Boiling heat transfer characteristics and numerical simulation in microchannel two-phase flow with complex overload vector

Proton exchange membrane fuel cells (PEMFCs) find extensive use in hydrogen powered aircraft systems owing to their advantageous low operational temperatures and high power density characteristics. Thermal accumulation during operation induces temperature elevation, which detrimentally influences PEMFC performance metrics. Phase-change cooling methodologies effectively mitigate the inherent limitations associated with conventional thermal management approaches. This research numerically investigates boiling heat transfer phenomena and flow behavior within microchannels under varying overload conditions. Analysis of gravitational vector effects on microchannel thermal performance during boiling processes reveals two critical relationships. Heat transfer degradation is significantly correlated with the included angle ( β ) between the overload vector and the main flow direction. In addition, reducing the magnitude of overload acceleration ( a ) leads to a premature precipitous decline in the total heat transfer coefficient ( h ) curve. The peak value of the pipeline's curve of h will sharply decline as the overload acceleration rises. The connection between h and the overload vector is fitted using the boiling heat transfer properties of the microchannel under various overload vectors; the inaccuracy ranges from 0.1% to 7%. • Microchannel flow pattern transitions under complex gravitational acceleration • Impact of vapor quality on heat transfer in microchannels during phase transition • Impact of gravitational acceleration on thermal transfer in microchannels • Impact of gravitational acceleration direction on microchannel thermal transfer • Formula establishment for heat transfer coefficient and gravitational acceleration correlation