ANALYSIS OF TERBIUM THERMODYNAMIC CHARACTERISTICS FOR MAGNETIC HEAT-PUMP APPLICATIONS

Based on molecular field theory, including the effect of the field-dependent nature of Neel temperature, the entropy, and the magnetocaloric effect in terbium (Tb) have been calculated with the external field between 0 and 7 T (Tesla). The calculated results are compared with the existing experimental measurements. The maximum magnetocaloric temperature change (DELTAT) is approximately 14 K near the zero-field Neel temperature (230 K) for an external field at 7 T field. This relatively large magnetocaloric effect indicates that Th could be an attractive candidate for magnetic heat pump application. The results are then used to study the performance of heat pumps for the Carnot cycle, the constant field cycle, and the ideal regenerative cycle. The performances of these three cycles are discussed and compared.