Performance assessment of a triangular microchannel active magnetic regenerator

Abstract

The manufacturing process and mechanical instability of high performance magnetocaloric materials hamper the implementation of novel geometries for active magnetic regenerators. In this work, La(Fe,Si,Mn)13Hy is shaped into a regenerator with triangular microchannels with a hydraulic diameter of 200–300 μm using a process that results in a highly stable structure. The regenerator is characterized with regards to heat transfer, hydraulic resistance, magnetocaloric cooling and mechanical stability. The cooling performance is similar to conventional packed bed AMRs but with a significantly lower flow resistance. The chemical and mechanical stabilities are validated by comparisons of heat transfer effectiveness, pressure drop and magnetocaloric properties of the regenerator before and after long-term testing. The machining accuracy of microchannels with a brittle magnetocaloric material is therefore qualified. According to the performance evaluation criterion, this regenerator has a good potential for maximizing the operational coefficient of performance, with an estimated 42% improvement of COP in a specific magnetic refrigerator.