Magnetic refrigeration: Single and multimaterial active magnetic regenerator experiments

An investigation of active magnetic regenerators (AMRs) has been performed near room temperature using helium as a heat transfer fluid and a magnetic field of 2 T. To evaluate the impact of the operating conditions, the performance of two reciprocating 90 g gadolinium packed bed regenerators was mapped as a function of the fluid flux and cycle frequency. In addition, two multilayer regenerators of similar mass and dimensions, composed of a layer of gadolinium and a layer of a gadolinium-terbium alloy, were tested and compared to the performance of the Gd-only regenerators. The multilayer regenerators produced a larger temperature span and cooling power compared to the single material regenerators of equivalent mass and geometry (temperature spans of about 20 and 16 K, respectively). Theses results validate the concept of a multilayer AMR, provide useful data for magnetic refrigerator design, and provide better understanding of active magnetic refrigeration. (C) 2004 American Institute of Physics.