Reactor design, cold-model experiment and CFD modeling for chemical looping combustion

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shaohua; Ma, Jinchen; Hu, Xintao; Zhao, Haibo; Wang, Baowen; Zheng, Chuguang [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion

2013-07-01

Chemical looping combustion (CLC) is an efficient, clean and cheap technology for CO{sub 2} capture, and an interconnected fluidized bed is more appropriate solution for CLC. This paper aims to design a reactor system for CLC, carry out cold-model experiment of the system, and model fuel reactor using commercial CFD software. As for the CLC system, the air reactor (AR) is designed as a fast fluidized bed while the fuel reactor (FR) is a bubbling bed; a cyclone is used for solid separation of the AR exit flow. The AR and FR are separated by two U-type loop seals to remain gas sealed. Considered the chemical kinetics of oxygen carrier, fluid dynamics, pressure balance and mass balance of the system simultaneously, some key design parameters of a CH{sub 4}-fueled and Fe{sub 2}O{sub 3}/Al{sub 2}O{sub 3}-based CLC reactor (thermal power of 50 kWth) are determined, including key geometric parameters (reactor cross-sectional area and reactor height) and operation parameters (bed material quantity, solid circulation rate, apparent gas velocity of each reactor). A cold-model bench having same geometric parameters with its prototype is built up to study the effects of various operation conditions (including gas velocity in the reactors and loop seals, and bed material height, etc.) on the solids circulation rate, gas leakage, and pressure balance. It is witnessed the cold-model system is able to meet special requirements for CLC system such as gas sealing between AR and FR, the circulation rate and particles residence time. Furthermore, the thermal FR reactor with oxygen carrier of Fe{sub 2}O{sub 3}/Al{sub 2}O{sub 3} and fuel of CH{sub 4} is simulated by commercial CFD solver FLUENT. It is found that for the design case the combustion efficiency of CH{sub 4} reaches 88.2%. A few part of methane is unburned due to fast, large bubbles rising through the reactor.

Thermal and mechanical behaviour of oxygen carrier materials for chemical looping combustion in a packed bed reactor

NARCIS (Netherlands)

Jacobs, M.; Van Noyen, J.; Larring, Y.; McCann, M.; Pishahang, M.; Amini, S.; Ortiz, M.; Galluci, F.; Sint-Annaland, M. V.; Tournigant, D.; Louradour, E.; Snijkers, F.

2015-01-01

Chemical looping combustion (CLC) is a promising carbon capture technology where cyclic reduction and oxidation of a metallic oxide, which acts as a solid oxygen carrier, takes place. With this system, direct contact between air and fuel can be avoided, and so, a concentrated CO2 stream is generated

CFD analysis of bubble hydrodynamics in a fuel reactor for a hydrogen-fueled chemical looping combustion system

International Nuclear Information System (INIS)

Harichandan, Atal Bihari; Shamim, Tariq

2014-01-01

Highlights: • Computational study of the fuel reactor of chemical looping combustion technology. • The results yield better understanding of the bubble hydrodynamics in fuel reactor. • Increasing the reactor bed length increases the conversion rate. • Small oxygen carrier particles improves the conversion rate. - Abstract: This study investigates the temporal development of bubble hydrodynamics in the fuel reactor of a hydrogen-fueled chemical looping combustion (CLC) system by using a computational model. The model also investigates the molar fraction of products in gas and solid phases. The study assists in developing a better understanding of the CLC process, which has many advantages such as being a potentially promising candidate for an efficient carbon dioxide capture technology. The study employs the kinetic theory of granular flow. The reactive fluid dynamic system of the fuel reactor is customized by incorporating the kinetics of an oxygen carrier reduction into a commercial computational fluid dynamics (CFD) code. An Eulerian multiphase treatment is used to describe the continuum two-fluid model for both gas and solid phases. CaSO 4 and H 2 are used as an oxygen carrier and a fuel, respectively. The computational results are validated with the experimental and numerical results available in the open literature. The CFD simulations are found to capture the features of the bubble formation, rise and burst in unsteady and quasi-steady states very well. The results show a significant increase in the conversion rate with higher dense bed height, lower bed width, higher free board height and smaller oxygen carrier particles which upsurge an overall performance of the CLC plant

Simulation and validation of chemical-looping combustion using ASPEN plus

Energy Technology Data Exchange (ETDEWEB)

Zhou, Ling [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States); Zhang, Zheming; Agarwal, Ramesh K. [Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States)

2013-07-01

Laboratory-scale experimental studies have demonstrated that Chemical-Looping Combustion (CLC) is an advanced technology which holds great potential for high-efficiency low-cost carbon capture. The generated syngas in CLC is subsequently oxidized to CO2 and H2O by reaction with an oxygen carrier. In this paper, process-level models of CLC are established in ASPEN Plus code for detailed simulations. The entire CLC process, from the beginning of coal gasification to reduction and oxidation of the oxygen carrier is modeled. The heat content of each major component such as fuel and air reactors and air/flue gas heat exchangers is carefully examined. Large amount of energy is produced in the fuel reactor, but energy needs to be supplied to the air reactor. The overall performance and efficiency of the modeled CLC systems are also evaluated.

Chemical looping reactor system design double loop circulating fluidized bed (DLCFB)

Energy Technology Data Exchange (ETDEWEB)

Bischi, Aldo

2012-05-15

Chemical looping combustion (CLC) is continuously gaining more importance among the carbon capture and storage (CCS) technologies. It is an unmixed combustion process which takes place in two steps. An effective way to realize CLC is to use two interconnected fluidized beds and a metallic powder circulating among them, acting as oxygen carrier. The metallic powder oxidizes at high temperature in one of the two reactors, the air reactor (AR). It reacts in a highly exothermic reaction with the oxygen of the injected fluidising air. Afterwards the particles are sent to the other reactor where the fuel is injected, the fuel reactor (FR). There, they transport heat and oxygen necessary for the reaction with the injected fuel to take place. At high temperatures, the particle's oxygen reacts with the fuel producing Co2 and steam, and the particles are ready to start the loop again. The overall reaction, the sum of the enthalpy changes of the oxygen carrier oxidation and reduction reactions, is the same as for the conventional combustion. Two are the key features, which make CLC promising both for costs and capture efficiency. First, the high inherent irreversibility of the conventional combustion is avoided because the energy is utilized stepwise. Second, the Co2 is intrinsically separated within the process; so there is in principle no need either of extra carbon capture devices or of expensive air separation units to produce oxygen for oxy-combustion. A lot of effort is taking place worldwide on the development of new chemical looping oxygen carrier particles, reactor systems and processes. The current work is focused on the reactor system: a new design is presented, for the construction of an atmospheric 150kWth prototype working with gaseous fuel and possibly with inexpensive oxygen carriers derived from industrial by-products or natural minerals. It consists of two circulating fluidized beds capable to operate in fast fluidization regime; this will increase the

Natural Ores as Oxygen Carriers in Chemical Looping Combustion

Energy Technology Data Exchange (ETDEWEB)

Tian, Hanjing; Siriwardane, Ranjani; Simonyi, Thomas; Poston, James

2013-08-01

Chemical looping combustion (CLC) is a combustion technology that utilizes oxygen from oxygen carriers (OC), such as metal oxides, instead of air to combust fuels. The use of natural minerals as oxygen carriers has advantages, such as lower cost and availability. Eight materials, based on copper or iron oxides, were selected for screening tests of CLC processes using coal and methane as fuels. Thermogravimetric experiments and bench-scale fixed-bed reactor tests were conducted to investigate the oxygen transfer capacity, reaction kinetics, and stability during cyclic reduction/oxidation reaction. Most natural minerals showed lower combustion capacity than pure CuO/Fe{sub 2}O{sub 3} due to low-concentrations of active oxide species in minerals. In coal CLC, chryscolla (Cu-based), magnetite, and limonite (Fe-based) demonstrated better reaction performances than other materials. The addition of steam improved the coal CLC performance when using natural ores because of the steam gasification of coal and the subsequent reaction of gaseous fuels with active oxide species in the natural ores. In methane CLC, chryscolla, hematite, and limonite demonstrated excellent reactivity and stability in 50-cycle thermogravimetric analysis tests. Fe{sub 2}O{sub 3}-based ores possess greater oxygen utilization but require an activation period before achieving full performance in methane CLC. Particle agglomeration issues associated with the application of natural ores in CLC processes were also studied by scanning electron microscopy (SEM).

Alstom's Chemical Looping Combustion Prototype for CO₂ Capture from Existing Pulverized Coal-Fired Power Plants

Energy Technology Data Exchange (ETDEWEB)

Andrus, Jr., Herbert E. [Alstom Power Inc., Windsor, CT (United States); Chiu, John H. [Alstom Power Inc., Windsor, CT (United States); Edberg, Carl D. [Alstom Power Inc., Windsor, CT (United States); Thibeault, Paul R. [Alstom Power Inc., Windsor, CT (United States); Turek, David G. [Alstom Power Inc., Windsor, CT (United States)

2012-09-30

Alstom’s Limestone Chemical Looping (LCL™) process has the potential to capture CO₂ from new and existing coal-fired power plants while maintaining high plant power generation efficiency. This new power plant concept is based on a hybrid combustion- gasification process utilizing high temperature chemical and thermal looping technology. This process could also be potentially configured as a hybrid combustion-gasification process producing a syngas or hydrogen for various applications while also producing a separate stream of CO₂ for use or sequestration. The targets set for this technology is to capture over 90% of the total carbon in the coal at cost of electricity which is less than 20% greater than Conventional PC or CFB units. Previous work with bench scale test and a 65 kWt Process Development Unit Development (PDU) has validated the chemistry required for the chemical looping process and provided for the investigation of the solids transport mechanisms and design requirements. The objective of this project is to continue development of the combustion option of chemical looping (LCL-C™) by designing, building and testing a 3 MWt prototype facility. The prototype includes all of the equipment that is required to operate the chemical looping plant in a fully integrated manner with all major systems in service. Data from the design, construction, and testing will be used to characterize environmental performance, identify and address technical risks, reassess commercial plant economics, and develop design information for a demonstration plant planned to follow the proposed Prototype. A cold flow model of the prototype will be used to predict operating conditions for the prototype and help in operator training. Operation of the prototype will provide operator experience with this new technology and performance data of the LCL-C™ process, which will be applied to the commercial design and economics and plan for a future demonstration

Study of dimensional changes during redox cycling of oxygen carrier materials for chemical looping combustion

NARCIS (Netherlands)

Fossdal, A.; Darell, O.; Lambert, A.; Schols, E.; Comte, E.; Leenman, R.N.; Blom, R.

2015-01-01

Dimensional and phase changes of four candidate oxygen carrier materials for chemical looping combustion are investigated by dilatometry and high-temperature X-ray diffraction during four redox cycles. NiO/Ni2AlO4 does not exhibit significant dimensional changes during cycling, and it is shown that

Computational fluid dynamics simulation for chemical looping combustion of coal in a dual circulation fluidized bed

International Nuclear Information System (INIS)

Su, Mingze; Zhao, Haibo; Ma, Jinchen

2015-01-01

Highlights: • CFD simulation of a 5 kW_t_h CLC reactor of coal was conducted. • Gas leakage, flow pattern and combustion efficiency of the reactor was analyzed. • Optimal condition was achieved based on operation characteristics understanding. - Abstract: A dual circulation fluidized bed system is widely accepted for chemical looping combustion (CLC) for enriching CO_2 from the utilization of fossil fuels. Due to the limitations of the measurement, the details of multiphase reactive flows in the interconnected fluidized bed reactors are difficult to obtain. Computational Fluid Dynamics (CFD) simulation provides a promising method to understand the hydrodynamics, chemical reaction, and heat and mass transfers in CLC reactors, which are very important for the rational design, optimal operation, and scaling-up of the CLC system. In this work, a 5 kW_t_h coal-fired CLC dual circulation fluidized bed system, which was developed by our research group, was first simulated for understanding gas leakage, flow pattern and combustion efficiency. The simulation results achieved good agreement with the experimental measurements, which validates the simulation model. Subsequently, to improve the combustion efficiency, a new operation condition was simulated by increasing the reactor temperature and decreasing the coal feeding. An improvement in the combustion efficiency was attained, and the simulation results for the new operation condition were also validated by the experimental measurements in the same CLC combustor. All of the above processes demonstrated the validity and usefulness of the simulation results to improve the CLC reactor operation.

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

Directory of Open Access Journals (Sweden)

Álvaro Urdiales Montesino

2016-08-01

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

Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

KAUST Repository

Zhao, Zhenlong; Chen, Tianjiao; Ghoniem, Ahmed F.

2013-01-01

Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two

Thermodynamic analysis of in situ gasification-chemical looping combustion (iG-CLC) of Indian coal.

Science.gov (United States)

Suresh, P V; Menon, Kavitha G; Prakash, K S; Prudhvi, S; Anudeep, A

2016-10-01

Chemical looping combustion (CLC) is an inherent CO 2 capture technology. It is gaining much interest in recent years mainly because of its potential in addressing climate change problems associated with CO 2 emissions from power plants. A typical chemical looping combustion unit consists of two reactors-fuel reactor, where oxidation of fuel occurs with the help of oxygen available in the form of metal oxides and, air reactor, where the reduced metal oxides are regenerated by the inflow of air. These oxides are then sent back to the fuel reactor and the cycle continues. The product gas from the fuel reactor contains a concentrated stream of CO 2 which can be readily stored in various forms or used for any other applications. This unique feature of inherent CO 2 capture makes the technology more promising to combat the global climate changes. Various types of CLC units have been discussed in literature depending on the type of fuel burnt. For solid fuel combustion three main varieties of CLC units exist namely: syngas CLC, in situ gasification-CLC (iG-CLC) and chemical looping with oxygen uncoupling (CLOU). In this paper, theoretical studies on the iG-CLC unit burning Indian coal are presented. Gibbs free energy minimization technique is employed to determine the composition of flue gas and oxygen carrier of an iG-CLC unit using Fe 2 O 3 , CuO, and mixed carrier-Fe 2 O 3 and CuO as oxygen carriers. The effect of temperature, suitability of oxygen carriers, and oxygen carrier circulation rate on the performance of a CLC unit for Indian coal are studied and presented. These results are analyzed in order to foresee the operating conditions at which economic and smooth operation of the unit is expected.

CaMn0.875Ti0.125O3 as oxygen carrier for chemical-looping combustion with oxygen uncoupling (CLOU)—Experiments in a continuously operating fluidized-bed reactor system

KAUST Repository

Rydé n, Magnus; Lyngfelt, Anders; Mattisson, Tobias

2011-01-01

Particles of the perovskite material CaMn0.875Ti0.125O3 has been examined as oxygen carrier for chemical-looping with oxygen uncoupling, and for chemical-looping combustion of natural gas, by 70h of experiments in a circulating fluidized-bed reactor

Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 2: Base Case and Sensitivity Analysis

KAUST Repository

Zhao, Zhenlong; Chen, Tianjiao; Ghoniem, Ahmed F.

2013-01-01

Part 1 (10.1021/ef3014103) of this series describes a new rotary reactor for gas-fueled chemical-looping combustion (CLC), in which, a solid wheel with microchannels rotates between the reducing and oxidizing streams. The oxygen carrier (OC) coated

Performance of calcium manganate as oxygen carrier in chemical looping combustion of biochar in a 10 kW pilot

International Nuclear Information System (INIS)

Schmitz, Matthias; Linderholm, Carl Johan

2016-01-01

Highlights: • A manganese-based perovskite material was used as oxygen carrier in chemical looping combustion. • The oxygen carrier’s performance was superior to materials previously tested in this reactor throughout the testing period. • Under stable conditions, oxygen demand was as low as 2.1% with a carbon capture efficiency of up to 98%. • No signs of agglomeration were detected. • Gaseous oxygen was released at all relevant fuel reactor temperatures. - Abstract: Chemical looping combustion (CLC) and chemical looping with oxygen uncoupling (CLOU) are carbon capture technologies which achieve gas separation by means of cycling oxidation and reduction of a solid oxygen carrier. In this study, the performance and CLOU properties of an oxygen carrier with perovskite structure, CaMn_0_._9Mg_0_._1O_3_−_δ_, were investigated in a 10 kW pilot. The fuel consisted of biochar with very low sulphur content. Around 37 h of operation with fuel were carried out in the 10 kW chemical looping combustor. Previous operational experience in this unit has been achieved using different natural minerals as oxygen carrier – mainly ilmenite and manganese ore. Parametric studies performed in this work included variation of fuel flow, solids circulation rate, temperature and fluidization gas in the fuel reactor. The oxygen carrier was exposed to a total 73 h of hot fluidization (T > 600 °C). No hard particle agglomerations were formed during the experiments. An oxygen demand as low as 2.1% could be reached under stable operating conditions, with a carbon capture efficiency of up to 98%. CLOU properties were observed at all fuel reactor temperatures, ensuring stable operation even without steam as gasification agent present in the fuel reactor. The results suggest that CaMn_0_._9Mg_0_._1O_3_−_δ is suitable for the use as oxygen carrier in chemical looping combustion of solid biochar and offers higher gas conversion than previously tested materials without CLOU

CaMn0.875Ti0.125O3 as oxygen carrier for chemical-looping combustion with oxygen uncoupling (CLOU)—Experiments in a continuously operating fluidized-bed reactor system

KAUST Repository

Rydén, Magnus

2011-03-01

Particles of the perovskite material CaMn0.875Ti0.125O3 has been examined as oxygen carrier for chemical-looping with oxygen uncoupling, and for chemical-looping combustion of natural gas, by 70h of experiments in a circulating fluidized-bed reactor system. For the oxygen uncoupling experiments, it was found that the particles released O2 in gas phase at temperatures above 720°C when the fuel reactor was fluidized with CO2. The effect increased with increased temperature, and with the O2 partial pressure in the air reactor. At 950°C, the O2 concentration in the outlet from the fuel reactor was in the order of 4.0vol%, if the particles were oxidized in air. For the chemical-looping combustion experiments the combustion efficiency with standard process parameters was in the order of 95% at 950°C, using 1000kg oxygen carrier per MW natural gas, of which about 30% was located in the fuel reactor. Reducing the fuel flow so that 1900kg oxygen carrier per MW natural gas was used improved the combustion efficiency to roughly 99.8%. The particles retained their physical properties, reactivity with CH4 and ability to release gas-phase O2 reasonably well throughout the testing period and there were no problems with the fluidization or formation of solid carbon in the reactor. X-ray diffraction showed that the particles underwent changes in their phase composition though. © 2010 Elsevier Ltd.

Fabrication and processing of next-generation oxygen carrier materials for chemical looping combustion

Energy Technology Data Exchange (ETDEWEB)

Nadarajah, Arunan [Univ. of Toledo, OH (United States)

2017-04-26

Among numerous methods of controlling the global warming effect, Chemical Looping Combustion is known to be the most viable option currently. A key factor to a successful chemical looping process is the presence of highly effective oxygen carriers that enable fuel combustion by going through oxidation and reduction in the presence of air and fuel respectively. In this study, CaMnO_3-δ was used as the base material and doped on the A-site (Sr or La) and B-site (Fe, Ti, Zn and Al) by 10 mol % of dopants. Solid state reaction followed by mechanical extrusion (optimized paste formula) was used as the preparation method A series of novel doped perovskite-type oxygen carrier particles (Ca_xLa (Or Sa)_1-x Mn_1-yByO_3-δ (B-site = Fe, Ti, Al, or Zr)) were synthesized by the proposed extrusion formula. The produced samples were characterized with XRD, SEM, BET and TGA techniques. According to the results obtained from TGA analysis, the oxygen capacity of the samples ranged between 1.2 for CLMZ and 1.75 for CSMF. Reactivity and oxygen uncoupling behaviors of the prepared samples were also evaluated using a fluidized bed chemical looping reactor using methane as the fuel at four different temperatures (800, 850, 900, 950 °C). All of the oxygen carriers showed oxygen uncoupling behavior and they were able to capture and release oxygen. Mass-based conversion of the perovskites was calculated and temperature increase proved to increase the mass-based conversion rate in all of the samples under study. Gas yield was calculated at 950 °C as well, and results showed that CLMZ, CM and CSMF showed 100% gas yields and CLMF and CSMZ showed approximately 85% yield in fluidized bed reactor, which is a high and acceptable quantity. Based on extended reactor tests the modified calcium manganese perovskite structures (CSMF) can be a good candidate for future pilot tests.

Chemical-looping combustion as a new CO{sub 2} management technology

Energy Technology Data Exchange (ETDEWEB)

Mattisson, Tobias; Lyngfelt, Anders [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Energy and Environment; Zafar, Qamar; Johansson, Marcus [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Chemical and Biological Engineering

2006-05-15

Chemical-looping combustion (CLC) is a combustion technology with inherent separation of the greenhouse gas CO{sub 2}. The technique involves the use of a metal oxide as an oxygen carrier which transfers oxygen from combustion air to the fuel, and hence a direct contact between air and fuel is avoided. Two inter-connected fluidized beds, a fuel reactor and an air reactor, are used in the process. In the fuel reactor, the metal oxide is reduced by the reaction with the fuel and in the air reactor; the reduced metal oxide is oxidized with air. The outlet gas from the fuel reactor consists of CO{sub 2} and H{sub 2}O, and almost pure stream of CO{sub 2} is obtained when water is condensed. Considerable research has been conducted on CLC in the last decade with respect to oxygen carrier development, reactor design, system efficiencies and prototype testing. The technique has been demonstrated successfully with both natural gas and syngas as fuel in continuous prototype reactors based on interconnected fluidized beds within the size range 0.3-50 kW, using different types of oxygen carriers based on the metals Ni, Co, Fe, Cu and Mn. From these tests it can be established that almost complete conversion of the fuel can be obtained and 100% CO{sub 2} capture is possible at a low cost. Further, work is going on to adapt the technique for use with solid fuels and for hydrogen production. This paper presents an overview of the research performed on CLC and highlights the current status of the technology.

The energetic performance of a novel hybrid solar thermal and chemical looping combustion plant

International Nuclear Information System (INIS)

Jafarian, Mehdi; Arjomandi, Maziar; Nathan, Graham J.

2014-01-01

Highlights: • A hybrid solar chemical looping combustion power cycle is reported. • The cycle is studied for two configurations, with and without an after-burner. • The oxygen carrier particles are used as storage medium for solar thermal energy. • Total solar shares of 41.4% and 60% are achieved with and without the after-burner. • Efficiencies of 50% and 44.0% are achieved with and without the after-burner. - Abstract: The overall energetic performance of a gas turbine combined cycle powered by a hybrid cycle between a solar thermal and a chemical looping combustion (CLC) system firing methane is reported for two configurations. In one case, the outlet from the air reactor is fed directly to a gas turbine, while in the other an after-burner, also firing methane, is added to increase the gas turbine inlet temperature. The cycle is simulated using Aspen Plus software for the average diurnal profile of normal irradiance for Port Augusta, South Australia. The first law efficiency, total solar absorption efficiency, average and peak fractional power boosts, total solar share, net solar to electrical efficiency, fraction of pressurised CO 2 , incremental CO 2 avoidance and the exergy efficiency for both cycles are reported. The calculations predict a first law efficiency of 50.0% for the cycle employing an after-burner, compared with 44.0% for that without the after-burner. However, this is achieved at the cost of decreasing the solar share from 60.0%, without the after-burner, to 41.4% with it. Also reported is the sensitivity analysis of performance to variations in key operating parameters. The sensitivity analysis shows that further improvements to the performance of the cycle are possible

Feasibility study of sulfates as oxygen carriers for chemical looping processes

Directory of Open Access Journals (Sweden)

Ganesh Kale

2012-12-01

Full Text Available The operational feasibility temperature range of chemical looping combustion (CLC and chemical looping reforming (CLR of the fuels methane, propane, iso-octane and ethanol was explored using the common sulphates

Chemical-looping combustion in a reverse-flow fixed bed reactor

International Nuclear Information System (INIS)

Han, Lu; Bollas, George M.

2016-01-01

A reverse-flow fixed bed reactor concept for CLC (chemical-looping combustion) is explored. The limitations of conventional fixed bed reactors, as applied to CLC, are overcome by reversing the gas flow direction periodically to enhance the mixing characteristics of the bed, thus improving oxygen carrier utilization and energy efficiency with respect to power generation. The reverse-flow reactor is simulated by a dusty-gas model and compared with an equivalent fixed bed reactor without flow reversal. Dynamic optimization is used to calculate conditions at which each reactor operates at maximum energy efficiency. Several cases studies illustrate the benefits of reverse-flow operation for the CLC with CuO and NiO oxygen carriers and methane and syngas fuels. The results show that periodic reversal of the flow during reduction improves the contact between the fuel and unconverted oxygen carrier, enabling the system to suppress unwanted catalytic reactions and axial temperature and conversion gradients. The operational scheme presented reduces the fluctuations of temperature during oxidation and increases the high-temperature heat produced by the process. CLC in a reverse-flow reactor has the potential to achieve higher energy efficiency than conventional fixed bed CLC reactors, when integrated with a downstream gas turbine of a combined cycle power plant. - Highlights: • Reverse-flow fixed bed CLC reactors for combined cycle power systems. • Dynamic optimization tunes operation of batch and transient CLC systems. • The reverse-flow CLC system provides stable turbine-ready gas stream. • Reverse-flow CLC fixed bed reactor has superior CO 2 capture and thermal efficiency.

Simulations of a Circulating Fluidized Bed Chemical Looping Combustion System Utilizing Gaseous Fuel; Simulation de la combustion en boucle chimique d'une charge gazeuse dans un lit fluidise circulant

Energy Technology Data Exchange (ETDEWEB)

Mahalatkar, K.; Kuhlman, J. [West Virginia University, Dept. of Mechanical and Aerospace Engineering, Morgantown, WV, 26506 (United States); Mahalatkar, K. [ANSYS Inc., 3647 Collins Ferry Road Suite A, Morgantown, WV, 26505 (United States); Kuhlman, J.; Huckaby, E.D.; O' Brien, T. [National Energy Technology Laboratory, 3610 Collins Ferry Road, Morgantown, WV, 26507 (United States)

2011-03-15

Numerical studies using Computational Fluid Dynamics (CFD) have been carried out for a complete circulating fluidized bed chemical looping combustor described in the literature (Abad et al., 2006 Fuel 85, 1174-1185). There have been extensive experimental studies in Chemical Looping Combustion (CLC), however CFD simulations of this concept are quite limited. The CLC experiments that were simulated used methane as fuel. A 2-D continuum model was used to describe both the gas and solid phases. Detailed sub-models to account for fluid-particle and particle-particle interaction forces were included. Global models of fuel and carrier chemistry were utilized. The results obtained from CFD were compared with experimental outlet species concentrations, solid circulation rates, solid mass distribution in the reactors, and leakage and dilution rates. The transient CFD simulations provided a reasonable match with the reported experimental data. (authors)

Importance of spinel reaction kinetics in packed-bed chemical looping combustion using a CuO/Al2O3 oxygen carrier

NARCIS (Netherlands)

San Pio, M.A.; Sabatino, F.; Gallucci, F.; van Sint Annaland, M.

2018-01-01

Chemical looping combustion is especially competitive for electrical power generation with integrated CO2 capture when it is operated at high temperatures (1000–1200 °C) and high pressures (15 bar or higher). For these demanding conditions, dynamically operated packed bed reactors have been

A reduced fidelity model for the rotary chemical looping combustion reactor

KAUST Repository

Iloeje, Chukwunwike O.

2017-01-11

The rotary chemical looping combustion reactor has great potential for efficient integration with CO capture-enabled energy conversion systems. In earlier studies, we described a one-dimensional rotary reactor model, and used it to demonstrate the feasibility of continuous reactor operation. Though this detailed model provides a high resolution representation of the rotary reactor performance, it is too computationally expensive for studies that require multiple model evaluations. Specifically, it is not ideal for system-level studies where the reactor is a single component in an energy conversion system. In this study, we present a reduced fidelity model (RFM) of the rotary reactor that reduces computational cost and determines an optimal combination of variables that satisfy reactor design requirements. Simulation results for copper, nickel and iron-based oxygen carriers show a four-order of magnitude reduction in simulation time, and reasonable prediction accuracy. Deviations from the detailed reference model predictions range from 3% to 20%, depending on oxygen carrier type and operating conditions. This study also demonstrates how the reduced model can be modified to deal with both optimization and design oriented problems. A parametric study using the reduced model is then applied to analyze the sensitivity of the optimal reactor design to changes in selected operating and kinetic parameters. These studies show that temperature and activation energy have a greater impact on optimal geometry than parameters like pressure or feed fuel fraction for the selected oxygen carrier materials.

Coal gasification integration with solid oxide fuel cell and chemical looping combustion for high-efficiency power generation with inherent CO2 capture

International Nuclear Information System (INIS)

Chen, Shiyi; Lior, Noam; Xiang, Wenguo

2015-01-01

Highlights: • A novel power system integrating coal gasification with SOFC and chemical looping combustion. • The plant net power efficiency reaches 49.8% with complete CO 2 separation. • Energy and exergy analysis of the entire plant is conducted. • Sensitivity analysis shows a nearly constant power output when SOFC temperature and pressure vary. • NiO oxygen carrier shows higher plant efficiency than using Fe 2 O 3 and CuO. - Abstract: Since solid oxide fuel cells (SOFC) produce electricity with high energy conversion efficiency, and chemical looping combustion (CLC) is a process for fuel conversion with inherent CO 2 separation, a novel combined cycle integrating coal gasification, solid oxide fuel cell, and chemical looping combustion was configured and analyzed. A thermodynamic analysis based on energy and exergy was performed to investigate the performance of the integrated system and its sensitivity to major operating parameters. The major findings include that (1) the plant net power efficiency reaches 49.8% with ∼100% CO 2 capture for SOFC at 900 °C, 15 bar, fuel utilization factor = 0.85, fuel reactor temperature = 900 °C and air reactor temperature = 950 °C, using NiO as the oxygen carrier in the CLC unit. (2) In this parameter neighborhood the fuel utilization factor, the SOFC temperature and SOFC pressure have small effects on the plant net power efficiency because changes in pressure and temperature that increase the power generation by the SOFC tend to decrease the power generation by the gas turbine and steam cycle, and v.v.; an advantage of this system characteristic is that it maintains a nearly constant power output even when the temperature and pressure vary. (3) The largest exergy loss is in the gasification process, followed by those in the CO 2 compression and the SOFC. (4) Compared with the CLC Fe 2 O 3 and CuO oxygen carriers, NiO results in higher plant net power efficiency. To the authors’ knowledge, this is the first

Combustion flame-plasma hybrid reactor systems, and chemical reactant sources

Science.gov (United States)

Kong, Peter C

2013-11-26

Combustion flame-plasma hybrid reactor systems, chemical reactant sources, and related methods are disclosed. In one embodiment, a combustion flame-plasma hybrid reactor system comprising a reaction chamber, a combustion torch positioned to direct a flame into the reaction chamber, and one or more reactant feed assemblies configured to electrically energize at least one electrically conductive solid reactant structure to form a plasma and feed each electrically conductive solid reactant structure into the plasma to form at least one product is disclosed. In an additional embodiment, a chemical reactant source for a combustion flame-plasma hybrid reactor comprising an elongated electrically conductive reactant structure consisting essentially of at least one chemical reactant is disclosed. In further embodiments, methods of forming a chemical reactant source and methods of chemically converting at least one reactant into at least one product are disclosed.

Design and evaluation of an IGCC power plant using iron-based syngas chemical-looping (SCL) combustion

International Nuclear Information System (INIS)

Sorgenfrei, Max; Tsatsaronis, George

2014-01-01

Highlights: • A new concept for power generation including carbon capture was found. • The air reactor temperature significantly influences the net efficiency. • The use of a CO 2 turbine decreases the net efficiency. • Compared to a conventional IGCC with 90% CO 2 capture the net efficiency increases. - Abstract: Chemical-looping combustion (CLC) is a novel and promising combustion technology with inherent separation of the greenhouse gas CO 2 . This paper focuses on the design and thermodynamic evaluation of an integrated gasification combined-cycle (IGCC) process using syngas chemical looping (SCL) combustion for generating electricity. The syngas is provided by coal gasification; the gas from the gasifier is cleaned using high-temperature gas desulfurization (HGD). In this study, the oxygen carrier iron oxide (Fe 2 O 3 ) is selected to oxidize the syngas in a multistage moving-bed reactor. The resulting reduced iron particles then consist of FeO and Fe 3 O 4 . To create a closed-cycle operation, these particles are partially re-oxidized with steam in a fluidized-bed regenerator to pure Fe 3 O 4 and then fully re-oxidized in a fluidized-bed air combustor to Fe 2 O 3 . One advantage of this process is the co-production of hydrogen diluted with water vapor within the steam regenerator. Both the HGD and CLC systems are not under commercial operation so far. This mixture is fed to a gas turbine for the purpose of generating electricity. The gas turbine is expected to exhibit low NO x emissions due to the high ratio of water in the combustion chamber. Cooling the flue gas in the HRSG condenses the water vapor to yield high-purity CO 2 for subsequent compression and disposal. To evaluate the net efficiency, two conventional syngas gasifiers are considered, namely the BGL slagging gasifier and the Shell entrained-flow gasifier. The option of using a CO 2 turbine after the SCL-fuel reactor is also investigated. A sensitivity analysis is performed on the SCL

Recovery Act: Novel Oxygen Carriers for Coal-fueled Chemical Looping

Energy Technology Data Exchange (ETDEWEB)

Pan, Wei-Ping; Cao, Yan

2012-11-30

Chemical Looping Combustion (CLC) could totally negate the necessity of pure oxygen by using oxygen carriers for purification of CO{sub 2} stream during combustion. It splits the single fuel combustion reaction into two linked reactions using oxygen carriers. The two linked reactions are the oxidation of oxygen carriers in the air reactor using air, and the reduction of oxygen carriers in the fuel reactor using fuels (i.e. coal). Generally metal/metal oxides are used as oxygen carriers and operated in a cyclic mode. Chemical looping combustion significantly improves the energy conversion efficiency, in terms of the electricity generation, because it improves the reversibility of the fuel combustion process through two linked parallel processes, compared to the conventional combustion process, which is operated far away from its thermo-equilibrium. Under the current carbon-constraint environment, it has been a promising carbon capture technology in terms of fuel combustion for power generation. Its disadvantage is that it is less mature in terms of technological commercialization. In this DOE-funded project, accomplishment is made by developing a series of advanced copper-based oxygen carriers, with properties of the higher oxygen-transfer capability, a favorable thermodynamics to generate high purity of CO{sub 2}, the higher reactivity, the attrition-resistance, the thermal stability in red-ox cycles and the achievement of the auto-thermal heat balance. This will be achieved into three phases in three consecutive years. The selected oxygen carriers with final-determined formula were tested in a scaled-up 10kW coal-fueled chemical looping combustion facility. This scaled-up evaluation tests (2-day, 8-hour per day) indicated that, there was no tendency of agglomeration of copper-based oxygen carriers. Only trace-amount of coke or carbon deposits on the copper-based oxygen carriers in the fuel reactor. There was also no evidence to show the sulphidization of oxygen

Rational Design of Mixed-Metal Oxides for Chemical Looping Combustion of Coal via Coupled Computational-Experimental Studies

Energy Technology Data Exchange (ETDEWEB)

Mishra, Amit [North Carolina State Univ., Raleigh, NC (United States); Li, Fanxing [North Carolina State Univ., Raleigh, NC (United States); Santiso, Erik [North Carolina State Univ., Raleigh, NC (United States)

2017-09-18

Energy and global climate change are two grand challenges to the modern society. An urgent need exists for development of clean and efficient energy conversion processes. The chemical looping strategy, which utilizes regenerable oxygen carriers (OCs) to indirectly convert carbonaceous fuels via redox reactions, is considered to be one of the more promising approaches for CO2 capture by the U.S. Department of Energy (USDOE). To date, most long-term chemical looping operations were conducted using gaseous fuels, even though direct conversion of coal is more desirable from both economics and CO2 capture viewpoints. The main challenges for direct coal conversion reside in the stringent requirements on oxygen carrier performances. In addition, coal char and volatile compounds are more challenging to convert than gaseous fuels. A promising approach for direct conversion of coal is the so called chemical looping with oxygen uncoupling (CLOU) technique. In the CLOU process, a metal oxide that decomposes at the looping temperature, and releases oxygen to the gas phase is used as the OC. The overarching objective of this project was to discover the fundamental principles for rational design and optimization of oxygen carriers (OC) in coal chemical looping combustion (CLC) processes. It directly addresses Topic Area B of the funding opportunity announcement (FOA) in terms of “predictive description of the phase behavior and mechanical properties” of “mixed metal oxide” based OCs and rational development of new OC materials with superior functionality. This was achieved through studies exploring i) iron-containing mixed-oxide composites as oxygen carriers for CLOU, ii) Ca1-xAxMnO3-δ (A = Sr and Ba) as oxygen carriers for CLOU, iii) CaMn1-xBxO3-δ (B=Al, V, Fe, Co, and Ni) as oxygen carrier for CLOU and iv) vacancy creation energy in Mn-containing perovskites as an indicator chemical looping with oxygen uncoupling.

Calcium and chemical looping technology for power generation and carbon dioxide (CO2) capture solid oxygen- and CO2-carriers

CERN Document Server

Fennell, Paul

2015-01-01

Calcium and Chemical Looping Technology for Power Generation and Carbon Dioxide (CO2) Capture reviews the fundamental principles, systems, oxygen carriers, and carbon dioxide carriers relevant to chemical looping and combustion. Chapters review the market development, economics, and deployment of these systems, also providing detailed information on the variety of materials and processes that will help to shape the future of CO2 capture ready power plants. Reviews the fundamental principles, systems, oxygen carriers, and carbon dioxide carriers relevant to calcium and chemical loopingProvi

Chemical looping combustion. Fuel conversion with inherent CO2 capture

Energy Technology Data Exchange (ETDEWEB)

Brandvoll, Oeyvind

2005-07-01

Chemical looping combustion (CLC) is a new concept for fuel energy conversion with CO2 capture. In CLC, fuel combustion is split into separate reduction and oxidation processes, in which a solid carrier is reduced and oxidized, respectively. The carrier is continuously recirculated between the two vessels, and hence direct contact between air and fuel is avoided. As a result, a stoichiometric amount of oxygen is transferred to the fuel by a regenerable solid intermediate, and CLC is thus a variant of oxy-fuel combustion. In principle, pure CO2 can be obtained from the reduction exhaust by condensation of the produced water vapour. The thermodynamic potential and feasibility of CLC has been studied by means of process simulations and experimental studies of oxygen carriers. Process simulations have focused on parameter sensitivity studies of CLC implemented in 3 power cycles; CLC-Combined Cycle, CLC-Humid Air Turbine and CLC-Integrated Steam Generation. Simulations indicate that overall fuel conversion ratio, oxidation temperature and operating pressure are among the most important process parameters in CLC. A promising thermodynamic potential of CLC has been found, with efficiencies comparable to, - or better than existing technologies for CO2 capture. The proposed oxygen carrier nickel oxide on nickel spinel (NiONiAl) has been studied in reduction with hydrogen, methane and methane/steam as well as oxidation with dry air. It has been found that at atmospheric pressure and temperatures above 600 deg C, solid reduction with dry methane occurs with overall fuel conversion of 92%. Steam methane reforming is observed along with methane cracking as side reactions, yielding an overall selectivity of 90% with regard to solid reduction. If steam is added to the reactant fuel, coking can be avoided. A methodology for long-term investigation of solid chemical activity in a batch reactor is proposed. The method is based on time variables for oxidation. The results for Ni

A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion; Impact du modele de reaction sur les simulations CFD de la combustion en boucle chimique

Energy Technology Data Exchange (ETDEWEB)

Kruggel-Emden, H.; Stepanek, F. [Department of Chemical Engineering, South Kensington Campus, Imperial College London, SW7 2AZ, London (United Kingdom); Kruggel-Emden, H.; Munjiza, A. [Department of Engineering, Queen Mary, University of London, Mile End Road, E1 4NS, London (United Kingdom)

2011-03-15

Chemical Looping Combustion is an energy efficient combustion technology for the inherent separation of carbon dioxide for both gaseous and solid fuels. For scale up and further development of this process multi-phase CFD-based simulations have a strong potential which rely on kinetic models for the solid/gaseous reactions. Reaction models are usually simple in structure in order to keep the computational cost low. They are commonly derived from thermogravimetric experiments. With only few CFD-based simulations performed on chemical looping combustion, there is a lack in understanding of the role and of the sensitivity of the applied chemical reaction model on the outcome of a simulation. The aim of this investigation is therefore the study of three different carrier materials CaSO{sub 4}, Mn{sub 3}O{sub 4} and NiO with the gaseous fuels H{sub 2} and CH{sub 4} in a batch type reaction vessel. Four reaction models namely the linear shrinking core, the spherical shrinking core, the Avrami-Erofeev and a recently proposed multi parameter model are applied and compared on a case by case basis. (authors)

Integration of solid oxide fuel cell (SOFC) and chemical looping combustion (CLC) for ultra-high efficiency power generation and CO2 production

NARCIS (Netherlands)

Spallina, Vincenzo; Nocerino, Pasquale; Romano, Matteo C.; van Sint Annaland, Martin; Campanari, Stefano; Gallucci, Fausto

2018-01-01

This work presents a thermodynamic analysis of the integration of solid oxide fuel cells (SOFCs) with chemical looping combustion (CLC) in natural gas power plants. The fundamental idea of the proposed process integration is to use a dual fluidized-bed CLC process to complete the oxidation of the

Metal ferrite oxygen carriers for chemical looping combustion of solid fuels

Science.gov (United States)

Siriwardane, Ranjani V.; Fan, Yueying

2017-01-31

The disclosure provides a metal ferrite oxygen carrier for the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The metal ferrite oxygen carrier comprises MFe.sub.xO.sub.y on an inert support, where MFe.sub.xO.sub.y is a chemical composition and M is one of Mg, Ca, Sr, Ba, Co, Mn, and combinations thereof. For example, MFe.sub.xO.sub.y may be one of MgFe.sub.2O.sub.4, CaFe.sub.2O.sub.4, SrFe.sub.2O.sub.4, BaFe.sub.2O.sub.4, CoFe.sub.2O.sub.4, MnFeO.sub.3, and combinations thereof. The MFe.sub.xO.sub.y is supported on an inert support. The inert support disperses the MFe.sub.xO.sub.y oxides to avoid agglomeration and improve performance stability. In an embodiment, the inert support comprises from about 5 wt. % to about 60 wt. % of the metal ferrite oxygen carrier and the MFe.sub.xO.sub.y comprises at least 30 wt. % of the metal ferrite oxygen carrier. The metal ferrite oxygen carriers disclosed display improved reduction rates over Fe.sub.2O.sub.3, and improved oxidation rates over CuO.

A reduced fidelity model for the rotary chemical looping combustion reactor

International Nuclear Information System (INIS)

Iloeje, Chukwunwike O.; Zhao, Zhenlong; Ghoniem, Ahmed F.

2017-01-01

Highlights: • Methodology for developing a reduced fidelity rotary CLC reactor model is presented. • The reduced model determines optimal reactor configuration that meets design and operating requirements. • A 4-order of magnitude reduction in computational cost is achieved with good prediction accuracy. • Sensitivity studies demonstrate importance of accurate kinetic parameters for reactor optimization. - Abstract: The rotary chemical looping combustion reactor has great potential for efficient integration with CO_2 capture-enabled energy conversion systems. In earlier studies, we described a one-dimensional rotary reactor model, and used it to demonstrate the feasibility of continuous reactor operation. Though this detailed model provides a high resolution representation of the rotary reactor performance, it is too computationally expensive for studies that require multiple model evaluations. Specifically, it is not ideal for system-level studies where the reactor is a single component in an energy conversion system. In this study, we present a reduced fidelity model (RFM) of the rotary reactor that reduces computational cost and determines an optimal combination of variables that satisfy reactor design requirements. Simulation results for copper, nickel and iron-based oxygen carriers show a four-order of magnitude reduction in simulation time, and reasonable prediction accuracy. Deviations from the detailed reference model predictions range from 3% to 20%, depending on oxygen carrier type and operating conditions. This study also demonstrates how the reduced model can be modified to deal with both optimization and design oriented problems. A parametric study using the reduced model is then applied to analyze the sensitivity of the optimal reactor design to changes in selected operating and kinetic parameters. These studies show that temperature and activation energy have a greater impact on optimal geometry than parameters like pressure or feed fuel

Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

KAUST Repository

Zhao, Zhenlong

2013-01-17

Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two-part series, a new rotary reactor concept for gas-fueled CLC is proposed and analyzed. In part 1, the detailed configuration of the rotary reactor is described. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet and exit. Two purging sectors are used to avoid the mixing between the fuel stream and the air stream. The rotary wheel consists of a large number of channels with copper oxide coated on the inner surface of the channels. The support material is boron nitride, which has high specific heat and thermal conductivity. Gas flows through the reactor at elevated pressure, and it is heated to a high temperature by fuel combustion. Typical design parameters for a thermal capacity of 1 MW have been proposed, and a simplified model is developed to predict the performances of the reactor. The potential drawbacks of the rotary reactor are also discussed. © 2012 American Chemical Society.

Simulations of a Circulating Fluidized Bed Chemical Looping Combustion System Utilizing Gaseous Fuel Simulation de la combustion en boucle chimique d’une charge gazeuse dans un lit fluidisé circulant

Directory of Open Access Journals (Sweden)

Mahalatkar K.

2011-05-01

Full Text Available Numerical studies using Computational Fluid Dynamics (CFD have been carried out for a complete circulating fluidized bed chemical looping combustor described in the literature (Abad et al., 2006 Fuel 85, 1174-1185. There have been extensive experimental studies in Chemical Looping Combustion (CLC, however CFD simulations of this concept are quite limited. The CLC experiments that were simulated used methane as fuel. A 2-D continuum model was used to describe both the gas and solid phases. Detailed sub-models to account for fluid-particle and particleparticle interaction forces were included. Global models of fuel and carrier chemistry were utilized. The results obtained from CFD were compared with experimental outlet species concentrations, solid circulation rates, solid mass distribution in the reactors, and leakage and dilution rates. The transient CFD simulations provided a reasonable match with the reported experimental data. Des études numériques de simulation des écoulements (CFD ont été réalisées sur un lit fluidisé circulant opérant en combustion par boucle chimique (CLC décrit dans la littérature (Abad et al., 2006 Fuel 85, 1174-1185. Si de nombreuses études expérimentales ont été conduites pour étudier le procédé CLC, les études concernant la simulation des écoulements par CFD de ce concept sont très limitées. Le système de combustion en boucle chimique simulé dans cette étude concerne la combustion d’une charge gazeuse (méthane. Un modèle 2-D à deux phases continues a été utilisé pour décrire les phases gaz et solide avec des sous-modèles détaillés pour décrire les forces d’interactions entre fluideparticule et particule-particule. Des modèles cinétiques globaux ont été intégrés pour décrire les réactions de combustion et de transformation du matériau transporteur d’oxygène. Les résultats obtenus par CFD ont été comparés aux concentrations expérimentales mesurées des diff

Chemical Looping Combustion of Hematite Ore with Methane and Steam in a Fluidized Bed Reactor

Directory of Open Access Journals (Sweden)

Samuel Bayham

2017-08-01

Full Text Available Chemical looping combustion is considered an indirect method of oxidizing a carbonaceous fuel, utilizing a metal oxide oxygen carrier to provide oxygen to the fuel. The advantage is the significantly reduced energy penalty for separating out the CO2 for reuse or sequestration in a carbon-constrained world. One of the major issues with chemical looping combustion is the cost of the oxygen carrier. Hematite ore is a proposed oxygen carrier due to its high strength and resistance to mechanical attrition, but its reactivity is rather poor compared to tailored oxygen carriers. This problem is further exacerbated by methane cracking, the subsequent deposition of carbon and the inability to transfer oxygen at a sufficient rate from the core of the particle to the surface for fuel conversion to CO2. Oxygen needs to be readily available at the surface to prevent methane cracking. The purpose of this work was to demonstrate the use of steam to overcome this issue and improve the conversion of the natural gas to CO2, as well as to provide data for computational fluid dynamics (CFD validation. The steam will gasify the deposited carbon to promote the methane conversion. This work studies the performance of hematite ore with methane and steam mixtures in a 5 cm fluidized bed up to approximately 140 kPa. Results show an increased conversion of methane in the presence of steam (from 20–45% without steam to 60–95% up to a certain point, where performance decreases. Adding steam allows the methane conversion to carbon dioxide to be similar to the overall methane conversion; it also helped to prevent carbon accumulation from occurring on the particle. In general, the addition of steam to the feed gas increased the methane conversion. Furthermore, the addition of steam caused the steam methane reforming reaction to form more hydrogen and carbon monoxide at higher steam and methane concentrations, which was not completely converted at higher concentrations and

Thermal and mechanical behaviour of oxygen carrier materials for chemical looping combustion in a packed bed reactor

International Nuclear Information System (INIS)

Jacobs, M.; Van Noyen, J.; Larring, Y.; Mccann, M.; Pishahang, M.; Amini, S.; Ortiz, M.; Galluci, F.; Sint-Annaland, M.V.; Tournigant, D.; Louradour, E.; Snijkers, F.

2015-01-01

Highlights: • Ilmenite-based oxygen carriers were developed for packed-bed chemical looping. • Addition of Mn_2O_3 increased mechanical strength and microstructure of the carriers. • Oxygen carriers were able to withstand creep and thermal cycling up to 1200 °C. • Ilmenite-based granules are a promising shape for packed-bed reactor conditions. - Abstract: Chemical looping combustion (CLC) is a promising carbon capture technology where cyclic reduction and oxidation of a metallic oxide, which acts as a solid oxygen carrier, takes place. With this system, direct contact between air and fuel can be avoided, and so, a concentrated CO_2 stream is generated after condensation of the water in the exit gas stream. An interesting reactor system for CLC is a packed bed reactor as it can have a higher efficiency compared to a fluidized bed concept, but it requires other types of oxygen carrier particles. The particles must be larger to avoid a large pressure drop in the reactor and they must be mechanically strong to withstand the severe reactor conditions. Therefore, oxygen carriers in the shape of granules and based on the mineral ilmenite were subjected to thermal cycling and creep tests. The mechanical strength of the granules before and after testing was investigated by crush tests. In addition, the microstructure of these oxygen particles was studied to understand the relationship between the physical properties and the mechanical performance. It was found that the granules are a promising shape for a packed bed reactor as no severe degradation in strength was noticed upon thermal cycling and creep testing. Especially, the addition of Mn_2O_3 to the ilmenite, which leads to the formation of an iron–manganese oxide, seems to results in stronger granules than the other ilmenite-based granules.

Analysis of thermally coupled chemical looping combustion-based power plants with carbon capture

KAUST Repository

Iloeje, Chukwunwike

2015-04-01

© 2015 Elsevier Ltd. A number of CO2 capture-enabled power generation technologies have been proposed to address the negative environmental impact of CO2 emission. One important barrier to adopting these technologies is the associated energy penalty. Chemical-looping Combustion (CLC) is an oxy-combustion technology that can significantly lower this penalty. It utilizes an oxygen carrier to transfer oxygen from air/oxidizing stream in an oxidation reactor to the fuel in a reduction reactor. Conventional CLC reactor designs employ two separate reactors, with metal/metal oxide particles circulating pneumatically in-between. One of the key limitations of these designs is the entropy generation due to reactor temperature difference, which lowers the cycle efficiency. Zhao et al. (Zhao et al., 2014; Zhao and Ghoniem, 2014) proposed a new CLC rotary reactor design, which overcomes this limitation. This reactor consists of a single rotating wheel with micro-channels designed to maintain thermal equilibrium between the fuel and air sides. This study uses three thermodynamic models of increasing fidelity to demonstrate that the internal thermal coupling in the rotary CLC reactor creates the potential for improved cycle efficiency. A theoretical availability model and an ideal thermodynamic cycle model are used to define the efficiency limits of CLC systems, illustrate the impact of reactor thermal coupling and discuss relevant criteria. An Aspen Plus® model of a regenerative CLC cycle is then used to show that this thermal coupling raises the cycle efficiency by up to 2% points. A parametric study shows that efficiency varies inversely with pressure, with a maximum of 51% at 3bar, 1000C and 60% at 4bar, 1400C. The efficiency increases with CO2 fraction at high pressure ratios but exhibits a slight inverse dependence at low pressure ratios. The parametric study shows that for low purge steam demand, steam generation improves exhaust heat recovery and increases efficiency

Use of Hopcalite derived Cu-Mn mixed oxide as Oxygen Carrier for Chemical Looping with Oxygen Uncoupling Process

OpenAIRE

Adánez-Rubio, Iñaki; Abad Secades, Alberto; Gayán Sanz, Pilar; Adánez-Rubio, Imanol; Diego Poza, Luis F. de; Garcia-Labiano, Francisco; Adánez Elorza, Juan

2016-01-01

Chemical-Looping with Oxygen Uncoupling (CLOU) is an alternative Chemical Looping process for the combustion of solid fuels with inherent CO2 capture. The CLOU process needs a material as oxygen carrier with the ability to give gaseous O2 at suitable temperatures for solid fuel combustion, e.g. copper oxide and manganese oxide. In this work, treated commercial Carulite 300® was evaluated as oxygen carrier for CLOU. Carulite 300® is a hopcalite material composed of 29.2 wt.% CuO and 67.4 wt.% ...

Chemical Kinetics of Hydrocarbon Ignition in Practical Combustion Systems

International Nuclear Information System (INIS)

Westbrook, C.K.

2000-01-01

Chemical kinetic factors of hydrocarbon oxidation are examined in a variety of ignition problems. Ignition is related to the presence of a dominant chain branching reaction mechanism that can drive a chemical system to completion in a very short period of time. Ignition in laboratory environments is studied for problems including shock tubes and rapid compression machines. Modeling of the laboratory systems are used to develop kinetic models that can be used to analyze ignition in practical systems. Two major chain branching regimes are identified, one consisting of high temperature ignition with a chain branching reaction mechanism based on the reaction between atomic hydrogen with molecular oxygen, and the second based on an intermediate temperature thermal decomposition of hydrogen peroxide. Kinetic models are then used to describe ignition in practical combustion environments, including detonations and pulse combustors for high temperature ignition, and engine knock and diesel ignition for intermediate temperature ignition. The final example of ignition in a practical environment is homogeneous charge, compression ignition (HCCI) which is shown to be a problem dominated by the kinetics intermediate temperature hydrocarbon ignition. Model results show why high hydrocarbon and CO emissions are inevitable in HCCI combustion. The conclusion of this study is that the kinetics of hydrocarbon ignition are actually quite simple, since only one or two elementary reactions are dominant. However, there are many combustion factors that can influence these two major reactions, and these are the features that vary from one practical system to another

Viability of fuel switching of a gas-fired power plant operating in chemical looping combustion mode

International Nuclear Information System (INIS)

Basavaraja, R.J.; Jayanti, S.

2015-01-01

CLC (chemical looping combustion) promises to be a more efficient way of CO 2 capture than conventional oxy-fuel combustion or post-combustion absorption. While much work has been done on CLC in the past two decades, the issue of multi-fuel compatibility has not been addressed sufficiently, especially with regard to plant layout and reactor design. In the present work, it is shown that this is non-trivial in the case of a CLC-based power plant. The underlying factors have been examined in depth and design criteria for fuel compatibility have been formulated. Based on these, a layout has been developed for a power plant which can run with either natural gas or syngas without requiring equipment changes either on the steam side or on the furnace side. The layout accounts for the higher CO 2 compression costs associated with the use of syngas in place of natural gas. The ideal thermodynamic cycle efficiency, after accounting for the energy penalty of CO 2 compression, is 43.11% and 41.08%, when a supercritical steam cycle is used with natural gas and syngas, respectively. It is shown that fuel switching can be enabled by incorporating the compatibility conditions at the design stage itself. - Highlights: • Concept of fuel sensitivity of plant layout with carbon capture and sequestration. • Power plant layout for natural gas and syngas as fuels. • Criteria for compatibility of air and fuel reactors for dual fuel mode operation. • Layout of a plant for carbon-neutral or carbon negative power generation

Development of Computational Approaches for Simulation and Advanced Controls for Hybrid Combustion-Gasification Chemical Looping

Energy Technology Data Exchange (ETDEWEB)

Joshi, Abhinaya; Lou, Xinsheng; Neuschaefer, Carl; Chaudry, Majid; Quinn, Joseph

2012-07-31

This document provides the results of the project through September 2009. The Phase I project has recently been extended from September 2009 to March 2011. The project extension will begin work on Chemical Looping (CL) Prototype modeling and advanced control design exploration in preparation for a scale-up phase. The results to date include: successful development of dual loop chemical looping process models and dynamic simulation software tools, development and test of several advanced control concepts and applications for Chemical Looping transport control and investigation of several sensor concepts and establishment of two feasible sensor candidates recommended for further prototype development and controls integration. There are three sections in this summary and conclusions. Section 1 presents the project scope and objectives. Section 2 highlights the detailed accomplishments by project task area. Section 3 provides conclusions to date and recommendations for future work.

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.

Hot spot detection system for vanes or blades of a combustion turbine

Science.gov (United States)

Twerdochlib, M.

1999-02-02

This invention includes a detection system that can determine if a turbine component, such as a turbine vane or blade, has exceeded a critical temperature, such as a melting point, along any point along the entire surface of the vane or blade. This system can be employed in a conventional combustion turbine having a compressor, a combustor and a turbine section. Included within this system is a chemical coating disposed along the entire interior surface of a vane or blade and a closed loop cooling system that circulates a coolant through the interior of the vane or blade. If the temperature of the vane or blade exceeds a critical temperature, the chemical coating will be expelled from the vane or blade into the coolant. Since while traversing the closed loop cooling system the coolant passes through a detector, the presence of the chemical coating in the coolant will be sensed by the system. If the chemical coating is detected, this indicates that the vane or blade has exceeded a critical temperature. 5 figs.

Process/Equipment Co-Simulation on Syngas Chemical Looping Process

Energy Technology Data Exchange (ETDEWEB)

Zeng, Liang; Zhou, Qiang; Fan, Liang-Shih

2012-09-30

The chemical looping strategy for fossil energy applications promises to achieve an efficient energy conversion system for electricity, liquid fuels, hydrogen and/or chemicals generation, while economically separate CO{sub 2} by looping reaction design in the process. Chemical looping particle performance, looping reactor engineering, and process design and applications are the key drivers to the success of chemical looping process development. In order to better understand and further scale up the chemical looping process, issues such as cost, time, measurement, safety, and other uncertainties need to be examined. To address these uncertainties, advanced reaction/reactor modeling and process simulation are highly desired and the modeling efforts can accelerate the chemical looping technology development, reduce the pilot-scale facility design time and operating campaigns, as well as reduce the cost and technical risks. The purpose of this work is thus to conduct multiscale modeling and simulations on the key aspects of chemical looping technology, including particle reaction kinetics, reactor design and operation, and process synthesis and optimization.

Advanced closed loop combustion control of a LTC diesel engine based on in-cylinder pressure signals

International Nuclear Information System (INIS)

Carlucci, A.P.; Laforgia, D.; Motz, S.; Saracino, R.; Wenzel, S.P.

2014-01-01

Highlights: • We have proposed an in-cylinder pressure-based closed loop combustion control. • We have tested the control on an engine at the test bench. • We have tested the control on the engine equipping a Euro 6-compliant vehicle. • The control is effective in increasing torque stability and reduce engine noise. - Abstract: The adoption of diesel LTC combustion concepts is widely recognised as a practical way to reduce simultaneously nitric oxides and particulate emission levels from diesel internal combustion engines. However, several challenges have to be faced up when implementing diesel LTC concepts in real application vehicles. In particular, achieving acceptable performance concerning the drivability comfort, in terms of output torque stability and combustion noise during engine dynamic transients, is generally a critical point. One of the most promising solutions to improve the LTC combustion operation lays in the exploitation of closed loop combustion control, based on in-cylinder pressure signals. In this work, the application of an in-cylinder pressure-based closed loop combustion control to a Euro 6-compliant demonstrator vehicle has been developed. The main challenges deriving from the control of the LTC combustion, directly affecting the engine/vehicle performance, have been analysed in detail. In order to overcome these drawbacks, a new control function, integrated into the base closed loop system, has been designed. The performance of the new function have been experimentally tested at the engine test bench. Results showed a significant enhancement of the LTC operation, in terms of both combustion stability and noise reduction during engine transients. The new function was also implemented on a real vehicle, thus proving the potential of the new control concept in realistic operating conditions

Chemical kinetics and combustion modeling

Energy Technology Data Exchange (ETDEWEB)

Miller, J.A. [Sandia National Laboratories, Livermore, CA (United States)

1993-12-01

The goal of this program is to gain qualitative insight into how pollutants are formed in combustion systems and to develop quantitative mathematical models to predict their formation rates. The approach is an integrated one, combining low-pressure flame experiments, chemical kinetics modeling, theory, and kinetics experiments to gain as clear a picture as possible of the process in question. These efforts are focused on problems involved with the nitrogen chemistry of combustion systems and on the formation of soot and PAH in flames.

Kinetics of the reduction of hematite (Fe{sub 2}O{sub 3}) by methane (CH{sub 4}) during chemical looping combustion: A global mechanism

Energy Technology Data Exchange (ETDEWEB)

Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Richards, George; Carpenter, Stephen

2013-10-01

Chemical-looping combustion (CLC) has emerged as a promising technology for fossil fuel combustion which produces a sequestration ready concentrated CO{sub 2} stream in power production. A CLC system is composed with two reactors, an air and a fuel reactor. An oxygen carrier such as hematite (94%Fe{sub 2}O{sub 3}) circulates between the reactors, which transfers the oxygen necessary for the fuel combustion from the air to the fuel. An important issue for the CLC process is the selection of metal oxide as oxygen carrier, since it must retain its reactivity through many cycles. The primary objective of this work is to develop a global mechanism with respective kinetics rate parameters such that CFD simulations can be performed for large systems. In this study, thermogravimetric analysis (TGA) of the reduction of hematite (Fe{sub 2}O{sub 3}) in a continuous stream of CH{sub 4} (15, 20, and 35%) was conducted at temperatures ranging from 700 to 825{degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2} and H{sub 2}O at the early stage of reaction and H{sub 2} and CO at the final stage of reactions. A kinetic model based on two parallel reactions, 1) first-order irreversible rate kinetics and 2) Avrami equation describing nucleation and growth processes, was applied to the reduction data. It was found, that the reaction rates for both reactions increase with, both, temperature and the methane concentration in inlet gas.

Comparative study in LTC Combustion between a short HP EGR loop without cooler and a variable lift and duration system

Energy Technology Data Exchange (ETDEWEB)

Bression, Guillaume; Pacaud, Pierre; Soleri, Dominique; Cessou, Jerome [IFP (France); Azoulay, David [Renault Powertrain Div. (France); Lawrence, David [Mechadyne (United Kingdom); Doradoux, Laurent; Guerrassi, Noureddine [Delphi Diesel Systems (France)

2008-07-01

In order to reach future Diesel emission standards such as Euro 6 or Tier 2 Bin 5, NO{sub x} emissions need to be dramatically reduced. Advanced technologies and engine settings such as higher EGR rates, reduced compression ratio, EGR cooler and low-pressure EGR loop - depending on vehicle application - may help to reach this target whilst maintaining low CO{sub 2} emissions and fuel consumption. However, the resulting low combustion temperatures and the low air-fuel ratios lead to a significant increase in HC and CO emissions, especially during the start-up phase prior to catalyst light-off. Moreover, high levels of EGR make transient operation even more difficult. So HC-CO emissions and EGR transient operation represent two key issues that could limit the extension of this alternative combustion mode. Consequently, an in-depth investigation of a variable lift and duration (VLD) system was performed to overcome these problems on a 4-cylinder engine, which was also equipped with a dual HP-LP EGR loop. The VLD system tested in this paper produces a variable camshaft-operated exhaust valve re-opening, which is controlled by a hydraulic rotary actuator, ensuring quick and accurate regulation of the internal gas recirculation (IGR). By increasing gas temperature in the combustion chamber, this advanced technology allows us to reduce HC-CO emissions by 50% under 3 bar BMEP. Although efficient, this technology has to be compared with other solutions from a cost-to-value point of view. The aim of this paper is firstly to compare the double lift exhaust system with a short route high-performance EGR loop without cooler by quantifying their respective gains on steady state points of the NEDC cycle, then by evaluating their potential performances during transient conditions. With the short-route EGR, the potential in HC-CO emission reduction remains significant on a large scale of engine temperatures representative of engine warm up. However, the VLD system allows us to

Heat Integration of the Water-Gas Shift Reaction System for Carbon Sequestration Ready IGCC Process with Chemical Looping

Energy Technology Data Exchange (ETDEWEB)

Juan M. Salazara; Stephen E. Zitney; Urmila M. Diwekara

2010-01-01

Integrated gasification combined cycle (IGCC) technology has been considered as an important alternative for efficient power systems that can reduce fuel consumption and CO2 emissions. One of the technological schemes combines water-gas shift reaction and chemical-looping combustion as post gasification techniques in order to produce sequestration-ready CO2 and potentially reduce the size of the gas turbine. However, these schemes have not been energetically integrated and process synthesis techniques can be applied to obtain an optimal flowsheet. This work studies the heat exchange network synthesis (HENS) for the water-gas shift reaction train employing a set of alternative designs provided by Aspen energy analyzer (AEA) and combined in a process superstructure that was simulated in Aspen Plus (AP). This approach allows a rigorous evaluation of the alternative designs and their combinations avoiding all the AEA simplifications (linearized models of heat exchangers). A CAPE-OPEN compliant capability which makes use of a MINLP algorithm for sequential modular simulators was employed to obtain a heat exchange network that provided a cost of energy that was 27% lower than the base case. Highly influential parameters for the pos gasification technologies (i.e. CO/steam ratio, gasifier temperature and pressure) were calculated to obtain the minimum cost of energy while chemical looping parameters (oxidation and reduction temperature) were ensured to be satisfied.

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.

Analysis of exergy loss of gasoline surrogate combustion process based on detailed chemical kinetics

International Nuclear Information System (INIS)

Sun, Hongjie; Yan, Feng; Yu, Hao; Su, W.H.

2015-01-01

Highlights: • We explored the exergy loss sources of gasoline engine like combustion process. • The model combined non-equilibrium thermodynamics with detailed chemical kinetics. • We explored effects of initial conditions on exergy loss of combustion process. • Exergy loss decreases 15% of fuel chemical exergy by design of initial conditions. • Correspondingly, the second law efficiency increases from 38.9% to 68.9%. - Abstract: Chemical reaction is the most important source of combustion irreversibility in premixed conditions, but details of the exergy loss mechanisms have not been explored yet. In this study numerical analysis based on non-equilibrium thermodynamics combined with detailed chemical kinetics is conducted to explore the exergy loss mechanism of gasoline engine like combustion process which is simplified as constant volume combustion. The fuel is represented by the common accepted gasoline surrogates which consist of four components: iso-octane (57%), n-heptane (16%), toluene (23%), and 2-pentene (4%). We find that overall exergy loss is mainly composed of three peaks along combustion generated from chemical reactions in three stages, the conversion from large fuel molecules into small molecules (as Stage 1), the H 2 O 2 loop-related reactions (as Stage 2), and the violent oxidation reactions of CO, H, and O (as Stage 3). The effects of individual combustion boundaries, including temperature, pressure, equivalence ratio, oxygen concentration, on combustion exergy loss have been widely investigated. The combined effects of combustion boundaries on the total loss of gasoline surrogates are also investigated. We find that in a gasoline engine with a compression ratio of 10, the total loss can be reduced from 31.3% to 24.3% using lean combustion. The total loss can be further reduced to 22.4% by introducing exhaust gas recirculation and boosting the inlet charge. If the compression ratio is increased to 17, the total loss can be decreased to

Combustion chemical vapor desposited coatings for thermal barrier coating systems

Energy Technology Data Exchange (ETDEWEB)

Hampikian, J.M.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States)

1995-10-01

The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings.

Removal of CO2 in closed loop off-gas treatment systems

International Nuclear Information System (INIS)

Clemens, M.K.; Nelson, P.A.; Swift, W.M.

1994-01-01

A closed loop test system has been installed at Argonne National Laboratory (ANL) to demonstrate off-gas treatment, absorption, and purification systems to be used for incineration and vitrification of hazardous and mixed waste. Closed loop systems can virtually eliminate the potential for release of hazardous or toxic materials to the atmosphere during both normal and upset conditions. In initial tests, a 250,000 Btu/h (75 kW thermal) combustor was operated in an open loop to produce a combustion product gas. The CO 2 in these tests was removed by reaction with a fluidized bed of time to produce CaCO 3 . Subsequently, recirculation system was installed to allow closed loop operation with the addition of oxygen to the recycle stream to support combustion. Commercially marketed technologies for removal of CO 2 can be adapted for use on closed loop incineration systems. The paper also describes the Absorbent Solution Treatment (AST) process, based on modifications to commercially demonstrated gas purification technologies. In this process, a side loop system is added to the main loop for removing CO 2 in scrubbing towers using aqueous-based CO 2 absorbents. The remaining gas is returned to the incinerator with oxygen addition. The absorbent is regenerated by driving off the CO 2 and water vapor, which are released to the atmosphere. Contaminants are either recycled for further treatment or form precipitates which are removed during the purification and regeneration process. There are no direct releases of gases or particulates to the environment. The CO 2 and water vapor go through two changes of state before release, effectively separating these combustion products from contaminants released during incineration. The AST process can accept a wide range of waste streams. The system may be retrofitted to existing Facilities or included in the designs for new installations

The fate of sulphur in the Cu-based Chemical Looping with Oxygen Uncoupling (CLOU) Process

International Nuclear Information System (INIS)

Adánez-Rubio, Iñaki; Abad, Alberto; Gayán, Pilar; García-Labiano, Francisco; Diego, Luis F. de; Adánez, Juan

2014-01-01

Highlights: • 15 h of CLOU experiments using lignite were carried out in a continuously unit. • The sulphur split between fuel- and air-reactor streams in the process was analysed. • Most of the sulphur introduced with the fuel exits as SO 2 at the fuel-reactor. • The use of a carbon separation system to reduce the S emission was evaluated. • Coals with high S content can be burnt in a CLOU process with a Cu-based material. - Abstract: The Chemical Looping with Oxygen Uncoupling (CLOU) process is a type of Chemical Looping Combustion (CLC) technology that allows the combustion of solid fuels with air, as with conventional combustion, through the use of oxygen carriers that release gaseous oxygen inside the fuel reactor. The aim of this work was to study the behaviour of the sulphur present in fuel during CLOU combustion. Experiments using lignite as fuel were carried out in a continuously operated 1.5 kW th CLOU unit during more than 15 h. Particles containing 60 wt.% CuO on MgAl 2 O 4 , prepared by spray drying, were used as the oxygen carrier in the CLOU process. The temperature in the fuel reactor varied between 900 and 935 °C. CO 2 capture, combustion efficiency and the sulphur split between fuel and air reactor streams in the process were analysed. Complete combustion of the fuel to CO 2 and H 2 O was found in all experiments. Most of the sulphur introduced with the fuel exited as SO 2 at the fuel reactor outlet, although a small amount of SO 2 was measured at the air reactor outlet. The SO 2 concentration in the air reactor exit flow decreased as the temperature in the fuel reactor increased. A carbon capture efficiency of 97.6% was achieved at 935 °C, with 87.9 wt.% of the total sulphur exiting as SO 2 in the fuel reactor. Both the reactivity and oxygen transport capacity of the oxygen carrier were unaffected during operation with a high sulphur content fuel, and agglomeration problems did not occur. Predictions were calculated regarding the use

Closed loop solar chemical heat pipe

International Nuclear Information System (INIS)

Levy, M.; Levitan, R.; Rosin, H.; Rubin, R.

1991-01-01

The system used for the closed loop operation of the solar chemical heat pipe comprises a reformer, heated by the solar furnace, a methanator and a storage assembly containing a compressor and storage cylinders. (authors). 7 figs

Operation of the NETL Chemical Looping Reactor with Natural Gas and a Novel Copper-Iron Material

Energy Technology Data Exchange (ETDEWEB)

Bayham, Sanuel [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Straub, Doug [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Weber, Justin [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

2017-02-01

As part of the U.S. Department of Energy’s Advanced Combustion Program, the National Energy Technology Laboratory’s Research and Innovation Center (NETL R&IC) is investigating the feasibility of a novel combustion concept in which the GHG emissions can be significantly reduced. This concept involves burning fuel and air without mixing these two reactants. If this concept is technically feasible, then CO₂ emissions can be significantly reduced at a much lower cost than more conventional approaches. This indirect combustion concept has been called Chemical Looping Combustion (CLC) because an intermediate material (i.e., a metaloxide) is continuously cycled to oxidize the fuel. This CLC concept is the focus of this research and will be described in more detail in the following sections.

Hydrogen production from natural gas using an iron-based chemical looping technology: Thermodynamic simulations and process system analysis

International Nuclear Information System (INIS)

Kathe, Mandar V.; Empfield, Abbey; Na, Jing; Blair, Elena; Fan, Liang-Shih

2016-01-01

Highlights: • Design of iron-based chemical looping process using moving bed for H_2 from CH_4. • Auto-thermal operation design using thermodynamic rationale for 90% carbon capture. • Cold gas efficiency: 5% points higher than Steam Methane Reforming baseline case. • Net thermal efficiency: 6% points higher than Steam Methane Reforming baseline case. • Sensitivity analysis: Energy recovery scheme, operating pressure, no carbon capture. - Abstract: Hydrogen (H_2) is a secondary fuel derived from natural gas. Currently, H_2 serves as an important component in refining operations, fertilizer production, and is experiencing increased utilization in the transportation industry as a clean combustion fuel. In recent years, industry and academia have focused on developing technology that reduces carbon emissions. As a result, there has been an increase in the technological developments for producing H_2 from natural gas. These technologies aim to minimize the cost increment associated with clean energy production. The natural gas processing chemical looping technology, developed at The Ohio State University (OSU), employs an iron-based oxygen carrier and a novel gas–solid counter-current moving bed reactor for H_2 production. Specifically, this study examines the theoretical thermodynamic limits for full conversion of natural gas through iron-based oxygen carrier reactions with methane (CH_4), by utilizing simulations generated with ASPEN modeling software. This study initially investigates the reducer and the oxidizer thermodynamic phase diagrams then derives an optimal auto-thermal operating condition for the complete loop simulation. This complete loop simulation is initially normalized for analysis on the basis of one mole of carbon input from natural gas. The H_2 production rate is then scaled to match that of the baseline study, using a full-scale ASPEN simulation for computing cooling loads, water requirements and net parasitic energy consumption. The

Design of a rotary reactor for chemical-looping combustion. Part 1: Fundamentals and design methodology

KAUST Repository

Zhao, Zhenlong

2014-04-01

Chemical-looping combustion (CLC) is a novel and promising option for several applications including carbon capture (CC), fuel reforming, H 2 generation, etc. Previous studies demonstrated the feasibility of performing CLC in a novel rotary design with micro-channel structures. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet, and depleted air and product streams at exit. The rotary wheel consists of a large number of micro-channels with oxygen carriers (OC) coated on the inner surface of the channel walls. In the CC application, the OC oxidizes the fuel while the channel is in the fuel zone to generate undiluted CO2, and is regenerated while the channel is in the air zone. In this two-part series, the effect of the reactor design parameters is evaluated and its performance with different OCs is compared. In Part 1, the design objectives and criteria are specified and the key parameters controlling the reactor performance are identified. The fundamental effects of the OC characteristics, the design parameters, and the operating conditions are studied. The design procedures are presented on the basis of the relative importance of each parameter, enabling a systematic methodology of selecting the design parameters and the operating conditions with different OCs. Part 2 presents the application of the methodology to the designs with the three commonly used OCs, i.e., nickel, copper, and iron, and compares the simulated performances of the designs. © 2013 Elsevier Ltd. All rights reserved.

Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 2: Base Case and Sensitivity Analysis

KAUST Repository

Zhao, Zhenlong

2013-01-17

Part 1 (10.1021/ef3014103) of this series describes a new rotary reactor for gas-fueled chemical-looping combustion (CLC), in which, a solid wheel with microchannels rotates between the reducing and oxidizing streams. The oxygen carrier (OC) coated on the surfaces of the channels periodically adsorbs oxygen from air and releases it to oxidize the fuel. A one-dimensional model is also developed in part 1 (10.1021/ef3014103). This paper presents the simulation results based on the base-case design parameters. The results indicate that both the fuel conversion efficiency and the carbon separation efficiency are close to unity. Because of the relatively low reduction rate of copper oxide, fuel conversion occurs gradually from the inlet to the exit. A total of 99.9% of the fuel is converted within 75% of the channel, leading to 25% redundant length near the exit, to ensure robustness. In the air sector, the OC is rapidly regenerated while consuming a large amount of oxygen from air. Velocity fluctuations are observed during the transition between sectors because of the complete reactions of OCs. The gas temperature increases monotonically from 823 to 1315 K, which is mainly determined by the solid temperature, whose variations with time are limited within 20 K. The overall energy in the solid phase is balanced between the reaction heat release, conduction, and convective cooling. In the sensitivity analysis, important input parameters are identified and varied around their base-case values. The resulting changes in the model-predicted performance revealed that the most important parameters are the reduction kinetics, the operating pressure, and the feed stream temperatures. © 2012 American Chemical Society.

Experimental investigation of the chemical looping method on a 1 MW pilot plant; Experimentelle Untersuchung des Chemical Looping Verfahrens an einer 1 MW Versuchsanlage

Energy Technology Data Exchange (ETDEWEB)

Orth, Matthias

2014-08-27

Attempting to counteract the consequences of climate change, leading industrial nations have agreed on reducing their CO{sub 2} emissions significantly. To reach these reduction goals, it is essential to reduce the CO{sub 2} emissions in the field of energy conversion. This PHD thesis covers the field of chemical looping combustion, a technology that uses fossil fuels for energy conversion with inherent capture of CO{sub 2}. Since the research regarding chemical looping had so far focused mainly on lab scale or small scale experiments, a 1 MW pilot plant has been erected at Technische Universitaet Darmstadt in order to investigate the process in a semi-industrial scale and to check the process efficiency with commercially usable equipment. This pilot consists of two interconnected fluidized bed reactors and has an overall height of more than 11 m. In this thesis, some experiments with ilmenite - used as the oxygen carrier - are explained. Furthermore, the design, erection and commissioning of the pilot plant are presented as well as the results of the first test campaigns. The evaluation of the latter proves that the process can be handled in the design configuration and that CO{sub 2} can be safely captured in a pilot plant of this scale.

Combustion behaviour of ultra clean coal obtained by chemical demineralisation

Energy Technology Data Exchange (ETDEWEB)

F. Rubiera; A. Arenillas; B. Arias; J.J. Pis; I. Suarez-Ruiz; K.M. Steel; J.W. Patrick [Instituto Nacional del Carbon, CSIC, Oviedo (Spain)

2003-10-01

The increasing environmental concern caused by the use of fossil fuels and the concomitant need for improved combustion efficiency is leading to the development of new coal cleaning and utilisation processes. However, the benefits achieved by the removal of most mineral matter from coal either by physical or chemical methods can be annulled if poor coal combustibility characteristics are attained. In this work a high volatile bituminous coal with 6% ash content was subjected to chemical demineralisation via hydrofluoric and nitric acid leaching, the ash content of the clean coal was reduced to 0.3%. The original and treated coals were devolatilised in a drop tube furnace and the structure and morphology of the resultant chars was analysed by optical and scanning electron microscopies. The reactivity characteristics of the chars were studied by isothermal combustion tests in air at different temperatures in a thermogravimetric system. Comparison of the combustion behaviour and pollutant emissions of both coals was conducted in a drop tube furnace operating at 1000{sup o}C. The results of this work indicate that the char obtained from the chemically treated coal presents very different structure, morphology and reactivity behaviour than the char from the original coal. The changes induced by the chemical treatment increased the combustion efficiency determined in the drop tube furnace, in fact higher burnout levels were obtained for the demineralised coal.

A review of active control approaches in stabilizing combustion systems in aerospace industry

Science.gov (United States)

Zhao, Dan; Lu, Zhengli; Zhao, He; Li, X. Y.; Wang, Bing; Liu, Peijin

2018-02-01

Self-sustained combustion instabilities are one of the most plaguing challenges and problems in lean-conditioned propulsion and land-based engine systems, such as rocket motors, gas turbines, industrial furnace and boilers, and turbo-jet thrust augmenters. Either passive or active control in open- or closed-loop configurations can be implemented to mitigate such instabilities. One of the classical disadvantages of passive control is that it is only implementable to a designed combustor over a limited frequency range and can not respond to the changes in operating conditions. Compared with passive control approaches, active control, especially in closed-loop configuration is more adaptive and has inherent capacity to be implemented in practice. The key components in closed-loop active control are 1) sensor, 2) controller (optimization algorithm) and 3) dynamic actuator. The present work is to outline the current status, technical challenges and development progress of the active control approaches (in open- or closed-loop configurations). A brief description of feedback control, adaptive control, model-based control and sliding mode control are provided first by introducing a simplified Rijke-type combustion system. The modelled combustion system provides an invaluable platform to evaluate the performance of these feedback controllers and a transient growth controller. The performance of these controllers are compared and discussed. An outline of theoretical, numerical and experimental investigations are then provided to overview the research and development progress made during the last 4 decades. Finally, potential, challenges and issues involved with the design, application and implementation of active combustion control strategies on a practical engine system are highlighted.

Nonlinear model predictive control for chemical looping process

Science.gov (United States)

Joshi, Abhinaya; Lei, Hao; Lou, Xinsheng

2017-08-22

A control system for optimizing a chemical looping ("CL") plant includes a reduced order mathematical model ("ROM") that is designed by eliminating mathematical terms that have minimal effect on the outcome. A non-linear optimizer provides various inputs to the ROM and monitors the outputs to determine the optimum inputs that are then provided to the CL plant. An estimator estimates the values of various internal state variables of the CL plant. The system has one structure adapted to control a CL plant that only provides pressure measurements in the CL loops A and B, a second structure adapted to a CL plant that provides pressure measurements and solid levels in both loops A, and B, and a third structure adapted to control a CL plant that provides full information on internal state variables. A final structure provides a neural network NMPC controller to control operation of loops A and B.

Thermogravimetric Analysis of Modified Hematite by Methane (CH{sub 4}) for Chemical-Looping Combustion: A Global Kinetics Mechanism

Energy Technology Data Exchange (ETDEWEB)

Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Miller, Duane D

2013-10-01

Iron oxide (Fe{sub 2}O{sub 3}) or in its natural form (hematite) is a potential material to capture CO{sub 2} through the chemical-looping combustion (CLC) process. It is known that magnesium (Mg) is an effective methyl cleaving catalyst and as such it has been combined with hematite to assess any possible enhancement to the kinetic rate for the reduction of Fe{sub 2}O{sub 3} with methane. Therefore, in order to evaluate its effectiveness as a hematite additive, the behaviors of Mg-modified hematite samples (hematite –5% Mg(OH){sub 2}) have been analyzed with regard to assessing any enhancement to the kinetic rate process. The Mg-modified hematite was prepared by hydrothermal synthesis. The reactivity experiments were conducted in a thermogravimetric analyzer (TGA) using continuous stream of CH{sub 4} (5, 10, and 20%) at temperatures ranging from 700 to 825 {degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2}, H{sub 2}O, H{sub 2} and CO in the gaseous product. The kinetic data at reduction step obtained by isothermal experiments could be well fitted by two parallel rate equations. The modified hematite samples showed higher reactivity as compared to unmodified hematite samples during reduction at all investigated temperatures.

Three loop HTL perturbation theory at finite temperature and chemical potential

Energy Technology Data Exchange (ETDEWEB)

Strickland, Michael [Department of Physics, Kent State University, Kent, OH 44242 (United States); Andersen, Jens O. [Department of Physics, Norwegian University of Science and Technology, N-7491 Trondheim (Norway); Bandyopadhyay, Aritra; Haque, Najmul; Mustafa, Munshi G. [Theory Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Su, Nan [Faculty of Physics, University of Bielefeld, D-33615 Bielefeld (Germany)

2014-11-15

In this proceedings contribution we present a recent three-loop hard-thermal-loop perturbation theory (HTLpt) calculation of the thermodynamic potential for a finite temperature and chemical potential system of quarks and gluons. We compare the resulting pressure, trace anomaly, and diagonal/off-diagonal quark susceptibilities with lattice data. We show that there is good agreement between the three-loop HTLpt analytic result and available lattice data.

Gas-solids kinetics of CuO/Al2O3 as an oxygen carrier for high-pressure chemical looping processes : the influence of the total pressure

NARCIS (Netherlands)

San Pio Bordeje, M.A.; Gallucci, F.; Roghair, I.; van Sint Annaland, M.

2017-01-01

Copper oxide on alumina is often used as oxygen carrier for chemical looping combustion owing to its very high reduction rates at lower temperatures and its very good mechanical and chemical stability at not too high temperatures. In this work, the redox kinetics of CuO/Al2O3 have been studied at

Chemical Pollution from Combustion of Modern Spacecraft Materials

Science.gov (United States)

Mudgett, Paul D.

2013-01-01

Fire is one of the most critical contingencies in spacecraft and any closed environment including submarines. Currently, NASA uses particle based technology to detect fires and hand-held combustion product monitors to track the clean-up and restoration of habitable cabin environment after the fire is extinguished. In the future, chemical detection could augment particle detection to eliminate frequent nuisance false alarms triggered by dust. In the interest of understanding combustion from both particulate and chemical generation, NASA Centers have been collaborating on combustion studies at White Sands Test Facility using modern spacecraft materials as fuels, and both old and new technology to measure the chemical and particulate products of combustion. The tests attempted to study smoldering pyrolysis at relatively low temperatures without ignition to flaming conditions. This paper will summarize the results of two 1-week long tests undertaken in 2012, focusing on the chemical products of combustion. The results confirm the key chemical products are carbon monoxide (CO), hydrogen cyanide (HCN), hydrogen fluoride (HF) and hydrogen chloride (HCl), whose concentrations depend on the particular material and test conditions. For example, modern aerospace wire insulation produces significant concentration of HF, which persists in the test chamber longer than anticipated. These compounds are the analytical targets identified for the development of new tunable diode laser based hand-held monitors, to replace the aging electrochemical sensor based devices currently in use on the International Space Station.

Mechanism of Methane Chemical Looping Combustion with Hematite Promoted with CeO ₂

Energy Technology Data Exchange (ETDEWEB)

Miller, Duane D.; Siriwardane, Ranjani

2013-08-15

Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion that produces sequestration-ready CO{sub 2} stream, reducing the energy penalty of CO{sub 2} separation from flue gases. An effective oxygen carrier for CLC will readily react with the fuel gas and will be reoxidized upon contact with oxygen. This study investigated the development of a CeO{sub 2}-promoted Fe{sub 2}O{sub 3}-hematite oxygen carrier suitable for the methane CLC process. Composition of CeO{sub 2} is between 5 and 25 wt % and is lower than what is generally used for supports in Fe{sub 2}O{sub 3} carrier preparations. The incorporation of CeO{sub 2} to the natural ore hematite strongly modifies the reduction behavior in comparison to that of CeO{sub 2} and hematite alone. Temperature-programmed reaction studies revealed that the addition of even 5 wt % CeO{sub 2} enhances the reaction capacity of the Fe{sub 2}O{sub 3} oxygen carrier by promoting the decomposition and partial oxidation of methane. Fixed-bed reactor data showed that the 5 wt % cerium oxides with 95 wt % iron oxide produce 2 times as much carbon dioxide in comparison to the sum of carbon dioxide produced when the oxides were tested separately. This effect is likely due to the reaction of CeO{sub 2} with methane forming intermediates, which are reactive for extracting oxygen from Fe{sub 2}O{sub 3} at a considerably faster rate than the rate of the direct reaction of Fe{sub 2}O{sub 3} with methane. These studies reveal that 5 wt % CeO{sub 2}/Fe{sub 2}O{sub 3} gives stable conversions over 15 reduction/oxidation cycles. Lab-scale reactor studies (pulsed mode) suggest the methane reacts initially with CeO{sub 2} lattice oxygen to form partial oxidation products (CO + H{sub 2}), which continue to react with oxygen from neighboring Fe{sub 2}O{sub 3}, leading to its complete oxidation to form CO{sub 2}. The reduced cerium oxide promotes the methane decomposition reaction to form C + H{sub 2}, which continue to

Simulation of the Fuel Reactor of a Coal-Fired Chemical Looping Combustor

Science.gov (United States)

Mahalatkar, Kartikeya; O'Brien, Thomas; Huckaby, E. David; Kuhlman, John

2009-06-01

Responsible carbon management (CM) will be required for the future utilization of coal for power generation. CO2 separation is the more costly component of CM, not sequestration. Most methods of capture require a costly process of gas separation to obtain a CO2-rich gas stream. However, recently a process termed Chemical Looping Combustion (CLC) has been proposed, in which an oxygen-carrier is used to provide the oxygen for combustion. This process quite naturally generates a separate exhaust gas stream containing mainly H2O and CO2 but requires two reaction vessels, an Air Reactor (AR) and a Fuel Reactor (FR). The carrier (M for metal, the usual carrier) is oxidized in the AR. This highly exothermic process provides heat for power generation. The oxidized carrier (MO) is separated from this hot, vitiated air stream and transported to the FR where it oxidizes the hydrocarbon fuel, yielding an exhaust gas stream of mainly H2O and CO2. This process is usually slightly endothermic so that the carrier must also transport the necessary heat of reaction. The reduced carrier (M) is then returned to the air reactor for regeneration, hence the term "looping." The net chemical reaction and energy release is identical to that of conventional combustion of the fuel. However, CO2 separation is easily achieved, the only operational penalty being the slight pressure losses required to circulate the carrier. CLC requires many unit operations involving gas-solid or granular flow. To utilize coal in the fuel reactor, in either a moving bed or bubbling fluidized bed, the granular flow is especially critical. The solid coal fuel must be heated by the recycled metal oxide, driving off moisture and volatile material. The remaining char must be gasified by H2O (or CO2), which is recycled from the product stream. The gaseous product of these reactions must then contact the MO before leaving the bed to obtain complete conversion to H2O and CO2. Further, the reduced M particles must be

Hadron–Quark Combustion as a Nonlinear, Dynamical System

Science.gov (United States)

Ouyed, Amir; Ouyed, Rachid; Jaikumar, Prashanth

2018-03-01

The hadron-quark combustion front is a system that couples various processes, such as chemical reactions, hydrodynamics, diffusion, and neutrino transport. Previous numerical work has shown that this system is very nonlinear, and can be very sensitive to some of these processes. In these proceedings, we contextualize the hadron-quark combustion as a nonlinear system, subject to dramatic feedback triggered by leptonic weak decays and neutrino transport.

The redox reaction kinetics of Sinai ore for chemical looping combustion applications

International Nuclear Information System (INIS)

Ksepko, Ewelina; Babiński, Piotr; Nalbandian, Lori

2017-01-01

Highlights: • Redox reaction kinetics of Fe-Mn-rich Sinai ore was determined by TGA. • The most suitable model for reduction was D3, while R3 for oxidation. • Activation energies 35.3 and 16.70 kJ/mole were determined for reduction and oxidation. • Repetitive redox reactions favor the formation of spinel phases in Sinai ore. • Multiple redox cycles induce formation of extensive porosity of the particles. - Abstract: The objective of this work was to study the use of Sinai ore, a Fe–Mn-based ore from Egypt, as a low-cost oxygen carrier (OC) in Chemical Looping Combustion (CLC). The Sinai ore was selected because it possesses relatively high amounts of iron and manganese oxides. Furthermore, those oxides have low cost, very favorable environmental and thermodynamic properties for the CLC process. The performance of the Sinai ore as an OC in CLC was compared to that of ilmenite (Norway Tellnes mine), the most extensively studied naturally occurring Fe-based mineral. The kinetics of the reduction and oxidation reactions with the two minerals were studied using a thermogravimetric analyzer (TGA). Experiments were conducted under isothermal conditions, with multiple redox cycles, at temperatures between 750 and 950 °C. For the reduction and oxidation reactions, different concentrations of CH_4 (10–25 vol.%) and O_2 (5–20 vol.%) were applied, respectively. The kinetic parameters, such as the activation energy (E_a), pre-exponential factor (A_0), and reaction order (n), were determined for the redox reactions. Furthermore, models of the redox reactions were selected by means of a model-fitting method. For the Sinai ore, the D3 model (3-dimensional diffusion) was suitable for modeling reduction reaction kinetics. The calculated E_a was 35.3 kJ/mole, and the reaction order was determined to be approximately 0.76. The best fit for the oxidation reaction was obtained for the R3 model (shrinking core). The oxidation (regeneration) reaction E_a was equal to 16

Process integration of chemical looping combustion with oxygen uncoupling in a coal-fired power plant

International Nuclear Information System (INIS)

Spinelli, Maurizio; Peltola, Petteri; Bischi, Aldo; Ritvanen, Jouni; Hyppänen, Timo; Romano, Matteo C.

2016-01-01

High-temperature solid looping processes for CCS (carbon capture and storage) represent a class of promising technologies that enables CO2 capture with relatively low net efficiency penalties. The novel concept of the CLOU (Chemical Looping with Oxygen Uncoupling) process is based on a system of two interconnected fluidized bed reactors that operate at atmospheric pressure. In the fuel reactor, the capability of certain metal oxides to spontaneously release molecular oxygen at high temperatures is exploited to promote the direct conversion of coal in an oxygen-rich atmosphere. As a novel CO_2 capture concept, the CLOU process requires the optimization of design and operation parameters, which may substantially influence the total power plant performance. This study approaches this issue by performing joint simulations of CLOU reactors using a 1.5D model and a steam cycle power plant. A sensitivity analysis has been performed to investigate the performance and main technical issues that are related to the integration of a CLOU island in a state-of-the-art USC (ultra-supercritical) power plant. In particular, the effect of the key process parameters has been evaluated. Superior performance has been estimated for the power plant, with electrical efficiencies of approximately 42% and more than 95% CO2 avoided. - Highlights: • Process modeling and simulation of CLOU integrated in USC coal power plant carried out. • Comprehensive sensitivity analysis on Cu-based CLOU process performed. • Electrical efficiencies of 42% and more than 95% CO_2 avoided obtained. • Reactor size and operating conditions suitable for industrial applications.

Operation of the NETL Chemical Looping Reactor with Natural Gas and a Novel Copper-Iron Material

Energy Technology Data Exchange (ETDEWEB)

Straub, Douglas [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Bayham, Samuel [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Weber, Justin [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

2017-02-21

The proposed Clean Power Plan requires CO₂ emission reductions of 30% by 2030 and further reductions are targeted by 2050. The current strategies to achieve the 30% reduction targets do not include options for coal. However, the 2016 Annual Energy Outlook suggests that coal will continue to provide more electricity than renewable sources for many regions of the country in 2035. Therefore, cost effective options to reduce greenhouse gas emissions from fossil fuel power plants are vital in order to achieve greenhouse gas reduction targets beyond 2030. As part of the U.S. Department of Energy’s Advanced Combustion Program, the National Energy Technology Laboratory’s Research and Innovation Center (NETL R&IC) is investigating the feasibility of a novel combustion concept in which the GHG emissions can be significantly reduced. This concept involves burning fuel and air without mixing these two reactants. If this concept is technically feasible, then CO₂ emissions can be significantly reduced at a much lower cost than more conventional approaches. This indirect combustion concept has been called Chemical Looping Combustion (CLC) because an intermediate material (i.e., a metal-oxide) is continuously cycled to oxidize the fuel. This CLC concept is the focus of this research and will be described in more detail in the following sections. The solid material that is used to transport oxygen is called an oxygen carrier material. The cost, durability, and performance of this material is a key issue for the CLC technology. Researchers at the NETL R&IC have developed an oxygen carrier material that consists of copper, iron, and alumina. This material has been tested extensively using lab scale instruments such as thermogravimetric analysis (TGA), scanning electron microscopy (SEM), mechanical attrition (ASTM D5757), and small fluidized bed reactor tests. This report will describe the results from a realistic, circulating, proof-of-concept test that was

Hadron–Quark Combustion as a Nonlinear, Dynamical System

Directory of Open Access Journals (Sweden)

Amir Ouyed

2018-03-01

Full Text Available The hadron–quark combustion front is a system that couples various processes, such as chemical reactions, hydrodynamics, diffusion, and neutrino transport. Previous numerical work has shown that this system is very nonlinear, and can be very sensitive to some of these processes. In these proceedings, we contextualize the hadron–quark combustion as a nonlinear system, subject to dramatic feedback triggered by leptonic weak decays and neutrino transport.

Theoretical Adiabatic Temperature and Chemical Composition of Sodium Combustion Flame

International Nuclear Information System (INIS)

Okano, Yasushi; Yamaguchi, Akira

2003-01-01

Sodium fire safety analysis requires fundamental combustion properties, e.g., heat of combustion, flame temperature, and composition. We developed the GENESYS code for a theoretical investigation of sodium combustion flame.Our principle conclusions on sodium combustion under atmospheric air conditions are (a) the maximum theoretical flame temperature is 1950 K, and it is not affected by the presence of moisture; the uppermost limiting factor is the chemical instability of the condensed sodium-oxide products under high temperature; (b) the main combustion product is liquid Na 2 O in dry air condition and liquid Na 2 O with gaseous NaOH in moist air; and (c) the chemical equilibrium prediction of the residual gaseous reactants in the flame is indispensable for sodium combustion modeling

Challenges in simulation of chemical processes in combustion furnaces

Energy Technology Data Exchange (ETDEWEB)

Hupa, M.; Kilpinen, P. [Aabo Akademi, Turku (Finland)

1996-12-31

The presentation gives an introduction to some of the present issues and problems in treating the complex chemical processes in combustion. The focus is in the coupling of the hydrocarbon combustion process with nitrogen oxide formation and destruction chemistry in practical furnaces or flames. Detailed kinetic modelling based on schemes of elementary reactions are shown to be a useful novel tool for identifying and studying the key reaction paths for nitrogen oxide formation and destruction in various systems. The great importance of the interaction between turbulent mixing and combustion chemistry is demonstrated by the sensitivity of both methane oxidation chemistry and fuel nitrogen conversion chemistry to the reactor and mixing pattern chosen for the kinetic calculations. The fluidized bed combustion (FBC) nitrogen chemistry involves several important heterogeneous reactions. Particularly the char in the bed plays an essential role. Recent research has advanced rapidly and the presentation proposes an overall picture of the fuel nitrogen reaction routes in circulating FBC conditions. (author)

Challenges in simulation of chemical processes in combustion furnaces

Energy Technology Data Exchange (ETDEWEB)

Hupa, M; Kilpinen, P [Aabo Akademi, Turku (Finland)

1997-12-31

The presentation gives an introduction to some of the present issues and problems in treating the complex chemical processes in combustion. The focus is in the coupling of the hydrocarbon combustion process with nitrogen oxide formation and destruction chemistry in practical furnaces or flames. Detailed kinetic modelling based on schemes of elementary reactions are shown to be a useful novel tool for identifying and studying the key reaction paths for nitrogen oxide formation and destruction in various systems. The great importance of the interaction between turbulent mixing and combustion chemistry is demonstrated by the sensitivity of both methane oxidation chemistry and fuel nitrogen conversion chemistry to the reactor and mixing pattern chosen for the kinetic calculations. The fluidized bed combustion (FBC) nitrogen chemistry involves several important heterogeneous reactions. Particularly the char in the bed plays an essential role. Recent research has advanced rapidly and the presentation proposes an overall picture of the fuel nitrogen reaction routes in circulating FBC conditions. (author)

Thermodynamic analysis of a dual loop heat recovery system with trilateral cycle applied to exhaust gases of internal combustion engine for propulsion of the 6800 TEU container ship

International Nuclear Information System (INIS)

Choi, Byung Chul; Kim, Young Min

2013-01-01

A dual loop waste heat recovery power generation system that comprises an upper trilateral cycle and a lower organic Rankine cycle, in which discharged exhaust gas heat is recovered and re-used for propulsion power, was theoretically applied to an internal combustion engine for propulsion in a 6800 TEU container ship. The thermodynamic properties of this exhaust gas heat recovery system, which vary depending on the boundary temperature between the upper and lower cycles, were also investigated. The results confirmed that this dual loop exhaust gas heat recovery power generation system exhibited a maximum net output of 2069.8 kW, and a maximum system efficiency of 10.93% according to the first law of thermodynamics and a maximum system exergy efficiency of 58.77% according to the second law of thermodynamics. In this case, the energy and exergy efficiencies of the dual loop system were larger than those of the single loop trilateral cycle. Further, in the upper trilateral cycle, the volumetric expansion ratio of the turbine could be considerably reduced to an adequate level to be employed in the practical system. When this dual loop exhaust gas heat recovery power generation system was applied to the main engine of the container ship, which was actually in operation, a 2.824% improvement in propulsion efficiency was confirmed in comparison to the case of a base engine. This improvement in propulsion efficiency resulted in about 6.06% reduction in the specific fuel oil consumption and specific CO 2 emissions of the main engine during actual operation. - Highlights: • WHRS was theoretically applied to exhaust gas of a main engine for ship propulsion. • A dual loop EG-WHRS using water and R1234yf as working fluids has been suggested. • Limitation of single loop trilateral cycle was improved by the dual loop system. • The propulsion efficiency of 2.824% was improved by the dual loop EG-WHRS. • This resulted in about 6.06% reduction in the SFOC and specific CO

Experimental investigation of the chemical looping method on a 1 MW pilot plant

International Nuclear Information System (INIS)

Orth, Matthias

2014-01-01

Attempting to counteract the consequences of climate change, leading industrial nations have agreed on reducing their CO 2 emissions significantly. To reach these reduction goals, it is essential to reduce the CO 2 emissions in the field of energy conversion. This PHD thesis covers the field of chemical looping combustion, a technology that uses fossil fuels for energy conversion with inherent capture of CO 2 . Since the research regarding chemical looping had so far focused mainly on lab scale or small scale experiments, a 1 MW pilot plant has been erected at Technische Universitaet Darmstadt in order to investigate the process in a semi-industrial scale and to check the process efficiency with commercially usable equipment. This pilot consists of two interconnected fluidized bed reactors and has an overall height of more than 11 m. In this thesis, some experiments with ilmenite - used as the oxygen carrier - are explained. Furthermore, the design, erection and commissioning of the pilot plant are presented as well as the results of the first test campaigns. The evaluation of the latter proves that the process can be handled in the design configuration and that CO 2 can be safely captured in a pilot plant of this scale.

Rapid computation of chemical equilibrium composition - An application to hydrocarbon combustion

Science.gov (United States)

Erickson, W. D.; Prabhu, R. K.

1986-01-01

A scheme for rapidly computing the chemical equilibrium composition of hydrocarbon combustion products is derived. A set of ten governing equations is reduced to a single equation that is solved by the Newton iteration method. Computation speeds are approximately 80 times faster than the often used free-energy minimization method. The general approach also has application to many other chemical systems.

Supersonic Combustion of Hydrogen Jets System in Hypersonic Stream

International Nuclear Information System (INIS)

Zhapbasbaev, U.K.; Makashev, E.P.

2003-01-01

The data of calculated theoretical investigations of diffusive combustion of plane supersonic hydrogen jets in hypersonic stream received with Navier-Stokes parabola equations closed by one-para metrical (k-l) model of turbulence and multiply staged mechanism of hydrogen oxidation are given. Combustion mechanisms depending on the operating parameters are discussing. The influences of air stream composition and ways off fuel feed to the length of ignition delay and level quantity of hydrogen bum-out have been defined. The calculated theoretical results of investigations permit to make the next conclusions: 1. The diffusive combustion of the system of plane supersonic hydrogen jets in hypersonic flow happens in the cellular structures with alternation zones of intensive running of chemical reactions with their inhibition zones. 2. Gas dynamic and heat Mach waves cause a large - scale viscous formation intensifying mixing of fuel with oxidizer. 3. The system ignition of plane supersonic hydrogen jets in hypersonic airy co-flow happens with the formation of normal flame front of hydrogen airy mixture with transition to the diffusive combustion. 4. The presence of active particles in the flow composition initiates the ignition of hydrogen - airy mixture, provides the intensive running of chemical reactions and shortens the length of ignition delay. 5. The supersonic combustion of hydrogel-airy mixture is characterized by two zones: the intensive chemical reactions with an active energy heat release is occurring in the first zone and in the second - a slow hydrogen combustion limited by the mixing of fuel with oxidizer. (author)

Comparison of different chemical kinetic mechanisms of methane combustion in an internal combustion engine configuration

OpenAIRE

Ennetta Ridha; Hamdi Mohamed; Said Rachid

2008-01-01

Three chemical kinetic mechanisms of methane combustion were tested and compared using the internal combustion engine model of Chemkin 4.02 [1]: one-step global reaction mechanism, four-step mechanism, and the standard detailed scheme GRIMECH 3.0. This study shows good concordances, especially between the four-step and the detailed mechanisms in the prediction of temperature and main species profiles. But reduced schemes were incapables to predict pollutant emissions in an internal combustion...

Effect of surface Fe-S hybrid structure on the activity of the perfect and reduced α-Fe2O3(001) for chemical looping combustion

Science.gov (United States)

Xiao, Xianbin; Qin, Wu; Wang, Jianye; Li, Junhao; Dong, Changqing

2018-05-01

Sulfurization of the gradually reduced Fe2O3 surfaces is inevitable while Fe2O3 is used as an oxygen carrier (OC) for coal chemical looping combustion (CLC), which will result in formation of Fe-S hybrid structure on the surfaces. The Fe-S hybrid structure will directly alter the reactivity of the surfaces. Therefore, detailed properties of Fe-S hybrid structure over the perfect and reduced Fe2O3(001) surfaces, and its effect on the interfacial interactions, including CO oxidization and decomposition on the surfaces, were investigated by using density functional theory (DFT) calculations. The S atom prefers to chemically bind to Fe site with electron transfer from the surfaces to the S atom, and a deeper reduction of Fe2O3(001) leads to an increasing interaction between S and Fe. The formation of Fe-S hybrid structure alters the electronic properties of the gradually reduced Fe2O3(001) surfaces, promoting CO oxidation on the surfaces ranging from Fe2O3 to FeO, but depressing carbon deposition on the surfaces ranging from FeO to Fe. The sulfurized FeO acts as a watershed to realize relatively high CO oxidation rate and low carbon deposition. Results provided a fundamental understanding for controlling and optimizing the CLC processes.

Exergy analysis of a coal/biomass co-hydrogasification based chemical looping power generation system

International Nuclear Information System (INIS)

Yan, Linbo; Yue, Guangxi; He, Boshu

2015-01-01

Power generation from co-utilization of coal and biomass is very attractive since this technology can not only save the coal resource but make sufficient utilization of biomass. In addition, with this concept, net carbon discharge per unit electric power generation can also be sharply reduced. In this work, a coal/biomass co-hydrogasification based chemical looping power generation system is presented and analyzed with the assistance of Aspen Plus. The effects of different operating conditions including the biomass mass fraction, R_b, the hydrogen recycle ratio, R_h_r, the hydrogasification pressure, P_h_g, the iron to fuel mole ratio, R_i_f, the reducer temperature, T_r_e, the oxidizer temperature, T_o_x, and the fuel utilization factor, U_f of the SOFC (solid oxide fuel cell) on the system operation results including the energy efficiency, η_e, the total energy efficiency, η_t_e, the exergy efficiency, η_e_x, the total exergy efficiency, η_t_e_x and the carbon capture rate, η_c_c, are analyzed. The energy and exergy balances of the whole system are also calculated and the corresponding Sankey diagram and Grassmann diagram are drawn. Under the benchmark condition, exergy efficiencies of different units in the system are calculated. η_t_e, η_t_e_x and η_c_c of the system are also found to be 43.6%, 41.2% and 99.1%, respectively. - Highlights: • A coal/biomass co-hydrogasification based chemical looping power generation system is setup. • Sankey and Grassmann diagrams are presented based on the energy and exergy balance calculations. • Sensitivity analysis is done to understand the system operation characteristics. • Total energy and exergy efficiencies of this system can be 43.6% and 41.2%, respectively. • About 99.1% of the carbon contained in coal and biomass can be captured in this system.

Combustion driven NF3 chemical laser

International Nuclear Information System (INIS)

1975-01-01

Stable, inert, non-corrosive nitrogen trifluoride gas and an inorganic source of hydrogen or deuterium gas are used as reactants in a compact combustion driven chemical laser. Nitrogen trifluoride is introduced into the combustion chamber of a chemical laser together with a hydrogen source selected from hydrogen, hydrazine, ammonia, acetylene, or benzene and the deuterated isotopes thereof and an optional inert diluent gas wherein the nitrogen trifluoride and the hydrogen- or deuterium-source gas hypergolically reacted upon heating to initiation temperature. Dissociated products from the reaction pass into a laser cavity at supersonic velocities where they are reacted with a source gas which is the isotopic opposite of the gas introduced into the combustor and which has been heated by regenerative cooling. Excited molecules of hydrogen fluoride or deuterium fluoride produce laser radiation which leaves the optical resonator cavity transversely to the flow of gases

Apparatus and method for solid fuel chemical looping combustion

Science.gov (United States)

Siriwardane, Ranjani V; Weber, Justin M

2015-04-14

The disclosure provides an apparatus and method utilizing fuel reactor comprised of a fuel section, an oxygen carrier section, and a porous divider separating the fuel section and the oxygen carrier section. The porous divider allows fluid communication between the fuel section and the oxygen carrier section while preventing the migration of solids of a particular size. Maintaining particle segregation between the oxygen carrier section and the fuel section during solid fuel gasification and combustion processes allows gases generated in either section to participate in necessary reactions while greatly mitigating issues associated with mixture of the oxygen carrier with char or ash products. The apparatus and method may be utilized with an oxygen uncoupling oxygen carrier such as CuO, Mn.sub.3O.sub.4, or Co.sub.3O.sub.4, or utilized with a CO/H.sub.2 reducing oxygen carrier such as Fe.sub.2O.sub.3.

Reduced Chemical Kinetic Mechanisms for JP-8 Combustion

National Research Council Canada - National Science Library

Montgomery, Christopher J; Cannon, S. M; Mawid, M. A; Sekar, B

2002-01-01

Using CARM (Computer Aided Reduction Method), a computer program that automates the mechanism reduction process, six different reduced chemical kinetic mechanisms for JP-8 combustion have been generated...

Chemical decontamination method in nuclear facility system

International Nuclear Information System (INIS)

Takahashi, Ryota; Sakai, Hitoshi; Oka, Shigehiro.

1996-01-01

Pumps and valves in a closed recycling loop system incorporating materials to be chemically decontaminated are decomposed, a guide plate having the decomposed parts as an exit/inlet of a decontaminating liquid is formed, and a decontaminating liquid recycling loop comprising a recycling pump and a heater is connected to the guide plate. Decontaminating liquid from a decontaminating liquid storage tank is supplied to the decontaminating liquid recycling loop. With such constitutions, the decontaminating liquid is filled in the recycling closed loop system incorporating materials to be decontaminated, and the materials to be decontaminated are chemically decontaminated. The decontaminating liquid after the decontamination is discharged and flows, if necessary, in a recycling system channel for repeating supply and discharge. After the decontamination, the guide plate is removed and returned to the original recycling loop. When pipelines of a reactor recycling system are decontaminated, the amount of decontaminations can be decreased, and reforming construction for assembling the recycling loop again, which requires cutting for pipelines in the system is no more necessary. Accordingly, the amount of wastes can be decreased, and therefore, the decontamination operation is facilitated and radiation dose can be reduced. (T.M.)

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor.

Science.gov (United States)

Lapa, N; Barbosa, R; Lopes, M H; Mendes, B; Abelha, P; Boavida, D; Gulyurtlu, I; Oliveira, J Santos

2007-08-17

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub-products of such type

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

Energy Technology Data Exchange (ETDEWEB)

Lapa, N. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)]. E-mail: ncsn@fct.unl.pt; Barbosa, R. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Lopes, M.H. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Mendes, B. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Abelha, P. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Gulyurtlu, I. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Santos Oliveira, J. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)

2007-08-17

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

International Nuclear Information System (INIS)

Lapa, N.; Barbosa, R.; Lopes, M.H.; Mendes, B.; Abelha, P.; Gulyurtlu, I.; Santos Oliveira, J.

2007-01-01

In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

Chemical Kinetic Modeling of 2-Methylhexane Combustion

KAUST Repository

Mohamed, Samah Y.

2015-03-30

Accurate chemical kinetic combustion models of lightly branched alkanes (e.g., 2-methylalkanes) are important for investigating the combustion behavior of diesel, gasoline, and aviation fuels. Improving the fidelity of existing kinetic models is a necessity, as new experiments and advanced theories show inaccuracy in certain portions of the models. This study focuses on updating thermodynamic data and kinetic model for a gasoline surrogate fuel, 2-methylhexane, with recently published group values and rate rules. These update provides a better agreement with rapid compression machine measurements of ignition delay time, while also strengthening the fundamental basis of the model.

Analysis of the chemical equilibrium of combustion at constant volume

Directory of Open Access Journals (Sweden)

Marius BREBENEL

2014-04-01

Full Text Available Determining the composition of a mixture of combustion gases at a given temperature is based on chemical equilibrium, when the equilibrium constants are calculated on the assumption of constant pressure and temperature. In this paper, an analysis of changes occurring when combustion takes place at constant volume is presented, deriving a specific formula of the equilibrium constant. The simple reaction of carbon combustion in pure oxygen in both cases (constant pressure and constant volume is next considered as example of application, observing the changes occurring in the composition of the combustion gases depending on temperature.

Process design of a hydrogen production plant from natural gas with CO2 capture based on a novel Ca/Cu chemical loop

International Nuclear Information System (INIS)

Martínez, I.; Romano, M.C.; Fernández, J.R.; Chiesa, P.; Murillo, R.; Abanades, J.C.

2014-01-01

Highlights: • Process design of a H 2 production plant based on a novel Ca/Cu looping process is presented. • CuO reduction with syngas provides energy for CaCO 3 calcination. • The effect of operating conditions on plant performance indexes is analysed. • Carbon capture efficiencies of around 94% are obtained. • Around 6% points of equivalent H 2 efficiency improvement on conventional reforming. - Abstract: A detailed and comprehensive design of a H 2 production plant based on a novel Ca/Cu chemical looping process is presented in this work. This H 2 production process is based on the sorption-enhanced reforming concept using natural gas together with a CaO/CaCO 3 chemical loop. A second Cu/CuO loop is incorporated to supply energy for the calcination of the CaCO 3 via the reduction of CuO with a fuel gas. A comprehensive energy integration description of the different gas streams available in the plant is provided to allow a thermodynamic assessment of the process and to highlight its advantages and drawbacks. Hydrogen equivalent efficiencies of up to 77% are feasible with this novel Ca/Cu looping process, using an active reforming catalyst based on Pt, high oxidation temperatures and moderate gas velocities in the fixed bed system, which are around 6% points above the efficiency of a reference H 2 production plant based on conventional steam reforming including CO 2 capture with MDEA. Non-converted carbon compounds in the reforming stage are removed as CO 2 in the calcination stage of the Ca/Cu looping process, which will be compressed and sent for storage. Carbon capture efficiencies of around 94% can be obtained with this Ca/Cu looping process, which are significantly higher than those obtained in the reference plant that uses MDEA absorption (around 85%). Additional advantages, such as its compact design and the use of cheaper materials compared to other commercial processes for H 2 production with CO 2 capture, confirm the potential of the Ca

Analysis of energy cascade utilization in a chemically recuperated scramjet with indirect combustion

International Nuclear Information System (INIS)

Qin, Jiang; Cheng, Kunlin; Zhang, Silong; Zhang, Duo; Bao, Wen; Han, Jiecai

2016-01-01

The working process of scramjet with regenerative cooling, which was actually the chemical recuperation process, was analyzed in view of energy cascade utilization. The indirect combustion was realized through pyrolysis reaction of fuel. The relative yields of thermal exergy obtained by indirect combustion have been predicted both assuming an ideal pyrolysis reaction and using the experimental results of thermal pyrolysis of n-decane. The results showed that the influence mechanism of regenerative cooling improved the scramjet engine performance by the energy cascade utilization, and the combustion process was supposed to be designed with the cooling process together to utilize the chemical energy of fuel in a more effective way. A maximum value of 11% of the relative yield was obtained with the ideal pyrolysis reaction while a value less than 3% existed in the thermal pyrolysis experiments because of the domination of chemical kinetics rather than chemical thermodynamics in the real experiments. In spite of the difference between the ideal and the present experimental results, the indirect combustion was prospective to achieve a better energy cascade utilization in a chemically recuperated scramjet if the pyrolysis reaction was further optimized. The results in this paper were beneficial for the performance optimization of a regenerative cooling scramjet. - Highlights: • A new method of energy cascade utilization in a chemically recuperated scramjet. • 11% exergy loss is reduced by ideal pyrolysis reaction with indirect combustion. • Regenerative cooling with chemical recuperation can improve engine performance.

Theoretical study of stability and reaction mechanism of CuO supported on ZrO{sub 2} during chemical looping combustion

Energy Technology Data Exchange (ETDEWEB)

Wang, Minjun; Liu, Jing, E-mail: liujing27@mail.hust.edu.cn; Shen, Fenghua; Cheng, Hao; Dai, Jinxin; Long, Yan

2016-03-30

Graphical abstract: - Highlights: • The stability and reaction mechanism of CuO supported on ZrO{sub 2} were studied by DFT. • ZrO{sub 2} provides a high resistance to CuO sintering. • ZrO{sub 2} promotes the activity of CuO for CO oxidation in fuel reactor. • The energy barriers are low enough for CuO/ZrO{sub 2} oxidation reaction in air reactor. - Abstract: The addition of inert support is important for the Cu-based oxygen carrier used in chemical looping combustion (CLC). The effects of the ZrO{sub 2} support on the stability and reactivity of Cu-based oxygen carrier were investigated using the density functional theory (DFT). First, the sintering inhibition mechanism of ZrO{sub 2} that support active CuO was investigated. The optimized Cu{sub 4}O{sub 4}/ZrO{sub 2} structure showed a strong interaction occurred between the Cu{sub 4}O{sub 4} cluster and ZrO{sub 2}(1 0 1) surface. The interaction prevented the migration and agglomeration of CuO. Next, the adsorption of CO on Cu{sub 4}O{sub 4}/ZrO{sub 2} and the mechanism of the CuO/ZrO{sub 2} reduction by CO were studied. CO mainly chemisorbed on the Cu site and ZrO{sub 2} acted as an electron donor in the adsorption system. The energy barrier of CuO/ZrO{sub 2} reduction by CO (0.79 eV) was much lower than that of the pure CuO cluster (1.44 eV), indicating that ZrO{sub 2} had a positive effect on CuO/ZrO{sub 2} reduction by CO. After CO was oxidized in the fuel reactor, the CuO was reduced into Cu. The adsorption of O{sub 2} on Cu{sub 2}/ZrO{sub 2} and the most likely pathway of Cu{sub 2}/ZrO{sub 2} oxidation by O{sub 2} were investigated. The adsorption of O{sub 2} was found a strong chemisorption behavior. The energy barriers were low enough for the Cu-based oxygen carrier oxidation reaction.

The breakthrough of common rail system. Closed-loop control strategy using injector with built-in pressure sensor

Energy Technology Data Exchange (ETDEWEB)

Miyaki, Masahiko; Takeuchi, Katsuhiko; Ishizuka, Koji; Sasaki, Satoru [DENSO Corporation, Aichi-ken (Japan)

2009-07-01

DENSO has developed the world's first common rail system injector with built-in pressure sensor. This technology makes it possible to execute closed loop injection control in the cylinders, which has been one of the most challenging issues for diesel engine systems. Attaining both further fuel economy and emission reduction requires further technological innovation in the air system and fuel injection system. With the combustion technology that has been developed, stable combustion with high exhaust gas recirculation (EGR) is required in order to reduce nitrogen oxide's (NOx), however robustness is also required in order to handle bio-diesel and low-cetane value fuels and the range for attaining this is extremely narrow. Therefore, for the fuel injection system, in addition to conventional high pressure and high response, lifetime accuracy compensation is key. With this newly developed technology, the fuel injection rate, which determines the combustion within the engine cylinders, is directly detected and controlled in a closed loop to allow precise compensation of the injection system for its entire service life. Highly advanced injection control allows for extremely close multiple injections and variable injection rate control to be possible on the mass production level for the first time. Furthermore, the use of this technology can provide three major advantages for the overall engine system. Firstly succeeds in an expansion of the possible calibration range, which improves fuel economy and emissions, secondly it provides an improvement in the overall engine robustness and reliability. Thirdly, the use of closed loop control makes it possible to greatly reduce the man-hours required for calibration. Given this, the new DENSO common rail system using injectors with built-in pressure sensors is the first step to opening up a new era of diesel engine control. (orig.)

Investigation of hydrogen generation in a three reactor chemical looping reforming process

International Nuclear Information System (INIS)

Khan, Mohammed N.; Shamim, Tariq

2016-01-01

Highlights: • Three-reactor based chemical looping reforming system for hydrogen production. • Investigation of operating parameters using a system-level model. • Optimum operating conditions for hydrogen production are identified. • Different operating parameters affect the reactor temperatures differently. - Abstract: Chemical looping reforming (CLR) is a relatively new method to produce hydrogen (H_2) and is also used as an energy conversion method for solid, liquid or gaseous fuels. There are various advantages of this method such as inherent carbon dioxide (CO_2) capture, minimal NOx emissions and the H_2 production. In this process, there is no direct contact between the fuel and oxidizer. This method utilizes oxygen from an oxygen carrier which may be a transition metal. The idea is to split the combustion process into three separate sub-processes by employing three separate reactors: air reactor where the oxygen carrier is oxidized by air, fuel reactor where natural gas is oxidized to produce a stream of CO_2 and H_2O and steam reactor where the steam is reduced to produce H_2. In this study, a thermodynamic model with iron oxides as oxygen carrier has been developed using Aspen Plus by employing conservation of mass and energy for all the components of the CLR system. The developed model was employed to investigate the effect of various operating parameters such as mass flow rates of air, fuel, steam and oxygen carrier and fraction of inert material on H_2 and CO_2 production and key reactor temperatures. The results show that the H_2 production increases with the increase in air, fuel and steam flow rates up to a certain limit and stays constant for higher flow rates. The CO_2 production follows a similar trend. Similarly, the H_2 production also increases with the increase in oxide flow rate and fraction of inert material up to a particular value, but then decrease for higher oxide flow rates and inert fractions. Reactor temperatures were also

Chemical kinetics and combustion modelling with CFX 4

Energy Technology Data Exchange (ETDEWEB)

Stopford, P [AEA Technology, Computational Fluid Dynamics Services Harwell, Oxfordshire (United Kingdom)

1998-12-31

The presentation describes some recent developments in combustion and kinetics models used in the CFX software of AEA Technology. Three topics are highlighted: the development of coupled solvers in a traditional `SIMPLE`-based CFD code, the use of detailed chemical kinetics mechanism via `look-up` tables and the application of CFD to large-scale multi-burner combustion plant. The aim is identify those physical approximations and numerical methods that are likely to be most useful in the future and those areas where further developments are required. (author) 6 refs.

Chemical kinetics and combustion modelling with CFX 4

Energy Technology Data Exchange (ETDEWEB)

Stopford, P. [AEA Technology, Computational Fluid Dynamics Services Harwell, Oxfordshire (United Kingdom)

1997-12-31

The presentation describes some recent developments in combustion and kinetics models used in the CFX software of AEA Technology. Three topics are highlighted: the development of coupled solvers in a traditional `SIMPLE`-based CFD code, the use of detailed chemical kinetics mechanism via `look-up` tables and the application of CFD to large-scale multi-burner combustion plant. The aim is identify those physical approximations and numerical methods that are likely to be most useful in the future and those areas where further developments are required. (author) 6 refs.

Experimentelle Untersuchung des Chemical Looping Verfahrens an einer 1 MW Versuchsanlage

OpenAIRE

Orth, Matthias

2014-01-01

Im Zeichen des Klimawandels haben sich führende Industrienationen geeinigt, ihre jeweiligen CO2-Emissionen signifikant zu senken. Diese Reduktionsziele können nur erreicht werden, wenn die Emissionen bei der Energieerzeugung deutlich gesenkt werden. In der vorliegenden Arbeit wird das sogenannte Chemical Looping Verfahren untersucht, bei dem Energie aus fossilen Energieträgern gewonnen und das dabei entstehende CO2 abgeschieden wird. Die aktuelle Forschung im Bereich Chemical Looping konzentr...

Method for the combustion of a gas, in fixed bed, with an oxidized solid and associated installation

OpenAIRE

Abanades García, Juan Carlos; Fernández García, José Ramón

2014-01-01

[EN] The present invention pertains to the field of the generation of energy from combustible gases, incorporating the capture of carbon dioxide for use or permanent storage and, specifically relates to cyclical methods of gas combustion with oxidized solids (chemical looping processes), in fixed bed, for solving the problem of controlling temperature in the combustion of gaseous fuels in fixed beds of metal oxides operating at high pressures, and also the associated installation.

Chemical Looping Combustion with Different Types of Liquid Fuels Combustion en boucle chimique avec différentes charges liquides

Directory of Open Access Journals (Sweden)

Hoteit A.

2011-02-01

Full Text Available CLC is a new promising combustion process for CO2 capture with less or even no energy penalty compared to other processes. Up to now, most of the work performed on CLC was conducted with gaseous or solid fuels, using methane and coal and/or pet coke. Liquid fuels such as heavy fuels resulting from oil distillation or conversion may also be interesting feedstocks to consider. However, liquid fuels are challenging feedstock to deal with in fluidized beds. The objective of the present work is therefore to investigate the feasibility of liquid feed injection and contact with oxygen carrier in CLC conditions in order to conduct partial or complete combustion of hydrocarbons. A batch experimental fluidized bed set-up was developed to contact alternatively oxygen carrier with liquid fuels or air. The 20 mm i.d. fluidized bed reactor was filled up with 45 g of NiAl0.44O1.67 and pulses of 1-2 g of liquid were injected in the bed at high temperatures up to 950˚C. Different feedstocks have been injected, from dodecane to heavy fuel oils No.2. Results show that, during the reduction period, it is possible to convert all the fuel injected and there is no coke remaining on particles at the end of the reduction step. Depending upon oxygen available in the bed, either full combustion or partial combustion can be achieved. Similar results were found with different liquid feeds, despite their different composition and properties. Le CLC est un nouveau concept prometteur appliqué à la combustion qui permet le captage de CO en minimisant la pénalité énergétique liée au captage. Jusqu’à présent, l’essentiel des travaux de recherche dans le domaine du CLC concerne les charges gazeuses (méthane et solides (charbon et coke. Les charges liquides, et particulièrement les résidus pétroliers, sont des charges également intéressantes à considérer a priori. La mise en oeuvre de ces charges en lit fluidisé est cependant délicate. L’objet de ce

Chemical source characterization of residential wood combustion emissions in Denver, Colorado; Bakersfield, California; and Mammoth Lakes, California

International Nuclear Information System (INIS)

Houck, J.E.; Goulet, J.M.; Chow, J.C.; Watson, J.G.

1989-01-01

The chemical composition of residential wood combustion particulate emissions was determined for fireplaces and woodstoves. Burn rates, burn patterns, wood burning appliances, and cordwood types characteristic of Denver, Colorado; Bakersfield, California; and Mammoth Lakes, California, were used during sample collection. Samples were collected using a dilution/cooling system to ensure that condensible compounds were captured. Analyses for 44 chemical species were conducted. Source profiles for use in chemical mass balance (CMB) modeling were calculated from the analytical data. The principal chemical species comprising the profiles were organic compounds and elemental carbon. The minor chemical species were sulfur, chlorine, potassium, sodium, calcium, zinc, nitrate, and ammonium. Virtually all potassium was in a water-soluble form, and sulfur emissions between fireplaces and woodstoves were noted. Area-specific source profiles for fireplaces, woodstoves, and overall residential wood combustion are presented

Solar chemical heat pipe in a closed loop

International Nuclear Information System (INIS)

Levy, M.

1990-06-01

The work on the solar CO 2 reforming of methane was completed. A computer program was developed for simulation of the whole process. The calculations agree reasonably well with the experimental results. The work was written up and submitted for publication in Solar Energy. A methanator was built and tested first with a CO/H 2 mixture from cylinders, and then with the products of the solar reformer. The loop was then closed by recirculating the products from the methanator into the solar reformer. Nine closed loop cycles were performed, so far, with the same original gas mixture. This is the first time that a closed loop solar chemical heat pipe was operated anywhere in the world. (author). 13 refs., 12 figs., 3 tabs

Establishment of Combustion Model for Isooctane HCCI Marine Diesel Engine and Research on the Combustion Characteristic

Directory of Open Access Journals (Sweden)

Li Biao

2016-01-01

Full Text Available The homogeneous charge compression ignition (HCCI combustion mode applied in marine diesel engine is expected to be one of alternative technologies to decrease nitrogen oxide (NOX emission and improve energy utilization rate. Applying the chemical-looping combustion (CLC mechanism inside the cylinder, a numerical study on the HCCI combustion process is performed taking a marine diesel engine as application object. The characteristic feature of combustion process is displayed. On this basis, the formation and emission of NOX are analyzed and discussed. The results indicate that the HCCI combustion mode always exhibit two combustion releasing heats: low-temperature reaction and high-temperature reaction. The combustion phase is divided into low-temperature reaction zone, high-temperature reaction zone and negative temperature coefficient (NTC zone. The operating conditions of the high compression ratio, high intake air temperature, low inlet pressure and small excess air coefficient would cause the high in-cylinder pressure which often leads engine detonation. The low compression ratio, low intake air temperature and big excess air coefficient would cause the low combustor temperature which is conducive to reduce NOX emissions. These technological means and operating conditions are expected to meet the NOX emissions limits in MARPOL73/78 Convention-Annex VI Amendment.

Establishment of an Environmental Control Technology Laboratory with a Circulating Fluidized-Bed Combustion System

Energy Technology Data Exchange (ETDEWEB)

Wei-Ping Pan; Yan Cao; John Smith

2008-05-31

particulate filtration technologies. Major tasks during this period of the funded project's timeframe included: (1) Conducting pretests on a laboratory-scale simulated FBC system; (2) Completing detailed design of the bench-scale CFBC system; (3) Contracting potential bidders to fabricate of the component parts of CFBC system; (4) Assembling CFBC parts and integrating system; (5) Resolving problems identified during pretests; (6) Testing with available Powder River Basin (PRB) coal and co-firing of PRB coal with first wood pallet and then chicken wastes; and (7) Tuning of CFBC load. Following construction system and start-up of this 0.6 MW CFBC system, a variety of combustion tests using a wide range of fuels (high-sulfur coals, low-rank coals, MSW, agricultural waste, and RDF) under varying conditions were performed to analyze and monitor air pollutant emissions. Data for atmospheric pollutants and the methodologies required to reduce pollutant emissions were provided. Integration with a selective catalytic reduction (SCR) slipstream unit did mimic the effect of flue gas composition, including trace metals, on the performance of the SCR catalyst to be investigated. In addition, the following activities were also conducted: (1) Developed advanced mercury oxidant and adsorption additives; (2) Performed laboratory-scale tests on oxygen-fuel combustion and chemical looping combustion; and (3) Conducted statistical analysis of mercury emissions in a full-scale CFBC system.

Enhancement of exergy efficiency in combustion systems using flameless mode

International Nuclear Information System (INIS)

Hosseini, Seyed Ehsan; Wahid, Mazlan Abdul

2014-01-01

Highlights: • Exergy efficiency in flameless combustion mode is 13% more than conventional combustion. • The maximum exergy efficiency in flameless combustion mode is achieved when oxidizer contains 10% oxygen. • Exergy destruction of flameless combustion is maximized when CO 2 is used for dilution of oxidizer. - Abstract: An exergitic-based analysis of methane (CH 4 ) conventional and flameless combustion in a lab-scale furnace is performed to determine the rate of pollutant formation and the effective potential of a given amount of fuel in the various combustion modes. The effects of inlet air temperature on exergy efficiency and pollutant formation of conventional combustion in various equivalence ratios are analyzed. The rate of exergy destruction in different conditions of flameless combustion (various equivalence ratios, oxygen concentration in the oxidizer and the effects of diluent) are computed using three-dimensional (3D) computational fluid dynamic (CFD). Fuel consumption reduction and exergy efficiency augmentation are the main positive consequences of using preheated air temperature in conventional combustion, however pollutants especially NO x formation increases dramatically. Low and moderate temperature inside the chamber conducts the flameless combustion system to low level pollutant formation. Fuel consumption and exergy destruction reduce drastically in flameless mode in comparison with conventional combustion. Exergy efficiency of conventional and flameless mode is 75% and 88% respectively in stoichiometric combustion. When CO 2 is used for dilution of oxidizer, chemical exergy increases due to high CO 2 concentration in the combustion products and exergy efficiency reduces around 2% compared to dilution with nitrogen (N 2 ). Since the rate of irreversibilities in combustion systems is very high in combined heat and power (CHP) generation and other industries, application of flameless combustion could be effective in terms of pollutant

Chemical Looping Combustion of Solid Fuels in a 10 kWth Unit Combustion de charge solide en boucle chimique dans une unité de 10 kWth

Directory of Open Access Journals (Sweden)

Berguerand N.

2011-02-01

Full Text Available The present study is based on previous results from batch experiments which were conducted in a 10 kWth chemical looping combustor for solid fuels using ilmenite, an iron titanium oxide, as the oxygen carrier with two solid fuels: a Mexican petroleum coke and a South African bituminous coal. These experiments involved testing at different fuel reactor temperatures, up to 1030°C, and different particle circulation rates between the air and fuel reactors. Previous results enabled modeling of the reactor system. In particular, it was possible to derive a correlation between measured operational data and actual circulation mass flow, as well as a model that describes the carbon capture efficiency as a function of the residence time and the char reactivity. Moreover, the kinetics of char conversion could be modeled and results showed good agreement with experimental values. The purpose of the present study was to complete these results by developing a model to predict the conversion of syngas with ilmenite in the fuel reactor. Here, kinetic data from investigations of ilmenite in TGA and batch fluidized bed reactors were used. Results were compared with the actual conversions during operation in this 10 kWth unit. Cette étude est basée sur des résultats antérieurs obtenus dans une unité de combustion de charges solides en boucle chimique d’une puissance de 10 kWth. Le transporteur d’oxygène utilisé est de l’ilménite, un minerai de fer et de titane, et les charges solides étudiées sont, d’une part, un coke de pétrole mexicain et, d’autre part, un charbon bitumineux sud africain. Les résultats expérimentaux ont été obtenus à des températures allant jusqu’à 1030°C avec différents débits de transporteur d’oxygène entre les réacteurs d’oxydation et de réduction. La modélisation de la combustion en boucle chimique de charges solides a déjà permis d’établir une corrélation entre le débit de circulation de

Effect of Ash on Oxygen Carriers for the Application of Chemical Looping Combustion to a High Carbon Char Effet des cendres sur l’activité des porteurs d’oxygène dans la combustion du charbon en boucle chimique

Directory of Open Access Journals (Sweden)

Rubel A.

2011-02-01

Full Text Available The application of Chemical Looping Combustion (CLC to solid fuels is being investigated at the University of Kentucky, Center for Applied Energy Research (CAER with the aim of the development of a Pressurized Chemical Looping Combustion/Gasification (PCLC/G process for the generation of electricity from coal. One important aspect of the CLC of solid fuel is the understanding of the effect of ash on the reactivity of Oxygen Carriers (OCs. The effect of ash on the redox capabilities of two different iron oxide OCs and on their ability to oxidize coal char was studied. To determine the effect of ash on the reactivity and recycle of the OCs through multiple redox cycles, fly ash from a coal-fired power plant was used. These experiments were performed in a TGMS system using 500 mg of ash/OC mixtures containing different ash concentrations up to 75%. The reducing gas was composed of 10% H2, 15% CO, 20% CO2, and a balance of Ar and the oxidizing gas was 20% O2 in Ar. Oxidation/reductions were carried to near completion. The ash was found to contain OC activity related to inherent iron present in the ash confirmed by XRD. This resulted in increased weight gain/loss on oxidation/reduction. The rate of oxidation/reduction increased with ash concentration due to increased porosity of the OC/ash mixture and better access of the reactive gases to the OC target sites. The two OCs were then used to combust a beneficiated coal char in the TGMS with the only oxygen supplied by an iron oxide OC. The starting mixture was 10% char and 90% of one of two OCs studied. The spent material containing reduced OC and ash was re-oxidized and 10% more char was added for a second reduction of the OC and oxidation of the added char. This procedure was repeated for 5 cycles increasing the ash concentrations from 5 to 25% in the char/ash/OC mixture. Carbon removal was 92 to 97.8 and 97.3 to 99.7% for the two different iron oxide OCs tested. Ash was not detrimental to the

Chemical Kinetic Models for Advanced Engine Combustion

Energy Technology Data Exchange (ETDEWEB)

Pitz, William J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mehl, Marco [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Westbrook, Charles K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2014-10-22

The objectives for this project are as follows: Develop detailed chemical kinetic models for fuel components used in surrogate fuels for compression ignition (CI), homogeneous charge compression ignition (HCCI) and reactivity-controlled compression-ignition (RCCI) engines; and Combine component models into surrogate fuel models to represent real transportation fuels. Use them to model low-temperature combustion strategies in HCCI, RCCI, and CI engines that lead to low emissions and high efficiency.

Environmental impacts of open loop geothermal system on groundwater

Science.gov (United States)

Kwon, Koo-Sang; Park, Youngyun; Yun, Sang Woong; Lee, Jin-Yong

2013-04-01

Application of renewable energies such as sunlight, wind, rain, tides, waves and geothermal heat has gradually increased to reduce emission of CO2 which is supplied from combustion of fossil fuel. The geothermal energy of various renewable energies has benefit to be used to cooling and heating systems and has good energy efficiency compared with other renewable energies. However, open loop system of geothermal heat pump system has possibility that various environmental problems are induced because the system directly uses groundwater to exchange heat. This study was performed to collect data from many documents such as papers and reports and to summarize environmental impacts for application of open loop system. The environmental impacts are classified into change of hydrogeological factors such as water temperature, redox condition, EC, change of microbial species, well contamination and depletion of groundwater. The change of hydrogeological factors can induce new geological processes such as dissolution and precipitation of some minerals. For examples, increase of water temperature can change pH and Eh. These variations can change saturation index of some minerals. Therefore, dissolution and precipitation of some minerals such as quartz and carbonate species and compounds including Fe and Mn can induce a collapse and a clogging of well. The well contamination and depletion of groundwater can reduce available groundwater resources. These environmental impacts will be different in each region because hydrogeological properties and scale, operation period and kind of the system. Therefore, appropriate responses will be considered for each environmental impact. Also, sufficient study will be conducted to reduce the environmental impacts and to improve geothermal energy efficiency during the period that a open loop system is operated. This work was supported by the Energy Efficiency and Resources of the Korea Institute of Energy Technology Evaluation and Planning

Modelling of EAF off-gas post combustion in dedusting systems using CFD methods

Energy Technology Data Exchange (ETDEWEB)

Tang, X.; Kirschen, M.; Pfeifer, H. [Inst. for Industrial Furnaces and Heat Engineering in Metallurgy, RWTH Aachen, Aachen (Germany); Abel, M. [VAI-Fuchs GmbH, Willstaett (Germany)

2003-04-01

To comply with the increasingly strict environmental regulations, the poisonous off-gas species, e.g. carbon monoxide (CO), produced in the electric arc furnace (EAF) must be treated in the dedusting system. In this work, gas flow patterns of the off-gas post combustion in three different dedusting system units were simulated with a computational fluid dynamics (CFD) code: (1) post combustion in a horizontal off-gas duct, (2) post combustion in a water cooled post combustion chamber without additional energy supply (no gas or air/oxygen injectors) and (3) post combustion in a post combustion chamber with additional energy input (gas, air injectors and ignition burner, case study of VAI-Fuchs GmbH). All computational results are illustrated with gas velocity, temperature distribution and chemical species concentration fields for the above three cases. In case 1, the effect of different false air volume flow rates at the gap between EAF elbow and exhaust gas duct on the external post combustion of the off-gas was investigated. For case 2, the computed temperature and chemical composition (CO, CO{sub 2} and O{sub 2}) of the off-gas at the post chamber exit are in good agreement with additional measurements. Various operating conditions for case 3 have been studied, including different EAF off-gas temperatures and compositions, i. e. CO content, in order to optimize oxygen and burner gas flow rates. Residence time distributions in the external post combustion chambers have been calculated for cases 2 and 3. Derived temperature fields of the water cooled walls yield valuable information on thermally stressed parts of post combustion units. The results obtained in this work may also gain insight to future investigation of combustion of volatile organic components (VOC) or formation of nitrogen oxide (NO{sub x}) and permit the optimization of the operation and design of the off-gas dedusting system units. (orig.)

Combustion engineering

CERN Document Server

Ragland, Kenneth W

2011-01-01

Introduction to Combustion Engineering The Nature of Combustion Combustion Emissions Global Climate Change Sustainability World Energy Production Structure of the Book   Section I: Basic Concepts Fuels Gaseous Fuels Liquid Fuels Solid Fuels Problems Thermodynamics of Combustion Review of First Law Concepts Properties of Mixtures Combustion StoichiometryChemical EnergyChemical EquilibriumAdiabatic Flame TemperatureChemical Kinetics of CombustionElementary ReactionsChain ReactionsGlobal ReactionsNitric Oxide KineticsReactions at a Solid SurfaceProblemsReferences  Section II: Combustion of Gaseous and Vaporized FuelsFlamesLaminar Premixed FlamesLaminar Flame TheoryTurbulent Premixed FlamesExplosion LimitsDiffusion FlamesGas-Fired Furnaces and BoilersEnergy Balance and EfficiencyFuel SubstitutionResidential Gas BurnersIndustrial Gas BurnersUtility Gas BurnersLow Swirl Gas BurnersPremixed-Charge Engine CombustionIntroduction to the Spark Ignition EngineEngine EfficiencyOne-Zone Model of Combustion in a Piston-...

Design of a rotary reactor for chemical-looping combustion. Part 2: Comparison of copper-, nickel-, and iron-based oxygen carriers

KAUST Repository

Zhao, Zhenlong

2014-04-01

Chemical-looping combustion (CLC) is a novel and promising option for several applications including carbon capture (CC), fuel reforming, H 2 generation, etc. Previous studies demonstrated the feasibility of performing CLC in a novel rotary design with micro-channel structures. Part 1 of this series studied the fundamentals of the reactor design and proposed a comprehensive design procedure, enabling a systematic methodology of designing and evaluating the rotary CLC reactor with different OCs and operating conditions. This paper presents the application of the methodology to the designs with three commonly used OCs, i.e., copper, nickel, and iron. The physical properties and the reactivities of the three OCs are compared at operating conditions suitable for the rotary CLC. Nickel has the highest reduction rate, but relatively slow oxidation reactivity while the iron reduction rate is most sensitive to the fuel concentration. The design parameters and the operating conditions for the three OCs are selected, following the strategies proposed in Part 1, and the performances are evaluated using a one-dimensional plug-flow model developed previously. The simulations show that for all OCs, complete fuel conversion and high carbon separation efficiency can be achieved at periodic stationary state with reasonable operational stabilities. The nickel-based design includes the smallest dimensions because of its fast reduction rate. The operation of nickel case is mainly limited to the slow oxidation rate, and hence a relatively large share of air sector is used. The iron-based design has the largest size, due to its slow reduction reactivity near the exit or in the fuel purge sector where the fuel concentration is low. The gas flow temperature increases monotonically for all the cases, and is mainly determined by the solid temperature. In the periodic state, the local temperature variation is within 40 K and the thermal distortion is limited. The design of the rotary CLC is

System and method for conditioning intake air to an internal combustion engine

Science.gov (United States)

Sellnau, Mark C.

2015-08-04

A system for conditioning the intake air to an internal combustion engine includes a means to boost the pressure of the intake air to the engine and a liquid cooled charge air cooler disposed between the output of the boost means and the charge air intake of the engine. Valves in the coolant system can be actuated so as to define a first configuration in which engine cooling is performed by coolant circulating in a first coolant loop at one temperature, and charge air cooling is performed by coolant flowing in a second coolant loop at a lower temperature. The valves can be actuated so as to define a second configuration in which coolant that has flowed through the engine can be routed through the charge air cooler. The temperature of intake air to the engine can be controlled over a wide range of engine operation.

Low Temperature Combustion Demonstrator for High Efficiency Clean Combustion

Energy Technology Data Exchange (ETDEWEB)

Ojeda, William de

2010-07-31

The project which extended from November 2005 to May of 2010 demonstrated the application of Low Temperature Combustion (LTC) with engine out NOx levels of 0.2 g/bhp-hr throughout the program target load of 12.6bar BMEP. The project showed that the range of loads could be extended to 16.5bar BMEP, therefore matching the reference lug line of the base 2007 MY Navistar 6.4L V8 engine. Results showed that the application of LTC provided a dramatic improvement over engine out emissions when compared to the base engine. Furthermore LTC improved thermal efficiency by over 5% from the base production engine when using the steady state 13 mode composite test as a benchmark. The key enablers included improvements in the air, fuel injection, and cooling systems made in Phases I and II. The outcome was the product of a careful integration of each component under an intelligent control system. The engine hardware provided the conditions to support LTC and the controller provided the necessary robustness for a stable combustion. Phase III provided a detailed account on the injection strategy used to meet the high load requirements. During this phase, the control strategy was implemented in a production automotive grade ECU to perform cycle-by-cycle combustion feedback on each of the engine cylinders. The control interacted on a cycle base with the injection system and with the Turbo-EGR systems according to their respective time constants. The result was a unique system that could, first, help optimize the combustion system and maintain high efficiency, and secondly, extend the steady state results to the transient mode of operation. The engine was upgraded in Phase IV with a Variable Valve Actuation system and a hybrid EGR loop. The impact of the more versatile EGR loop did not provide significant advantages, however the application of VVA proved to be an enabler to further extend the operation of LTC and gain considerable benefits in fuel economy and soot reduction. Finally

Oxidation and Reduction of Iron-Titanium Oxides in Chemical Looping Combustion: A Phase-Chemical Description Oxydation et réduction des minerais de fer-titane dans la combustion en boucle chimique

Directory of Open Access Journals (Sweden)

den Hoed P.

2011-05-01

Full Text Available Ilmenite (FeTiO3 is being explored as an oxygen carrier in chemical looping processes. Its reduction and oxidation are described by the system Fe-Fe2O3-TiO2-Ti2O3. The phase diagram at 1 000°C, presented here, offers a useful tool for predicting reactions and their products. We see that Fe2TiO5 (pseudobrookite and TiO2 (rutile form a stable phase assemblage following the oxidation of FeTiO3 (ilmenite in air. The subsequent reduction of Fe2TiO5 at oxygen partial pressures of 10-15.5atm stabilizes Fe1.02Ti0.98O3, a solid solution of ilmenite. Further reduction will produce metallic iron, which compromises the integrity of the oxygen carrier for chemical looping processes. We speculate that the reduction of Fe-Ti oxides in several practical instances does not reach completion (and equilibrium under the imposed atmospheres operating in fuel reactors. L’ilménite (FeTiO3 est considéré comme un transporteur d’oxygène potentiel pour les procédés en boucle chimique. Ses mécanismes de réduction et d’oxydation sont décrits à travers le système Fe-Fe2O3-TiO2-TiO3. Le diagramme de phase à 1 000°C, présenté ici, est un outil utile pour prédire les réactions et les produits. Nous constatons que Fe2TiO5 (pseudobrookite et TiO2 (rutile forment un assemblage de phase stable après oxydation de l’ilménite (FeTiO3 dans l’air. La réduction subséquente de Fe2TiO5 à la pression partielle de 10−15,5atm stabilise vers Fe1.02Ti0.98O3, une solution solide d’ilménite. Une réduction plus poussée va produire du fer métallique et compromettre l’intégrité du transporteur d’oxygène dans la boucle chimique. Il est probable que la réduction des oxydes Fe-Ti ne soit pas, en pratique, complète et n’atteigne pas l’équilibre dans les conditions rencontrées en opération dans les réacteurs de réduction.

Use of catalytic reforming to aid natural gas HCCI combustion in engines: experimental and modelling results of open-loop fuel reforming

Energy Technology Data Exchange (ETDEWEB)

Peucheret, S.; Wyszynski, M.L.; Lehrle, R.S. [Future Power Systems Group, Mechanical Engineering, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Golunski, S. [Johnson Matthey, Technology Centre, Blount' s Court, Sonning Common, Reading RG4 9NH (United Kingdom); Xu, H. [Jaguar Land Rover Research, Jaguar Land Rover W/2/021, Abbey Road, Coventry CV3 4LF (United Kingdom)

2005-12-01

The potential of the homogeneous charge compression ignition (HCCI) combustion process to deliver drastically reduced emissions of NO{sub x} and improved fuel economy from internal combustion engines is well known. The process is, however, difficult to initiate and control, especially when methane or natural gas are used as fuel. To aid the HCCI combustion of natural gas, hydrogen addition has been successfully used in this study. This hydrogen can be obtained from on-line reforming of natural gas. Methane reforming is achieved here by reaction with engine exhaust gas and air in a small scale monolith catalytic reactor. The benchmark quantity of H{sub 2} required to enhance the feasibility and engine load range of HCCI combustion is 10%. For low temperature engine exhaust gas, typical for HCCI engine operating conditions, experiments show that additional air is needed to produce this quantity. Experimental results from an open-loop fuel exhaust gas reforming system are compared with two different models of basic thermodynamic equilibria calculations. At the low reactor inlet temperatures needed for the HCCI application (approx. 400 deg C) the simplified three-reaction thermodynamic equilibrium model is in broad agreement with experimental results, while for medium (550-650 deg C) inlet temperature reforming with extra air added, the high hydrogen yields predicted from the multi-component equilibrium model are difficult to achieve in a practical reformer. (author)

Combustion

CERN Document Server

Glassman, Irvin

1987-01-01

Combustion, Second Edition focuses on the underlying principles of combustion and covers topics ranging from chemical thermodynamics and flame temperatures to chemical kinetics, detonation, ignition, and oxidation characteristics of fuels. Diffusion flames, flame phenomena in premixed combustible gases, and combustion of nonvolatile fuels are also discussed. This book consists of nine chapters and begins by introducing the reader to heats of reaction and formation, free energy and the equilibrium constants, and flame temperature calculations. The next chapter explores the rates of reactio

The Physical/Chemical Closed-Loop Life Support Research Project

Science.gov (United States)

Bilardo, Vincent J., Jr.

1990-01-01

The various elements of the Physical/Chemical Closed-Loop Life Support Research Project (P/C CLLS) are described including both those currently funded and those planned for implementation at ARC and other participating NASA field centers. The plan addresses the entire range of regenerative life support for Space Exploration Initiative mission needs, and focuses initially on achieving technology readiness for the Initial Lunar Outpost by 1995-97. Project elements include water reclamation, air revitalization, solid waste management, thermal and systems control, and systems integration. Current analysis estimates that each occupant of a space habitat will require a total of 32 kg/day of supplies to live and operate comfortably, while an ideal P/C CLLS system capable of 100 percent reclamation of air and water, but excluding recycling of solid wastes or foods, will reduce this requirement to 3.4 kg/day.

The pyrolysis and combustion characteristics of five typical biomass from Tibet

Energy Technology Data Exchange (ETDEWEB)

Dong, C.Q.; Shan, L.; Yang, Y.P.; Zhang, J.J. [Ministry of Education, Beijing (China). Key Laboratory of Condition Monitoring and Control for Power Plant Equipment; North China Electric Power Univ., Beijing (China). Key Laboratory of Security and Clean Energy Technology

2008-07-01

Thermogravimetric (TG) and differential thermal gravimetric (DTG) methods were used to conduct pyrolysis and combustion tests of winter wheat, highland barley, sawdust, cattle manure, and sheep manure from Tibet. The aim of the study was to determine the combustion characteristics of biomass grown in regions with lower levels of atmospheric oxygen. A reaction kinetic model was used to determine kinetic parameters of the biomass samples. The study showed that oxygen concentrations did not influence activation energy. Combustion efficiency was influenced by the nitrogen dilute effect located in Tibet. The sawdust combustion analysis demonstrated that heat losses from flue gases were approximately 5 per cent higher when oxygen levels were 11 per cent, than when oxygen levels were 21 per cent. It was concluded that chemical looping processes can be used to improve efficiency and reduce the environmental impacts associated with biomass combustion in Tibet. 17 refs., 3 tabs., 6 figs.

Effects of combustion efficiency on a Dual cycle

International Nuclear Information System (INIS)

Ozsoysal, Osman Azmi

2009-01-01

This paper studies a Dual cycle model containing irreversibilities coming exclusively from expansion and compression processes. It is assumed that any fraction of the fuel's chemical energy can not fully released inside the engine because of the incomplete combustion. Utilizing the combustion efficiency is found to be more useful to realize the cycle feasibility. Amount of the released energy from fuel into the cylinder restricts the compression ratio. It is presented how the upper limit of compression ratio is evaluated by means of using some constraints for realizing a Dual cycle. Valid ranges of the constraints given in literature seriously affect the feasibility of cycle. Developed mathematical model leads to a qualitative understanding of how engine loss can be reduced. Thermal efficiency-work curves cannot have a closed loop shape because there is a close relationship between the fuel energy, air-fuel mass ratio, combustion efficiency, maximum cycle temperature and the heat losses into the cylinder wall. If these are all omitted, while heat losses are determined independently without establishing any relationship between the released fuel energy, the thermal efficiency versus work curves will just be able to have a closed loop shape. This is the original perspective and contribution of paper.

Development and validation of double and single Wiebe function for multi-injection mode Diesel engine combustion modelling for hardware-in-the-loop applications

International Nuclear Information System (INIS)

Maroteaux, Fadila; Saad, Charbel; Aubertin, Fabrice

2015-01-01

Highlights: • Modelling of Diesel engine combustion with multi-injection mode was conducted. • Double and single Wiebe correlations for pilot, main and post combustion processes were calibrated. • Ignition delay time correlations have been developed and calibrated using experimental data for each injection. • The complete in-cylinder model has been applied successfully to real time simulations on HiL test bed. - Abstract: The improvement of Diesel engine performances in terms of fuel consumption and pollutant emissions has a huge impact on management system and diagnostic procedure. Validation and testing of engine performances can benefit from the use of theoretical models, for the reduction of development time and costs. Hardware in the Loop (HiL) test bench is a suitable way to achieve these objectives. However, the increasing complexity of management systems rises challenges for the development of very reduced physical models able to run in real time applications. This paper presents an extension of a previously developed phenomenological Diesel combustion model suitable for real time applications on a HiL test bench. In the earlier study, the modelling efforts have been targeted at high engine speeds with a very short computational time window, and where the engine operates with single injection. In the present work, a modelling of in-cylinder processes at low and medium engine speeds with multi-injection is performed. In order to reach an adequate computational time, the combustion progress during the pilot and main injection periods has been treated through a double Wiebe function, while the post combustion period has required a single Wiebe function. This paper describes the basic system models and their calibration and validation against experimental data. The use of the developed correlations of Wiebe coefficients and ignition delay times for each combustion phase, included in the in-cylinder crank angle global model, is applied for the prediction

Comparison of Iron and Tungsten Based Oxygen Carriers for Hydrogen Production Using Chemical Looping Reforming

Science.gov (United States)

Khan, M. N.; Shamim, T.

2017-08-01

Hydrogen production by using a three reactor chemical looping reforming (TRCLR) technology is an innovative and attractive process. Fossil fuels such as methane are the feedstocks used. This process is similar to a conventional steam-methane reforming but occurs in three steps utilizing an oxygen carrier. As the oxygen carrier plays an important role, its selection should be done carefully. In this study, two oxygen carrier materials of base metal iron (Fe) and tungsten (W) are analysed using a thermodynamic model of a three reactor chemical looping reforming plant in Aspen plus. The results indicate that iron oxide has moderate oxygen carrying capacity and is cheaper since it is abundantly available. In terms of hydrogen production efficiency, tungsten oxide gives 4% better efficiency than iron oxide. While in terms of electrical power efficiency, iron oxide gives 4.6% better results than tungsten oxide. Overall, a TRCLR system with iron oxide is 2.6% more efficient and is cost effective than the TRCLR system with tungsten oxide.

New class of combustion processes

International Nuclear Information System (INIS)

Merzhanov, A.G.; Borovinskaya, I.P.

1975-01-01

A short review is given of the results of work carried out since 1967 on studying the combustion processes caused by the interaction of chemical elements in the condensed phase and leading to the formation of refractory compounds. New phenomena and processes are described which are revealed when investigating the combustion of the systems of this class, viz solid-phase combustion, fast combustion in the condensed phase, filtering combustion, combustion in liquid nitrogen, spinning combustion, self-oscillating combustion, and repeated combustion. A new direction in employment of combustion processes is discussed, viz. a self-propagating high-temperature synthesis of refractory nitrides, carbides, borides, silicides and other compounds

Energetic study of combustion instabilities and genetic optimisation of chemical kinetics; Etude energetique des instabilites thermo-acoustiques et optimisation genetique des cinetiques reduites

Energy Technology Data Exchange (ETDEWEB)

Martin, Ch.E.

2005-12-15

Gas turbine burners are now widely operated in lean premixed combustion mode. This technology has been introduced in order to limit pollutants emissions (especially the NO{sub x}), and thus comply with environment norms. Nevertheless, the use of lean premixed combustion decreases the stability margin of the flames. The flames are then more prone to be disturbed by flow disturbances. Combustion instabilities are then a major problem of concern for modern gas turbine conception. Some active control systems have been used to ensure stability of gas turbines retro-fitted to lean premixed combustion. The current generation of gas turbines aims to get rid of these control devices getting stability by a proper design. To do so, precise and adapted numerical tools are needed even it is impossible at the moment to guarantee the absolute stability of a combustion chamber at the design stage. Simulation tools for unsteady combustion are now able to compute the whole combustion chamber. Its intrinsic precision, allows the Large Eddy Simulation (LES) to take into account numerous phenomena involved in combustion instabilities. Chemical modelling is an important element for the precision of reactive LES. This study includes the description of an optimisation tools for the reduced chemical kinetics. The capacity of the LES to capture combustion instabilities in gas turbine chamber is also demonstrated. The acoustic energy analysis points out that the boundary impedances of the combustion systems are of prime importance for their stability. (author)

Multiple Flow Loop SCADA System Implemented on the Production Prototype Loop

Energy Technology Data Exchange (ETDEWEB)

Baily, Scott A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalmas, Dale Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wheat, Robert Mitchell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Woloshun, Keith Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-11-16

The following report covers FY 15 activities to develop supervisory control and data acquisition (SCADA) system for the Northstar Moly99 production prototype gas flow loop. The goal of this effort is to expand the existing system to include a second flow loop with a larger production-sized blower. Besides testing the larger blower, this system will demonstrate the scalability of our solution to multiple flow loops.

CloudFlame: Cyberinfrastructure for combustion research

KAUST Repository

Goteng, Gokop

2013-12-01

Combustion experiments and chemical kinetics simulations generate huge data that is computationally and data intensive. A cloud-based cyber infrastructure known as Cloud Flame is implemented to improve the computational efficiency, scalability and availability of data for combustion research. The architecture consists of an application layer, a communication layer and distributed cloud servers running in a mix environment of Windows, Macintosh and Linux systems. The application layer runs software such as CHEMKIN modeling application. The communication layer provides secure transfer/archive of kinetic, thermodynamic, transport and gas surface data using private/public keys between clients and cloud servers. A robust XML schema based on the Process Informatics Model (Prime) combined with a workflow methodology for digitizing, verifying and uploading data from scientific graphs/tables to Prime is implemented for chemical molecular structures of compounds. The outcome of using this system by combustion researchers at King Abdullah University of Science and Technology (KAUST) Clean Combustion Research Center and its collaborating partners indicated a significant improvement in efficiency in terms of speed of chemical kinetics and accuracy in searching for the right chemical kinetic data.

Perturbative study of the QCD phase diagram for heavy quarks at nonzero chemical potential: Two-loop corrections

Science.gov (United States)

Maelger, J.; Reinosa, U.; Serreau, J.

2018-04-01

We extend a previous investigation [U. Reinosa et al., Phys. Rev. D 92, 025021 (2015), 10.1103/PhysRevD.92.025021] of the QCD phase diagram with heavy quarks in the context of background field methods by including the two-loop corrections to the background field effective potential. The nonperturbative dynamics in the pure-gauge sector is modeled by a phenomenological gluon mass term in the Landau-DeWitt gauge-fixed action, which results in an improved perturbative expansion. We investigate the phase diagram at nonzero temperature and (real or imaginary) chemical potential. Two-loop corrections yield an improved agreement with lattice data as compared to the leading-order results. We also compare with the results of nonperturbative continuum approaches. We further study the equation of state as well as the thermodynamic stability of the system at two-loop order. Finally, using simple thermodynamic arguments, we show that the behavior of the Polyakov loops as functions of the chemical potential complies with their interpretation in terms of quark and antiquark free energies.

Spectral modeling of radiation in combustion systems

Science.gov (United States)

Pal, Gopalendu

Radiation calculations are important in combustion due to the high temperatures encountered but has not been studied in sufficient detail in the case of turbulent flames. Radiation calculations for such problems require accurate, robust, and computationally efficient models for the solution of radiative transfer equation (RTE), and spectral properties of radiation. One more layer of complexity is added in predicting the overall heat transfer in turbulent combustion systems due to nonlinear interactions between turbulent fluctuations and radiation. The present work is aimed at the development of finite volume-based high-accuracy thermal radiation modeling, including spectral radiation properties in order to accurately capture turbulence-radiation interactions (TRI) and predict heat transfer in turbulent combustion systems correctly and efficiently. The turbulent fluctuations of temperature and chemical species concentrations have strong effects on spectral radiative intensities, and TRI create a closure problem when the governing partial differential equations are averaged. Recently, several approaches have been proposed to take TRI into account. Among these attempts the most promising approaches are the probability density function (PDF) methods, which can treat nonlinear coupling between turbulence and radiative emission exactly, i.e., "emission TRI". The basic idea of the PDF method is to treat physical variables as random variables and to solve the PDF transport equation stochastically. The actual reacting flow field is represented by a large number of discrete stochastic particles each carrying their own random variable values and evolving with time. The mean value of any function of those random variables, such as the chemical source term, can be evaluated exactly by taking the ensemble average of particles. The local emission term belongs to this class and thus, can be evaluated directly and exactly from particle ensembles. However, the local absorption term

An optimized chemical kinetic mechanism for HCCI combustion of PRFs using multi-zone model and genetic algorithm

International Nuclear Information System (INIS)

Neshat, Elaheh; Saray, Rahim Khoshbakhti

2015-01-01

Highlights: • A new chemical kinetic mechanism for PRFs HCCI combustion is developed. • New mechanism optimization is performed using genetic algorithm and multi-zone model. • Engine-related combustion and performance parameters are predicted accurately. • Engine unburned HC and CO emissions are predicted by the model properly. - Abstract: Development of comprehensive chemical kinetic mechanisms is required for HCCI combustion and emissions prediction to be used in engine development. The main purpose of this study is development of a new chemical kinetic mechanism for primary reference fuels (PRFs) HCCI combustion, which can be applied to combustion models to predict in-cylinder pressure and exhaust CO and UHC emissions, accurately. Hence, a multi-zone model is developed for HCCI engine simulation. Two semi-detailed chemical kinetic mechanisms those are suitable for premixed combustion are used for n-heptane and iso-octane HCCI combustion simulation. The iso-octane mechanism contains 84 species and 484 reactions and the n-heptane mechanism contains 57 species and 296 reactions. A simple interaction between iso-octane and n-heptane is considered in new mechanism. The multi-zone model is validated using experimental data for pure n-heptane and iso-octane. A new mechanism is prepared by combination of these two mechanisms for n-heptane and iso-octane blended fuel, which includes 101 species and 594 reactions. New mechanism optimization is performed using genetic algorithm and multi-zone model. Mechanism contains low temperature heat release region, which decreases with increasing octane number. The results showed that the optimized chemical kinetic mechanism is capable of predicting engine-related combustion and performance parameters. Also after implementing the optimized mechanism, engine unburned HC and CO emissions predicted by the model are in good agreement with the corresponding experimental data

Combustion control for diesel engines with direct injection

Energy Technology Data Exchange (ETDEWEB)

Jeschke, J.; Henn, M.; Lang, T.; Wendt, J.; Nitzke, H.G.; Mannigel, D. [Volkswagen AG (Germany)

2007-07-01

This article looks at a new cylinder pressure-based combustion control for DI diesel engines that has been developed by Volkswagen. This cylinder pressure-based control uses cylinder pressure sensors that are integrated in the glow plugs. The description and the evaluation of these sensors form a main part of this article as they are a central element in the new diesel management system. The test and development phase in connection with a rapid prototyping system and the realisation of the combustion control algorithms in a diesel control unit are also described. Finally, results from use of the closed-loop combustion control with different applications on a diesel engine are presented. (orig.)

Staged fluidized-bed combustion and filter system

International Nuclear Information System (INIS)

Mei, J.S.; Halow, J.S.

1994-01-01

A staged fluidized-bed combustion and filter system are described for substantially reducing the quantity of waste through the complete combustion into ash-type solids and gaseous products. The device has two fluidized-bed portions, the first primarily as a combustor/pyrolyzer bed, and the second as a combustor/filter bed. The two portions each have internal baffles to define stages so that material moving therein as fluidized beds travel in an extended route through those stages. Fluidization and movement is achieved by the introduction of gases into each stage through a directional nozzle. Gases produced in the combustor/pyrolyzer bed are permitted to travel into corresponding stages of the combustor/filter bed through screen filters that permit gas flow but inhibit solids flow. Any catalyst used in the combustor/filter bed is recycled. The two beds share a common wall to minimize total volume of the system. A slightly modified embodiment can be used for hot gas desulfurization and sorbent regeneration. Either side-by-side rectangular beds or concentric beds can be used. The system is particularly suited to the processing of radioactive and chemically hazardous waste. 10 figures

Impact of mixing chemically heterogeneous groundwaters on the sustainability of an open-loop groundwater heat pump

Science.gov (United States)

Burté, L.; Farasin, J.; Cravotta, C., III; Gerard, M. F.; Cotiche Baranger, C.; Aquilina, L.; Le Borgne, T.

2017-12-01

Geothermal systems using shallow aquifers are commonly used for heating and cooling. The sustainability of these systems can be severely impacted by the occurrence of clogging process. The geothermal loop operation (including pumping of groundwater, filtering and heat extraction through exchangers and cooled water injection) can lead to an unexpected biogeochemical reactivity and scaling formation that can ultimately lead to the shutdown of the geothermal doublet. Here, we report the results of investigations carried out on a shallow geothermal doublet (dynamic). Hydrochemical data collected at the pumping well showed that groundwater was chemically heterogeneous long the 11 meters well screen. While the aquifer was dominantly oxic, a localized inflow of anoxic water was detected and evaluated to produce about 40% of the total flow . The mixture of chemically heterogeneous water induced by pumping lead to the oxidation of reductive species and thus to the formation of biogenic precipitates responsible for clogging. The impact of pumping waters of different redox potential and chemical characteristics was quantified by numerical modeling using PHREEQC. These results shows that natural chemical heterogeneity can occur at a small scale in heterogeneous aquifers and highlight the importance of their characterization during the production well testing and the geothermal loop operation in order to take preventive measures to avoid clogging.

Radiative heat transfer in turbulent combustion systems theory and applications

CERN Document Server

Modest, Michael F

2016-01-01

This introduction reviews why combustion and radiation are important, as well as the technical challenges posed by radiation. Emphasis is on interactions among turbulence, chemistry and radiation (turbulence-chemistry-radiation interactions – TCRI) in Reynolds-averaged and large-eddy simulations. Subsequent chapters cover: chemically reacting turbulent flows; radiation properties, Reynolds transport equation (RTE) solution methods, and TCRI; radiation effects in laminar flames; TCRI in turbulent flames; and high-pressure combustion systems. This Brief presents integrated approach that includes radiation at the outset, rather than as an afterthought. It stands as the most recent developments in physical modeling, numerical algorithms, and applications collected in one monograph.

Combustor nozzle for a fuel-flexible combustion system

Science.gov (United States)

Haynes, Joel Meier [Niskayuna, NY; Mosbacher, David Matthew [Cohoes, NY; Janssen, Jonathan Sebastian [Troy, NY; Iyer, Venkatraman Ananthakrishnan [Mason, OH

2011-03-22

A combustor nozzle is provided. The combustor nozzle includes a first fuel system configured to introduce a syngas fuel into a combustion chamber to enable lean premixed combustion within the combustion chamber and a second fuel system configured to introduce the syngas fuel, or a hydrocarbon fuel, or diluents, or combinations thereof into the combustion chamber to enable diffusion combustion within the combustion chamber.

Development of Aerosol Scrubbing Test Loop for Containment Filtered Venting System

International Nuclear Information System (INIS)

Lee, Doo Yong; Jung, Woo Young; Lee, Hyun Chul; Lee, Jong Chan; Kim, Gyu Tae

2016-01-01

The scrubber tank is filled with scrubbing water with the chemical additives. The droplet separator based on a cyclone is installed above the scrubbing water pool to remove the large droplets that may clog a metal fiber filter installed at the upper section of the scrubber tank. The outlet piping is connected from the scrubber tank to the molecular sieve to chemically remove the gaseous iodine. The aerosol as a particle is physically captured in the scrubbing water pool passing through the scrubbing nozzle as well as the metal fiber filter. The gaseous iodine such as molecular iodine as well as organic iodide is chemically removed in the scrubbing water pool and molecular sieve. The thermal-hydraulic as well as scrubbing performance for the CFVS should be verified with the experiments. The experiment can be divided into the filtration component based experiment and whole system based one. In this paper, the aerosol scrubbing test loop developed to test the thermal-hydraulic and aerosol scrubbing performance of the scrubbing nozzle with the scrubbing water pool is introduced. The aerosol scrubbing test loop has been developed as a part of the Korean CFVS project. In this loop, the filtration components such as the scrubbing nozzle submerged in the scrubbing water pool as well as the cyclone as droplet separator can be tested under the CFVS operating conditions. The aerosol scrubbing performance of the filtration components including pool scrubbing behavior can be tested with the aerosol generation and feeding system and aerosol measurement system.

Development of Aerosol Scrubbing Test Loop for Containment Filtered Venting System

Energy Technology Data Exchange (ETDEWEB)

Lee, Doo Yong; Jung, Woo Young; Lee, Hyun Chul; Lee, Jong Chan; Kim, Gyu Tae [FNC Technology, Yongin (Korea, Republic of)

2016-05-15

The scrubber tank is filled with scrubbing water with the chemical additives. The droplet separator based on a cyclone is installed above the scrubbing water pool to remove the large droplets that may clog a metal fiber filter installed at the upper section of the scrubber tank. The outlet piping is connected from the scrubber tank to the molecular sieve to chemically remove the gaseous iodine. The aerosol as a particle is physically captured in the scrubbing water pool passing through the scrubbing nozzle as well as the metal fiber filter. The gaseous iodine such as molecular iodine as well as organic iodide is chemically removed in the scrubbing water pool and molecular sieve. The thermal-hydraulic as well as scrubbing performance for the CFVS should be verified with the experiments. The experiment can be divided into the filtration component based experiment and whole system based one. In this paper, the aerosol scrubbing test loop developed to test the thermal-hydraulic and aerosol scrubbing performance of the scrubbing nozzle with the scrubbing water pool is introduced. The aerosol scrubbing test loop has been developed as a part of the Korean CFVS project. In this loop, the filtration components such as the scrubbing nozzle submerged in the scrubbing water pool as well as the cyclone as droplet separator can be tested under the CFVS operating conditions. The aerosol scrubbing performance of the filtration components including pool scrubbing behavior can be tested with the aerosol generation and feeding system and aerosol measurement system.

Hardware-in-the-loop simulation for the virtual application of control functions for a coordination of the interaction between a gasoline engine and the 14V-power electrical system; Hardware-in-the-Loop-Simulation fuer die virtuelle Applikation von Steuerungsfunktionen zur Motor-Energiebordnetz-Koordination

Energy Technology Data Exchange (ETDEWEB)

Schiele, Thomas

2010-07-01

The development of advanced engine management systems increasingly is supported by model-based development tools. Thereby the hardware-in-the-loop simulation is one of these tools. The author of the contribution under consideration reports on an extension of the capabilities of the hardware-in-the-loop simulation from the classic functional testing and safety tests up to the model-based application. Using the control functions for the coordination of the interaction between a gasoline engine and the 14V-power electrical system as an example, the practical application of hardware-in-the-loop systems is presented. Here, the author reviews on the state of technology for the real-time modeling of internal combustion engines and wiring systems.

From orbital debris capture systems through internal combustion engines on Mars

Science.gov (United States)

1991-01-01

The investigation and conceptualization of an orbital debris collector was the primary area of design. In addition, an alternate structural design for Space Station Freedom and systems supporting resource utilization at Mars and the moon were studied. Hardware for production of oxygen from simulate Mars atmosphere was modified to permit more reliable operation at low pressures (down to 10 mb). An internal combustion engine was altered to study how Mars atmosphere could be used as a diluent to control combustion temperatures and avoid excess Mars propellant production requirements that would result from either methane-rich or oxygen-rich, methane-oxygen combustion. An elastic loop traction system that could be used for lunar construction vehicles was refined to permit testing. A parabolic heat rejection radiator system was designed and built to determine whether it was capable of increasing heat rejection rates during lunar daytime operation. In addition, an alternate space station truss design, utilizing a pre-integrated concept, was studied and found to reduce estimate extravehicular activity (EVA) time and increase the structural integrity when compared to the original Warren truss concept. An orbital-debris-capturing spacecraft design which could be mated with the Orbital Maneuvering Vehicle was studied. The design identified Soviet C-1B boosters as the best targets of opportunity in Earth orbits between an altitude of 900 km and 1100 km and at an inclination of 82.9 deg. A dual robot pallet, which could be spun to match the tumbling rate of the C-1B booster, was developed as the conceptual design.

14 CFR 25.833 - Combustion heating systems.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Combustion heating systems. 25.833 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Design and Construction Ventilation and Heating § 25.833 Combustion heating systems. Combustion heaters must be approved. [Amdt. 25-72, 55 FR 29783, July 20, 1990...

Prediction of Combustion Instability with Detailed Chemical Kinetics

Science.gov (United States)

2014-12-01

of combustion instability. The mechanisms used for methane oxidation are the GRI 1.2 set that comprises of 32 chemical species and 177 reactions. All...with a single step global reaction and the GRI -1.2 kinetics mechanism which contains 177 reactions. The paper is organized as follows, Section II...flame speeds10. GRI -1.2 is a more complete set of hydrocarbon reactions consisting of 177 reactions involving 32 species and was optimized for natural

Chemical Distances for Percolation of Planar Gaussian Free Fields and Critical Random Walk Loop Soups

Science.gov (United States)

Ding, Jian; Li, Li

2018-06-01

We initiate the study on chemical distances of percolation clusters for level sets of two-dimensional discrete Gaussian free fields as well as loop clusters generated by two-dimensional random walk loop soups. One of our results states that the chemical distance between two macroscopic annuli away from the boundary for the random walk loop soup at the critical intensity is of dimension 1 with positive probability. Our proof method is based on an interesting combination of a theorem of Makarov, isomorphism theory, and an entropic repulsion estimate for Gaussian free fields in the presence of a hard wall.

The Evaluation of Solid Wastes Reduction with Combustion System in the Combustion Chamber

International Nuclear Information System (INIS)

Prayitno; Sukosrono

2007-01-01

The evaluation of solid wastes reduction with combustion system is used for weight reduction factor. The evaluation was done design system of combustion chamber furnace and the experiment was done by burning a certain weight of paper, cloth, plastic and rubber in the combustion chamber. The evaluation of paper wastes, the ratio of wastes (paper, cloth, plastic and rubber) against the factor of weight reduction (%) were investigated. The condition was dimension of combustion chamber furnace = 0.6 X 0.9 X 1.20 X 1 m with combustion chamber and gas chamber and reached at the wastes = 2.500 gram, oxygen pressure 0.5 Bar, wastes ratio : paper : cloth : plastic : rubber = 55 : 10 : 30 : 5, the reduction factor = 6.36 %. (author)

Risk analysis of highly combustible gas storage, supply, and distribution systems in PWR plants

International Nuclear Information System (INIS)

Simion, G.P.; VanHorn, R.L.; Smith, C.L.; Bickel, J.H.; Sattison, M.B.; Bulmahn, K.D.

1993-06-01

This report presents the evaluation of the potential safety concerns for pressurized water reactors (PWRs) identified in Generic Safety Issue 106, Piping and the Use of Highly Combustible Gases in Vital Areas. A Westinghouse four-loop PWR plant was analyzed for the risk due to the use of combustible gases (predominantly hydrogen) within the plant. The analysis evaluated an actual hydrogen distribution configuration and conducted several sensitivity studies to determine the potential variability among PWRs. The sensitivity studies were based on hydrogen and safety-related equipment configurations observed at other PWRs within the United States. Several options for improving the hydrogen distribution system design were identified and evaluated for their effect on risk and core damage frequency. A cost/benefit analysis was performed to determine whether alternatives considered were justifiable based on the safety improvement and economics of each possible improvement

Slow Invariant Manifolds in Chemically Reactive Systems

Science.gov (United States)

Paolucci, Samuel; Powers, Joseph M.

2006-11-01

The scientific design of practical gas phase combustion devices has come to rely on the use of mathematical models which include detailed chemical kinetics. Such models intrinsically admit a wide range of scales which renders their accurate numerical approximation difficult. Over the past decade, rational strategies, such as Intrinsic Low Dimensional Manifolds (ILDM) or Computational Singular Perturbations (CSP), for equilibrating fast time scale events have been successfully developed, though their computation can be challenging and their accuracy in most cases uncertain. Both are approximations to the preferable slow invariant manifold which best describes how the system evolves in the long time limit. Strategies for computing the slow invariant manifold are examined, and results are presented for practical combustion systems.

Transformations of inorganic coal constituents in combustion systems

Energy Technology Data Exchange (ETDEWEB)

Helble, J.J. (ed.); Srinivasachar, S.; Wilemski, G.; Boni, A.A. (PSI Technology Co., Andover, MA (United States)); Kang, Shin-Gyoo; Sarofim, A.F.; Graham, K.A.; Beer, J.M. (Massachusetts Inst. of Tech., Cambridge, MA (United States)); Peterson, T.W.; Wendt, J.O.L.; Gallagher, N.B.; Bool, L. (Arizona Univ., Tucson, AZ (United States)); Huggins, F.E.; Huffman, G.P.; Shah, N.; Shah, A. (Kentucky Univ., Lexingt

1992-11-01

The inorganic constituents or ash contained in pulverized coal significantly increase the environmental and economic costs of coal utilization. For example, ash particles produced during combustion may deposit on heat transfer surfaces, decreasing heat transfer rates and increasing maintenance costs. The minimization of particulate emissions often requires the installation of cleanup devices such as electrostatic precipitators, also adding to the expense of coal utilization. Despite these costly problems, a comprehensive assessment of the ash formation and had never been attempted. At the start of this program, it was hypothesized that ash deposition and ash particle emissions both depended upon the size and chemical composition of individual ash particles. Questions such as: What determines the size of individual ash particles What determines their composition Whether or not particles deposit How combustion conditions, including reactor size, affect these processes remained to be answered. In this 6-year multidisciplinary study, these issues were addressed in detail. The ambitious overall goal was the development of a comprehensive model to predict the size and chemical composition distributions of ash produced during pulverized coal combustion. Results are described.

Ash chemistry and behavior in advanced co-combustion

Energy Technology Data Exchange (ETDEWEB)

Hupa, M; Skrifvars, B J [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

1997-10-01

The purpose of this LIEKKI 2 project is to report results achieved within the EU/JOULE/OPTEB project to the Finnish combustion research community through the LIEKKI program. The purpose of the EU/JOULE/OPTEB project is to find prediction methods for evaluating ash behavior, such as slagging, fouling and corrosion propensity, in full scale combustion systems through chemical or mineralogical analyses, intelligent laboratory tests and chemistry calculations. The project focuses on coals, coal mixtures and coal biomass mixtures fired in advanced combustion systems, such as fluidized bed boilers, pulverized fuel boilers with critical steam values etc. The project will make use of (1) advanced multi-component combustion equilibrium calculations, (2) ash sintering tendency laboratory tests and (3) chemical evaluations of slagging, fouling and corrosion measurements in full scale units. (orig.)

Advanced exergoenvironmental analysis of a near-zero emission power plant with chemical looping combustion.

Science.gov (United States)

Petrakopoulou, Fontina; Tsatsaronis, George; Morosuk, Tatiana

2012-03-06

Carbon capture and storage (CCS) from power plants can be used to mitigate CO(2) emissions from the combustion of fossil fuels. However, CCS technologies are energy intensive, decreasing the operating efficiency of a plant and increasing its costs. Recently developed advanced exergy-based analyses can uncover the potential for improvement of complex energy conversion systems, as well as qualify and quantify plant component interactions. In this paper, an advanced exergoenvironmental analysis is used for the first time as means to evaluate an oxy-fuel power plant with CO(2) capture. The environmental impacts of each component are split into avoidable/unavoidable and endogenous/exogenous parts. In an effort to minimize the environmental impact of the plant operation, we focus on the avoidable part of the impact (which is also split into endogenous and exogenous parts) and we seek ways to decrease it. The results of the advanced exergoenvironmental analysis show that the majority of the environmental impact related to the exergy destruction of individual components is unavoidable and endogenous. Thus, the improvement potential is rather limited, and the interactions of the components are of lower importance. The environmental impact of construction of the components is found to be significantly lower than that associated with their operation; therefore, our suggestions for improvement focus on measures concerning the reduction of exergy destruction and pollutant formation.

Development of a NO/x/-free combustion system

Science.gov (United States)

Sadakata, M.; Furusawa, T.; Kunii, D.; Imagawa, M.; Nawada, M.

1980-04-01

The development of a NO(x)-free combustion-heating system realizing both pollution control and energy savings is described. An experiment was carried out by using a small model plant. The system consists of a combustion furnace and a new-type multifunctional heat exchanger. The heat exchanger is a rotary continuous type designed for soot collection and for catalytic combustion of CO and H2 as well as for preheating combustion air.

Jet plume injection and combustion system for internal combustion engines

Science.gov (United States)

Oppenheim, Antoni K.; Maxson, James A.; Hensinger, David M.

1993-01-01

An improved combustion system for an internal combustion engine is disclosed wherein a rich air/fuel mixture is furnished at high pressure to one or more jet plume generator cavities adjacent to a cylinder and then injected through one or more orifices from the cavities into the head space of the cylinder to form one or more turbulent jet plumes in the head space of the cylinder prior to ignition of the rich air/fuel mixture in the cavity of the jet plume generator. The portion of the rich air/fuel mixture remaining in the cavity of the generator is then ignited to provide a secondary jet, comprising incomplete combustion products which are injected into the cylinder to initiate combustion in the already formed turbulent jet plume. Formation of the turbulent jet plume in the head space of the cylinder prior to ignition has been found to yield a higher maximum combustion pressure in the cylinder, as well as shortening the time period to attain such a maximum pressure.

Combustion science and engineering

CERN Document Server

Annamalai, Kalyan

2006-01-01

Introduction and Review of Thermodynamics Introduction Combustion Terminology Matter and Its Properties Microscopic Overview of Thermodynamics Conservation of Mass and Energy and the First Law of Thermodynamics The Second Law of Thermodynamics Summary Stoichiometry and Thermochemistry of Reacting Systems Introduction Overall Reactions Gas Analyses Global Conservation Equations for Reacting Systems Thermochemistry Summary Appendix Reaction Direction and Equilibrium Introduction Reaction Direction and Chemical Equilibrium Chemical Equilibrium Relations Vant Hoff Equation Adi

Fifteenth combustion research conference

International Nuclear Information System (INIS)

1993-01-01

The BES research efforts cover chemical reaction theory, experimental dynamics and spectroscopy, thermodynamics of combustion intermediates, chemical kinetics, reaction mechanisms, combustion diagnostics, and fluid dynamics and chemically reacting flows. 98 papers and abstracts are included. Separate abstracts were prepared for the papers

Coupling of high temperature nuclear reactor with chemical plant by means of steam loop with heat pump

Directory of Open Access Journals (Sweden)

Kopeć Mariusz

2017-01-01

Full Text Available High temperature nuclear reactors (HTR can be used as an excellent, emission-free source of technological heat for various industrial applications. Their outlet helium temperature (700°-900°C allows not only for heat supply to all processes below 600°C (referred to as “steam class”, but also enables development of clean nuclear-assisted hydrogen production or coal liquefaction technologies with required temperatures up to 900°C (referred to as “chemical class”. This paper presents the results of analyses done for various configurations of the steam transport loop coupled with the high-temperature heat pump designed for “chemical class” applications. The advantages and disadvantages as well as the key issues are discussed in comparison with alternative solutions, trying to answer the question whether the system with the steam loop and the hightemperature heat pump is viable and economically justified.

Hydraulic loop: practices using open control systems

International Nuclear Information System (INIS)

Carrasco, J.A.; Alonso, L.; Sanchez, F.

1998-01-01

The Tecnatom Hydraulic Loop is a dynamic training platform. It has been designed with the purpose of improving the work in teams. With this system, the student can obtain a full scope vision of a system. The hydraulic Loop is a part of the Tecnatom Maintenance Centre. The first objective of the hydraulic Loop is the instruction in components, process and process control using open control system. All the personal of an electric power plant can be trained in the Hydraulic Loop with specific courses. The development of a dynamic tool for tests previous to plant installations has been an additional objective of the Hydraulic Loop. The use of this platform is complementary to the use of full-scope simulators in order to debug and to analyse advanced control strategies. (Author)

CSP-based chemical kinetics mechanisms simplification strategy for non-premixed combustion: An application to hybrid rocket propulsion

KAUST Repository

Ciottoli, Pietro P.

2017-08-14

A set of simplified chemical kinetics mechanisms for hybrid rocket applications using gaseous oxygen (GOX) and hydroxyl-terminated polybutadiene (HTPB) is proposed. The starting point is a 561-species, 2538-reactions, detailed chemical kinetics mechanism for hydrocarbon combustion. This mechanism is used for predictions of the oxidation of butadiene, the primary HTPB pyrolysis product. A Computational Singular Perturbation (CSP) based simplification strategy for non-premixed combustion is proposed. The simplification algorithm is fed with the steady-solutions of classical flamelet equations, these being representative of the non-premixed nature of the combustion processes characterizing a hybrid rocket combustion chamber. The adopted flamelet steady-state solutions are obtained employing pure butadiene and gaseous oxygen as fuel and oxidizer boundary conditions, respectively, for a range of imposed values of strain rate and background pressure. Three simplified chemical mechanisms, each comprising less than 20 species, are obtained for three different pressure values, 3, 17, and 36 bar, selected in accordance with an experimental test campaign of lab-scale hybrid rocket static firings. Finally, a comprehensive strategy is shown to provide simplified mechanisms capable of reproducing the main flame features in the whole pressure range considered.

Model experiments on simulation of the WWER water-chemical conditions at loop facilities of the MIR reactor

International Nuclear Information System (INIS)

Benderskaya, O.S.; Zotov, E.A.; Kuprienko, V.A.; Ovchinnikov, V.A.

1999-01-01

The experiments on simulation of the WWER type reactors water-chemical conditions have been started at the State Scientific Center RIAR. These experiments are being conducted at the multi-loop research MIR reactor at the PVK-2 loop facility. The dosage stand was created. It allows introduction of boric acid, potassium and lithium hydroxides, ammonia solutions and gaseous hydrogen. Corrosion tests of the Russian E-635 and E-110 alloys are being conducted at the PVK-2 loop under the WWER water-chemical conditions. If necessary, fuel elements are periodically extracted from the reactor to perform visual examination, to measure their length, diameter, to remove the deposits from the claddings, to measure the burnup and to distribute the fission products over the fuel element by gamma-spectrometry. The chemical analytical 'on line' equipment produced by the ORBISPHERE Laboratory (Switzerland) will be commissioned in the nearest future to measure concentration of the dissolved hydrogen and oxygen as well as pH and specific conductivity. The objective of the report is to familiarize the participants of the IAEA Technical Committee with the capabilities of performing the model water-chemical experiments under the MIR reactor loop facility conditions. (author)

Advanced radiant combustion system. Final report, September 1989--September 1996

Energy Technology Data Exchange (ETDEWEB)

Sullivan, J.D.; Carswell, M.G.; Long, F.S.

1996-09-01

Results of the Advanced Radiant Combustion System (ARCS) project are presented in this report. This work was performed by Alzeta Corporation as prime contractor under a contract to the U.S. Department of Energy Office of Industrial Technologies as part of a larger DOE program entitled Research Program for Advanced Combustion Systems. The goals of the Alzeta ARCS project were to (a) Improve the high temperature performance characteristics of porous surface ceramic fiber burners, (b) Develop an Advanced Radiant Combustion System (ARCS) that combines combustion controls with an advanced radiant burner, and (c) Demonstrate the advanced burner and controls in an industrial application. Prior to the start of this project, Alzeta had developed and commercialized a porous surface radiant burner, the Pyrocore{trademark} burner. The product had been commercially available for approximately 5 years and had achieved commercial success in a number of applications ranging from small burners for commercial cooking equipment to large burners for low temperature industrial fluid heating applications. The burner was not recommended for use in applications with process temperatures above 1000{degrees}F, which prevented the burner from being used in intermediate to high temperature processes in the chemical and petroleum refining industries. The interest in increasing the maximum use temperature of the burner was motivated in part by a desire to expand the number of applications that could use the Pyrocore product, but also because many of the fluid sensitive heating applications of interest would benefit from the distributed flux characteristic of porous surface burners. Background information on porous surface radiant burners, and a discussion of advantages that would be provided by an improved product, are presented in Section 2.

Chemical Processes Related to Combustion in Fluidised Bed

Energy Technology Data Exchange (ETDEWEB)

Steenari, Britt-Marie; Lindqvist, Oliver [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Environmental Inorganic Chemistry

2002-12-01

with evaluation of other biomass ash particles and, as an extension, the speciation of Cu and Zn will be studied as well. Ash fractions from combustion of MSW in a BFB boiler have been investigated regarding composition and leaching properties, i.e. environmental impact risks. The release of salts from the cyclone ash fraction can be minimised by the application of a simple washing process, thus securing that the leaching of soluble substances stays within the regulative limits. The MSW ash - water systems contain some interesting chemical issues, such as the interactions between Cr(VI) and reducing substances like Al-metal. The understanding of such chemical processes is important since it gives a possibility to predict effects of a change in ash composition. An even more detailed understanding of interactions between a solution containing ions and particle surfaces can be gained by theoretical modelling. In this project (and with additional unding from Aangpannefoereningens Forskningsstiftelse) a theoretical description of ion-ion interactions and the solid-liquid-interface has been developed. Some related issues are also included in this report. The publication of a paper on the reactions of ammonia in the presence of a calcining limestone surface is one of them. A review paper on the influence of combustion conditions on the properties of fly ash and its applicability as a cement replacement in concrete is another. The licentiate thesis describing the sampling and measurement of Cd in flue gas is also included since it was finalised during the present period. A co-operation project involving the Geology Dept. at Goeteborg Univ. and our group is briefly discussed. This project concerns the utilisation of granules produced from wood ash and dolomite as nutrient source for forest soil. Finally, the plans for our flue gas simulator facility are discussed.

Incremental Closed-loop Identification of Linear Parameter Varying Systems

DEFF Research Database (Denmark)

Bendtsen, Jan Dimon; Trangbæk, Klaus

2011-01-01

, closed-loop system identification is more difficult than open-loop identification. In this paper we prove that the so-called Hansen Scheme, a technique known from linear time-invariant systems theory for transforming closed-loop system identification problems into open-loop-like problems, can be extended...

Combustion physics

Science.gov (United States)

Jones, A. R.

1985-11-01

Over 90% of our energy comes from combustion. By the year 2000 the figure will still be 80%, even allowing for nuclear and alternative energy sources. There are many familiar examples of combustion use, both domestic and industrial. These range from the Bunsen burner to large flares, from small combustion chambers, such as those in car engines, to industrial furnaces for steel manufacture or the generation of megawatts of electricity. There are also fires and explosions. The bountiful energy release from combustion, however, brings its problems, prominent among which are diminishing fuel resources and pollution. Combustion science is directed towards finding ways of improving efficiency and reducing pollution. One may ask, since combustion is a chemical reaction, why physics is involved: the answer is in three parts. First, chemicals cannot react unless they come together. In most flames the fuel and air are initially separate. The chemical reaction in the gas phase is very fast compared with the rate of mixing. Thus, once the fuel and air are mixed the reaction can be considered to occur instantaneously and fluid mechanics limits the rate of burning. Secondly, thermodynamics and heat transfer determine the thermal properties of the combustion products. Heat transfer also plays a role by preheating the reactants and is essential to extracting useful work. Fluid mechanics is relevant if work is to be performed directly, as in a turbine. Finally, physical methods, including electric probes, acoustics, optics, spectroscopy and pyrometry, are used to examine flames. The article is concerned mainly with how physics is used to improve the efficiency of combustion.

Combustion of diesel fuel from a toxicological perspective. I. Origin of incomplete combustion products.

Science.gov (United States)

Scheepers, P T; Bos, R P

1992-01-01

Since the use of diesel engines is still increasing, the contribution of their incomplete combustion products to air pollution is becoming ever more important. The presence of irritating and genotoxic substances in both the gas phase and the particulate phase constituents is considered to have significant health implications. The quantity of soot particles and the particle-associated organics emitted from the tail pipe of a diesel-powered vehicle depend primarily on the engine type and combustion conditions but also on fuel properties. The quantity of soot particles in the emissions is determined by the balance between the rate of formation and subsequent oxidation. Organics are absorbed onto carbon cores in the cylinder, in the exhaust system, in the atmosphere and even on the filter during sample collection. Diesel fuel contains polycyclic aromatic hydrocarbons (PAHs) and some alkyl derivatives. Both groups of compounds may survive the combustion process. PAHs are formed by the combustion of crankcase oil or may be resuspended from engine and/or exhaust deposits. The conversion of parent PAHs to oxygenated and nitrated PAHs in the combustion chamber or in the exhaust system is related to the vast amount of excess combustion air that is supplied to the engine and the high combustion temperature. Whether the occurrence of these derivatives is characteristic for the composition of diesel engine exhaust remains to be ascertained. After the emission of the particles, their properties may change because of atmospheric processes such as aging and resuspension. The particle-associated organics may also be subject to (photo)chemical conversions or the components may change during sampling and analysis. Measurement of emissions of incomplete combustion products as determined on a chassis dynamometer provides knowledge of the chemical composition of the particle-associated organics. This knowledge is useful as a basis for a toxicological evaluation of the health hazards of

Combustion

CERN Document Server

Glassman, Irvin

1997-01-01

This Third Edition of Glassman's classic text clearly defines the role of chemistry, physics, and fluid mechanics as applied to the complex topic of combustion. Glassman's insightful introductory text emphasizes underlying physical and chemical principles, and encompasses engine technology, fire safety, materials synthesis, detonation phenomena, hydrocarbon fuel oxidation mechanisms, and environmental considerations. Combustion has been rewritten to integrate the text, figures, and appendixes, detailing available combustion codes, making it not only an excellent introductory text but also an important reference source for professionals in the field. Key Features * Explains complex combustion phenomena with physical insight rather than extensive mathematics * Clarifies postulates in the text using extensive computational results in figures * Lists modern combustion programs indicating usage and availability * Relates combustion concepts to practical applications.

Study of physico-chemical release of uranium and plutonium oxides during the combustion of polycarbonate and of ruthenium during the combustion of solvents used in the reprocessing of nuclear fuel

International Nuclear Information System (INIS)

Bouilloux, L.

1998-01-01

The level of consequences concerning a fire in a nuclear facility is in part estimated by the quantities and the physico-chemical forms of radioactive compounds that may be emitted out of the facility. It is therefore necessary to study the contaminant release from the fire. Because of the multiplicity of the scenarios, two research subjects were retained. The first one concerns the study of the uranium or plutonium oxides chemical release during the combustion of the polycarbonate glove box sides. The second one is about the physico chemical characterisation of the ruthenium release during the combustion of an organic solvent mixture (tributyl phosphate-dodecane) used for the nuclear fuel reprocessing. Concerning the two research subjects, the chemical release, i.e. means the generation of contaminant compounds gaseous in the fire, was modelled using thermodynamical simulations. Experiments were done in order to determine the ruthenium release factor during solvent combustion. A cone calorimeter was used for small scale experiments. These results were then validated by large scale tests under conditions close to the industrial process. Thermodynamical simulations, for the two scenarios studied. Furthermore, the experiments on solvent combustion allowed the determination of a suitable ruthenium release factor. Finally, the mechanism responsible of the ruthenium release has been found. (author)

Chemical Looping Gasification for Hydrogen Enhanced Syngas Production with In-Situ CO₂ Capture

Energy Technology Data Exchange (ETDEWEB)

Kathe, Mandar [Ohio State University, Columbus, OH (United States); Xu, Dikai [Ohio State University, Columbus, OH (United States); Hsieh, Tien-Lin [Ohio State University, Columbus, OH (United States); Simpson, James [Ohio State University, Columbus, OH (United States); Statnick, Robert [Ohio State University, Columbus, OH (United States); Tong, Andrew [Ohio State University, Columbus, OH (United States); Fan, Liang-Shih [Ohio State University, Columbus, OH (United States)

2014-12-31

This document is the final report for the project titled “Chemical Looping Gasification for Hydrogen Enhanced Syngas Production with In-Situ CO₂ Capture” under award number FE0012136 for the performance period 10/01/2013 to 12/31/2014.This project investigates the novel Ohio State chemical looping gasification technology for high efficiency, cost efficiency coal gasification for IGCC and methanol production application. The project developed an optimized oxygen carrier composition, demonstrated the feasibility of the concept and completed cold-flow model studies. WorleyParsons completed a techno-economic analysis which showed that for a coal only feed with carbon capture, the OSU CLG technology reduced the methanol required selling price by 21%, lowered the capital costs by 28%, increased coal consumption efficiency by 14%. Further, using the Ohio State Chemical Looping Gasification technology resulted in a methanol required selling price which was lower than the reference non-capture case.

A theory of desynchronisable closed loop system

Directory of Open Access Journals (Sweden)

Harsh Beohar

2010-10-01

Full Text Available The task of implementing a supervisory controller is non-trivial, even though different theories exist that allow automatic synthesis of these controllers in the form of automata. One of the reasons for this discord is due to the asynchronous interaction between a plant and its controller in implementations, whereas the existing supervisory control theories assume synchronous interaction. As a consequence the implementation suffer from the so-called inexact synchronisation problem. In this paper we address the issue of inexact synchronisation in a process algebraic setting, by solving a more general problem of refinement. We construct an asynchronous closed loop system by introducing a communication medium in a given synchronous closed loop system. Our goal is to find sufficient conditions under which a synchronous closed loop system is branching bisimilar to its corresponding asynchronous closed loop system.

Evaluation of system codes for analyzing naturally circulating gas loop

International Nuclear Information System (INIS)

Lee, Jeong Ik; No, Hee Cheon; Hejzlar, Pavel

2009-01-01

Steady-state natural circulation data obtained in a 7 m-tall experimental loop with carbon dioxide and nitrogen are presented in this paper. The loop was originally designed to encompass operating range of a prototype gas-cooled fast reactor passive decay heat removal system, but the results and conclusions are applicable to any natural circulation loop operating in regimes having buoyancy and acceleration parameters within the ranges validated in this loop. Natural circulation steady-state data are compared to numerical predictions by two system analysis codes: GAMMA and RELAP5-3D. GAMMA is a computational tool for predicting various transients which can potentially occur in a gas-cooled reactor. The code has a capability of analyzing multi-dimensional multi-component mixtures and includes models for friction, heat transfer, chemical reaction, and multi-component molecular diffusion. Natural circulation data with two gases show that the loop operates in the deteriorated turbulent heat transfer (DTHT) regime which exhibits substantially reduced heat transfer coefficients compared to the forced turbulent flow. The GAMMA code with an original heat transfer package predicted conservative results in terms of peak wall temperature. However, the estimated peak location did not successfully match the data. Even though GAMMA's original heat transfer package included mixed-convection regime, which is a part of the DTHT regime, the results showed that the original heat transfer package could not reproduce the data with sufficient accuracy. After implementing a recently developed correlation and corresponding heat transfer regime map into GAMMA to cover the whole range of the DTHT regime, we obtained better agreement with the data. RELAP5-3D results are discussed in parallel.

Droplet evaporation and combustion in a liquid-gas multiphase system

Science.gov (United States)

Muradoglu, Metin; Irfan, Muhammad

2017-11-01

Droplet evaporation and combustion in a liquid-gas multiphase system are studied computationally using a front-tracking method. One field formulation is used to solve the flow, energy and species equations with suitable jump conditions. Both phases are assumed to be incompressible; however, the divergence-free velocity field condition is modified to account for the phase change at the interface. Both temperature and species gradient driven phase change processes are simulated. Extensive validation studies are performed using the benchmark cases: The Stefan and the sucking interface problems, d2 law and wet bulb temperature comparison with the psychrometric chart values. The phase change solver is then extended to incorporate the burning process following the evaporation as a first step towards the development of a computational framework for spray combustion. We used detailed chemistry, variable transport properties and ideal gas behaviour for a n-heptane droplet combustion; the chemical kinetics being handled by the CHEMKIN. An operator-splitting approach is used to advance temperature and species mass fraction in time. The numerical results of the droplet burning rate, flame temperature and flame standoff ratio show good agreement with the experimental and previous numeric.

LES SOFTWARE FOR THE DESIGN OF LOW EMISSION COMBUSTION SYSTEMS FOR VISION 21 PLANTS

International Nuclear Information System (INIS)

Steve Cannon; Baifang Zuo; Virgil Adumitroaie; Keith McDaniel; Cliff Smith

2002-01-01

Further development of a combustion Large Eddy Simulation (LES) code for the design of advanced gaseous combustion systems is described in this fifth quarterly report. CFD Research Corporation (CFDRC) is developing the LES module within the parallel, unstructured solver included in the commercial CFD-ACE+ software. In this quarter, in-situ adaptive tabulation (ISAT) for efficient chemical rate storage and retrieval was further tested in the LES code. The use of multiple trees and periodic tree dumping was investigated. Implementation of the Linear Eddy Model (LEM) for subgrid chemistry was finished for serial applications. Validation of the model on a backstep reacting case was performed. Initial calculations of the SimVal experiment were performed for various barrel lengths, equivalence ratio, combustor shapes, and turbulence models. The effects of these variables on combustion instability was studied. Georgia Tech continues the effort to parameterize the LEM over composition space so that a neural net can be used efficiently in the combustion LES code. Next quarter, the 2nd consortium meeting will be held at CFDRC. LES software development and testing will continue. Alpha testing of the code will be performed on cases of interest to the industrial consortium. Optimization of subgrid models will be pursued, particularly with the ISAT approach. Also next quarter, the demonstration of the neural net approach, for chemical kinetics speed-up in CFD-ACE+, should be accomplished

Fuel-Flexible Combustion System for Co-production Plant Applications

Energy Technology Data Exchange (ETDEWEB)

Joel Haynes; Justin Brumberg; Venkatraman Iyer; Jonathan Janssen; Ben Lacy; Matt Mosbacher; Craig Russell; Ertan Yilmaz; Williams York; Willy Ziminsky; Tim Lieuwen; Suresh Menon; Jerry Seitzman; Ashok Anand; Patrick May

2008-12-31

Future high-efficiency, low-emission generation plants that produce electric power, transportation fuels, and/or chemicals from fossil fuel feed stocks require a new class of fuel-flexible combustors. In this program, a validated combustor approach was developed which enables single-digit NO{sub x} operation for a future generation plants with low-Btu off gas and allows the flexibility of process-independent backup with natural gas. This combustion technology overcomes the limitations of current syngas gas turbine combustion systems, which are designed on a site-by-site basis, and enable improved future co-generation plant designs. In this capacity, the fuel-flexible combustor enhances the efficiency and productivity of future co-production plants. In task 2, a summary of market requested fuel gas compositions was created and the syngas fuel space was characterized. Additionally, a technology matrix and chemical kinetic models were used to evaluate various combustion technologies and to select two combustor concepts. In task 4 systems analysis of a co-production plant in conjunction with chemical kinetic analysis was performed to determine the desired combustor operating conditions for the burner concepts. Task 5 discusses the experimental evaluation of three syngas capable combustor designs. The hybrid combustor, Prototype-1 utilized a diffusion flame approach for syngas fuels with a lean premixed swirl concept for natural gas fuels for both syngas and natural gas fuels at FA+e gas turbine conditions. The hybrid nozzle was sized to accommodate syngas fuels ranging from {approx}100 to 280 btu/scf and with a diffusion tip geometry optimized for Early Entry Co-generation Plant (EECP) fuel compositions. The swozzle concept utilized existing GE DLN design methodologies to eliminate flow separation and enhance fuel-air mixing. With changing business priorities, a fully premixed natural gas & syngas nozzle, Protoytpe-1N, was also developed later in the program. It did

Chemical Kinetic Study of Nitrogen Oxides Formation Trends in Biodiesel Combustion

Directory of Open Access Journals (Sweden)

Junfeng Yang

2012-01-01

Full Text Available The use of biodiesel in conventional diesel engines results in increased NOx emissions; this presents a barrier to the widespread use of biodiesel. The origins of this phenomenon were investigated using the chemical kinetics simulation tool: CHEMKIN-2 and the CFD KIVA3V code, which was modified to account for the physical properties of biodiesel and to incorporate semidetailed mechanisms for its combustion and the formation of emissions. Parametric ϕ-T maps and 3D engine simulations were used to assess the impact of using oxygen-containing fuels on the rate of NO formation. It was found that using oxygen-containing fuels allows more O2 molecules to present in the engine cylinder during the combustion of biodiesel, and this may be the cause of the observed increase in NO emissions.

Combustion

CERN Document Server

Glassman, Irvin

2008-01-01

Combustion Engineering, a topic generally taught at the upper undergraduate and graduate level in most mechanical engineering programs, and many chemical engineering programs, is the study of rapid energy and mass transfer usually through the common physical phenomena of flame oxidation. It covers the physics and chemistry of this process and the engineering applications-from the generation of power such as the internal combustion automobile engine to the gas turbine engine. Renewed concerns about energy efficiency and fuel costs, along with continued concerns over toxic and particulate emissions have kept the interest in this vital area of engineering high and brought about new developments in both fundamental knowledge of flame and combustion physics as well as new technologies for flame and fuel control. *New chapter on new combustion concepts and technologies, including discussion on nanotechnology as related to combustion, as well as microgravity combustion, microcombustion, and catalytic combustion-all ...

Closed-loop Identification for Control of Linear Parameter Varying Systems

DEFF Research Database (Denmark)

Bendtsen, Jan Dimon; Trangbæk, Klaus

2014-01-01

, closed- loop system identification is more difficult than open-loop identification. In this paper we prove that the so-called Hansen Scheme, a technique known from linear time-invariant systems theory for transforming closed-loop system identification problems into open-loop-like problems, can...

The chemical transformation of calcium in Shenhua coal during combustion in a muffle furnace

Energy Technology Data Exchange (ETDEWEB)

Tian, Sida [North China Electric Power Univ., Beijing (China). School of Energy, Power and Mechanical Engineering; Ministry of Education, Beijing (China). Key Lab. of Condition Monitoring and Control for Power Plant Equipment; Zhuo, Yuqun; Chen, Changhe [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Ministry of Education, Beijing (China). Key Lab. for Thermal Science and Power Engineering; Shu, Xinqian [China Univ. of Mining and Technology, Beijing (China). School of Chemical and Environmental Engineering

2013-07-01

The chemical reaction characteristics of calcium in three samples of Shenhua coal, i.e. raw sample, hydrochloric acid washed sample and hydrochloric acid washed light fraction, during combustion in a muffle furnace have been investigated in this paper. Ca is bound by calcite and organic matter in Shenhua coal. X ray diffraction (XRD) phase analysis has been conducted to these samples' combustion products obtained by heating at different temperatures. It has been found that the organically-bound calcium could easily react with clays and transform into gehlenite and anorthite partially if combusted under 815 C, whilst the excluded minerals promoted the conversion of gehlenite to anorthite. Calcite in Shenhua coal decomposed into calcium oxide and partially transformed into calcium sulfate under 815 C, and formed gehlenite and anorthite under 1,050 C. Calcite and other HCl-dissolved minerals in Shenhua coal were responsible mainly for the characteristic that the clay minerals in Shenhua coal hardly became mullite during combustion.

Numerical Modeling of an Integrated Vehicle Fluids System Loop for Pressurizing a Cryogenic Tank

Science.gov (United States)

LeClair, A. C.; Hedayat, A.; Majumdar, A. K.

2017-01-01

This paper presents a numerical model of the pressurization loop of the Integrated Vehicle Fluids (IVF) system using the Generalized Fluid System Simulation Program (GFSSP). The IVF propulsion system, being developed by United Launch Alliance to reduce system weight and enhance reliability, uses boiloff propellants to drive thrusters for the reaction control system as well as to run internal combustion engines to develop power and drive compressors to pressurize propellant tanks. NASA Marshall Space Flight Center (MSFC) conducted tests to verify the functioning of the IVF system using a flight-like tank. GFSSP, a finite volume based flow network analysis software developed at MSFC, has been used to support the test program. This paper presents the simulation of three different test series, comparison of numerical prediction and test data and a novel method of presenting data in a dimensionless form. The paper also presents a methodology of implementing a compressor map in a system level code.

System and method for engine combustion

Science.gov (United States)

Sczomak, David P.; Gallon, Robert J.; Solomon, Arun S.

2018-03-13

A combustion system for use with one or more cylinder bores of an internal combustion engine includes at least one cylinder head defining first and second intake ports in fluid communication with the one or more cylinder bores. A flap is adjustably connected to the at least one cylinder head. The flap includes a first flap portion cooperating with the first intake port extending from an arm and a second flap portion cooperating with the second intake port extending from the arm and disposed adjacent the first flap portion. A controller in electrical communication with an actuator monitors the condition of the engine and actuates the flap to position the first and second flap portions between first and second positions to create a first combustion condition and a second combustion condition.

Repurposing Mass-produced Internal Combustion Engines Quantifying the Value and Use of Low-cost Internal Combustion Piston Engines for Modular Applications in Energy and Chemical Engineering Industries

Science.gov (United States)

L'Heureux, Zara E.

This thesis proposes that internal combustion piston engines can help clear the way for a transformation in the energy, chemical, and refining industries that is akin to the transition computer technology experienced with the shift from large mainframes to small personal computers and large farms of individually small, modular processing units. This thesis provides a mathematical foundation, multi-dimensional optimizations, experimental results, an engine model, and a techno-economic assessment, all working towards quantifying the value of repurposing internal combustion piston engines for new applications in modular, small-scale technologies, particularly for energy and chemical engineering systems. Many chemical engineering and power generation industries have focused on increasing individual unit sizes and centralizing production. This "bigger is better" concept makes it difficult to evolve and incorporate change. Large systems are often designed with long lifetimes, incorporate innovation slowly, and necessitate high upfront investment costs. Breaking away from this cycle is essential for promoting change, especially change happening quickly in the energy and chemical engineering industries. The ability to evolve during a system's lifetime provides a competitive advantage in a field dominated by large and often very old equipment that cannot respond to technology change. This thesis specifically highlights the value of small, mass-manufactured internal combustion piston engines retrofitted to participate in non-automotive system designs. The applications are unconventional and stem first from the observation that, when normalized by power output, internal combustion engines are one hundred times less expensive than conventional, large power plants. This cost disparity motivated a look at scaling laws to determine if scaling across both individual unit size and number of units produced would predict the two order of magnitude difference seen here. For the first

Combustible radioactive waste treatment by incineration and chemical digestion

International Nuclear Information System (INIS)

Stretz, L.A.; Crippen, M.D.; Allen, C.R.

1980-01-01

A review is given of present and planned combustible radioactive waste treatment systems in the US. Advantages and disadvantages of various systems are considered. Design waste streams are discussed in relation to waste composition, radioactive contaminants by amount and type, and special operating problems caused by the waste

Active fault diagnosis in closed-loop systems

DEFF Research Database (Denmark)

Niemann, Hans Henrik; Poulsen, Niels Kjølstad

2005-01-01

Active fault diagnosis (AFD) of parametric faults is considered in connection with closed loop feedback systems. AFD involves auxiliary signals applied on the closed loop system. A fault signature matrix is introduced in connection with AFD and it is shown that if a limited number of faults can...

Ground loops detection system in the RFX machine

International Nuclear Information System (INIS)

Bellina, F.; Pomaro, N.; Trevisan, F.

1996-01-01

RFX is a toroidal machine for the fusion research based on the RFP configuration. During the pulse, in any conductive loop close to the machine very strong currents can be induced, which may damage the diagnostics and the other instrumentation. To avoid loops, the earthing system of the machine is tree-shaped. However, an accidental contact between metallic earthed masses of the machine may give rise to an unwanted loop as well. An automatic system for the detection of ground loops in the earthing system has therefore been developed, which works continuously during shutdown intervals and between pulses. In the paper the design of the detection system is presented, together with the experimental results on prototypes. 4 refs., 3 figs., 1 tab

Tritium Management Loop Design Status

Energy Technology Data Exchange (ETDEWEB)

Rader, Jordan D. [ORNL; Felde, David K. [ORNL; McFarlane, Joanna [ORNL; Greenwood, Michael Scott [ORNL; Qualls, A L. [ORNL; Calderoni, Pattrick [Idaho National Laboratory (INL)

2017-12-01

This report summarizes physical, chemical, and engineering analyses that have been done to support the development of a test loop to study tritium migration in 2LiF-BeF2 salts. The loop will operate under turbulent flow and a schematic of the apparatus has been used to develop a model in Mathcad to suggest flow parameters that should be targeted in loop operation. The introduction of tritium into the loop has been discussed as well as various means to capture or divert the tritium from egress through a test assembly. Permeation was calculated starting with a Modelica model for a transport through a nickel window into a vacuum, and modifying it for a FLiBe system with an argon sweep gas on the downstream side of the permeation interface. Results suggest that tritium removal with a simple tubular permeation device will occur readily. Although this system is idealized, it suggests that rapid measurement capability in the loop may be necessary to study and understand tritium removal from the system.

Chemical and biological characterization of products of incomplete combustion from the simulated field burning of agricultural plastic.

Science.gov (United States)

Linak, W P; Ryan, J V; Perry, E; Williams, R W; DeMarini, D M

1989-06-01

Chemical and biological analyses were performed to characterize products of incomplete combustion emitted during the simulated open field burning of agricultural plastic. A small utility shed equipped with an air delivery system was used to simulate pile burning and forced-air-curtain incineration of a nonhalogenated agricultural plastic that reportedly consisted of polyethylene and carbon black. Emissions were analyzed for combustion gases; volatile, semi-volatile, and particulate organics; and toxic and mutagenic properties. Emission samples, as well as samples of the used (possibly pesticide-contaminated) plastic, were analyzed for the presence of several pesticides to which the plastic may have been exposed. Although a variety of alkanes, alkenes, and aromatic and polycyclic aromatic hydrocarbon (PAH) compounds were identified in the volatile, semi-volatile, and particulate fractions of these emissions, a substantial fraction of higher molecular weight organic material was not identified. No pesticides were identified in either combustion emission samples or dichloromethane washes of the used plastic. When mutagenicity was evaluated by exposing Salmonella bacteria (Ames assay) to whole vapor and vapor/particulate emissions, no toxic or mutagenic effects were observed. However, organic extracts of the particulate samples were moderately mutagenic. This mutagenicity compares approximately to that measured from residential wood heating on a revertant per unit heat release basis. Compared to pile burning, forced air slightly decreased the time necessary to burn a charge of plastic. There was not a substantial difference, however, in the variety or concentrations of organic compounds identified in samples from these two burn conditions. This study highlights the benefits of a combined chemical/biological approach to the characterization of complex, multi-component combustion emissions. These results may not reflect those of other types of plastic that may be used

Multi-Point Combustion System: Final Report

Science.gov (United States)

Goeke, Jerry; Pack, Spencer; Zink, Gregory; Ryon, Jason

2014-01-01

A low-NOx emission combustor concept has been developed for NASA's Environmentally Responsible Aircraft (ERA) program to meet N+2 emissions goals for a 70,000 lb thrust engine application. These goals include 75 percent reduction of LTO NOx from CAEP6 standards without increasing CO, UHC, or smoke from that of current state of the art. An additional key factor in this work is to improve lean combustion stability over that of previous work performed on similar technology in the early 2000s. The purpose of this paper is to present the final report for the NASA contract. This work included the design, analysis, and test of a multi-point combustion system. All design work was based on the results of Computational Fluid Dynamics modeling with the end results tested on a medium pressure combustion rig at the UC and a medium pressure combustion rig at GRC. The theories behind the designs, results of analysis, and experimental test data will be discussed in this report. The combustion system consists of five radially staged rows of injectors, where ten small scale injectors are used in place of a single traditional nozzle. Major accomplishments of the current work include the design of a Multipoint Lean Direct Injection (MLDI) array and associated air blast and pilot fuel injectors, which is expected to meet or exceed the goal of a 75 percent reduction in LTO NOx from CAEP6 standards. This design incorporates a reduced number of injectors over previous multipoint designs, simplified and lightweight components, and a very compact combustor section. Additional outcomes of the program are validation that the design of these combustion systems can be aided by the use of Computational Fluid Dynamics to predict and reduce emissions. Furthermore, the staging of fuel through the individually controlled radially staged injector rows successfully demonstrated improved low power operability as well as improvements in emissions over previous multipoint designs. Additional comparison

76 FR 16646 - Circadian, Inc., Clean Energy Combustion, Inc. (n/k/a Clean Energy Combustion Systems, Inc...

Science.gov (United States)

2011-03-24

... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] Circadian, Inc., Clean Energy Combustion, Inc. (n/k/a Clean Energy Combustion Systems, Inc.), Collectible Concepts Group, Inc., Communitronics of... is a lack of current and accurate information concerning the securities of Clean Energy Combustion...

High resolution real time capable combustion chamber simulation; Zeitlich hochaufloesende echtzeitfaehige Brennraumsimulation

Energy Technology Data Exchange (ETDEWEB)

Piewek, J. [Volkswagen AG, Wolfsburg (Germany)

2008-07-01

The article describes a zero-dimensional model for the real time capable combustion chamber pressure calculation with analogue pressure sensor output. The closed-loop-operation of an Engine Control Unit is shown at the hardware-in-the-loop-simulator (HiL simulator) for a 4-cylinder common rail diesel engine. The presentation of the model focuses on the simulation of the load variation which does not depend on the injection system and thus the simulated heat release rate. Particular attention is paid to the simulation and the resulting test possibilities regarding to full-variable valve gears. It is shown that black box models consisting in the HiL mean value model for the aspirated gas mass, the exhaust gas temperature after the outlet valve and the mean indicated pressure can be replaced by calculations from the high-resolution combustion chamber model. (orig.)

75 FR 32142 - Combustible Dust

Science.gov (United States)

2010-06-07

.... Contact Mat Chibbaro, P.E., Fire Protection Engineer, Office of Safety Systems, OSHA Directorate of..., and metals (such as aluminum and magnesium). Industries that may have combustible dust hazards include..., chemical manufacturing, textile manufacturing, furniture manufacturing, metal processing, fabricated metal...

Closed-loop System Identification with New Sensors

DEFF Research Database (Denmark)

Bendtsen, Jan Dimon; Trangbæk, K; Stoustrup, Jakob

2008-01-01

This paper deals with system identification of new system dynamics revealed by online introduction of new sensors in existing multi-variable linear control systems. The so-called "Hansen Scheme" utilises the dual Youla-Kucera parameterisation of all systems stabilised by a given linear controller...... to transform closed-loop system identification problems into open-loop-like problems. We show that this scheme can be formally extended to accomodate extra sensors in a nice way. The approach is illustrated on a simple simulation example....

Numerical Analysis of Combined Well and Open-Closed Loops Geothermal (CWG) Systems

Science.gov (United States)

Park, Yu-Chul

2016-04-01

Open-loop geothermal heat pump (GHP) system and closed-loop heat pump systems have been used in Korea to reduce emission of greenhouse gases such as carbon dioxide (CO2). The GHP systems have the pros and cons, for example, the open-loop GHP system is good energy-efficient and the closed-loop GHP system requires minimum maintenance costs. The open-loop GHP system can be used practically only with large amount of groundwater supply. The closed-loop GHP system can be used with high costs of initial installation. The performance and efficiency of the GHP system depend on the characteristics of the GHP system itself in addition to the geologic conditions. To overcome the cons of open-loop or closed-loop GHP system, the combined well and open-closed loops geothermal (CWG) system was designed. The open-loop GHP system is surrounded with closed-loop GHP systems in the CWG system. The geothermal energy in closed-loop GHP systems is supplied by the groundwater pumped by the open-loop GHP system. In this study, 2 different types of the CWG systems (small aperture hybrid CWG system and large aperture CWG system) are estimated using numerical simulation models in the aspect of energy efficiency. This work was supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea. (No.20153030111120).

Experimental validation of combustion control with multi-pulse fuel injection

NARCIS (Netherlands)

Luo, X.; Velayutham, S.; Willems, F.P.T.

2017-01-01

Closed-loop combustion control helps to achieve precise fuel injection and robust engine performance against disturbances. The controller design complexity increases greatly with larger number of fuel injection pulses due to the coupled influence of changing individual pulse on the combustion

Robust Multivariable Feedback Control of Natural Gas-Diesel RCCI Combustion

NARCIS (Netherlands)

Indrajuana, A.; Bekdemir, C.; Luo, X.; Willems, F.P.T.

2016-01-01

Advanced combustion concepts such as Reactivity Controlled Compression Ignition (RCCI) demonstrate very high thermal efficiencies combined with ultra low NOx emissions. As RCCI is sensitive for operating conditions, closed-loop control is a crucial enabler for stable and robust combustion. The

N2O formation in combustion systems

International Nuclear Information System (INIS)

1989-11-01

The objective of this project is to characterize N 2 O emissions from combustion sources emphasizing N 2 O emissions from post-combustion selective gas phase NO x reduction processes and reburning. The processes to be evaluated include ammonia, urea and cyanuric acid injection and reburning. The project includes pilot-scale testing at two facilities supported by chemical kinetic modeling. Testing will be performed on both a gas-fired plug flow combustor and a pulverized-coal fired combustor. Work performed to date has included the performance of the initial detailed chemical kinetics calculations. These calculations showed that both urea and cyanuric acid produce significant quantities of N 2 O, while NH 3 injection produced negligible amounts. These kinetics data support limited test results reported for cyanuric acid and ammonia injection. Laboratory work to evaluate the selective gas phase NO x reduction processes listed above will begin in the gas-fired facility early in CY 1990. Testing to evaluate reburning at the coal-fired facility is currently planned to be performed in parallel with the testing at the gas-fired facility. Following completion of that work, additional kinetics calculations will be performed

Integrable systems and loop coproducts

International Nuclear Information System (INIS)

Musso, Fabio

2010-01-01

We present a generalization of a framework for the construction of classical integrable systems that we call loop coproduct formulation (Musso 2010 J. Phys. A: Math. Theor. 43 434026). In this paper, the loop coproduct formulation includes systems of Gelfand-Tsetlin type, the linear r-matrix formulation, the Sklyanin algebras, the reflection algebras, the coalgebra symmetry approach and some of its generalizations as particular cases, showing that all these apparently different approaches have a common algebraic origin. On the other hand, all these subcases do not exhaust the domain of applicability of this new technique, so that new possible directions of investigation do naturally emerge in this framework.

Flame blowout and pollutant emissions in vitiated combustion of conventional and bio-derived fuels

Science.gov (United States)

Singh, Bhupinder

The widening gap between the demand and supply of fossil fuels has catalyzed the exploration of alternative sources of energy. Interest in the power, water extraction and refrigeration (PoWER) cycle, proposed by the University of Florida, as well as the desirability of using biofuels in distributed generation systems, has motivated the exploration of biofuel vitiated combustion. The PoWER cycle is a novel engine cycle concept that utilizes vitiation of the air stream with externally-cooled recirculated exhaust gases at an intermediate pressure in a semi-closed cycle (SCC) loop, lowering the overall temperature of combustion. It has several advantages including fuel flexibility, reduced air flow, lower flame temperature, compactness, high efficiency at full and part load, and low emissions. Since the core engine air stream is vitiated with the externally cooled exhaust gas recirculation (EGR) stream, there is an inherent reduction in the combustion stability for a PoWER engine. The effect of EGR flow and temperature on combustion blowout stability and emissions during vitiated biofuel combustion has been characterized. The vitiated combustion performance of biofuels methyl butanoate, dimethyl ether, and ethanol have been compared with n-heptane, and varying compositions of syngas with methane fuel. In addition, at high levels of EGR a sharp reduction in the flame luminosity has been observed in our experimental tests, indicating the onset of flameless combustion. This drop in luminosity may be a result of inhibition of processes leading to the formation of radiative soot particles. One of the objectives of this study is finding the effect of EGR on soot formation, with the ultimate objective of being able to predict the boundaries of flameless combustion. Detailed chemical kinetic simulations were performed using a constant-pressure continuously stirred tank reactor (CSTR) network model developed using the Cantera combustion code, implemented in C++. Results have

Manifold methods for methane combustion

Energy Technology Data Exchange (ETDEWEB)

Yang, B.; Pope, S.B. [Cornell Univ., Ithaca, NY (United States)

1995-10-01

Great progresses have been made in combustion research, especially, the computation of laminar flames and the probability density function (PDF) method in turbulent combustion. For one-dimensional laminar flames, by considering the transport mechanism, the detailed chemical kinetic mechanism and the interactions between these two basic processes, today it is a routine matter to calculate flame velocities, extinction, ignition, temperature, and species distributions from the governing equations. Results are in good agreement with those obtained for experiments. However, for turbulent combustion, because of the complexities of turbulent flow, chemical reactions, and the interaction between them, in the foreseeable future, it is impossible to calculate the combustion flow field by directly integrating the basic governing equations. So averaging and modeling are necessary in turbulent combustion studies. Averaging, on one hand, simplifies turbulent combustion calculations, on the other hand, it introduces the infamous closure problems, especially the closure problem with chemical reaction terms. Since in PDF calculations of turbulent combustion, the averages of the chemical reaction terms can be calculated, PDF methods overcome the closure problem with the reaction terms. It has been shown that the PDF method is a most promising method to calculate turbulent combustion. PDF methods have been successfully employed to calculate laboratory turbulent flames: they can predict phenomena such as super equilibrium radical levels, and local extinction. Because of these advantages, PDF methods are becoming used increasingly in industry combustor codes.

Dry low NOx combustion system with pre-mixed direct-injection secondary fuel nozzle

Science.gov (United States)

Zuo, Baifang; Johnson, Thomas; Ziminsky, Willy; Khan, Abdul

2013-12-17

A combustion system includes a first combustion chamber and a second combustion chamber. The second combustion chamber is positioned downstream of the first combustion chamber. The combustion system also includes a pre-mixed, direct-injection secondary fuel nozzle. The pre-mixed, direct-injection secondary fuel nozzle extends through the first combustion chamber into the second combustion chamber.

Hyperchaos and chaotic hierarchy in low-dimensional chemical systems

Science.gov (United States)

Baier, Gerold; Sahle, Sven

1994-06-01

Chemical reaction chains with feedback of one of the products on the source of the chain are considered. A strategy is presented in terms of ordinary differential equations which creates one, two, and three positive Lyapunov exponents as the finite dimension of the system is increased. In particular, a nonlinear inhibition loop in a chemical reaction sequence controls the type of chaos. The bifurcation scenarios are studied and chaos and hyperchaos are found for broad regions of bifurcation parameter. Some implications for the occurrence of higher chaos in real systems are discussed.

An Integrated Photoelectrochemical-Chemical Loop for Solar-Driven Overall Splitting of Hydrogen Sulfide

DEFF Research Database (Denmark)

Zong, Xu; Han, Jingfeng; Seger, Brian

2014-01-01

Abundant and toxic hydrogen sulfide (H2S) from industry and nature has been traditionally considered a liability. However, it represents a potential resource if valuable H-2 and elemental sulfur can be simultaneously extracted through a H2S splitting reaction. Herein a photochemical-chemical loop...... simulated solar light. This new conceptual design will not only provide a possible route for using solar energy to convert H2S into valuable resources, but also sheds light on some challenging photochemical reactions such as CH4 activation and CO2 reduction.......Abundant and toxic hydrogen sulfide (H2S) from industry and nature has been traditionally considered a liability. However, it represents a potential resource if valuable H-2 and elemental sulfur can be simultaneously extracted through a H2S splitting reaction. Herein a photochemical-chemical loop...... linked by redox couples such as Fe2+/Fe3+ and I-/I-3(-) for photoelectrochemical H-2 production and H2S chemical absorption redox reactions are reported. Using functionalized Si as photoelectrodes, H2S was successfully split into elemental sulfur and H-2 with high stability and selectivity under...

Numerical analysis on the combustion and emission characteristics of forced swirl combustion system for DI diesel engines

International Nuclear Information System (INIS)

Su, LiWang; Li, XiangRong; Zhang, Zheng; Liu, FuShui

2014-01-01

Highlights: • A new combustion system named FSCS for DI diesel engines was proposed. • Fuel/air mixture formation was improved for the application of FSCS. • The FSCS showed a good performance on emission characteristics. - Abstract: To optimize the fuel/air mixture formation and improve the environmental effect of direct injection (DI) diesel engines, a new forced swirl combustion system (FSCS) was proposed concerned on unique design of the geometric shape of the combustion chamber. Numerical simulation was conducted to verify the combustion and emission characteristics of the engines with FSCS. The fuel/air diffusion, in-cylinder velocity distribution, turbulent kinetic energy and in-cylinder temperature distribution were analyzed and the results shown that the FSCS can increase the area of fuel/air diffusion and improve the combustion. The diesel engine with FSCS also shown excellent performance on emission. At full load condition, the soot emission was significantly reduced for the improved fuel/air mixture formation. There are slightly difference for the soot and NO emission between the FSCS and the traditional omega combustion system at lower load for the short penetration of the fuel spray

A comprehensive study of combustion products generated from pulverized peat combustion in the furnace of BKZ-210-140F steam boiler

Science.gov (United States)

Kuzmin, V. A.; Zagrai, I. A.

2017-11-01

The experimental and theoretical study of combustion products has been carried out for the conditions of pulverized peat combustion in BKZ-210-140F steam boiler. Sampling has been performed in different parts of the boiler system in order to determine the chemical composition, radiative properties and dispersity of slag and ash particles. The chemical composition of particles was determined using the method of x-ray fluorescence analysis. Shapes and sizes of the particles were determined by means of electron scanning microscopy. The histograms and the particle size distribution functions were computed. The calculation of components of the gaseous phase was based on the combustion characteristics of the original fuel. The software package of calculation of thermal radiation of combustion products from peat combustion was used to simulate emission characteristics (flux densities and emissivity factors). The dependence of emission characteristics on the temperature level and on the wavelength has been defined. On the basis of the analysis of emission characteristics the authors give some recommendations how to determine the temperature of peat combustion products in the furnace of BKZ-210-140F steam boiler. The findings can be used to measure the combustion products temperature, support temperature control in peat combustion and solve the problem of boiler furnace slagging.

Physical and chemical effects of low octane gasoline fuels on compression ignition combustion

KAUST Repository

Badra, Jihad

2016-09-30

Gasoline compression ignition (GCI) engines running on low octane gasoline fuels are considered an attractive alternative to traditional spark ignition engines. In this study, three fuels with different chemical and physical characteristics have been investigated in single cylinder engine running in GCI combustion mode at part-load conditions both experimentally and numerically. The studied fuels are: Saudi Aramco light naphtha (SALN) (Research octane number (RON) = 62 and final boiling point (FBP) = 91 °C), Haltermann straight run naphtha (HSRN) (RON = 60 and FBP = 140 °C) and a primary reference fuel (PRF65) (RON = 65 and FBP = 99 °C). Injection sweeps, where the start of injection (SOI) is changed between −60 and −11 CAD aTDC, have been performed for the three fuels. Full cycle computational fluid dynamics (CFD) simulations were executed using PRFs as chemical surrogates for the naphtha fuels. Physical surrogates based on the evaporation characteristics of the naphtha streams have been developed and their properties have been implemented in the engine simulations. It was found that the three fuels have similar combustion phasings and emissions at the conditions tested in this work with minor differences at SOI earlier than −30 CAD aTDC. These trends were successfully reproduced by the CFD calculations. The chemical and physical effects were further investigated numerically. It was found that the physical characteristics of the fuel significantly affect the combustion for injections earlier than −30 CAD aTDC because of the low evaporation rates of the fuel because of the higher boiling temperature of the fuel and the colder in-cylinder air during injection. © 2016 Elsevier Ltd

Study of physico-chemical release of uranium and plutonium oxides during the combustion of polycarbonate and of ruthenium during the combustion of solvents used in the reprocessing of nuclear fuel; Etude de la mise en suspension physico-chimique des oxydes de plutonium et d'uranium lors de la combustion de polycarbonate et de ruthenium lors de la combustion des solvants de retraitement du combustible irradie

Energy Technology Data Exchange (ETDEWEB)

Bouilloux, L

1998-07-01

The level of consequences concerning a fire in a nuclear facility is in part estimated by the quantities and the physico-chemical forms of radioactive compounds that may be emitted out of the facility. It is therefore necessary to study the contaminant release from the fire. Because of the multiplicity of the scenarios, two research subjects were retained. The first one concerns the study of the uranium or plutonium oxides chemical release during the combustion of the polycarbonate glove box sides. The second one is about the physico chemical characterisation of the ruthenium release during the combustion of an organic solvent mixture (tributyl phosphate-dodecane) used for the nuclear fuel reprocessing. Concerning the two research subjects, the chemical release, i.e. means the generation of contaminant compounds gaseous in the fire, was modelled using thermodynamical simulations. Experiments were done in order to determine the ruthenium release factor during solvent combustion. A cone calorimeter was used for small scale experiments. These results were then validated by large scale tests under conditions close to the industrial process. Thermodynamical simulations, for the two scenarios studied. Furthermore, the experiments on solvent combustion allowed the determination of a suitable ruthenium release factor. Finally, the mechanism responsible of the ruthenium release has been found. (author)

Pulsating combustion - Combustion characteristics and reduction of emissions

Energy Technology Data Exchange (ETDEWEB)

Lindholm, Annika

1999-11-01

In the search for high efficiency combustion systems pulsating combustion has been identified as one of the technologies that potentially can meet the objectives of clean combustion and good fuel economy. Pulsating combustion offers low emissions of pollutants, high heat transfer and efficient combustion. Although it is an old technology, the interest in pulsating combustion has been renewed in recent years, due to its unique features. Various applications of pulsating combustion can be found, mainly as drying and heating devices, of which the latter also have had commercial success. It is, however, in the design process of a pulse combustor, difficult to predict the operating frequency, the heat release etc., due to the lack of a well founded theory of the phenomenon. Research concerning control over the combustion process is essential for developing high efficiency pulse combustors with low emissions. Natural gas fired Helmholtz type pulse combustors have been the experimental objects of this study. In order to investigate the interaction between the fluid dynamics and the chemistry in pulse combustors, laser based measuring techniques as well as other conventional measuring techniques have been used. The experimental results shows the possibilities to control the combustion characteristics of pulsating combustion. It is shown that the time scales in the large vortices created at the inlet to the combustion chamber are very important for the operation of the pulse combustor. By increasing/decreasing the time scale for the large scale mixing the timing of the heat release is changed and the operating characteristics of the pulse combustor changes. Three different means for NO{sub x} reduction in Helmholtz type pulse combustors have been investigated. These include exhaust gas recirculation, alteration of air/fuel ratio and changed inlet geometry in the combustion chamber. All used methods achieved less than 10 ppm NO{sub x} emitted (referred to stoichiometric

Physico-chemical and optical properties of combustion-generated particles from coal-fired power plant, automobile and ship engine and charcoal kiln.

Science.gov (United States)

Kim, Hwajin

2015-04-01

Similarities and differences in physico-chemical and optical properties of combustion generated particles from various sources were investigated. Coal-fired power plant, charcoal kiln, automobile and ship engine were major sources, representing combustions of coal, biomass and two different types of diesel, respectively. Scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDX) equipped with both SEM and HRTEM were used for physico-chemical analysis. Light absorbing properties were assessed using a spectrometer equipped with an integrating sphere. Particles generated from different combustion sources and conditions demonstrate great variability in their morphology, structure and composition. From coal-fired power plant, both fly ash and flue gas were mostly composed of heterogeneously mixed mineral ash spheres, suggesting that the complete combustion was occurred releasing carbonaceous species out at high temperature (1200-1300 °C). Both automobile and ship exhausts from diesel combustions show typical features of soot: concentric circles comprised of closely-packed graphene layers. However, heavy fuel oil (HFO) combusted particles from ship exhaust demonstrate more complex compositions containing different morphology of particles other than soot, e.g., spherical shape of char particles composed of minerals and carbon. Even for the soot aggregates, particles from HFO burning have different chemical compositions; carbon is dominated but Ca (29.8%), S (28.7%), Na(1%), and Mg(1%) are contained, respectively which were not found from particles of automobile emission. This indicates that chemical compositions and burning conditions are significant to determine the fate of particles. Finally, from biomass burning, amorphous and droplet-like carbonaceous particles with no crystallite structure are observed and they are generally formed by the condensation of low volatile species at low

Assessment of Literature Related to Combustion Appliance Venting Systems

Energy Technology Data Exchange (ETDEWEB)

Rapp, V. H.; Less, B. D.; Singer, B. C.; Stratton, J. C.; Wray, C. P.

2015-02-01

In many residential building retrofit programs, air tightening to increase energy efficiency is often constrained by safety concerns with naturally vented combustion appliances. Tighter residential buildings more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft or spill combustion exhaust into the living space. Several measures, such as installation guidelines, vent sizing codes, and combustion safety diagnostics, are in place with the intent to prevent backdrafting and combustion spillage, but the diagnostics conflict and the risk mitigation objective is inconsistent. This literature review summarizes the metrics and diagnostics used to assess combustion safety, documents their technical basis, and investigates their risk mitigations. It compiles information from the following: codes for combustion appliance venting and installation; standards and guidelines for combustion safety diagnostics; research evaluating combustion safety diagnostics; research investigating wind effects on building depressurization and venting; and software for simulating vent system performance.

Analysis of Chemical Reaction Kinetics Behavior of Nitrogen Oxide During Air-staged Combustion in Pulverized Boiler

Directory of Open Access Journals (Sweden)

Jun-Xia Zhang

2016-03-01

Full Text Available Because the air-staged combustion technology is one of the key technologies with low investment running costs and high emission reduction efficiency for the pulverized boiler, it is important to reveal the chemical reaction kinetics mechanism for developing various technologies of nitrogen oxide reduction emissions. At the present work, a three-dimensional mesh model of the large-scale four corner tangentially fired boiler furnace is established with the GAMBIT pre-processing of the FLUENT software. The partial turbulent premixed and diffusion flame was simulated for the air-staged combustion processing. Parameters distributions for the air-staged and no the air-staged were obtained, including in-furnace flow field, temperature field and nitrogen oxide concentration field. The results show that the air-staged has more regular velocity field, higher velocity of flue gas, higher turbulence intensity and more uniform temperature of flue gas. In addition, a lower negative pressure zone and lower O2 concentration zone is formed in the main combustion zone, which is conducive to the NO of fuel type reduced to N2, enhanced the effect of NOx reduction. Copyright © 2016 BCREC GROUP. All rights reserved Received: 5th November 2015; Revised: 14th January 2016; Accepted: 16th January 2016  How to Cite: Zhang, J.X., Zhang, J.F. (2016. Analysis of Chemical Reaction Kinetics Behavior of Nitrogen Oxide During Air-staged Combustion in Pulverized Boiler. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 100-108. (doi:10.9767/bcrec.11.1.431.100-108 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.431.100-108

Combustion from basics to applications

CERN Document Server

Lackner, Maximilian; Winter, Franz

2013-01-01

Combustion, the process of burning, is defined as a chemical reaction between a combustible reactant (the fuel) and an oxidizing agent (such as air) in order to produce heat and in most cases light while new chemical species (e.g., flue gas components) are formed. This book covers a gap on the market by providing a concise introduction to combustion. Most of the other books currently available are targeted towards the experienced users and contain too many details and/or contain knowledge at a fairly high level. This book provides a brief and clear overview of the combustion basics, suitable f

In situ high-temperature gas sensors: continuous monitoring of the combustion quality of different wood combustion systems and optimization of combustion process

Directory of Open Access Journals (Sweden)

H. Kohler

2018-03-01

Full Text Available The sensing characteristics and long-term stability of different kinds of CO ∕ HC gas sensors (non-Nernstian mixed potential type during in situ operation in flue gas from different types of low-power combustion systems (wood-log- and wood-chip-fuelled were investigated. The sensors showed representative but individual sensing behaviour with respect to characteristically varying flue gas composition over the combustion process. The long-term sensor signal stability evaluated by repeated exposure to CO ∕ H2 ∕ N2 ∕ synthetic air mixtures showed no sensitivity loss after operation in the flue gas. Particularly for one of the sensors (Heraeus GmbH, this high signal stability was observed in a field test experiment even during continuous operation in the flue gas of the wood-chip firing system over 4 months. Furthermore, it was experimentally shown that the signals of these CO ∕ HC sensing elements yield important additional information about the wood combustion process. This was demonstrated by the adaptation of an advanced combustion airstream control algorithm on a wood-log-fed fireplace and by the development of a combustion quality monitoring system for wood-chip-fed central heaters.

Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

Science.gov (United States)

Berry, G.F.; Minkov, V.; Petrick, M.

1981-11-02

A magnetohydrodynamic (MHD) power generating system is described in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

Prediction of Non-Equilibrium Kinetics of Fuel-Rich Kerosene/LOX Combustion in Gas Generator

International Nuclear Information System (INIS)

Yu, Jung Min; Lee, Chang Jin

2007-01-01

Gas generator is the device to produce high enthalpy gases needed to drive turbo-pump system in liquid rocket engine. And, the combustion temperature in gas generator should be controlled below around 1,000K to avoid any possible thermal damages to turbine blade by using either fuel rich combustion or oxidizer rich combustion. Thus, nonequilibrium chemical reaction dominates in fuel-rich combustion of gas generator. Meanwhile, kerosene is a compounded fuel with various types of hydrocarbon elements and difficult to model the chemical kinetics. This study focuses on the prediction of the non-equilibrium reaction of fuel rich kerosene/LOX combustion with detailed kinetics developed by Dagaut using PSR (Perfectly Stirred Reactor) assumption. In Dagaut's surrogate model for kerosene, chemical kinetics of kerosene consists of 1,592 reaction steps with 207 chemical species. Also, droplet evaporation time is taken into account in the PSR calculation by changing the residence time of droplet in the gas generator. Frenklach's soot model was implemented along with detailed kinetics to calculate the gas properties of fuel rich combustion efflux. The results could provide very reliable and accurate numbers in the prediction of combustion gas temperature,species fraction and material properties

Operator decision support system for sodium loop

Energy Technology Data Exchange (ETDEWEB)

Lee, Kwang Hyeang; Park, Kyu Ho; Kim, Tak Kon; Jo, Choong Ho; Seong, Kyeong A; Lee, Keon Myeong; Kim, Yeong Dal; Kim, Chang Beom; Kim, Jong Kyu; Jo, Hee Chang; Lee, Ji Hyeong; Jeong, Yoon Soo; Chio, Jong Hyeong; Jeong, Bong Joon; Hong, Joon Seong; Kim, Bong Wan; Seong, Byeong Hak [Korea Advanced Institute Science and Technology, Taejon (Korea, Republic of)

1994-07-01

The objective of this study is to develop an operator decision support system by computerizing the sodium circuit. This study developed graphical display interface for the control panel which provides the safety control of equipment, the recognition of experimental process states and sodium circuit states. In this study, basic work to develop an operator decision support real-time expert system for sodium loop was carried out. Simplification of control commands and effective operation of various real-time data and signals by equipment code standardization are studied. The cost ineffectiveness of the single processor structure provides the ground for the development of cost effective parallel processing system. The important tasks of this study are (1) design and implementation of control state surveillance panel of sodium loop, (2) requirement analysis of operator support real-time expert system for sodium loop, (3) design of standard code rule for operating equipment and research on the cost effective all purpose parallel processing system and (4) requirement analysis of expert system and design of control state variables and user interface for experimental process. 10 refs., 36 figs., 20 tabs.

System and method for reducing combustion dynamics in a combustor

Science.gov (United States)

Uhm, Jong Ho; Ziminsky, Willy Steve; Johnson, Thomas Edward; Srinivasan, Shiva; York, William David

2016-11-29

A system for reducing combustion dynamics in a combustor includes an end cap that extends radially across the combustor and includes an upstream surface axially separated from a downstream surface. A combustion chamber is downstream of the end cap, and tubes extend from the upstream surface through the downstream surface. Each tube provides fluid communication through the end cap to the combustion chamber. The system further includes means for reducing combustion dynamics in the combustor. A method for reducing combustion dynamics in a combustor includes flowing a working fluid through tubes that extend axially through an end cap that extends radially across the combustor and obstructing at least a portion of the working fluid flowing through a first set of the tubes.

Numerical investigation of a straw combustion boiler – Part I: Modelling of the thermo-chemical conversion of straw

Directory of Open Access Journals (Sweden)

Dernbecher Andrea

2016-01-01

Full Text Available In the framework of a European project, a straw combustion boiler in conjunction with an organic Rankine cycle is developed. One objective of the project is the enhancement of the combustion chamber by numerical methods. A comprehensive simulation of the combustion chamber is prepared, which contains the necessary submodels for the thermo-chemical conversion of straw and for the homogeneous gas phase reactions. Part I introduces the modelling approach for the thermal decomposition of the biomass inside the fuel bed, whereas part II deals with the simulation of the gas phase reactions in the freeboard.

Alstom's development of advanced CFB based technologies for CO{sub 2} mitigation

Energy Technology Data Exchange (ETDEWEB)

Nsakala ya Nsakala; David G. Turek; Gregory N. Liljedahl; Herbert E. Andrus; John H. Chiu; Jean-Xavier Morin [Alstom Power Inc., Windsor, CT (United States)

2005-07-01

ALSTOM Power Inc. (ALSTOM) is actively working to develop advanced circulating fluidized bed (CFB) based technologies for the purpose of CO{sub 2} mitigation. Two of the more promising ideas currently being investigated at ALSTOM are the oxygen-fired CFB and chemical looping technologies. The oxygen-fired CFB is a near-term CO{sub 2} capture technology, which uses pure oxygen tempered with recirculated flue gas to combust the fuel. The oxygen for combustion may be supplied by a cryogenic air separation unit, or in the future by more efficient processes such as oxygen transport membrane. This produces a flue gas stream comprising mostly CO{sub 2} and water vapor. Simple condensation of most of the water vapor leaves a CO{sub 2}-rich product stream which can be simply compressed for sequestration or purified for use in enhanced oil recovery or enhanced coal bed methane. Chemical looping is a longer-term development path towards CO{sub 2} mitigation. In ALSTOM's processes, a regenerable solid carrier extracts oxygen from air and transports it for combustion or gasification of the fuel. The chemical looping combustion process produces a high CO{sub 2} flue gas stream (similar to the O{sub 2} fired CFB flue gas stream) and steam for a Rankine cycle. The chemical looping gasification process captures CO{sub 2} in a separate chemical loop and produces hydrogen-rich synthesis gas for use in IGCCs, fuel cells, or for other industrial uses. This paper discusses ALSTOM's latest test work in these areas and the technical, economic and environmental implications of these advanced CFB-based systems. These advanced power generation units can be built from proven fluid bed design features and systems. 6 refs., 15 figs., 6 tabs.

Efficient energy recovering air inlet system for an internal combustion engine

NARCIS (Netherlands)

2011-01-01

An air inlet system (10) for an internal combustion engine (200) is provided. The air inlet system comprises an air intake port (20), an air output port (30) for providing air for a combustion chamber (202) of the combustion engine (200), and a turbine (40). The turbine (40) is situated in between

Efficient energy recovering air inlet system for an international combustion engine

NARCIS (Netherlands)

2013-01-01

An air inlet system (10) for an internal combustion engine (200) is provided. The air inlet system comprises an air intake port (20), an air output port (30) for providing air for a combustion chamber (202) of the combustion engine (200), and a turbine (40). The turbine (40) is situated in between

Sorbent control of trace metals in sewage sludge combustion and incineration

Science.gov (United States)

Naruse, I.; Yao, H.; Mkilaha, I. S. N.

2003-05-01

Coal and wastes combustion have become an important issue not only in terms of energy generation but also environmental conservation. The need for alternative fuels and wastes management has made the two energy sources of importance. However, the utilization of the two is faced with problems of impurity trace metals in the fuel. These metals usually speciate during combustion or incineration leading to generation of fumes and subsequently particles. This paper reports on the study aimed at understanding the speciation of trace metals and their emission from combustion systems as particulates. Experiments carried out using a down-flow furnace and theoretical study carried out using lead, chromium and cadmium as basic metals had shown that their speciation and subsequent emission is controlled by both chemical composition and physical properties of the fuel. The physical and chemical and physical properties of the fuel and their respective compounds and the operating conditions of the incineration and combustion system control the enrichment of the particles with trace metals.

Fundamental characterization of alternate fuel effects in continuous combustion systems

Energy Technology Data Exchange (ETDEWEB)

Blazowski, W.S.; Edelman, R.B.; Harsha, P.T.

1978-09-11

The overall objective of this contract is to assist in the development of fuel-flexible combustion systems for gas turbines as well as Rankine and Stirling cycle engines. The primary emphasis of the program is on liquid hydrocarbons produced from non-petroleum resouces. Fuel-flexible combustion systems will provide for more rapid transition of these alternate fuels into important future energy utilization centers (especially utility power generation with the combined cycle gas turbine). The specific technical objectives of the program are to develop an improved understanding of relationships between alternate fuel properties and continuous combustion system effects, and to provide analytical modeling/correlation capabilities to be used as design aids for development of fuel-tolerant combustion systems. Efforts this past year have been to evaluate experimental procedures for studying alternate fuel combustion effects and to determine current analytical capabilities for prediction of these effects. Jet Stirred Combustor studies during this period have produced new insights into soot formation in strongly backmixed systems and have provided much information for comparison with analytical predictions. The analytical effort included new applications of quasi-global modeling techniques as well as comparison of prediction with the experimental results generated.

Reduced chemical kinetic mechanisms for NOx emission prediction in biomass combustion

DEFF Research Database (Denmark)

Houshfar, Ehsan; Skreiberg, Øyvind; Glarborg, Peter

2012-01-01

Because of the complex composition of biomass, the chemical mechanism contains many different species and therefore a large number of reactions. Although biomass gas‐phase combustion is fairly well researched and understood, the proposed mechanisms are still complex and need very long computational...... time and powerful hardware resources. A reduction of the mechanism for biomass volatile oxidation has therefore been performed to avoid these difficulties. The selected detailed mechanism in this study contains 81 species and 703 elementary reactions. Necessity analysis is used to determine which...... reactions and chemical species, that is, 35 species and 198 reactions, corresponding to 72% reduction in the number of reactions and, therefore, improving the computational time considerably. Yet, the model based on the reduced mechanism predicts correctly concentrations of NOx and CO that are essentially...

An Experimental and Chemical Kinetics Study of the Combustion of Syngas and High Hydrogen Content Fuels

Energy Technology Data Exchange (ETDEWEB)

Santoro, Robers [Pennsylvania State Univ., State College, PA (United States); Dryer, Frederick [Princeton Univ., NJ (United States); Ju, Yiguang [Princeton Univ., NJ (United States)

2013-09-30

An integrated and collaborative effort involving experiments and complementary chemical kinetic modeling investigated the effects of significant concentrations of water and CO2 and minor contaminant species (methane [CH4], ethane [C2H6], NOX, etc.) on the ignition and combustion of HHC fuels. The research effort specifically addressed broadening the experimental data base for ignition delay, burning rate, and oxidation kinetics at high pressures, and further refinement of chemical kinetic models so as to develop compositional specifications related to the above major and minor species. The foundation for the chemical kinetic modeling was the well validated mechanism for hydrogen and carbon monoxide developed over the last 25 years by Professor Frederick Dryer and his co-workers at Princeton University. This research furthered advance the understanding needed to develop practical guidelines for realistic composition limits and operating characteristics for HHC fuels. A suite of experiments was utilized that that involved a high-pressure laminar flow reactor, a pressure-release type high-pressure combustion chamber and a high-pressure turbulent flow reactor.

Assessment of Literature Related to Combustion Appliance Venting Systems

Energy Technology Data Exchange (ETDEWEB)

Rapp, Vi H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Singer, Brett C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Stratton, Chris [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wray, Craig P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-06-01

In many residential building retrofit programs, air tightening to increase energy efficiency is constrained by concerns about related impacts on the safety of naturally vented combustion appliances. Tighter housing units more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft or spillage. Several test methods purportedly assess the potential for depressurization-induced backdrafting and spillage, but these tests are not robustly reliable and repeatable predictors of venting performance, in part because they do not fully capture weather effects on venting performance. The purpose of this literature review is to investigate combustion safety diagnostics in existing codes, standards, and guidelines related to combustion appliances. This review summarizes existing combustion safety test methods, evaluations of these test methods, and also discusses research related to wind effects and the simulation of vent system performance. Current codes and standards related to combustion appliance installation provide little information on assessing backdrafting or spillage potential. A substantial amount of research has been conducted to assess combustion appliance backdrafting and spillage test methods, but primarily focuses on comparing short-term (stress) induced tests and monitoring results. Monitoring, typically performed over one week, indicated that combinations of environmental and house operation characteristics most conducive to combustion spillage were rare. Research, to an extent, has assessed existing combustion safety diagnostics for house depressurization, but the objectives of the diagnostics, both stress and monitoring, are not clearly defined. More research is also needed to quantify the frequency of test “failure” occurrence throughout the building stock and assess the statistical effects of weather (especially wind) on house depressurization and in turn on combustion appliance venting

Injection system used into SI engines for complete combustion and reduction of exhaust emissions in the case of alcohol and petrol alcohol mixtures feed

Science.gov (United States)

Ispas, N.; Cofaru, C.; Aleonte, M.

2017-10-01

Internal combustion engines still play a major role in today transportation but increasing the fuel efficiency and decreasing chemical emissions remain a great goal of the researchers. Direct injection and air assisted injection system can improve combustion and can reduce the concentration of the exhaust gas pollutes. Advanced air-to-fuel and combustion air-to-fuel injection system for mixtures, derivatives and alcohol gasoline blends represent a major asset in reducing pollutant emissions and controlling combustion processes in spark-ignition engines. The use of these biofuel and biofuel blending systems for gasoline results in better control of spark ignition engine processes, making combustion as complete as possible, as well as lower levels of concentrations of pollutants in exhaust gases. The main purpose of this paper was to provide most suitable tools for ensure the proven increase in the efficiency of spark ignition engines, making them more environmentally friendly. The conclusions of the paper allow to highlight the paths leading to a better use of alcohols (biofuels) in internal combustion engines of modern transport units.

Chemical composition and speciation of particulate organic matter from modern residential small-scale wood combustion appliances.

Science.gov (United States)

Czech, Hendryk; Miersch, Toni; Orasche, Jürgen; Abbaszade, Gülcin; Sippula, Olli; Tissari, Jarkko; Michalke, Bernhard; Schnelle-Kreis, Jürgen; Streibel, Thorsten; Jokiniemi, Jorma; Zimmermann, Ralf

2018-01-15

Combustion technologies of small-scale wood combustion appliances are continuously developed decrease emissions of various pollutants and increase energy conversion. One strategy to reduce emissions is the implementation of air staging technology in secondary air supply, which became an established technique for modern wood combustion appliances. On that account, emissions from a modern masonry heater fuelled with three types of common logwood (beech, birch and spruce) and a modern pellet boiler fuelled with commercial softwood pellets were investigated, which refer to representative combustion appliances in northern Europe In particular, emphasis was put on the organic constituents of PM2.5, including polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (OPAHs) and phenolic species, by targeted and non-targeted mass spectrometric analysis techniques. Compared to conventional wood stoves and pellet boilers, organic emissions from the modern appliances were reduced by at least one order of magnitude, but to a different extent for single species. Hence, characteristic ratios of emission constituents and emission profiles for wood combustion identification and speciation do not hold for this type of advanced combustion technology. Additionally, an overall substantial reduction of typical wood combustion markers, such as phenolic species and anhydrous sugars, were observed. Finally, it was found that slow ignition of log woods changes the distribution of characteristic resin acids and phytosterols as well as their thermal alteration products, which are used as markers for specific wood types. Our results should be considered for wood combustion identification in positive matrix factorisation or chemical mass balance in northern Europe. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of radiative transfer of heat released from combustion reaction on temperature distribution: A numerical study for a 2-D system

International Nuclear Information System (INIS)

Zhou Huaichun; Ai Yuhua

2006-01-01

Both light and heat are produced during a chemical reaction in a combustion process, but traditionally all the energy released is taken as to be transformed into the internal energy of the combustion medium. So the temperature of the medium increases, and then the thermal radiation emitted from it increases too. Chemiluminescence is generated during a chemical reaction and independent of the temperature, and has been used widely for combustion diagnostics. It was assumed in this paper that the total energy released in a combustion reaction is divided into two parts, one part is a self-absorbed heat, and the other is a directly emitted heat. The former is absorbed immediately by the products, becomes the internal energy and then increases the temperature of the products as treated in the traditional way. The latter is emitted directly as radiation into the combustion domain and should be included in the radiation transfer equation (RTE) as a part of radiation source. For a simple, 2-D, gray, emitting-absorbing, rectangular system, the numerical study showed that the temperatures in reaction zones depended on the fraction of the directly emitted energy, and the smaller the gas absorption coefficient was, the more strong the dependence appeared. Because the effect of the fraction of the directly emitted heat on the temperature distribution in the reacting zones for gas combustion is significant, it is required to conduct experimental measurements to determine the fraction of self-absorbed heat for different combustion processes

Vulnerability Analysis of Urban Drainage Systems: Tree vs. Loop Networks

Directory of Open Access Journals (Sweden)

Chi Zhang

2017-03-01

Full Text Available Vulnerability analysis of urban drainage networks plays an important role in urban flood management. This study analyzes and compares the vulnerability of tree and loop systems under various rainfall events to structural failure represented by pipe blockage. Different pipe blockage scenarios, in which one of the pipes in an urban drainage network is assumed to be blocked individually, are constructed and their impacts on the network are simulated under different storm events. Furthermore, a vulnerability index is defined to measure the vulnerability of the drainage systems before and after the implementation of adaptation measures. The results obtained indicate that the tree systems have a relatively larger proportion of critical hydraulic pipes than the loop systems, thus the vulnerability of tree systems is substantially greater than that of the loop systems. Furthermore, the vulnerability index of tree systems is reduced after they are converted into a loop system with the implementation of adaptation measures. This paper provides an insight into the differences in the vulnerability of tree and loop systems, and provides more evidence for development of adaptation measures (e.g., tanks to reduce urban flooding.

Annual Report: DOE Advanced Combustion Systems & Fuels R&D; Light-Duty Diesel Combustion

Energy Technology Data Exchange (ETDEWEB)

Busch, Stephen [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

2017-11-01

Despite compliance issues in previous years, automakers have demonstrated that the newest generation of diesel power trains are capable of meeting all federal and state regulations (EPA, 2016). Diesels continue to be a cost-effective, efficient, powerful propulsion source for many light- and medium-duty vehicle applications (Martec, 2016). Even modest reductions in the fuel consumption of light- and medium duty diesel vehicles in the U.S. will eliminate millions of tons of CO2 emissions per year. Continued improvement of diesel combustion systems will play an important role in reducing fleet fuel consumption, but these improvements will require an unprecedented scientific understanding of how changes in engine design and calibration affect the mixture preparation, combustion, and pollutant formation processes that take place inside the cylinder. The focus of this year’s research is to provide insight into the physical mechanisms responsible for improved thermal efficiency observed with a stepped-lip piston. Understanding how piston design can influence efficiency will help engineers develop and optimize new diesel combustion systems.

A Triple-Loop Inductive Power Transmission System for Biomedical Applications.

Science.gov (United States)

Lee, Byunghun; Kiani, Mehdi; Ghovanloo, Maysam

2016-02-01

A triple-loop wireless power transmission (WPT) system equipped with closed-loop global power control, adaptive transmitter (Tx) resonance compensation (TRC), and automatic receiver (Rx) resonance tuning (ART) is presented. This system not only opposes coupling and load variations but also compensates for changes in the environment surrounding the inductive link to enhance power transfer efficiency (PTE) in applications such as implantable medical devices (IMDs). The Tx was built around a commercial off-the-shelf (COTS) radio-frequency identification (RFID) reader, operating at 13.56 MHz. A local Tx loop finds the optimal capacitance in parallel with the Tx coil by adjusting a varactor. A global power control loop maintains the received power at a desired level in the presence of changes in coupling distance, coil misalignments, and loading. Moreover, a local Rx loop is implemented inside a power management integrated circuit (PMIC) to avoid PTE degradation due to the Rx coil surrounding environment and process variations. The PMIC was fabricated in a 0.35- μm 4M2P standard CMOS process with 2.54 mm(2) active area. Measurement results show that the proposed triple-loop system improves the overall PTE by up to 10.5% and 4.7% compared to a similar open- and single closed-loop system, respectively, at nominal coil distance of 2 cm. The added TRC and ART loops contribute 2.3% and 1.4% to the overall PTE of 13.5%, respectively. This is the first WPT system to include three loops to dynamically compensate for environment and circuit variations and improve the overall power efficiency all the way from the driver output in Tx to the load in Rx.

On mathematical modeling and numerical simulation of chemical kinetics in turbulent lean premixed combustion

Energy Technology Data Exchange (ETDEWEB)

Lilleberg, Bjorn

2011-07-01

This thesis investigates turbulent reacting lean premixed flows with detailed treatment of the chemistry. First, the fundamental equations which govern laminar and turbulent reacting flows are presented. A perfectly stirred reactor numerical code is developed to investigate the role of unmixedness and chemical kinetics in driving combustion instabilities. This includes both global single-step and detailed chemical kinetic mechanisms. The single-step mechanisms predict to some degree a similar behavior as the detailed mechanisms. However, it is shown that simple mechanisms can by themselves introduce instabilities. Magnussens Eddy Dissipation Concept (EDC) for turbulent combustion is implemented in the open source CFD toolbox OpenFOAM R for treatment of both fast and detailed chemistry. RANS turbulence models account for the turbulent compressible flow. A database of pre-calculated chemical time scales, which contains the influence of chemical kinetics, is coupled to EDC with fast chemistry to account for local extinction in both diffusion and premixed flames. Results are compared to fast and detailed chemistry calculations. The inclusion of the database shows significantly better results than the fast chemistry calculations while having a comparably small computational cost. Numerical simulations of four piloted lean premixed jet flames falling into the 'well stirred reactor/broken reaction zones' regime, with strong finite-rate chemistry effects, are performed. Measured and predicted scalars compare well for the two jets with the lowest velocities. The two jets with the highest velocities experience extinction and reignition, and the simulations are able to capture the decrease and increase of the OH mass fractions, but the peak values are higher than in the experiments. Also numerical simulations of a lean premixed lifted jet flame with high sensitivity to turbulence modeling and chemical kinetics are performed. Limitations of the applied turbulence and

Closed-loop system for growth of aquatic biomass and gasification thereof

Science.gov (United States)

Oyler, James R.

2017-09-19

Processes, systems, and methods for producing combustible gas from wet biomass are provided. In one aspect, for example, a process for generating a combustible gas from a wet biomass in a closed system is provided. Such a process may include growing a wet biomass in a growth chamber, moving at least a portion of the wet biomass to a reactor, heating the portion of the wet biomass under high pressure in the reactor to gasify the wet biomass into a total gas component, separating the gasified component into a liquid component, a non-combustible gas component, and a combustible gas component, and introducing the liquid component and non-combustible gas component containing carbon dioxide into the growth chamber to stimulate new wet biomass growth.

Acid digestion and pressurization control in combustible radwaste treatment

International Nuclear Information System (INIS)

Allen, C.R.; Cowan, R.G.; Grelecki, C.J.

1978-01-01

Acid digestion has been developed to reduce the volume of combustible nuclear waste materials, while converting them to an inert, noncombustible residue. A 100 kg/day test unit has recently been constructed to process radioactively contaminated combustible wastes. The unit, called the Radioactive Acid Digestion Test Unit (RADTU) was completed in September, 1977, and is currently undergoing nonradioactive shakedown tests. Radioactive operation is expected in May, 1978. Because of uncertainties in waste composition and reactivity, the system was required to contain pressurizations. This led to the development of a simple and inexpensive system, which is capable of attenuating a shock wave from a full scale vapor detonation. The system has potential application in a wide spectrum of chemical reactors, since the fabrication materials are resistant to a very wide range of corrosive chemical attack

Pilot-scale incineration testing of an oxygen-enhanced combustion system

International Nuclear Information System (INIS)

Waterland, L.R.; Lee, J.W.; Staley, L.J.

1989-01-01

This paper discusses a series of demonstration tests of the American Combustion, Inc., Thermal Destruction System performed under the Superfund innovative technology evaluation (SITE) program. This oxygen-enhanced combustion system was retrofit to the pilot-scale rotary kiln incinerator at EPA's Combustion Research Facility. This system's performance was tested firing contaminated soil from the Stringfellow Superfund Site, both alone and mixed with a hazardous coal tar waste (decanter tank tar sludge form coking operations - K087). Comparative performance with conventional incinerator operation was tested. Test results show that compliance with the hazardous waste incinerator performance standards of 99.99 percent principal organic hazardous constituent (POHC) destruction and removal efficiency (DRE) and particulate emissions of less than 180 mg/dscm at 7 percent O 2 was achieved for all tests. The Pyretron oxygen-enhanced combustion system allowed in-compliance operation at double the mixed waste feedrate possible with conventional incineration, and with a 60 percent increase in charge weight than possible with conventional incineration

Active fault diagnosis in closed-loop uncertain systems

DEFF Research Database (Denmark)

Niemann, Hans Henrik

2006-01-01

Fault diagnosis of parametric faults in closed-loop uncertain systems by using an auxiliary input vector is considered in this paper, i.e. active fault diagnosis (AFD). The active fault diagnosis is based directly on the socalled fault signature matrix, related to the YJBK (Youla, Jabr, Bongiorno...... and Kucera) parameterization. Conditions are given for exact detection and isolation of parametric faults in closed-loop uncertain systems....

Some Factors Affecting Combustion in an Internal-Combustion Engine

Science.gov (United States)

Rothrock, A M; Cohn, Mildred

1936-01-01

An investigation of the combustion of gasoline, safety, and diesel fuels was made in the NACA combustion apparatus under conditions of temperature that permitted ignition by spark with direct fuel injection, in spite of the compression ratio of 12.7 employed. The influence of such variables as injection advance angle, jacket temperature, engine speed, and spark position was studied. The most pronounced effect was that an increase in the injection advance angle (beyond a certain minimum value) caused a decrease in the extent and rate of combustion. In almost all cases combustion improved with increased temperature. The results show that at low air temperatures the rates of combustion vary with the volatility of the fuel, but that at high temperatures this relationship does not exist and the rates depend to a greater extent on the chemical nature of the fuel.

Combustion chemistry and formation of pollutants; Chimie de la combustion et formation des polluants

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-12-31

This book of proceedings reports on 7 papers on combustion chemistry and formation of pollutants presented during the workshop organized by the `Combustion and Flames` section of the French society of thermal engineers. The chemistry of combustion is analyzed in various situations such as: turbojet engines, spark ignition engines, industrial burners, gas turbines etc... Numerical simulation is used to understand the physico-chemical processes involved in combustion, to describe the kinetics of oxidation, combustion and flame propagation, and to predict the formation of pollutants. (J.S.)

Morphology evolution and nanostructure of chemical looping transition metal oxide materials upon redox processes

International Nuclear Information System (INIS)

Qin, Lang; Cheng, Zhuo; Guo, Mengqing; Fan, Jonathan A.; Fan, Liang-Shih

2017-01-01

Transition metal are heavily used in chemical looping technologies because of their high oxygen carrying capacity and high thermal reactivity. These oxygen activities result in the oxide formation and oxygen vacancy formation that affect the nanoscale crystal phase and morphology within these materials and their subsequent bulk chemical behavior. In this study, two selected earlier transition metals manganese and cobalt as well as two selected later transition metals copper and nickel that are important to chemical looping reactions are investigated when they undergo cyclic redox reactions. We found Co microparticles exhibited increased CoO impurity presence when oxidized to Co_3O_4 upon cyclic oxidation; CuO redox cycles prefer to be limited to a reduced form of Cu_2O and an oxidized form of CuO; Mn microparticles were oxidized to a mixed phases of MnO and Mn_3O_4, which causes delamination during oxidation. For Ni microparticles, a dense surface were observed during the redox reaction. The atomistic thermodynamics methods and density functional theory (DFT) calculations are carried out to elucidate the effect of oxygen dissociation and migration on the morphological evolution of nanostructures during the redox processes. Our results indicate that the earlier transition metals (Mn and Co) tend to have stronger interaction with O_2 than the later transition metals (Ni and Cu). Also, our modified Brønsted−Evans−Polanyi (BEP) relationship for reaction energies and total reaction barriers reveals that reactions of earlier transition metals are more exergonic and have lower oxygen dissociation barriers than those of later transition metals. In addition, it was found that for these transition metal oxides the oxygen vacancy formation energies increase with the depth. The oxide in the higher oxidation state of transition metal has lower vacancy formation energy, which can facilitate forming the defective nanostructures. The fundamental understanding of these metal

Virtual velocity loop based on MEMS accelerometers for optical stabilization control system

Science.gov (United States)

Ren, Wei; Deng, Chao; Mao, Yao; Ren, Ge

2017-08-01

In the optical stabilization control system (OSCS) control system based on a charge-coupled device (CCD), stabilization performance of the line-of-sight is severely limited by the mechanical resonance and the low sampling rate of the CCD. An approach to improve the stabilization performance of the OSCS control system with load restriction based on three loops, including an acceleration loop, a virtual velocity loop, and a position loop, by using MEMS accelerometers and a CCD is proposed. The velocity signal is obtained by accelerators instead of gyro sensors. Its advantages are low power, low cost, small size, and wide measuring range. A detailed analysis is provided to show how to design the virtual velocity loop and correct virtual velocity loop drift. Experimental results show that the proposed multiloop feedback control method with virtual velocity loop in which the disturbance suppression performance is better than that of the dual loop control with only an acceleration loop and a position loop at low frequency.

Thermogravimetric Analysis Laboratory

Data.gov (United States)

Federal Laboratory Consortium — At NETL’s Thermogravimetric Analysis Laboratory in Morgantown, WV, researchers study how chemical looping combustion (CLC) can be applied to fossil energy systems....

Closed loop steam cooled airfoil

Science.gov (United States)

Widrig, Scott M.; Rudolph, Ronald J.; Wagner, Gregg P.

2006-04-18

An airfoil, a method of manufacturing an airfoil, and a system for cooling an airfoil is provided. The cooling system can be used with an airfoil located in the first stages of a combustion turbine within a combined cycle power generation plant and involves flowing closed loop steam through a pin array set within an airfoil. The airfoil can comprise a cavity having a cooling chamber bounded by an interior wall and an exterior wall so that steam can enter the cavity, pass through the pin array, and then return to the cavity to thereby cool the airfoil. The method of manufacturing an airfoil can include a type of lost wax investment casting process in which a pin array is cast into an airfoil to form a cooling chamber.

Simulation of low temperature combustion mechanism of different combustion-supporting agents in close-coupled DOC and DPF system.

Science.gov (United States)

Jiao, Penghao; Li, Zhijun; Li, Qiang; Zhang, Wen; He, Li; Wu, Yue

2018-07-01

In the coupled Diesel Oxidation Catalyst (DOC) and Diesel Particular Filter (DPF) system, soot cannot be completely removed by only using the passive regeneration. And DPF active regeneration is necessary. The research method in this paper is to spray different kinds of combustion-supporting agents to the DOC in the front of the DPF. Therefore, the low temperature combustion mechanism of different kinds of combustion-supporting agents in DOC was studied, in order to grasp the law of combustion in DOC, and the influence of follow-up emission on DPF removal of soot. During the study, CH 4 H 2 mixture and diesel (n-heptane + toluene) were used as combustion-supporting agents respectively. The simplified mechanisms of two kinds of gas mixtures used as the combustion-supporting agents in DPF have been constructed and testified in the paper. In this paper, the combustion and emission conditions of the two combustion-supporting agents were analyzed so as to meet the practical requirements of different working conditions. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

46 CFR 62.35-35 - Starting systems for internal-combustion engines.

Science.gov (United States)

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Starting systems for internal-combustion engines. 62.35-35 Section 62.35-35 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE... Starting systems for internal-combustion engines. The starting systems for propulsion engines and for prime...

Combustion systems and power plants incorporating parallel carbon dioxide capture and sweep-based membrane separation units to remove carbon dioxide from combustion gases

Science.gov (United States)

Wijmans, Johannes G [Menlo Park, CA; Merkel, Timothy C [Menlo Park, CA; Baker, Richard W [Palo Alto, CA

2011-10-11

Disclosed herein are combustion systems and power plants that incorporate sweep-based membrane separation units to remove carbon dioxide from combustion gases. In its most basic embodiment, the invention is a combustion system that includes three discrete units: a combustion unit, a carbon dioxide capture unit, and a sweep-based membrane separation unit. In a preferred embodiment, the invention is a power plant including a combustion unit, a power generation system, a carbon dioxide capture unit, and a sweep-based membrane separation unit. In both of these embodiments, the carbon dioxide capture unit and the sweep-based membrane separation unit are configured to be operated in parallel, by which we mean that each unit is adapted to receive exhaust gases from the combustion unit without such gases first passing through the other unit.

Two-loop feed water control system in BWR plants

International Nuclear Information System (INIS)

Omori, Takashi; Watanabe, Takao; Hirose, Masao.

1982-01-01

In the process of the start-up and shutdown of BWR plants, the operation of changing over feed pumps corresponding to plant output is performed. Therefore, it is necessary to develop the automatic changeover system for feed pumps, which minimizes the variation of water level in reactors and is easy to operate. The three-element control system with the water level in reactors, the flow rate of main steam and the flow rate of feed water as the input is mainly applied, but long time is required for the changeover of feed pumps. The two-loop feed control system can control simultaneously two pumps being changed over, therefore it is suitable to the automatic changeover control system for feed pumps. Also it is excellent for the control of the recirculating valves of feed pumps. The control characteristics of the two-loop feed water control system against the external disturbance which causes the variation of water level in reactors were examined. The results of analysis by simulation are reported. The features of the two-loop feed water control system, the method of simulation and the evaluation of the two-loop feed water control system are described. Its connection with a digital feed water recirculation control system is expected. (Kako, I.)

Modeling of Supersonic Combustion Systems for Sustained Hypersonic Flight

Directory of Open Access Journals (Sweden)

Stephen M. Neill

2017-11-01

Full Text Available Through Computational Fluid Dynamics and validation, an optimal scramjet combustor has been designed based on twin-strut Hydrogen injection to sustain flight at a desired speed of Mach 8. An investigation undertaken into the efficacy of supersonic combustion through various means of injection saw promising results for Hydrogen-based systems, whereby strut-style injectors were selected over transverse injectors based on their pressure recovery performance and combustive efficiency. The final configuration of twin-strut injectors provided robust combustion and a stable region of net thrust (1873 kN in the nozzle. Using fixed combustor inlet parameters and injection equivalence ratio, the finalized injection method advanced to the early stages of two-dimensional (2-D and three-dimensional (3-D scramjet engine integration. The overall investigation provided a feasible supersonic combustion system, such that Mach 8 sustained cruise could be achieved by the aircraft concept in a computational design domain.

Design of a High Intensity Turbulent Combustion System

Science.gov (United States)

2015-05-01

mixing of the reactants in chemical reactors, boilers , furnaces and mixing of fuel and air in engines take place in turbulent flow. One of the most...determining flame speed. When a tube containing combustible mixture, the flame speed is the propagation speed of the flame front towards the unburned...stress criteria is effective when the material is ductile in nature. This stress theory is developed from the 44 ’distortion energy failure theory

Prevalence of dependent loops in urinary drainage systems in hospitalized patients.

Science.gov (United States)

Danek, Gale; Gravenstein, Nikolaus; Lizdas, David E; Lampotang, Samsun

2015-01-01

The purpose of this study was to measure the prevalence and configuration of dependent loops in urinary drainage systems in hospitalized, catheterized adults. The study sample comprised 141 patients with indwelling urinary catheters; subjects were hospitalized at an academic health center in northern Florida. We measured the prevalence of dependent loops in urine drainage systems and the incidence of urine-filled dependent loops over a 3-week period. We measured the heights of the crest (H(c)), trough (H(t)), and, when urine-filled dependent loops were present, the patient-side (H(p)) and bag-side (H(b)) menisci with a laser measurement system. All variables were measured in centimeters. The majority of observed urine drainage systems (85%) contained dependent loops in the drainage tubing and 93.8% of the dependent loops contained urine. H(c) and H(t) averaged 45.1 ± 11.1 and 27 ± 16.7 cm, respectively. Meniscus height difference (H(b) - H(p)) averaged 8.2 ± 5.8 and -12.2 ± 9.9 cm when H(p) H(b) (32.7%), respectively. We found that dependent loops are extremely common in urinary drainage systems among hospitalized patients despite the manufacturer recommendations and nursing and hospital policies. Maintaining the urine drainage tubing free of dependent loops would require incorporation into nursing care priorities and workflow as inadvertent force on the tubing, for example, patient movement or nurse contact can change tubing configuration and allow excess drainage tubing to re-form a dependent loop.

Loop Transfer Matrix and Loop Quantum Mechanics

International Nuclear Information System (INIS)

Savvidy, George K.

2000-01-01

The gonihedric model of random surfaces on a 3d Euclidean lattice has equivalent representation in terms of transfer matrix K(Q i ,Q f ), which describes the propagation of loops Q. We extend the previous construction of the loop transfer matrix to the case of nonzero self-intersection coupling constant κ. We introduce the loop generalization of Fourier transformation which allows to diagonalize transfer matrices, that depend on symmetric difference of loops only and express all eigenvalues of 3d loop transfer matrix through the correlation functions of the corresponding 2d statistical system. The loop Fourier transformation allows to carry out the analogy with quantum mechanics of point particles, to introduce conjugate loop momentum P and to define loop quantum mechanics. We also consider transfer matrix on 4d lattice which describes propagation of memebranes. This transfer matrix can also be diagonalized by using the generalized Fourier transformation, and all its eigenvalues are equal to the correlation functions of the corresponding 3d statistical system. In particular the free energy of the 4d membrane system is equal to the free energy of 3d gonihedric system of loops and is equal to the free energy of 2d Ising model. (author)

Isothermal Oxidation of Magnetite to Hematite in Air and Cyclic Reduction/Oxidation Under Carbon Looping Combustion Conditions

Science.gov (United States)

Simmonds, Tegan; Hayes, Peter C.

2017-12-01

In the carbon looping combustion process the oxygen carrier is regenerated through oxidation in air; this process has been simulated by the oxidation of dense synthetic magnetite for selected temperatures and times. The oxidation of magnetite in air is shown to occur through the formation of dense hematite layers on the particle surface. This dense hematite forms through lath type shear transformations or solid-state diffusion through the product layer. Cyclic reduction in CO-CO2/oxidation in air of hematite single crystals has been carried out under controlled laboratory conditions at 1173 K (900 °C). It has been shown that the initial reduction step is critical to determining the product microstructure, which consists of gas pore dendrites in the magnetite matrix with blocky hematite formed on the pore surfaces. The progressive growth of the magnetite layer with the application of subsequent cycles appears to continue until no original hematite remains, after which physical disintegration of the particles takes place.

Experimental and CFD investigation of gas phase freeboard combustion

DEFF Research Database (Denmark)

Andersen, Jimmy

Reliable and accurate modeling capabilities for combustion systems are valuable tools for optimization of the combustion process. This work concerns primary precautions for reducing NO emissions, thereby abating the detrimental effects known as “acid rain”, and minimizing cost for flue gas...... treatment. The aim of this project is to provide validation data for Computational Fluid Dynamic (CFD) models relevant for grate firing combustion conditions. CFD modeling is a mathematical tool capable of predicting fluid flow, mixing and chemical reaction with thermal conversion and transport. Prediction......, but under well-defined conditions. Comprehensive experimental data for velocity field, temperatures, and gas composition are obtained from a 50 kW axisymmetric non-swirling natural gas fired combustion setup under two different settings. Ammonia is added to the combustion setup in order to simulate fuel...

Chemical looping reforming in packed-bed reactors : modelling, experimental validation and large-scale reactor design

NARCIS (Netherlands)

Spallina, V.; Marinello, B.; Gallucci, F.; Romano, M.C.; van Sint Annaland, M.

This paper addresses the experimental demonstration and model validation of chemical looping reforming in dynamically operated packed-bed reactors for the production of H2 or CH3OH with integrated CO2 capture. This process is a combination of auto-thermal and steam methane reforming and is carried

Review article: closed-loop systems in anesthesia: is there a potential for closed-loop fluid management and hemodynamic optimization?

Science.gov (United States)

Rinehart, Joseph; Liu, Ngai; Alexander, Brenton; Cannesson, Maxime

2012-01-01

Closed-loop (automated) controllers are encountered in all aspects of modern life in applications ranging from air-conditioning to spaceflight. Although these systems are virtually ubiquitous, they are infrequently used in anesthesiology because of the complexity of physiologic systems and the difficulty in obtaining reliable and valid feedback data from the patient. Despite these challenges, closed-loop systems are being increasingly studied and improved for medical use. Two recent developments have made fluid administration a candidate for closed-loop control. First, the further description and development of dynamic predictors of fluid responsiveness provides a strong parameter for use as a control variable to guide fluid administration. Second, rapid advances in noninvasive monitoring of cardiac output and other hemodynamic variables make goal-directed therapy applicable for a wide range of patients in a variety of clinical care settings. In this article, we review the history of closed-loop controllers in clinical care, discuss the current understanding and limitations of the dynamic predictors of fluid responsiveness, and examine how these variables might be incorporated into a closed-loop fluid administration system.

Flow and Combustion in Advanced Gas Turbine Combustors

CERN Document Server

Janicka, Johannes; Schäfer, Michael; Heeger, Christof

2013-01-01

With regard to both the environmental sustainability and operating efficiency demands, modern combustion research has to face two main objectives, the optimization of combustion efficiency and the reduction of pollutants. This book reports on the combustion research activities carried out within the Collaborative Research Center (SFB) 568 “Flow and Combustion in Future Gas Turbine Combustion Chambers” funded by the German Research Foundation (DFG). This aimed at designing a completely integrated modeling and numerical simulation of the occurring very complex, coupled and interacting physico-chemical processes, such as turbulent heat and mass transport, single or multi-phase flows phenomena, chemical reactions/combustion and radiation, able to support the development of advanced gas turbine chamber concepts.

IEA combustion agreement : a collaborative task on alternative fuels in combustion

International Nuclear Information System (INIS)

Larmi, M.

2009-01-01

The focus of the alternative fuels in combustion task of the International Energy Agency is on high efficiency engine combustion, furnace combustion, and combustion chemistry. The objectives of the task are to develop optimum combustion for dedicated fuels by fully utilizing the physical and chemical properties of synthetic and renewable fuels; a significant reduction in carbon dioxide, NOx and particulate matter emissions; determine the minimum emission levels for dedicated fuels; and meet future emission standards of engines without or with minimum after-treatment. This presentation discussed the alternative fuels task and addressed issues such as synthetic fuel properties and benefits. The anticipated future roadmap was presented along with a list of the synthetic and renewable engine fuels to be studied, such as neat oxygenates like alcohols and ethers, biogas/methane and gas combustion, fuel blends, dual fuel combustion, high cetane number diesel fuels like synthetic Fischer-Tropsch diesel fuel and hydrogenated vegetable oil, and low CN number fuels. Implementation examples were also discussed, such as fuel spray studies in optical spray bombs; combustion research in optical engines and combustion chambers; studies on reaction kinetics of combustion and emission formation; studies on fuel properties and ignition behaviour; combustion studies on research engines; combustion optimization; implementing the optimum combustion in research engines; and emission measurements. Overall milestone examples and the overall schedule of participating countries were also presented. figs.

Extended lattice Boltzmann scheme for droplet combustion.

Science.gov (United States)

Ashna, Mostafa; Rahimian, Mohammad Hassan; Fakhari, Abbas

2017-05-01

The available lattice Boltzmann (LB) models for combustion or phase change are focused on either single-phase flow combustion or two-phase flow with evaporation assuming a constant density for both liquid and gas phases. To pave the way towards simulation of spray combustion, we propose a two-phase LB method for modeling combustion of liquid fuel droplets. We develop an LB scheme to model phase change and combustion by taking into account the density variation in the gas phase and accounting for the chemical reaction based on the Cahn-Hilliard free-energy approach. Evaporation of liquid fuel is modeled by adding a source term, which is due to the divergence of the velocity field being nontrivial, in the continuity equation. The low-Mach-number approximation in the governing Navier-Stokes and energy equations is used to incorporate source terms due to heat release from chemical reactions, density variation, and nonluminous radiative heat loss. Additionally, the conservation equation for chemical species is formulated by including a source term due to chemical reaction. To validate the model, we consider the combustion of n-heptane and n-butanol droplets in stagnant air using overall single-step reactions. The diameter history and flame standoff ratio obtained from the proposed LB method are found to be in good agreement with available numerical and experimental data. The present LB scheme is believed to be a promising approach for modeling spray combustion.

Web-based ground loop supervision system for the TJ-II Stellarator

International Nuclear Information System (INIS)

Pena, A. de la; Lapayese, F.; Pacios, L.; Carrasco, R.

2005-01-01

To minimize electromagnetic interferences in diagnostic and control signals, and to guarantee safe operation of TJ-II, ground loops must be avoided. In order to meet this goal, the whole grounding system of the TJ-II was split into multiple single branches that are connected at a single earth point located near the TJ-II structure in the torus hall. A real-time ground loop supervision system (GLSS) has been designed, manufactured and tested by the TJ-II control group for detecting unintentional short circuits between isolated grounded parts. A web server running on the real-time operating system OS-9 provides remote access to the real-time ground loops measurement. Ground loops monitoring and different operation modes can be configured via any web browser. This paper gives the detailed design of the whole TJ-II ground loop supervision system and its results during its operation

Web-based ground loop supervision system for the TJ-II Stellarator

Energy Technology Data Exchange (ETDEWEB)

Pena, A. de la [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain)]. E-mail: a.delapena@ciemat.es; Lapayese, F. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain); Pacios, L. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain); Carrasco, R. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain)

2005-11-15

To minimize electromagnetic interferences in diagnostic and control signals, and to guarantee safe operation of TJ-II, ground loops must be avoided. In order to meet this goal, the whole grounding system of the TJ-II was split into multiple single branches that are connected at a single earth point located near the TJ-II structure in the torus hall. A real-time ground loop supervision system (GLSS) has been designed, manufactured and tested by the TJ-II control group for detecting unintentional short circuits between isolated grounded parts. A web server running on the real-time operating system OS-9 provides remote access to the real-time ground loops measurement. Ground loops monitoring and different operation modes can be configured via any web browser. This paper gives the detailed design of the whole TJ-II ground loop supervision system and its results during its operation.

Effect of Spray System on Fission Product Distribution in Containment During a Severe Accident in a Two-Loop Pressurized Water Reactor

Directory of Open Access Journals (Sweden)

Mehdi Dehjourian

2016-08-01

Full Text Available The containment response during the first 24 hours of a low-pressure severe accident scenario in a nuclear power plant with a two-loop Westinghouse-type pressurized water reactor was simulated with the CONTAIN 2.0 computer code. The accident considered in this study is a large-break loss-of-coolant accident, which is not successfully mitigated by the action of safety systems. The analysis includes pressure and temperature responses, as well as investigation into the influence of spray on the retention of fission products and the prevention of hydrogen combustion in the containment.

The Role of Attrition and Solids Recovery in a Chemical Looping Combustion Process Effet de l’attrition et de la récupération des particules dans le procédé de combustion en boucle chimique

Directory of Open Access Journals (Sweden)

Kramp M.

2011-05-01

Full Text Available In the present work, the steady-state behavior of a Chemical Looping Combustion process of interconnected fluidized bed reactors is simulated. The simulations have been carried out in two different scales, 50 kWth and 100 MWth. Attrition model derived from small scale laboratory experiments has been employed for the prediction of the process behavior in terms of attrition and Oxygen Carrier loss. Information on Oxygen Carrier characteristics and reaction kinetics were taken from literature. Realistic circulation mass flows of Oxygen Carrier particles are obtained and Oxygen Carrier losses are quantified. The large scale process looses significantly more Oxygen Carrier than the small scale process based on the same amount of thermal energy produced. Incomplete conversion in the air reactor could be identified as a critical point. Another issue is the fuel gas bypassing the Oxygen Carrier particles through bubbles in the large scale process which leads to lowered fuel conversions. The simulations indicate that a similar performance of a pilot scale and a large scale process is not guaranteed due to the scale-up effect on fluid dynamics. Furthermore, the simulations allow an assessment of the influence of the quality of the solids recovery system on the Oxygen Carrier loss. The distribution of the losses between possible origins is investigated and different changes in the solids recovery system are discussed regarding their potential to decrease the Oxygen Carrier loss. For example, the addition of a second-stage cyclone after the air reactor of the large scale process reduces the Oxygen Carrier loss significantly. Le présent travail propose un modèle de simulation en continu du procédé de combustion en boucle chimique constitué de deux lits fluidisés interconnectés. Les simulations ont été conduites à deux échelles 50 kWth correspondant à une installation pilote et 100 MWth correspondant à une installation industrielle. Un modèle d

LES SOFTWARE FOR THE DESIGN OF LOW EMISSION COMBUSTION SYSTEMS FOR VISION 21 PLANTS

International Nuclear Information System (INIS)

Steven Cannon; Baifang Zuo; Virgil Adumitroaie; Keith McDaniel; Clifford Smith

2002-01-01

Further development of a combustion Large Eddy Simulation (LES) code for the design of advanced gaseous combustion systems is described in this sixth quarterly report. CFD Research Corporation (CFDRC) is developing the LES module within the parallel, unstructured solver included in the commercial CFD-ACE+ software. In this quarter, in-situ adaptive tabulation (ISAT) for efficient chemical rate storage and retrieval was implemented and tested within the Linear Eddy Model (LEM). ISAT type 3 is being tested so that extrapolation can be performed and further improve the retrieval rate. Further testing of the LEM for subgrid chemistry was performed for parallel applications and for multi-step chemistry. Validation of the software on backstep and bluff-body reacting cases were performed. Initial calculations of the SimVal experiment at Georgia Tech using their LES code were performed. Georgia Tech continues the effort to parameterize the LEM over composition space so that a neural net can be used efficiently in the combustion LES code. A new and improved Artificial Neural Network (ANN), with log-transformed output, for the 1-step chemistry was implemented in CFDRC's LES code and gave reasonable results. This quarter, the 2nd consortium meeting was held at CFDRC. Next quarter, LES software development and testing will continue. Alpha testing of the code will continue to be performed on cases of interest to the industrial consortium. Optimization of subgrid models will be pursued, particularly with the ISAT approach. Also next quarter, the demonstration of the neural net approach, for multi-step chemical kinetics speed-up in CFD-ACE+, will be accomplished

Behavioral analysis of differential Hebbian learning in closed-loop systems

DEFF Research Database (Denmark)

Kulvicius, Tomas; Kolodziejski, Christoph; Tamosiunaite, Minija

2010-01-01

Understanding closed loop behavioral systems is a non-trivial problem, especially when they change during learning. Descriptions of closed loop systems in terms of information theory date back to the 1950s, however, there have been only a few attempts which take into account learning, mostly...... measuring information of inputs. In this study we analyze a specific type of closed loop system by looking at the input as well as the output space. For this, we investigate simulated agents that perform differential Hebbian learning (STDP). In the first part we show that analytical solutions can be found...

Study of mechanically activated coal combustion

Directory of Open Access Journals (Sweden)

Burdukov Anatolij P.

2009-01-01

Full Text Available Combustion and air gasification of mechanically activated micro-ground coals in the flux have been studied. Influence of mechanically activated methods at coals grinding on their chemical activeness at combustion and gasification has been determined. Intense mechanical activation of coals increases their chemical activeness that enables development of new highly boosted processing methods for coals with various levels of metamorphism.

Phase-locked loops. [in analog and digital circuits communication system

Science.gov (United States)

Gupta, S. C.

1975-01-01

An attempt to systematically outline the work done in the area of phase-locked loops which are now used in modern communication system design is presented. The analog phase-locked loops are well documented in several books but discrete, analog-digital, and digital phase-locked loop work is scattered. Apart from discussing the various analysis, design, and application aspects of phase-locked loops, a number of references are given in the bibliography.

Gradual combustion - method for nitrogen oxide suppression during brown coal combustion

Energy Technology Data Exchange (ETDEWEB)

Kotler, V.P.; Verzakov, V.N.; Lobov, T.V.

1990-10-01

Discusses combustion of brown coal in BKZ-500-140-1 boilers and factors that influence emission of nitrogen oxides. Temperature distribution in the furnace was evaluated. Effects of burner position, burner number and burner type as well as air excess ratio on chemical reactions during brown coal combustion, formation of nitrogen oxides and their emission were comparatively evaluated. Analyses showed that by optimum arrangement of burners and selecting the optimum air excess ratio a part of nitrogen oxides formed during the initial phase of combustion was reduced to molecular nitrogen in the second phase. On the basis of evaluations the following recommendations for furnace design are made: use of straight-flow burners characterized by a reduced mixing ratio with secondary air, parallel arrangement of burners which guarantees mixing of the combustion products from the burners with stable and unstable combustion (products of incomplete coal combustion), reducing the air excess ratio to below 1.0. 5 refs.

A LabVIEW model incorporating an open-loop arterial impedance and a closed-loop circulatory system.

Science.gov (United States)

Cole, R T; Lucas, C L; Cascio, W E; Johnson, T A

2005-11-01

While numerous computer models exist for the circulatory system, many are limited in scope, contain unwanted features or incorporate complex components specific to unique experimental situations. Our purpose was to develop a basic, yet multifaceted, computer model of the left heart and systemic circulation in LabVIEW having universal appeal without sacrificing crucial physiologic features. The program we developed employs Windkessel-type impedance models in several open-loop configurations and a closed-loop model coupling a lumped impedance and ventricular pressure source. The open-loop impedance models demonstrate afterload effects on arbitrary aortic pressure/flow inputs. The closed-loop model catalogs the major circulatory waveforms with changes in afterload, preload, and left heart properties. Our model provides an avenue for expanding the use of the ventricular equations through closed-loop coupling that includes a basic coronary circuit. Tested values used for the afterload components and the effects of afterload parameter changes on various waveforms are consistent with published data. We conclude that this model offers the ability to alter several circulatory factors and digitally catalog the most salient features of the pressure/flow waveforms employing a user-friendly platform. These features make the model a useful instructional tool for students as well as a simple experimental tool for cardiovascular research.

Gain Scheduling Control based on Closed-Loop System Identification

DEFF Research Database (Denmark)

Bendtsen, Jan Dimon; Trangbæk, Klaus

the first and a second operating point is identified in closed-loop using system identification methods with open-loop properties. Next, a linear controller is designed for this linearised model, and gain scheduling control can subsequently be achieved by interpolating between each controller...

A complete closed loop control system for MNSR

International Nuclear Information System (INIS)

Wang Liyu

1988-01-01

The MNSR (Miniature Neutron Source Reactor), a 27 kW reactor, was built in 1984 in the Institute of Atomic Energy, Beijing, China. A microcomputer closed-loop control system has been developed for the MNSR using an IBM PC-XT. This system not only controls the reactor, but it is also a data acquisition system and a reactivity monitor for the reactor. A closed-loop control system can be used for reactors such as the MNSR, in which the power is self-limited and the reactivity is limited to less than 5mk (∼0.7$). As a data acquisition system or a reactivity monitor, it is applicable for any nuclear reactor. This paper describes the hardware and software in detail. 4 refs, 11 figs

Internet of Things Based Combustible Ice Safety Monitoring System Framework

Science.gov (United States)

Sun, Enji

2017-05-01

As the development of human society, more energy is requires to meet the need of human daily lives. New energies play a significant role in solving the problems of serious environmental pollution and resources exhaustion in the present world. Combustible ice is essentially frozen natural gas, which can literally be lit on fire bringing a whole new meaning to fire and ice with less pollutant. This paper analysed the advantages and risks on the uses of combustible ice. By compare to other kinds of alternative energies, the advantages of the uses of combustible ice were concluded. The combustible ice basic physical characters and safety risks were analysed. The developments troubles and key utilizations of combustible ice were predicted in the end. A real-time safety monitoring system framework based on the internet of things (IOT) was built to be applied in the future mining, which provide a brand new way to monitoring the combustible ice mining safety.

Approximate Models for Closed-Loop Trajectory Tracking in Underactuated Systems

Data.gov (United States)

National Aeronautics and Space Administration — Control of robotic systems, as a field, spans both traditional closed-loop feedback techniques and modern machine learning strategies, which are primarily open-loop....

Adiabatic flame temperature of sodium combustion and sodium-water reaction

International Nuclear Information System (INIS)

Okano, Y.; Yamaguchi, A.

2001-01-01

In this paper, background information of sodium fire and sodium-water reaction accidents of LMFBR (liquid metal fast breeder reactor) is mentioned at first. Next, numerical analysis method of GENESYS is described in detail. Next, adiabatic flame temperature and composition of sodium combustion are analyzed, and affect of reactant composition, such oxygen and moisture, is discussed. Finally, adiabatic reaction zone temperature and composition of sodium-water reaction are calculated, and affects of reactant composition, sodium vaporization, and pressure are stated. Chemical equilibrium calculation program for generic chemical system (GENESYS) is developed in this study for the research on adiabatic flame temperature of sodium combustion and adiabatic reaction zone temperature of sodium-water reaction. The maximum flame temperature of the sodium combustion is 1,950 K at the standard atmospheric condition, and is not affected by the existence of moisture. The main reaction product is Na 2 O (l) , and in combustion in moist air, with NaOH (g) . The maximum reaction zone temperature of the sodium-water reaction is 1,600 K, and increases with the system pressure. The main products are NaOH (g) , NaOH (l) and H2 (g) . Sodium evaporation should be considered in the cases of sodium-rich and high pressure above 10 bar

Klystron 'efficiency loop' for the ALS storage ring RF system

International Nuclear Information System (INIS)

Kwiatkowski, Slawomir; Julian, Jim; Baptiste, Kenneth

2002-01-01

The recent energy crisis in California has led us to investigate the high power RF systems at the Advanced Light Source (ALS) in order to decrease the energy consumption and power costs. We found the Storage Ring Klystron Power Amplifier system operating as designed but with significant power waste. A simple proportional-integrator (PI) analog loop, which controls the klystron collector beam current, as a function of the output RF power, has been designed and installed. The design considerations, besides efficiency improvement, were to interface to the existing system without major expense. They were to also avoid the klystron cathode power supply filter's resonance in the loop's dynamics, and prevent a conflict with the existing Cavity RF Amplitude Loop dynamics. This efficiency loop will allow us to save up to 700 MW-hours of electrical energy per year and increase the lifetime of the klystron

Fluidised bed combustion system

International Nuclear Information System (INIS)

McKenzie, E.C.

1976-01-01

Fluidized bed combustion systems that facilitates the maintenance of the depth of the bed are described. A discharge pipe projects upwardly into the bed so that bed material can flow into its upper end and escape downwardly. The end of the pipe is surrounded by an enclosure and air is discharged into the enclosure so that material will enter the pipe from within the enclosure and have been cooled in the enclosure by the air discharged into it. The walls of the enclosure may themselves be cooled

Catalytic combustion of gasified waste - Experimental part. Final report

Energy Technology Data Exchange (ETDEWEB)

Jaeraas, Sven; Kusar, Henrik [Royal Institute of Technology, Stockholm (Sweden). Chemical Engineering and Technology

2003-08-01

This final report covers the work that has been performed within the project P 10547-2, 'Catalytic combustion of gasified waste - system analysis ORWARE'. This project is part of the research programme 'Energy from Waste' financed by the Swedish National Energy Administration. The project has been carried out at the division of Industrial Ecology and at the division of Chemical Technology at Royal Inst. of Technology. The aim of the project has been to study the potentials for catalytic combustion of gasified waste. The supposed end user of the technique is a smaller community in Sweden with 15,000-20,000 inhabitants. The project contains of two sub projects: an experimental part carried out at Chemical Technology and a system analysis carried out at Industrial Ecology. This report covers the experimental part of the project carried out at Chemical Technology. The aim for the experimental part has been to develop and test catalysts with long life-time and a high performance, to reduce the thermal-NO{sub x} below 5 ppm and to significantly reduce NO{sub x} formed from fuel-bound nitrogen. Different experimental studies have been carried out within the project: a set-up of catalytic materials have been tested over a synthetic mixture of the gasified waste, the influence of sulfur present in the gas stream, NO{sub x} formation from fuel bound nitrogen, kinetic studies of CO and H{sub 2} with and without the presence of water and the effects of adding a co-metal to palladium catalysts Furthermore a novel annular reactor design has been used to carry out experiments for kinetic measurements. Real gasification tests of waste pellets directly coupled to catalytic combustion have successfully been performed. The results obtained from the experiments, both the catalytic combustion and from the gasification, have been possible to use in the system analysis. The aim of the system analysis of catalytic combustion of gasified waste takes into consideration

Bidirectional neural interface: Closed-loop feedback control for hybrid neural systems.

Science.gov (United States)

Chou, Zane; Lim, Jeffrey; Brown, Sophie; Keller, Melissa; Bugbee, Joseph; Broccard, Frédéric D; Khraiche, Massoud L; Silva, Gabriel A; Cauwenberghs, Gert

2015-01-01

Closed-loop neural prostheses enable bidirectional communication between the biological and artificial components of a hybrid system. However, a major challenge in this field is the limited understanding of how these components, the two separate neural networks, interact with each other. In this paper, we propose an in vitro model of a closed-loop system that allows for easy experimental testing and modification of both biological and artificial network parameters. The interface closes the system loop in real time by stimulating each network based on recorded activity of the other network, within preset parameters. As a proof of concept we demonstrate that the bidirectional interface is able to establish and control network properties, such as synchrony, in a hybrid system of two neural networks more significantly more effectively than the same system without the interface or with unidirectional alternatives. This success holds promise for the application of closed-loop systems in neural prostheses, brain-machine interfaces, and drug testing.

CFD analysis of municipal solid waste combustion using detailed chemical kinetic modelling.

Science.gov (United States)

Frank, Alex; Castaldi, Marco J

2014-08-01

Nitrogen oxides (NO x ) emissions from the combustion of municipal solid waste (MSW) in waste-to-energy (WtE) facilities are receiving renewed attention to reduce their output further. While NO x emissions are currently 60% below allowed limits, further reductions will decrease the air pollution control (APC) system burden and reduce consumption of NH3. This work combines the incorporation of the GRI 3.0 mechanism as a detailed chemical kinetic model (DCKM) into a custom three-dimensional (3D) computational fluid dynamics (CFD) model fully to understand the NO x chemistry in the above-bed burnout zones. Specifically, thermal, prompt and fuel NO formation mechanisms were evaluated for the system and a parametric study was utilized to determine the effect of varying fuel nitrogen conversion intermediates between HCN, NH3 and NO directly. Simulation results indicate that the fuel nitrogen mechanism accounts for 92% of the total NO produced in the system with thermal and prompt mechanisms accounting for the remaining 8%. Results also show a 5% variation in final NO concentration between HCN and NH3 inlet conditions, demonstrating that the fuel nitrogen intermediate assumed is not significant. Furthermore, the conversion ratio of fuel nitrogen to NO was 0.33, revealing that the majority of fuel nitrogen forms N2. © The Author(s) 2014.

Analysis on reduced chemical kinetic model of N-heptane for HCCI combustion. Paper no. IGEC-1-072

International Nuclear Information System (INIS)

Yao, M.; Zheng, Z.

2005-01-01

Because of high complexity coupled with multidimensional fluid dynamics, it is difficult to apply detailed chemical kinetic model to simulate practical engines. A reduced model of n-heptane has been developed on the basic of detailed mechanism by sensitivity analysis and reaction path analysis of every stage of combustion. The new reduced mechanism consists of 35 species and 41 reactions, and it is effective in engine condition. The results show that it gives predictions similar to the detailed model in ignition timing, in-cylinder temperature and pressure. Furthermore, the reduced mechanism can be used to simulate boundary condition of partial combustion in good agreement with the detailed mechanism. (author)

Mathematical Modeling in Combustion Science

CERN Document Server

Takeno, Tadao

1988-01-01

An important new area of current research in combustion science is reviewed in the contributions to this volume. The complicated phenomena of combustion, such as chemical reactions, heat and mass transfer, and gaseous flows, have so far been studied predominantly by experiment and by phenomenological approaches. But asymptotic analysis and other recent developments are rapidly changing this situation. The contributions in this volume are devoted to mathematical modeling in three areas: high Mach number combustion, complex chemistry and physics, and flame modeling in small scale turbulent flow combustion.

Device to lower NOx in a gas turbine engine combustion system

Science.gov (United States)

Laster, Walter R; Schilp, Reinhard; Wiebe, David J

2015-02-24

An emissions control system for a gas turbine engine including a flow-directing structure (24) that delivers combustion gases (22) from a burner (32) to a turbine. The emissions control system includes: a conduit (48) configured to establish fluid communication between compressed air (22) and the combustion gases within the flow-directing structure (24). The compressed air (22) is disposed at a location upstream of a combustor head-end and exhibits an intermediate static pressure less than a static pressure of the combustion gases within the combustor (14). During operation of the gas turbine engine a pressure difference between the intermediate static pressure and a static pressure of the combustion gases within the flow-directing structure (24) is effective to generate a fluid flow through the conduit (48).

Biofuels combustion.

Science.gov (United States)

Westbrook, Charles K

2013-01-01

This review describes major features of current research in renewable fuels derived from plants and from fatty acids. Recent and ongoing fundamental studies of biofuel molecular structure, oxidation reactions, and biofuel chemical properties are reviewed, in addition to combustion applications of biofuels in the major types of engines in which biofuels are used. Biofuels and their combustion are compared with combustion features of conventional petroleum-based fuels. Two main classes of biofuels are described, those consisting of small, primarily alcohol, fuels (particularly ethanol, n-butanol, and iso-pentanol) that are used primarily to replace or supplement gasoline and those derived from fatty acids and used primarily to replace or supplement conventional diesel fuels. Research efforts on so-called second- and third-generation biofuels are discussed briefly.

Setting up experimental incineration system for low-level radioactive samples and combustion experiments

International Nuclear Information System (INIS)

Yumoto, Yasuhiro; Hanafusa, Tadashi; Nagamatsu, Tomohiro; Okada, Shigeru

1997-01-01

An incineration system was constructed which were composed of a combustion furnace (AP-150R), a cyclone dust collector, radioisotope trapping and measurement apparatus and a radioisotope storage room built in the first basement of the Radioisotope Center. Low level radioactive samples (LLRS) used for the combustion experiment were composed of combustible material or semi-combustible material containing 500 kBq of 99m TcO 4 or 23.25 kBq of 131 INa. The distribution of radioisotopes both in the inside and outside of combustion furnace were estimated. We measured radioactivity of a smoke duct gas in terminal exit of the exhaust port. In case of combustion of LLRS containing 99m TcO 4 or 131 INa, concentration of radioisotopes at the exhaust port showed less than legal concentration limit of these radioisotopes. In cases of combustion of LLRS containing 99m TcO 4 or 131 INa, decontamination factors of the incineration system were 120 and 1.1, respectively. (author)

Support system for loop device operator. Analysis of technological processes

International Nuclear Information System (INIS)

Yakovlev, V.V.; Mozhaev, A.A.; Lyadin, A.V.

1988-01-01

The paper presents the results obtained from the analysis of controlling the loops of a research reactor. A method of optimized interaction of the operator and hardware of the control system by computeraided identification of the cause of regime violation is considered. The equipment diagnostics based on use of the expert system methods and tuzzy algorithms enables to propose a support system for application in new generation of loops

Phase loop bandwidth measurements on the advanced photon source 352 MHz rf systems

International Nuclear Information System (INIS)

Horan, D.; Nassiri, A.; Schwartz, C.

1997-01-01

Phase loop bandwidth tests were performed on the Advanced Photon Source storage ring 352-MHz rf systems. These measurements were made using the HP3563A Control Systems Analyzer, with the rf systems running at 30 kilowatts into each of the storage ring cavities, without stored beam. An electronic phase shifter was used to inject approximately 14 degrees of stimulated phase shift into the low-level rf system, which produced measureable response voltage in the feedback loops without upsetting normal rf system operation. With the PID (proportional-integral-differential) amplifier settings at the values used during accelerator operation, the measurement data revealed that the 3-dB response for the cavity sum and klystron power-phase loops is approximately 7 kHz and 45 kHz, respectively, with the cavities the primary bandwidth-limiting factor in the cavity-sum loop. Data were taken at various PID settings until the loops became unstable. Crosstalk between the two phase loops was measured

A review of control strategies in closed-loop neuroprosthetic systems

Directory of Open Access Journals (Sweden)

James Wright

2016-07-01

Full Text Available It has been widely recognized that closed-loop neuroprosthetic systems achieve more favorable outcomes for users then equivalent open-loop devices. Improved performance of tasks, better usability and greater embodiment have all been reported in systems utilizing some form of feedback. However the interdisciplinary work on neuroprosthetic systems can lead to miscommunication due to similarities in well established nomenclature in different fields. Here we present a review of control strategies in existing experimental, investigational and clinical neuroprosthetic systems in order to establish a baseline and promote a common understanding of different feedback modes and closed-loop controllers. The first section provides a brief discussion of feedback control and control theory. The second section reviews the control strategies of recent Brain Machine Interfaces, neuromodulatory implants, neuroprosthetic systems and assistive neurorobotic devices. The final section examines the different approaches to feedback in current neuroprosthetic and neurorobotic systems.

Groundwater recharge through wells in open loop geothermal system: problems and solutions - part 1

Directory of Open Access Journals (Sweden)

Giovanni Pietro Beretta

2017-07-01

Full Text Available In the two parts of this article, the problems related to the management of water wells as part of a low-enthalpy geothermal power plant by means of heat pumps (open loop system are described. In many cases, in absence of discharge in surface water and/or to ensure the conservation of the resource from a quantitative point of view, a doublet system constituted by a pumping and a recharge well is provided. The clogging phenomenon often occurs in this kind of plant, affecting wells with different functions and different thermal potential related to water withdrawal and reinjection into the ground. This phenomenon is due to the presence of air bubbles, suspended solids, bacterial growth and to the chemical-physical reactions that are described in the text. Besides acknowledging the activities for recharge wells management to avoid the fracturing of the drain and the cementation, is also suggested the procedure of in situ tests that are used to properly determine the optimal well discharge, which determines the efficiency and effectiveness of the geothermal system and its economic performance.It is finally shown a regional regulation on the water quality used in an open loop.

Amine-based post-combustion CO2 capture in air-blown IGCC systems with cold and hot gas clean-up

International Nuclear Information System (INIS)

Giuffrida, A.; Bonalumi, D.; Lozza, G.

2013-01-01

Highlights: • Hot fuel gas clean-up is a very favorable technology for IGCC concepts. • IGCC net efficiency reduces to 41.5% when realizing post-combustion CO 2 capture. • Complex IGCC layouts are necessary if exhaust gas recirculation is realized. • IGCC performance does not significantly vary with exhaust gas recirculation. - Abstract: This paper focuses on the thermodynamic performance of air-blown IGCC systems with post-combustion CO 2 capture by chemical absorption. Two IGCC technologies are investigated in order to evaluate two different strategies of coal-derived gas clean-up. After outlining the layouts of two power plants, the first with conventional cold gas clean-up and the second with hot gas clean-up, attention is paid to the CO 2 capture station and to issues related to exhaust gas recirculation in combined cycles. The results highlight that significant improvements in IGCC performance are possible if hot coal-derived gas clean-up is realized before the syngas fuels the combustion turbine, so the energy cost of CO 2 removal in an amine-based post-combustion mode is less strong. In particular, IGCC net efficiency as high as 41.5% is calculated, showing an interesting potential if compared to the one of IGCC systems with pre-combustion CO 2 capture. Thermodynamic effects of exhaust gas recirculation are investigated as well, even though IGCC performance does not significantly vary against a more complicated plant layout

Development of Novel Fe-Based Coating Systems for Internal Combustion Engines

Science.gov (United States)

Bobzin, K.; Öte, M.; Königstein, T.; Dröder, K.; Hoffmeister, H.-W.; Mahlfeld, G.; Schläfer, T.

2018-04-01

Nowadays, combustion engines are the most common way to power vehicles. Thereby, losses occur due to cooling, exhaust gas and friction. With regard to frictional losses, highest potentials for optimization can be found in the tribological system of the inner surface of combustion chamber and piston ring. Besides friction, corrosive stress increases, e.g., due to utilization of exhaust gas recovery. In order to save energy, reduce emissions and enhance the life span of combustion engines, the demand for innovative coating material systems, especially for the inner surface of combustion chamber, increases. This study focuses on the development of innovative iron-based coating materials for the combustion chamber. As a first step, the plasma transferred wire arc and rotating single wire arc (RSW) technologies were compared using 0.8% C-steel as a reference. Subsequently, RSW was used for coating deposition using an innovative iron-based feedstock material. In order to improve wear and corrosion resistance, boron and chromium were added to the feedstock material. After deposition, different honing topographies were manufactured and compared under tribological load. Furthermore, electrochemical corrosion tests were conducted using an electrolyte simulating the exhaust gas concentrate. Especially with regard to corrosion, the novel coating system FeCrBMn showed promising results.

Development of Novel Fe-Based Coating Systems for Internal Combustion Engines

Science.gov (United States)

Bobzin, K.; Öte, M.; Königstein, T.; Dröder, K.; Hoffmeister, H.-W.; Mahlfeld, G.; Schläfer, T.

2018-02-01

Nowadays, combustion engines are the most common way to power vehicles. Thereby, losses occur due to cooling, exhaust gas and friction. With regard to frictional losses, highest potentials for optimization can be found in the tribological system of the inner surface of combustion chamber and piston ring. Besides friction, corrosive stress increases, e.g., due to utilization of exhaust gas recovery. In order to save energy, reduce emissions and enhance the life span of combustion engines, the demand for innovative coating material systems, especially for the inner surface of combustion chamber, increases. This study focuses on the development of innovative iron-based coating materials for the combustion chamber. As a first step, the plasma transferred wire arc and rotating single wire arc (RSW) technologies were compared using 0.8% C-steel as a reference. Subsequently, RSW was used for coating deposition using an innovative iron-based feedstock material. In order to improve wear and corrosion resistance, boron and chromium were added to the feedstock material. After deposition, different honing topographies were manufactured and compared under tribological load. Furthermore, electrochemical corrosion tests were conducted using an electrolyte simulating the exhaust gas concentrate. Especially with regard to corrosion, the novel coating system FeCrBMn showed promising results.

Syngas Generation from Methane Using a Chemical-Looping Concept: A Review of Oxygen Carriers

Directory of Open Access Journals (Sweden)

Kongzhai Li

2013-01-01

Full Text Available Conversion of methane to syngas using a chemical-looping concept is a novel method for syngas generation. This process is based on the transfer of gaseous oxygen source to fuel (e.g., methane by means of a cycling process using solid oxides as oxygen carriers to avoid direct contact between fuel and gaseous oxygen. Syngas is produced through the gas-solid reaction between methane and solid oxides (oxygen carriers, and then the reduced oxygen carriers can be regenerated by a gaseous oxidant, such as air or water. The oxygen carrier is recycled between the two steps, and the syngas with a ratio of H2/CO = 2.0 can be obtained successively. Air is used instead of pure oxygen allowing considerable cost savings, and the separation of fuel from the gaseous oxidant avoids the risk of explosion and the dilution of product gas with nitrogen. The design and elaboration of suitable oxygen carriers is a key issue to optimize this method. As one of the most interesting oxygen storage materials, ceria-based and perovskite oxides were paid much attention for this process. This paper briefly introduced the recent research progresses on the oxygen carriers used in the chemical-looping selective oxidation of methane (CLSOM to syngas.

Aspects chimiques de la combustion du charbon pulvérisé. Première partie Chemical Aspects of the Combustion of Pulverized Coal. Part One

Directory of Open Access Journals (Sweden)

De Soete G. G.

2006-11-01

deux mécanismes totalement différents, par exemple entre le mécanisme d'ignition homogène et le mécanisme d'ignition hétérogène du charbon, avec des conséquences pratiques pour la stabilisation de la flamme industrielle ; autre exemple : la compétition entre les divers mécanismes homogènes de formation d'oxydes d'azote et les mécanismes hétérogènes de leur réduction sur des particules solides de coke, de suie et de cendre. Avec ces idées présentes comme un leitmotiv implicite, on passe en revue les grandes étapes de la flamme industrielle de charbon pulvérisé : la dévolatilisation rapide avec la formation progressive de volatils gazeux, de goudrons et de coke ; la transformation partielle des produits gazeux et liquides de pyrolyse en suies ainsi que leur oxydation en phase gazeuse ; la combustion hétérogène du coke ; l'ignition du charbon et sa dépendance par rapport à des processus critiques homogènes et (ou hétérogènes. Comme exemple typique d'un épiphénomènechimique, on suit la transformation des espèces azotées en NO et en N2, qui se greffe en contrepoint et à chaque pas sur tes différents thèmes successifs de cette symphonie de l'oxydation du charbon. En de nombreux points de cette évolution du charbon à travers la flamme, les connaissances de la chimie de com-bustion en phase gazeuse constituent un instrument utile d'interprétation (par exemple : pour l'oxydation des volatils, pour la discussion des modalités d'ignition. II n'en reste pas moins vrai que la plupart des problèmes chimiques hétérogènes sont bien spécifiques de la flamme de charbon ; leur traitement est rendu ardu à cause de la complexité, évolutive au cours de la combustion, du combustible solide lui-même. It is not easy to obtain a full picture of the multiple chemical phenomena which occur inside a pulverized coal flame. This bibliographie review attempts to give more than just a juxtaposition of data from the recent literature and risks making

Coal Direct Chemical Looping Retrofit to Pulverized Coal Power Plants for In-Situ CO2 Capture

Energy Technology Data Exchange (ETDEWEB)

Zeng, Liang; Li, Fanxing; Kim, Ray; Bayham, Samuel; McGiveron, Omar; Tong, Andrew; Connell, Daniel; Luo, Siwei; Sridhar, Deepak; Wang, Fei; Sun, Zhenchao; Fan, Liang-Shih

2013-09-30

A novel Coal Direct Chemical Looping (CDCL) system is proposed to effectively capture CO2 from existing PC power plants. The work during the past three years has led to an oxygen carrier particle with satisfactory performance. Moreover, successful laboratory, bench scale, and integrated demonstrations have been performed. The proposed project further advanced the novel CDCL technology to sub-pilot scale (25 kWth). To be more specific, the following objectives attained in the proposed project are: 1. to further improve the oxygen carrying capacity as well as the sulfur/ash tolerance of the current (working) particle; 2. to demonstrate continuous CDCL operations in an integrated mode with > 99% coal (bituminous, subbituminous, and lignite) conversion as well as the production of high temperature exhaust gas stream that is suitable for steam generation in existing PC boilers; 3. to identify, via demonstrations, the fate of sulfur and NOx; 4. to conduct thorough techno-economic analysis that validates the technical and economical attractiveness of the CDCL system. The objectives outlined above were achieved through collaborative efforts among all the participants. CONSOL Energy Inc. performed the techno-economic analysis of the CDCL process. Shell/CRI was able to perform feasibility and economic studies on the large scale particle synthesis and provide composite particles for the sub-pilot scale testing. The experience of B&W (with boilers) and Air Products (with handling gases) assisted the retrofit system design as well as the demonstration unit operations. The experience gained from the sub-pilot scale demonstration of the Syngas Chemical Looping (SCL) process at OSU was able to ensure the successful handling of the solids. Phase 1 focused on studies to improve the current particle to better suit the CDCL operations. The optimum operating conditions for the reducer reactor such as the temperature, char gasification enhancer type, and flow rate were identified. The

Development of a high-pressure compaction system for non-combustible solid waste

International Nuclear Information System (INIS)

Yogo, S.; Hata, T.; Torita, K.; Yamamoto, K.; Karita, Y.

1989-01-01

In recent years, nuclear power plants in Japan have been in search of a means to reduce the volume of non-combustible solid wastes and therefore the application of a high-pressure compaction system has been in demand. Most non-combustible solid wastes have been packed in 200-litre drums for storage and the situation requires a high-pressure compaction system designed exclusively for 200-litre drums. The authors have developed a high-pressure compaction system which compresses 200-litre drums filled with non-combustible solid wastes and packs them into new woo-litre drums efficiently. This paper reports the outline of this high-pressure compaction system and the results of the full-scale verification tests

User's manual of BISHOP. A Bi-Phase, Sodium-Hydrogen-Oxygen system, chemical equilibrium calculation program

International Nuclear Information System (INIS)

Okano, Yasushi; Yamaguchi, Akira

2001-07-01

In an event of sodium leakage in liquid metal fast breeder reactors, liquid sodium flows out of piping, and droplet combustion might occur under a certain environmental condition. The combustion heat and reaction products should be evaluated in the sodium fire analysis codes for investigating the influence of the sodium leak age and fire incident. In order to analyze the reaction heat and products, the multi-phase chemical equilibrium calculation program for a sodium, oxygen and hydrogen system has been developed. The developed numerical program is named BISHOP, which denotes 'Bi-Phase, Sodium-Hydrogen-Oxygen, Chemical Equilibrium Calculation Program'. The Gibbs free energy minimization method is used because of the following advantages. Chemical species are easily added and changed. A variety of thermodynamic states, such as isothermal and isentropic changes, can be dealt with in addition to constant temperature and pressure processes. In applying the free energy minimization method to solve the multi-phase sodium reaction system, three new numerical calculation techniques are developed. One is theoretical simplification of phase description in equation system, the other is to extend the Gibbs free energy minimization method to a multi-phase system, and the last is to establish the efficient search for the minimum value. The reaction heat and products at the equilibrium state can be evaluated from the initial conditions, such as temperature, pressure and reactants, using BISHOP. This report describes the thermochemical basis of chemical equilibrium calculations, the system of equations, simplification models, and the procedure to prepare input data and usage of BISHOP. (author)

Method for storing radioactive combustible waste

Science.gov (United States)

Godbee, H.W.; Lovelace, R.C.

1973-10-01

A method is described for preventing pressure buildup in sealed containers which contain radioactively contaminated combustible waste material by adding an oxide getter material to the container so as to chemically bind sorbed water and combustion product gases. (Official Gazette)

Modelling of Combustion and Pollutant Formation in a Large, Two-Stroke Marine Diesel Engine using Integrated CFD-Skeletal Chemical Mechanism

DEFF Research Database (Denmark)

Pang, Kar Mun; Karvounis, Nikolas; Schramm, Jesper

In this reported work, simulation studies of in-cylinder diesel combustion and pollutant formation processesin a two-stroke, low-speed uniflow-scavenged marine diesel engine are presented. Numerical computation is performed by integrating chemical kinetics into CFD computations. In order...... to minimize the computational runtime, an in-house skeletal n-heptane chemical mechanism is coupled with the CFD model. This surrogate fuel model comprises 89 reactions with 32 species essential to diesel ignition/combustion processes as well as the formation of soot precursors and nitrogen monoxide (NO......). Prior to the marine engine simulation,coupling of the newly developed surrogate fuel model and a revised multi-step soot model [1] is validated on the basis of optical diagnostics measurement obtained at varying ambient pressure levels [2]. It is demonstrated that the variation of ignition delay times...

[Study on expert system of infrared spectral characteristic of combustible smoke agent].

Science.gov (United States)

Song, Dong-ming; Guan, Hua; Hou, Wei; Pan, Gong-pei

2009-05-01

The present paper studied the application of expert system in prediction of infrared spectral characteristic of combustible anti-infrared smoke agent. The construction of the expert system was founded, based on the theory of minimum free energy and infrared spectral addition. After the direction of smoke agent was input, the expert system could figure out the final combustion products. Then infrared spectrogram of smoke could also be simulated by adding the spectra of all of the combustion products. Meanwhile, the screening index of smoke was provided in the wave bands of 3-5 im and 8-14 microm. FTIR spectroscope was used to investigate the performance of one kind of HC smoke. The combustion products calculated by the expert system were coincident with the actual data, and the simulant infrared spectrum was also similar to the real one of the smoke. The screening index given by the system was consistent with the known facts. It was showed that a new approach was offered for the fast discrimination of varieties of directions of smoke agent.

Increased combustion stability in modulating biomass boilers for district heating systems

Energy Technology Data Exchange (ETDEWEB)

Eriksson, Gunnar; Hermansson, Roger (eds.) [Lulea Univ. of Technology (Sweden)

2002-09-01

One of the problems in small district heating systems is the large load variation that must be handled by the system. If the boiler is designed to cover the needs during the coldest day in winter time in northern Europe it would have to run at loads as low as 10% of full load during summer time, when heat is needed only for tap water production. Load variations in small networks are quite fast and earlier investigations have shown that existing biomass boilers give rise to large amounts of harmful emissions at fast load variations and at low loads. The problem has been addressed in different ways: Three new boiler concepts have been realized and tested: A prototype of a 500 kW boiler with partitioned primary combustion chamber and supplied with a water heat store. A 10 kW bench scale combustor and a 500 kW prototype boiler based on pulsating combustion. Bench scale boilers to test the influence from applied sound on emissions and a 150 kW prototype boiler with a two-stage secondary vortex combustion chamber. Development of control and regulating equipment: Glow Guard, a control system using infra-red sensors to detect glowing char on the grate, has been constructed and tested. A fast prediction model that can be used in control systems has been developed. Simulation of the combustion process: Code to simulate pyrolysis/gasification of fuel on the grate has been developed. Combustion of the gas phase inside the combustion chamber has been simulated. The two models have been combined to describe the combustion process inside the primary chamber of a prototype boiler. A fast simulation code based on statistical methods that can predict the environmental performance of boilers has been developed. One of the boiler concepts matches the desired load span from 10 to 100% of full load with emissions far below the set limits for CO and THC and close to the set limits for NO{sub x}. The other boilers had a bit more narrow load range, one with very low emissions except for NO

SLSF loop handling system. Volume I. Structural analysis

International Nuclear Information System (INIS)

Ahmed, H.; Cowie, A.; Ma, D.

1978-10-01

SLSF loop handling system was analyzed for deadweight and postulated dynamic loading conditions, identified in Chapters II and III in Volume I of this report, using a linear elastic static equivalent method of stress analysis. Stress analysis of the loop handling machine is presented in Volume I of this report. Chapter VII in Volume I of this report is a contribution by EG and G Co., who performed the work under ANL supervision

Closed-Loop and Robust Control of Quantum Systems

Directory of Open Access Journals (Sweden)

Chunlin Chen

2013-01-01

Full Text Available For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA, and reinforcement learning (RL methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H∞ control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention.

Closed-loop and robust control of quantum systems.

Science.gov (United States)

Chen, Chunlin; Wang, Lin-Cheng; Wang, Yuanlong

2013-01-01

For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control) have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA), and reinforcement learning (RL) methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H(∞) control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention.

Closed loop two-echelon repairable item systems

NARCIS (Netherlands)

Spanjers, L.; van Ommeren, Jan C.W.; Zijm, Willem H.M.

In this paper we consider closed loop two-echelon repairable item systems with repair facilities both at a number of local service centers (called bases) and at a central location (the depot). The goal of the system is to maintain a number of production facilities (one at each base) in optimal

Closed-loop two-echelon repairable item systems

NARCIS (Netherlands)

Spanjers, L.; Zijm, Willem H.M.; van Ommeren, Jan C.W.

2003-01-01

In this paper we consider closed loop two-echelon repairable item systems with repair facilities both at a number of local service centers (called bases) and at a central location (the depot). The goal of the system is to maintain a number of production facilities (one at each base) in optimal

Closed loop two-echelon repairable item systems

NARCIS (Netherlands)

Spanjers, L.; van Ommeren, Jan C.W.; Zijm, Willem H.M.; Liberopoulos, G.; Papadopoulos, C.T.; Tan, B.; MacGregor Smith, J.; Gershwin, S.B.

2006-01-01

In this paper we consider closed loop two-echelon epairable item systems with repair facilities both at a number of local service centers (called bases) and at a central location (the depot). The goal of the system is to maintain a number of production facilities (one at each base) in optimal

Studies in combustion dynamics

Energy Technology Data Exchange (ETDEWEB)

Koszykowski, M.L. [Sandia National Laboratories, Livermore, CA (United States)

1993-12-01

The goal of this program is to develop a fundamental understanding and a quantitative predictive capability in combustion modeling. A large part of the understanding of the chemistry of combustion processes comes from {open_quotes}chemical kinetic modeling.{close_quotes} However, successful modeling is not an isolated activity. It necessarily involves the integration of methods and results from several diverse disciplines and activities including theoretical chemistry, elementary reaction kinetics, fluid mechanics and computational science. Recently the authors have developed and utilized new tools for parallel processing to implement the first numerical model of a turbulent diffusion flame including a {open_quotes}full{close_quotes} chemical mechanism.

Process/Engineering Co-Simulation of Oxy-Combustion and Chemical Looping Combustion

Energy Technology Data Exchange (ETDEWEB)

Sloan, David [Alstom Power Inc., Windsor, CT (United States)

2013-03-01

Over the past several years, the DOE has sponsored various funded programs, collectively referred to as Advanced Process Engineering Co-Simulator (APECS) programs, which have targeted the development of a steady-state simulator for advanced power plants. The simulator allows the DOE and its contractors to systematically evaluate various power plant concepts, either for preliminary conceptual design or detailed final design.

Numerical research of heat and mass transfer at the ignition of system “fabric – combustible liquid – oxidant” by the local energy source

Directory of Open Access Journals (Sweden)

Glushkov Dmitrii O.

2015-01-01

Full Text Available A numerical research was executed for macroscopic regularities determination of heat and mass transfer processes under the conditions of phase transformation and chemical reaction at the ignition of vapour coming from fabrics impregnated by typical combustible liquid into oxidant area at the local power supply. Limit conditions of heterogeneous system “fabric – combustible liquid – oxidant” ignition at the heating of single metal particle was established. Dependences of ignition delay time on temperature and rates of local power source were obtained.

Miniaturization limitations of rotary internal combustion engines

International Nuclear Information System (INIS)

Wang, Wei; Zuo, Zhengxing; Liu, Jinxiang

2016-01-01

Highlights: • Developed a phenomenological model for rotary internal combustion engines. • Presented scaling laws for the performance of micro rotary engines. • Adiabatic walls can improve the cycle efficiency but result in higher charge leakage. • A lower compression ratio can increase the efficiency due to lower mass losses. • Presented possible minimum engine size of rotary internal combustion engines. - Abstract: With the rapid development of micro electro-mechanical devices, the demands for micro power generation systems have significantly increased in recent years. Traditional chemical batteries have energy densities much lower than hydrocarbon fuels, which makes internal-combustion-engine an attractive technological alternative to batteries. Micro rotary internal combustion engine has drawn great attractions due to its planar design, which is well-suited for fabrication in MEMS. In this paper, a phenomenological model considering heat transfer and mass leakage has been developed to investigate effects of engine speed, compression ratio, blow-by and heat transfer on the performance of micro rotary engine, which provide the guidelines for preliminary design of rotary engine. The lower possible miniaturization limits of rotary combustion engines are proposed.

Transformations of inorganic coal constituents in combustion systems. Volume 1, sections 1--5: Final report

Energy Technology Data Exchange (ETDEWEB)

Helble, J.J. [ed.; Srinivasachar, S.; Wilemski, G.; Boni, A.A. [PSI Technology Co., Andover, MA (United States); Kang, Shin-Gyoo; Sarofim, A.F.; Graham, K.A.; Beer, J.M. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Peterson, T.W.; Wendt, J.O.L.; Gallagher, N.B.; Bool, L. [Arizona Univ., Tucson, AZ (United States); Huggins, F.E.; Huffman, G.P.; Shah, N.; Shah, A. [Kentucky Univ., Lexington, KY (United States)

1992-11-01

The inorganic constituents or ash contained in pulverized coal significantly increase the environmental and economic costs of coal utilization. For example, ash particles produced during combustion may deposit on heat transfer surfaces, decreasing heat transfer rates and increasing maintenance costs. The minimization of particulate emissions often requires the installation of cleanup devices such as electrostatic precipitators, also adding to the expense of coal utilization. Despite these costly problems, a comprehensive assessment of the ash formation and had never been attempted. At the start of this program, it was hypothesized that ash deposition and ash particle emissions both depended upon the size and chemical composition of individual ash particles. Questions such as: What determines the size of individual ash particles? What determines their composition? Whether or not particles deposit? How combustion conditions, including reactor size, affect these processes? remained to be answered. In this 6-year multidisciplinary study, these issues were addressed in detail. The ambitious overall goal was the development of a comprehensive model to predict the size and chemical composition distributions of ash produced during pulverized coal combustion. Results are described.

Open and Closed Loop Parametric System Identification in Compact Disk Players

DEFF Research Database (Denmark)

Vidal, Enrique Sanchez; Stoustrup, Jakob; Andersen, Palle

2001-01-01

By measuring the current through the coil of the actuators in the optical pick-up in a compact disk player, open loop parametric system identification can be performed. The parameters are identified by minimizing the least-squares loss function of the ARX model. The only parameter which cannot be...... be identified in open loop is the optical gain. This is therefore estimated in closed loop. Practical results are analyzed and show very accurate estimates of the real parameters.......By measuring the current through the coil of the actuators in the optical pick-up in a compact disk player, open loop parametric system identification can be performed. The parameters are identified by minimizing the least-squares loss function of the ARX model. The only parameter which cannot...

Chemical process control using Mat lab

International Nuclear Information System (INIS)

Kang, Sin Chun; Kim, Raeh Yeon; Kim, Yang Su; Oh, Min; Yeo, Yeong Gu; Jung, Yeon Su

2001-07-01

This book is about chemical process control, which includes the basis of process control with conception, function, composition of system and summary, change of laplace and linearization, modeling of chemical process, transfer function and block diagram, the first dynamic property of process, the second dynamic property of process, the dynamic property of combined process, control structure of feedback on component of control system, the dynamic property of feedback control loop, stability of closed loop control structure, expression of process, modification and composition of controller, analysis of vibration response and adjustment controller using vibration response.

Availability analysis of nuclear power plant system with the consideration of logical loop structures

International Nuclear Information System (INIS)

Matsuoka, Takeshi

2013-01-01

Nuclear power plants have logical loop structures in their system configuration. The typical example is a power source system, that is, a nuclear plant generates electricity and it is used for the operation of pumps in the plant. For the reliability or availability analysis of nuclear power plants, it is necessary to treat accurately logical loop structures. Authors have proposed an exact method for solving logical loop structure in reliability analysis, and generalized method has recently been presented. A nuclear power plant system is taken up and essential parts of logical loop structures are modeled into relatively simple form. The procedure to solve a loop structure is shown in which the proposed generalized method is applied, and availability of the system with loop structure is accurately solved. The analysis results indicate that reconsideration of present plant operating procedure should be made for the increase of safety of nuclear power plant in case of 'Loss of offsite power' incident. The analysis results also show an important role of loop structures for maintaining the overall system availability. The analysis procedure is also useful in effectively designing high reliable systems. (author)

Combustion modeling in advanced gas turbine systems

Energy Technology Data Exchange (ETDEWEB)

Smoot, L.D.; Hedman, P.O.; Fletcher, T.H. [Brigham Young Univ., Provo, UT (United States)] [and others

1995-10-01

The goal of the U.S. Department of Energy`s Advanced Turbine Systems (ATS) program is to help develop and commercialize ultra-high efficiency, environmentally superior, and cost competitive gas turbine systems for base-load applications in the utility, independent power producer, and industrial markets. Combustion modeling, including emission characteristics, has been identified as a needed, high-priority technology by key professionals in the gas turbine industry.

Design aspects of commercial open-loop heat pump systems

Energy Technology Data Exchange (ETDEWEB)

Rafferty, Kevin

2000-01-01

Open loop (or groundwater heat pump systems are the oldest of the ground-source systems. Common design variations include direct (groundwater used directly in the heat pump units), indirect (building loop isolated with a plate heat exchanger), and standing column (water produced and returned to the same well). Direct systems are typically limited to the smallest applications. Standing column systems are employed in hard rock geology sites where it is not possible to produce sufficient water for a conventional system. Due to its greater potential application, this paper reviews key design aspects of the indirect approach. The general design procedure is reviewed, identification of optimum groundwater flow, heat exchanger selection guidelines, well pump control, disposal options, well spacing, piping connections and related issues.

Design Aspects of Commerical Open-Loop Heat Pump Systems

Energy Technology Data Exchange (ETDEWEB)

Rafferty, Kevin

2001-03-01

Open loop (or groundwater heat pump systems are the oldest of the ground-source systems. Common design variations include direct (groundwater used directly in the heat pump units), indirect (building loop isolated with a plate heat exchanger), and standing column (water produced and returned to the same well). Direct systems are typically limited to the smallest applications. Standing column systems are employed in hard rock geology sites where it is not possible to produce sufficient water for a conventional system. Due to its greater potential application, this paper reviews key design aspects of the indirect approach. The general design procedure is reviewed, identification of optimum groundwater flow, heat exchanger selection guidelines, well pump control, disposal options, well spacing, piping connections and related issues.

Mechanistic studies of chemical looping desulfurization of Mn-based oxides using in situ X-ray absorption spectroscopy

International Nuclear Information System (INIS)

König, C.F.J.; Nachtegaal, M.; Seemann, M.; Clemens, F.; Garderen, N. van; Biollaz, S.M.A.; Schildhauer, T.J.

2014-01-01

Highlights: • Mn sorbents remove H 2 S from hot syngas in chemical looping desulfurization process. • State of Mn followed by in situ X-ray absorption spectroscopy and mass spectrometry. • Two-step mechanism explains the formation of SO 2 under reducing conditions. - Abstract: Cleaning of producer gas from biomass gasification is required for further processing, e.g. to avoid catalyst poisoning in subsequent conversion steps. High-temperature gas cleaning, of which sulfur removal is an important part, is a promising way to improve the overall efficiency of biomass conversion. In a high temperature “chemical looping desulfurization” process, a sorbent material, here manganese oxide, is cycled between producer gas from the gasifier to remove sulfur species, and an oxidizing atmosphere, in which the sulfur species are released as SO 2 . Alternatively, the use of such material as reactive bed material could be integrated into an allothermal dual fluidized bed gasifier. In a laboratory reactor, we subjected manganese-based materials to a periodically changing gas atmosphere, simulating a “chemical looping desulfurization” reactor. The “fuel reactor” gas contained H 2 , CO, CH 4 and H 2 S, similar as in the producer gas, and the “oxidizing reactor” contained diluted O 2 . Mass spectrometry showed that most of the H 2 S is taken up by the sample in the “fuel reactor” part, while also some unwanted SO 2 is generated in the “fuel reactor” part. Most of the sulfur is released in the oxidizing reactor. Simultaneous in situ X-ray absorption spectroscopy (XAS) of the Mn materials during different stages of the chemical looping desulfurization process showed that the initial Mn 3 O 4 is transformed in the presence of H 2 S to MnS via a MnO intermediate in the fuel reactor. Oxygen from the reduction of Mn 3 O 4 oxidizes some H 2 S to the undesired SO 2 in the fuel reactor. Upon exposure to O 2 , MnS is again oxidized to Mn 3 O 4 via MnO, releasing SO

Water chemistry of the JMTR IASCC irradiation loop system

International Nuclear Information System (INIS)

Hanawa, Satoshi; Oogiyanagi, Jin; Mori, Yuichiro; Saito, Junichi; Tsukada, Takashi

2006-01-01

Irradiation assisted stress corrosion cracking (IASCC) is recognized as an important degradation issue of the core-internal material for aged Boiling Water Reactors (BWRs). Therefore, irradiation loop system has been developed and installed in the Japan Materials Testing Reactor to perform the IASCC irradiation test. In the IASCC irradiation test, water chemistry of irradiation field is one of the most important key parameters because it affects initiation and propagation of cracks. This paper summarizes the measurement and evaluation method of water chemistry of IASCC irradiation loop system. (author)

Detection and control of combustion instability based on the concept of dynamical system theory

Science.gov (United States)

Gotoda, Hiroshi; Shinoda, Yuta; Kobayashi, Masaki; Okuno, Yuta; Tachibana, Shigeru

2014-02-01

We propose an online method of detecting combustion instability based on the concept of dynamical system theory, including the characterization of the dynamic behavior of combustion instability. As an important case study relevant to combustion instability encountered in fundamental and practical combustion systems, we deal with the combustion dynamics close to lean blowout (LBO) in a premixed gas-turbine model combustor. The relatively regular pressure fluctuations generated by thermoacoustic oscillations transit to low-dimensional intermittent chaos owing to the intermittent appearance of burst with decreasing equivalence ratio. The translation error, which is characterized by quantifying the degree of parallelism of trajectories in the phase space, can be used as a control variable to prevent LBO.

Detection and control of combustion instability based on the concept of dynamical system theory.

Science.gov (United States)

Gotoda, Hiroshi; Shinoda, Yuta; Kobayashi, Masaki; Okuno, Yuta; Tachibana, Shigeru

2014-02-01

We propose an online method of detecting combustion instability based on the concept of dynamical system theory, including the characterization of the dynamic behavior of combustion instability. As an important case study relevant to combustion instability encountered in fundamental and practical combustion systems, we deal with the combustion dynamics close to lean blowout (LBO) in a premixed gas-turbine model combustor. The relatively regular pressure fluctuations generated by thermoacoustic oscillations transit to low-dimensional intermittent chaos owing to the intermittent appearance of burst with decreasing equivalence ratio. The translation error, which is characterized by quantifying the degree of parallelism of trajectories in the phase space, can be used as a control variable to prevent LBO.

Measures for a quality combustion (combustion chamber exit and downstream); Mesures pour une combustion de qualite (sortie de chambre de combustion et en aval)

Energy Technology Data Exchange (ETDEWEB)

Epinat, G. [APAVE Lyonnaise, 69 (France)

1996-12-31

After a review of the different pollutants related to the various types of stationary and mobile combustion processes (stoichiometric, reducing and oxidizing combustion), measures and analyses than may be used to ensure the quality and efficiency of combustion processes are reviewed: opacimeters, UV analyzers, etc. The regulation and control equipment for combustion systems are then listed, according to the generator capacity level

Modeling and simulating combustion and generation of NOx

International Nuclear Information System (INIS)

Lazaroiu, Gheorghe

2007-01-01

This paper deals with the modeling and simulation of combustion processes and generation of NO x in a combustion chamber and boiler, with supplementary combustion in a gas turbine installation. The fuel burned in the combustion chamber was rich gas with a chemical composition more complex than natural gas. Pitcoal was used in the regenerative boiler. From the resulting combustion products, 17 compounds were retained, including nitrogen and sulphur compounds. Using the developed model, the simulation resulted in excess air for a temperature imposed at the combustion chamber exhaust. These simulations made it possible to determine the concentrations of combustion compounds with a variation in excess combustion. (author)

The Role of Chemical Processes in the Transition to Sustainable Energy Systems

Energy Technology Data Exchange (ETDEWEB)

Stucki, S.; Palumbo, R.; Baltensperger, U.; Boulouchos, K.; Haas, O.; Scherer, G.G.; Siegwolf, R.; Wokaun, A

2002-01-01

Chemical science and engineering play a central role in improving the eco- efficiency of energy services, be it by optimizing fossil fuel utilization from the source to the sinks, be it by exploring new ways of replacing fossil fuels with renewable ones. Catalytic fuel processing is required for providing clean and easy to convert inputs from contaminated and/or high molecular weight primary resources into efficient energy conversion systems such as advanced combustion engines and fuel cells. The switch from conventional fossil fuel resources to renewables such as solar or biomass requires new approaches in chemical engineering. Efficiency vs. emissions trade-offs for improving the eco-performance of combustion engines need to be optimized with improved understanding of the complex chemistry taking place in flames. New materials for fuel cells and batteries provide a means of making these devices applicable, thereby drastically cutting down on emissions from energy systems. Chemistry is not only involved in fuel processing and conversion, but it is also important at the end of the pipe, i.e. in catalytic emission control devices, in the treatment of hazardous residues from the incineration of waste materials, and in the complex interactions of air pollutants with the biosphere. (author)

Combustion pressure-based engine management system

Energy Technology Data Exchange (ETDEWEB)

Mueller, R.; Hart, M. [DaimlerChrysler, Stuttart (Germany); Truscott, A.; Noble, A. [Ricardo, Shoreham-by-Sea (United Kingdom); Kroetz, G.; Richter, C. [DaimlerChrysler, Munchen (Germany); Cavalloni, C. [Kistler Instruments AG, Winterthur (Switzerland)

2000-07-01

In order to fulfill future emissions and OBD regulations, whilst meeting increasing demands for driveability and refinement, new technologies for SI engines have to be found in terms of sensors and algorithms for engine control units. One promising way, explored in the AENEAS collaborative project between DaimlerChrysler, Kistler, Ricardo and the European Commission, is to optimize the behavior of the system by using in-cylinder measurements and analysing them with modern control algorithms. In this paper a new engine management system based on combustion pressure sensing is presented. The pressure sensor is designed to give a reliable and accurate signal of the full pressure trace during a working cycle. With the application of new technologies low cost manufacturing appears to be achievable, so that an application in mass production can be considered. Furthermore, model-based algorithms were developed to allow optimal control of the engine based on the in-cylinder measurements. The algorithms incorporate physical principles to improve efficiency, emissions and to reduce the parameterisation effort. In the paper, applications of the combustion pressure signal for air mass estimation, knock detection, ignition control cam phase detection and diagnosis are discussed. (author)

Sensor-integrated polymer actuators for closed-loop drug delivery system

Science.gov (United States)

Xu, Han; Wang, Chunlei; Kulinsky, Lawrence; Zoval, Jim; Madou, Marc

2006-03-01

This work presents manufacturing and testing of a closed-loop drug delivery system where drug release is achieved by an electrochemical actuation of an array of polymeric valves on a set of drug reservoirs. The valves are based on bi-layer structures made of polypyrrole/gold in the shape of a flap that is hinged on one side of a valve seat. Drugs stored in the underlying chambers are released by bending the bi-layer flaps back with a small applied bias. These polymeric valves simultaneously function as both drug release components and biological/chemical sensors responding to a specific biological or environmental stimulus. The sensors may send signals to the control module to realize closed-loop control of the drug release. In this study a glucose sensor has been integrated with the polymeric actuators through immobilization of glucose oxidase(GOx) within polypyrrole(PPy) valves. Sensitivities per unit area of the integrated glucose sensor have been measured and compared before and after the actuation of the sensor/actuator PPy/DBS/GOx film. Other sensing parameters such as linear range and response time were discussed as well. Using an array of these sensor/actuator cells, the amount of released drug, e.g. insulin, can be precisely controlled according to the surrounding glucose concentration detected by the glucose sensor. Activation of these reservoirs can be triggered either by the signal from the sensor, or by the signal from the operator. This approach also serves as the initial step to use the proposed system as an implantable drug delivery platform in the future.

Gaussian process regression based optimal design of combustion systems using flame images

International Nuclear Information System (INIS)

Chen, Junghui; Chan, Lester Lik Teck; Cheng, Yi-Cheng

2013-01-01

Highlights: • The digital color images of flames are applied to combustion design. • The combustion with modeling stochastic nature is developed using GP. • GP based uncertainty design is made and evaluated through a real combustion system. - Abstract: With the advanced methods of digital image processing and optical sensing, it is possible to have continuous imaging carried out on-line in combustion processes. In this paper, a method that extracts characteristics from the flame images is presented to immediately predict the outlet content of the flue gas. First, from the large number of flame image data, principal component analysis is used to discover the principal components or combinational variables, which describe the important trends and variations in the operation data. Then stochastic modeling of the combustion process is done by a Gaussian process with the aim to capture the stochastic nature of the flame associated with the oxygen content. The designed oxygen combustion content considers the uncertainty presented in the combustion. A reference image can be designed for the actual combustion process to provide an easy and straightforward maintenance of the combustion process

Fuzzy logic control and optimization system

Science.gov (United States)

Lou, Xinsheng [West Hartford, CT

2012-04-17

A control system (300) for optimizing a power plant includes a chemical loop having an input for receiving an input signal (369) and an output for outputting an output signal (367), and a hierarchical fuzzy control system (400) operably connected to the chemical loop. The hierarchical fuzzy control system (400) includes a plurality of fuzzy controllers (330). The hierarchical fuzzy control system (400) receives the output signal (367), optimizes the input signal (369) based on the received output signal (367), and outputs an optimized input signal (369) to the input of the chemical loop to control a process of the chemical loop in an optimized manner.

A closed-loop model of the respiratory system: focus on hypercapnia and active expiration.

Directory of Open Access Journals (Sweden)

Yaroslav I Molkov

Full Text Available Breathing is a vital process providing the exchange of gases between the lungs and atmosphere. During quiet breathing, pumping air from the lungs is mostly performed by contraction of the diaphragm during inspiration, and muscle contraction during expiration does not play a significant role in ventilation. In contrast, during intense exercise or severe hypercapnia forced or active expiration occurs in which the abdominal "expiratory" muscles become actively involved in breathing. The mechanisms of this transition remain unknown. To study these mechanisms, we developed a computational model of the closed-loop respiratory system that describes the brainstem respiratory network controlling the pulmonary subsystem representing lung biomechanics and gas (O2 and CO2 exchange and transport. The lung subsystem provides two types of feedback to the neural subsystem: a mechanical one from pulmonary stretch receptors and a chemical one from central chemoreceptors. The neural component of the model simulates the respiratory network that includes several interacting respiratory neuron types within the Bötzinger and pre-Bötzinger complexes, as well as the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG representing the central chemoreception module targeted by chemical feedback. The RTN/pFRG compartment contains an independent neural generator that is activated at an increased CO2 level and controls the abdominal motor output. The lung volume is controlled by two pumps, a major one driven by the diaphragm and an additional one activated by abdominal muscles and involved in active expiration. The model represents the first attempt to model the transition from quiet breathing to breathing with active expiration. The model suggests that the closed-loop respiratory control system switches to active expiration via a quantal acceleration of expiratory activity, when increases in breathing rate and phrenic amplitude no longer provide sufficient

Design and experimental investigation of an oxy-fuel combustion system for magnetohydrodynamic power extraction

Science.gov (United States)

Hernandez, Manuel Johannes

A general consensus in the scientific and research community is the need to restrict carbon emissions in energy systems. Therefore, extensive research efforts are underway to develop the next generation of energy systems. In the field of power generation, researchers are actively investigating novel methods to produce electricity in a cleaner, efficient form. Recently, Oxy-Combustion for magnetohydrodynamic power extraction has generated significant interest, since the idea was proposed as a method for clean power generation in coal and natural gas power plants. Oxy-combustion technologies have been proposed to provide high enthalpy, electrically conductive flows for direct conversion of electricity. Direct power extraction via magnetohydrodynamics (MHD) can occur as a consequence of the motion of "seeded" combustion products in the presence of magnetic fields. However, oxy-combustion technologies for MHD power extraction has not been demonstrated in the available literature. Furthermore, there are still fundamental unexplored questions remaining, associated with this technology, for MHD power extraction. In this present study, previous magnetohydrodynamic combustion technologies and technical issues in this field were assessed to develop a new combustion system for electrically conductive flows. The research aims were to fully understand the current-state-of-the-art of open-cycle magnetohydrodynamic technologies and present new future directions and concepts. The design criteria, methodology, and technical specifications of an advanced cooled oxy-combustion technology are presented in this dissertation. The design was based on a combined analytical, empirical, and numerical approach. Analytical one-dimensional (1D) design tools initiated design construction. Design variants were analyzed and vetted against performance criteria through the application of computational fluid dynamics modeling. CFD-generated flow fields permitted insightful visualization of the

Combustion Research Laboratory

Data.gov (United States)

Federal Laboratory Consortium — The Combustion Research Laboratory facilitates the development of new combustion systems or improves the operation of existing systems to meet the Army's mission for...

Operation of a cascade air conditioning system with two-phase loop

Science.gov (United States)

Feng, Yinshan; Wang, Jinliang; Zhao, Futao; Verma, Parmesh; Radcliff, Thomas D.

2018-05-29

A method of operating a heat transfer system includes starting operation of a first heat transfer fluid vapor/compression circulation loop including a fluid pumping mechanism, a heat exchanger for rejecting thermal energy from a first heat transfer fluid, and a heat absorption side of an internal heat exchanger. A first conduit in a closed fluid circulation loop circulates the first heat transfer fluid therethrough. Operation of a second two-phase heat transfer fluid circulation loop is started after starting operation of the first heat transfer fluid circulation loop. The second heat transfer fluid circulation loop transfers heat to the first heat transfer fluid circulation loop through the internal heat exchanger and includes a heat rejection side of the internal heat exchanger, a liquid pump, and a heat exchanger evaporator. A second conduit in a closed fluid circulation loop circulates a second heat transfer fluid therethrough.

Parametric analysis of a dual loop Organic Rankine Cycle (ORC) system for engine waste heat recovery

International Nuclear Information System (INIS)

Song, Jian; Gu, Chun-wei

2015-01-01

Highlights: • A dual loop ORC system is designed for engine waste heat recovery. • The two loops are coupled via a shared heat exchanger. • The influence of the HT loop condensation parameters on the LT loop is evaluated. • Pinch point locations determine the thermal parameters of the LT loop. - Abstract: This paper presents a dual loop Organic Rankine Cycle (ORC) system consisting of a high temperature (HT) loop and a low temperature (LT) loop for engine waste heat recovery. The HT loop recovers the waste heat of the engine exhaust gas, and the LT loop recovers that of the jacket cooling water in addition to the residual heat of the HT loop. The two loops are coupled via a shared heat exchanger, which means that the condenser of the HT loop is the evaporator of the LT loop as well. Cyclohexane, benzene and toluene are selected as the working fluids of the HT loop. Different condensation temperatures of the HT loop are set to maintain the condensation pressure slightly higher than the atmosphere pressure. R123, R236fa and R245fa are chosen for the LT loop. Parametric analysis is conducted to evaluate the influence of the HT loop condensation temperature and the residual heat load on the LT loop. The simulation results reveal that under different condensation conditions of the HT loop, the pinch point of the LT loop appears at different locations, resulting in different evaporation temperatures and other thermal parameters. With cyclohexane for the HT loop and R245fa for the LT loop, the maximum net power output of the dual loop ORC system reaches 111.2 kW. Since the original power output of the engine is 996 kW, the additional power generated by the dual loop ORC system can increase the engine power by 11.2%.

Analysis of beam feedback loops of RF acceleration system at TARN II

International Nuclear Information System (INIS)

Katayama, Takeshi.

1992-08-01

Two beam-feedback-loops are prepared for the frequency control of RF acceleration system at cooler-synchrotron TARN II. One is the phase-loop and the other the radial-position-loop. In the present paper, the effects of these loops on the beam dynamics in the synchrotron are studied on the basis of Laplace transformation approach as well as the numerical values for the synchrotron acceleration at TARN II. (author)

Modeling JP-8 Fuel Effects on Diesel Combustion Systems

National Research Council Canada - National Science Library

Schihl, Peter; Hoogterp, Laura; Pangilinan, Harold; Schwarz, Ernest; Bryzik, Walter

2006-01-01

.... Since engine manufacturers rely solely on DF-2 for commercial vehicle applications most domestic industry, university, and national laboratory lead diesel engine combustion system research activities...

Innovative Waste Management in the Mercury Loop of the EURISOL Multi-MW Converter Target

CERN Document Server

PSI: Jörg Neuhausen, Dorothea Schumann, Rugard Dressler, Susanne Horn, Sabrina Lüthi, Stephan Heinitz, Suresh ChirikiCERN: Thierry Stora, Martin Eller

The choice of mercury as target material imposes various questions concerning the safe operation of such a system that are related to the physical and chemical properties of the target material itself and the nuclear reaction products produced within the target during its life time of several decades. Therefore, a subtask was created within the EURISOL-DS project that is concerned with studying an innovative waste management for the generated radioactivity by chemical means. Such a study strongly depends on the radioactive inventory and its distribution throughout the target and loop system. Radioactive inventory calculations were performed within task 5 [6]. The distribution of nuclear reaction products and their chemical state that can be expected within the target and loop system is one of the topics covered in this report. Based on the results obtained by theoretical studies as well as laboratory scale experiments, the feasibility of waste reduction using chemical methods, both conventional (e.g. leaching...

Towards the use of Structural Loop Analysis to Study System Behaviour of Socio-Ecological Systems.

Science.gov (United States)

Abram, Joseph; Dyke, James

2016-04-01

Maintaining socio-ecological systems in desirable states is key to developing a growing economy, alleviating poverty and achieving a sustainable future. While the driving forces of an environmental system are often well known, the dynamics impacting these drivers can be hidden within a tangled structure of causal chains and feedback loops. A lack of understanding of a system's dynamic structure and its influence on a system's behaviour can cause unforeseen side-effects during model scenario testing and policy implementation. Structural Loop analysis of socio-ecological system models identifies dominant feedback structures during times of behavioural shift, allowing the user to monitor key influential drivers during model simulation. This work carries out Loop Eigenvalue Elasticity Analysis (LEEA) on three system dynamic models, exploring tipping points in lake systems undergoing eutrophication. The purpose is to explore the potential benefits and limitations of the technique in the field of socio-ecology. The LEEA technique shows promise for socio-ecological systems which undergo regime shifts or express oscillatory trends, but shows limited usefulness with large models. The results of this work highlight changes in feedback loop dominance, years prior to eutrophic tipping events in lake systems. LEEA could be used as an early warning signal to impending system changes, complementary to other known early warning signals. This approach could improve our understanding during critical times of a system's behaviour, changing how we approach model analysis and the way scenario testing and policy implementation are addressed in socio-ecological system models.

Exploring the Use of Design of Experiments in Industrial Processes Operating Under Closed-Loop Control

DEFF Research Database (Denmark)

Capaci, Francesca; Kulahci, Murat; Vanhatalo, Erik

2017-01-01

Industrial manufacturing processes often operate under closed-loop control, where automation aims to keep important process variables at their set-points. In process industries such as pulp, paper, chemical and steel plants, it is often hard to find production processes operating in open loop....... Instead, closed-loop control systems will actively attempt to minimize the impact of process disturbances. However, we argue that an implicit assumption in most experimental investigations is that the studied system is open loop, allowing the experimental factors to freely affect the important system...... responses. This scenario is typically not found in process industries. The purpose of this article is therefore to explore issues of experimental design and analysis in processes operating under closed-loop control and to illustrate how Design of Experiments can help in improving and optimizing...

Chemical looping fluidized-bed concentrating solar power system and method

Science.gov (United States)

Ma, Zhiwen

2017-07-11

A concentrated solar power (CSP) plant comprises a receiver configured to contain a chemical substance for a chemical reaction and an array of heliostats. Each heliostat is configured to direct sunlight toward the receiver. The receiver is configured to transfer thermal energy from the sunlight to the chemical substance in a reduction reaction. The CSP plant further comprises a first storage container configured to store solid state particles produced by the reduction reaction and a heat exchanger configured to combine the solid state particles and gas through an oxidation reaction. The heat exchanger is configured to transfer heat produced in the oxidation reaction to a working fluid to heat the working fluid. The CSP plant further comprises a power turbine coupled to the heat exchanger, such that the heated working fluid turns the power turbine, and a generator coupled to and driven by the power turbine to generate electricity.

Study of solving a Toda dynamic system with loop algebra

International Nuclear Information System (INIS)

Zhu Qiao; Yang Zhanying; Shi Kangjie; Wen Junqing

2006-01-01

The authors construct a Toda system with Loop algebra, and prove that the Lax equation L=[L,M] can be solved by means of solving a regular Riemann-Hilbert problem. In our system, M in Lax pair is an antisymmetrical matrix, while L=L + + M, and L + is a quasi-upper triangular matrix of loop algebra. In order to check our result, the authors exactly solve an R-H problem under a given initial condition as an example. (authors)

System and method for reducing combustion dynamics in a combustor

Science.gov (United States)

Uhm, Jong Ho; Johnson, Thomas Edward; Zuo, Baifang; York, William David

2013-08-20

A system for reducing combustion dynamics in a combustor includes an end cap having an upstream surface axially separated from a downstream surface, and tube bundles extend through the end cap. A diluent supply in fluid communication with the end cap provides diluent flow to the end cap. Diluent distributors circumferentially arranged inside at least one tube bundle extend downstream from the downstream surface and provide fluid communication for the diluent flow through the end cap. A method for reducing combustion dynamics in a combustor includes flowing fuel through tube bundles that extend axially through an end cap, flowing a diluent through diluent distributors into a combustion chamber, wherein the diluent distributors are circumferentially arranged inside at least one tube bundle and each diluent distributor extends downstream from the end cap, and forming a diluent barrier in the combustion chamber between at least one pair of adjacent tube bundles.

Methane combustion over lanthanum-based perovskite mixed oxides

Energy Technology Data Exchange (ETDEWEB)

Arandiyan, Hamidreza [New South Wales Univ., Sydney (Australia). School of Chemical Engineering

2015-11-01

This book presents current research into the catalytic combustion of methane using perovskite-type oxides (ABO{sub 3}). Catalytic combustion has been developed as a method of promoting efficient combustion with minimum pollutant formation as compared to conventional catalytic combustion. Recent theoretical and experimental studies have recommended that noble metals supported on (ABO{sub 3}) with well-ordered porous networks show promising redox properties. Three-dimensionally ordered macroporous (3DOM) materials with interpenetrated and regular mesoporous systems have recently triggered enormous research activity due to their high surface areas, large pore volumes, uniform pore sizes, low cost, environmental benignity, and good chemical stability. These are all highly relevant in terms of the utilization of natural gas in light of recent catalytic innovations and technological advances. The book is of interest to all researchers active in utilization of natural gas with novel catalysts. The research covered comes from the most important industries and research centers in the field. The book serves not only as a text for researcher into catalytic combustion of methane, 3DOM perovskite mixed oxide, but also explores the field of green technologies by experts in academia and industry. This book will appeal to those interested in research on the environmental impact of combustion, materials and catalysis.

Estimation of Model Uncertainties in Closed-loop Systems

DEFF Research Database (Denmark)

Niemann, Hans Henrik; Poulsen, Niels Kjølstad

2008-01-01

This paper describe a method for estimation of parameters or uncertainties in closed-loop systems. The method is based on an application of the dual YJBK (after Youla, Jabr, Bongiorno and Kucera) parameterization of all systems stabilized by a given controller. The dual YJBK transfer function...

CATALYTIC COMBUSTION OF METHANE OVER Pt/γ-Al2O3 IN MICRO-COMBUSTOR WITH DETAILED CHEMICAL KINETIC MECHANISMS

Directory of Open Access Journals (Sweden)

JUNJIE CHEN

2014-11-01

Full Text Available Micro-scale catalytic combustion characteristics and heat transfer processes of preheated methane-air mixtures (φ = 0.4 in the plane channel were investigated numerically with detailed chemical kinetic mechanisms. The plane channel of length L = 10.0 mm, height H =1.0 mm and wall thickness δ = 0.1 mm, which inner horizontal surfaces contained Pt/γ-Al2O3 catalyst washcoat. The computational results indicate that the presence of the gas phase reactions extends mildly the micro-combustion stability limits at low and moderate inlet velocities due to the strong flames establishment, and have a more profound effect on extending the high-velocity blowout limits by allowing for additional heat release originating mainly from the incomplete CH4 gas phase oxidation in the plane channel. When the same mass flow rate (ρin × Vin is considered, the micro-combustion stability limits at p: 0.1 MPa are much narrower than at p: 0.6 MPa due to both gas phase and catalytic reaction activities decline with decreasing pressure. Catalytic micro-combustor can achieve stable combustion at low solid thermal conductivity ks < 0.1 W∙m-1•K-1, while the micro-combustion extinction limits reach their larger extent for the higher thermal conductivity ks = 20.0-100.0 W∙m-1•K-1. The existence of surface radiation heat transfers significantly effects on the micro-combustion stability limits and micro-combustors energy balance. Finally, gas phase combustion in catalytic micro-combustors can be sustained at the sub-millimeter scale (plane channel height of 0.25 mm.

Investigation of combustion and thermodynamic performance of a lean burn catalytic combustion gas turbine system

International Nuclear Information System (INIS)

Yin Juan; Weng Yiwu

2011-01-01

The goals of this research were to investigate the combustion and thermodynamic performance of a lean burn catalytic combustion gas turbine. The characteristics of lean burn catalytic combustion were investigated by utilising 1D heterogeneous plug flow model which was validated by experiments. The effects of operating parameters on catalytic combustion were numerically analysed. The system models were built in ASPEN Plus and three independent design variables, i.e. compressor pressure ratio (PR), regenerator effectiveness (RE) and turbine inlet temperature (TIT) were selected to analyse the thermodynamic performance of the thermal cycle. The main results show that: simulations from 1D heterogeneous plug flow model can capture the trend of catalytic combustion and describe the behavior of the catalytic monolith in detail. Inlet temperature is the most significant parameter that impacts operation of the catalytic combustor. When TIT and RE are constant, the increase of PR results in lowering the inlet temperature of the catalytic combustor, which results in decreasing methane conversion. The peak thermal efficiency and the optimal PR at a constant TIT increase with the increase of TIT; and at the constant PR, the thermal efficiency increases with the increase of TIT. However, with lower TIT conditions, the optimal PR and the peak efficiency at a constant TIT of the LBCCGT cycle are relative low to that of the conventional cycle. When TIT and PR are constant, the decrease of RE may result in lower methane conversion. The influences of RE on the methane conversion and the thermal efficiency are more significant at higher PRs. The higher thermal efficiency for the lower RE is achieved at lower PR.

One-loop renormalization of a gravity-scalar system

Energy Technology Data Exchange (ETDEWEB)

Park, I.Y. [Philander Smith College, Department of Applied Mathematics, Little Rock, AR (United States)

2017-05-15

Extending the renormalizability proposal of the physical sector of 4D Einstein gravity, we have recently proposed renormalizability of the 3D physical sector of gravity-matter systems. The main goal of the present work is to conduct systematic one-loop renormalization of a gravity-matter system by applying our foliation-based quantization scheme. In this work we explicitly carry out renormalization of a gravity-scalar system with a Higgs-type potential. With the fluctuation part of the scalar field gauged away, the system becomes renormalizable through a metric field redefinition. We use dimensional regularization throughout. One of the salient aspects of our analysis is how the graviton propagator acquires the ''mass'' term. One-loop calculations lead to renormalization of the cosmological and Newton constants. We discuss other implications of our results as well: time-varying vacuum energy density and masses of the elementary particles as well as the potential relevance of Neumann boundary condition for black hole information. (orig.)

One-loop renormalization of a gravity-scalar system

International Nuclear Information System (INIS)

Park, I.Y.

2017-01-01

Extending the renormalizability proposal of the physical sector of 4D Einstein gravity, we have recently proposed renormalizability of the 3D physical sector of gravity-matter systems. The main goal of the present work is to conduct systematic one-loop renormalization of a gravity-matter system by applying our foliation-based quantization scheme. In this work we explicitly carry out renormalization of a gravity-scalar system with a Higgs-type potential. With the fluctuation part of the scalar field gauged away, the system becomes renormalizable through a metric field redefinition. We use dimensional regularization throughout. One of the salient aspects of our analysis is how the graviton propagator acquires the ''mass'' term. One-loop calculations lead to renormalization of the cosmological and Newton constants. We discuss other implications of our results as well: time-varying vacuum energy density and masses of the elementary particles as well as the potential relevance of Neumann boundary condition for black hole information. (orig.)

One-loop renormalization of a gravity-scalar system

Science.gov (United States)

Park, I. Y.

2017-05-01

Extending the renormalizability proposal of the physical sector of 4D Einstein gravity, we have recently proposed renormalizability of the 3D physical sector of gravity-matter systems. The main goal of the present work is to conduct systematic one-loop renormalization of a gravity-matter system by applying our foliation-based quantization scheme. In this work we explicitly carry out renormalization of a gravity-scalar system with a Higgs-type potential. With the fluctuation part of the scalar field gauged away, the system becomes renormalizable through a metric field redefinition. We use dimensional regularization throughout. One of the salient aspects of our analysis is how the graviton propagator acquires the "mass" term. One-loop calculations lead to renormalization of the cosmological and Newton constants. We discuss other implications of our results as well: time-varying vacuum energy density and masses of the elementary particles as well as the potential relevance of Neumann boundary condition for black hole information.

Experimental kinetic parameters in the thermo-fluid-dynamic modelling of coal combustion

International Nuclear Information System (INIS)

Migliavacca, G.; Perini, M.; Parodi, E.

2001-01-01

The designing and the optimisation of modern and efficient combustion systems are nowadays frequently based on calculation tools for mathematical modelling, which are able to predict the evolution of the process starting from the first principles of physics. Otherwise, in many cases, specific experimental parameters are needed to describe the specific nature of the materials considered in the calculations. It is especially true in the modelling of coal combustion, which is a complex process strongly dependent on the chemical and physical features of the fuel. This paper describes some experimental techniques used to estimate the fundamental kinetic parameters of coal combustion and shows how this data may be introduced in a model calculation to predict the pollutant emissions from a real scale combustion plant [it

Molten salt combustion of radioactive wastes

International Nuclear Information System (INIS)

Grantham, L.F.; McKenzie, D.E.; Richards, W.L.; Oldenkamp, R.D.

1976-01-01

The Atomics International Molten Salt Combustion Process reduces the weight and volume of combustible β-γ contaminated transuranic waste by utilizing air in a molten salt medium to combust organic materials, to trap particulates, and to react chemically with any acidic gases produced during combustion. Typically, incomplete combustion products such as hydrocarbons and carbon monoxide are below detection limits (i.e., 3 ) is directly related to the sodium chloride vapor pressure of the melt; >80% of the particulate is sodium chloride. Essentially all metal oxides (combustion ash) are retained in the melt, e.g., >99.9% of the plutonium, >99.6% of the europium, and >99.9% of the ruthenium are retained in the melt. Both bench-scale radioactive and pilot scale (50 kg/hr) nonradioactive combustion tests have been completed with essentially the same results. Design of three combustors for industrial applications are underway

Cyclic combustion driven shocks in a sompressible vortex as a source of MHD power

Energy Technology Data Exchange (ETDEWEB)

Jenkins, J. M.; Swithenbank, J.

1963-04-15

Theory and experimental data are presented on the properties of cyclic, combustion-driven shocks in a compressible vortex. In this system, part of the chemical energy is converted directly into kinetic energy. Because the temperatures encountered in these combustions approach those obtained in detonations, it is suggested that the cycliccombustion system might be suitable for the production of magnetohydrodynamic power. The experimental data presented are based on observations of rocket motor characteristics. Effects of instabilities are discussed. (T.F.H.)

Gasdynamic modeling and parametric study of mesoscale internal combustion swing engine/generator systems

Science.gov (United States)

Gu, Yongxian

The demand of portable power generation systems for both domestic and military applications has driven the advances of mesoscale internal combustion engine systems. This dissertation was devoted to the gasdynamic modeling and parametric study of the mesoscale internal combustion swing engine/generator systems. First, the system-level thermodynamic modeling for the swing engine/generator systems has been developed. The system performance as well as the potentials of both two- and four-stroke swing engine systems has been investigated based on this model. Then through parameterc studies, the parameters that have significant impacts on the system performance have been identified, among which, the burn time and spark advance time are the critical factors related to combustion process. It is found that the shorter burn time leads to higher system efficiency and power output and the optimal spark advance time is about half of the burn time. Secondly, the turbulent combustion modeling based on levelset method (G-equation) has been implemented into the commercial software FLUENT. Thereafter, the turbulent flame propagation in a generic mesoscale combustion chamber and realistic swing engine chambers has been studied. It is found that, in mesoscale combustion engines, the burn time is dominated by the mean turbulent kinetic energy in the chamber. It is also shown that in a generic mesoscale combustion chamber, the burn time depends on the longest distance between the initial ignition kernel to its walls and by changing the ignition and injection locations, the burn time can be reduced by a factor of two. Furthermore, the studies of turbulent flame propagation in real swing engine chambers show that the combustion can be enhanced through in-chamber turbulence augmentation and with higher engine frequency, the burn time is shorter, which indicates that the in-chamber turbulence can be induced by the motion of moving components as well as the intake gas jet flow. The burn time

Waste gas combustion in a Hanford radioactive waste tank

International Nuclear Information System (INIS)

Travis, J.R.; Fujita, R.K.; Spore, J.W.

1994-01-01

It has been observed that a high-level radioactive waste tank generates quantities of hydrogen, ammonia, nitrous oxide, and nitrogen that are potentially well within flammability limits. These gases are produced from chemical and nuclear decay reactions in a slurry of radioactive waste materials. Significant amounts of combustible and reactant gases accumulate in the waste over a 110- to 120-d period. The slurry becomes Taylor unstable owing to the buoyancy of the gases trapped in a matrix of sodium nitrate and nitrite salts. As the contents of the tank roll over, the generated waste gases rupture through the waste material surface, allowing the gases to be transported and mixed with air in the cover-gas space in the dome of the tank. An ignition source is postulated in the dome space where the waste gases combust in the presence of air resulting in pressure and temperature loadings on the double-walled waste tank. This analysis is conducted with hydrogen mixing studies HMS, a three-dimensional, time-dependent fluid dynamics code coupled with finite-rate chemical kinetics. The waste tank has a ventilation system designed to maintain a slight negative gage pressure during normal operation. We modeled the ventilation system with the transient reactor analysis code (TRAC), and we coupled these two best-estimate accident analysis computer codes to model the ventilation system response to pressures and temperatures generated by the hydrogen and ammonia combustion

Estimation of Parametric Fault in Closed-loop Systems

DEFF Research Database (Denmark)

Niemann, Hans Henrik; Poulsen, Niels Kjølstad

2015-01-01

The aim of this paper is to present a method for estimation of parametric faults in closed-loop systems. The key technology applied in this paper is coprime factorization of both the dynamic system as well as the feedback controller. Using the Youla-Jabr-Bongiorno-Kucera (YJBK) parameterization...

Ash quality and environmental quality assurance system in co-combustion - Co-combustion of forest industry waste

International Nuclear Information System (INIS)

Laine-Ylijoki, J.; Wahlstroem, M.

2000-01-01

The environmental acceptability and possible utilization of co-combustion ashes will have a significant influence on the wider use of co-combustion in the future. At present the correlation between currently used fuels, their mixture ratios, and quality variations in ashes are not known, which complicates the assessment of possible utilization and environmental acceptability of co-combustion ashes. The composition of ashes has also been found to vary significantly. Effective utilization requires that process variations to alter ash composition and quality variations are known in advance. The aim of the research was to characterize the fly ash from co- combustion of peat, wood and biological paper mill sludge produced under different fuel loadings, especially with and without sludge addition, ant to identify critical parameters influencing on the ash composition. The variations in the leaching properties of ashes collected daily were followed up. The environmental acceptability of the ashes produced under different fuel loadings, especially their suitability for use in road constructions, were evaluated. The project included also the preparation of laboratory reference material from ash material. Guidelines were developed for sampling, sample preparation and analysis, and leaching tests. Furthermore, a quality control system, including sampling strategies, sample analysis and leaching testing, was established

Alcohol combustion chemistry

KAUST Repository

Sarathy, Mani

2014-10-01

Alternative transportation fuels, preferably from renewable sources, include alcohols with up to five or even more carbon atoms. They are considered promising because they can be derived from biological matter via established and new processes. In addition, many of their physical-chemical properties are compatible with the requirements of modern engines, which make them attractive either as replacements for fossil fuels or as fuel additives. Indeed, alcohol fuels have been used since the early years of automobile production, particularly in Brazil, where ethanol has a long history of use as an automobile fuel. Recently, increasing attention has been paid to the use of non-petroleum-based fuels made from biological sources, including alcohols (predominantly ethanol), as important liquid biofuels. Today, the ethanol fuel that is offered in the market is mainly made from sugar cane or corn. Its production as a first-generation biofuel, especially in North America, has been associated with publicly discussed drawbacks, such as reduction in the food supply, need for fertilization, extensive water usage, and other ecological concerns. More environmentally friendly processes are being considered to produce alcohols from inedible plants or plant parts on wasteland. While biofuel production and its use (especially ethanol and biodiesel) in internal combustion engines have been the focus of several recent reviews, a dedicated overview and summary of research on alcohol combustion chemistry is still lacking. Besides ethanol, many linear and branched members of the alcohol family, from methanol to hexanols, have been studied, with a particular emphasis on butanols. These fuels and their combustion properties, including their ignition, flame propagation, and extinction characteristics, their pyrolysis and oxidation reactions, and their potential to produce pollutant emissions have been intensively investigated in dedicated experiments on the laboratory and the engine scale

Modelling combustion reactions for gas flaring and its resulting emissions

Directory of Open Access Journals (Sweden)

O. Saheed Ismail

2016-07-01

Full Text Available Flaring of associated petroleum gas is an age long environmental concern which remains unabated. Flaring of gas maybe a very efficient combustion process especially steam/air assisted flare and more economical than utilization in some oil fields. However, it has serious implications for the environment. This study considered different reaction types and operating conditions for gas flaring. Six combustion equations were generated using the mass balance concept with varying air and combustion efficiency. These equations were coded with a computer program using 12 natural gas samples of different chemical composition and origin to predict the pattern of emission species from gas flaring. The effect of key parameters on the emission output is also shown. CO2, CO, NO, NO2 and SO2 are the anticipated non-hydrocarbon emissions of environmental concern. Results show that the quantity and pattern of these chemical species depended on percentage excess/deficiency of stoichiometric air, natural gas type, reaction type, carbon mass content, impurities, combustion efficiency of the flare system etc. These emissions degrade the environment and human life, so knowing the emission types, pattern and flaring conditions that this study predicts is of paramount importance to governments, environmental agencies and the oil and gas industry.

Development of flameless combustion; Desarrollo de la combustion sin flama

Energy Technology Data Exchange (ETDEWEB)

Flores Sauceda, M. Leonardo; Cervantes de Gortari, Jaime Gonzalo [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)]. E-mail: 8344afc@prodigy.net.mx; jgonzalo@servidor.unam.mx

2010-11-15

The paper intends contribute to global warming mitigation joint effort that develops technologies to capture the CO{sub 2} produced by fossil fuels combustion and to reduce emission of other greenhouse gases like the NO{sub x}. After reviewing existing combustion bibliography is pointed out that (a) touches only partial aspects of the collective system composed by Combustion-Heat transfer process-Environment, whose interactions are our primary interest and (b) most specialists think there is not yet a clearly winning technology for CO{sub 2} capture and storage. In this paper the study of combustion is focused as integrated in the aforementioned collective system where application of flameless combustion, using oxidant preheated in heat regenerators and fluent gas recirculation into combustion chamber plus appropriated heat and mass balances, simultaneously results in energy saving and environmental impact reduction. [Spanish] El trabajo pretende contribuir al esfuerzo conjunto de mitigacion del calentamiento global que aporta tecnologias para capturar el CO{sub 2} producido por la combustion de combustibles fosiles y para disminuir la emision de otros gases invernadero como NOx. De revision bibliografica sobre combustion se concluye que (a) trata aspectos parciales del sistema compuesto por combustion-proceso de trasferencia de calor-ambiente, cuyas interacciones son nuestro principal interes (b) la mayoria de especialistas considera no hay todavia una tecnologia claramente superior a las demas para captura y almacenaje de CO{sub 2}. Se estudia la combustion como parte integrante del mencionado sistema conjunto, donde la aplicacion de combustion sin flama, empleando oxidante precalentado mediante regeneradores de calor y recirculacion de gases efluentes ademas de los balances de masa y energia adecuados, permite tener simultaneamente ahorros energeticos e impacto ambiental reducido.

Characterization of Site for Installing Open Loop Ground Source Heat Pump System

Science.gov (United States)

Yun, S. W.; Park, Y.; Lee, J. Y.; Yi, M. J.; Cha, J. H.

2014-12-01

This study was conducted to understand hydrogeological properties of site where open loop ground source heat pump system will be installed and operated. Groundwater level and water temperature were hourly measured at the well developed for usage of open loop ground source heat pump system from 11 October 2013 to 8 January 2014. Groundwater was sampled in January and August 2013 and its chemical and isotopic compositions were analyzed. The bedrock of study area is the Jurassic granodiorite that mainly consists of quartz (27.9 to 46.8%), plagioclase (26.0 to 45.5%), and alkali feldspar (9.5 to 18.7%). The groundwater level ranged from 68.30 to 68.94 m (above mean sea level). Recharge rate was estimated using modified watertable fluctuation method and the recharge ratios was 9.1%. The water temperature ranged from 14.8 to 15.0oC. The vertical Increase rates of water temperature were 1.91 to 1.94/100 m. The water temperature showed the significant seasonal variation above 50 m depth, but had constant value below 50 m depth. Therefore, heat energy of the groundwater can be used securely in open loop ground source heat pump system. Electrical conductivity ranged from 120 to 320 µS/cm in dry season and from 133 to 310 µS/cm in wet season. The electrical conductivity gradually decreased with depth. In particular, electrical conductivity in approximately 30 m depth decreased dramatically (287 to 249 µS/cm) in wet season. The groundwater was Ca-HCO3 type. The concentrations of dissolved components did not show the vertically significant variations from 0 to 250 m depth. The δ18O and δD ranged from -9.5 to -9.4‰ and from -69 to -68‰. This work is supported by the New and Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No.20123040110010).

Computational Study of Stratified Combustion in an Optical Diesel Engine

KAUST Repository

Jaasim, Mohammed

2017-03-28

Full cycle simulations of KAUST optical diesel engine were conducted in order to provide insights into the details of fuel spray, mixing, and combustion characteristics at different start of injection (SOI) conditions. Although optical diagnostics provide valuable information, the high fidelity simulations with matched parametric conditions improve fundamental understanding of relevant physical and chemical processes by accessing additional observables such as the local mixture distribution, intermediate species concentrations, and detailed chemical reaction rates. Commercial software, CONVERGE™, was used as the main simulation tool, with the Reynolds averaged Navier-Stokes (RANS) turbulence model and the multi-zone (SAGE) combustion model to compute the chemical reaction terms. SOI is varied from late compression ignition (CI) to early partially premixed combustion (PPC) conditions. The simulation results revealed a stronger correlation between fuel injection timing and combustion phasing for late SOI conditions, whereas the combustion phasing starts to decouple from SOI for early SOI cases. The predictions are consistent with the experimental observations, in terms of the overall trends in combustion and emission characteristics, while the high fidelity simulations provided further insights into the effects of mixture stratifications resulting from different SOI conditions.

Seismic proving test of BWR primary loop recirculation system

International Nuclear Information System (INIS)

Sato, H.; Shigeta, M.; Karasawa, Y.

1987-01-01

The seismic proving test of BWR Primary Loop Recirculation system is the second test to use the large-scale, high-performance vibration table of Tadotsu Engineering Laboratory. The purpose of this test is to prove the seismic reliability of the primary loop recirculation system (PLR), one of the most important safety components in the BWR nuclear plants, and also to confirm the adequacy of seismic analysis method used in the current seismic design. To achieve the purpose, the test was conducted under conditions and scale as near as possible to actual systems. The strength proving test was carried out with the test model mounted on the vibration table in consideration of basic design earthquake ground motions and other conditions to confirm the soundness of structure and the strength against earthquakes. Detailed analysis and analytic evaluation of the data obtained from the test was conducted to confirm the adequacy of the seismic analysis method and earthquake response analysis method used in the current seismic design. Then, on the basis of the results obtained, the seismic safety and reliability of BWR primary loop recirculation of the actual plants was fully evaluated

The effect of microwave pretreatment on chemical looping gasification of microalgae for syngas production

International Nuclear Information System (INIS)

Hu, Zhifeng; Ma, Xiaoqian; Jiang, Enchen

2017-01-01

Highlights: • Microwave pretreatment is beneficial to chemical-looping gasification reaction. • Gasification efficiency and gas yield increased greatly under microwave pretreatment. • 60 s is the optimal microwave pretreatment time in CLG to produce syngas. • Suitable microwave pretreatment can make the structure of solid residue become loose. • 750 W is the optimal microwave pretreatment power in CLG to produce syngas. - Abstract: Chemical-looping gasification (CLG) of Chlorella vulgaris was carried out in a quartz tube reactor under different microwave pretreatment. The product fractional yields, conversion efficiency and analysis of performance parameters were analyzed in order to obtain the characterization and optimal conditions of microwave pretreatment for syngas production. The results indicate that microwave pretreatment is conducive to CLG reaction. Furthermore, the higher power or the longer time in the process of microwave pretreatment could not exhibit a better effect on CLG. In addition, 750 W and 60 s is the optimal microwave pretreatment power and time respectively to obtain a great reducibility of oxygen carrier, high conversion efficiency, high products yield and good LHV. The H_2 yield, LHV, gasification efficiency and gas yield increased obviously from 18.12%, 12.14 MJ/Nm"3, 59.76% and 1.04 Nm"3/kg of untreated Chlorella vulgaris to 24.55%, 13.13 MJ/Nm"3, 72.16% and 1.16 Nm"3/kg of the optimal microwave pretreatment condition, respectively.

Chemical characterization and toxicologic evaluation of airborne mixtures: chemical characterization of combusted inventory red and violet smoke mixes

International Nuclear Information System (INIS)

Rubin, I.B.; Buchanan, M.V.; Moneyhun, J.H.

1982-10-01

Red and violet smoke grenades (Grenade, Hand, Smoke, M18) were combusted within canvas tents and the combustion products were sampled and analyzed. Uncombusted red and violet smoke mixes from the same lots used to fill the combusted grenades were also analyzed. Approximately ten percent of the major dye component of the red smoke mix, methylaminoanthraquinone (MAA) was converted to aminoanthraquinones (1-AA and 2-AA). The violet smoke mix was formulated to contain 1,4-diamino-2,3-dihydroanthraquinone (DAA) and MAA. Upon combustion the DAA was converted almost completely to diaminoanthraquinone (DAA) which was a minor constituent of the uncombusted mix. As in the combusted red smoke mix, it was found that MAA was partially converted to aminoanthraquinones

Combustion Chamber Fluid Dynamics and Hypergolic Gel Propellant Chemistry Simulations for Selectable Thrust Rocket Engines

National Research Council Canada - National Science Library

Nusca, Michael J; Chen, Chiung-Chu; McQuaid, Michael J

2007-01-01

.... Computational fluid dynamics is employed to model the chemically reacting flow within a system's combustion chamber, and computational chemistry is employed to characterize propellant physical and reactive properties...

Design validation and performance of closed loop gas recirculation system

International Nuclear Information System (INIS)

Kalmani, S.D.; Majumder, G.; Mondal, N.K.; Shinde, R.R.; Joshi, A.V.

2016-01-01

A pilot experimental set up of the India Based Neutrino Observatory's ICAL detector has been operational for the last 4 years at TIFR, Mumbai. Twelve glass RPC detectors of size 2 × 2 m 2 , with a gas gap of 2 mm are under test in a closed loop gas recirculation system. These RPCs are continuously purged individually, with a gas mixture of R134a (C 2 H 2 F 4 ), isobutane (iC 4 H 10 ) and sulphur hexafluoride (SF 6 ) at a steady rate of 360 ml/h to maintain about one volume change a day. To economize gas mixture consumption and to reduce the effluents from being released into the atmosphere, a closed loop system has been designed, fabricated and installed at TIFR. The pressure and flow rate in the loop is controlled by mass flow controllers and pressure transmitters. The performance and integrity of RPCs in the pilot experimental set up is being monitored to assess the effect of periodic fluctuation and transients in atmospheric pressure and temperature, room pressure variation, flow pulsations, uniformity of gas distribution and power failures. The capability of closed loop gas recirculation system to respond to these changes is also studied. The conclusions from the above experiment are presented. The validations of the first design considerations and subsequent modifications have provided improved guidelines for the future design of the engineering module gas system.

Mercury from combustion sources: a review of the chemical species emitted and their transport in the atmosphere

International Nuclear Information System (INIS)

Carpi, A.

1997-01-01

Different species of mercury have different physical/chemical properties and thus behave quite differentially in air pollution control equipment and in the atmosphere. In general, emission of mercury from coal combustion sources are approximately 20-50% elemental mercury (Hg 0 ) and 50-80% divalent mercury (Hg(II)), which may be predominantly HgCl 2 . Emissions of mercury from waste incinerators are approximately 10-20% Hg 0 and 75-85% Hg(II). The partitioning of mercury in flue gas between the elemental and divalent forms may be dependent on the concentration of particulate carbon, HCl and other pollutants in the stack emissions. The emission of mercury from combustion facilities depends on the species in the exhaust stream and the type of air pollution control equipment used at the source. Air pollution control equipment for mercury removal at combustion facilities includes activated carbon injection, sodium sulfide injection and wet lime/limestone flue gas desulfurization. White Hg(II) is water-soluble and may be removed form the atmosphere by wet and dry deposition close to the combustion sources, the combination of a high vapor pressure and low water-solubility facilitate the long-range transport of Hg 0 in the atmosphere. Background mercury in the atmosphere is predominantly Hg 0 . Elemental mercury is eventually removed from the atmosphere by dry deposition onto surfaces and by wet deposition after oxidation to water-soluble, divalent mercury. 62 refs., 2 figs., 1 tab

Failure probability of PWR reactor coolant loop piping

International Nuclear Information System (INIS)

Lo, T.; Woo, H.H.; Holman, G.S.; Chou, C.K.

1984-02-01

This paper describes the results of assessments performed on the PWR coolant loop piping of Westinghouse and Combustion Engineering plants. For direct double-ended guillotine break (DEGB), consideration was given to crack existence probability, initial crack size distribution, hydrostatic proof test, preservice inspection, leak detection probability, crack growth characteristics, and failure criteria based on the net section stress failure and tearing modulus stability concept. For indirect DEGB, fragilities of major component supports were estimated. The system level fragility was then calculated based on the Boolean expression involving these fragilities. Indirect DEGB due to seismic effects was calculated by convolving the system level fragility and the seismic hazard curve. The results indicate that the probability of occurrence of both direct and indirect DEGB is extremely small, thus, postulation of DEGB in design should be eliminated and replaced by more realistic criteria

Can we observe open loop transfer functions in a stochastic feedback system ?

International Nuclear Information System (INIS)

Kishida, Kuniharu; Suda, Nobuhide.

1991-01-01

There are two kinds of problems concerning open loop and closed loop transfer functions in a feedback system. One is a problem even in the deterministic case, and the other is in the stochastic case. In the deterministic case it is guaranteed under a necessary and sufficient condition that total sum of degrees of sub-transfer functions coincides to the degree of the total system. In the stochastic case a systematic understanding of a physical state model, a theoretical innovation model and a data-oriented innovation model is indispensable for determination of open loop transfer functions from time series data. Undesirable factors appear in determination of open loop transfer functions, since a transfer function matrix from input noises to output variables has a redundancy factor of diagonal matrix. (author)

Systems and methods of storing combustion waste products

Science.gov (United States)

Chen, Shen-En; Wang, Peng; Miao, Xiexing; Feng, Qiyan; Zhu, Qianlin

2016-04-12

In one aspect, methods of storing one or more combustion waste products are described herein. Combustion waste products stored by a method described herein can include solid combustion waste products such as coal ash and/or gaseous combustion products such as carbon dioxide. In some embodiments, a method of storing carbon dioxide comprises providing a carbon dioxide storage medium comprising porous concrete having a macroporous and microporous pore structure and flowing carbon dioxide captured from a combustion flue gas source into the pore structure of the porous concrete.

Energetic Combustion Devices for Aerospace Propulsion and Power

Science.gov (United States)

Litchford, Ron J.

2000-01-01

Chemical reactions have long been the mainstay thermal energy source for aerospace propulsion and power. Although it is widely recognized that the intrinsic energy density limitations of chemical bonds place severe constraints on maximum realizable performance, it will likely be several years before systems based on high energy density nuclear fuels can be placed into routine service. In the mean time, efforts to develop high energy density chemicals and advanced combustion devices which can utilize such energetic fuels may yield worthwhile returns in overall system performance and cost. Current efforts in this vein are being carried out at NASA MSFC under the direction of the author in the areas of pulse detonation engine technology development and light metals combustion devices. Pulse detonation engines are touted as a low cost alternative to gas turbine engines and to conventional rocket engines, but actual performance and cost benefits have yet to be convincingly demonstrated. Light metal fueled engines also offer potential benefits in certain niche applications such as aluminum/CO2 fueled engines for endo-atmospheric Martian propulsion. Light metal fueled MHD generators also present promising opportunities with respect to electric power generation for electromagnetic launch assist. This presentation will discuss the applications potential of these concepts with respect to aero ace propulsion and power and will review the current status of the development efforts.

Reactor design and operation strategies for a large-scale packed-bed CLC power plant with coal syngas

NARCIS (Netherlands)

Spallina, V.; Chiesa, P.; Martelli, E; Gallucci, F.; Romano, M.C.; Lozza, G.; Sint Annaland, van M.

2015-01-01

This paper deals with the design and operation strategies of dynamically operated packed-bed reactors (PBRs) of a chemical looping combustion (CLC) system included in an integrated gasification combined cycle (IGCC) for electric power generation with low CO2 emission from coal. The CLC reactors,

RECOVERY AND SEQUESTRATION OF CO2 FROM STATIONARY COMBUSTION SYSTEMS BY PHOTOSYNTHESIS OF MICROALGAE

Energy Technology Data Exchange (ETDEWEB)

Dr. T. Nakamura; Dr. C.L. Senior

2001-03-01

Most of the anthropogenic emissions of carbon dioxide result from the combustion of fossil fuels for energy production. Photosynthesis has long been recognized as a means, at least in theory, to sequester anthropogenic carbon dioxide. Aquatic microalgae have been identified as fast growing species whose carbon fixing rates are higher than those of land-based plants by one order of magnitude. Physical Sciences Inc. (PSI), Aquasearch, and the Hawaii Natural Energy Institute at the University of Hawaii are jointly developing technologies for recovery and sequestration of CO{sub 2} from stationary combustion systems by photosynthesis of microalgae. The research is aimed primarily at demonstrating the ability of selected species of microalgae to effectively fix carbon from typical power plant exhaust gases. This report covers the reporting period from 1 October to 31 December 2000. During this period planning of chemostat experiments at Aquasearch was initiated. These experiments will be used to select microalgae for the photobioreactor demonstrations. An initial survey of techniques for removing CO{sub 2} from coal-fired flue gas was begun. Chemical adsorption using MEA is the most mature technology and looks to be the most economically viable in the near future.

A sustained-arc ignition system for internal combustion engines

Science.gov (United States)

Birchenough, A. G.

1977-01-01

A sustained-arc ignition system was developed for internal combustion engines. It produces a very-long-duration ignition pulse with an energy in the order of 100 millijoules. The ignition pulse waveform can be controlled to predetermined actual ignition requirements. The design of the sustained-arc ignition system is presented in the report.

Determination of (BTEX) of the gasoline's combustion in Ecuador

International Nuclear Information System (INIS)

Garcia, Nelson; Insuasti, Alicia

1998-01-01

The contents of benzene, toluene, ethyl benzene and xylenes (BTEX) were determined and quantified in the gasoline's combustion on an internal combustion engine. Gas chromatography with flame ionization detector were used for chemical determinations

HERCULES Advanced Combustion Concepts Test Facility: Spray/Combustion Chamber

Energy Technology Data Exchange (ETDEWEB)

Herrmann, K. [Eidgenoessische Technische Hochschule (ETH), Labor fuer Aerothermochemie und Verbrennungssysteme, Zuerich (Switzerland)

2004-07-01

This yearly report for 2004 on behalf of the Swiss Federal Office of Energy (SFOE) at the Laboratory for Aero-thermochemistry and Combustion Systems at the Federal Institute of Technology ETH in Zurich, Switzerland, presents a review of work being done within the framework of HERCULES (High Efficiency R and D on Combustion with Ultra Low Emissions for Ships) - the international R and D project concerning new technologies for ships' diesels. The work involves the use and augmentation of simulation models. These are to be validated using experimental data. The report deals with the development of an experimental set-up that will simulate combustion in large two-stroke diesel engines and allow the generation of reference data. The main element of the test apparatus is a spray / combustion chamber with extensive possibilities for optical observation under variable flow conditions. The results of first simulations confirm concepts and shall help in further work on the project. The potential offered by high-speed camera systems was tested using the institute's existing HTDZ combustion chamber. Further work to be done is reviewed.

Chemical decontamination of Santa Maria de Garona NPP recirculation loops

Energy Technology Data Exchange (ETDEWEB)

Coello, R. [Santa Maria de Garona NPP - NUCLENOR, S.A. (Spain)

2002-07-01

Santa Maria de Garona is a boiling water reactor (BWR-3) with a Primary Containment type Mark 1. Its electrical power is 466 Mw and began its commercial operation in 1971. The plant currently operates in 24 month cycles. The reactor water recirculation system (RWRS) is composed of two independent loops. Each of them has a one stage vertical centrifugal recirculation pump, with a nominal flow of 2020 l/s, and ten jet pumps. It is worthy of mention that in 1986 it was started to inject hydrogen into the feedwater (concentration = 0,3 mg/l) in order to implement the chemical condition known as hydrogen water chemistry (HWC) in the primary circuit. The objective was to create an electrochemical potential below -230 mV in the RWRS which is assumed to be low enough to mitigate the intergranular stress corrosion cracking phenomena (IGSCC) in the sensitized austenitic stainless steels. Later, in 1994, the hydrogen concentration in the feedwater was increased to 0,9 mg/l in order to obtain the protection's ECP in the bottom of the reactor vessel. This feedwater hydrogen concentration has been maintained since then. The nature of the oxides that are formed in the RWRS is strongly affected by the electrochemical conditions (ECP) which have been maintained in this system. It is frequent to find oxides like Fe{sub 2}O{sub 3} (hematite), Fe{sub 3}O{sub 4} (magnetite), NiFe{sub 2}O{sub 4} (trevorite), Cr{sub 2} FeO{sub 4} (chromite), Fe{sub 3-x-y} Cr{sub x} Ni{sub y} O{sub 4} (spinels), etc. However, it is normal to find a combination of all of them in various proportions, depending on the ECP established. Radioactive isotopes of the transition metals ({sup 60}Co, {sup 54}Mn, {sup 51}Cr, {sup 59}Fe, etc.) also participate in these oxides and contribute greatly to increase the dose rate in the circuit. The chemical decontamination processes are designed for the effective dissolution of the metallic oxides present and therefore the type of process to be applied will depend

GOTHIC-3D applicability to hydrogen combustion analysis

International Nuclear Information System (INIS)