Phenomenological model for a first-order magnetocaloric material

In order to predict the potential of magnetocaloric heating and cooling devices, system simulations are an essential instrument. These simulations, in turn, depend to a large extent on the model implemented for the magnetocaloric material. Magnetocaloric materials with a first-order phase transition, such as found in some La(Fe,Mn,Si)13-based alloys, show excellent magnetocaloric properties. The aim of this work is thus to provide a material model for a first-order La(Fe,Mn,Si)13-based alloy. The model is tailored to be used in system simulations. This includes thermodynamic consistency of the model and a relatively simple implementation. All relevant equations of the material model are determined from the specific heat capacitance as function of the temperature and the magnetic field. Since all equations are derived from the same base equation, they are consistent in terms of the first and second law of thermodynamics. As base function for the specific heat capacitance, a modified Cauchy-Lorentz function is used. The model parameters are determined from experimental data. Consistency of the model is verified with further data. The present model enables the simulation of the exergetic efficiency of a magnetocaloric cooling or heating device based on first-order La(Fe,Mn,Si)13 alloys.