Predicting the Performance of an Active Magnetic Regenerator Refrigerator Used for Space Cooling and Refrigeration

Active magnetic regenerative refrigeration (AMRR) systems represent an environmentally attractive refrigeration alternative that does not use a fluorocarbon working fluid. Recently, families of magnetocaloric material alloys with adjustable Curie temperatures have been developed. Using these materials, it is possible to construct a layered regenerator bed that can achieve a high magnetocaloric effect across its entire operating temperature range. This paper describes a numerical model capable of predicting the practical limits of performance of this technology applied to space-conditioning and refrigeration applications. The model treats the regenerator bed as a one-dimensional matrix of magnetic material with a spatial variation in Curie temperature and, therefore, magnetic properties. The matrix is subjected to a spatially and temporally varying magnetic field and fluid mass flow rate. The numerical model is solved using a fully implicit discretization of the governing energy equations. The nonlinear aspects of the governing equations (e.g., fluid and magnetic property variations) are handled using a relaxation technique. Modeling results are presented that illustrate how an AMRR system can be optimized for a particular operating condition. The performance of layered and nonlayered AMRRs are compared to current vapor compression technology for space-conditioning and refrigeration applications.