From the experimental data of the isofield heat capacity of the MnFe-based magnetocaloric materials, magnetic entropy change versus temperature characteristic curves are obtained by using numerical value calculation procedure. Three kinds of MnFe-based magnetocaloric materials, in which there are all a large magnetocaloric effect, are selected as the constituent materials to establish a novel composite magnetocaloric material, for which keeping large magnetic entropy change over a wide temperature range is desired. By means of thermodynamic analysis and optimal control theory, the molar mass ratios of each constituent material to the composite material are optimally determined for differently applied magnetic fields. The optimum results show that when the applied magnetic field μ₀H″=2 T, the optimum molar mass ratios x_1opt, x_2opt, and x_3opt of Mn_1.24Fe_0.76P_0.75Ge_0.25, Mn_1.2Fe_0.8P_0.75Ge_0.25, and Mn_1.1Fe_0.9P_0.78Ge_0.22 to the composite are equal to 0.44, 0.11, and 0.45, respectively. Furthermore, the regenerative Ericsson refrigeration cycle employing the composite or constituent materials as the working substance is set up. The effects of the non-perfect regeneration on the net cooling quantity, COP, etc. of the refrigeration cycle are analyzed and evaluated. The cycle performances of the composite material are compared with those of the constituent materials. It shows that the net cooling quantity and COP of the composite are much larger than those of any constituent material. The numerical calculation results obtained can provide some reference for the selection of working substances and the optimal parameter design of room temperature magnetic refrigerators.

从MnFe基磁热材料的等场热容量的实验数据，通过使用数值计算程序获得了磁熵变对温度的特性曲线。选择全部具有大的磁热效应的三种MnFe基磁热材料作为构成材料，以建立新型的复合磁热材料，为此期望在宽温度范围内保持大的磁熵变。借助热力学分析和最优控制理论，可以针对不同的施加磁场，最优地确定每种组成材料与复合材料的摩尔质量比。最佳结果表明，当所施加的磁场μ ₀ H“= 2 T，Mn _1.24 Fe _0.76 P _0.75 Ge _0.25，Mn _1.2 Fe _0.8 P _0.75 Ge _0.25和Mn _1.1 Fe _0.9 P _0.78 Ge _0.22的最佳摩尔质量比x _1opt，x _2opt和x _3opt为复合材料分别等于0.44、0.11和0.45。此外，建立了以复合材料或构成材料作为工作物质的爱立信蓄冷循环系统。不良再生对净冷却量COP的影响分析和评估制冷循环等。将复合材料的循环性能与组成材料的循环性能进行比较。结果表明，复合材料的净冷却量和COP远远大于任何组成材料的净冷却量和COP。数值计算结果可为室温电磁制冷机的工作物质选择和最佳参数设计提供参考。