Flow boiling of low-pressure water in microchannels of large aspect ratio

Flow boiling heat transfer in microchannels can provide a high cooling rate, while maintaining a uniform wall temperature, which has been extensively studied as an attractive solution for the thermal management of high-power electronics. The depth-to-width ratio of the microchannel is an important parameter, which not only determines the heat transfer area but also has dominant effect on the heat transfer mechanisms. In the present study, numerical simulations based on the volume of fraction models are performed on the flow boiling in very deep microchannels. The effects of the depth-to-width ratio on the heat transfer coefficient and pressure drop are discussed. The bubble behavior and heat transfer characteristics are analyzed to explain the mechanism of heat transfer enhancement. The results show the very deep microchannels can effectively enhance the heat transfer, lower the temperature rise and show promising applications in the thermal management of high-power electronics.