Transition between thin film boiling and evaporation on nanoporous membranes near the kinetic limit

摘要

In this work, we experimentally studied thin film boiling and evaporation heat transfer of different types of fluids through nanoporous membranes. Transition from thin film boiling to evaporation was observed for the three low surface tension fluids (ethanol, 1PA, and FC-72) but not for water, which was attributed to hotspot formation due to membrane nonuniformity. The transition heat flux for these fluids universally agreed with the model prediction. At the transition points, interfacial resistance dominates the heat transfer behavior which resulted in heat flux and HTC close to the kinetic limit. After transition into the pore-level evaporation regime, the vapor resistance became increasingly dominant and eventually limited the achievable CHF. Our work provides a systematic study of PCHT through nanoporous membranes and can benefit the understanding and application of PCHT through nanoporous membranes for thermal management and modulation.