The influence of demagnetizing effects on the performance of active magnetic regenerators

摘要

Active magnetic regenerators (AMR) comprise an involved, multi-physics problem including heat transfer, fluid flow, magnetocaloric properties, and demagnetizing fields. In this paper a method is developed that combines previously published models that simulate a parallel-plate AMR and the magnetostatics of a stack of parallel plates, respectively. Such a coupling is non-trivial due to the significant increase in computational time, and a simplified scheme is thus developed and validated resulting in little extra computational effort needed. A range of geometrical and operating parameters are varied, and the results show that not only do demagnetizing effects have a significant impact on the AMR performance, but the magnitude of the effect is very sensitive to a range of parameters such as stack geometry (number of plates, dimensions of the plates and flow channels, and overall dimensions of the stack), orientation of the applied field, and the operating conditions of the AMR (such as thermal utilization).