THE INFLUENCE OF HEAT LEAKAGE AND INTERNAL IRREVERSIBILITY ON THE PERFORMANCE OF A QUANTUM SPIN REFRIGERATION CYCLE

Abstract

The cycle model established here, for which the heat leakage and internal irreversibility are considered, consists of two irreversible non-isentropic adiabatic and two isomagnetic field processes. The working substance is composed of many non-interacting spin systems. Based on quantum master equation of an open system in the Heisenberg picture and semi-group approach, the general performance analysis of quantum refrigeration cycle is performed. Expressions for several important performance parameters, such as the cooling rate, coefficient of performance, rate of entropy production and power input, are derived. By using numerical calculations, the cooling rate as a natural optimization goal for a refrigerator is optimized with respect to external magnetic field. The characteristic curves of the cooling rate, rate of entropy production and power input subject to coefficient of performance are plotted. The optimal regions of the cooling rate, coefficient of the performance (COP) and temperatures of the working substance, are determined.