Influence of the heat exchangers thermal conductance on the thermodynamic performance of a magnetic refrigerator.

In the majority of the magnetic refrigeration devices developed so far, the thermal load is provided by an electrical heater in direct contact with the working fluid in the cold heat exchanger. This is acceptable in laboratory devices, but does not represent the real thermal interactions taking place in the heat exchanger in contact with the refrigerated environment (e.g., the air inside the cabinet of the refrigerator). In this work, the influence of the thermal conductances of the heat exchangers on the thermodynamic performance of a magnetic refrigerator has been analyzed. A mathematical model based on the 𝜀-NTU method was developed and implemented in an AMR numerical model. The results reveal a significant deterioration of the system performance as the thermal conductances are decreased. The system performance is more sensitive to the overall thermal conductance of the hot-side heat exchanger. This should be considered in the design of actual AMR operating with real heat exchangers.