting point to develop high-performance CCs. • A theoretical thermal efficiency of 83.7% was reached in a Nuclear Power Plant using a TC as bottoming cycle. - Abstract: This critical review explores the potential of an innovative trilateral thermodynamic cycle used to transform low-grade heat into mechanical work and compares its performance with relevant traditional thermodynamic cycles in combined cycles. The aim of this work is to show that combined cycles use traditional low efficiency power cycles in their bottoming cycle, and to evaluate theoretically the implementation of alternative power bottoming cycles. Different types of combined cycles have been reviewed, highlighting their relevant characteristics. The efficiencies of power plants using combined cycles are reviewed and compared. The relevance of researching thermodynamic cycles for combined cycle applications is that a vast amount of heat energy is available at negligible cost in the bottoming cycle of a combined cycle, with the drawback that existing thermal cycles cannot make efficient use of such available low temperature heat due to their low efficiency. The first-law efficiency is used as a parameter to compare and suggest improvements in the combined cycles (CCs) reviewed. The analysis shows that trilateral cycles using closed processes are by far the most efficient published thermal cycles for combined cycles to transform low-grade heat into mechanical work. An innovative trilateral bottoming cycle is proposed to show that the application of non-traditional power cycles can increase significantly the first-law efficiency of CCs. The highest first-law efficiencies achieved are: 85.55% in a CC using LNG cool, 73.82% for a transport vehicle CC, 74.40% in a marine CC, 83.07% in a CC for nuclear power plants, 73.82% in a CC using Brayton and Rankine cycles, 78.31% in a CC

Study of combined cycle engine for aerospace plane

OpenAIRE

苅田, 丈士; KANDA, Takeshi; 工藤, 賢司; KUDO, Kenji

2002-01-01

At the Ramjet Propulsion Research Center, the scramjet engine for an aerospace plane has been studied. Other engines are required for the plane to go into orbit. Recently, a combined cycle engine including scramjet mode has been also studied to complete the engine system for the plane. The scramjet and the combined cycle engine are most effective with application to the Single-Stage-to-Orbit (SSTO) aerospace plane, as shown in Figure 1. Recent activity on the combined cycle engine and the SST...

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%.

Optimization of the rocket mode trajectory in a rocket based combined cycle (RBCC) engine powered SSTO vehicle

Science.gov (United States)

Foster, Richard W.

1989-07-01

The application of rocket-based combined cycle (RBCC) engines to booster-stage propulsion, in combination with all-rocket second stages in orbital-ascent missions, has been studied since the mid-1960s; attention is presently given to the case of the 'ejector scramjet' RBCC configuration's application to SSTO vehicles. While total mass delivered to initial orbit is optimized at Mach 20, payload delivery capability to initial orbit optimizes at Mach 17, primarily due to the reduction of hydrogen fuel tankage structure, insulation, and thermal protection system weights.

The reliability of integrated gasification combined cycle (IGCC) power generation units

Energy Technology Data Exchange (ETDEWEB)

Higman, C.; DellaVilla, S.; Steele, B. [Syngas Consultants Ltd. (United Kingdom)

2006-07-01

This paper presents two interlinked projects aimed at supporting the improvement of integrated gasification combined cycle (IGCC) reliability. The one project comprises the extension of SPS's existing ORAP (Operational Reliability Analysis Program) reliability, availability and maintainability (RAM) tracking technology from its existing base in natural gas open and combined cycle operations into IGCC. The other project is using the extended ORAP database to evaluate performance data from existing plants. The initial work has concentrated on evaluating public domain data on the performance of gasification based power and chemical plants. This is being followed up by plant interviews in some 20 plants to verify and expand the database on current performance. 23 refs., 8 figs., 2 tabs.

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

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

Combined cycle power plant with integrated low temperature heat (LOTHECO)

International Nuclear Information System (INIS)

Kakaras, E.; Doukelis, A.; Leithner, R.; Aronis, N.

2004-01-01

The major driver to enhance the efficiency of the simple gas turbine cycle has been the increase in process conditions through advancements in materials and cooling methods. Thermodynamic cycle developments or cycle integration are among the possible ways to further enhance performance. The current paper presents the possibilities and advantages from the LOTHECO natural gas-fired combined cycle concept. In the LOTHECO cycle, low-temperature waste heat or solar heat is used for the evaporation of injected water droplets in the compressed air entering the gas turbine's combustion chamber. Following a description of this innovative cycle, its advantages are demonstrated by comparison between different gas turbine power generation systems for small and large-scale applications, including thermodynamic and economic analysis. A commercial gas turbine (ALSTOM GT10C) has been selected and computed with the heat mass balance program ENBIPRO. The results from the energy analysis are presented and the features of each concept are discussed. In addition, the exergy analysis provides information on the irreversibilities of each process and suggested improvements. Finally, the economic analysis reveals that the combined cycle plant with a heavy-duty gas turbine is the most efficient and economic way to produce electricity at base load. However, on a smaller scale, innovative designs, such as the LOTHECO concept, are required to reach the same level of performance at feasible costs

Aero-Thermo-Structural Analysis of Inlet for Rocket Based Combined Cycle Engines

Science.gov (United States)

Shivakumar, K. N.; Challa, Preeti; Sree, Dave; Reddy, Dhanireddy R. (Technical Monitor)

2000-01-01

NASA has been developing advanced space transportation concepts and technologies to make access to space less costly. One such concept is the reusable vehicles with short turn-around times. The NASA Glenn Research Center's concept vehicle is the Trailblazer powered by a rocket-based combined cycle (RBCC) engine. Inlet is one of the most important components of the RBCC engine. This paper presents fluid flow, thermal, and structural analysis of the inlet for Mach 6 free stream velocity for fully supersonic and supercritical with backpressure conditions. The results concluded that the fully supersonic condition was the most severe case and the largest stresses occur in the ceramic matrix composite layer of the inlet cowl. The maximum tensile and the compressive stresses were at least 3.8 and 3.4, respectively, times less than the associated material strength.

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

Combined rankine and vapor compression cycles

Science.gov (United States)

Radcliff, Thomas D.; Biederman, Bruce P.; Brasz, Joost J.

2005-04-19

An organic rankine cycle system is combined with a vapor compression cycle system with the turbine generator of the organic rankine cycle generating the power necessary to operate the motor of the refrigerant compressor. The vapor compression cycle is applied with its evaporator cooling the inlet air into a gas turbine, and the organic rankine cycle is applied to receive heat from a gas turbine exhaust to heat its boiler within one embodiment, a common condenser is used for the organic rankine cycle and the vapor compression cycle, with a common refrigerant, R-245a being circulated within both systems. In another embodiment, the turbine driven generator has a common shaft connected to the compressor to thereby eliminate the need for a separate motor to drive the compressor. In another embodiment, an organic rankine cycle system is applied to an internal combustion engine to cool the fluids thereof, and the turbo charged air is cooled first by the organic rankine cycle system and then by an air conditioner prior to passing into the intake of the engine.

Combined factors effect of menstrual cycle and background noise on visual inspection task performance: a simulation-based task.

Science.gov (United States)

Wijayanto, Titis; Tochihara, Yutaka; Wijaya, Andi R; Hermawati, Setia

2009-11-01

It is well known that women are physiologically and psychologically influenced by the menstrual cycle. In addition, the presence of background noise may affect task performance. So far, it has proven difficult to describe how the menstrual cycle and background noise affect task performance; some researchers have found an increment of performance during menstruation or during the presence of noise, others found performance deterioration, while other still have reported no dominant effect either of the menstrual cycle in performance or of the presence of noise. However, no study to date has investigated the combinational effect between the menstrual cycle and the presence of background noise in task performance. Therefore, the purpose of this study was to examine the combined factor effect of menstrual cycle and background noise on visual inspection task performance indices by Signal Detection Theory (SDT) metrics: sensitivity index (d') and response criteria index (beta). For this purpose, ten healthy female students (21.5+/-1.08 years) with a regular menstrual cycle participated in this study. A VDT-based visual inspection task was used for the experiment in 3x2 factorial designs. Two factors, menstrual phase, pre-menstruation (PMS), menstruation (M), and post-menstruation (PM) and background noise, with 80 dB(A) background noise and without noise, were analyzed as the main factors in this study. The results concluded that the sensitivity index (d') of SDT was affected in all the menstrual cycle conditions (pbackground noise (pbackground noise was found in this study. On the other hand, no significant effect was observed in the subject's tendency in visual inspection, shown by beta along the menstrual cycle and the presence of background noise. According to the response criteria for each individual subject, the presence of noise affected the tendency of some subjects in detecting the object and making decision during the visual inspection task.

Exergy efficiency analysis of ORC (Organic Rankine Cycle) and ORC-based combined cycles driven by low-temperature waste heat

International Nuclear Information System (INIS)

Sun, Wenqiang; Yue, Xiaoyu; Wang, Yanhui

2017-01-01

Highlights: • ORC-ARC and ORC-ERC driven by low-temperature waste heat are investigated. • Thermodynamic models of basic ORC, ORC-ARC, and ORC-ERC are developed. • Exergy efficiencies of ORC, ORC-ARC, and ORC-ERC are parametrically simulated. • Suitable application conditions of ORC-ARC and ORC-ERC are reported. - Abstract: There is large amount of waste heat resources in industrial processes. However, most low-temperature waste heat is directly discharged into the environment. With the advantages of being energy-efficient, enabling investment-savings and being environmentally friendly, the Organic Rankine Cycle (ORC) plays an important role in recycling energy from low-temperature waste heat. In this study, the ORC system driven by industrial low-temperature waste heat was analyzed and optimized. The impacts of the operational parameters, including evaporation temperature, condensation temperature, and degree of superheat, on the thermodynamic performances of ORC system were conducted, with R113 used as the working fluid. In addition, the ORC-based cycles, combined with the Absorption Refrigeration Cycle (ARC) and the Ejector Refrigeration Cycle (ERC), were investigated to recover waste heat from low-temperature flue gas. The uncoupled ORC-ARC and ORC-ERC systems can generate both power and cooling for external uses. The exergy efficiency of both systems decreases with the increase of the evaporation temperature of the ORC. The net power output, the refrigerating capacity and the resultant exergy efficiency of the uncoupled ORC-ARC are all higher than those of the ORC-ERC for the evaporation temperature of the basic ORC >153 °C, in the investigated application. Finally, suitable application conditions over other temperature ranges are also given.

Combined Brayton-JT cycles with refrigerants for natural gas liquefaction

Science.gov (United States)

Chang, Ho-Myung; Park, Jae Hoon; Lee, Sanggyu; Choe, Kun Hyung

2012-06-01

Thermodynamic cycles for natural gas liquefaction with single-component refrigerants are investigated under a governmental project in Korea, aiming at new processes to meet the requirements on high efficiency, large capacity, and simple equipment. Based upon the optimization theory recently published by the present authors, it is proposed to replace the methane-JT cycle in conventional cascade process with a nitrogen-Brayton cycle. A variety of systems to combine nitrogen-Brayton, ethane-JT and propane-JT cycles are simulated with Aspen HYSYS and quantitatively compared in terms of thermodynamic efficiency, flow rate of refrigerants, and estimated size of heat exchangers. A specific Brayton-JT cycle is suggested with detailed thermodynamic data for further process development. The suggested cycle is expected to be more efficient and simpler than the existing cascade process, while still taking advantage of easy and robust operation with single-component refrigerants.

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.

Diagnostic system for combine cycle power plant

International Nuclear Information System (INIS)

Shimizu, Yujiro; Nomura, Masumi; Tanaka, Satoshi; Ito, Ryoji; Kita, Yoshiyuki

2000-01-01

We developed the Diagnostic System for Combined Cycle Power Plant which enables inexperienced operators as well as experienced operators to cope with abnormal conditions of Combined Cycle Power Plant. The features of this system are the Estimate of Emergency Level for Operation and the Prediction of Subsequent Abnormality, adding to the Diagnosis of Cause and the Operation Guidance. Moreover in this system, Diagnosis of Cause was improved by using our original method and support screens can be displayed for educational means in normal condition as well. (Authors)

Combined heat and power considered as a virtual steam cycle heat pump

International Nuclear Information System (INIS)

Lowe, Robert

2011-01-01

The first aim of this paper is to shed light on the thermodynamic reasons for the practical pursuit of low temperature operation by engineers involved in the design and the operation of combined heat and power (CHP) and district heating (DH) systems. The paper shows that the steam cycle of a combined heat and power generator is thermodynamically equivalent to a conventional steam cycle generator plus an additional virtual steam cycle heat pump. This apparently novel conceptualisation leads directly to (i) the observed sensitivity of coefficient of performance of CHP to supply and return temperatures in associated DH systems, and (ii) the conclusion that the performance of CHP will tend to be significantly higher than real heat pumps operating at similar temperatures. The second aim, which is pursued more qualitatively, is to show that the thermodynamic performance advantages of CHP are consistent with the goal of deep, long-term decarbonisation of industrialised economies. As an example, estimates are presented, which suggest that CHP based on combined-cycle gas turbines with carbon capture and storage has the potential to reduce the carbon intensity of delivered heat by a factor of ∼30, compared with a base case of natural gas-fired condensing boilers. - Highlights: → Large-scale CHP systems are thermodynamically equivalent to virtual steam cycle heat pumps. → COPs of such virtual heat pumps are necessarily better than the Carnot limit for real heat pumps. → COPs can approach 9 for plant matched to district heating systems with flow temperatures of 90 deg. C. → CHP combined with CCGT and CCS can reduce the carbon intensity of delivered heat ∼30-fold.

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

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

Study on economic potential of nuclear-gas combined cycle power generation in Chinese market

International Nuclear Information System (INIS)

Zhou Zhiwei; Bian Zhiqiang; Yang Mengjia

2004-01-01

Facing the challenges of separation of electric power plant and grid, and the deregulation of Chinese electricity supplying market in near future, nuclear power plants mainly operated as based load at the present regulated market should look for new operation mode. The economics of electric generation with nuclear-natural gas combined cycle is studied based on current conditions of natural gas and nuclear power plants in China. The results indicate that the technology development of nuclear-natural gas combined cycle for power generation is of potential prospects in Chinese electric market. (authors)

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 .

Turbulent Mixing of Primary and Secondary Flow Streams in a Rocket-Based Combined Cycle Engine

Science.gov (United States)

Cramer, J. M.; Greene, M. U.; Pal, S.; Santoro, R. J.; Turner, Jim (Technical Monitor)

2002-01-01

This viewgraph presentation gives an overview of the turbulent mixing of primary and secondary flow streams in a rocket-based combined cycle (RBCC) engine. A significant RBCC ejector mode database has been generated, detailing single and twin thruster configurations and global and local measurements. On-going analysis and correlation efforts include Marshall Space Flight Center computational fluid dynamics modeling and turbulent shear layer analysis. Potential follow-on activities include detailed measurements of air flow static pressure and velocity profiles, investigations into other thruster spacing configurations, performing a fundamental shear layer mixing study, and demonstrating single-shot Raman measurements.

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.

The future of integrated coal gasification combined cycle power plants

International Nuclear Information System (INIS)

Mueller, R.; Termuehlen, H.

1991-01-01

This paper examines the future of integrated coal gasification combined cycle (IGCC) power plants as affected by various technical, economical and environmental trends in power generation. The topics of the paper include a description of natural gas-fired combined cycle power plants, IGCC plants, coal gasifier concepts, integration of gasifiers into combined cycle power plants, efficiency, environmental impacts, co-products of IGCC power plants, economics of IGCC power plants, and a review of IGCC power plant projects

First image from a combined positron emission tomography and field-cycled MRI system.

Science.gov (United States)

Bindseil, Geron A; Gilbert, Kyle M; Scholl, Timothy J; Handler, William B; Chronik, Blaine A

2011-07-01

Combining positron emission tomography and MRI modalities typically requires using either conventional MRI with a MR-compatible positron emission tomography system or a modified MR system with conventional positron emission tomography. A feature of field-cycled MRI is that all magnetic fields can be turned off rapidly, enabling the use of conventional positron emission tomography detectors based on photomultiplier tubes. In this demonstration, two photomultiplier tube-based positron emission tomography detectors were integrated with a field-cycled MRI system (0.3 T/4 MHz) by placing them into a 9-cm axial gap. A positron emission tomography-MRI phantom consisting of a triangular arrangement of positron-emitting point sources embedded in an onion was imaged in a repeating interleaved sequence of ∼1 sec MRI then 1 sec positron emission tomography. The first multimodality images from the combined positron emission tomography and field-cycled MRI system show no additional artifacts due to interaction between the systems and demonstrate the potential of this approach to combining positron emission tomography and MRI. Copyright © 2010 Wiley-Liss, Inc.

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.

Exergy-based method for analyzing the composition of the electricity cost generated in gas-fired combined cycle plants

Energy Technology Data Exchange (ETDEWEB)

Sarraf Borelli, Samuel Jose [Promon Engenharia Ltda., Av. Presidente Juscelino Kubitschek, 1830, Itaim, CEP:04543-900 Sao Paulo/SP (Brazil)], E-mail: sborelli@terra.com.br; Oliveira Junior, Silvio de [Environmental and Thermal Engineering Laboratory, Polytechnic School, University of Sao Paulo, Av. Prof. Luciano Gualberto, 1289, Cidade Universitaria, CEP:05508-900 Sao Paulo/SP (Brazil)], E-mail: silvio.oliveira@poli.usp.br

2008-02-15

The proposed method to analyze the composition of the cost of electricity is based on the energy conversion processes and the destruction of the exergy through the several thermodynamic processes that comprise a combined cycle power plant. The method uses thermoeconomics to evaluate and allocate the cost of exergy throughout the processes, considering costs related to inputs and investment in equipment. Although the concept may be applied to any combined cycle or cogeneration plant, this work develops only the mathematical modeling for three-pressure heat recovery steam generator (HRSG) configurations and total condensation of the produced steam. It is possible to study any nx1 plant configuration (n sets of gas turbine and HRSGs associated to one steam turbine generator and condenser) with the developed model, assuming that every train operates identically and in steady state. The presented model was conceived from a complex configuration of a real power plant, over which variations may be applied in order to adapt it to a defined configuration under study [Borelli SJS. Method for the analysis of the composition of electricity costs in combined cycle thermoelectric power plants. Master in Energy Dissertation, Interdisciplinary Program of Energy, Institute of Eletro-technical and Energy, University of Sao Paulo, Sao Paulo, Brazil, 2005 (in Portuguese)]. The variations and adaptations include, for instance, use of reheat, supplementary firing and partial load operation. It is also possible to undertake sensitivity analysis on geometrical equipment parameters.

Exergy-based method for analyzing the composition of the electricity cost generated in gas-fired combined cycle plants

Energy Technology Data Exchange (ETDEWEB)

Borelli, Samuel Jose Sarraf [Promon Engenharia Ltda., Av. Presidente Juscelino Kubitschek, 1830, Itaim, CEP:04543-900 Sao Paulo/SP (Brazil); De Oliveira Junior, Silvio [Environmental and Thermal Engineering Laboratory, Polytechnic School, University of Sao Paulo, Av. Prof. Luciano Gualberto, 1289, Cidade Universitaria, CEP:05508-900 Sao Paulo/SP (Brazil)

2008-02-15

The proposed method to analyze the composition of the cost of electricity is based on the energy conversion processes and the destruction of the exergy through the several thermodynamic processes that comprise a combined cycle power plant. The method uses thermoeconomics to evaluate and allocate the cost of exergy throughout the processes, considering costs related to inputs and investment in equipment. Although the concept may be applied to any combined cycle or cogeneration plant, this work develops only the mathematical modeling for three-pressure heat recovery steam generator (HRSG) configurations and total condensation of the produced steam. It is possible to study any n x 1 plant configuration (n sets of gas turbine and HRSGs associated to one steam turbine generator and condenser) with the developed model, assuming that every train operates identically and in steady state. The presented model was conceived from a complex configuration of a real power plant, over which variations may be applied in order to adapt it to a defined configuration under study [Borelli SJS. Method for the analysis of the composition of electricity costs in combined cycle thermoelectric power plants. Master in Energy Dissertation, Interdisciplinary Program of Energy, Institute of Eletro-technical and Energy, University of Sao Paulo, Sao Paulo, Brazil, 2005 (in Portuguese)]. The variations and adaptations include, for instance, use of reheat, supplementary firing and partial load operation. It is also possible to undertake sensitivity analysis on geometrical equipment parameters. (author)

Exergy-based method for analyzing the composition of the electricity cost generated in gas-fired combined cycle plants

International Nuclear Information System (INIS)

Sarraf Borelli, Samuel Jose; Oliveira Junior, Silvio de

2008-01-01

The proposed method to analyze the composition of the cost of electricity is based on the energy conversion processes and the destruction of the exergy through the several thermodynamic processes that comprise a combined cycle power plant. The method uses thermoeconomics to evaluate and allocate the cost of exergy throughout the processes, considering costs related to inputs and investment in equipment. Although the concept may be applied to any combined cycle or cogeneration plant, this work develops only the mathematical modeling for three-pressure heat recovery steam generator (HRSG) configurations and total condensation of the produced steam. It is possible to study any nx1 plant configuration (n sets of gas turbine and HRSGs associated to one steam turbine generator and condenser) with the developed model, assuming that every train operates identically and in steady state. The presented model was conceived from a complex configuration of a real power plant, over which variations may be applied in order to adapt it to a defined configuration under study [Borelli SJS. Method for the analysis of the composition of electricity costs in combined cycle thermoelectric power plants. Master in Energy Dissertation, Interdisciplinary Program of Energy, Institute of Eletro-technical and Energy, University of Sao Paulo, Sao Paulo, Brazil, 2005 (in Portuguese)]. The variations and adaptations include, for instance, use of reheat, supplementary firing and partial load operation. It is also possible to undertake sensitivity analysis on geometrical equipment parameters

Rocket-Based Combined Cycle Engine Technology Development: Inlet CFD Validation and Application

Science.gov (United States)

DeBonis, J. R.; Yungster, S.

1996-01-01

A CFD methodology has been developed for inlet analyses of Rocket-Based Combined Cycle (RBCC) Engines. A full Navier-Stokes analysis code, NPARC, was used in conjunction with pre- and post-processing tools to obtain a complete description of the flow field and integrated inlet performance. This methodology was developed and validated using results from a subscale test of the inlet to a RBCC 'Strut-Jet' engine performed in the NASA Lewis 1 x 1 ft. supersonic wind tunnel. Results obtained from this study include analyses at flight Mach numbers of 5 and 6 for super-critical operating conditions. These results showed excellent agreement with experimental data. The analysis tools were also used to obtain pre-test performance and operability predictions for the RBCC demonstrator engine planned for testing in the NASA Lewis Hypersonic Test Facility. This analysis calculated the baseline fuel-off internal force of the engine which is needed to determine the net thrust with fuel on.

Use of the 5E learning cycle model combined with problem-based learning for a fundamentals of nursing course.

Science.gov (United States)

Jun, Won Hee; Lee, Eun Ju; Park, Han Jong; Chang, Ae Kyung; Kim, Mi Ja

2013-12-01

The 5E learning cycle model has shown a positive effect on student learning in science education, particularly in courses with theory and practice components. Combining problem-based learning (PBL) with the 5E learning cycle was suggested as a better option for students' learning of theory and practice. The purpose of this study was to compare the effects of the traditional learning method with the 5E learning cycle model with PBL. The control group (n = 78) was subjected to a learning method that consisted of lecture and practice. The experimental group (n = 83) learned by using the 5E learning cycle model with PBL. The results showed that the experimental group had significantly improved self-efficacy, critical thinking, learning attitude, and learning satisfaction. Such an approach could be used in other countries to enhance students' learning of fundamental nursing. Copyright 2013, SLACK Incorporated.

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.

Exergy analysis of a combined power and cooling cycle

International Nuclear Information System (INIS)

Fontalvo, Armando; Pinzon, Horacio; Duarte, Jorge; Bula, Antonio; Quiroga, Arturo Gonzalez; Padilla, Ricardo Vasquez

2013-01-01

This paper presents a comprehensive exergy analysis of a combined power and cooling cycle which combines a Rankine and absorption refrigeration cycle by using ammonia–water mixture as working fluid. A thermodynamic model was developed in Matlab ® to find out the effect of pressure ratio, ammonia mass fraction at the absorber and turbine efficiency on the total exergy destruction of the cycle. The contribution of each cycle component on the total exergy destruction was also determined. The results showed that total exergy destruction decreases when pressure ratio increases, and reaches a maximum at x ≈ 0.5, when ammonia mass fraction is varied at absorber. Also, it was found that the absorber, the boiler and the turbine had the major contribution to the total exergy destruction of the cycle, and the increase of the turbine efficiency reduces the total exergy destruction. The effect of rectification cooling source (external and internal) on the cycle output was investigated, and the results showed that internal rectification cooling reduces the total exergy destruction of the cycle. Finally, the effect of the presence or absence of the superheater after the rectification process was determined and it was obtained that the superheated condition reduces the exergy destruction of the cycle at high turbine efficiency values. Highlights: • A parametric exergy analysis of a combined power and cooling cycle is performed. • Two scenarios for rectifier cooling (internal and external) were studied. • Internal cooling source is more exergetic efficient than external cooling source. • The absorber and boiler have the largest total exergy destruction. • Our results show that the superheater reduces the exergy destruction of the cycle

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

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...

Air bottoming cycle, an alternative to combined cycles. Final report

Energy Technology Data Exchange (ETDEWEB)

Kaikko, J. [Royal Inst. of Techn., Stockholm (Sweden). Dept. of Energy Technology

2001-10-01

In this work, the idea of Air Bottoming Cycle (ABC) has been studied. The objectives for the work have been to establish an understanding of the concept for power and heat generation as well as to find - if possible - feasible concepts for future use in the Swedish energy system. Combined cycle in power generation is an established technology. In the conventional combined cycle, a gas turbine works as a topping cycle together with the steam (Rankine) bottoming cycle. In the ABC the steam bottoming cycle is replaced with a gas turbine (Brayton) bottoming cycle having air as a working fluid. The two gas turbines are thermally connected over a gas-to-gas heat exchanger. This concept promises savings in weight and cost, as well as operating benefits, compared to the Rankine bottoming technology. The ABC has been modelled using a heat balance program, and a parametric study for the concept optimisation as well as for off-design analysis has been performed. Performance of the ABC has been compared to other, established technologies. A preliminary economic evaluation has been made. As a result of the study, it is clarified that the Rankine bottoming cycle with steam remains superior to the ABC as regards electrical efficiency in the medium and large power scale. For small-scale applications (<10 MW{sub e}) where the thermodynamic advantage of the Rankine cycle is not dominating any longer and its economy is burdened by the heavy investment structure, the ABC becomes the better alternative for energy utilisation. A preliminary economic evaluation shows that (at energy prices autumn 2000) the ABC is at the same level as the comparable small-scale cogeneration installations. Due to high power-to-heat ratio however, higher electricity prices will favour the ABC. One interesting feature of the ABC is that about 50% of the dissipated low-value heat from the cycle is carried by clean (sterile) air at the temperature around 200 deg C. This air can be utilised for space heating or

Exergy, exergoeconomic and environmental analyses and evolutionary algorithm based multi-objective optimization of combined cycle power plants

International Nuclear Information System (INIS)

Ahmadi, Pouria; Dincer, Ibrahim; Rosen, Marc A.

2011-01-01

A comprehensive exergy, exergoeconomic and environmental impact analysis and optimization is reported of several combined cycle power plants (CCPPs). In the first part, thermodynamic analyses based on energy and exergy of the CCPPs are performed, and the effect of supplementary firing on the natural gas-fired CCPP is investigated. The latter step includes the effect of supplementary firing on the performance of bottoming cycle and CO 2 emissions, and utilizes the first and second laws of thermodynamics. In the second part, a multi-objective optimization is performed to determine the 'best' design parameters, accounting for exergetic, economic and environmental factors. The optimization considers three objective functions: CCPP exergy efficiency, total cost rate of the system products and CO 2 emissions of the overall plant. The environmental impact in terms of CO 2 emissions is integrated with the exergoeconomic objective function as a new objective function. The results of both exergy and exergoeconomic analyses show that the largest exergy destructions occur in the CCPP combustion chamber, and that increasing the gas turbine inlet temperature decreases the CCPP cost of exergy destruction. The optimization results demonstrates that CO 2 emissions are reduced by selecting the best components and using a low fuel injection rate into the combustion chamber. -- Highlights: → Comprehensive thermodynamic modeling of a combined cycle power plant. → Exergy, economic and environmental analyses of the system. → Investigation of the role of multiobjective exergoenvironmental optimization as a tool for more environmentally-benign design.

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

Directory of Open Access Journals (Sweden)

Ravi Kumar Naradasu

2007-01-01

Full Text Available 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 aimed at optimal utilization of the flue gas recovery heat with different heat recovery steam generator configurations of single pressure and dual pressure. The combined cycle efficiency with different heat recovery steam generator configurations have been analyzed parametrically by using first law and second law of thermodynamics. It is observed that in the dual cycle high pressure steam turbine pressure must be high and low pressure steam turbine pressure must be low for better heat recovery from heat recovery steam generator.

Gas fired combined cycle plant in Singapore: energy use, GWP and cost-a life cycle approach

International Nuclear Information System (INIS)

Kannan, R.; Leong, K.C.; Osman, Ramli; Ho, H.K.; Tso, C.P.

2005-01-01

A life cycle assessment was performed to quantify the non-renewable (fossil) energy use and global warming potential (GWP) in electricity generation from a typical gas fired combined cycle power plant in Singapore. The cost of electricity generation was estimated using a life cycle cost analysis (LCCA) tool. The life cycle assessment (LCA) of a 367.5 MW gas fired combined cycle power plant operating in Singapore revealed that hidden processes consume about 8% additional energy in addition to the fuel embedded energy, and the hidden GWP is about 18%. The natural gas consumed during the operational phase accounted for 82% of the life cycle cost of electricity generation. An empirical relation between plant efficiency and life cycle energy use and GWP in addition to a scenario for electricity cost with varying gas prices and plant efficiency have been established

Rocket-Based Combined Cycle Activities in the Advanced Space Transportation Program Office

Science.gov (United States)

Hueter, Uwe; Turner, James

1999-01-01

NASA's Office of Aero-Space Technology (OAST) has established three major goals, referred to as, "The Three Pillars for Success". The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center (MSFC) in Huntsville, Ala. focuses on future space transportation technologies Under the "Access to Space" pillar. The Core Technologies Project, part of ASTP, focuses on the reusable technologies beyond those being pursued by X-33. One of the main activities over the past two and a half years has been on advancing the rocket-based combined cycle (RBCC) technologies. In June of last year, activities for reusable launch vehicle (RLV) airframe and propulsion technologies were initiated. These activities focus primarily on those technologies that support the decision to determine the path this country will take for Space Shuttle and RLV. This year, additional technology efforts in the reusable technologies will be awarded. The RBCC effort that was completed early this year was the initial step leading to flight demonstrations of the technology for space launch vehicle propulsion.

A Combined High and Low Cycle Fatigue Model for Life Prediction of Turbine Blades

Directory of Open Access Journals (Sweden)

Shun-Peng Zhu

2017-06-01

Full Text Available Combined high and low cycle fatigue (CCF generally induces the failure of aircraft gas turbine attachments. Based on the aero-engine load spectrum, accurate assessment of fatigue damage due to the interaction of high cycle fatigue (HCF resulting from high frequency vibrations and low cycle fatigue (LCF from ground-air-ground engine cycles is of critical importance for ensuring structural integrity of engine components, like turbine blades. In this paper, the influence of combined damage accumulation on the expected CCF life are investigated for turbine blades. The CCF behavior of a turbine blade is usually studied by testing with four load-controlled parameters, including high cycle stress amplitude and frequency, and low cycle stress amplitude and frequency. According to this, a new damage accumulation model is proposed based on Miner’s rule to consider the coupled damage due to HCF-LCF interaction by introducing the four load parameters. Five experimental datasets of turbine blade alloys and turbine blades were introduced for model validation and comparison between the proposed Miner, Manson-Halford, and Trufyakov-Kovalchuk models. Results show that the proposed model provides more accurate predictions than others with lower mean and standard deviation values of model prediction errors.

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

Energy Technology Data Exchange (ETDEWEB)

Lee, Sungkyu; Lee, Jieun; Kang, Suk-Hwan; Lee, Seung-Jong; Yun, Yongseung [Institute for Advanced Engineering (IAE), Gyeonggi-do (Korea, Republic of). Plant Engineering Center; Kim, Min Jung [Sungkyunkwan Univ, Gyeonggi-do (Korea, Republic of). Advanced Materials Technology Research Center

2015-07-01

The corrosion behavior of commercially available Haynes {sup registered} 230 {sup 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 {sup registered} 230 {sup 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 {sup registered} 556 {sup registered}.

Air bottoming cycle, an alternative to combined cycles. Final report

Energy Technology Data Exchange (ETDEWEB)

Kaikko, J. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Energy Technology

2002-02-01

In this work, the idea of Air Bottoming Cycle (ABC) has been studied. The objectives for the work have been to establish an understanding of the concept for power and heat generation as well as to find - if possible - feasible concepts for future use in the Swedish energy system. Combined cycle in power generation is an established technology. In the conventional combined cycle, a gas turbine works as a topping cycle together with the steam (Rankine) bottoming cycle. In the ABC the steam bottoming cycle is replaced with a gas turbine (Brayton) bottoming cycle having air as a working fluid. The two gas turbines are thermally connected over a gas-to-gas heat exchanger. This concept promises savings in weight and cost, as well as operating benefits, compared to the Rankine bottoming technology. The ABC has been modelled using a heat balance program, and a parametric study for the concept optimisation as well as for off-design analysis has been performed. Performance of the ABC has been compared to other, established technologies. A preliminary economic evaluation has been made. As a result of the study, it is clarified that the Rankine bottoming cycle with steam remains superior to the ABC as regards electrical efficiency in the medium and large power scale. For small-scale applications (<10 MW{sub e}) where the thermodynamic advantage of the Rankine cycle is not dominating any longer and its economy is burdened by the heavy investment structure, the ABC becomes the better alternative for energy utilisation. A preliminary economic evaluation shows that (at energy prices autumn 2000) the ABC is at the same level as the comparable small-scale cogeneration installations. Due to high power-to-heat ratio however, higher electricity prices will favour the ABC. One interesting feature of the ABC is that about 50% of the dissipated low-value heat from the cycle is carried by clean (sterile) air at the temperature around 200 deg C. This air can be utilised for space heating or

Towards a Life Cycle Based Chemical Alternative Assessment (LCAA)

DEFF Research Database (Denmark)

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

2017-01-01

approach combines the following elements: a) The manufacturing phase chemical inventory is based on the environmental genome of industrial products database, ensuring mass and energy balance, b) near-field exposure to consumer products during the use phase is determined based on the mass of chemical......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...

Parametric Data from a Wind Tunnel Test on a Rocket-Based Combined-Cycle Engine Inlet

Science.gov (United States)

Fernandez, Rene; Trefny, Charles J.; Thomas, Scott R.; Bulman, Mel J.

2001-01-01

A 40-percent scale model of the inlet to a rocket-based combined-cycle (RBCC) engine was tested in the NASA Glenn Research Center 1- by 1-Foot Supersonic Wind Tunnel (SWT). The full-scale RBCC engine is scheduled for test in the Hypersonic Tunnel Facility (HTF) at NASA Glenn's Plum Brook Station at Mach 5 and 6. This engine will incorporate the configuration of this inlet model which achieved the best performance during the present experiment. The inlet test was conducted at Mach numbers of 4.0, 5.0, 5.5, and 6.0. The fixed-geometry inlet consists of an 8 deg.. forebody compression plate, boundary layer diverter, and two compressive struts located within 2 parallel sidewalls. These struts extend through the inlet, dividing the flowpath into three channels. Test parameters investigated included strut geometry, boundary layer ingestion, and Reynolds number (Re). Inlet axial pressure distributions and cross-sectional Pitot-pressure surveys at the base of the struts were measured at varying back-pressures. Inlet performance and starting data are presented. The inlet chosen for the RBCC engine self-started at all Mach numbers from 4 to 6. Pitot-pressure contours showed large flow nonuniformity on the body-side of the inlet. The inlet provided adequate pressure recovery and flow quality for the RBCC cycle even with the flow separation.

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

Simulation of a combined-cycle engine

Science.gov (United States)

Vangerpen, Jon

1991-01-01

A FORTRAN computer program was developed to simulate the performance of combined-cycle engines. These engines combine features of both gas turbines and reciprocating engines. The computer program can simulate both design point and off-design operation. Widely varying engine configurations can be evaluated for their power, performance, and efficiency as well as the influence of altitude and air speed. Although the program was developed to simulate aircraft engines, it can be used with equal success for stationary and automative applications.

Technical And Economical FACTIBILITY To Apply A Combined Cycle

International Nuclear Information System (INIS)

Hernández Rangel, Elybe

2017-01-01

In the state of Falcon specifically in the peninsula of Paraguaná, there are two electric plants; GENEVAPCA and CADAFE. These companies are in charge of providing electrical power to the population, which is being affected by the increment of the population, plus the touristic development of the tax free zone. This reasons cause the systematic ration of the electrical power that as a consequence causes electrical interruptions for a long period of time. Due to this electrical plants can not cover the demand in its totality, there must be created alternative for usage of the electricity which would increment its production. The following thesis has an objective to analyze the technical and economical factibility to apply a combined cycle, with the purpose of increasing the electrical power supply and obtain a better thermodynamically performance. Such project was elaborated in four phases. The first phase contemplated the data collection related to the subject, obtaining important information to select the best option of the combined cycle. In the Second phase was executed the termination of the thermodynamically and energetically properties of the combined cycle, comparing the efficient of the simple cycle with the cycle mention before. As final phase, the project’s economical rentability was estimated for possible installation. (author)

The development and chemistry of high efficiency combined cycle plants

International Nuclear Information System (INIS)

Svoboda, Robert

1999-01-01

This paper presents a boiler concept based on the combination of a low-pressure drum-type boiler with high-pressure once-through boiler and the appropriate water/steam cycle. An all volatile treatment is used in the low-pressure boiler and oxygenated treatment for the once-through high pressure system. Impurity control is achieved by adapted system design and materials, high quality make-up, an appropriate cleanliness concept and clean-up procedures for a cold start. Cycle refreshing is realized by blowdown from the high-pressure water-separator. This concept utilizes simper and less equipment than traditional solutions, resulting in increased power plant reliability and less requirement on maintenance and on capital cost [it

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.

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...... 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...

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

Studies of an extensively axisymmetric rocket based combined cycle (RBCC) engine powered single-stage-to-orbit (SSTO) vehicle

Science.gov (United States)

Foster, Richard W.; Escher, William J. D.; Robinson, John W.

1989-01-01

The present comparative performance study has established that rocket-based combined cycle (RBCC) propulsion systems, when incorporated by essentially axisymmetric SSTO launch vehicle configurations whose conical forebody maximizes both capture-area ratio and total capture area, are capable of furnishing payload-delivery capabilities superior to those of most multistage, all-rocket launchers. Airbreathing thrust augmentation in the rocket-ejector mode of an RBCC powerplant is noted to make a major contribution to final payload capability, by comparison to nonair-augmented rocket engine propulsion systems.

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.

Rocket Based Combined Cycle Exchange Inlet Performance Estimation at Supersonic Speeds

Science.gov (United States)

Murzionak, Aliaksandr

A method to estimate the performance of an exchange inlet for a Rocket Based Combined Cycle engine is developed. This method is to be used for exchange inlet geometry optimization and as such should be able to predict properties that can be used in the design process within a reasonable amount of time to allow multiple configurations to be evaluated. The method is based on a curve fit of the shocks developed around the major components of the inlet using solutions for shocks around sharp cones and 2D estimations of the shocks around wedges with blunt leading edges. The total pressure drop across the estimated shocks as well as the mass flow rate through the exchange inlet are calculated. The estimations for a selected range of free-stream Mach numbers between 1.1 and 7 are compared against numerical finite volume method simulations which were performed using available commercial software (Ansys-CFX). The total pressure difference between the two methods is within 10% for the tested Mach numbers of 5 and below, while for the Mach 7 test case the difference is 30%. The mass flow rate on average differs by less than 5% for all tested cases with the maximum difference not exceeding 10%. The estimation method takes less than 3 seconds on 3.0 GHz single core processor to complete the calculations for a single flight condition as oppose to over 5 days on 8 cores at 2.4 GHz system while using 3D finite volume method simulation with 1.5 million elements mesh. This makes the estimation method suitable for the use with exchange inlet geometry optimization algorithm.

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.

Thermodynamic and economic analysis on geothermal integrated combined-cycle power plants

International Nuclear Information System (INIS)

Bettocchi, R.; Cantore, G.; Negri di Montenegro, G.; Gadda, E.

1992-01-01

This paper considers geothermal integrated power plants obtained matching a geothermal plant with, a two pressure level combined plant. The purpose of the paper is the evaluation of thermodynamic and economic aspects on geothermal integrated combined-cycle power plant and a comparison with conventional solutions. The results show that the integrated combined plant power is greater than the sum of combined cycle and geothermal plant powers considered separately and that the integrated plant can offer economic benefits reaching the 16% of the total capital required

Hybrid solar central receiver for combined cycle power plant

Science.gov (United States)

Bharathan, Desikan; Bohn, Mark S.; Williams, Thomas A.

1995-01-01

A hybrid combined cycle power plant including a solar central receiver for receiving solar radiation and converting it to thermal energy. The power plant includes a molten salt heat transfer medium for transferring the thermal energy to an air heater. The air heater uses the thermal energy to preheat the air from the compressor of the gas cycle. The exhaust gases from the gas cycle are directed to a steam turbine for additional energy production.

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.

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)

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

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.

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.

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

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.

Development Activities on Airbreathing Combined Cycle Engines

Science.gov (United States)

McArthur, J. Craig; Lyles, Garry (Technical Monitor)

2000-01-01

Contents include the following: Advanced reusable transportation(ART); aerojet and rocketdyne tests, RBCC focused concept flowpaths,fabricate flight weigh, test select components, document ART project, Istar (Integrated system test of an airbreathing rocket); combined cycle propulsion testbed;hydrocarbon demonstrator tracebility; Istar engine system and vehicle system closure study; and Istar project planning.

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

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

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.

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

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......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...... 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....

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

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.

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

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

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.

Exergy analysis of parabolic trough solar collectors integrated with combined steam and organic Rankine cycles

International Nuclear Information System (INIS)

Al-Sulaiman, Fahad A.

2014-01-01

Highlights: • As the solar irradiation increases, the exergetic efficiency increases. • The R134a combined cycle has best exergetic performance, 26%. • The R600a combined cycle has the lowest exergetic efficiency, 20%. • The main source of exergy destruction is the solar collector. • There is an exergetic improvement potential of 75% in the systems considered. - Abstract: In this paper, detailed exergy analysis of selected thermal power systems driven by parabolic trough solar collectors (PTSCs) is presented. The power is produced using either a steam Rankine cycle (SRC) or a combined cycle, in which the SRC is the topping cycle and an organic Rankine cycle (ORC) is the bottoming cycle. Seven refrigerants for the ORC were examined: R134a, R152a, R290, R407c, R600, R600a, and ammonia. Key exergetic parameters were examined: exergetic efficiency, exergy destruction rate, fuel depletion ratio, irreversibility ratio, and improvement potential. For all the cases considered it was revealed that as the solar irradiation increases, the exergetic efficiency increases. Among the combined cycles examined, the R134a combined cycle demonstrates the best exergetic performance with a maximum exergetic efficiency of 26% followed by the R152a combined cycle with an exergetic efficiency of 25%. Alternatively, the R600a combined cycle has the lowest exergetic efficiency, 20–21%. This study reveals that the main source of exergy destruction is the solar collector where more than 50% of inlet exergy is destructed, or in other words more than 70% of the total destructed exergy. In addition, more than 13% of the inlet exergy is destructed in the evaporator which is equivalent to around 19% of the destructed exergy. Finally, this study reveals that there is an exergetic improvement potential of 75% in the systems considered

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

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...... 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...

Theoretical analysis of a combined power and ejector refrigeration cycle using zeotropic mixture

International Nuclear Information System (INIS)

Yang, Xingyang; Zhao, Li; Li, Hailong; Yu, Zhixin

2015-01-01

Highlights: • A combined power and refrigeration cycle using zeotropic mixture is analyzed. • The cycle performances with different mixture compositions are compared. • Both exergy and parametric analysis of the combined cycle are conducted. - Abstract: A theoretical study on a combined power and ejector refrigeration cycle using zeotropic mixture isobutane/pentane is carried out. The performances of different mixture compositions are compared. An exergy analysis is conducted for the cycle. The result reveals that most exergy destruction happens in the ejector, where more than 40% exergy is lost. The heat exchange in generator causes the second largest exergy loss, larger than 28%. As the mass fraction of isobutane changes ranges from 100% to 0%, the relative exergy destruction of each component is also changing. And mixture isobutane/pentane (50/50) has the maximum exergy efficiency of 7.83%. The parametric analysis of generator temperature, condenser temperature and evaporator temperature for all the mixtures shows that, all these three thermodynamic parameters have a strong effect on the cycle performance.

Comparison of Different Technologies for Integrated Solar Combined Cycles: Analysis of Concentrating Technology and Solar Integration

Directory of Open Access Journals (Sweden)

Antonio Rovira

2018-04-01

Full Text Available This paper compares the annual performance of Integrated Solar Combined Cycles (ISCCs using different solar concentration technologies: parabolic trough collectors (PTC, linear Fresnel reflectors (LFR and central tower receiver (CT. Each solar technology (i.e. PTC, LFR and CT is proposed to integrate solar energy into the combined cycle in two different ways. The first one is based on the use of solar energy to evaporate water of the steam cycle by means of direct steam generation (DSG, increasing the steam production of the high pressure level of the steam generator. The other one is based on the use of solar energy to preheat the pressurized air at the exit of the gas turbine compressor before it is introduced in the combustion chamber, reducing the fuel consumption. Results show that ISCC with DSG increases the yearly production while solar air heating reduces it due to the incremental pressure drop. However, air heating allows significantly higher solar-to-electricity efficiencies and lower heat rates. Regarding the solar technologies, PTC provides the best thermal results.

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.

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.

New pressure control method of mixed gas in a combined cycle power plant of a steel mill

Science.gov (United States)

Xie, Yudong; Wang, Yong

2017-08-01

The enterprise production concept is changing with the development of society. A steel mill requires a combined-cycle power plant, which consists of both a gas turbine and steam turbine. It can recycle energy from the gases that are emitted from coke ovens and blast furnaces during steel production. This plant can decrease the overall energy consumption of the steel mill and reduce pollution to our living environment. To develop a combined-cycle power plant, the pressure in the mixed-gas transmission system must be controlled in the range of 2.30-2.40 MPa. The particularity of the combined-cycle power plant poses a challenge to conventional controllers. In this paper, a composite control method based on the Smith predictor and cascade control was proposed for the pressure control of the mixed gases. This method has a concise structure and can be easily implemented in actual industrial fields. The experiment has been conducted to validate the proposed control method. The experiment illustrates that the proposed method can suppress various disturbances in the gas transmission control system and sustain the pressure of the gas at the desired level, which helps to avoid abnormal shutdowns in the combined-cycle power plant.

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.

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.

Performance comparison of two low-CO2 emission solar/methanol hybrid combined cycle power systems

International Nuclear Information System (INIS)

Li, Yuanyuan; Zhang, Na; Lior, Noam

2015-01-01

Highlights: • Two novel solar hybrid combined cycle systems have been proposed and analyzed. • The power systems integrate solar-driven thermo-chemical conversion and CO 2 capture. • Exergy efficiency of about 55% and specific CO 2 emissions of 34 g/kW h are predicted. • Systems CO 2 emissions are 36.8% lower compared to a combined cycle with CO 2 capture. • The fossil fuel demand is ∼30% lower with a solar share of ∼20%. - Abstract: Two novel hybrid combined cycle power systems that use solar heat and methanol, and integrate CO 2 capture, are proposed and analyzed, one based on solar-driven methanol decomposition and the other on solar-driven methanol reforming. The high methanol conversion rates at relatively low temperatures offer the advantage of using the solar heat at only 200–300 °C to drive the syngas production by endothermic methanol conversions and its conversion to chemical energy. Pre-combustion decarbonization is employed to produce CO 2 -free fuel from the fully converted syngas, which is then burned to produce heat at the high temperature for power generation in the proposed advanced combined cycle systems. To improve efficiency, the systems’ configurations were based on the principle of cascade use of multiple heat sources of different temperatures. The thermodynamic performance of the hybrid power systems at its design point is simulated and evaluated. The results show that the hybrid systems can attain an exergy efficiency of about 55%, and specific CO 2 emissions as low as 34 g/kW h. Compared to a gas/steam combined cycle with flue gas CO 2 capture, the proposed solar-assisted system CO 2 emissions are 36.8% lower, and a fossil fuel saving ratio of ∼30% is achievable with a solar thermal share of ∼20%. The system integration predicts high efficiency conversion of solar heat and low-energy-penalty CO 2 capture, with the additional advantage that solar heat is at relatively low temperature where its collection is cheaper and

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.

Evaluation of the energy efficiency of combined cycle gas turbine. Case study of Tashkent thermal power plant, Uzbekistan

International Nuclear Information System (INIS)

Aminov, Zarif; Nakagoshi, Nobukazu; Xuan, Tran Dang; Higashi, Osamu; Alikulov, Khusniddin

2016-01-01

Highlights: • The combined cycle power plant (CCPP) has a steam turbine and a gas turbine. • Fossil fuel savings and reduction of the CCGT of was evaluated. • The performance of a three pressure CCGT is modelled under different modes. • Energy efficiency of the combined cycle was 58.28%. • An annual reduction of 1760.18 tNO_x/annum and 981.25 ktCO_2/annum can be achieved. - Abstract: The power generation of Tashkent Thermal Power Plant (TPP) is based on conventional power units. Moreover, the facility suffers from limited efficiency in electricity generation. The plant was constructed during the Soviet era. Furthermore, the power plant is being used for inter-hour power generation regulation. As a result, the efficiency can be reduced by increasing specific fuel consumption. This research focuses on the evaluation of the energy efficiency of the combined cycle gas turbine (CCGT) for the Tashkent TPP. Specifically, the objective is an evaluation of fossil fuel savings and reduction of CO_2 and NO_x emissions with the using CCGT technology at conventional power plant. The proposed combined cycle power plant (CCPP) includes an existing steam turbine (ST) with 160 MW capacity, heat recovery steam generator (HRSG), and gas turbine (GT) technology with 300 MW capacity. The performance of a three pressure CCGT is modelled under different modes. As a result, the efficiency of the combined cycle was evaluated at 58.28%, while the conventional cycle had an efficiency of 34.5%. We can achieve an annual reduction of 1760.18 tNO_x/annum and 981.25 ktCO_2/annum.

Novel combined cycle configurations for propane pre-cooled mixed refrigerant (APCI) natural gas liquefaction cycle

International Nuclear Information System (INIS)

Mortazavi, Amir; Alabdulkarem, Abdullah; Hwang, Yunho; Radermacher, Reinhard

2014-01-01

Highlights: • 10 New LNG plants driver cycle enhancement configurations were developed. • All the 14 enhancement options design variables were optimized to demonstrate their energy saving potentials. • The best driver cycle enhancement option improved the driver cycle energy efficiency by 38%. • The effects of technological advancements on the performances of the enhancement options were studied. - Abstract: A significant amount of energy is required for natural gas liquefaction. Due to the production scale of LNG plants, they consume an intensive amount of energy. Consequently, any enhancement to the energy efficiency of LNG plants will result in a considerable reduction in natural gas consumption and CO 2 emission. Compressor drivers are the main energy consumer in the LNG plants. In this paper, 14 different driver cycle enhancement options were considered. A number of these options have not been proposed for the LNG plants. The new driver cycle development was performed by analyzing and optimizing the design variables of four conventional driver cycle enhancement options. The optimization results were used to develop more efficient cycles through mitigating the active constrains and driver cycle innovations. Based on the current available technologies five of our newly developed driver cycle configurations have higher efficiency than the most efficient existing conventional driver cycle. The best developed driver cycle enhancement option improved the base driver cycle energy efficiency by 38%. The effects of technological advancement on the performances of the all driver cycle enhancement options were also considered

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.

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.

Exergy analysis for combined regenerative Brayton and inverse Brayton cycles

OpenAIRE

Zelong Zhang, Lingen Chen, Fengrui Sun

2012-01-01

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 efficien...

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.

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.

Performance analysis of solar parabolic trough collectors driven combined supercritical CO2 and organic Rankine cycle

Directory of Open Access Journals (Sweden)

Harwinder Singh

2018-06-01

Full Text Available In this paper, attempts have been made on the detailed energy and exergy analysis of solar parabolic trough collectors (SPTCs driven combined power plant. The combination of supercritical CO2 (SCO2 cycle and organic Rankine cycle (ORC integrated with SPTCs has been used to produce power, in which SCO2 cycle and ORC are arranged as a topping and bottoming cycle. Five organic working fluids like R134a, R1234yf, R407c, R1234ze, and R245fa were selected for a low temperature bottoming ORC. Five key exergetic parameters such as exergetic efficiency, exergy destruction rate, fuel depletion ratio, irreversibility ratio, and improvement potential were also examined. It was revealed that exergetic and thermal efficiency of all the combined cycles enhances as the direct normal irradiance increases from 0.5 kW/m2 to 0.95 kW/m2. As can be seen, R407c combined cycle has the maximum exergetic as well as thermal efficiency which is around 78.07% at 0.95 kW/m2 and 43.49% at 0.95 kW/m2, respectively. Alternatively, the R134a and R245fa combined cycle yields less promising results with the marginal difference in their performance. As inferred from the study that SCO2 turbine and evaporator has a certain amount of exergy destruction which is around 9.72% and 8.54% of the inlet exergy, and almost 38.10% of the total exergy destruction in case of R407c combined cycle. Moreover, the maximum amount of exergy destructed by the solar collector field which is more than 25% of the solar inlet exergy and around 54% of the total destructed exergy. Finally, this study concludes that R407c combined cycle has a minimum fuel depletion ratio of 0.2583 for a solar collector and possess the highest power output of 3740 kW. Keywords: Supercritical CO2cycle, Organic Rankine cycle, Exergetic performance, SPTCs, Organic fluids

Power conversion systems based on Brayton cycles for fusion reactors

International Nuclear Information System (INIS)

Linares, J.I.; Herranz, L.E.; Moratilla, B.Y.; Serrano, I.P.

2011-01-01

This paper investigates Brayton power cycles for fusion reactors. Two working fluids have been explored: helium in classical configurations and CO 2 in recompression layouts (Feher cycle). Typical recuperator arrangements in both cycles have been strongly constrained by low temperature of some of the energy thermal sources from the reactor. This limitation has been overcome in two ways: with a combined architecture and with dual cycles. Combined architecture couples the Brayton cycle with a Rankine one capable of taking advantage of the thermal energy content of the working fluid after exiting the turbine stage (iso-butane and steam fitted best the conditions of the He and CO 2 cycles, respectively). Dual cycles set a specific Rankine cycle to exploit the lowest quality thermal energy source, allowing usual recuperator arrangements in the Brayton cycle. The results of the analyses indicate that dual cycles could reach thermal efficiencies around 42.8% when using helium, whereas thermal performance might be even better (46.7%), if a combined CO 2 -H 2 O cycle was set.

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.

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.

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

Low CO2-emissions hybrid solar combined-cycle power system with methane membrane reforming

International Nuclear Information System (INIS)

Li, Yuanyuan; Zhang, Na; Cai, Ruixian

2013-01-01

Based on the principle of cascade utilization of multiple energy resources, a gas-steam combined cycle power system integrated with solar thermo-chemical fuel conversion and CO 2 capture has been proposed and analyzed. The collected solar heat at 550 °C drives the endothermic methane reforming and is converted to the produced syngas chemical exergy, and then released as high-temperature thermal energy via combustion for power generation, achieving its high-efficiency heat-power conversion. The reforming reaction is integrated with a hydrogen separation membrane, which continuously withdraws hydrogen from the reaction zone and enables nearly full methane conversion. The CO 2 enriched gas being concentrated in the retentate zone is collected and processed with pre-combustion decarbonization. The system is thermodynamically simulated using the ASPEN PLUS code. The results show that with 91% CO 2 captured, the specific CO 2 emission is 25 g/kWh. An exergy efficiency of 58% and thermal efficiency of 51.6% can be obtained. A fossil fuel saving ratio of 31.2% is achievable with a solar thermal share of 28.2%, and the net solar-to-electricity efficiency based on the gross solar heat incident on the collector is about 36.4% compared with the same gas-steam combined cycle system with an equal CO 2 removal ratio obtained by post-combustion decarbonization. - Highlights: ► A solar-assisted hybrid combined cycle power system has been proposed and analyzed. ► The system integrates power generation with solar-driven reforming and CO 2 capture. ► solar heat upgrading and high-efficiency heat-to-power conversion are achieved. ► membrane reforming enables high CH 4 conversion and pre-combustion CO 2 capture. ► The system thermodynamic performances have been investigated and compared

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

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%.

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)

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)

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.

Combination of IVF and IVM in naturally cycling women

DEFF Research Database (Denmark)

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

2012-01-01

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...... and pregnancy/live births compared with conventional unstimulated IVF treatment and at the same time eliminate the risk of ovarian hyperstimulation syndrome. This prospective trial included 77 women with regular menstrual cycles. Age at inclusion was between 20 and 37 years. Results showed a retrieval rate...... between endometrial factors and IVM oocytes together with unknown competence of IVM embryos is suspected. For some time, there has been an increasing interest in mild approaches for fertility treatment, in particular IVF. In-vitro maturation (IVM) of immature eggs outside the ovaries followed by IVF...

Techno-economic process design of a commercial-scale amine-based CO_2 capture system for natural gas combined cycle power plant with exhaust gas recirculation

International Nuclear Information System (INIS)

Ali, Usman; Agbonghae, Elvis O.; Hughes, Kevin J.; Ingham, Derek B.; Ma, Lin; Pourkashanian, Mohamed

2016-01-01

Highlights: • EGR is a way to enhance the CO_2 content with reduction in design variables and cost. • Both process and economic analyses are essential to reach the optimum design variables. • Commercial-scale NGCC with and without EGR is presented. • Process design of the amine-based CO_2 capture plant is evaluated for with and without EGR. - Abstract: Post-combustion CO_2 capture systems are gaining more importance as a means of reducing escalating greenhouse gas emissions. Moreover, for natural gas-fired power generation systems, exhaust gas recirculation is a method of enhancing the CO_2 concentration in the lean flue gas. The present study reports the design and scale-up of four different cases of an amine-based CO_2 capture system at 90% capture rate with 30 wt.% aqueous solution of MEA. The design results are reported for a natural gas-fired combined cycle system with a gross power output of 650 MW_e without EGR and with EGR at 20%, 35% and 50% EGR percentage. A combined process and economic analysis is implemented to identify the optimum designs for the different amine-based CO_2 capture plants. For an amine-based CO_2 capture plant with a natural gas-fired combined cycle without EGR, an optimum liquid to gas ratio of 0.96 is estimated. Incorporating EGR at 20%, 35% and 50%, results in optimum liquid to gas ratios of 1.22, 1.46 and 1.90, respectively. These results suggest that a natural gas-fired power plant with exhaust gas recirculation will result in lower penalties in terms of the energy consumption and costs incurred on the amine-based CO_2 capture plant.

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.

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

Combined cycle power plants: technological prospects for improving the efficiency

International Nuclear Information System (INIS)

Lauri, R.

2009-01-01

The combined cycle power plants characteristics are better than one course open to a closed loop presenting an electrical efficiency close to 60% do not reach for gas turbine engines for power plants and conventional steam engines. [it

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

Cycle-by-cycle variations in a spark ignition engine fueled with natural gas-hydrogen blends combined with EGR

Energy Technology Data Exchange (ETDEWEB)

Huang, Bin; Hu, Erjiang; Huang, Zuohua; Zheng, Jianjun; Liu, Bing; Jiang, Deming [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, 710049 Xi' an (China)

2009-10-15

Study of cycle-by-cycle variations in a spark ignition engine fueled with natural gas-hydrogen blends combined with exhaust gas recirculation (EGR) was conducted. The effects of EGR ratio and hydrogen fraction on engine cycle-by-cycle variations are analyzed. The results show that the cylinder peak pressure, the maximum rate of pressure rise and the indicated mean effective pressure decrease and cycle-by-cycle variations increase with the increase of EGR ratio. Interdependency between the above parameters and their corresponding crank angles of cylinder peak pressure is decreased with the increase of EGR ratio. For a given EGR ratio, combustion stability is promoted and cycle-by-cycle variations are decreased with the increase of hydrogen fraction in the fuel blends. Non-linear relationship is presented between the indicated mean effective pressure and EGR ratio. Slight influence of EGR ratio on indicated mean effective pressure is observed at low EGR ratios while large influence of EGR ratio on indicated mean effective pressure is demonstrated at high EGR ratios. The high test engine speed has lower cycle-by-cycle variations due to the enhancement of air flow turbulence and swirls in the cylinder. Increasing hydrogen fraction can maintain low cycle-by-cycle variations at high EGR ratios. (author)

Are combined cycle plants being driven to zero discharge?

International Nuclear Information System (INIS)

Sinha, P.K.; Narula, R.G.; Weidinger, G.F.

1991-01-01

This paper discusses the water-related environmental issues of siting combined cycle plants, including availability of plant makeup water and wastewater discharge. The need for water treatment equipment for waste minimization, recycle, and/or zero discharge is discussed. The key water-related permit issues and preliminary design commitments are demonstrated via case histories

Ongoing Analyses of Rocket Based Combined Cycle Engines by the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center

Science.gov (United States)

Ruf, Joseph H.; Holt, James B.; Canabal, Francisco

2001-01-01

This paper presents the status of analyses on three Rocket Based Combined Cycle (RBCC) configurations underway in the Applied Fluid Dynamics Analysis Group (TD64). TD64 is performing computational fluid dynamics (CFD) analysis on a Penn State RBCC test rig, the proposed Draco axisymmetric RBCC engine and the Trailblazer engine. The intent of the analysis on the Penn State test rig is to benchmark the Finite Difference Navier Stokes (FDNS) code for ejector mode fluid dynamics. The Draco analysis was a trade study to determine the ejector mode performance as a function of three engine design variables. The Trailblazer analysis is to evaluate the nozzle performance in scramjet mode. Results to date of each analysis are presented.

Ongoing Analysis of Rocket Based Combined Cycle Engines by the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center

Science.gov (United States)

Ruf, Joseph; Holt, James B.; Canabal, Francisco

1999-01-01

This paper presents the status of analyses on three Rocket Based Combined Cycle configurations underway in the Applied Fluid Dynamics Analysis Group (TD64). TD64 is performing computational fluid dynamics analysis on a Penn State RBCC test rig, the proposed Draco axisymmetric RBCC engine and the Trailblazer engine. The intent of the analysis on the Penn State test rig is to benchmark the Finite Difference Navier Stokes code for ejector mode fluid dynamics. The Draco engine analysis is a trade study to determine the ejector mode performance as a function of three engine design variables. The Trailblazer analysis is to evaluate the nozzle performance in scramjet mode. Results to date of each analysis are presented.

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.

The effective use of gas turbines and combined cycle technology in heat and electrical energy production

International Nuclear Information System (INIS)

Boehm, B.; Stark, E.

1999-01-01

The modernization of the energy industry in many countries is a real challenge for both, the policy makers as well as for the power industry. Especially, the efficient satisfaction of the heat and electrical demand of big cities will remain an interesting task for supply companies and hence for today engineers and economists, because the availability of natural gas from Russia and from other deposits owning countries for the decades to come, cogeneration by using modern gas turbines and combined cycle technologies is a key and corner stone of supply, not the least for its very low emission and small environmental loading. It is the intention of this paper, to demonstrate under resource to: 1) the high potential of natural gas-based cogeneration; 2) the high efficiency of gas turbines and combined cycle plants; 3) their flexibility to cover different demands; 4) the operational experience with gas turbines and combined cycle cogeneration plants; 5) the very good environmental behavior of gas turbines. Actually, the highest utilization of primary energy resources is afforded with natural gas and described technology. Future gradual rise of gas prices can bring about a shift from the present main application in high efficiency load plants to mid range load operation of cogeneration plants. (Author)

Combined cycle plant controls retrofit case history

International Nuclear Information System (INIS)

Tenney, D.; Pieszchala, T.

1991-01-01

The Comanche Power Station, Public Service of Oklahoma's combined cycle generating facility, underwent a controls and operator panel retrofit at the end of 1988. The plant consists of two gas turbines, two heat recovery boilers and a steam turbine along with three generators. This paper examines the extent to which the original goals and specifications were met. Costs, operating principles and modifications since the original installation are discussed. Operating procedures are compared with the original system. The future of the plant is discussed and the impact on the power system grid is analyzed

Predominantly elastic crack growth under combined creep-fatigue cycling

International Nuclear Information System (INIS)

Lloyd, G.J.

1979-01-01

A rationalization of the various observed effects of combined creep-fatigue cycling upon predominantly elastic fatigue-crack propagation in austenitic steel is presented. Existing and new evidence is used to show two main groups of behaviour: (i) material and cycling conditions which lead to modest increases (6-8 times) in the rate of crack growth are associated with relaxation-induced changes in the material deformation characteristics, and (ii) material and cycling conditions severe enough to generate internal fracture damage lead to significant (up to a factor of 30) increases in crack growth rate when compared with fast-cycling crack propagation rates at the same temperature. A working hypothesis is presented to show that the boundary between the two groups occurs when the scale of the nucleated creep damage is of the same magnitude as the crack tip opening displacement. This leads to the possibility of unstable crack advance. Creep crack growth rates are shown to provide an upper bound to creep-fatigue crack growth rates when crack advance is unstable. If the deformation properties only are affected by the creep-fatigue cycling then creep crack growth rates provide a lower bound. The role of intergranular oxygen corrosion in very low frequency crack growth tests is also briefly discussed. (author)

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

Thermal cycle efficiency of the indirect combined HTGR-GT power generation system

Energy Technology Data Exchange (ETDEWEB)

Muto, Yasushi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1996-02-01

High thermal efficiency of 50% could be expected in a power generation system coupling a high temperature gas-cooled reactor(HTGR) with a closed cycle gas turbine(GT). There are three candidate systems such as a direct cycle(DC), an indirect cycle(ICD) and an indirect combined cycle(IDCC). The IDCC could solve many problems in both the DC and the IDC and consists of a primary circuit and a secondary circuit where a topping cycle is a Brayton cycle and a bottoming cycle is a steam cycle. In this report, the thermal cycle efficiency of the IDCC is examined regarding configurations of components and steam pressure. It has been shown that there are two types of configurations, that is, a perfect cascade type and a semi-cascade one and the latter can be further classified into Case A, Case B and Case C. The conditions achieving the maximum thermal cycle efficiency were revealed for these cases. In addition, the optimum system configurations were proposed considering the thermal cycle efficiency, safety and plant arrangement. (author).

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

Science.gov (United States)

Moghimi, Mahdi; Khosravian, Mohammadreza

2018-06-01

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.

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.

Exergetic and economic evaluation of the effect of HRSG configurations on the performance of combined cycle power plants

International Nuclear Information System (INIS)

Tajik Mansouri, Mohammad; Ahmadi, Pouria; Ganjeh Kaviri, Abdolsaeid; Jaafar, Mohammad Nazri Mohd

2012-01-01

Highlights: ►To conduct the comprehensive exergy and economic analysis for advanced combined cycle power plant. ►To study three different HRSG configurations, dual and triple pressure HRSG, based on thermodynamic relations. ►To have a better performance assessment of the system studied using exergy and economic criteria. - Abstract: In the present research study, the effect of HRSG pressure levels on exergy efficiency of combined cycle power plants is investigated. Hence, three types of gas turbine combined cycles, with the same gas turbine as a topping cycle are evaluated. A double pressure, and two triple pressure HRSGs (with and without reheat) are modeled. The results show how an increase in the number of pressure levels of the HRSG affect the exergy losses due to heat transfer in the HRSG and the exhaust of flue gas to the stack. Moreover, the results show that an increase in the number of pressure levels affects the exergy destruction rate in HRSG, and as a result, it causes a tangible increase in exergy efficiency of the whole cycle. The results from thermodynamic analysis show that the losses due to heat transfer in the HRSG and the exhaust of flue gas to the stack in a triple pressure reheat combined cycle are less than the other cases. From the economic analysis, it is found that increasing the number of pressure levels of steam generation leads to an increase for the total and specific investment cost of the plant for about 6% and 4% respectively. The net present value (NPV) of the plant increases for about 7% for triple pressure reheat compared to with the double pressure CCPP. Therefore, the results of economic analysis show that it is economically justifiable to increase the number of pressure levels of steam generation in HRSG.

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.

Proposing a novel combined cycle for optimal exergy recovery of liquefied natural gas

Energy Technology Data Exchange (ETDEWEB)

Salimpour, M.R.; Zahedi, M.A. [Isfahan University of Technology (Iran, Islamic Republic of). Department of Mechanical Engineering

2012-08-15

The effective utilization of the cryogenic exergy associated with liquefied natural gas (LNG) vaporization is important. In this paper, a novel combined power cycle is proposed which utilizes LNG in different ways to enhance the power generation of a power plant. In addition to the direct expansion in the appropriate expander, LNG is used as a low-temperature heat sink for a middle-pressure gas cycle which uses nitrogen as working fluid. Also, LNG is used to cool the inlet air of an open Brayton gas turbine cycle. These measures are accomplished to improve the exergy recovery of LNG. In order to analyze the performance of the system, the influence of several key parameters such as pressure ratio of LNG turbine, ratio of the mass flow rate of LNG to the mass flow rate of air, pressure ratio of different compressors, LNG pressure and inlet pressure of nitrogen compressor, on the thermal efficiency and exergy efficiency of the offered cycle is investigated. Finally, the proposed combined cycle is optimized on the basis of first and second laws of thermodynamics. (orig.)

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.

Dynamic simulation of combined cycle power plant cycling in the electricity market

International Nuclear Information System (INIS)

Benato, A.; Bracco, S.; Stoppato, A.; Mirandola, A.

2016-01-01

Highlights: • The flexibility of traditional power plants have become of primary importance. • Three dynamic models of the same single pressure HRSG are built. • The plant dynamic behaviour is predicted. • A lifetime calculation procedure is proposed and tested. • The drum lifetime reduction is estimated. - Abstract: The energy markets deregulation coupled with the rapid spread of unpredictable energy sources power units are stressing the necessity of improving traditional power plants flexibility. Cyclic operation guarantees high profits in the short term but, in the medium-long time, cause a lifetime reduction due to thermo-mechanical fatigue, creep and corrosion. In this context, Combined Cycle Power Plants are the most concerned in flexible operation problems. For this reason, two research groups from two Italian universities have developed a procedure to estimate the devices lifetime reduction with a particular focus on steam drums and superheaters/reheaters. To assess the lifetime reduction, it is essential to predict the thermodynamic variables trend in order to describe the plant behaviour. Therefore, the core of the procedure is the power plant dynamic model. At this purpose, in this paper, three different dynamic models of the same single pressure Combined Cycle Gas Turbine are presented. The models have been built using three different approaches and are used to simulate plant behaviour under real operating conditions. Despite these differences, the thermodynamic parameters time profiles are in good accordance as presented in the paper. At last, an evaluation of the drum lifetime reduction is performed.

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.

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

Science.gov (United States)

Marinangeli, Christopher P. F.; Tremorin, Denis

2018-01-01

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. PMID:29659497

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.

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.

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…

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.

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

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

. 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...

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.

Exergy analysis and optimisation of a marine molten carbonate fuel cell system in simple and combined cycle configuration

International Nuclear Information System (INIS)

Dimopoulos, George G.; Stefanatos, Iason C.; Kakalis, Nikolaos M.P.

2016-01-01

Highlights: • Process modelling and optimisation of an integrated marine MCFC system. • Component-level and spatially distributed exergy analysis and balances. • Optimal simple cycle MCFC system with 45.5% overall exergy efficiency. • Optimal combined cycle MCFC system with 60% overall exergy efficiency. • Combined cycle MCFC system yields 30% CO_2 relative emissions reduction. - Abstract: In this paper we present the exergy analysis and design optimisation of an integrated molten carbonate fuel cell (MCFC) system for marine applications, considering waste heat recovery options for additional power production. High temperature fuel cells are attractive solutions for marine energy systems, as they can significantly reduce gaseous emissions, increase efficiency and facilitate the introduction of more environmentally-friendly fuels, like LNG and biofuels. We consider an already installed MCFC system onboard a sea-going vessel, which has many tightly integrated sub-systems and components: fuel delivery and pre-reforming, internal reforming sections, electrochemical conversion, catalytic burner, air supply and high temperature exhaust gas. The high temperature exhaust gasses offer significant potential for heat recovery that can be directed into both covering the system’s auxiliary heat requirements and power production. Therefore, an integrated systems approach is employed to accurately identify the true sources of losses in the various components and to optimise the overall system with respect to its energy efficiency, taking into account the various trade-offs and subject to several constraints. Here, we present a four-step approach: a. dynamic process models development of simple and combined-cycle MCFC system; b. MCFC components and system models calibration via onboard MCFC measurements; c. exergy analysis, and d. optimisation of the simple and combined-cycle systems with respect to their exergetic performance. Our methodology is based on the

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

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

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.

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

Energy Technology Data Exchange (ETDEWEB)

Brunet, Robert; Cortes, Daniel [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Campus Sescelades, Avinguda Paisos Catalans 26, 43007 Tarragona (Spain); Guillen-Gosalbez, Gonzalo [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Campus Sescelades, Avinguda Paisos Catalans 26, 43007 Tarragona (Spain); Jimenez, Laureano [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Campus Sescelades, Avinguda Paisos Catalans 26, 43007 Tarragona (Spain); Boer, Dieter [Departament d' Enginyeria Mecanica, Escola Tecnica Superior d' Enginyeria, Universitat Rovira i Virgili, Campus Sescelades, Avinguda Paisos Catalans 26, 43007, Tarragona (Spain)

2012-12-15

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: Black-Right-Pointing-Pointer Novel framework for the optimal design of thermdoynamic cycles. Black-Right-Pointing-Pointer Combined use of simulation and optimization tools. Black-Right-Pointing-Pointer Optimal design and operating conditions according to several economic and LCA impacts. Black-Right-Pointing-Pointer Design of a 10MW Rankine cycle in Aspen Hysys, and a 90kW absorption cycle in Aspen Plus.

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)

An update technology for integrated biomass gasification combined cycle power plant

International Nuclear Information System (INIS)

Bhattacharya, P.; Dey, S.

2014-01-01

A discussion is presented on the technical analysis of a 6.4 M W_e integrated biomass gasification combined cycle (IBGCC) plant. It features three numbers of downdraft biomass gasifier systems with suitable gas clean-up trains, three numbers of internal combustion (IC) producer gas engines for producing 5.85 MW electrical power in open cycle and 550 kW power in a bottoming cycle using waste heat. Comparing with IC gas engine single cycle systems, this technology route increases overall system efficiency of the power plant, which in turn improves plant economics. Estimated generation cost of electricity indicates that mega-watt scale IBGCC power plants can contribute to good economies of scale in India. This paper also highlight's the possibility of activated carbon generation from the char, a byproduct of gasification process, and use of engine's jacket water heat to generate chilled water through VAM for gas conditioning. (author)

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.

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

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

Performance evaluation of combined ejector LiBr/H2O absorption cooling cycle

Directory of Open Access Journals (Sweden)

Hasan Sh. Majdi

2016-03-01

Full Text Available The objective of this work is to develop a computer simulation program to evaluate the performance of solar-assited combined ejector absorption (single-effect cooling system using LiBr/H2O as a working fluid and operating under steady-state conditions. The ejector possess no moving parts and is simple and reliable, which makes it attractive for combination with single-stage absorption cycle for further improvement to the system's performance. In this research, improvement to the system is achieved by utilizing the potential kinetic energy of the ejector to enhance refrigeration efficiency. The effects of the entrainment ratio of the ejector, operating temperature, on the thermal loads, and system performance have been investigated. The results showed that the evaporator and condenser loads, post-addition of the ejector, is found to be permanently higher than that in the basic cycle, which indicates a significant enhancement of the proposed cycle and the cooling capacity of the system increasing with the increase in evaporator temperature and entrainment ratio. The COP of the modified cycle is improved by up to 60 % compared with that of the basic cycle at the given condition. This process stabilizes the refrigeration system, enhanced its function, and enabled the system to work under higher condenser temperatures.

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

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...... 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...

Application of a personal computer relational data base management system to fuel cycle economic scoping

International Nuclear Information System (INIS)

Malone, J.P.; Dooley, G.D.

1986-01-01

A personal computer (PC) relational data base management system (RDBMS) permits large quantities of data to be maintained in a data base composed of structured data sets or files and provides data access through a software environment, procedure, or program language. The features of an RDBMS-based system create an environment on a PC that can provide significant benefits to any fuel cycle economics analysis. The ability to maintain a separate data set for each fuel cycle parameter group and the ability to manipulate the data through a series of independent calculation modules combine to provide the fuel cycle analyst with more time to examine and use the data, because less time is required to manipulate it

Large eddy simulation of combustion characteristics in a kerosene fueled rocket-based combined-cycle engine combustor

Science.gov (United States)

Huang, Zhi-wei; He, Guo-qiang; Qin, Fei; Cao, Dong-gang; Wei, Xiang-geng; Shi, Lei

2016-10-01

This study reports combustion characteristics of a rocket-based combined-cycle engine combustor operating at ramjet mode numerically. Compressible large eddy simulation with liquid kerosene sprayed and vaporized is used to study the intrinsic unsteadiness of combustion in such a propulsion system. Results for the pressure oscillation amplitude and frequency in the combustor as well as the wall pressure distribution along the flow-path, are validated using experimental data, and they show acceptable agreement. Coupled with reduced chemical kinetics of kerosene, results are compared with the simultaneously obtained Reynolds-Averaged Navier-Stokes results, and show significant differences. A flow field analysis is also carried out for further study of the turbulent flame structures. Mixture fraction is used to determine the most probable flame location in the combustor at stoichiometric condition. Spatial distributions of the Takeno flame index, scalar dissipation rate, and heat release rate reveal that different combustion modes, such as premixed and non-premixed modes, coexisted at different sections of the combustor. The RBCC combustor is divided into different regions characterized by their non-uniform features. Flame stabilization mechanism, i.e., flame propagation or fuel auto-ignition, and their relative importance, is also determined at different regions in the combustor.

Modeling and simulation of syngas purification and power generation in integrated gasification combined cycle (IGCS)

Energy Technology Data Exchange (ETDEWEB)

Mehmood, N; Zaman, Z U; Mehran, M T [National Development, Islamabad (Pakistan)

2011-07-01

Integrated Gasification Combined Cycle (IGCC) is one of the most promising technologies for power generation; The environmental benefits and the higher energy conversion efficiency distinguish it from traditional coal generation technologies. This work presents a structured and validated conceptual model of purification of coal gas produced during the Underground Coal Gasification (UCG) of coal containing high sulfur contents. Gas cleaning operations for CO/sub 2/, H/sub 2/S and moisture removal have been modeled in steady and dynamic state. The power generation from combined cycle is also modeled. The model has been developed using Aspen HYSYS and Aspen Plus simulation software. Predicted results of clean gas composition and generated power present a good agreement with industrial data and efficiency parameters. This study is aimed at obtaining optimal assessment of an integrated gasification combined cycle (IGCC) power plant configurations. (author)

Modeling and simulation of syngas purification and power generation in integrated gasification combined cycle (IGCS)

International Nuclear Information System (INIS)

Mehmood, N.; Zaman, Z.U.; Mehran, M.T.

2011-01-01

Integrated Gasification Combined Cycle (IGCC) is one of the most promising technologies for power generation; The environmental benefits and the higher energy conversion efficiency distinguish it from traditional coal generation technologies. This work presents a structured and validated conceptual model of purification of coal gas produced during the Underground Coal Gasification (UCG) of coal containing high sulfur contents. Gas cleaning operations for CO/sub 2/, H/sub 2/S and moisture removal have been modeled in steady and dynamic state. The power generation from combined cycle is also modeled. The model has been developed using Aspen HYSYS and Aspen Plus simulation software. Predicted results of clean gas composition and generated power present a good agreement with industrial data and efficiency parameters. This study is aimed at obtaining optimal assessment of an integrated gasification combined cycle (IGCC) power plant configurations. (author)

Economic comparison of clean coal generating technologies with natural gas-combined cycle systems

International Nuclear Information System (INIS)

Sebesta, J.J.; Hoskins, W.W.

1990-01-01

This paper reports that there are four combustion technologies upon which U.S. electric utilities are expected to rely for the majority of their future power generating needs. These technologies are pulverized coal- fired combustion (PC); coal-fired fluidized bed combustion (AFBC); coal gasification, combined cycle systems (CGCC); and natural gas-fired combined cycle systems (NGCC). The engineering and economic parameters which affect the choice of a technology include capital costs, operating and maintenance costs, fuel costs, construction schedule, process risk, environmental and site impacts, fuel efficiency and flexibility, plant availability, capacity factors, timing of startup, and the importance of utility economic and financial factors

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

Pressurized fluidized bed combustion combined cycle power plant with coal gasification: Second generation pilot plant

International Nuclear Information System (INIS)

Farina, G.L.; Bressan, L.

1991-01-01

This paper presents the technical and economical background of a research and development program of a novel power generation scheme, which is based on coal gasification, pressurized fluid bed combustion and combined cycles. The participants in this program are: Foster Wheeler (project leader), Westinghouse, IGT and the USA Dept. of Energy. The paper describes the characteristics of the plant, the research program in course of implementation, the components of the pilot plant and the first results obtained

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

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

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.

Conventional and advanced exergetic analyses applied to a combined cycle power plant

International Nuclear Information System (INIS)

Petrakopoulou, Fontina; Tsatsaronis, George; Morosuk, Tatiana; Carassai, Anna

2012-01-01

Conventional exergy-based methods pinpoint components and processes with high irreversibilities. However, they lack certain insight. For a given advanced technological state, there is a minimum level of exergy destruction related to technological and/or economic constraints that is unavoidable. Furthermore, in any thermodynamic system, exergy destruction stems from both component interactions (exogenous) and component inefficiencies (endogenous). To overcome the limitations of the conventional analyses and to increase our knowledge about a plant, advanced exergy-based analyses have been developed. In this paper, a combined cycle power plant is analyzed using both conventional and advanced exergetic analyses. Except for the expander of the gas turbine system and the high-pressure steam turbine, most of the exergy destruction in the plant components is unavoidable. This unavoidable part is constrained by internal technological limitations, i.e. each component’s endogenous exergy destruction. High levels of endogenous exergy destruction show that component interactions do not contribute significantly to the thermodynamic inefficiencies. In addition, these inefficiencies are unavoidable to a large extent. With the advanced analysis, new improvement strategies are revealed that could not otherwise be found. -- Highlights: ► This is the first application of a complete advanced exergetic analysis to a complex power plant. ► In the three-pressure-level combined cycle power plant studied here, the improvement potential of the majority of the components is low, since most of the exergy destruction is unavoidable. ► Component interactions are generally of lower importance for the considered plant. ► Splitting the exogenous exergy destruction reveals one-to-one component interactions and improvement strategies. ► The advanced exergetic analysis is a necessary supplement to the conventional analysis in improving a complex system.

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.

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.

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

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

Increasing thermal efficiency of Rankine cycles by using refrigeration cycles: A theoretical analysis

International Nuclear Information System (INIS)

Sarr, Joachim-André Raymond; Mathieu-Potvin, François

2016-01-01

Highlights: • A new stratagem is proposed to improve thermal efficiency of Rankine cycles. • Three new configurations are optimized by means of numerical simulations. • The Rankine-1SCR design is advantageous for 1338 different fluid combinations. • The Rankine-2SCR design is advantageous for 772 different fluid combinations. • The Rankine-3SCR design is advantageous for 768 different fluid combinations. - Abstract: In this paper, three different modifications of the basic Rankine thermodynamic cycle are proposed. The objective is to increase the thermal efficiency of power systems based on Rankine cycles. The three new systems are named “Rankine-1SCR”, “Rankine-2SCR”, and “Rankine-3SCR” cycles, and they consist of linking a refrigeration cycle to the basic Rankine cycle. The idea is to use the refrigeration cycle to create a low temperature heat sink for the Rankine cycle. These three new power plant configurations are modeled and optimized with numerical tools, and then they are compared with the basic Rankine cycle. The objective function is the thermal efficiency of the systems (i.e., net power output (kW) divided by heat rate (kW) entering the system), and the design variables are the operating temperatures within the systems. Among the 84 × 84 (i.e., 7056) possible combinations of working and cooling fluids investigated in this paper, it is shown that: (i) the Rankine-1SCR system is advantageous for 1338 different fluid combinations, (ii) the Rankine-2SCR system is advantageous for 772 different fluid combinations, and (iii) the Rankine-3SCR system is advantageous for 768 different fluid combinations.

Integrated gasification combined cycle for acid rain control

Energy Technology Data Exchange (ETDEWEB)

Simbeck, D.R.; Dickenson, R.L.

1986-10-01

The role of integrated coal gasification combined-cycle power plants in the abatement of emission of SO/sub 2/ and NO/sub 2/ which lead to acid rain is discussed. The economics of this IGCC approach are assessed for a nominal 500 MW plant size. Phased construction of IGCC plants is recommended as a means of reducing SO/sub 2/ and NO/sub x/ emissions noting that high-sulfur coals could continue to be used. It is also noted that phased construction IGCC is the only acid rain control technology that greatly reduces NO/sub x/. 17 references.

Integrated operation and management system for a 700MW combined cycle power plant

Energy Technology Data Exchange (ETDEWEB)

Shiroumaru, I. (Yanai Power Plant Construction Office, Chugoku Electric Power Co., Inc., 1575-5 Yanai-Miyamoto-Shiohama, Yanai-shi, Yamaguchi-ken (JP)); Iwamiya, T. (Omika Works, Hitachi, Ltd., 5-2-1 Omika-cho, Hitachi-shi, Ibaraki-ken (JP)); Fukai, M. (Hitachi Works, Hitachi, Ltd., 3-1-1 Saiwai-cho, Hitachi-shi, Ibaraki-ken (JP))

1992-03-01

Yanai Power Plant of the Chugoku Electric Power Co., Inc. (Yamaguchi Pref., Japan) is in the process of constructing a 1400MW state-of-the-art combined cycle power plant. The first phase, a 350MW power plant, started operation on a commercial basis in November, 1990. This power plant has achieved high efficiency and high operability, major features of a combined cycle power plant. The integrated operation and management system of the power plant takes care of operation, maintenance, control of general business, etc., and was built using the latest computer and digital control and communication technologies. This paper reports that it is expected that this system will enhance efficient operation and management for the power plant.

Off-design performance of a chemical looping combustion (CLC) combined cycle: effects of ambient temperature

Science.gov (United States)

Chi, Jinling; Wang, Bo; Zhang, Shijie; Xiao, Yunhan

2010-02-01

The present work investigates the influence of ambient temperature on the steady-state off-design thermodynamic performance of a chemical looping combustion (CLC) combined cycle. A sensitivity analysis of the CLC reactor system was conducted, which shows that the parameters that influence the temperatures of the CLC reactors most are the flow rate and temperature of air entering the air reactor. For the ambient temperature variation, three off-design control strategies have been assumed and compared: 1) without any Inlet Guide Vane (IGV) control, 2) IGV control to maintain air reactor temperature and 3) IGV control to maintain constant fuel reactor temperature, aside from fuel flow rate adjusting. Results indicate that, compared with the conventional combined cycle, due to the requirement of pressure balance at outlet of the two CLC reactors, CLC combined cycle shows completely different off-design thermodynamic characteristics regardless of the control strategy adopted. For the first control strategy, temperatures of the two CLC reactors both rise obviously as ambient temperature increases. IGV control adopted by the second and the third strategy has the effect to maintain one of the two reactors' temperatures at design condition when ambient temperature is above design point. Compare with the second strategy, the third would induce more severe decrease of efficiency and output power of the CLC combined cycle.

Combined Heat and Power: Coal-Fired Air Turbine (CAT)-Cycle Plant

International Nuclear Information System (INIS)

Lee Recca

1999-01-01

By combining an integrated system with a gas turbine, coal-fired air turbine cycle technology can produce energy at an efficiency rate of over 40%, with capital and operating costs below those of competing conventional systems. Read this fact sheet to discover the additional benefits of this exciting new technology

Comparison of algae cultivation methods for bioenergy production using a combined life cycle assessment and life cycle costing approach.

Science.gov (United States)

Resurreccion, Eleazer P; Colosi, Lisa M; White, Mark A; Clarens, Andres F

2012-12-01

Algae are an attractive energy source, but important questions still exist about the sustainability of this technology on a large scale. Two particularly important questions concern the method of cultivation and the type of algae to be used. This present study combines elements of life cycle analysis (LCA) and life cycle costing (LCC) to evaluate open pond (OP) systems and horizontal tubular photobioreactors (PBRs) for the cultivation of freshwater (FW) or brackish-to-saline water (BSW) algae. Based on the LCA, OPs have lower energy consumption and greenhouse gas emissions than PBRs; e.g., 32% less energy use for construction and operation. According to the LCC, all four systems are currently financially unattractive investments, though OPs are less so than PBRs. BSW species deliver better energy and GHG performance and higher profitability than FW species in both OPs and PBRs. Sensitivity analyses suggest that improvements in critical cultivation parameters (e.g., CO(2) utilization efficiency or algae lipid content), conversion parameters (e.g., anaerobic digestion efficiency), and market factors (e.g., costs of CO(2) and electricity, or sale prices for algae biodiesel) could alter these results. Copyright © 2012 Elsevier Ltd. All rights reserved.

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.

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.

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

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.

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.)

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.

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.

Integration of energy-efficient empty fruit bunch drying with gasification/combined cycle systems

International Nuclear Information System (INIS)

Aziz, Muhammad; Prawisudha, Pandji; Prabowo, Bayu; Budiman, Bentang Arief

2015-01-01

Highlights: • Novel integrated drying, gasification and combined cycle for empty fruit bunch. • Application of enhanced process integration to achieve high total energy efficiency. • The technology covers exergy recovery and process integration. • High overall energy efficiency can be achieved (about 44% including drying). - Abstract: A high-energy-efficient process for empty fruit bunch drying with integration to gasification and combined cycle processes is proposed. The enhancement is due to greater exergy recovery and more efficient process integration. Basically, the energy/heat involved in a single process is recovered as much as possible, leading to minimization of exergy destruction. In addition, the unrecoverable energy/heat is utilized for other processes through process integration. During drying, a fluidized bed dryer with superheated steam is used as the main evaporator. Exergy recovery is performed through exergy elevation via compression and effective heat coupling in a dryer and heat exchangers. The dried empty fruit bunches are gasified in a fluidized bed gasifier using air as the fluidizing gas. Furthermore, the produced syngas is utilized as fuel in the combined cycle module. From process analysis, the proposed integrated processes can achieve a relatively high energy efficiency. Compared to a standalone drying process employing exergy recovery, the proposed integrated drying can reduce consumed energy by about 1/3. In addition, the overall integrated processes can reach a total power generation efficiency of about 44%

Propulsion/ASME Rocket-Based Combined Cycle Activities in the Advanced Space Transportation Program Office

Science.gov (United States)

Hueter, Uwe; Turner, James

1998-01-01

NASA's Office Of Aeronautics and Space Transportation Technology (OASTT) has establish three major coals. "The Three Pillars for Success". The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville,Ala. focuses on future space transportation technologies under the "Access to Space" pillar. The Advanced Reusable Technologies (ART) Project, part of ASTP, focuses on the reusable technologies beyond those being pursued by X-33. The main activity over the past two and a half years has been on advancing the rocket-based combined cycle (RBCC) technologies. In June of last year, activities for reusable launch vehicle (RLV) airframe and propulsion technologies were initiated. These activities focus primarily on those technologies that support the year 2000 decision to determine the path this country will take for Space Shuttle and RLV. In February of this year, additional technology efforts in the reusable technologies were awarded. The RBCC effort that was completed early this year was the initial step leading to flight demonstrations of the technology for space launch vehicle propulsion. Aerojet, Boeing-Rocketdyne and Pratt & Whitney were selected for a two-year period to design, build and ground test their RBCC engine concepts. In addition, ASTROX, Pennsylvania State University (PSU) and University of Alabama in Huntsville also conducted supporting activities. The activity included ground testing of components (e.g., injectors, thrusters, ejectors and inlets) and integrated flowpaths. An area that has caused a large amount of difficulty in the testing efforts is the means of initiating the rocket combustion process. All three of the prime contractors above were using silane (SiH4) for ignition of the thrusters. This follows from the successful use of silane in the NASP program for scramjet ignition. However, difficulties were immediately encountered when silane (an 80/20 mixture of hydrogen/silane) was used for rocket

Thermodynamic performance simulation and concise formulas for triple-pressure reheat HRSG of gas–steam combined cycle under off-design condition

International Nuclear Information System (INIS)

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

2016-01-01

exhaust temperature seriously deviates from the design value and several specific operation strategies are employed when the units operate at ultra-low load (50% less combined cycle load/gas turbine load). The prediction results can be utilized as a relative reference. To improve prediction accuracy, a corresponding correction factor can be introduced for modification based on operating experience.

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.

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

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.

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

Study on thermodynamic cycle of high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Qu Xinhe; Yang Xiaoyong; Wang Jie

2017-01-01

The development trend of the (very) High temperature gas-cooled reactor is to gradually increase the reactor outlet temperature. The different power conversion units are required at the different reactor outlet temperature. In this paper, for the helium turbine direct cycle and the combined cycle of the power conversion unit of the High temperature gas-cooled reactor, the mathematic models are established, and three cycle plans are designed. The helium turbine direct cycle is a Brayton cycle with recuperator, precooler and intercooler. In the combined cycle plan 1, the topping cycle is a simple Brayton cycle without recuperator, precooler and intercooler, and the bottoming cycle is based on the steam parameters (540deg, 6 MPa) recommended by Siemens. In the combined cycle plan 2, the topping cycle also is a simple Brayton cycle, and the bottoming cycle which is a Rankine cycle with reheating cycle is based on the steam parameters of conventional subcritical thermal power generation (540degC, 18 MPa). The optimization results showed that the cycle efficiency of the combined cycle plan 2 is the highest, the second is the helium turbine direct cycle, and the combined cycle plan 2 is the lowest. When the reactor outlet temperature is 900degC and the pressure ratio is 2.02, the cycle efficiency of the combined cycle plan 2 can reach 49.7%. The helium turbine direct cycle has a reactor inlet temperature above 500degC due to the regenerating cycle, so it requires a cooling circuit for the internal wall of the reactor pressure vessel. When the reactor outlet temperature increases, the increase of the pressure ratio required by the helium turbine direct cycle increases may bring some difficulties to the design and manufacture of the magnetic bearings. For the combined cycle, the reactor inlet temperature can be controlled below than 370degC, so the reactor pressure vessel can use SA533 steel without cooling the internal wall of the reactor pressure vessel. The pressure

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

Pyroelectric Energy Harvesting: With Thermodynamic-Based Cycles

OpenAIRE

Saber Mohammadi; Akram Khodayari

2012-01-01

This work deals with energy harvesting from temperature variations using ferroelectric materials as a microgenerator. The previous researches show that direct pyroelectric energy harvesting is not effective, whereas thermodynamic-based cycles give higher energy. Also, at different temperatures some thermodynamic cycles exhibit different behaviours. In this paper pyroelectric energy harvesting using Lenoir and Ericsson thermodynamic cycles has been studied numerically and the two cycles were c...

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

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

Thermal characteristics of combined thermoelectric generator and refrigeration cycle

International Nuclear Information System (INIS)

Yilbas, Bekir S.; Sahin, Ahmet Z.

2014-01-01

Highlights: • TEM location in between the evaporator and condenser results in low coefficient of performance. • TEM location in between condenser and its ambient improves coefficient of performance of the combined system. • High temperature ratio enhances coefficient of performance of combined system. • Certain values of parameters enhance combined system performance. - Abstract: A combined thermal system consisting of a thermoelectric generator and a refrigerator is considered and the effect of location of the thermoelectric generator, in the refrigeration cycle, on the performance characteristics of the combined system is investigated. The operating conditions and their influence on coefficient of performance of the combined system are examined through introducing the dimensionless parameters, such as λ(λ = Q HTE /Q H , where Q HTE is heat transfer to the thermoelectric generator from the condenser, Q H is the total heat transfer from the condenser to its ambient), temperature ratio (θ L = T L /T H , where T L is the evaporator temperature and T H is the condenser temperature), r C (r C = C L /C H , where C L is the thermal capacitance due to heat transfer to evaporator and C H , is the thermal capacitance due to heat rejected from the condenser), θ W (θ W = T W /T H , where T W is the ambient temperature), θ C (θ C = T C /T H , where T C is the cold space temperature). It is found that the location of the thermoelectric generator in between the condenser and the evaporator decreases coefficient of performance of the combined system. Alternatively, the location of thermoelectric device in between the condenser and its ambient enhances coefficient of performance of the combined system. The operating parameters has significant effect on the performance characteristics of the combined system; in which case temperature ratio (θ L ) within the range of 0.68–0.70, r C = 2.5, θ W = 0.85, and θ C = 0.8 improve coefficient of performance of the

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

CycleBase.org - a comprehensive multi-organism online database of cell-cycle experiments

DEFF Research Database (Denmark)

Gauthier, Nicholas Paul; Larsen, Malene Erup; Wernersson, Rasmus

2007-01-01

The past decade has seen the publication of a large number of cell-cycle microarray studies and many more are in the pipeline. However, data from these experiments are not easy to access, combine and evaluate. We have developed a centralized database with an easy-to-use interface, Cyclebase...

Combined cycles for pipeline compressor drives using heat

International Nuclear Information System (INIS)

Malewski, W.F.; Holldorff, G.M.

1979-01-01

Combined cycles for pipeline-booster stations using waste heat from gas turbines exhaust can improve the overall efficiency of such stations remarkably. Several working fluids are suitable. Due to existing criteria for selecting a working medium under mentioned conditions, water, ammonia, propane and butane can be considered as practical working fluids. The investigations have shown that: (1) ammonia is advantageous at low exhaust gas and ambient temperatures, (2) water is most effective at high exhaust gas and ambient temperatures, and (3), additionally, hydrocarbons are suitable in a medium range for exhaust gas and condensing temperatures. Not only thermodynamic but also operational features have to be considered. There is not one optimum working fluid but a best one suitable according to the prevailing site conditions

Influence of precooling cooling air on the performance of a gas turbine combined cycle

Energy Technology Data Exchange (ETDEWEB)

Kwon, Ik Hwan; Kang, Do Won; Kang, Soo Young; Kim, Tong Seop [Inha Univ., Incheon (Korea, Republic of)

2012-02-15

Cooling of hot sections, especially the turbine nozzle and rotor blades, has a significant impact on gas turbine performance. In this study, the influence of precooling of the cooling air on the performance of gas turbines and their combined cycle plants was investigated. A state of the art F class gas turbine was selected, and its design performance was deliberately simulated using detailed component models including turbine blade cooling. Off design analysis was used to simulate changes in the operating conditions and performance of the gas turbines due to precooling of the cooling air. Thermodynamic and aerodynamic models were used to simulate the performance of the cooled nozzle and rotor blade. In the combined cycle plant, the heat rejected from the cooling air was recovered at the bottoming steam cycle to optimize the overall plant performance. With a 200K decrease of all cooling air stream, an almost 1.78% power upgrade due to increase in main gas flow and a 0.70 percent point efficiency decrease due to the fuel flow increase to maintain design turbine inlet temperature were predicted.

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.

Analysis of the effects of combining air separation with combustion in a zero emissions (ZEITMOP) cycle

International Nuclear Information System (INIS)

Foy, Kirsten; McGovern, Jim

2007-01-01

The ZEITMOP cycle is a zero emissions (oxyfuel) power plant cycle proposed by Evgeny Yantovski that uses oxygen ion transport membranes to extract the oxygen required for combustion from air. A current proposed configuration of the cycle requires an oxygen ion transport membrane air separation unit operating at 920 deg. C and a separate combustion chamber operating at 1400 deg. C. If oxygen is consumed by a chemical reaction on the permeate side of an oxygen transport membrane, the oxygen flux is larger, so the air separation unit can be physically smaller. In addition, if this reaction is exothermic, the air separation unit is heated by the reaction, requiring no additional heating. Combustion fulfils both of these requirements, so combustion in the oxygen transport membrane air separation unit would allow a smaller air separation unit, which would also act as a combustion chamber. Unfortunately, a combustion temperature of 1400 deg. C will damage most oxygen transport membranes available today. However, new materials are continually being developed and investigated, so it may be possible to have an oxygen transport membrane chamber operating at 1400 deg. C in the short to medium term future. Alternatively the combustion chamber may be cooled, allowing it to operate at more realistic temperatures for currently available oxygen transport membranes. Controlling the operation temperature of the combined unit requires changing the mass flow rates of various streams of fluid in the cycle. This will have an effect on the work and heat transfers in the cycle. It is possible to calculate the theoretical effects of these changes in temperature. This paper presents an analysis investigating the impact of combining the air separator and the combustion chamber. The efficiency of the cycle was calculated at various operation temperatures for the combined oxygen transport membrane combustion chamber. The results were compared to the efficiency of the current cycle. The changes

Exergy based parametric analysis of a combined reheat regenerative thermal power plant and water–LiBr vapor absorption refrigeration system

International Nuclear Information System (INIS)

Gogoi, T.K.; Talukdar, K.

2014-01-01

Highlights: • Exergy analysis of a combined power–absorption cooling system is provided. • Exergetic efficiency of the power cycle and absorption cooling system are calculated. • Irreversibility in each component and total system irreversibility are calculated. • Effect of operating parameters on exergetic performance and irreversibility is analyzed. • Optimum operating parameters are identified based on energy and exergy based results. - Abstract: In this paper, exergy analysis of a combined reheat regenerative steam turbine (ST) based power cycle and water–LiBr vapor absorption refrigeration system (VARS) is presented. Exergetic efficiency of the power cycle and VARS, energy utilization factor (EUF) of the combined system (CS) and irreversibility in each system component are calculated. The effect of fuel flow rate, boiler pressure, cooling capacity and VARS components’ temperature on performance, component and total system irreversibility is analyzed. The second law based results indicate optimum performance at 150 bar boiler pressure and VARS generator, condenser, evaporator and absorber temperature of 80 °C, 37.5 °C, 15 °C and 35 °C respectively. The present exergy based results conform well to the first law based results obtained in a previous analysis done on the same combined system. Irreversibility distribution among various power cycle components shows the highest irreversibility in the cooling tower. Irreversibility of the exhaust flue gas leaving the boiler and the boiler are the next major contributors. Among the VARS components, exergy destruction in the generator is the highest followed by irreversibility contribution of the absorber, condenser and the evaporator

Investigation of thermodynamic performances for two solar-biomass hybrid combined cycle power generation systems

International Nuclear Information System (INIS)

Liu, Qibin; Bai, Zhang; Wang, Xiaohe; Lei, Jing; Jin, Hongguang

2016-01-01

Highlights: • Two solar-biomass hybrid combined cycle power generation systems are proposed. • The characters of the two proposed systems are compared. • The on-design and off-design properties of the system are numerically investigated. • The favorable performances of thermochemical hybrid routine are validated. - Abstract: Two solar-biomass hybrid combined cycle power generation systems are proposed in this work. The first system employs the thermochemical hybrid routine, in which the biomass gasification is driven by the concentrated solar energy, and the gasified syngas as a solar fuel is utilized in a combined cycle for generating power. The second system adopts the thermal integration concept, and the solar energy is directly used to heat the compressed air in the topping Brayton cycle. The thermodynamic performances of the developed systems are investigated under the on-design and off-design conditions. The advantages of the hybrid utilization technical mode are demonstrated. The solar energy can be converted and stored into the chemical fuel by the solar-biomass gasification, with the net solar-to-fuel efficiency of 61.23% and the net solar share of 19.01% under the specific gasification temperature of 1150 K. Meanwhile, the proposed system with the solar thermochemical routine shows more favorable behaviors, the annual system overall energy efficiency and the solar-to-electric efficiency reach to 29.36% and 18.49%, while the with thermal integration concept of 28.03% and 15.13%, respectively. The comparison work introduces a promising approach for the efficient utilization of the abundant solar and biomass resources in the western China, and realizes the mitigation of CO_2 emission.

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)

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

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

of less healthy foods (sugar-sweetened beverages). Further studies are needed to test whether this conclusion holds within a more comprehensive assessment of environmental and nutritional health impacts. Conclusions This case study provides the first quantitative epidemiology-based estimate......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......-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...

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

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

Combined cycle versus one thousand diesel power plants: pollutant emissions, ecological efficiency and economic analysis

International Nuclear Information System (INIS)

Silveira, Jose Luz; de Carvalho, Joao Andrade; de Castro Villela, Iraides Aparecida

2007-01-01

The increase in the use of natural gas in Brazil has stimulated public and private sectors to analyse the possibility of using combined cycle systems for generation of electrical energy. Gas turbine combined cycle power plants are becoming increasingly common due to their high efficiency, short lead times, and ability to meet environmental standards. Power is produced in a generator linked directly to the gas turbine. The gas turbine exhaust gases are sent to a heat recovery steam generator to produce superheated steam that can be used in a steam turbine to produce additional power. In this paper a comparative study between a 1000 MW combined cycle power plant and 1000kW diesel power plant is presented. In first step, the energetic situation in Brazil, the needs of the electric sector modification and the needs of demand management and integrated means planning are clarified. In another step the characteristics of large and small thermoelectric power plants that use natural gas and diesel fuel, respectively, are presented. The ecological efficiency levels of each type of power plant is considered in the discussion, presenting the emissions of particulate material, sulphur dioxide (SO 2 ), carbon dioxide (CO 2 ) and nitrogen oxides (NO x ). (author)

Improvement of performance operation and cycle efficiency of Al Anbar combined power plant

International Nuclear Information System (INIS)

Jabbar, Mohammed Q.

2014-01-01

The present work will be focusing on available solution which can serve to increase total efficiency of Al Anbar combined cycle power plant - CCPP, and thus to improve the operation performance as much as possible in order to decrease hydrocarbon, CO2, NOx emissions to environment.The simulation and calculations were performed by program software cycle-tempo software. The results were compared with basic design of Alanbar power plant after making modernization with solar tower receiver system-STRS, which represented a heat source in preheat process for a compressor air. Key Words: CCPP, STRS, Solar potential energy, fuel consumption, hydrocarbon emission

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

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...... 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...

Externally-fired combined cycle: An effective coal fueled technology for repowering and new generation

Energy Technology Data Exchange (ETDEWEB)

Stoddard, L.E.; Bary, M.R. [Black and Veatch, Kansas City, MO (United States); Gray, K.M. [Pennsylvania Electric Co., Johnstown, PA (United States); LaHaye, P.G. [Hague International, South Portland, ME (United States)

1995-06-01

The Externally-Fired Combined Cycle (EFCC) is an attractive emerging technology for powering high efficiency combined gas and steam turbine cycles with coal or other ash bearing fuels. In the EFCC, the heat input to a gas turbine is supplied indirectly through a ceramic air heater. The air heater, along with an atmospheric coal combustor and ancillary equipment, replaces the conventional gas turbine combustor. A steam generator located downstream from the ceramic air heater and steam turbine cycle, along with an exhaust cleanup system, completes the combined cycle. A key element of the EFCC Development Program, the 25 MMBtu/h heat-input Kennebunk Test Facility (KTF), has recently begun operation. The KTF has been operating with natural gas and will begin operating with coal in early 1995. The US Department of Energy selected an EFCC repowering of the Pennsylvania Electric Company`s Warren Station for funding under the Clean Coal Technology Program Round V. The project focuses on repowering an existing 48 MW (gross) steam turbine with an EFCC power island incorporating a 30 MW gas turbine, for a gross power output of 78 MW and a net output of 72 MW. The net plant heat rate will be decreased by approximately 30% to below 9,700 Btu/kWh. Use of a dry scrubber and fabric filter will reduce sulfur dioxide (SO{sub 2}) and particulate emissions to levels under those required by the Clean Air Act Amendments (CAAA) of 1990. Nitrogen oxides (NO{sub x}) emissions are controlled by the use of staged combustion. The demonstration project is currently in the engineering phase, with startup scheduled for 1997. This paper discusses the background of the EFCC, the KTF, the Warren Station EFCC Clean Coal Technology Demonstration Project, the commercial plant concept, and the market potential for the EFCC.

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.

Integrated gasification gas combined cycle plant with membrane reactors: Technological and economical analysis

International Nuclear Information System (INIS)

Amelio, Mario; Morrone, Pietropaolo; Gallucci, Fausto; Basile, Angelo

2007-01-01

In the present work, the capture and storage of carbon dioxide from the fossil fuel power plant have been considered. The main objective was to analyze the thermodynamic performances and the technological aspects of two integrated gasification gas combined cycle plants (IGCC), as well as to give a forecast of the investment costs for the plants and the resulting energy consumptions. The first plant considered is an IGCC* plant (integrated gasification gas combined cycle plant with traditional shift reactors) characterized by the traditional water gas shift reactors and a CO 2 physical adsorption system followed by the power section. The second one is an IGCC M plant (integrated gasification gas combined cycle plant with membrane reactor) where the coal thermal input is the same as the first one, but the traditional shift reactors and the physical adsorption unit are replaced by catalytic palladium membrane reactors (CMR). In the present work, a mono-dimensional computational model of the membrane reactor was proposed to simulate and evaluate the capability of the IGCC M plant to capture carbon dioxide. The energetic performances, efficiency and net power of the IGCC* and IGCC M plants were, thus, compared, assuming as standard a traditional IGCC plant without carbon dioxide capture. The economical aspects of the three plants were compared through an economical analysis. Since the IGCC* and IGCC M plants have additional costs related to the capture and disposal of the carbon dioxide, a Carbon Tax (adopted in some countries like Sweden) proportional to the number of kilograms of carbon dioxide released in the environment was assumed. According to the economical analysis, the IGCC M plant proved to be more convenient than the IGCC* one

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.

Thermodynamic analysis on theoretical models of cycle combined heat exchange process: The reversible heat exchange process

International Nuclear Information System (INIS)

Zhang, Chenghu; Li, Yaping

2017-01-01

Concept of reversible heat exchange process as the theoretical model of the cycle combined heat exchanger could be useful to determine thermodynamics characteristics and the limitation values in the isolated heat exchange system. In this study, the classification of the reversible heat exchange processes is presented, and with the numerical method, medium temperature variation tendency and the useful work production and usage in the whole process are investigated by the construction and solution of the mathematical descriptions. Various values of medium inlet temperatures and heat capacity ratio are considered to analyze the effects of process parameters on the outlet temperature lift/drop. The maximum process work transferred from the Carnot cycle region to the reverse cycle region is also researched. Moreover, influence of the separating point between different sub-processes on temperature variation profile and the process work production are analyzed. In addition, the heat-exchange-enhancement-factor is defined to study the enhancement effect of the application of the idealized process in the isolated heat exchange system, and the variation degree of this factor with process parameters change is obtained. The research results of this paper can be a theoretical guidance to construct the cycle combined heat exchange process in the practical system. - Highlights: • A theoretical model of Cycle combined heat exchange process is proposed. • The classification of reversible heat exchange process are presented. • Effects of Inlet temperatures and heat capacity ratio on process are analyzed. • Process work transmission through the whole process is studied. • Heat-exchange-enhancement-factor can be a criteria to express the application effect of the idealized process.

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.

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%.

Novel integrated gasification combined cycles with a carbon dioxide recovery option

Energy Technology Data Exchange (ETDEWEB)

Lawton, J.

1997-08-01

Two novel combined cycle configurations offering potential to reduce the cost of electricity from coal-fired IGCCs were investigated - one based on the use of flue gas recycling with heat recovery to the recycled stream, the other, aimed at removing carbon dioxide, using flue gas recycle and heat recovery but with oxygen as the oxidant in the gas turbine. The investigation included the use of fuels other than coal. It was found that gasification efficiency was increased by use of a coal/Orimulsion slurry. Flue gas recycling at 1 bar for the industrial gas turbine offered a gain of about 0.4 percentage points. In a standard IGCC the industrial gas turbine showed an advantage of 1.5 percentage points over the aero-derived machine. The least cost electricity with CO{sub 2} removal was achieved using an oxygen-fed industrial gas turbine with flue gas recycling and recovery. Several recommendations are made for further studies to reduce costs of electricity production. 11 refs., 3 figs., 5 tabs., 1 app.

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)

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.

The IVF Outcome Counseling Based on the Model Combining DHEAS and Age in Patients with Low AMH Prior to the First Cycle of GnRH Antagonist Protocol of Ovarian Stimulation

Directory of Open Access Journals (Sweden)

Miro Šimun Alebić

2013-01-01

Full Text Available Objective. To investigate the endocrine and/or clinical characteristics of women with low anti-Müllerian hormone (AMH that could improve the accuracy of IVF outcome prediction based on the female age alone prior to the first GnRH antagonist IVF cycle. Methods. Medical records of 129 patients with low AMH level (<6.5 pmol/L who underwent their first GnRH antagonist ovarian stimulation protocol for IVF/ICSI were retrospectively analyzed. The main outcome measure was the area under the ROC curve (AUC-ROC for the models combining age and other potential predictive factors for the clinical pregnancy. Results. Clinical pregnancy rate (CPR per initiated cycles was 11.6%. For the prediction of clinical pregnancy, DHEAS and age showed AUC-ROC of 0.726 (95%CI 0.641–0.801 and 0.662 (95%CI 0.573–0.743, respectively (. The predictive accuracy of the model combining age and DHEAS (AUC-ROC 0.796; 95%CI 0.716–0.862 was significantly higher compared to that of age alone (. In patients <37.5 years with DHEAS  pmol/L, 60% (9/15 of all pregnancies were achieved with CPR of 37.5%. Conclusions. DHEAS appears to be predictive for clinical pregnancy in younger women (<37.5 years with low AMH after the first GnRH antagonist IVF cycle. Therefore, DHEAS-age model could refine the pretreatment counseling on pregnancy prospects following IVF.

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......When the Norwegian government introduced the CO2 tax for hydrocarbon fuels, the challenge became to improve the performance of off-shore power systems. An oil and gas platform typically operates on an island (stand-alone system) and the power demand is covered by two or more gas turbines. In order...... 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...

Partaking in cycling, at what cost? : determinants of cycling expenses

NARCIS (Netherlands)

Thibaut, E.; Vos, S.B.; Lagae, W.; Van Puyenbroeck, T.; Scheerder, J.

2016-01-01

This study analyses the determinants of cycling expenditure by means of a Tobit regression analysis, based on a dataset of 5,157 cyclists. Using a heterodox economic framework, 23 different variables are combined into two commonly used variable groups (socio-demographics, sports intensity variables)

Systems Analyses of Advanced Brayton Cycles

Energy Technology Data Exchange (ETDEWEB)

A.D. Rao; D.J. Francuz; J.D. Maclay; J. Brouwer; A. Verma; M. Li; G.S. Samuelsen

2008-09-30

The main objective is to identify and assess advanced improvements to the Brayton Cycle (such as but not limited to firing temperature, pressure ratio, combustion techniques, intercooling, fuel or combustion air augmentation, enhanced blade cooling schemes) that will lead to significant performance improvements in coal based power systems. This assessment is conducted in the context of conceptual design studies (systems studies) that advance state-of-art Brayton cycles and result in coal based efficiencies equivalent to 65% + on natural gas basis (LHV), or approximately an 8% reduction in heat rate of an IGCC plant utilizing the H class steam cooled gas turbine. H class gas turbines are commercially offered by General Electric and Mitsubishi for natural gas based combined cycle applications with 60% efficiency (LHV) and it is expected that such machine will be offered for syngas applications within the next 10 years. The studies are being sufficiently detailed so that third parties will be able to validate portions or all of the studies. The designs and system studies are based on plants for near zero emissions (including CO{sub 2}). Also included in this program is the performance evaluation of other advanced technologies such as advanced compression concepts and the fuel cell based combined cycle. The objective of the fuel cell based combined cycle task is to identify the desired performance characteristics and design basis for a gas turbine that will be integrated with an SOFC in Integrated Gasification Fuel Cell (IGFC) applications. The goal is the conceptualization of near zero emission (including CO{sub 2} capture) integrated gasification power plants producing electricity as the principle product. The capability of such plants to coproduce H{sub 2} is qualitatively addressed. Since a total systems solution is critical to establishing a plant configuration worthy of a comprehensive market interest, a baseline IGCC plant scheme is developed and used to study

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

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

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 cycle COC as a valuable treatment option with high satisfaction, high adherence, and reduced heavy menstrual bleeding.

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

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%

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.

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.

The potential for control of carbon dioxide emissions from integrated gasification/combined-cycle systems

Energy Technology Data Exchange (ETDEWEB)

Livengood, C.D.; Doctor, R.D.; Molburg, J.C.; Thimmapuram, P.; Berry, G.F.

1994-06-01

Initiatives to limit carbon dioxide (CO{sub 2}) emissions have drawn considerable interest to integrated gasification/combined-cycle (IGCC) power generation, a process that reduces CO{sub 2} production through efficient fuel used is amenable to CO{sub 2} capture. This paper presents a comparison of energy systems that encompass fuel supply, an IGCC system, CO{sub 2} recovery using commercial technologies, CO{sub 2} transport by pipeline, and land-based sequestering in geological reservoirs. The intent is to evaluate the energy-efficiency impacts of controlling CO{sub 2} in such systems and to provide the CO{sub 2} budget, or an to equivalent CO{sub 2}`` budget, associated with each of the individual energy-cycle steps. The value used for the ``equivalent CO{sub 2}`` budget is 1 kg/kWh CO{sub 2}. The base case for the comparison is a 457-MW IGCC system that uses an air-blown Kellogg-Rust-Westinghouse (KRW) agglomerating fluidized-bed gasifier, Illinois No. 6 bituminous coal, and in-bed sulfur removal. Mining, preparation, and transportation of the coal and limestone result in a net system electric power production of 454 MW with a 0.835 kg/kwh CO{sub 2} release rate. For comparison, the gasifier output is taken through a water-gas shift to convert CO to CO{sub 2} and then processed in a glycol-based absorber unit to recover CO{sub 2} Prior to the combustion turbine. A 500-km pipeline then transports the CO{sub 2} for geological sequestering. The net electric power production for the system with CO{sub 2} recovery is 381 MW with a 0.156 kg/kwh CO{sub 2} release rate.

Optimisation of Combined Cycle Gas Turbine Power Plant in Intraday Market: Riga CHP-2 Example

Science.gov (United States)

Ivanova, P.; Grebesh, E.; Linkevics, O.

2018-02-01

In the research, the influence of optimised combined cycle gas turbine unit - according to the previously developed EM & OM approach with its use in the intraday market - is evaluated on the generation portfolio. It consists of the two combined cycle gas turbine units. The introduced evaluation algorithm saves the power and heat balance before and after the performance of EM & OM approach by making changes in the generation profile of units. The aim of this algorithm is profit maximisation of the generation portfolio. The evaluation algorithm is implemented in multi-paradigm numerical computing environment MATLab on the example of Riga CHP-2. The results show that the use of EM & OM approach in the intraday market can be profitable or unprofitable. It depends on the initial state of generation units in the intraday market and on the content of the generation portfolio.

A synthesis/design optimization algorithm for Rankine cycle based energy systems

International Nuclear Information System (INIS)

Toffolo, Andrea

2014-01-01

The algorithm presented in this work has been developed to search for the optimal topology and design parameters of a set of Rankine cycles forming an energy system that absorbs/releases heat at different temperature levels and converts part of the absorbed heat into electricity. This algorithm can deal with several applications in the field of energy engineering: e.g., steam cycles or bottoming cycles in combined/cogenerative plants, steam networks, low temperature organic Rankine cycles. The main purpose of this algorithm is to overcome the limitations of the search space introduced by the traditional mixed-integer programming techniques, which assume that possible solutions are derived from a single superstructure embedding them all. The algorithm presented in this work is a hybrid evolutionary/traditional optimization algorithm organized in two levels. A complex original codification of the topology and the intensive design parameters of the system is managed by the upper level evolutionary algorithm according to the criteria set by the HEATSEP method, which are used for the first time to automatically synthesize a “basic” system configuration from a set of elementary thermodynamic cycles. The lower SQP (sequential quadratic programming) algorithm optimizes the objective function(s) with respect to cycle mass flow rates only, taking into account the heat transfer feasibility constraint within the undefined heat transfer section. A challenging example of application is also presented to show the capabilities of the algorithm. - Highlights: • Energy systems based on Rankine cycles are used in many applications. • A hybrid algorithm is proposed to optimize the synthesis/design of such systems. • The topology of the candidate solutions is not limited by a superstructure. • Topology is managed by the genetic operators of the upper level algorithm. • The effectiveness of the algorithm is proved in a complex test case

Production costs: U.S. gas turbine ampersand combined-cycle power plants

International Nuclear Information System (INIS)

Anon.

1992-01-01

This fourth edition of UDI's gas turbine O ampersand M cost report gives 1991 operation and maintenance expenses for over 450 US gas turbine power plants. Modeled on UDI's popular series of O ampersand M cost reports for US steam-electric plants, this report shows operator and plant name, plant year-in-service, installed capacity, 1991 net generation, total fuel expenses, total non-fuel O ampersand M expenses, total production costs, and current plant capitalization. Coverage includes over 90 percent of the utility-owned gas/combustion turbine and combined-cycle plants installed in the country

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.

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

Report on studies on closed cycle MHD power generation; Closed cycle MHD hatsuden kento hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

1991-04-01

Summarized herein are results of the studies on closed cycle MHD (CCMHD) power generation by the study committee. The studied system is based on the MHD gas turbine combined Brayton cycle of about 500,000 kW in output power, firing natural gas as the fuel, and the conceptual design works therefor are completed. The major findings are: the overall plant efficiency: 54.2% at the power transmission side, plot area required per unit power output: 0.04 m{sup 2}/KW, unit construction cost: 251,000 yen/KW, and unit power generation cost: 10.2 yen/KWh. This system will be more operable than the gas turbine combined cycle with steam system, because start-up time, output change rate, optimum load and so on are constrained not on the power generator side but on the gas turbine side. The expected environmental effects include the exhaust gas NOX concentration being equivalent with that associated with the conventional power generator of 2-stage combustion system, quantity of combustion gases to be treated being approximately 40% of that associated with the gas turbine combined cycle, and reduced CO2 gas emissions, resulting from enhanced power generation efficiency. It is expected that the CCMHD system can exhibit higher efficiency than the high-temperature gas turbine combined cycle system. (NEDO)

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)

Optimisation of Combined Cycle Gas Turbine Power Plant in Intraday Market: Riga CHP-2 Example

Directory of Open Access Journals (Sweden)

Ivanova P.

2018-02-01

Full Text Available In the research, the influence of optimised combined cycle gas turbine unit – according to the previously developed EM & OM approach with its use in the intraday market – is evaluated on the generation portfolio. It consists of the two combined cycle gas turbine units. The introduced evaluation algorithm saves the power and heat balance before and after the performance of EM & OM approach by making changes in the generation profile of units. The aim of this algorithm is profit maximisation of the generation portfolio. The evaluation algorithm is implemented in multi-paradigm numerical computing environment MATLab on the example of Riga CHP-2. The results show that the use of EM & OM approach in the intraday market can be profitable or unprofitable. It depends on the initial state of generation units in the intraday market and on the content of the generation portfolio.

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

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.

Prioritization of Bioethanol Production Pathways in China based on Life Cycle Sustainability Assessment and Multi-Criteria Decision-Making

DEFF Research Database (Denmark)

Ren, Jingzheng; Manzardo, Alessandro; Mazzi, Anna

2015-01-01

Purpose The study objectives are two-fold: (i) combining the life cycle sustainability assessment (LCSA) framework and the multi-criteria decision-making (MCDM) methodology for sustainability assessment; (ii) determining the most sustainable scenario for bioethanol production in China according......’s proposed method investigates an illustrative case about three alternative bioethanol production scenarios (wheat-based, corn-based and cassava-based): the prior sequence (based on the sustainability performances) in descending order is cassava-based, corn-based and wheat-based. The proposed methodology...... is to test the combination of a MCDM methodology and LCSA for sustainability decision-making by studying three alternative pathways for bioethanol production in China. The proposed method feasibly enables the decision-makers/stakeholders to find the most sustainable scenario to achieve their objectives among...

Simulation of Cycle-to-Cycle Variation in Dual-Fuel Engines

KAUST Repository

Jaasim, Mohammed

2017-03-13

Standard practices of internal combustion (IC) engine experiments are to conduct the measurements of quantities averaged over a large number of cycles. Depending on the operating conditions, the cycle-to-cycle variation (CCV) of quantities, such as the indicated mean effective pressure (IMEP) are observed at different levels. Accurate prediction of CCV in IC engines is an important but challenging task. Computational fluid dynamics (CFD) simulations using high performance computing (HPC) can be used effectively to visualize such 3D spatial distributions. In the present study, a dual fuel large engine is considered, with natural gas injected into the manifold accompanied with direct injection of diesel pilot fuel to trigger ignition. Multiple engine cycles in 3D are simulated in series as in the experiments to investigate the potential of HPC based high fidelity simulations to accurately capture the cycle to cycle variation in dual fuel engines. Open cycle simulations are conducted to predict the combined effect of the stratification of fuel-air mixture, temperature and turbulence on the CCV of pressure. The predicted coefficient of variation (COV) of pressure compared to the results from closed cycle simulations and the experiments.

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)

A hybrid mammalian cell cycle model

Directory of Open Access Journals (Sweden)

Vincent Noël

2013-08-01

Full Text Available Hybrid modeling provides an effective solution to cope with multiple time scales dynamics in systems biology. Among the applications of this method, one of the most important is the cell cycle regulation. The machinery of the cell cycle, leading to cell division and proliferation, combines slow growth, spatio-temporal re-organisation of the cell, and rapid changes of regulatory proteins concentrations induced by post-translational modifications. The advancement through the cell cycle comprises a well defined sequence of stages, separated by checkpoint transitions. The combination of continuous and discrete changes justifies hybrid modelling approaches to cell cycle dynamics. We present a piecewise-smooth version of a mammalian cell cycle model, obtained by hybridization from a smooth biochemical model. The approximate hybridization scheme, leading to simplified reaction rates and binary event location functions, is based on learning from a training set of trajectories of the smooth model. We discuss several learning strategies for the parameters of the hybrid model.

An evaluation of the performance of an integrated solar combined cycle plant provided with air-linear parabolic collectors

International Nuclear Information System (INIS)

Amelio, Mario; Ferraro, Vittorio; Marinelli, Valerio; Summaria, Antonio

2014-01-01

An evaluation of the performance of an innovative solar system integrated in a combined cycle plant is presented, in which the heat transfer fluid flowing in linear parabolic collectors is the same oxidant air that is introduced into the combustion chamber of the plant. This peculiarity allows a great simplification of the plant. There is a 22% saving of fossil fuel results in design conditions and 15.5% on an annual basis, when the plant works at nominal volumetric flow rate in the daily hours. The net average year efficiency is 60.9% against the value of 51.4% of a reference combined cycle plant without solar integration. Moreover, an economic evaluation of the plant is carried out, which shows that the extra-cost of the solar part is recovered in about 5 years. - Highlights: • A model to calculate an innovative ISCCS (Integrated solar Combined Cycle Systems) solar plant is presented. • The plant uses air as heat transfer fluid as well as oxidant in the combustor. • The plant presents a very high thermodynamic efficiency. • The plant is very simple in comparison with existing ISCCS

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

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%.

Analysis of a novel solar energy-powered Rankine cycle for combined power and heat generation using supercritical carbon dioxide

Energy Technology Data Exchange (ETDEWEB)

Zhang, X.R.; Yamaguchi, H.; Uneno, D. [Department of Mechanical Engineering, Doshisha University, Kyoto 630-0321 (Japan); Fujima, K. [Mayekawa MFG Co., Ltd., 2000 Tatsuzawa Moriya-city, Ibaraki-Pref. 302-0118 (Japan); Enomoto, M. [Showa Denko K. K., 1-480, Inuzuka, Oyama-city, Tochigi 323-8679 (Japan); Sawada, N. [Showa Tansan Co., Ltd., 7-1, Ogimachi, Kawasaki-Ku, Kawasaki-city, Kanagawa 210-0867 (Japan)

2006-10-15

Theoretical analysis of a solar energy-powered Rankine thermodynamic cycle utilizing an innovative new concept, which uses supercritical carbon dioxide as a working fluid, is presented. In this system, a truly 'natural' working fluid, carbon dioxide, is utilized to generate firstly electricity power and secondly high-grade heat power and low-grade heat power. The uniqueness of the system is in the way in which both solar energy and carbon dioxide, available in abundant quantities in all parts of the world, are simultaneously used to build up a thermodynamic cycle and has the potential to reduce energy shortage and greatly reduce carbon dioxide emissions and global warming, offering environmental and personal safety simultaneously. The system consists of an evacuated solar collector system, a power-generating turbine, a high-grade heat recovery system, a low-grade heat recovery system and a feed pump. The performances of this CO{sub 2}-based Rankine cycle were theoretically investigated and the effects of various design conditions, namely, solar radiation, solar collector area and CO{sub 2} flow rate, were studied. Numerical simulations show that the proposed system may have electricity power efficiency and heat power efficiency as high as 11.4% and 36.2%, respectively. It is also found that the cycle performances strongly depend on climate conditions. Also the electricity power and heat power outputs increase with the collector area and CO{sub 2} flow rate. The estimated COP{sub power} and COP{sub heat} increase with the CO{sub 2} flow rate, but decrease with the collector area. The CO{sub 2}-based cycle can be optimized to provide maximum power, maximum heat recovery or a combination of both. The results suggest the potential of this new concept for applications to electricity power and heat power generation. (author)

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.

Sub-50-as isolated extreme ultraviolet continua generated by 1.6-cycle near-infrared pulse combined with double optical gating scheme

Science.gov (United States)

Oguri, Katsuya; Mashiko, Hiroki; Ogawa, Tatsuya; Hanada, Yasutaka; Nakano, Hidetoshi; Gotoh, Hideki

2018-04-01

We demonstrate the generation of ultrabroad bandwidth attosecond continua extending to sub-50-as duration in the extreme ultraviolet (EUV) region based on a 1.6-cycle Ti:sapphire laser pulse. The combination of the amplitude gating scheme with a sub-two-cycle driver pulse and the double optical gating scheme achieves the continuum generation with a bandwidth of 70 eV at the full width at half maximum near the peak photon energy of 140 eV, which supports a Fourier-transform-limited pulse duration as short as 32 as. The carrier-envelope-phase (CEP) dependence of the attosecond continua shows a single-peak structure originating from the half-cycle cut-off at appropriate CEP values, which strongly indicates the generation of a single burst of an isolated attosecond pulse. Our approach suggests a possibility for isolated sub-50-as pulse generation in the EUV region by compensating for the intrinsic attosecond chirp with a Zr filter.

A post-Cassini view of Titan's methane-based hydrologic cycle

Science.gov (United States)

Hayes, Alexander G.; Lorenz, Ralph D.; Lunine, Jonathan I.

2018-05-01

The methane-based hydrologic cycle on Saturn's largest moon, Titan, is an extreme analogue to Earth's water cycle. Titan is the only planetary body in the Solar System, other than Earth, that is known to have an active hydrologic cycle. With a surface pressure of 1.5 bar and temperatures of 90 to 95 K, methane and ethane condense out of a nitrogen-based atmosphere and flow as liquids on the moon's surface. Exchange processes between atmospheric, surface and subsurface reservoirs produce methane and ethane cloud systems, as well as erosional and depositional landscapes that have strikingly similar forms to their terrestrial counterparts. Over its 13-year exploration of the Saturn system, the Cassini-Huygens mission revealed that Titan's hydrocarbon-based hydrology is driven by nested methane cycles that operate over a range of timescales, including geologic, orbital (for example, Croll-Milankovitch cycles), seasonal and that of a single convective storm. In this Review Article, we describe the dominant exchange processes that operate over these timescales and present a post-Cassini view of Titan's methane-based hydrologic system.

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

Method and system to estimate variables in an integrated gasification combined cycle (IGCC) plant

Science.gov (United States)

Kumar, Aditya; Shi, Ruijie; Dokucu, Mustafa

2013-09-17

System and method to estimate variables in an integrated gasification combined cycle (IGCC) plant are provided. The system includes a sensor suite to measure respective plant input and output variables. An extended Kalman filter (EKF) receives sensed plant input variables and includes a dynamic model to generate a plurality of plant state estimates and a covariance matrix for the state estimates. A preemptive-constraining processor is configured to preemptively constrain the state estimates and covariance matrix to be free of constraint violations. A measurement-correction processor may be configured to correct constrained state estimates and a constrained covariance matrix based on processing of sensed plant output variables. The measurement-correction processor is coupled to update the dynamic model with corrected state estimates and a corrected covariance matrix. The updated dynamic model may be configured to estimate values for at least one plant variable not originally sensed by the sensor suite.

Comparison of PWR-IMF and FR fuel cycles

International Nuclear Information System (INIS)

Darilek, Petr; Zajac, Radoslav; Breza, Juraj; Necas, Vladimir

2007-01-01

The paper gives a comparison of PWR (Russia origin VVER-440) cycle with improved micro-heterogeneous inert matrix fuel assemblies and FR cycle. Micro-heterogeneous combined assembly contains transmutation pins with Pu and MAs from burned uranium reprocessing and standard uranium pins. Cycle analyses were performed by HELIOS spectral code and SCALE code system. Comparison is based on fuel cycle indicators, used in the project RED-IMPACT - part of EU FP6. Advantages of both closed cycles are pointed out. (authors)

Nuclear combined cycle gas turbines for variable electricity and heat using firebrick heat storage and low-carbon fuels

International Nuclear Information System (INIS)

Forsberg, Charles; Peterson, Per F.; McDaniel, Patrick; Bindra, Hitesh

2017-01-01

The world is transitioning to a low-carbon energy system. Variable electricity and industrial energy demands have been met with storable fossil fuels. The low-carbon energy sources (nuclear, wind and solar) are characterized by high-capital-costs and low-operating costs. High utilization is required to produce economic energy. Wind and solar are non-dispatchable; but, nuclear is the dispatchable energy source. Advanced combined cycle gas turbines with firebrick heat storage coupled to high-temperature reactors may enable economic variable electricity and heat production with constant full-power reactor output. Such systems efficiently couple to fluoride-salt-cooled high-temperature reactors (FHRs) with solid fuel and clean salt coolants, molten salt reactors (MSRs) with fuel dissolved in the salt coolant and salt-cooled fusion machines. Open Brayton combined cycles allow the use of natural gas, hydrogen, other fuels and firebrick heat storage for peak electricity production with incremental heat-to-electricity efficiencies from 66 to 70+% efficient. There are closed Brayton cycle options that use firebrick heat storage but these have not been investigated in any detail. Many of these cycles couple to high-temperature gas-cooled reactors (HTGRs). (author)

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

DEFF Research Database (Denmark)

Fantke, Peter; Jolliet, Olivier

2016-01-01

ions that involve burden shifting or that result in only incremental improvement. Focusing in the life cycle impacts on widely accepted and applied impact categories like global warming potential or cumulative energy demand aggregating several impact categories will lead to underestimations of life...... 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...... in a product. When combined chemical masses in products and further with toxicity information, this approach is a resourceful way to inform CAA and minimize human exposure to toxic chemicals in consumer products through both product use and environmental emissions. We use an example of chemicals in consumer...

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.

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.

Evaluation on the model of performance predictions for on-line monitoring system for combined-cycle power plant

International Nuclear Information System (INIS)

Kim, Si Moon

2002-01-01

This paper presents the simulation model developed to predict design and off-design performance of an actual combined cycle power plant(S-Station in Korea), which would be running combined with on-line performance monitoring system in an on-line real-time fashion. The first step in thermal performance analysis is to build an accurate performance model of the power plant, in order to achieve this goal, GateCycle program has been employed in developing the model. This developed models predict design and off-design performance with a precision of one percent over a wide range of operating conditions so that on-line real-time performance monitoring can accurately establish both current performance and expected performance and also help the operator identify problems before they would be noticed

Cell-cycle synchronisation of bloodstream forms of Trypanosoma brucei using Vybrant DyeCycle Violet-based sorting.

Science.gov (United States)

Kabani, Sarah; Waterfall, Martin; Matthews, Keith R

2010-01-01

Studies on the cell-cycle of Trypanosoma brucei have revealed several unusual characteristics that differ from the model eukaryotic organisms. However, the inability to isolate homogenous populations of parasites in distinct cell-cycle stages has limited the analysis of trypanosome cell division and complicated the understanding of mutant phenotypes with possible impact on cell-cycle related events. Although hydroxyurea-induced cell-cycle arrest in procyclic and bloodstream forms has been applied recently with success, such block-release protocols can complicate the analysis of cell-cycle regulated events and have the potential to disrupt important cell-cycle checkpoints. An alternative approach based on flow cytometry of parasites stained with Vybrant DyeCycle Orange circumvents this problem, but is restricted to procyclic form parasites. Here, we apply Vybrant Dyecycle Violet staining coupled with flow cytometry to effectively select different cell-cycle stages of bloodstream form trypanosomes. Moreover, the sorted parasites remain viable, although synchrony is rapidly lost. This method enables cell-cycle enrichment of populations of trypanosomes in their mammal infective stage, particularly at the G1 phase.

Power by waste heat recovery from low temperature industrial flue gas by Organic Flash Cycle (OFC) and transcritical-CO_2 power cycle: A comparative study through combined thermodynamic and economic analysis

International Nuclear Information System (INIS)

Mondal, Subha; De, Sudipta

2017-01-01

Both Organic flash cycle and transcritical CO_2 power cycle (T-CO_2 power cycle) allow cooling of hot flue gas stream to an appreciably lower temperature due to the absence of pinch limitation. In the present study, a combined thermodynamic and economic comparison is conducted between a T-CO_2 power cycle and Organic flash cycles using R-245fa and R600 as the working fluids. It is observed that work output per kg of flue gas flow rate is slightly higher for the T-CO_2 power cycle if the flue gas is allowed to cool to the corresponding lowest possible temperature in the Heat Recovery Unit (HRU). It is also observed that with maximum possible cooling of flue gas, minimum bare module costs (BMCs) for each kW power output of OFCs are somewhat higher compared to that of T-CO_2 power cycle. Minimum BMCs for each kW output of OFCs can be reduced substantially by increasing terminal temperature difference at the low temperature end of the HRU. However, the increasing terminal temperature difference at the low temperature end of the HRU is having negligible effect on BMC ($/kW) of T-CO_2 power cycle. - Highlights: • Combined thermodynamic and economic analysis done for T-CO_2 power cycle and OFC. • With highest heat recovery, T-CO_2 cycle produces slightly higher work output/kg of flue gas. • With highest heat recovery, minimum bare module costs in $/kW is slightly higher for OFCs. • Work outputs/kg of flue gas of all cycles are almost equal for these minimum BMCs. • BMCs in $/kW for OFCs sharply decrease with larger flue gas exit temperature.

A novel respiratory motion compensation strategy combining gated beam delivery and mean target position concept - A compromise between small safety margins and long duty cycles

International Nuclear Information System (INIS)

Guckenberger, Matthias; Kavanagh, Anthony; Webb, Steve; Brada, Michael

2011-01-01

Purpose: To evaluate a novel respiratory motion compensation strategy combining gated beam delivery with the mean target position (MTP) concept for pulmonary stereotactic body radiotherapy (SBRT). Materials and methods: Four motion compensation strategies were compared for 10 targets with motion amplitudes between 6 mm and 31 mm: the internal target volume concept (plan ITV ); the MTP concept where safety margins were adapted based on 4D dose accumulation (plan MTP ); gated beam delivery without margins for motion compensation (plan gated ); a novel approach combining gating and the MTP concept (plan gated and MTP ). Results: For 5/10 targets with an average motion amplitude of 9 mm, the differences in the mean lung dose (MLD) between plan gated and plan MTP were gated and MTP . Despite significantly shorter duty cycles, plan gated reduced the MLD by gated and MTP . The MLD was increased by 18% in plan MTP compared to that of plan gated and MTP . Conclusions: For pulmonary targets with motion amplitudes >10-15 mm, the combination of gating and the MTP concept allowed small safety margins with simultaneous long duty cycles.

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

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)

FCC-hh turn-around cycle

CERN Document Server

Alemany Fernandez, Reyes; Bartmann, Wolfgang; Buffat, Xavier; Niemi, Arto; Schulte, Daniel; Solfaroli Camillocci, Matteo; Stoel, Linda

2016-01-01

The turn-around cycle time of a collider is defined as the time spent between the end of stable beams and the start of the next stable beams period, and its calculation is of fundamental importance. On one side it is a crucial ingredient for the computation of the optimal time spent in luminosity production, which defines the integrated luminosity per fill or store. On the other side, combined with the availability and reliability of the machine, it allows to perform a detailed breakdown of the operational performance of the collider over an operational season, i.e. percentage of time in stable beams and beam in the machine with respect to down time. This paper presents a preliminary operational cycle definition for the hadron-hadron Future Circular Collider, as a base line for estimating the corresponding turn-around time. The cycle definition is based on the Large Hadron Collider (LHC) operational cycle. Two turn-around times are presented, the theoretical one and a more realistic one based on the LHC exper...

Comparative study of alternative ORC-based combined power systems to exploit high temperature waste heat

International Nuclear Information System (INIS)

Zhang, Chengyu; Shu, Gequn; Tian, Hua; Wei, Haiqiao; Liang, Xingyu

2015-01-01

Highlights: • Three ORC-based combined systems for ICE exhaust waste heat recovery are studied. • A parametric investigation is conducted under several typical engine conditions. • Performance is evaluated considering six thermodynamic, techno-economic indexes. • DORC distinguishes among other solutions for its highest energy recovery capacity. • TEG–ORC system becomes attractive when exhaust temperature is relatively low. - Abstract: In this paper, various combined power systems which regard organic Rankine cycle (ORC) as bottoming cycle to recover engine’s high temperature exhaust heat are proposed. The topping recovery cycle includes steam Rankine cycle (RC), Brayton cycle (BC) and thermoelectric generator (TEG). Comprehensive evaluations are conducted under five typical engine conditions, ranging from high load to low load, and system performance is assessed in terms of many thermodynamic indexes, such as net output power, thermal efficiency, recovery efficiency and exergy efficiency. Besides that, the irreversibility of each component is also discussed in detail. R123, R245fa and R600a for ORC system are considered to analyze the influence of working fluids. Considering the system techno-economy, the turbine size parameter (SP) and heat transfer capacity (UA) are chosen as key indicators. The results show that compared with the other two investigated approaches, dual-loop ORC (DORC) possesses the highest energy exploitation capacity under the whole operating region, with a 5.57% increase of fuel economy under the rated condition, but its values of SP and UA are large as well. TEG–ORC becomes appealing while under the relatively low load

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.

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.

Combination closed-cycle refrigerator/liquid-He4 cryostat for e- damage of bulk samples

International Nuclear Information System (INIS)

Johnson, E.C.

1987-01-01

A closed-cycle refrigerator/cryostat system for use in ultrasonic studies of electron irradiation damaged bulk specimens is described. The closed-cycle refrigerator provides a convenient means for long-term (several days) sample irradiation at low temperatures. A neon filled ''thermal diode'' is employed to permit efficient cooling, via liquid helium, of the sample below the base temperature of the refrigerator

Temporal fluxomics reveals oscillations in TCA cycle flux throughout the mammalian cell cycle.

Science.gov (United States)

Ahn, Eunyong; Kumar, Praveen; Mukha, Dzmitry; Tzur, Amit; Shlomi, Tomer

2017-11-06

Cellular metabolic demands change throughout the cell cycle. Nevertheless, a characterization of how metabolic fluxes adapt to the changing demands throughout the cell cycle is lacking. Here, we developed a temporal-fluxomics approach to derive a comprehensive and quantitative view of alterations in metabolic fluxes throughout the mammalian cell cycle. This is achieved by combining pulse-chase LC-MS-based isotope tracing in synchronized cell populations with computational deconvolution and metabolic flux modeling. We find that TCA cycle fluxes are rewired as cells progress through the cell cycle with complementary oscillations of glucose versus glutamine-derived fluxes: Oxidation of glucose-derived flux peaks in late G1 phase, while oxidative and reductive glutamine metabolism dominates S phase. These complementary flux oscillations maintain a constant production rate of reducing equivalents and oxidative phosphorylation flux throughout the cell cycle. The shift from glucose to glutamine oxidation in S phase plays an important role in cell cycle progression and cell proliferation. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

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.

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

Life cycle human health impacts of 875 pesticides

DEFF Research Database (Denmark)

Fantke, Peter; Jolliet, Oliver

2016-01-01

present a consistent framework for characterizing human toxicological impacts associated with pesticides applied to agricultural crops in the frame of life cycle impact assessment based on state-of-the-art data and methods. Methods We combine a dynamic multicrop plant uptake model designed for evaluating......-crop combinations of 10 orders of magnitude. Conclusions Our framework is operational for use in current life cycle impact assessment models, is made available for USEtox, and closes an important gap in the assessment of human exposure to pesticides. For ready use in life cycle assessment studies, we present...... pesticide-crop combination-specific characterization factors normalized to pesticide mass applied and provide default data for application times and loss due to post-harvest food processing. When using our data, we emphasize the need to consult current pesticide regulation, since each pesticide...

Preliminary Sizing Completed for Single- Stage-To-Orbit Launch Vehicles Powered By Rocket-Based Combined Cycle Technology

Science.gov (United States)

Roche, Joseph M.

2002-01-01

Single-stage-to-orbit (SSTO) propulsion remains an elusive goal for launch vehicles. The physics of the problem is leading developers to a search for higher propulsion performance than is available with all-rocket power. Rocket-based combined cycle (RBCC) technology provides additional propulsion performance that may enable SSTO flight. Structural efficiency is also a major driving force in enabling SSTO flight. Increases in performance with RBCC propulsion are offset with the added size of the propulsion system. Geometrical considerations must be exploited to minimize the weight. Integration of the propulsion system with the vehicle must be carefully planned such that aeroperformance is not degraded and the air-breathing performance is enhanced. Consequently, the vehicle's structural architecture becomes one with the propulsion system architecture. Geometrical considerations applied to the integrated vehicle lead to low drag and high structural and volumetric efficiency. Sizing of the SSTO launch vehicle (GTX) is itself an elusive task. The weight of the vehicle depends strongly on the propellant required to meet the mission requirements. Changes in propellant requirements result in changes in the size of the vehicle, which in turn, affect the weight of the vehicle and change the propellant requirements. An iterative approach is necessary to size the vehicle to meet the flight requirements. GTX Sizer was developed to do exactly this. The governing geometry was built into a spreadsheet model along with scaling relationships. The scaling laws attempt to maintain structural integrity as the vehicle size is changed. Key aerodynamic relationships are maintained as the vehicle size is changed. The closed weight and center of gravity are displayed graphically on a plot of the synthesized vehicle. In addition, comprehensive tabular data of the subsystem weights and centers of gravity are generated. The model has been verified for accuracy with finite element analysis. The

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.

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.

Self-organizing maps based on limit cycle attractors.

Science.gov (United States)

Huang, Di-Wei; Gentili, Rodolphe J; Reggia, James A

2015-03-01

Recent efforts to develop large-scale brain and neurocognitive architectures have paid relatively little attention to the use of self-organizing maps (SOMs). Part of the reason for this is that most conventional SOMs use a static encoding representation: each input pattern or sequence is effectively represented as a fixed point activation pattern in the map layer, something that is inconsistent with the rhythmic oscillatory activity observed in the brain. Here we develop and study an alternative encoding scheme that instead uses sparsely-coded limit cycles to represent external input patterns/sequences. We establish conditions under which learned limit cycle representations arise reliably and dominate the dynamics in a SOM. These limit cycles tend to be relatively unique for different inputs, robust to perturbations, and fairly insensitive to timing. In spite of the continually changing activity in the map layer when a limit cycle representation is used, map formation continues to occur reliably. In a two-SOM architecture where each SOM represents a different sensory modality, we also show that after learning, limit cycles in one SOM can correctly evoke corresponding limit cycles in the other, and thus there is the potential for multi-SOM systems using limit cycles to work effectively as hetero-associative memories. While the results presented here are only first steps, they establish the viability of SOM models based on limit cycle activity patterns, and suggest that such models merit further study. Copyright © 2014 Elsevier Ltd. All rights reserved.

Operating cycle optimization for a Magnus effect-based airborne wind energy system

International Nuclear Information System (INIS)

Milutinović, Milan; Čorić, Mirko; Deur, Joško

2015-01-01

Highlights: • Operating cycle of a Magnus effect-based AWE system has been optimized. • The cycle trajectory should be vertical and far from the ground based generator. • Vertical trajectory provides high pulling force that drives the generator. • Large distance from the generator is required for the feasibility of the cycle. - Abstract: The paper presents a control variables optimization study for an airborne wind energy production system. The system comprises an airborne module in the form of a buoyant, rotating cylinder, whose rotation in a wind stream induces the Magnus effect-based aerodynamic lift. Through a tether, the airborne module first drives the generator fixed on the ground, and then the generator becomes a motor that lowers the airborne module. The optimization is aimed at maximizing the average power produced at the generator during a continuously repeatable operating cycle. The control variables are the generator-side rope force and the cylinder rotation speed. The optimization is based on a multi-phase problem formulation, where operation is divided into ascending and descending phases, with free boundary conditions and free cycle duration. The presented simulation results show that significant power increase can be achieved by using the obtained optimal operating cycle instead of the initial, empirically based operation control strategy. A brief analysis is also given to provide a physical interpretation of the optimal cycle results

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

Classification Formula and Generation Algorithm of Cycle Decomposition Expression for Dihedral Groups

Directory of Open Access Journals (Sweden)

Dakun Zhang

2013-01-01

Full Text Available The necessary of classification research on common formula of group (dihedral group cycle decomposition expression is illustrated. It includes the reflection and rotation conversion, which derived six common formulae on cycle decomposition expressions of group; it designed the generation algorithm on the cycle decomposition expressions of group, which is based on the method of replacement conversion and the classification formula; algorithm analysis and the results of the process show that the generation algorithm which is based on the classification formula is outperformed by the general algorithm which is based on replacement conversion; it has great significance to solve the enumeration of the necklace combinational scheme, especially the structural problems of combinational scheme, by using group theory and computer.

Evaporative cycles - in theory and in practise

Energy Technology Data Exchange (ETDEWEB)

Rosen, P.M.

2000-08-01

The thesis is based on applied research, rather closed to industrial development. The developed simulation model, for pre-design of evaporative gas turbine cycles, has been validated in a 600 kW pilot plant and in rebuilt turbo-charged diesel engines. Besides of the work with the thesis including theoretical modelling and hardware development concerning wet cycles, the work has also resulted in three patents dealing with the technique studied. The main feature of the evaporative cycles is the way the integration between the gas and liquid flows is executed, combined with using low-level heat gathered into the liquid phase which is later used to evaporate the liquid itself in a humidification tower. In this tower, the mass- and heat transfer take place under stable physical laws, and if the tower is properly designed, the distilling effect in the tower will also be high. Today the combined cycle has the best thermal efficiency to generate electricity from fuels. Every new power cycle, including the evaporative cycles, will therefore be compared with power stations based on combined cycles. In evaporative cycles, the steam bottoming cycle of the combined cycles has been eliminated. Instead the 'steam' cycle is integrated into the gas cycle. This action has a favourable effect on thermal efficiency and on NO{sub x} formation in the combustion zone. The major part of this thesis is about the EvGT-project. At Lund University, the major objective of this project was to develop, design, erect and operate the world's first evaporative gas turbine unit. The objective was accomplished in 1999, and in the process of reaching the objective, rather large modelling errors, both thermodynamic and dimensioning of the humidification tower, have been detected in the open literature. It seems as if the pressure dependency of the humidification process has been underestimated in the models used today. The EvGT-pilot plant at Lund University was built and taken into

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

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

Improvement of CaO-based sorbent performance for CO{sub 2} looping cycles

Energy Technology Data Exchange (ETDEWEB)

Vasilije Manovic; Edward J. Anthony [CANMET Energy Technology Centre-Ottawa, Ottawa, ON (Canada)

2009-07-01

This paper presents research on CO{sub 2} capture by lime-based looping cycles. This is a new and promising technology that may help in mitigation of global warming and climate change caused primarily by the use of fossil fuels. The intensity of the anticipated changes urgently requires solutions such as the developing technologies for CO{sub 2} capture, especially those based on CaO looping cycles. This technology is at the pilot plant demonstration stage and there are still significant challenges that require solutions. The technology is based on a dual fluidized bed reactor which contains a carbonator - a unit for CO{sub 2} capture, and a calciner - a unit for CaO regeneration. The major technology components are well known from other technologies and easily applicable. However, even though CaO is a very good candidate as a solid CO{sub 2} carrier, its performance in a practical system still has significant limitations. Thus, research on CaO performance is critical and this paper discusses some of the more important problems and potential solutions that are being examined at CETC-O. To date, the most promising methods were reactivation of spent sorbent by steam, thermal pretreatment of sorbent, and doping, most likely with Al{sub 2}O{sub 3}. The combination of these methods, including pelletization, should provide us with enhanced sorbent performance. 75 refs., 19 figs.

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

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

-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......; 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...

Overall performance assessment of a combined cycle power plant: An exergo-economic analysis

International Nuclear Information System (INIS)

Sahin, Ahmet Z.; Al-Sharafi, Abdullah; Yilbas, Bekir S.; Khaliq, Abdul

2016-01-01

Highlights: • An exergo-economic analysis is carried out for a combined cycle power plant. • An overall performance index (OPI) is defined to analyze the power plant. • Four performance indicators and three scenarios are considered in the analysis. • The optimum configuration of the power plant differs for each scenarios considered. - Abstract: An exergo-economic analysis is carried out for a combined cycle power plant using the first law and the second law of thermodynamics, and the economic principles while incorporating GT PRO/PEACE Software Packages. An overall performance index (OPI) is defined to assess and analyze the optimum operational and design configurations of the power plant. Four performance indicators are considered for the analysis; namely, energy efficiency (ENE), exergy efficiency (EXE), levelized cost of electricity (COE), and the total investment (TI) cost. Three possible scenarios are considered in which different weight factor is assigned to the performance indicators when assessing the performance. These scenarios are: (i) the conventional case in which the levelized cost of electricity is given a high priority, (ii) environmental conscious case in which the exergy efficiency is given a high priority, and (iii) the economical case in which the total cost of investment is given a high priority. It is shown that the optimum size and the configuration of the power plant differ for each scenarios considered. The selection and optimization of the size and configuration of the power plant are found to be depending on the user priorities and the weight factors assigned to the performance indicators.

A Scramjet Compression System for Hypersonic Air Transportation Vehicle Combined Cycle Engines

Directory of Open Access Journals (Sweden)

Devendra Sen

2018-06-01

Full Text Available This paper proposes a compression system for a scramjet, to be used as part of a combined cycle engine on a hypersonic transport vehicle that can achieve sustained flight at 8 Mach 8. Initially research into scramjet compression system and shock wave interaction was conducted to establish the foundation of the scramjet inlet and isolator sections. A Computational Fluid Dynamics (CFD campaign was conducted, where the shock structure and flow characteristics was analysed between Mach 4.5–8. The compression system of a scramjet is of crucial importance in providing air at suitable Mach number, pressure and temperature to the combustion chamber. The use of turbojet engines in over-under configuration with the scramjet was investigated as well as the study of a combined cycle scramjet-ramjet configuration. It was identified that locating the scramjet in the centre with a rotated ramjet on either side, where its ramps make up the scramjet wall was the most optimal configuration, as it mitigated the effect of the oblique shocks propagating from the scramjet walls into the adjacent ramjet. Furthermore, this meant that the forebody of the vehicle could solely be used as the compression surface by the scramjet. In this paper, the sizing of the scramjet combustion chamber and nozzle were modified to match the flow properties of the oncoming flow with the purpose of producing the most optimum scramjet configuration for the cruise speed of Mach 8. CFD simulations showed that the scramjet inlet did not provide the levels of compression and stagnation pressure recovery initially required. However, it was found that the scramjet provided significantly more thrust than the drag of the aircraft at sustained Mach 8 flight, due to its utilisation of a very aerodynamic vehicle design.

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

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)

A thermodynamic study of waste heat recovery from GT-MHR using organic Rankine cycles

International Nuclear Information System (INIS)

Yari, Mortaza; Mahmoudi, S.M.S.

2011-01-01

This paper presents an investigation on the utilization of waste heat from a gas turbine-modular helium reactor (GT-MHR) using different arrangements of organic Rankine cycles (ORCs) for power production. The considered organic Rankine cycles were: simple organic Rankine cycle (SORC), ORC with internal heat exchanger (HORC) and regenerative organic Rankine cycle (RORC). The performances of the combined cycles were studied from the point of view of first and second-laws of thermodynamics. Individual models were developed for each component and the effects of some important parameters such as compressor pressure ratio, turbine inlet temperature, and evaporator and environment temperatures on the efficiencies and on the exergy destruction rate were studied. Finally the combined cycles were optimized thermodynamically using the EES (Engineering Equation Solver) software. Based on the identical operating conditions for the GT-MHR cycle, a comparison between the three combined cycles and a simple GT-MHR cycle is also were made. This comparison was also carried out from the point of view of economics. The GT-MHR/SORC combined cycle proved to be the best among all the cycles from the point of view of both thermodynamics and economics. The efficiency of this cycle was about 10% higher than that of GT-MHR alone. (orig.)

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

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

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%.

Turbine Based Combined/Combination Cycle/RTA Project Overview

Science.gov (United States)

Bartolotta, Paul A.; Quigley, Brian F.

2000-01-01

This viewgraph presentation gives an overview of the Revolutionary Turbine Accelerator (RTA) program. Details are given on the Single Stage To Orbit (SSTO) and Two Stage To Orbit (TSTO) aircraft, and the technological challenges associated with the RTA, SSTO, and TSTO.

Static and dynamic modelling of gas turbines in advanced cycles

Energy Technology Data Exchange (ETDEWEB)

Gustafsson, Jan-Olof

1998-12-01

Gas turbines have been in operation for at least 50 years. The engine is used for propulsion of aircraft and high speed ships. It is used for power production in remote locations and for peak load and emergency situations. Gas turbines have been used in combined cycles for 20 to 30 years. Highly efficient power plants based on gas turbines are a competitive option for the power industry today. The thermal efficiency of the simple cycle gas turbine has increased due to higher turbine inlet temperatures and improved compressor and expander designs. Equally important are the improved cycles in which the gas turbine operates. One example is the combined cycle that uses steam for turbine cooling. Steam is extracted from the bottoming cycle, then used as airfoil coolant in a closed loop and returned to the bottoming cycle. The Evaporative Gas Turbine (EvGT), also known as the Humid Air Turbine (HAT), is another advanced cycle. A mixture of air and water vapour is used as working media. Air from the compressor outlet is humidified and then preheated in a recuperator prior to combustion. The static and dynamic performance is changed when the gas turbine is introduced in an evaporative cycle. The cycle is gaining in popularity, but so far it has not been demonstrated. A Swedish joint program to develop the cycle has been in operation since 1993. As part of the program, a small pilot plant is being erected at the Lund Institute of Technology (LTH). The plant is based on a 600 kW gas turbine, and demonstration of the EvGT cycle started autumn 1998 and will continue, in the present phase, for one year. This thesis presents static and dynamic models for traditional gas turbine components, such as, the compressor, combustor, expander and recuperator. A static model for the humidifier is presented, based on common knowledge for atmospheric humidification. All models were developed for the pilot plant at LTH with the objective to support evaluation of the process and individual

Combined effects of scaffold stiffening and mechanical preconditioning cycles on construct biomechanics, gene expression, and tendon repair biomechanics.

Science.gov (United States)

Nirmalanandhan, Victor Sanjit; Juncosa-Melvin, Natalia; Shearn, Jason T; Boivin, Gregory P; Galloway, Marc T; Gooch, Cynthia; Bradica, Gino; Butler, David L

2009-08-01

Our group has previously reported that in vitro mechanical stimulation of tissue-engineered tendon constructs significantly increases both construct stiffness and the biomechanical properties of the repair tissue after surgery. When optimized using response surface methodology, our results indicate that a mechanical stimulus with three components (2.4% strain, 3000 cycles/day, and one cycle repetition) produced the highest in vitro linear stiffness. Such positive correlations between construct and repair stiffness after surgery suggest that enhancing structural stiffness before surgery could not only accelerate repair stiffness but also prevent premature failures in culture due to poor mechanical integrity. In this study, we examined the combined effects of scaffold crosslinking and subsequent mechanical stimulation on construct mechanics and biology. Autologous tissue-engineered constructs were created by seeding mesenchymal stem cells (MSCs) from 15 New Zealand white rabbits on type I collagen sponges that had undergone additional dehydrothermal crosslinking (termed ADHT in this manuscript). Both constructs from each rabbit were mechanically stimulated for 8h/day for 12 consecutive days with half receiving 100 cycles/day and the other half receiving 3000 cycles/day. These paired MSC-collagen autologous constructs were then implanted in bilateral full-thickness, full-length defects in the central third of rabbit patellar tendons. Increasing the number of in vitro cycles/day delivered to the ADHT constructs in culture produced no differences in stiffness or gene expression and no changes in biomechanical properties or histology 12 weeks after surgery. Compared to MSC-based repairs from a previous study that received no additional treatment in culture, ADHT crosslinking of the scaffolds actually lowered the 12-week repair stiffness. Thus, while ADHT crosslinking may initially stiffen a construct in culture, this specific treatment also appears to mask any benefits

A probability-based multi-cycle sorting method for 4D-MRI: A simulation study.

Science.gov (United States)

Liang, Xiao; Yin, Fang-Fang; Liu, Yilin; Cai, Jing

2016-12-01

To develop a novel probability-based sorting method capable of generating multiple breathing cycles of 4D-MRI images and to evaluate performance of this new method by comparing with conventional phase-based methods in terms of image quality and tumor motion measurement. Based on previous findings that breathing motion probability density function (PDF) of a single breathing cycle is dramatically different from true stabilized PDF that resulted from many breathing cycles, it is expected that a probability-based sorting method capable of generating multiple breathing cycles of 4D images may capture breathing variation information missing from conventional single-cycle sorting methods. The overall idea is to identify a few main breathing cycles (and their corresponding weightings) that can best represent the main breathing patterns of the patient and then reconstruct a set of 4D images for each of the identified main breathing cycles. This method is implemented in three steps: (1) The breathing signal is decomposed into individual breathing cycles, characterized by amplitude, and period; (2) individual breathing cycles are grouped based on amplitude and period to determine the main breathing cycles. If a group contains more than 10% of all breathing cycles in a breathing signal, it is determined as a main breathing pattern group and is represented by the average of individual breathing cycles in the group; (3) for each main breathing cycle, a set of 4D images is reconstructed using a result-driven sorting method adapted from our previous study. The probability-based sorting method was first tested on 26 patients' breathing signals to evaluate its feasibility of improving target motion PDF. The new method was subsequently tested for a sequential image acquisition scheme on the 4D digital extended cardiac torso (XCAT) phantom. Performance of the probability-based and conventional sorting methods was evaluated in terms of target volume precision and accuracy as measured

Implementing risk-informed life-cycle design

International Nuclear Information System (INIS)

Hill, Ralph S.

2009-01-01

This paper describes a design process based on risk-informed probabilistic design methodologies that cover a facility's life-cycle from start of conceptual design through decontamination and decommissioning. The concept embodies use of probabilistic risk assessments to establish target reliabilities for facility systems and components. The target reliabilities are used for system based code margin exchange and performance simulation analyses to optimize design over all phases (design, construction, operation and decommissioning) of a facility's life-cycle. System based code margin exchange reduces excessive level of construction margins for passive components to appropriate levels resulting in a more flexible structure of codes and standards that improves facility reliability and cost. System and subsystem simulation analyses determine the optimum combination of initial system and component construction reliability, maintenance frequency, and inspection frequency for both active and passive components. The paper includes a description of these risk-informed life-cycle design processes, a summary of work being done, and a discussion of additional work needed to implement the process.

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.

The epidermal cell kinetic response to ultraviolet B irradiation combines regenerative proliferation and carcinogen associated cell cycle delay

Energy Technology Data Exchange (ETDEWEB)

Olsen, W.M.; Kirkhus, B. (Oslo Univ. (Norway))

1989-09-01

The cell cycle traverse of epidermal basal cells 24 h after in vivo exposure of ultraviolet B (UVB) irradiation was studied by immunochemical staining of incorporated bromodeoxyuridine (BrdU) and bivariate BrdU/DNA flow cytometric analysis. The results were compared with the cell kinetic patterns following topical application of the skin carcinogen methylnitrosourea (MNU) as well as the skin irritant cantharidin. The cell cycle traverse in hairless mouse epidermis 24 h after in vivo exposure to UVB seemed to be a combination of the cell kinetic effects following chemical skin carcinogens and skin irritants. UVB irradiation induced both a delay in transit time through S phase, probably due to DNA damage and subsequent repair, as well as a reduction in the total cell cycle time consistent with rapid regenerative proliferation. (author).

Tunisia- British gas intends to participate to the building of a combined cycle electric power plant

International Nuclear Information System (INIS)

Anon.

1996-01-01

Here is described the project to build a combined-cycle power plant in Tunisia, project in which the British Gas is interested. The transport, distribution, import and export of electricity should be controlled by the Tunisian society of electricity and gas. In the context of an agreement with Gec-Alsthom, the british company hopes to offer to build, and exploit the future power plant. (N.C.)

Technical evaluation of biomass gasification technology integrated with combined cycle using bagasse as fuel; Avaliacao tecnica da tecnologia de gaseificacao de biomassa integrada a ciclos combinados utilizando bagaco como combustivel

Energy Technology Data Exchange (ETDEWEB)

Ortiz, Pablo Silva; Venturini, Osvaldo Jose; Lora, Electo Silva [Universidade Federal de Itajuba (NEST/UNIFEI), MG (Brazil). Nucleo de Excelencia em Geracao Termeletrica e Distribuida], email: pablo.silvaortiz@gmail.com; Campo, Andres Perez [Universidade Automona de Bucaramanga (UNAB) (Colombia). Fac. de Engenharia Fisico- Mecanica, Engenharia em Energia

2010-07-01

Biomass Integrated Gasification Combined Cycle (BIGCC) was identified as an advanced technology with potential to be competitive for electricity generation. The BIGCC technology uses biomass and the sub products of some industrial sectors processing, like sugar cane, as feedstock. The current Brazilian energy matrix is mainly based on renewable generation sources, making it important to assess these gasification technologies in the production of sugar, ethanol and electricity. In this work, a technical evaluation of the technologies incorporated in BIGCC power plants is done: the gasification process and the combined cycle power plant. On the other hand, the generated costs of these systems are analyzed, and the potential for implementation in Brazil plants from sugar cane bagasse is studied, in which a 10% increase in efficiency is obtained. (author)

Premenstrual dysphoric disorder symptom cluster improvement by cycle with the combined oral contraceptive ethinylestradiol 20 mcg plus drospirenone 3 mg administered in a 24/4 regimen.

Science.gov (United States)

Marr, Joachim; Niknian, Minoo; Shulman, Lee P; Lynen, Richard

2011-07-01

A combined oral contraceptive comprising ethinylestradiol (EE) 20 mcg/drospirenone 3 mg in a 24/4 regimen has been clinically shown to alleviate the symptoms associated with premenstrual dysphoric disorder (PMDD). However, previous studies did not report data according to cycle-by-cycle improvement. This was a subanalysis of a Phase III, double-blind, multicenter, United States-based study. Women with confirmed PMDD were randomized to EE 20 mcg/drospirenone 3 mg 24/4 or placebo for three treatment cycles. Ten of the 21 emotional and physical items on the Daily Record of Severity of Problems scale were grouped to define three symptom clusters: (a) negative emotions, (b) food cravings and (c) water retention-related symptoms. The change from baseline at each treatment cycle was compared between groups using a weighted analysis of covariance model. The full analysis set comprised 449 women. Daily Record of Severity of Problems scores for each symptom cluster were significantly reduced from baseline with both EE 20 mcg/drospirenone 3 mg 24/4 and placebo (pemotions, food cravings and water retention-related symptoms to a significantly greater extent than placebo during all three cycles of treatment. Copyright © 2011 Elsevier Inc. All rights reserved.

Development of Urban Driving Cycle with GPS Data Post Processing

Directory of Open Access Journals (Sweden)

Peter Lipar

2016-08-01

Full Text Available This paper presents GIS-based methodology for urban area driving cycle construction. The approach reaches beyond the frames of usual driving cycle development methods and takes into account another perspective of data collection. Rather than planning data collection, the approach is based on available in-vehicle measurement data post processing using Geographic Information Systems to manipulate the excessive database and extract only the representative and geographically limited individual trip data. With such data post processing the data was carefully adjusted to include only the data that describe representative driving in Ljubljana urban area. The selected method for the driving cycle development is based on searching for the best microtrips combination while minimizing the difference between two vectors; one based on generated cycle and the other on the database. Accounting for a large random sample of actual trip data, our approach enables more representative area-specific driving cycle development than the previously used techniques.

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.

Waste Classification based on Waste Form Heat Generation in Advanced Nuclear Fuel Cycles Using the Fuel-Cycle Integration and Tradeoffs (FIT) Model

Energy Technology Data Exchange (ETDEWEB)

Denia Djokic; Steven J. Piet; Layne F. Pincock; Nick R. Soelberg

2013-02-01

This study explores the impact of wastes generated from potential future fuel cycles and the issues presented by classifying these under current classification criteria, and discusses the possibility of a comprehensive and consistent characteristics-based classification framework based on new waste streams created from advanced fuel cycles. A static mass flow model, Fuel-Cycle Integration and Tradeoffs (FIT), was used to calculate the composition of waste streams resulting from different nuclear fuel cycle choices. This analysis focuses on the impact of waste form heat load on waste classification practices, although classifying by metrics of radiotoxicity, mass, and volume is also possible. The value of separation of heat-generating fission products and actinides in different fuel cycles is discussed. It was shown that the benefits of reducing the short-term fission-product heat load of waste destined for geologic disposal are neglected under the current source-based radioactive waste classification system , and that it is useful to classify waste streams based on how favorable the impact of interim storage is in increasing repository capacity.

Development of FBR cycle data base system

International Nuclear Information System (INIS)

Kubota, Sadae; Ohtaki, Akira; Hirao, Kazuhiro

2002-06-01

In the 'Feasibility Study on Commercialized Fast Reactor Cycle System (F/S)'. scenario evaluations, cost-benefit evaluations and system characteristic evaluations to show significance of the Fast Breeder Reactor (FBR) cycle system introduction concretely are performed in parallel with a design study for FBR plants, reprocessing systems and fabrication systems. In these evaluations, informations such as economic prospects, prospects for supply and demand of resources and a progress of engineering development are used in addition to design information. This report explains a FBR Cycle Database in order to carry out management and search of various design information and the relating information. The prototype system of the database was completed in the 2000 fiscal year, and the problem of the user number restriction of the prototype system has been improved by Web-ization in the 2001 fiscal year. About 7,000 data are stored in this data base (as of the end of March, 2002). The expansion of user etc., and the continuation of input work of various evaluation information will be carried out, in the phase 2 of F/S. (author)

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

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.

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.

A novel Carnot-based cycle for ocean thermal energy conversion

International Nuclear Information System (INIS)

Semmari, Hamza; Stitou, Driss; Mauran, Sylvain

2012-01-01

A thermodynamic engine cycle can be implemented by exploiting the temperature difference existing between the warm surface seawater and cold deep seawater. It employs a working fluid that evaporates by warm seawater, produces work in an expander device, such as a gas turbine and finally condenses by cold deep seawater. A new Carnot-based cycle for OTEC applications, called CAPILI cycle is presented. In this new engine cycle, work is produced by the movement of an inert liquid through a hydraulic turbine. This inert liquid characterized by a very low saturation pressure and immiscibility with the working fluid, acts as a liquid piston that moves alternately between two insulated cylinders. The insulated cylinders are connected alternately to an evaporator and a condenser, each of them operates at different pressure and temperature levels. A performance study which consists in a steady state energy balance is realised first to select the most suitable working fluid for this specific application. It was found that the best fluid is the HFC refrigerant R134a. A dynamic modelling based on the concept of equivalent Gibbs system is carried out to appreciate the dynamic behaviour and the performances of this new thermal conversion process. -- Highlights: ► A novel Carnot-based cycle operating with a liquid piston is investigated for OTEC application. ► The most suitable working fluid giving the best performances is found to be the HFC R134a. ► The performances of this new thermal process are evaluated using a dynamic modelling. ► A thermal efficiency of 1.9% can be obtained by exploiting seawater temperature difference of 20 °C. ► A net cycle efficiency of 1.2% is achieved considering a net to gross power production ratio of 61%.

Reprocessed and combined thorium fuel cycles in a PER system with a micro heterogeneous approaches

International Nuclear Information System (INIS)

Monteiro, Fabiana B.A.; Castro, Victor F.; Faria, Rochkhudson B. de; Pereira, Claubia; Fortini, Angela

2015-01-01

A micro heterogeneous approaches were used to study the behavior of reprocessed fuel spiked with thorium in a PWR fuel element considering (TRU-Th) cycle. The goal is to achieve a higher burnup using three different configurations to model the fuel element using SCALE 6.0. The reprocessed fuels were obtained using the ORIGEN 2.1 code from a spent PWR standard fuel (33,000 MWd/tHM burned), with 3.1% of initial enrichment. The spent fuel remained in the cooling pool for five years and then reprocessed using the UREX+ technique. Three configurations of micro heterogeneous approaches were analyzed, and the k inf and plutonium evolution during the burnup were evaluated. The preliminary results show that the behavior of advanced fuel based on transuranic elements spiked with thorium, and micro heterogeneous approach are satisfactory in PWRs, and the configuration that use a combination of Th and TRU (configuration 1) seems to be the most promising once has higher values for k inf during the burnup, compared with other configurations. (author)

Energy Approach-Based Simulation of Structural Materials High-Cycle Fatigue

Science.gov (United States)

Balayev, A. F.; Korolev, A. V.; Kochetkov, A. V.; Sklyarova, A. I.; Zakharov, O. V.

2016-02-01

The paper describes the mechanism of micro-cracks development in solid structural materials based on the theory of brittle fracture. A probability function of material cracks energy distribution is obtained using a probabilistic approach. The paper states energy conditions for cracks growth at material high-cycle loading. A formula allowing to calculate the amount of energy absorbed during the cracks growth is given. The paper proposes a high- cycle fatigue evaluation criterion allowing to determine the maximum permissible number of solid body loading cycles, at which micro-cracks start growing rapidly up to destruction.

A review on the use of gas and steam turbine combined cycles as prime movers for large ships. Part I: Background and design

International Nuclear Information System (INIS)

Haglind, Fredrik

2008-01-01

The aim of the present paper is to review the prospects of using combined cycles as prime movers for large ships, like, container ships, tankers and bulk carriers. The paper is divided into three parts of which this paper constitutes Part I. Here, the environmental and human health concerns of international shipping are outlined. The regulatory framework relevant for shipping and the design of combined cycles are discussed. In Part II, previous work and experience are reviewed, and an overview of the implications of introducing combined cycles as prime movers is included. In Part III, marine fuels are discussed and the pollutant emissions of gas turbines are compared with those of two-stroke, slow-speed diesel engines. Environmental effects of shipping include contributions to the formation of ground-level ozone, acidification, eutrophication and climate impact. Tightening environmental regulations limit the fuel sulphur content and pollutant emissions. For moderate live steam pressures, a vertical HRSG of drum-type mounted directly over the gas turbine, is suggested to be a viable configuration that minimizes ground floor and space requirements

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...

A signature-based method for indexing cell cycle phase distribution from microarray profiles

Directory of Open Access Journals (Sweden)

Mizuno Hideaki

2009-03-01

Full Text Available Abstract Background The cell cycle machinery interprets oncogenic signals and reflects the biology of cancers. To date, various methods for cell cycle phase estimation such as mitotic index, S phase fraction, and immunohistochemistry have provided valuable information on cancers (e.g. proliferation rate. However, those methods rely on one or few measurements and the scope of the information is limited. There is a need for more systematic cell cycle analysis methods. Results We developed a signature-based method for indexing cell cycle phase distribution from microarray profiles under consideration of cycling and non-cycling cells. A cell cycle signature masterset, composed of genes which express preferentially in cycling cells and in a cell cycle-regulated manner, was created to index the proportion of cycling cells in the sample. Cell cycle signature subsets, composed of genes whose expressions peak at specific stages of the cell cycle, were also created to index the proportion of cells in the corresponding stages. The method was validated using cell cycle datasets and quiescence-induced cell datasets. Analyses of a mouse tumor model dataset and human breast cancer datasets revealed variations in the proportion of cycling cells. When the influence of non-cycling cells was taken into account, "buried" cell cycle phase distributions were depicted that were oncogenic-event specific in the mouse tumor model dataset and were associated with patients' prognosis in the human breast cancer datasets. Conclusion The signature-based cell cycle analysis method presented in this report, would potentially be of value for cancer characterization and diagnostics.

Variable cycle control model for intersection based on multi-source information

Science.gov (United States)

Sun, Zhi-Yuan; Li, Yue; Qu, Wen-Cong; Chen, Yan-Yan

2018-05-01

In order to improve the efficiency of traffic control system in the era of big data, a new variable cycle control model based on multi-source information is presented for intersection in this paper. Firstly, with consideration of multi-source information, a unified framework based on cyber-physical system is proposed. Secondly, taking into account the variable length of cell, hysteresis phenomenon of traffic flow and the characteristics of lane group, a Lane group-based Cell Transmission Model is established to describe the physical properties of traffic flow under different traffic signal control schemes. Thirdly, the variable cycle control problem is abstracted into a bi-level programming model. The upper level model is put forward for cycle length optimization considering traffic capacity and delay. The lower level model is a dynamic signal control decision model based on fairness analysis. Then, a Hybrid Intelligent Optimization Algorithm is raised to solve the proposed model. Finally, a case study shows the efficiency and applicability of the proposed model and algorithm.

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

Study of mixtures based on hydrocarbons used in ORC (Organic Rankine Cycle) for engine waste heat recovery

International Nuclear Information System (INIS)

Shu, Gequn; Gao, Yuanyuan; Tian, Hua; Wei, Haiqiao; Liang, Xingyu

2014-01-01

For high temperature ORC (Organic Rankine Cycle) used in engine waste heat recovery, it's very critical to select a high temperature working fluid. HCs (Hydrocarbons) usually have excellent cycle performance, but the flammability limits their practical application. Considering that some retardants can be used to suppress flammability, the paper presents an application of mixtures based on hydrocarbons blending with refrigerant retardants to engine waste heat ORC. Three pure hydrocarbons (cyclopentane, cyclohexane, benzene) and two retardants (R11, R123) are selected for combination. Thermal efficiency and exergy loss are selected as the main objective functions. Based on thermodynamic model, the effects of retardants mass fraction, evaporation temperature and IHE (internal heat exchanger) are investigated. Results show that zeotropic mixtures do have higher thermal efficiency and lower exergy loss than pure fluids, at a certain mixture ratio. There exists the OMR (optimal mixture ratio) for different mixtures, and it changes with the evaporation temperature. When adding IHE to system, cycle performance could be obviously improved, and for benzene/R11 (0.7/0.3), the efficiency growth is about 7.12%∼9.72%. Using it, the maximum thermal efficiency of the system can achieve 16.7%, and minimum exergy loss is only 30.76 kW. - Highlights: • A theoretical analysis of Organic Rankine Cycle for engine exhaust heat recovery is proposed. • Mixtures based on hydrocarbons as working fluids have been suggested. • Effects of the IHE (internal heat exchanger) on ORC system are investigated. • OMR (Optimal mixture ratio) changes with the evaporation temperature. • Using the system, maximum thermal efficiency can achieve 16.7%

Ideal Point Design and Operation of CO2-Based Transcritical Rankine Cycle (CTRC System Based on High Utilization of Engine’s Waste Heats

Directory of Open Access Journals (Sweden)

Lingfeng Shi

2017-10-01

Full Text Available This research conducted a study specially to systematically analyze combined recovery of exhaust gas and engine coolant and related influence mechanism, including a detailed theoretical study and an assistant experimental study. In this research, CO2-based transcritical Rankine cycle (CTRC was used for fully combining the wastes heats. The main objective of theoretical research was to search an ‘ideal point’ of the recovery system and related influence mechanism, which was defined as operating condition of complete recovery of two waste heats. The theoretical methodology of this study could also provide a design reference for effective combined recovery of two or multiple waste heats in other fields. Based on a kW-class preheated CTRC prototype that was designed by the ‘ideal point’ method, an experimental study was conducted to verify combined utilization degree of two engine waste heats by the CTRC system. The operating results showed that the prototype can gain 44.4–49.8 kW and 22.7–26.7 kW heat absorption from exhaust gas and engine coolant, respectively. To direct practical operation, an experimental optimization work on the operating process was conducted for complete recovery of engine coolant exactly, which avoided deficient or excessive recovery.

Electromechanical conversion efficiency for dielectric elastomer generator in different energy harvesting cycles

Science.gov (United States)

Cao, Jian-Bo; E, Shi-Ju; Guo, Zhuang; Gao, Zhao; Luo, Han-Pin

2017-11-01

In order to improve electromechanical conversion efficiency for dielectric elastomer generators (DEG), on the base of studying DEG energy harvesting cycles of constant voltage, constant charge and constant electric field intensity, a new combined cycle mode and optimization theory in terms of the generating mechanism and electromechanical coupling process have been built. By controlling the switching point to achieve the best energy conversion cycle, the energy loss in the energy conversion process is reduced. DEG generating test bench which was used to carry out comparative experiments has been established. Experimental results show that the collected energy in constant voltage cycle, constant charge cycle and constant electric field intensity energy harvesting cycle decreases in turn. Due to the factors such as internal resistance losses, electrical losses and so on, actual energy values are less than the theoretical values. The electric energy conversion efficiency by combining constant electric field intensity cycle with constant charge cycle is larger than that of constant electric field intensity cycle. The relevant conclusions provide a basis for the further applications of DEG.

The nuclear fuel cycle versus the carbon cycle

International Nuclear Information System (INIS)

Ewing, R.C.

2005-01-01

Nuclear power provides approximately 17% of the world's electricity, which is equivalent to a reduction in carbon emissions of ∼0.5 gigatonnes (Gt) of C/yr. This is a modest reduction as compared with global emissions of carbon, ∼7 Gt C/yr. Most analyses suggest that in order to have a significant and timely impact on carbon emissions, carbon-free sources, such as nuclear power, would have to expand total production of energy by factors of three to ten by 2050. A three-fold increase in nuclear power capacity would result in a projected reduction in carbon emissions of 1 to 2 Gt C/yr, depending on the type of carbon-based energy source that is displaced. This three-fold increase utilizing present nuclear technologies would result in 25,000 metric tonnes (t) of spent nuclear fuel (SNF) per year, containing over 200 t of plutonium. This is compared to a present global inventory of approximately 280,000 t of SNF and >1,700 t of Pu. A nuclear weapon can be fashioned from as little as 5 kg of 239 Pu. However, there is considerable technological flexibility in the nuclear fuel cycle. There are three types of nuclear fuel cycles that might be utilized for the increased production of energy: open, closed, or a symbiotic combination of different types of reactor (such as, thermal and fast neutron reactors). The neutron energy spectrum has a significant effect on the fission product yield, and the consumption of long-lived actinides, by fission, is best achieved by fast neutrons. Within each cycle, the volume and composition of the high-level nuclear waste and fissile material depend on the type of nuclear fuel, the amount of burn-up, the extent of radionuclide separation during reprocessing, and the types of materials used to immobilize different radionuclides. As an example, a 232 Th-based fuel cycle can be used to breed fissile 233 U with minimum production of Pu. In this paper, I will contrast the production of excess carbon in the form of CO 2 from fossil fuels with

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

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.

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.

Release and sorption of alkali metals in coal fired combined cycle power systems; Freisetzung und Einbindung von Alkalimetallverbindungen in kohlebefeuerten Kombikraftwerken

Energy Technology Data Exchange (ETDEWEB)

Mueller, Michael

2009-07-01

Coal fired combined cycle power systems will be a sufficient way to increase the efficiency of coal combustion. However, combined cycle power systems require a reliable hot gas cleanup. Especially alkali metals, such as sodium and potassium, can lead to hot corrosion of the gas turbine blading if they condensate as sulphates. The actual work deals with the release and sorption of alkali metals in coal fired combined cycle power systems. The influence of coal composition, temperature and pressure on the release of alkali species in coal combustion was investigated and the relevant release mechanisms identified. Alumosilicate sorbents have been found that reduce the alkali concentration in the hot flue gas of the Circulating Pressurized Fluidized Bed Combustion 2{sup nd} Generation (CPFBC 2{sup nd} Gen.) at 750 C to values sufficient for use in a gas turbine. Accordingly, alumosilicate sorbents working at 1400 C have been found for the Pressurized Pulverized Coal Combustion (PPCC). The sorption mechanisms have been identified. Thermodynamic calculations were performed to upscale the results of the laboratory experiments to conditions prevailing in power systems. According to these calculations, there is no risk of hot corrosion in both processes. Furthermore, thermodynamic calculations were performed to investigate the behaviour of alkali metals in an IGCC with integrated hot gas cleanup and H{sub 2} membrane for CO{sub 2} sequestration. (orig.)

Energy and entropy analysis of closed adiabatic expansion based trilateral cycles

International Nuclear Information System (INIS)

Garcia, Ramon Ferreiro; Carril, Jose Carbia; Gomez, Javier Romero; Gomez, Manuel Romero

2016-01-01

Highlights: • The adiabatic expansion based TC surpass Carnot factor at low temperatures. • The fact of surpassing Carnot factor doesn’t violate the 2nd law. • An entropy analysis is applied to verify the fulfilment of the second law. • Correction of the exergy transfer associated with heat transferred to a cycle. - Abstract: A vast amount of heat energy is available at low cost within the range of medium and low temperatures. Existing thermal cycles cannot make efficient use of such available low grade heat because they are mainly based on conventional organic Rankine cycles which are limited by Carnot constraints. However, recent developments related to the performance of thermal cycles composed of closed processes have led to the exceeding of the Carnot factor. Consequently, once the viability of closed process based thermal cycles that surpass the Carnot factor operating at low and medium temperatures is globally accepted, research work will aim at looking into the consequences that lead from surpassing the Carnot factor while fulfilling the 2nd law, its impact on the 2nd law efficiency definition as well as the impact on the exergy transfer from thermal power sources to any heat consumer, including thermal cycles. The methodology used to meet the proposed objectives involves the analysis of energy and entropy on trilateral closed process based thermal cycles. Thus, such energy and entropy analysis is carried out upon non-condensing mode trilateral thermal cycles (TCs) characterised by the conversion of low grade heat into mechanical work undergoing closed adiabatic path functions: isochoric heat absorption, adiabatic heat to mechanical work conversion and isobaric heat rejection. Firstly, cycle energy analysis is performed to determine the range of some relevant cycle parameters, such as the operating temperatures and their associated pressures, entropies, internal energies and specific volumes. In this way, the ranges of temperatures within which

BWR fuel cycle optimization using neural networks

International Nuclear Information System (INIS)

Ortiz-Servin, Juan Jose; Castillo, Jose Alejandro; Pelta, David Alejandro

2011-01-01

Highlights: → OCONN a new system to optimize all nuclear fuel management steps in a coupled way. → OCON is based on an artificial recurrent neural network to find the best combination of partial solutions to each fuel management step. → OCONN works with a fuel lattices' stock, a fuel reloads' stock and a control rod patterns' stock, previously obtained with different heuristic techniques. → Results show OCONN is able to find good combinations according the global objective function. - Abstract: In nuclear fuel management activities for BWRs, four combinatorial optimization problems are solved: fuel lattice design, axial fuel bundle design, fuel reload design and control rod patterns design. Traditionally, these problems have been solved in separated ways due to their complexity and the required computational resources. In the specialized literature there are some attempts to solve fuel reloads and control rod patterns design or fuel lattice and axial fuel bundle design in a coupled way. In this paper, the system OCONN to solve all of these problems in a coupled way is shown. This system is based on an artificial recurrent neural network to find the best combination of partial solutions to each problem, in order to maximize a global objective function. The new system works with a fuel lattices' stock, a fuel reloads' stock and a control rod patterns' stock, previously obtained with different heuristic techniques. The system was tested to design an equilibrium cycle with a cycle length of 18 months. Results show that the new system is able to find good combinations. Cycle length is reached and safety parameters are fulfilled.

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...

Environmental flows and life cycle assessment of associated petroleum gas utilization via combined heat and power plants and heat boilers at oil fields

International Nuclear Information System (INIS)

Rajović, Vuk; Kiss, Ferenc; Maravić, Nikola; Bera, Oskar

2016-01-01

Highlights: • Environmental impact of associated petroleum gas flaring is discussed. • A modern trend of introducing cogeneration systems to the oil fields is presented. • Three alternative utilization options evaluated with life cycle assessment method. • Producing electricity and/or heat instead of flaring would reduce impacts. - Abstract: Flaring of associated petroleum gas is a major resource waste and causes considerable emissions of greenhouse gases and air pollutants. New environmental regulations are forcing oil industry to implement innovative and sustainable technologies in order to compete in growing energy market. A modern trend of introducing energy-effective cogeneration systems to the oil fields by replacing flaring and existing heat generation technologies powered by associated petroleum gas is discussed through material flow analysis and environmental impact assessment. The environmental assessment is based on the consequential life cycle assessment method and mainly primary data compiled directly from measurements on Serbian oil-fields or company-supplied information. The obtained results confirm that the utilization of associated petroleum gas via combined heat and power plants and heat boilers can provide a significant reduction in greenhouse gas emissions and resource depletion by displacing marginal production of heat and electricity. At the base case scenario, which assumes a 100% heat realization rate, the global warming potential of the combined heat and power plant and heat boiler scenarios were estimated at −4.94 and −0.54 kg CO_2_e_q Sm"−"3, whereas the cumulative fossil energy requirements of these scenarios were −48.7 and −2.1 MJ Sm"−"3, respectively. This is a significant reduction compared to the global warming potential (2.25 kg CO_2_e_q Sm"−"3) and cumulative fossil energy requirements (35.36 MJ Sm"−"3) of flaring. Nevertheless, sensitivity analyses have shown that life cycle assessment results are sensitive

Thorium-Based Fuel Cycles in the Modular High Temperature Reactor

Institute of Scientific and Technical Information of China (English)

CHANG Hong; YANG Yongwei; JING Xingqing; XU Yunlin

2006-01-01

Large stockpiles of civil-grade as well as weapons-grade plutonium have been accumulated in the world from nuclear power or other programs of different countries. One alternative for the management of the plutonium is to incinerate it in the high temperature reactor (HTR). The thorium-based fuel cycle was studied in the modular HTR to reduce weapons-grade plutonium stockpiles, while producing no additional plutonium or other transuranic elements. Three thorium-uranium fuel cycles were also investigated. The thorium absorption cross sections of the resolved and unresolved resonances were generated using the ZUT-DGL code based on existing resonance data. The equilibrium core of the modular HTR was calculated and analyzed by means of the code VSOP'94. The results show that the modular HTR can incinerate most of the initially loaded plutonium amounting to about 95.3% net 239Pu for weapons-grade plutonium and can effectively utilize the uranium and thorium in the thorium-uranium fuel cycles.

Estimates the Emission of Passenger Cars Based on the First Developed Driving Cycle in Nakhon Ratchasima Municipality, Thailand

Directory of Open Access Journals (Sweden)

Muangnak Noppatsorn

2017-01-01

Full Text Available This study aims to estimate emissions of passenger cars traveled on the highways in Nakhon Ratchasima Municipality (NRM based on recently developed driving cycles. A mobile phone application (SafeMate was used to record speed-time of passenger car on the highways both weekday and weekend. The results showed that the driving cycles of the passenger cars on highway 224 and 304 were quite different. More traffic congestion on highway 224 impacted the average speeds, ranging from 10 to 34 km/h with longer idling time. The average speeds on highway 304 ranged from 49 to 69 km/h with more cruise time. The combined driving cycles on both highways showed the average speeds of 20-40 km/h depending upon the time of days. The traffic density on weekday was higher than the weekend. Peak-hour weekday showed lower traffic flow than off-peak hour which was the opposite of the weekend. Based on the derived driving cycles, the passenger car traveled on the highways in NRM emitted CO, NOx and HC approximately 90.7-129.8, 25.5-34.5 and 6.9-11.7 tons/year, respectively. The passenger cars were estimated to emit about 13,927.7-20,419.3 tons/year of carbon dioxide on the highways. The highway 2 accounted more of the emissions due to the traffic volume and coverage distance in NRM.

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

Economic, energy and environmental evaluations of biomass-based fuel ethanol projects based on life cycle assessment and simulation

International Nuclear Information System (INIS)

Yu Suiran; Tao Jing

2009-01-01

This paper summarizes the research of Monte Carlo simulation-based Economic, Energy and Environmental (3E) Life Cycle Assessment (LCA) of the three Biomass-based Fuel Ethanol (BFE) projects in China. Our research includes both theoretical study and case study. In the theoretical study part, 3E LCA models are structured, 3E Index Functions are defined and the Monte Carlo simulation is introduced to address uncertainties in BFE life cycle analysis. In the case study part, projects of Wheat-based Fuel Ethanol (WFE) in Central China, Corn-based Fuel Ethanol (CFE) in Northeast China, and Cassava-based Fuel Ethanol (CFE) in Southwest China are evaluated from the aspects of economic viability and investment risks, energy efficiency and airborne emissions. The life cycle economy assessment shows that KFE project in Guangxi is viable, while CFE and WFE projects are not without government's subsidies. Energy efficiency assessment results show that WFE, CFE and KFE projects all have positive Net Energy Values. Emissions results show that the corn-based E10 (a blend of 10% gasoline and 90% ethanol by volume), wheat-based E10 and cassava-base E10 have less CO 2 and VOC life cycle emissions than conventional gasoline, but wheat-based E10 and cassava-based E10 can generate more emissions of CO, CH 4 , N 2 O, NO x , SO 2 , PM 10 and corn-based E10 can has more emissions of CH 4 , N 2 O, NO x , SO, PM 10 .

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.

Life cycle analysis of distributed concentrating solar combined heat and power: economics, global warming potential and water

International Nuclear Information System (INIS)

Norwood, Zack; Kammen, Daniel

2012-01-01

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 gCO 2 eq kWh −1 of electricity and ∼10 gCO 2 eq 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. (letter)

Thermodynamic and economic studies of two new high efficient power-cooling cogeneration systems based on Kalina and absorption refrigeration cycles

International Nuclear Information System (INIS)

Rashidi, Jouan; Ifaei, Pouya; Esfahani, Iman Janghorban; Ataei, Abtin; Yoo, Chang Kyoo

2016-01-01

Highlights: • Proposing two new power and cooling cogeneration systems based on absorption chillers and Kalina cycles. • Model-based comparison through thermodynamic and economic standpoints. • Investigating sensitivity of system performance and costs to the key parameters. • Reducing total annual costs of the base system up to 8% by cogeneration. • Increasing thermal efficiency up to 4.9% despite of cooling generation. - Abstract: Two new power and cooling cogeneration systems based on Kalina cycle (KC) and absorption refrigeration cycle (AC) are proposed and studied from thermodynamic and economic viewpoints. The first proposed system, Kalina power-cooling cycle (KPCC), combines the refrigerant loop of the water-ammonia absorption chiller, consisting of an evaporator and two throttling valves with the KC. A portion of the KC mass flow enters the evaporator to generate cooling after being condensed in the KPCC system. KPCC is a flexible system adapting power and cooling cogeneration to the demand. The second proposed system, Kalina lithium bromide absorption chiller cycle (KLACC), consists of the KC and a single effect lithium bromide-water absorption chiller (AC_L_i_B_r_-_w_a_t_e_r). The KC subsystem discharges heat to the AC_L_i_B_r_-_w_a_t_e_r desorber before condensing in the condenser. The performance and economic aspects of both proposed systems are analyzed and compared with the stand alone KC. A parametric analysis is conducted to evaluate the sensitivity of efficiencies and the generated power and cooling quantities to the key operating variables. The results showed that, thermal efficiency and total annual costs decreased by 5.6% and 8% for KPCC system but increased 4.9% and 58% for KLACC system, respectively. Since the power-cooling efficiency of KLACC is 42% higher than KPCC it can be applied where the aim is cooling generation without considering economic aspects.

Core concept for long operating cycle simplified BWR (LSBWR)

International Nuclear Information System (INIS)

Kouji, Hiraiwa; Noriyuki, Yoshida; Mikihide, Nakamaru; Hideaki, Heki; Masanori, Aritomi

2002-01-01

An innovative core concept for a long operating cycle simplified BWR (LSBWR) is currently being developed under a Toshiba Corporation and Tokyo Institute of Technology joint study. In this core concept, the combination of enriched uranium oxide fuels and loose-pitched lattice is adopted for an easy application of natural circulation. A combination of enriched gadolinium and 0.7-times sized small bundle with peripheral-positioned gadolinium rod is also adopted as a key design concept for 15-year cycle operation. Based on three-dimensional nuclear and thermal hydraulic calculation, a nuclear design for fuel bundle has been determined. Core performance has been evaluated based on this bundle design and shows that thermal performance and reactivity characteristics meet core design criteria. Additionally, a control rod operation plan for an extension of control rod life has been successfully determined. (author)

Using neuro-fuzzy based method to develop nuclear turbine cycle model

International Nuclear Information System (INIS)

Chan Yeakuang; Chang Chinjang

2009-01-01

The purpose of this study is to describe a hybrid soft-computing modeling technique used to develop the steam turbine cycle model for nuclear power plants. The technique uses neuro-fuzzy model to predict the generator output. Firstly, the plant past three fuel cycles operating data above 95% load were collected and validated as the baseline performance data set. Then the signal errors for new operating data were detected by comparison with the baseline data set and their allowable range of variations. Finally, the most important parameters were selected as an input of the neuro-fuzzy based steam turbine cycle model. After training and testing with key parameters (i.e. throttle pressure, condenser backpressure, feedwater flow rate, and final feedwater temperature), the proposed model can be used to predict the generator output. The analysis results show this neuro-fuzzy based turbine cycle model can be used to predict the generator output with a good agreement. Moreover, the achievement of this study provides an alternative approach in thermal performance evaluation for nuclear power plants. (author)

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

Nitrogen expander cycles for large capacity liquefaction of natural gas

Energy Technology Data Exchange (ETDEWEB)

Chang, Ho-Myung; Park, Jae Hoon; Gwak, Kyung Hyun [Hong Ik University, Department of Mechanical Engineering, Seoul, 121-791 (Korea, Republic of); Choe, Kun Hyung [Korea Gas Corporation, Incheon, 406-130 (Korea, Republic of)

2014-01-29

Thermodynamic study is performed on nitrogen expander cycles for large capacity liquefaction of natural gas. In order to substantially increase the capacity, a Brayton refrigeration cycle with nitrogen expander was recently added to the cold end of the reputable propane pre-cooled mixed-refrigerant (C3-MR) process. Similar modifications with a nitrogen expander cycle are extensively investigated on a variety of cycle configurations. The existing and modified cycles are simulated with commercial process software (Aspen HYSYS) based on selected specifications. The results are compared in terms of thermodynamic efficiency, liquefaction capacity, and estimated size of heat exchangers. The combination of C3-MR with partial regeneration and pre-cooling of nitrogen expander cycle is recommended to have a great potential for high efficiency and large capacity.

Nitrogen expander cycles for large capacity liquefaction of natural gas

Science.gov (United States)

Chang, Ho-Myung; Park, Jae Hoon; Gwak, Kyung Hyun; Choe, Kun Hyung

2014-01-01

Thermodynamic study is performed on nitrogen expander cycles for large capacity liquefaction of natural gas. In order to substantially increase the capacity, a Brayton refrigeration cycle with nitrogen expander was recently added to the cold end of the reputable propane pre-cooled mixed-refrigerant (C3-MR) process. Similar modifications with a nitrogen expander cycle are extensively investigated on a variety of cycle configurations. The existing and modified cycles are simulated with commercial process software (Aspen HYSYS) based on selected specifications. The results are compared in terms of thermodynamic efficiency, liquefaction capacity, and estimated size of heat exchangers. The combination of C3-MR with partial regeneration and pre-cooling of nitrogen expander cycle is recommended to have a great potential for high efficiency and large capacity.

Nitrogen expander cycles for large capacity liquefaction of natural gas

International Nuclear Information System (INIS)

Chang, Ho-Myung; Park, Jae Hoon; Gwak, Kyung Hyun; Choe, Kun Hyung

2014-01-01

Thermodynamic study is performed on nitrogen expander cycles for large capacity liquefaction of natural gas. In order to substantially increase the capacity, a Brayton refrigeration cycle with nitrogen expander was recently added to the cold end of the reputable propane pre-cooled mixed-refrigerant (C3-MR) process. Similar modifications with a nitrogen expander cycle are extensively investigated on a variety of cycle configurations. The existing and modified cycles are simulated with commercial process software (Aspen HYSYS) based on selected specifications. The results are compared in terms of thermodynamic efficiency, liquefaction capacity, and estimated size of heat exchangers. The combination of C3-MR with partial regeneration and pre-cooling of nitrogen expander cycle is recommended to have a great potential for high efficiency and large capacity