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Lingen Chen - One of the best experts on this subject based on the ideXlab platform.
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Modelling, Analyses and Optimization for Exergy Performance of an Irreversible Intercooled RegeneRated Brayton CHP Plant: Part 1 — Thermodynamic Modelling and Parametric Analyses
Volume 6: Energy, 2017Co-Authors: Lingen Chen, Bo Yang, Huijun Feng, Zemin DingAbstract:A variable-temperature Heat reservoir irreversible intercooling regeneRated Brayton combined Heat and power (CHP) plant model is set up in this paper. The model considers the Heat transfer losses in all the Heat exchangers, the working substance pressure drop loss in the piping, and the expansion and compression losses in turbine and compressor. Exergy output Rate and exergy efficiency are considered as the research targets, and their analytical formulae are obtained. The optimal performances are gotten by optimizing the intercooled pressure ratio and total pressure ratio. The influences of some important parameters on the performances are studied in detail. Besides, the relation of exergy output Rate versus exergy efficiency is investigated, and the curve is loop-shaped one. The results indicate that optimum Heat Capacity Rate matching between the Heat reservoir and working substance, and optimum Heat consumer required temperature exist respectively, which geneRate double-maximal exergy output Rate and double-maximal exergy efficiency, respectively. The Heat conductance allocation optimization of all the Heat exchangers will be carried out in Part 2 of this paper.
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exergetic efficiency optimization for an irreversible Heat pump working on reversed brayton cycle
Pramana, 2010Co-Authors: Yuehong Bi, Lingen ChenAbstract:This paper deals with the performance analysis and optimization for irreversible Heat pumps working on reversed Brayton cycle with constant-temperature Heat reservoirs by taking exergetic efficiency as the optimization objective combining exergy concept with finite-time thermodynamics (FTT). Exergetic efficiency is defined as the ratio of Rate of exergy output to Rate of exergy input of the system. The irreversibilities considered in the system include Heat resistance losses in the hot- and cold-side Heat exchangers and non-isentropic losses in the compression and expansion processes. The analytical formulas of the Heating load, coefficient of performance (COP) and exergetic efficiency for the Heat pumps are derived. The results are compared with those obtained for the traditional Heating load and coefficient of performance objectives. The influences of the pressure ratio of the compressor, the allocation of Heat exchanger inventory, the temperature ratio of two reservoirs, the effectiveness of the hot- and cold-side Heat exchangers and regenerator, the efficiencies of the compressor and expander, the ratio of hot-side Heat reservoir temperature to ambient temperature, the total Heat exchanger inventory, and the Heat Capacity Rate of the working fluid on the exergetic efficiency of the Heat pumps are analysed by numerical calculations. The results show that the exergetic efficiency optimization is an important and effective criterion for the evaluation of an irreversible Heat pump working on reversed Brayton cycle.
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Ecological, exergetic efficiency and Heating load optimizations for irreversible variable-temperature Heat reservoir simple air Heat pump cycles
Indian Journal of Pure & Applied Physics, 2009Co-Authors: Yuehong Bi, Lingen ChenAbstract:Thermodynamic optimization of an irreversible air Heat pump with variable-temperature Heat reservoirs and hot- and cold-side counter-flow Heat exchangers has been studied. The expressions of the Heating load, the exergetic efficiency and the ecological function of the Heat pump cycle are derived. Performance comparisons among exergetic efficiency optimization, ecological optimization and traditional Heating load optimization objectives are done. The effect of the pressure ratio of the compressor, the allocation of Heat exchanger inventory and the Heat Capacity Rate matching between the working fluid and the Heat reservoirs on the optimal performance of the cycle has been investigated by detailed numerical examples. When the performance optimization of the cycle is carried out by selecting the pressure ratio, three optimization objectives give simultaneously attention to the coefficient of performance (COP). The pressure ratio should be the one that is little bigger than the optimum pressure ratio corresponding to maximum COP, however, the results of three optimization objectives are consistent by optimizing the allocation of Heat exchanger inventory and optimizing the Heat Capacity Rate matching between the working fluid and the Heat reservoirs. The optimum allocations of Heat conductance are close to each other, and they are all less than 0.5. The results may provide guidelines for the design and optimization of practical air Heat pump plants.
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Ecological, exergetic efficiency and Heating load optimizations for endoreversible variable-temperature Heat reservoir simple air Heat pump cycles
International Journal of Low-carbon Technologies, 2009Co-Authors: Yuehong Bi, Lingen ChenAbstract:This paper presents thermodynamic optimization of an endoreversible air Heat pump with variable-temperature Heat reservoirs and hot- and cold-side counter-flow Heat exchangers. The expressions of the Heating load, the exergetic efficiency and the ecological function of the Heat pump cycle are derived. Performance comparisons among exergetic efficiency optimization objective, ecological optimization objective and traditional Heating load optimization objective are performed. The influences of the pressure ratio of the compressor, the allocation of Heat exchanger inventory and the Heat Capacity Rate matching between the working fluid and the Heat reservoirs on the optimal performance of the cycle are investigated by detailed numerical examples. When the performance optimization of the cycle is carried out by selecting the pressure ratio, three optimization objectives give different results; however, the results of three optimization objectives are consistent by optimizing the allocation of Heat exchanger inventory and optimizing the Heat Capacity Rate matching between the working fluid and the Heat reservoirs. The results may provide guidelines for the design and optimization of practical air Heat pump plants. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.
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Heating load, Heating load density and COP optimisations for an endoreversible variable temperature Heat reservoir air Heat pump
Journal of The Energy Institute, 2009Co-Authors: Y. H. Bi, Lingen ChenAbstract:AbstractThe performance optimisation has been studied for an endoreversible air Heat pump with variable temperature Heat reservoirs by taking Heating load, coefficient of performance (COP) and Heating load density, i.e. the ratio of Heating load to the maximum specific volume in the cycle, as the optimisation objectives in this paper. The analytical relations of the Heating load, the COP and Heating load density are derived. The effects of pressure ratio, the effectiveness of the Heat exchangers and the inlet temperature ratio of the Heat reservoirs on the Heating load, the COP and the Heating load density are analysed. The cycle performance optimisations are performed by searching the optimum distribution of Heat conductance of the hot and cold side Heat exchangers for fixed total Heat exchanger inventory and the optimum Heat Capacity Rate matching between the working fluid and the Heat reservoirs. The air Heat pump plant design with Heat loading density optimisation leads to a smaller size including the...
Ping Yuan - One of the best experts on this subject based on the ideXlab platform.
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Effect of inlet flow maldistribution on the thermal performance of a three-fluid crossflow Heat exchanger
International Journal of Heat and Mass Transfer, 2003Co-Authors: Ping YuanAbstract:Abstract This study investigates the effect of flow maldistribution on the thermal performance of a three-fluid crossflow Heat exchanger by the numerical method. In the inlets of three fluid streams, this study considers four modes of flow nonuniformity arrangement by using three flow maldistribution models. According to the results of temperature fields, effectiveness and deterioration factor, this study discusses the deterioration or promotion due to the flow maldistribution in the Heat exchanger. The results indicate that there is a best one in choice between the four maldistribution modes and the best flow maldistribution mode promotes the thermal performance of a three-fluid crossflow Heat exchanger when NTU and Heat Capacity Rate ratios are large.
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The comparison of longitudinal wall conduction effect on the crossflow Heat exchangers including three fluid streams with different arrangements
Applied Thermal Engineering, 2001Co-Authors: Ping YuanAbstract:This study investigates the effect of longitudinal wall conduction on a crossflow Heat exchanger including three fluid streams with three different arrangements. By using numerical method, this study calculates the exit mean temperature of each fluid stream and then computes the deterioration factor of each fluid stream in each arrangement. The results indicate that the effect of longitudinal wall conduction for fluid stream 3 in first arrangement is more severe than that in second arrangement when the Heat Capacity Rate ratio of fluid stream 1 is same to that of fluid stream 3. The deterioration factor of fluid stream 2 is affected slightly by the change of inlet temperature of fluid stream 3 in first and second arrangements. Besides, the longitudinal wall conduction strongly deterioRates the thermal performance of Heat exchangers including three fluid streams at lower Heat Capacity Rate ratios.
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Entropy generation on a three-gas crossflow Heat exchanger with longitudinal wall conduction
International Communications in Heat and Mass Transfer, 2001Co-Authors: Ping YuanAbstract:This study investigates the entropy generation in a crossflow Heat exchanger including three gas streams and the effect of longitudinal wall conduction on the entropy generation. Using the numerical method, this study calculates the exit mean temperature of each stream, and then computes the number of entropy generation units. The results indicate that the entropy generation increases with the decrease of inlet temperature of gas stream 3 and the decrease of inlet temperature ratio of gas streams 1 to 2. In addition, the results show that the longitudinal wall conduction raises the entropy generation and that this raising increases with increasing NTU when Heat Capacity Rate ratio of stream 1 is 0.5.
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THE EFFECT OF LONGITUDINAL WALL CONDUCTION IN A THREE-FLUID CROSSFLOW Heat EXCHANGER
Numerical Heat Transfer Part A-applications, 1998Co-Authors: Ping YuanAbstract:Abstract Because of the effect of longitudinal wall conduction on the thermal performance in a direct transfer-type, single-pass, three-fluid crossflow Heat exchanger, the exit mean temperatures and the deterioration factors in each fluid are calculated by the numerical method. Unit construction of the three-fluid crossflow Heat exchanger is that fluid 2 is sandwiched between fluid I and fluid 3. The results of deterioration factor versus number of transfer units and the inlet temperature of fluid 3 are explored to demonstRate the influences of different Heat Capacity Rate ratios, Heat transfer resistance ratios, and longitudinal wall conduction ratios
Jianlin Yu - One of the best experts on this subject based on the ideXlab platform.
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Optimization of Heat sink of thermoelectric cooler using entropy generation analysis
International Journal of Thermal Sciences, 2017Co-Authors: Jianlin YuAbstract:Abstract In the present study, an optimization model is developed for a thermoelectric cooler (TEC) based on the entropy generation minimization method. In the model, the total entropy generation Rate, the entropy generation number and the exergetic efficiency are proposed as optimization objective functions, respectively, while the number of transfer units of the Heat sink is considered as a constraint. The Heat Capacity Rate of cooling fluid in the Heat sink is optimized under other given conditions. The results show that a minimum total entropy generation Rate and a minimum entropy generation number can be achieved by optimally selecting the Heat Capacity Rate of the cooling fluid. In addition, the minimum total entropy generation Rate and corresponding optimal Heat Capacity Rate of the cooling fluid are both dominated by the number of transfer units and the electrical current. Furthermore, the effects of the Heat Capacity Rate of cooling fluid and the electric current in terms of the exergetic efficiency are also evaluated.
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Optimization of Heat sink configuration for thermoelectric cooling system based on entropy generation analysis
International Journal of Heat and Mass Transfer, 2013Co-Authors: Xiao Wang, Jianlin Yu, Ming MaAbstract:Abstract This paper develops a generalized theoretical model for studying the optimum configuration of a thermoelectric cooling (TEC) system by applying entropy generation analysis method. A dimensionless entropy generation number based on thermal conductance is also proposed to evaluate the external irreversibilities in the TEC system. Based on the model, the optimum configuration analyses of a TEC system are performed. Obtained analysis results indicate that the minimum entropy generation and the maximum coefficient of performance (COP) can be obtained by properly dividing the finite total thermal conductance into the hot side and the cold side Heat exchanger. Furthermore, the effects of the total thermal conductance and the Heat Capacity Rate of the cooling fluid on the irreversibilities under the conditions of the maximum COP and cooling Capacity are also investigated in detail. The present study aims to provide a further insight of the TEC system optimization.
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design optimization of thermoelectric cooling systems for applications in electronic devices
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Yuanyuan Zhou, Jianlin YuAbstract:Abstract This paper presents a generalized theoretical model for the optimization of a thermoelectric cooling (TEC) system, in which the thermal conductances from the hot and cold sides of the system are taken into account. Detailed analyses of the optimal allocation of the finite thermal conductance between the cold-side and hot-side Heat exchangers of the TEC system are conducted by considering the constraint of the total thermal conductance. The analysis results show that the maximum coefficient of performance (COP) and the maximum cooling Capacity of the TEC system can be obtained when the finite total thermal conductance is optimally allocated. Furthermore, the effects of the total thermal conductance and the Heat Capacity Rate of the cooling fluid on the performance of the TEC system and the optimal thermal conductance allocation ratio are also examined.
J M Corberan - One of the best experts on this subject based on the ideXlab platform.
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exergy analysis on a Heat pump working between a Heat sink and a Heat source of finite Heat Capacity Rate
International Journal of Refrigeration-revue Internationale Du Froid, 2019Co-Authors: Miquel Pitarch, Estefania Hervasblasco, Emilio Navarroperis, J M CorberanAbstract:Abstract The optimum performance of a pure subcritical refrigeration cycle depends significantly on the temperature lift of the Heat source and sink. Therefore, the maximization of the system efficiency has to be linked to them. This paper shows an exergy analysis of each Heat pump component (condenser, evaporator, expansion valve and compressor) considering that the Heat source and sink are not at constant temperature. The performed study shows the components with more possibilities for improvement. Based on this analysis, the optimization of cycle parameters like subcooling and superHeat as a function of the external conditions have been done. In addition, this work has demonstRated that the components having a higher influence in the system irreversibility's depends significantly on the temperature lift of the secondary fluids. Finally, the obtained results show potentials improvements of the efficiency up to 23% if the system is able to opeRate in the optimal subcooling and superHeat.
Yuehong Bi - One of the best experts on this subject based on the ideXlab platform.
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exergetic efficiency optimization for an irreversible Heat pump working on reversed brayton cycle
Pramana, 2010Co-Authors: Yuehong Bi, Lingen ChenAbstract:This paper deals with the performance analysis and optimization for irreversible Heat pumps working on reversed Brayton cycle with constant-temperature Heat reservoirs by taking exergetic efficiency as the optimization objective combining exergy concept with finite-time thermodynamics (FTT). Exergetic efficiency is defined as the ratio of Rate of exergy output to Rate of exergy input of the system. The irreversibilities considered in the system include Heat resistance losses in the hot- and cold-side Heat exchangers and non-isentropic losses in the compression and expansion processes. The analytical formulas of the Heating load, coefficient of performance (COP) and exergetic efficiency for the Heat pumps are derived. The results are compared with those obtained for the traditional Heating load and coefficient of performance objectives. The influences of the pressure ratio of the compressor, the allocation of Heat exchanger inventory, the temperature ratio of two reservoirs, the effectiveness of the hot- and cold-side Heat exchangers and regenerator, the efficiencies of the compressor and expander, the ratio of hot-side Heat reservoir temperature to ambient temperature, the total Heat exchanger inventory, and the Heat Capacity Rate of the working fluid on the exergetic efficiency of the Heat pumps are analysed by numerical calculations. The results show that the exergetic efficiency optimization is an important and effective criterion for the evaluation of an irreversible Heat pump working on reversed Brayton cycle.
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Ecological, exergetic efficiency and Heating load optimizations for irreversible variable-temperature Heat reservoir simple air Heat pump cycles
Indian Journal of Pure & Applied Physics, 2009Co-Authors: Yuehong Bi, Lingen ChenAbstract:Thermodynamic optimization of an irreversible air Heat pump with variable-temperature Heat reservoirs and hot- and cold-side counter-flow Heat exchangers has been studied. The expressions of the Heating load, the exergetic efficiency and the ecological function of the Heat pump cycle are derived. Performance comparisons among exergetic efficiency optimization, ecological optimization and traditional Heating load optimization objectives are done. The effect of the pressure ratio of the compressor, the allocation of Heat exchanger inventory and the Heat Capacity Rate matching between the working fluid and the Heat reservoirs on the optimal performance of the cycle has been investigated by detailed numerical examples. When the performance optimization of the cycle is carried out by selecting the pressure ratio, three optimization objectives give simultaneously attention to the coefficient of performance (COP). The pressure ratio should be the one that is little bigger than the optimum pressure ratio corresponding to maximum COP, however, the results of three optimization objectives are consistent by optimizing the allocation of Heat exchanger inventory and optimizing the Heat Capacity Rate matching between the working fluid and the Heat reservoirs. The optimum allocations of Heat conductance are close to each other, and they are all less than 0.5. The results may provide guidelines for the design and optimization of practical air Heat pump plants.
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Ecological, exergetic efficiency and Heating load optimizations for endoreversible variable-temperature Heat reservoir simple air Heat pump cycles
International Journal of Low-carbon Technologies, 2009Co-Authors: Yuehong Bi, Lingen ChenAbstract:This paper presents thermodynamic optimization of an endoreversible air Heat pump with variable-temperature Heat reservoirs and hot- and cold-side counter-flow Heat exchangers. The expressions of the Heating load, the exergetic efficiency and the ecological function of the Heat pump cycle are derived. Performance comparisons among exergetic efficiency optimization objective, ecological optimization objective and traditional Heating load optimization objective are performed. The influences of the pressure ratio of the compressor, the allocation of Heat exchanger inventory and the Heat Capacity Rate matching between the working fluid and the Heat reservoirs on the optimal performance of the cycle are investigated by detailed numerical examples. When the performance optimization of the cycle is carried out by selecting the pressure ratio, three optimization objectives give different results; however, the results of three optimization objectives are consistent by optimizing the allocation of Heat exchanger inventory and optimizing the Heat Capacity Rate matching between the working fluid and the Heat reservoirs. The results may provide guidelines for the design and optimization of practical air Heat pump plants. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.
