Analysis Of The Enhanced Heat Exchange Characteristics Of The CPL System Used To Cool The Electron Devices

As a new technique in the field of microchannel phase-change heat transfer, micro-capillary grooved heat sink can drive fluid flow by capillary force and create enhanced evaporation heat transfer conditions by promoting the formation of an extended meniscus in the three-phase contact-line region of a microgroove. It has been used to achieve the heat exchange with high heat transfer coefficient and high heat flux.The main purpose of the present dissertation is to clarify wetting (dry-out), flow and phase-change heat transfer behavior and mechanisms in vertical rectangular capillary microgrooves experimentally and theoretically. Two phase-change heat transfer mechanisms are advanced for the enhanced heat transfer process in the microgrooves. One of them is pure evaporation heat transfer model in the extended thin film region near the triple-phase contact line of vapor-liquid-solid at lower input heat flux. The other one is combined heat transfer model of evaporating heat transfer in the extended thin film region near the triple-phase contact line of vapor-liquid-solid and boiling heat transfer in the intrinsic meniscus region at higher input heat flux. Through the theoretical studies of liquid wetting characteristics in vertical rectangular capillary microgrooves, the proposed theoretical model for liquid wetting characteristics in the microgrooves could predict the meniscus dry-out point well. And it could explain the mutual influence between wetting behavior and phase-change heat transfer. Following the research on the heat sink unit of vertical rectangular capillary microgrooves, an enhanced evaporation heat transfer model is developed in the thin film region and the enhanced evaporation heat transfer mechanisms are advanced in the thin film region at lower input heat flux. Finally, flow boiling heat transfer correlations presented in recent years are collected and analyzed.