A GdxHo1−x-based composite and its performance characteristics in a regenerative Ericsson refrigeration cycle

Based on the molecular field theory, de Gennes factor model, and numerical calculation method, the magnetic entropy change and Curie temperature of GdxHo1−x alloys are studied, where x = 0.80, 0.91, and 1. The composite magnetic material consists of Gd0.80Ho0.20, Gd0.91Ho0.09, and Gd, according to the definite mass ratios y1, y2 and y3. The calculation results show that there exist optimal mass ratios y1opt, y2opt, and y3opt and their values depend on the applied magnetic field μ0H1. When μ0H1 = 2 T, y1opt, y2opt, and y3opt are equal to 0.24, 0.17, and 0.59, respectively. It is found that the total magnetic entropy change of the composite magnetic material 0.24Gd0.80Ho0.20⋅0.17Gd0.91Ho0.09⋅0.59Gd under 2 T applied magnetic field change is close to a constant in the region between 265 K and 293 K. Furthermore, the regenerative Ericsson refrigeration cycle using the composite magnetic material as the working substance is put forward and its cyclic performances including the net cooling quantity Qnet, coefficient of performance (COP), etc. are analyzed. The results obtained show that for the regenerative Ericsson refrigeration cycle using the composite magnetic material as the working substance, there are not only a large temperature span (28 K) but also a large net cooling quantity (1008 J/kg under 2 T applied magnetic field) and a large COP (9.01), which are, respectively, larger than those of regenerative Ericsson refrigeration cycles using Gd0.80Ho0.20, Gd0.91Ho0.09 or Gd. Moreover, the effect of the applied magnetic field on the cyclic performance of the regenerative Ericsson refrigeration using the composite magnetic material as the working substance is investigated.