Enhancing the temperature span of thermal switch-based solid state magnetic refrigerators with field sweeping

Magnetocaloric refrigeration has been pointed out as the most promising alternative to the ubiquitous vapor-compression refrigeration technology due to its high coefficient of performance. Nevertheless, the use of hydraulic components in current devices is, among other reasons, hindering their commercial widespread. Solid state thermally switchable components are alternatives to the use of fluids. Since current developed structures are not ideal, the refrigerator operation design must be optimized to reduce their strict requirements. Active magnetic regeneration in fully solid state systems has been recently shown to be possible by moving the magnetic field gradually at constant speed, i.e., in several isochronal steps. Here, we investigate the implications of different operating modes on the temperature span, where the motion of the magnetic field includes acceleration and deceleration. When the magnetic field is either applied in a single step or from the cold to the hot reservoirs with linear or decelerated motion and is removed with acceleration motion from the hot to the cold reservoirs, the resulted temperature span increases up to 20%. The implications of each operating mode on the optimum frequency is discussed.