Unravelling entropic features of La(Fe,Si)13Hy-based refrigerant inside an active magnetic regenerative bed component via in-situ magnetic observations

To clarify how magnetocaloric properties of a magnetic refrigerant (MR) are reflected in the magnetic refrigeration thermodynamic cycle, the AC susceptibility χac of the La(Fe,Si)13Hy-based magnetic refrigerant (MR) that makes up the random-packed bed component of an active magnetic regenerative module was measured during heat cycle motion. The variation in χac was projected onto entropy–temperature (S–T) diagrams to correlate the local MC properties of the MR and the heat-pump action of the module. A maximum temperature span (ΔTspan) appears when ΔTspan adaptively covers the phase-transition zone of the S–T diagrams. The adiabaticity against the field change was broken when the MR exhibited a steeply S-T change. The Influence of the heat load on the local cycle attributed a collapse of ΔTspan to the expansion of unworkable paramagnetic bed segments. [Display omitted]