Exergetic efficiency optimization for real regenerated air refrigerators

On the basis of the exergetic analysis, the performance analysis and optimization is carried out for irreversible regenerated air refrigerators by taking exergetic efficiency as the optimization objective using thermodynamic optimization in this paper. Exergetic efficiency is defined as the ratio of rate of exergy output to rate of exergy input of the system. The analytical formulas of the cooling load, coefficient of performance (COP) and exergetic efficiency for the refrigerators are derived. The influences of the pressure ratio of the compressor, the allocation of heat exchanger inventory, the temperature ratio of two reservoirs, the effectivenesses of the hot- and cold- side heat exchangers and regenerator, the efficiencies of the compressor and expander, the pressure recovery coefficient, and the total heat exchanger inventory on the exergetic efficiency of the refrigerators are investigated by detailed numerical examples. The results show that the exergetic efficiency optimization is an important and effective criterion for the evaluation of irreversible regenerated air refrigerators.