Heat transfer figures of merit for mapping passive regenerator performance to active regenerator cooling power

This study reports specific heat transfer figures of merit for thermal regenerators and applications using the passive characterization, which can rapidly predict the cooling capacity of active magnetic regenerators (AMRs) in magnetic refrigeration. We expand the expression for the thermal effectiveness in terms of the individual contributions of heat storage and parasitic losses, using one-dimensional energy equations and mathematical estimations. Furthermore, a quantitative expression correlating the heat transfer effectiveness and cooling capacity provides a metric for the characterization of AMRs having new porous geometries. We found that the solid heat storage term of the effectiveness has a clearer impact on both the conjugate heat transfer and cooling capacity of AMRs than the entire effectiveness does.