Optimized Expanding Microchannel Geometry for Flow Boiling

This study discusses the simulation of flow boiling in a microchannel and numerically predicts the effects of channel geometry variation along the flow direction. Experimental studies by Pan and collaborators and suggestions from Mukherjee and Kandlikar have generated interest in expanding the cross section of a microchannel to improve boiling heat transfer. The motivation for this geometry change is discussed, constraints and model selection are reviewed, and Revellin and Thome's critical heat flux criterion is used to bound the simulation, via matlab, of separated flow in a heated channel. The multiphase convective heat-transfer coefficient is extracted from these results using Qu and Mudawar's relationship and is compared to reported experimental values. Expanding channel geometry permits higher heat rates before reaching critical heat flux.