Modeling of Thin-Film Multi-Phase Heat Transfer With Statistical Thermodynamics

The power densities on computer chips have continued to rise, and power maps are further complicated by the addition of multiple cores. This in turn has made it very hard to achieve uniform junction temperatures across a device. Liquid cooling solutions, such as spray cooling, have the capability to remove the heat from the chips and maintain uniform junction temperatures. For the best possible performance, the contribution of bubbles in the flow must be better understood. Near a heat transfer surface, a temperature gradient exists in the flow. At the surface of the bubble, the fluid will vaporize or condense, depending on the local vapor and liquid temperatures and energy states at a given location. This means that a bubble can act as a heat pipe in certain conditions and move a large amount of heat with no net vapor generation. A model was written using the Statistical Rate Theory and principles of irreversible thermodynamics to analyze the amount of heat that is removed by a bubble at or near the surface through both latent and heat pumping effects.