Numerical modeling of magnetocaloric gadolinium particle flow: Magnetization nonlinearity governs net magnetocaloric heat

Magnetocaloric particle flow has been proposed as a mechanically simple alternative to solid active magnetic regenerators (AMR), replacing solid beds with a particle flow continuously circulating through a fixed magnetic field. Unlike conventional AMR, which relies on reciprocating regeneration to build and sustain a temperature span, unidirectional circulation lacks an obvious mechanism to continuously establish a thermal gradient along the magnetocaloric material. This raises a fundamental question: can net magnetocaloric heat accumulate over many cycles in a unidirectional circulation to produce a meaningful temperature change? Here, we develop a one-dimensional magnetocaloric hydrodynamic model of a circulating gadolinium particle flow to systematically examine cumulative energy changes under material magnetization, magnetic wall friction, and Kelvin-force-driven transport. By isolating four operating modes, we find that the net magnetocaloric heat does exist, where the intrinsic material magnetization is the only mechanism capable of generating such persistent energy bias (up to 14%). This material-driven asymmetry produces a modest but robust “Curie-point compensation,” a net tendency for magnetocaloric heat to drive the system toward the material's Curie temperature. Conversely, magnetic forces merely redistribute or suppress this bias without generating additional net heat. These results clarify why fixed-field particle flow concepts are difficult to deliver meaningful thermal output, and suggest alternative design strategies for future magnetocaloric systems to apply the intrinsic asymmetry of the magnetization curve and achieve constructive net cooling.