Heat Transfer Modeling of Confined Bubble Evaporation in a Microchannel

Abstract

In this study, we model the heat transfer mechanism for a single nucleate vapor bubble which then expands to an elongated bubble during evaporation in a microchannel. The model is a logical mix of empirical correlations and analytical models and is defined for the two steps of bubble growth including: (a) partially confined growth, in which the bubble expands from nucleation site until it fills the entire cross-section of the channel, and (b) fully confined growth, in which the bubble reaches the side walls and begins to elongate axially in downstream direction. To estimate the heat transfer characteristics of vapor bubble growth during evaporation in the microchannel, the time variation of liquid film thickness and bubble nose position are evaluated. Finally, a time-averaged value of local heat transfer coefficient is obtained for a period of time using available heat transfer correlations for each heat transfer process separately.