High Heat Flux Cooling Technologies Using Microchannel Evaporators: Fundamentals and Challenges

Flow boiling in multi micro-channel evaporators is a promising approach to cooling high heat flux in many devices. Understanding of the fundamentals of flow boiling in multi microchannel evaporators is urgently needed. This paper presents a critical review on the research of flow boiling phenomena in microchannels. First, classifications of macro- and micro-channels are briefed. Then, studies on flow boiling in multi microchannels with plain surface are analyzed. Next, studies of flow boiling in multi microchannels with various enhanced technologies are analyzed. Finally, heat transfer mechanisms and development of prediction methods are discussed. According to the critical review and analysis of the current research on the fundamental issues and challenges of flow boiling in micro-channels, future research needs have been identified and recommended. In general, systematic, and accurate experimental data of flow boiling in micro-channels are needed by using advanced measurement technologies. In particular, optimal design of microchannel evaporators with plain surface and enhanced structures is lacking and should be investigated. The physical mechanisms of flow boiling should be further investigated based on the corresponding flow patterns. Furthermore, mechanistic prediction methods should be developed. Furthermore, systematic experimental, analytical and modeling studies on transient flow boiling phenomena in micro-channels should be conducted to understand the physical mechanisms and develop the theoretical models.