Assessment of the performance of dielectric fluids in microchannel heat sinks

The merits of water-fed microchannel heat sinks have shown that the technology may be a plausible and effective cooling solution for the ever-increasing power dissipation of high-speed microprocessors. Favorable factors such as high heat transfer surface area and heat flux removal for reasonable operating pressures, as well small heat sink mass and volume continue to drive the technology. However, ionic water's extremely low electrical resistivity and the potential for hazardous interaction with an active microprocessor have justifiably caused apprehension to close-proximity implementation of microchannel heat sinks. Dielectric fluids can be utilized closer to the active processor than water, but generally have much lower thermal transport capability. In this numerical study, an environmentally-friendly dielectric fluid with higher resistivity than water, but lower thermal transport capability is employed in channels fabricated directly into the backside of a microprocessor. The cooling capability of the dielectric close-proximity microchannel heat sink is evaluated, and found to be ineffective. A Brownian-motion based empirical model of the enhancement of thermal conductivity of the dielectric by nanoparticle loading is employed in order to gauge possible increase in effectiveness. It is found that the thermal transport capability of the dielectric is significantly improved by nanoparticle suspension. Temperature-dependence of thermophysical properties is implemented in the model.