Numerical Investigation of Electronic Liquid Cooling Based on the Thermomagnetic Effect

Liquid cooling for thermal management has been widely applied in high power electronic systems. Use of pumps may often introduce reliability and mechanical limitations such as vibration of moving parts, noise problems, leakage problems, and considerable power consumption. This paper presents a theoretical design of circulating a liquid coolant using magnetic and thermal fields which surround high power electronic systems by means of thermomagnetic effects of temperature sensitive magnetic fluids. Numerical simulation models of the heat transfer process from a magnetic liquid contained in a closed flow loop in the presence of an external magnetic field have been developed. These models include the coupling of three fundamental phenomena, i.e. magnetic, thermal, and fluid dynamic features. In this cooling device, the thermomagnetic convection is generated by a non-uniform magnetic field from a solenoid, which is placed close to the fluid loop. The device cooling load is calculated in the region near the solenoid. No energy is needed, other than the heat load (i.e. waste heat from actual electrical device), to drive the cooling system, and as such, the device can be considered completely self-powered. In effect, the heat added to the ferrofluid in the presence of a magnetic field is converted into useful flow work. In this numerical study, the effects of different factors such as input heat load, magnetic field strength and magnetic distribution (based on solenoid dimensions and the applied electrical current) along the loop, on the performance of the cooling system are analyzed and discussed. Finally, the variation of the local Nusselt number along the heated and cooled regions of the flow loop are calculated and compared with laminar entry length analytical solutions.