Heat transfer characteristics of a binary thin liquid film in a microchannel with constant heat flux boundary condition

Thin film evaporation of multi-component fluids in microchannels is important in many industrial applications, which requires comprehensive modeling of the transport mechanisms in the liquid, gas and solid phases. This paper presents a numerical study on the heat transfer characteristics of a binary thin liquid film in a microchannel with constant heat flux boundary condition, using the enhanced Young-Laplace equation that considers the effect of disjoining pressure for binary fluids. Effects of temperature, microchannel size, and non-condensable gas on the binary thin film heat transfer was analyzed. The results show that the thin film contribution to the total heat transfer rate reduces when the initial temperature increases, but the difference between them decreases as the microchannel size reduces. Size effect can be prominent when the characteristic microchannel size is smaller than 10 μm. When the microchannel size decreases, the cumulative heat transfer rate across the interface of the solution decreases, while the thin film contribution to the total heat transfer rate increases obviously. The non-condensable gas deteriorates the cumulative heat transfer rate, but the deterioration reduces under the high temperature condition as compared to that under the low temperature condition. Comparison of the results shows that the temperature and microchannel size have the greatest effect on the heat transfer followed by the non-condensable gas. This can be efficiently utilized for heat transfer enhancement and thermal design in applications involving phase-change heat transfer of multi-component fluids in microchannels.