On the relevance of temperature, applied magnetic field and demagnetizing factor on the performance of thermomagnetic motors

Thermomagnetic motors are devices capable of converting heat into work with high efficiency relative to the Carnot efficiency. This work reports how the temperature, applied magnetic field, and demagnetizing factor, change the performance of thermomagnetic motors, using a thermodynamic approach. Results show that these systems present high efficiency related to the Carnot efficiency for small temperature differences and better correlation between work produced by cycle and relative efficiency when the magnetic transition occurs. The relation of work and relative efficiency can also be improved by increasing the applied magnetic field change and reducing the demagnetizing factor. For some special temperature conditions, a lower magnetic field change can result in higher work production. Also the decrease of the demagnetization factor acts as an increase of the magnetic field change applied to the motor magnetic material.