Integrated design of active magnetic regenerators and heat exchangers for magnetic refrigerators.

Refrigeration systems, including the magnetic ones, require heat exchangers for their operation. Curiously, most of research studies in magnetic cooling do not consider these components in their analyses. This work presents an evaluation of the influence of the heat exchangers on the thermodynamic performance of an active magnetic regenerator. A model based on the ε-NTU method is proposed to integrate the heat exchangers and the regenerator. Commercially available fan assisted tube-fin heat exchangers were selected for the evaluation of the most suitable options for application in a compact magnetic refrigerator. Numerical simulation showed that the influence of the heat exchanger on the regenerator performance can be represented by the product of the heat exchanger effectiveness and the ratio of the thermal capacity rates of the streams. For a system temperature span of 20 K, the best heat exchanger/fan assembly resulted in a reduction of 36.1% in the cooling capacity and an increase of 48.3% in the active magnetic regenerator temperature span.