Comparison on the optimum performances of the irreversible Brayton refrigeration cycles with regeneration and non-regeneration

An irreversible model of the Brayton refrigeration cycles with regeneration and non-regeneration is established in a unified way, in which the irreversibilities resulting from the internal dissipation of the working substance in the adiabatic processes and the finite-rate heat transfer in the regenerative and isobaric processes are taken into account. Expressions for several important performance parameters, such as the cooling load, coefficient of performance (COP) and regeneration, are derived. The optimal performances of a regenerative and a non-regenerative refrigeration cycle are compared quantitatively. The advantages of the two cycle models are expounded, respectively. The optimal region of regeneration is determined. Moreover, some optimally operating parameters of a regenerative Brayton refrigeration cycle, such as the temperatures of the working substance at different state points, pressure ratio, and ratios of the various heat transfer areas to the total heat transfer area, are determined. The optimal relations between these parameters and the COP are presented by a set of characteristic curves. The results obtained may be helpful to the comprehensive understanding for the performance characteristics of the Brayton refrigeration cycles with non-regeneration and regeneration.