Boiling crisis controlled by capillary pumping and viscous friction: Liquid penetration length and dry spot diameter Available to Purchase

A boiling crisis, or critical heat flux (CHF), is a condition that determines the upper bound on removable thermal energy at a boiling surface. In such situations, the liquid cannot wet the surface because a vapor film completely covers it. CHF is enhanced on micro-structured surfaces when under boiling conditions. CHF values were measured for surfaces with rectangular microchannel geometries of various channel widths, (10–30 μm) and generally increased in value as channel widths decreased. However, the CHF value for the 5-μm channel-width surface was found to be lower than the wider channel-width surfaces. This observation contradicts models based on vapor recoil and classical instability mechanisms. Hence, we present a fluid-dynamics model that considers capillary pumping and viscous friction. With a focus on the spatial distribution of the liquid penetration region and the local dry spot under a large vapor bubble, this model can accurately predict the CHF variation associated with different channel widths.