Thermodynamic Performance Characteristics of a Regenerative Brayton Refrigeration Cycle Using Gd0.45Tb0.55 and Gd as the Working Substance

Based on experimental characteristics of the iso-field heat capacity of the working substances Gd0.45Tb0.55and Gd, the magnetic entropy change with temperature is calculated. The regenerative Brayton refrigeration cycles employing these materials as the working substances are established. By means of thermodynamic analysis and numerical calculation, the effects of the non-perfect regeneration on the performance characteristics of the refrigeration cycles are revealed. Furthermore, the cyclic performances employing Gd0.45Tb0.55and Gd as the working substances are evaluated and compared. The results obtained may provide some useful information for the optimal design of the room temperature magnetic refrigerators.

Performance Analysis of the Regenerative Brayton Refrigeration Cycle Using Gd0.94Er0.06 as the Working Substance

Based on the experimental data of entropy change varying with temperature, the regenerative Brayton refrigeration cycle using Gd0.94Er0.06 as the working substance is set up for magnetic field changes with 0-1T and 0-2T. By using thermodynamic analysis method, some parameters such as the non-perfect regeneration, net cooling quantity, coefficient of performance (COP), and so on, are analyzed and calculated. The effects of temperature of the heat reservoir, regeneration and external magnetic field are also discussed. The results obtained in the present paper show that the refrigeration cycle operating in TC=T0, TH= T0+7K and 0-2T magnetic field change has not only maximum cooling quantity but also maximum COP in all the established magnetic refrigeration cycles, and can provide some new guide for the optimal design of real room-temperature magnetic refrigerators.