Physics of Thin Film Formation in Microchannels: New Physical Insights and Governing Correlations

摘要

Thin film evaporation is a prominent mechanism of heat transfer in the microchannel flow boiling process, and numerous studies have attempted to predict its contribution to the overall surface heat transfer. In this study, a novel experimental platform capable of producing microscale data with unprecedented spatial and temporal resolutions is utilized to determine the liquid film thickness formed around an elongated bubble. A model is developed to accurately predict surface heat transfer during the thin film evaporation process. First, it is shown that thin film formation and evaporation can be represented in two stages: 1) adiabatic formation of the liquid layer followed by 2) thermal development and evaporation of the liquid film. It is then explained how the liquid layer thickness is affected by the flow parameters.