Interrelationship between flow profiles and the magnetic waveform and their influence on the performance of first-order active magnetic regenerators

Abstract

Magnetic refrigeration is one of the most prominent unconventional near-room-temperature cooling technologies. However, some factors currently prevent it from reaching commercial levels, such as the high cost and relatively low energetic performance of magnetic materials used in the Active Magnetic Regenerator (AMR) and Magnetic Circuit (MC). As a result, an essential task in designing such systems is to extract the best possible performance by finding an optimal operating condition. In this paper, an experimentally validated one-dimensional two-temperature AMR model analyses the relationship between the time-dependent flow and magnetic field waveforms (profiles) and quantifies their mutual influences to maximise the cooling capacity of a La–Fe–Si-based AMR. The results show that, for all cases, the cooling capacity reaches a peak when both profiles are considered synchronised and have the same high and low periods. When some sort of phase lag is present, the drop in cooling capacity is smaller if the fluid blow is delayed with respect to the magnetic profile. In the case of trapezoidal waveforms, the cooling capacity increases with the decrease of the ramp periods, i.e., as the flow approaches a square wave.