Numerical simulation of bubble dynamics in pool boiling at heated surface

•The dynamics of bubble growth and departure in pool boiling at surface in low pressures considering both macrolayer and microlayer evaporation.•We propose a new asymptotic solution for bubble growth in low pressures.•The effect of superheat on the shape of growing bubbles. In this work, we investigate numerically the dynamics of bubble growth and departure in pool boiling at surface in low pressures using the asymptotic solution derived from our semi analytical method and considering both macrolayer and microlayer evaporation. Our asymptotic solution for bubble-growth kinetics is capable of computing bubble departure diameter Dd and growth time tg more accurately in higher superheats at atmospheric pressure, in which the existing asymptotic growth-kinetics are not adequate. It does not apply in low pressures, particularly below atmospheric pressure. We therefore propose a new asymptotic solution of growth kinetics for computing bubble departure in low pressures. A steady-state analysis of force balance equation in low pressure yields a power-law variation of Dd with Jakob number and pressure. The bubble departure with and without microlayer evaporation reveal that the method with dynamic microlayer evaporation predicts Dd and tg more accurately. The effect of superheat on the shape of growing bubbles reveals that spherical bubbles form at low superheat and hemi-spherical bubbles at high superheat.