The technology used by MagnoTherm Solutions is based on the magneto-caloric effect (MCE), which manifests itself in a temperature change of a magnetocaloric material (MCM) when a magnetic field is applied. The operation of a magnetic refrigeration cycle is based on the cyclic application of the MCE.
The figure shows the scheme of such a cooling cycle. In the initial state, the magnetic moments are randomly oriented (ΔT=0). When the material is adiabatically magnetized, the magnetic moments align with the external magnetic field lines. Because of the MCE, the temperature of the material increases (ΔT>0) by an increase of the material’s thermal entropy compensating for the material’s decreased magnetic entropy. By expelling the excess heat in the applied magnetic field, the material is cooled to its initial temperature (ΔT=0). The subsequent adiabatic demagnetization of the material is accompanied by a decrease of the temperature, again because of the MCE (ΔT<0). Thereby, the material is able to absorb heat from the cooling cabinet.
With cyclic application, a cooling process can be realized similar to the gas compression cycle.