Modified mean-field theory with phenomenological model of volume effects for 1st order transition magnetocaloric materials
Résumé
The simulation of an Active Magnetic Regenerator (AMR) behavior in a numerical model is strongly dependent on the Magnetocaloric Material (MCM) data. The Bean and Rodbell theory [1] is often used in order to model 1st order transition MCM. However, its results can differ from experimental measurements with a non-zero magnetic field. In this paper we present a phenomenological model introducing the effect of the volume change of the MCM on its magnetic and calorimetric behavior. We use a shape function to adapt the exchange interaction. The free parameters of the model are adjusted with respect to experimental measurements of magnetization and heat capacity. Volume change is deduced to minimize the Gibbs free energy. These more representative modeled data of strong 1st order MCM can be used for the simulation of the magneto-thermodynamic cycles at work in the MCM with an improved accuracy.