Geometrical optimization of packed-bed and parallel-plate active magnetic regenerators

The paper presents the numerical optimization of a packed-bed and a parallel-plate AMR with gadolinium as the magnetocaloric material. The diameter of the spheres and the length of the packed-bed AMR, and the plate thickness, the spacing between the plates (porosity) and the length of the parallel-plate AMR, were varied and optimized. The results reveal that for the considered conditions the optimum length of the packed-bed AMR should be 20 mm or less at higher operating frequency (3 Hz) and 40 mm at lower operating frequency (0.5 Hz) and the corresponding optimum sphere diameter should be between 0.07 mm (with regard to the cooling load) and 0.17 mm (with regard to the COP). The parallel-plate AMR should consist of plates that are as thin as possible, with a spacing between the plates of 0.035 mm (with regard to the cooling load) and 0.075 mm (with regard to the COP).