Experimental Study of Active Magnetic Regenerator (AMR) Composed of Spherical GdN

An experimental study of an active magnetic regenerator (AMR) employing GdN was carried out. Spherical GdN material was synthesized by the hot isostatic pressing (HIP) method. The specific heat was measured and the magnetic entropy change ΔS and adiabatic temperature change ΔTad were calculated. The refrigeration with an AMR cycle was tested in the temperature range between 48 and 66 K with the field swinging from 1.2 to 3.7 T at upper side and from 2.0 to 4.0 T at lower side of the regenerator bed filled with GdN spheres. A temperature span, ΔTspan,was found to develop soon after starting the cycle and became more than 4.7 degree in steady state. This temperature span ΔTspan was at least 1.5 times as large as the adiabatic temperature change ΔTad.