Thermal performance mapping of microchannel active magnetic regenerator under oscillatory fluid flows.

The paper describes a computational model of the transient conjugated conductive heat transfer in magnetocaloric material (MCM) microchannel wall and convective heat transfer in fluid flow in channels. The model is solved using Ansys Fluent. The temperature span, transient variation of Nusselt number (Nu) and effect of the ratio of channel spacing to diameter (porosity) are examined. Heat transfer enhancement and AMR dimension optimization are presented. The present study focused on the mapping the thermal response of active magnetic regenerator made of different geometric configurations, materials and exposed to different heat transfer fluids. For microchannel regenerator, the ratio б/d which defines the porosity was seen to have significant effect of the achievable temperature span. The optimum performance was seen to be for a Biot number (Bi) values of below 0.1. For heat transfer fluids, liquid metals Galinstan and Sodium-Potassium (NaK) yielded higher temperature spans as compared to the water, however, their corresponding pumping power requirements were also higher.