Performance analysis of a quantum heat-pump using spin systems as the working substance

The performance of a quantum-mechanical heat pump using many non-interacting spin-1/2 systems as the working substance and consisting of two isothermal and two isomagnetic field processes is investigated, based on the quantum master equation and semi-group approach. The inherent regenerative losses in the two isomagnetic field processes are calculated and the influence of non-perfect regeneration on the performance of the cycle is analyzed. Expressions for some important performance parameters, such as the coefficient of performance, heating load, power input, and rate of the entropy production, are derived. Several interesting cases are discussed and, especially, the optimal performance of the cycle at high temperature is discussed in detail. Some important characteristic curves of the cycle, such as the heating load versus coefficient of performance curves, the power input versus coefficient of performance curves, the heating load versus power input curves, and so on, are presented. The maximum heating-load and the corresponding coefficient of performance are calculated. Other optimal performances are also analyzed. The results obtained here are further generalized, so that they may be directly used to describe the performance of the quantum heat-pump using spin-J systems as the working substance.