Theoretical optimization of a regenerated air refrigerator

The performance analysis and optimization of a regenerated air refrigerator is carried out by taking the cooling load density, i.e. the ratio of cooling load to the maximum specific volume in the cycle, as the optimization objective using finite-time thermodynamics or entropy generation minimization in this paper. Analytical relationships between cooling load density and pressure ratio, as well as between coefficient of performance (COP) and pressure ratio are derived. The irreversibilities considered in the analysis include the heat transfer losses in the hot- and cold-side heat exchangers and the regenerator, the non-isentropic compression and expansion losses in the compressor and expander, and the pressure drop losses in the piping. The comparison of the cycle performances under maximum cooling load density and maximum cooling load conditions is performed. The optimal performance characteristics of the cycle are obtained by optimizing the pressure ratio of the compressor, and searching the optimum distribution of heat conductances of the hot- and cold-side heat exchangers and regenerator for the fixed total heat exchanger inventory. The influences of the effectivenesses of the regenerator as well as the hot- and cold-side heat exchangers, the efficiencies of the expander and the compressor, the pressure recovery coefficient, and the temperature ratio of the heat reservoirs on the cooling load density and COP are examined and shown by numerical examples.

[1]  Fengrui Sun,et al.  Cooling load density characteristics of an endoreversible variable‐temperature heat reservoir air refrigerator , 2002 .

[2]  Fengrui Sun,et al.  Performance of heat-transfer irreversible regenerated Brayton refrigerators , 2001 .

[3]  Fengrui Sun,et al.  Optimum Allocation of Heat Exchanger Inventory of Irreversible Air Refrigeration Cycles , 2002 .

[4]  Lingen Chen,et al.  Performance and optimization criteria for forward and reverse quantum Stirling cycles , 1998 .

[5]  Lingen Chen,et al.  Cooling Load Density Optimization of an Irreversible Simple Brayton Refrigerator , 2002, Open Syst. Inf. Dyn..

[6]  S. Sieniutycz,et al.  Thermodynamic Optimization of Finite-Time Processes , 2000 .

[7]  Fengrui Sun,et al.  Finite-time thermodynamic performance of an isentropic closed regenerated Brayton refrigeration cycle , 1997 .

[8]  Lingen Chen,et al.  Optimal performance coefficient and cooling load relationship of a three-heat-reservoir endoreversible refrigerator , 1997 .

[9]  W. L. Swift,et al.  Progress on the Development of Miniature Turbomachines for Low-Capacity Reverse-Brayton Cryocoolers , 1997 .

[10]  Hasbi Yavuz,et al.  The maximum cooling density of a realistic Stirling refrigerator , 1998 .

[11]  Adrian Bejan,et al.  Power and Refrigeration Plants for Minimum Heat Exchanger Inventory , 1993 .

[12]  Sun Feng-rui,et al.  Cooling Load Density Analysis and Optimization for an Endoreversible Air Refrigerator , 2001 .

[13]  Adrian Bejan,et al.  Theory of heat transfer-irreversible power plants. II: The optimal allocation of heat exchange equipment , 1995 .

[14]  Lingen Chen,et al.  Optimisation of steady flow refrigeration cycles , 1996 .

[15]  A. Bejan,et al.  Entropy Generation Through Heat and Fluid Flow , 1983 .

[16]  Harvey S. Leff,et al.  EER, COP, and the second law efficiency for air conditioners , 1978 .

[17]  A. Bejan.  Theory of heat transfer-irreversible power plants , 1988 .

[18]  Lawrence S. Chen.  Cooling load versus COP characteristics for an irreversible air refrigeration cycle , 1998 .