The Experts below are selected from a list of 346518 Experts worldwide ranked by ideXlab platform
Fengrui Sun - One of the best experts on this subject based on the ideXlab platform.
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Performance comparison of an irreversible closed variable-temperature heat reservoir brayton cycle under Maximum Power density and Maximum Power conditions
Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 2005Co-Authors: Lingen Chen, Junlin Zheng, Fengrui SunAbstract:The Power density is taken as an objective for performance analysis of an irreversible closed Brayton cycle coupled to variable-temperature heat reservoirs. The analytical formulas about the relationship between Power density and working fluid temperature ratio (pressure ratio) are derived with the heat resistance losses in the hot- and cold-side heat exchangers, the irreversible compression and expansion losses in the compressor and turbine, and the effect of the finite thermal capacity rate of the heat reservoirs. The obtained results are compared with those results obtained by using the Maximum Power criterion. The influences of some design parameters, including the temperature ratio of the heat reservoirs, the effective-nesses of the heat exchangers between the working fluid and the heat reservoirs, and the efficiencies of the compressor and the turbine, on the Maximum Power density are provided by numerical examples, and the advantages and disadvantages of Maximum Power density design are analysed. The Power plant design with Maximum Power density leads to a higher efficiency and smaller size. When the heat transfers between the working fluid and the heat reservoirs are carried out ideally and the thermal capacity rates of the heat reservoirs are infinite, the results of this article become similar to those obtained in the recent literature.
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performance comparison of an endoreversible closed variable temperature heat reservoir brayton cycle under Maximum Power density and Maximum Power conditions
Energy Conversion and Management, 2002Co-Authors: Lingen Chen, Junlin Zheng, Fengrui SunAbstract:In this paper, the Power density, defined as the ratio of Power output to Maximum specific volume in the cycle, is taken as the objective for performance analysis of an endoreversible closed Brayton cycle coupled to variable temperature heat reservoirs in the viewpoint of finite time thermodynamics or entropy generation minimization. The analytical formulae about the relations between Power density and pressure ratio are derived with heat resistance losses in the hot and cold side heat exchangers. The obtained results are compared with those results obtained by using the Maximum Power criterion. The influences of some design parameters on the Maximum Power density are provided by numerical examples, and the advantages and disadvantages of Maximum Power density design are analyzed. The Power plant design with Maximum Power density leads to a higher efficiency and smaller size. When the heat transfer is effected ideally and the thermal capacity rates of the two heat reservoirs are infinite, the results of this paper become those obtained in recent literature.
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Performance comparison of an irreversible closed Brayton cycle under Maximum Power density and Maximum Power conditions
Exergy An International Journal, 2002Co-Authors: Lingen Chen, Junlin Zheng, Fengrui SunAbstract:Abstract In this paper, the Power density, defined as the ratio of Power output to the Maximum specific volume in the cycle, is taken as objective for performance analysis of an irreversible closed Brayton cycle coupled to constant-temperature heat reservoirs in the viewpoint of finite time thermodynamics (FTT) or entropy generation minimization (EGM). The analytical formulas about the relations between Power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the irreversible compression and expansion losses in the compressor and turbine. The obtained results are compared with those results obtained by using the Maximum Power criterion. The influences of some design parameters on the Maximum Power density are provided by numerical examples, and the advantages and disadvantages of Maximum Power density design are analyzed. The Power plant design with Maximum Power density leads to a higher efficiency and smaller size. However, the Maximum Power density design requires a higher pressure ratio than Maximum Power design. When the heat transfer is carried out ideally, the results of this paper become those obtained in recent literature.
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Efficiency of an Atkinson engine at Maximum Power density
Energy Conversion and Management, 1998Co-Authors: Lingen Chen, Junxing Lin, Fengrui SunAbstract:In studies of finite-time thermodynamics, most performance analyses concern the Maximum Power output and the corresponding efficiency for heat engines. In this paper, instead of just maximizing Power for a cycle, the Power density (the ratio of the Power to the Maximum specific volume in the cycle) is maximized for an Atkinson engine. The results showed that the efficiency at Maximum Power density is always greater than that at Maximum Power, and the design parameters at Maximum Power density lead to smaller and more efficient Atkinson engines with larger pressure ratios.
Lingen Chen - One of the best experts on this subject based on the ideXlab platform.
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Performance comparison of an irreversible closed variable-temperature heat reservoir brayton cycle under Maximum Power density and Maximum Power conditions
Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 2005Co-Authors: Lingen Chen, Junlin Zheng, Fengrui SunAbstract:The Power density is taken as an objective for performance analysis of an irreversible closed Brayton cycle coupled to variable-temperature heat reservoirs. The analytical formulas about the relationship between Power density and working fluid temperature ratio (pressure ratio) are derived with the heat resistance losses in the hot- and cold-side heat exchangers, the irreversible compression and expansion losses in the compressor and turbine, and the effect of the finite thermal capacity rate of the heat reservoirs. The obtained results are compared with those results obtained by using the Maximum Power criterion. The influences of some design parameters, including the temperature ratio of the heat reservoirs, the effective-nesses of the heat exchangers between the working fluid and the heat reservoirs, and the efficiencies of the compressor and the turbine, on the Maximum Power density are provided by numerical examples, and the advantages and disadvantages of Maximum Power density design are analysed. The Power plant design with Maximum Power density leads to a higher efficiency and smaller size. When the heat transfers between the working fluid and the heat reservoirs are carried out ideally and the thermal capacity rates of the heat reservoirs are infinite, the results of this article become similar to those obtained in the recent literature.
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performance comparison of an endoreversible closed variable temperature heat reservoir brayton cycle under Maximum Power density and Maximum Power conditions
Energy Conversion and Management, 2002Co-Authors: Lingen Chen, Junlin Zheng, Fengrui SunAbstract:In this paper, the Power density, defined as the ratio of Power output to Maximum specific volume in the cycle, is taken as the objective for performance analysis of an endoreversible closed Brayton cycle coupled to variable temperature heat reservoirs in the viewpoint of finite time thermodynamics or entropy generation minimization. The analytical formulae about the relations between Power density and pressure ratio are derived with heat resistance losses in the hot and cold side heat exchangers. The obtained results are compared with those results obtained by using the Maximum Power criterion. The influences of some design parameters on the Maximum Power density are provided by numerical examples, and the advantages and disadvantages of Maximum Power density design are analyzed. The Power plant design with Maximum Power density leads to a higher efficiency and smaller size. When the heat transfer is effected ideally and the thermal capacity rates of the two heat reservoirs are infinite, the results of this paper become those obtained in recent literature.
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Performance comparison of an irreversible closed Brayton cycle under Maximum Power density and Maximum Power conditions
Exergy An International Journal, 2002Co-Authors: Lingen Chen, Junlin Zheng, Fengrui SunAbstract:Abstract In this paper, the Power density, defined as the ratio of Power output to the Maximum specific volume in the cycle, is taken as objective for performance analysis of an irreversible closed Brayton cycle coupled to constant-temperature heat reservoirs in the viewpoint of finite time thermodynamics (FTT) or entropy generation minimization (EGM). The analytical formulas about the relations between Power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the irreversible compression and expansion losses in the compressor and turbine. The obtained results are compared with those results obtained by using the Maximum Power criterion. The influences of some design parameters on the Maximum Power density are provided by numerical examples, and the advantages and disadvantages of Maximum Power density design are analyzed. The Power plant design with Maximum Power density leads to a higher efficiency and smaller size. However, the Maximum Power density design requires a higher pressure ratio than Maximum Power design. When the heat transfer is carried out ideally, the results of this paper become those obtained in recent literature.
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Efficiency of an Atkinson engine at Maximum Power density
Energy Conversion and Management, 1998Co-Authors: Lingen Chen, Junxing Lin, Fengrui SunAbstract:In studies of finite-time thermodynamics, most performance analyses concern the Maximum Power output and the corresponding efficiency for heat engines. In this paper, instead of just maximizing Power for a cycle, the Power density (the ratio of the Power to the Maximum specific volume in the cycle) is maximized for an Atkinson engine. The results showed that the efficiency at Maximum Power density is always greater than that at Maximum Power, and the design parameters at Maximum Power density lead to smaller and more efficient Atkinson engines with larger pressure ratios.
Shuhn Shyurng Hou - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis and comparison of an Atkinson cycle coupled to variable temperature heat reservoirs under Maximum Power and Maximum Power density conditions
Energy Conversion and Management, 2005Co-Authors: Pai-yi Wang, Shuhn Shyurng HouAbstract:In this paper, performance analysis and comparison based on the Maximum Power and Maximum Power density conditions have been conducted for an Atkinson cycle coupled to variable temperature heat reservoirs. The Atkinson cycle is internally reversible but externally irreversible, since there is external irreversibility of heat transfer during the processes of constant volume heat addition and constant pressure heat rejection. This study is based purely on classical thermodynamic analysis methodology. It should be especially emphasized that all the results and conclusions are based on classical thermodynamics. The Power density, defined as the ratio of Power output to Maximum specific volume in the cycle, is taken as the optimization objective because it considers the effects of engine size as related to investment cost. The results show that an engine design based on Maximum Power density with constant effectiveness of the hot and cold side heat exchangers or constant inlet temperature ratio of the heat reservoirs will have smaller size but higher efficiency, compression ratio, expansion ratio and Maximum temperature than one based on Maximum Power. From the view points of engine size and thermal efficiency, an engine design based on Maximum Power density is better than one based on Maximum Power conditions. However, due to the higher compression ratio and Maximum temperature in the cycle, an engine design based on Maximum Power density conditions requires tougher materials for engine construction than one based on Maximum Power conditions.
S. Lineykin - One of the best experts on this subject based on the ideXlab platform.
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Maximum Power point matching versus Maximum Power point tracking for solar generators
Renewable and Sustainable Energy Reviews, 2013Co-Authors: Alon Kuperman, Moshe Averbukh, S. LineykinAbstract:In this paper, a method of designing an optimally arranged solar array for converterless matching to a known linear load is proposed and compared to the classical Maximum Power Point Tracking method. Long-time performance of both methods is examined for three common types of loads under real weather conditions. Test results indicate that only in case of a pure resistive load the Maximum Power Point Tracking-based solar system advantage is undisputed. In case of a load represented by a voltage source with internal resistance, the long term energy productions of the system employing a practical Maximum Power Point Tracking operated converter is on a par or lower than the converterless system energy yield.
Hasbi Yavuz - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the stirling heat engine at Maximum Power conditions
Energy, 1997Co-Authors: L.berrin Erbay, Hasbi YavuzAbstract:The Stirling heat engine operating in a closed regenerative thermodynamic cycle is analyzed. Polytropic processes are used for the Power and displacement pistons. Following regeneration, the Maximum Power density and efficiency are found and the compression ratio at Maximum Power density is determined.
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Maximum Power density analysis of an irreversible Joule - Brayton engine
Journal of Physics D: Applied Physics, 1996Co-Authors: Bahri Sahin, Ali Kodal, Tamer Yilmaz, Hasbi YavuzAbstract:A performance analysis based on a Power density criterion has been carried out for an irreversible Joule - Brayton (JB) heat engine. The results obtained were compared with those of a Power performance criterion. It is shown that design parameters at Maximum Power density lead to smaller and more efficient JB engines than an engine working at Maximum Power output conditions. Due to irreversibilities in the heat engine, the Power and thermal efficiency will reduce by a certain amount, however the Maximum Power density conditions still give a better performance than at the Maximum Power output conditions. The analysis demonstrated in this paper may provide a basis for the determination of optimal operating conditions and the design parameters for real JB heat engines.
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Maximum Power density for an endoreversible carnot heat engine
Energy, 1996Co-Authors: Bahri̇ Şahi̇n, Ali Kodal, Hasbi YavuzAbstract:An analysis using Maximum Power-density criteria has been carried out for an endoreversible Carnot heat engine. The results have been compared with known results on Maximum Power analysis. The design parameters at Maximum Power density lead to smaller and more efficient endoreversible Carnot heat engines than those working at Maximum Power output.
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Efficiency of a Joule-Brayton engine at Maximum Power density
Journal of Physics D: Applied Physics, 1995Co-Authors: Bahri Sahin, Ali Kodal, Hasbi YavuzAbstract:A new kind of Power analysis is conducted on a reversible Joule-Brayton cycle. Although many performance analyses have been carried out resulting in famous efficiencies (Carnot, Curzon-Ahlborn), most do not consider the sizes of the engines. In the studies of Curzon and Ahlborn and others, researchers utilized the thermal efficiency at Maximum Power as an efficiency standard for practical heat engines. In this paper, instead of just maximizing Power for certain cycle parameters, the Power density defined as the ratio of Power to the Maximum specific volume in the cycle, is maximised. Therefore the effects of the engine sizes were included in the analysis. The result showed a new type of efficiency at the Maximum Power density which is always greater than that at the Maximum Power (Curzon-Ahlborn efficiency). Evaluations show that design parameters at the Maximum Power density lead to smaller and more efficient Joule-Brayton engines.
