Numerical investigation on boiling mechanism in porous metals by LBM at pore scale level

Abstract

In the present study, the boiling mechanism in porous metals is investigated by Gong-Cheng phase-change lattice Boltzmann method. The complex geometry of porous metals is implemented in this study, which is different from the previous upscaling studies of boiling in porous metals, such as the method of representative elementary volume (REV). The detailed ebullition process at pore scale level is revealed, and the effects of wettability, porosity and porous structures on bubble behaviors and heat transfer are further analyzed. We found that bubble coalescence helps bubbles to be squeezed out of pores and bubbles accumulate more closely at the solid surface with increasing static contact angle. A thin liquid film forms between the bubble and solid surface with the static contact angle of 46.2°. Bubbles at the bottom of the porous metals are hard to escape, and bubbles coalesce frequently at the bottom of porous metals with lower porosity. Bubbles escape more easily in gradient porous metals than uniform porous metals in flow boiling simulation.