The Experts below are selected from a list of 10812 Experts worldwide ranked by ideXlab platform
Marc A Rosen - One of the best experts on this subject based on the ideXlab platform.
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performance comparison of two Combined sofc Gas Turbine systems
Journal of Power Sources, 2007Co-Authors: Mikhail Granovskii, Ibrahim Dincer, Marc A RosenAbstract:Abstract A necessary step in the use of natural Gas (methane) in solid oxide fuel cells (SOFCs) is its preliminary conversion to hydrogen and carbon monoxide. To perform methane conversion within fuel cells and avoid catalyst carbonization the molar ratio between methane and steam (or steam with carbon dioxide) should be 1:2 or higher at the SOFC inlet. In this article two possible technological approaches to provide this desirable ratio in a Combined SOFC–Gas Turbine system are compared. The first approach involves generation of the required steam in the coupled Gas Turbine cycle. The second (which is more traditional) involves recycling some part of the exhaust Gases around the anodes of the SOFC stack. Exergy and energy analyses for the two SOFC–Gas Turbine systems are conducted to determine their efficiencies and capabilities to generate power at different rates of oxygen conductivity through the SOFC electrolyte (ion conductive membrane), as well as various efficiencies for natural Gas conversion to electricity in the SOFC stack. It is determined that with a fixed SOFC stack the scheme with recycling has higher exergy and energy efficiencies (requiring less natural Gas for a fixed electricity output) and the scheme with steam generation is associated with a higher capability for power generation. The question of which scheme permits a higher reduction in natural Gas consumption (per unit of time), in the case of its implementation instead of a contemporary Combined Gas Turbine–steam power cycle is considered. The greater capability of power generation while retaining high efficiency of fuel consumption in the scheme with steam generation makes its implementation more favorable. This scheme provides a better relative reduction in natural Gas consumption (relative to the scheme with exhaust Gas recycling) calculated per unit of time which reaches values of about 20%. At higher values of oxygen conductivity and efficiency of natural Gas conversion to electricity in the SOFC stack this relative reduction becomes less significant, remaining in the range of 3–8%.
K. Bahlouli - One of the best experts on this subject based on the ideXlab platform.
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Comprehensive analysis of energy, exergy and exergo-economic of cogeneration of heat and power in a Combined Gas Turbine and organic Rankine cycle
Energy Conversion and Management, 2015Co-Authors: M. Khaljani, Rahim Khoshbakhti Saray, K. BahlouliAbstract:Organic Rankine cycles (ORCs) are appropriate technology for the conversion of low quality thermal energy to electrical power. Meanwhile the waste heat from the exhaust Gases of the top cycle of the energy conversion systems to the environment is prevented. The aim of this work is thermodynamic, exergo-economic and environmental assessment of a cogeneration of heat and power cycle (CHP), considering the three objective functions of first and second law efficiencies and the total cost rates of the system. The proposed Combined heat and power cycle combines a Gas Turbine (GT) and an ORC through a single-pressure heat recovery steam generator (HRSG). In this regard, after the thermodynamic simulation of the cycle, validations of the results of top and bottom cycles are evaluated using the works available in the literature. The results show that the most exergy destruction rate takes place in the combustion chamber, and after that in heat recovery steam generator and Gas Turbine, respectively. The exergo-economic factor for the whole cycle is 10.59% indicating that the exergy destruction cost rate is more than capital investment cost rate. In order to assess the effects of design parameters on the objective functions, a parametric study is conducted. The results reveal that the increase in pressure ratio and isentropic efficiency of air compressor and Gas Turbine efficiency improves thermodynamic performance of the system, however, the more increase of these parameters deteriorates the total cost rates. Furthermore, the increase in air preheater exiting temperature will be useful for the system both in terms of thermodynamic and exergo-economic. The increase in the condensation temperature and pinch point temperature difference of evaporator of ORC and increase in pinch point temperature difference of heat recovery steam generator cause the first and second law efficiency to fall down and also to increase the total cost rates of the system.
Seyed Ehsan Shakib - One of the best experts on this subject based on the ideXlab platform.
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cost optimization of a Combined power and water desalination plant with exergetic environment and reliability consideration
Desalination, 2012Co-Authors: Seyed Reza Hosseini, Majid Amidpour, Seyed Ehsan ShakibAbstract:Abstract The present study deals with the multi-objective optimization for designing a Combined Gas Turbine and multi stage flash desalination plant. In optimization approach, the exergetic, economic and environmental aspects have been considered, simultaneously. In order to achieve the optimal design, Multi-objective genetic algorithm (MOGA) is applied as a suitable optimization technique. The thermoenvironomic objective function is obtained by integrating the environmental impacts and thermoeconomic objective. By applying the optimization approach, this objective function is minimized, whereas system exergy efficiency is maximized. Moreover, equipment reliability using the state-space and the continuous Markov method is incorporated in optimization results to improve the products' cost values. The optimization results show that the cost of products and environmental cost impact are reduced by 13.4% and 53.4%, respectively, whereas a 14.8% increase happens in total exergy efficiency. Therefore, improvement in all objectives has been achieved using the optimization process, although the power and water productions have not changed much. Additionally, the sensitivity analysis shows the relationship between the fuel cost, pollution damage cost and the objective functions.
Ibrahim Dincer - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic analysis of a Combined Gas Turbine power system with a solid oxide fuel cell through exergy
Thermochimica Acta, 2008Co-Authors: Yousef Haseli, Ibrahim Dincer, Greg F. NatererAbstract:This paper examines the exergetic performance of a high-temperature solid oxide fuel cell (SOFC) Combined with a conventional recuperative Gas Turbine (GT) plant. Individual models are developed for each component, specifically for SOFC and a combustor that is located downstream of the cell stack. The exergy destruction and efficiency of each component are derived and presented. Furthermore, the overall system is analyzed and its exergy efficiency, as well as exergy destruction, is computed. An assessment of the cycle is performed for an actual system and the results for certain operating conditions are compared with past published results. The comparisons provide useful verification of the thermal simulations in the present work. Further outcomes indicate that increasing the Turbine inlet temperature (TIT) results in decreasing the exergy and thermal efficiencies of the cycle, whereas it improves the total specific power output. Also, an increase in either TIT or compression ratio (rp) leads to a higher rate of exergy destruction of the plant. A comparison between the GT–SOFC plant and a traditional GT cycle, based on identical operating conditions, is also made. The superior performance of a GT–SOFC, in terms of thermal and exergy efficiencies, over a traditional GT cycle is evident: 26.6% and 27.8% better exergetic and energetic performance, respectively, than a traditional GT plant. In this case, the exergy and thermal efficiencies of the integrated cycle become as high as 57.9% and 60.6%, respectively, at the optimum compression ratio.
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performance comparison of two Combined sofc Gas Turbine systems
Journal of Power Sources, 2007Co-Authors: Mikhail Granovskii, Ibrahim Dincer, Marc A RosenAbstract:Abstract A necessary step in the use of natural Gas (methane) in solid oxide fuel cells (SOFCs) is its preliminary conversion to hydrogen and carbon monoxide. To perform methane conversion within fuel cells and avoid catalyst carbonization the molar ratio between methane and steam (or steam with carbon dioxide) should be 1:2 or higher at the SOFC inlet. In this article two possible technological approaches to provide this desirable ratio in a Combined SOFC–Gas Turbine system are compared. The first approach involves generation of the required steam in the coupled Gas Turbine cycle. The second (which is more traditional) involves recycling some part of the exhaust Gases around the anodes of the SOFC stack. Exergy and energy analyses for the two SOFC–Gas Turbine systems are conducted to determine their efficiencies and capabilities to generate power at different rates of oxygen conductivity through the SOFC electrolyte (ion conductive membrane), as well as various efficiencies for natural Gas conversion to electricity in the SOFC stack. It is determined that with a fixed SOFC stack the scheme with recycling has higher exergy and energy efficiencies (requiring less natural Gas for a fixed electricity output) and the scheme with steam generation is associated with a higher capability for power generation. The question of which scheme permits a higher reduction in natural Gas consumption (per unit of time), in the case of its implementation instead of a contemporary Combined Gas Turbine–steam power cycle is considered. The greater capability of power generation while retaining high efficiency of fuel consumption in the scheme with steam generation makes its implementation more favorable. This scheme provides a better relative reduction in natural Gas consumption (relative to the scheme with exhaust Gas recycling) calculated per unit of time which reaches values of about 20%. At higher values of oxygen conductivity and efficiency of natural Gas conversion to electricity in the SOFC stack this relative reduction becomes less significant, remaining in the range of 3–8%.
Mohammad Hossein Ahmadi - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic analysis of a Combined Gas Turbine orc cycle and absorption refrigeration for a cchp system
Applied Thermal Engineering, 2017Co-Authors: A Mohammadi, Alibakhsh Kasaeian, Fathollah Pourfayaz, Mohammad Hossein AhmadiAbstract:Abstract Hybrid power systems are gained more attention due to their better performance and higher efficiency. Widespread use of these systems improves environmental situation as they reduce the amount of fossil fuel consumption. In this paper a hybrid system composed of a Gas Turbine, an ORC cycle and an absorption refrigeration cycle is proposed as a Combined cooling, heating and power system for residential usage. Thermodynamic analysis is applied on the system. Also a parametric analysis is carried out to investigate the effect of different parameters on the system performance and output cooling, heating and power. The results show that under design conditions, the proposed plant can produce 30 kW power, 8 kW cooling and almost 7.2 ton hot water with an efficiency of 67.6%. Moreover, parametric analysis shows that pressure ratio and Gas Turbine inlet temperature are the most important and influential parameters. After these two, ORC Turbine inlet temperature is the most effective parameter as it can change both net output power and energy efficiency of the system.