Performance characteristics of magnetic Brayton refrigeration cycles using Gd, Gd0.74Tb0.26 and (Gd3.5Tb1.5)Si4 as the working substance

Based on the experimental characteristics of the iso-field heat capacity changing with temperature for the room-temperature magnetic refrigeration materials Gd, Gd0.74Tb0.26, and (Gd3.5Tb1.5)Si4, the corresponding entropy versus temperature curves are calculated and presented, the regenerative magnetic Brayton refrigeration cycles, using these magnetic materials as the working substances, are established. The non-perfect regenerative heat quantity, net cooling quantity, released heat quantity, coefficient of performance (COP) and other performance parameters of these magnetic Brayton refrigeration cycles are analyzed and calculated. Furthermore, the performance characteristics of the Brayton refrigeration cycles employing Gd, Gd0.74Tb0.26, and (Gd3.5Tb1.5)Si4 as the working substance are evaluated and compared, the influence of non-perfect regenerative heat on the performance characteristics of these magnetic Brayton refrigeration cycles is revealed.

► Based on experimental data, magnetic Brayton refrigeration cycles are built.
► Gd, Gd0.74Tb0.26 and (Gd3.5Tb1.5)Si4 are the working substances.
► Different position to T0 and temperature span cycles are analyzed and compared.
► Optimal values are explained with mathematic proofs.
► Cycles placed below T0 are exhibiting best thermodynamics performance.