Design and comparison of electro-permanent magnetic field sources for magnetocaloric heat pumps

We present the results of a comprehensive study of the design, numerical analyses and experimental validation of various electro-permanent magnetic structures that can be used in magnetocaloric refrigeration. Most magnetic field sources currently used in conceptual magnetic cooling devices require moving parts, which produce noise, vibrations and require maintenance. Furthermore, the operating frequency of such magnetic structures is relatively low and limited by aspects of the mechanical construction. Unlike any magnetic structure currently used in a magnetocaloric refrigeration device, the presented structure consists of a hybrid assembly of an electromagnet and a permanent magnet. We report on how different configurations of permanent magnets and the windings of electromagnets, including the air gaps, affect the energy efficiency, the input power and the total mass of the magnetic field source. Some guidelines for future research and the development of electro-permanent magnetic field sources for magnetocaloric refrigeration and heat pumps are presented, supported by information on how such structures can enable higher operating frequencies that could increase the compactness of future magnetocaloric devices.