A 2D hybrid model of the fluid flow and heat transfer in a reciprocating active magnetic regenerator

This paper evaluates the thermal behavior of a magnetic-Brayton-based parallel plate reciprocating active magnetic regenerator (AMR). A time-dependent, 2D model of the fluid flow and the coupled heat transfer between the working fluid and the solid refrigerant (gadolinium) is proposed. A hybrid calculation method which consists of an analytical solution for the flow and a numerical solution for the thermal field has been adopted. Results for the cooling capacity as a function of the temperature span and mass flow rate agree well with trends observed in experimental data and other theoretical models available in the literature. The volume of fluid displaced through the channels during the isofield processes influences significantly the AMR performance. For a cycle frequency of 1 Hz, the cycle-averaged cooling capacity reaches a maximum when the utilization factor is 0.1 and the displaced fluid volume equals 62% of the fluid volume of the AMR.

► Analytical model of fluid flow in parallel plate active magnetic regenerator (AMR).
► Numerical analysis of conjugate fluid-solid heat transfer in parallel plate AMR.
► Hybrid model predicts effect of frequency on the local Nusselt number.
► New evaluation parameter, the fluid volume ratio, is introduced.
► Average cooling capacity is maximum when the fluid volume ratio equals 0.62.