The performance of an irreversible Carnot refrigeration cycle

The concept of finite-time thermodynamics is employed to investigate the optimal heat absorbing rate for a refrigeration cycle. In this analysis, the heat transfer between the system (internal) fluid and cooling (external) fluid takes place at the actual heat exchanger, which has finite-size heat transfer area and realistic heat transfer effectiveness. The optimal rate of refrigeration is calculated and expressed in terms of the coefficient of performance (COP), the time ratio of refrigeration cycle to heat transfer processes, and the effectiveness of heat exchanger. The COP obtained in this study is more realistic than the reversible cycle and can thus be considered as the 'benchmark' value for a practical refrigeration cycle.