A self-regulating multi-torus magneto-fluidic device for kilowatt level cooling

Abstract

Efficiently removing waste heat by novel cooling devices can reduce material failure and enhance service life. Magneto-fluidic cooling, which is based on the thermomagnetic convection of a ferrofluid, offers a passive, self-regulating approach for the removal of waste heat. The performance of a novel multi-torus magnetic cooling device for kilowatt level cooling was investigated. The performance was determined for a range of heat load power. Heat load cooling increased from 148 °C to 214 °C when heat load power was increased from 0.5 kW to 1 kW, respectively, demonstrating the self-regulating nature of the device. The heat load cooling performance was assessed for various magnet positions. The temperature profile of the ferrofluid along the axial and radial directions of the flow channel revealed an asymmetric temperature distribution. The transient effect of periodic magnetic field switching on the heat load temperature was simulated using COMSOL Multiphysics and found to be in good agreement with the experimental findings. Simulated surface velocity vector plots revealed ferrofluid vortices near the heat load, these vortices resulted in enhanced mixing of hot and cold ferrofluid, leading to increased cooling. The thermal resistance of our multi-torus magnetic cooling device was determined analytically. The present device offers lower thermal resistance per unit length and lower ferrofluid thermal resistance per unit volume of ferrofluid compared to conventional heat pipes. A self pumping, self regulating passive heat pump, capable of kilowatt level cooling, has been fabricated and its cooling performance assessed.