The Experts below are selected from a list of 1356 Experts worldwide ranked by ideXlab platform
Antonio Calvo Hernandez - One of the best experts on this subject based on the ideXlab platform.
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solar driven sodium thermal electrochemical converter coupled to a brayton heat engine parametric optimization
Renewable Energy, 2021Co-Authors: Jincan Chen, Wanli Peng, Julian Gonzalezayala, Antonio Calvo HernandezAbstract:Abstract A novel high-efficiency device comprised of three subsystems, a solar collector, a sodium thermal electrochemical converter, and a non-recuperative Brayton heat engine, is modeled by taking into account the main internal and External Irreversibility sources. The model extends previous works in which the heat waste of the electrochemical converter is used as heat input in a Brayton gas turbine to study its performance and feasibility when a solar energy input is added. The operative working temperatures of three subsystems are determined by energy balance equations. The dependence of the efficiency and power output of the overall system on the solar concentration ratio, the current density, the thickness of the electrolyte, and the adiabatic pressure ratio (or temperature ratio) of the Brayton cycle is discussed in detail. The maximum efficiencies and power output densities are calculated and the states of the maximum efficiency-power density are determined under different given solar concentration ratios. The parametric optimum selection criteria of a number of critical parameters of the overall system are provided and the matching problems of the three subsystems are properly addressed. It is found that under a solar concentration around 1350, the maximum efficiency and power output density of the proposed hybrid system can reach, respectively, 29.6% and 1.23 × 10 5 W/m2. These values amount approximately 32.7% and 156% compared to those of the solar-driven sodium thermal electrochemical converter system without the bottoming Brayton cycle. The Pareto front obtained from numerical multi-objective and multi-parametric methods endorses previous findings.
Wanli Peng - One of the best experts on this subject based on the ideXlab platform.
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solar driven sodium thermal electrochemical converter coupled to a brayton heat engine parametric optimization
Renewable Energy, 2021Co-Authors: Jincan Chen, Wanli Peng, Julian Gonzalezayala, Antonio Calvo HernandezAbstract:Abstract A novel high-efficiency device comprised of three subsystems, a solar collector, a sodium thermal electrochemical converter, and a non-recuperative Brayton heat engine, is modeled by taking into account the main internal and External Irreversibility sources. The model extends previous works in which the heat waste of the electrochemical converter is used as heat input in a Brayton gas turbine to study its performance and feasibility when a solar energy input is added. The operative working temperatures of three subsystems are determined by energy balance equations. The dependence of the efficiency and power output of the overall system on the solar concentration ratio, the current density, the thickness of the electrolyte, and the adiabatic pressure ratio (or temperature ratio) of the Brayton cycle is discussed in detail. The maximum efficiencies and power output densities are calculated and the states of the maximum efficiency-power density are determined under different given solar concentration ratios. The parametric optimum selection criteria of a number of critical parameters of the overall system are provided and the matching problems of the three subsystems are properly addressed. It is found that under a solar concentration around 1350, the maximum efficiency and power output density of the proposed hybrid system can reach, respectively, 29.6% and 1.23 × 10 5 W/m2. These values amount approximately 32.7% and 156% compared to those of the solar-driven sodium thermal electrochemical converter system without the bottoming Brayton cycle. The Pareto front obtained from numerical multi-objective and multi-parametric methods endorses previous findings.
Rene Tchinda - One of the best experts on this subject based on the ideXlab platform.
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thermo ecological analysis and optimization of a three heat reservoir absorption heat pump with two internal irreversibilities and External Irreversibility
International Journal of Refrigeration-revue Internationale Du Froid, 2019Co-Authors: Rodrigue Leo Fossi Nemogne, Brigitte Astrid Medjo Nouadje, Paiguy Armand Ngouateu Wouagfack, Rene TchindaAbstract:Abstract The investigations carried out in this work concern the optimization and the thermodynamic analysis of an absorption heat pump with multi-irreversibilities and provided with three-heat-reservoir mainly using the thermo-ecological criterion as objective function. The thermodynamic analysis of the first and second laws of thermodynamics and the linear law of heat-transfer allowed us to evaluate and optimize the objective functions of performance such as: the specific heating load, the coefficient of performance, the specific entropy generation rate, the ecological coefficient of performance and the heat-transfer areas of the various components. These allowed us to study the variations of these criteria according to the design parameters and the temperatures of the working fluid in the components. From this study, it follows that the optimal system implies a maximum thermo-ecological coefficient, a minimum entropy production rate corresponding to a certain value of the specific heating load, while maintaining a system which limits the losses between the condenser and the evaporator. Moreover, the consideration of the two internal irreversibilities, the External Irreversibility and the losses of the heat resistances is very close to a real absorption heat pump and allows a more precise and objective study rather than in the optimization and the design of an absorption system like an endoreversible system.
Shengming Liao - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic multi objective optimization of a solar dish brayton system based on maximum power output thermal efficiency and ecological performance
Renewable Energy, 2016Co-Authors: Yuqiang Li, Shengming LiaoAbstract:Solar-dish Brayton system driven by the hybrid of fossil fuel and solar energy is characterized by continuously stable operation, simplified hybridization, low system costs and high thermal efficiency. In order to enable the system to operate with its highest capabilities, a thermodynamic multi-objective optimization was performed in this study based on maximum power output, thermal efficiency and ecological performance. A thermodynamic model was developed to obtain the dimensionless power output, thermal efficiency and ecological performance, in which the imperfect performance of parabolic dish solar collector, the External Irreversibility of Brayton heat engine and the conductive thermal bridging loss were considered. The combination of NSGA-II algorithm and decision makings was used to realize multi-objective optimization, where the temperatures of absorber, cooling water and working fluid, the effectiveness of hot-side heat exchanger, cold-side heat exchanger and regenerator were considered as optimization variables. Using the decision makings of Shannon Entropy, LINMAP and TOPSIS, the final optimal solutions were chosen from the Pareto frontier obtained by NSGA-II. By comparing the deviation index of each final optimal solution from the ideal solution, it is shown that the multi-objective optimization can lead to a more desirable design compared to the single-objective optimizations, and the final optimal solution selected by TOPSIS decision making presents superior performance. Moreover, the fitted curve between the optimal power output, thermal efficiency and ecological performance derived from Pareto frontier is obtained for better insight into the optimal design of the system. The sensitivity analysis shows that the optimal system performance is strongly dependent on the temperatures of absorber, cooling water and working fluid, and the effectiveness of regenerator. The results of this work offer benefits for related theoretic research and basis for solar energy industry.
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thermo economic multi objective optimization for a solar dish brayton system using nsga ii and decision making
International Journal of Electrical Power & Energy Systems, 2015Co-Authors: Shengming Liao, Gang LiuAbstract:Abstract A 100 kW regenerative Brayton heat engine driven by the hybrid of fossil fuel and solar energy was considered for optimization based on multiple criteria. A thermodynamic model of such hybrid system was developed so that the power output, thermal efficiency and dimensionless thermo-economic performance with the imperfect performance of parabolic dish solar collector, the External Irreversibility of Brayton heat engine and conductive thermal bridging loss could be obtained. Evolutionary algorithm based on NSGA-II (Elitist Non-dominated Sorting Genetic Algorithm) was employed to optimize triple-objective and dual-objective functions, where the temperatures of hot reservoir, cold reservoir and working fluid, the effectiveness of hot-side heat exchanger, cold-side heat exchanger and regenerator were considered as design variables. Using decision makings, including Shannon Entropy, LINMAP and TOPSIS methods, the final optimal solutions were selected from Pareto frontier obtained by NSGA-II. The results show that there exists an appropriate working fluid temperature to cause optimal solution under each given condition. The comparisons of triple-objective and dual-objective optimization with single-objective optimization indicate that multi-objective optimization can yield the more suitable results due to the lower deviation index from the ideal solution. In the analysis of triple-objective optimization, an expected result is obtained that the optimal values of the power out, efficiency and dimensionless thermo-economic performance of solar-dish Brayton system (68.65 kW, 0.2331 and 0.3077) are 22.6%, 34.9% and 18.4% respectively less than that of convectional Brayton heat engine. Finally, a range of functional relationship between the optimized objectives in Pareto frontier is fitted to provide more detailed insight into the optimal design of solar-dish Brayton system.
S C Kaushik - One of the best experts on this subject based on the ideXlab platform.
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a new thermoeconomic approach and parametric study of an irreversible regenerative brayton refrigeration cycle
International Journal of Refrigeration-revue Internationale Du Froid, 2006Co-Authors: S K Tyagi, Guangming Chen, Q Wang, S C KaushikAbstract:The detailed parametric study of an irreversible regenerative Brayton refrigerator cycle using the new thermoeconomic approach is presented in this paper. The External Irreversibility is due to finite temperature difference between the cycle and the External reservoirs while the internal irreversibilities are due to the nonisentropic compression and expansion processes and the regenerative loss. The thermoeconomic objective function defined as the cooling load per unit cost is optimized with respect to the state point temperatures for a typical set of operating conditions. The power input and cooling load are found to be decreasing functions of the expansion outlet temperature (T1), while it is the reverse in the case of COP. On the other hand, there are optimal values of the temperature T1, cooling load, power input and COP at which the cycle attains the maximum objective function for a typical set of operating parameters. Again, the objective function, COP and cooling load further enhance, while the power input goes down, as the various values of the effectiveness or efficiency components are increased.
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parametric study of an irreversible regenerative brayton cycle with isothermal heat addition
Energy Conversion and Management, 2003Co-Authors: S C Kaushik, S K Tyagi, M K SinghalAbstract:Abstract A parametric study of an irreversible regenerative Brayton heat engine with isothermal heat addition has been performed with External as well as internal irreversibilities. The External Irreversibility is due to the finite temperature differences between the heat engine and the External reservoirs, while the internal irreversiblities are due to other processes, viz. nonisentropic compression and expansion processes in the compressor and turbine, respectively, and the regenerative heat loss. The power output is maximized with respect to the working fluid temperatures, and the effects of different parameters on the maximum power output and the corresponding thermal efficiency have been studied. There is a significant improvement in the thermal efficiency (above 15%) of a Brayton cycle with isothermal heat addition over the conventional one. It is seen that the effect of the isobaric side effectiveness is rather pronounced for the power output and the corresponding thermal efficiency. The effect of the turbine efficiency is found to be more than that of the compressor on both power output and thermal efficiency. Also, it is seen that there are optimal values of the various heat capacitance rates between the different reservoirs and the heat engine.
