Magnetic heat pumps: An overview of design principles and challenges

Active magnetic regeneration is one of the most promising alternative technologies for the development of heat pumps and cooling systems for applications around room temperature. In the open literature, numerous works can be found in which much effort has been put on the development of magnetocaloric materials, magnetic circuits and prototypes. In this article, the authors discuss some of the main challenges encountered in the literature and how design choices impact cooling power and work requirements from a system engineering perspective. First, based on a generic schematic representation of a magnetocaloric heat pump, or refrigerator, various problems and challenges found in the current state of the art are pointed out and discussed. Second, different design principles for magnetic heat pumps are examined. As a means to improving performance, an extended design/optimization methodology is proposed based on entropy generation minimization with performance criteria. Finally, some initial optimization results are presented and discussed.