Parametric Analysis on Magnetoresistive Heat Switch – Numerical Study

Abstract

The magnetoresistive property of the heat switch plays a vital role in deciding the thermal performance of an Adiabatic demagnetization refrigerator. The thermal conductivity of magneto-resistive heat switchesis affected by several factors, such as the material's properties, the magnetic field that is being applied, the temperature, the design, and the structure. Magneto-resistive behaviour is particularly for materials such as tungsten, gallium, cadmium, gallium, etc., which are switching elements. In the present study, the magneto-resistive behaviour of tungsten is analysed with the help of COMSOL. Transient analysis is selected in the study. The magnetic field increases linearly with time and follows the expression of 0.09×t. The maximum magnetic field induced is approximately 2.75 T at 30 seconds. It is observed that magnetoresistance rises with an increase in a magnetic field. However, in the OFF state, due to magnetoresistive behaviour thermal gradient is formed over MRHS. Due to the temperature difference, thermal conductivity is not constant throughout the tungsten. The maximum temperature difference between the upper and lower flange of MRHS in the OFF state is 0.11 K. However, in the ON state temperature difference between the upper and lower flange is approximately 0.1 K. It is evident from the analysis that thermal conductivity will not be constant throughout MRHS in the OFF state. Hence, the simulation should also follow experimental testing to determine the exact thermal conductivity results.