2D BEM modeling of a singular thermal diffusion free boundary problem with phase change

TL;DR

This paper presents a 2D Boundary Element Method model for simulating vapor bubble growth during saturated pool boiling, capturing the effects of phase change, surface tension, and vapor recoil forces to understand boiling crisis phenomena.

Contribution

It introduces a novel 2D BEM approach to model singular free boundary problems involving phase change and vapor recoil in boiling.

Findings

Vapor recoil causes rapid dry spot growth under the bubble.

The model predicts transition to vapor film leading to boiling crisis.

Singularity at triple contact point is effectively handled.

Abstract

We report a 2D Boundary Element Method (BEM) modeling of the thermal diffusion-controlled growth of a vapor bubble attached to a heating surface during saturated pool boiling. The transient heat conduction problem is solved in a liquid that surrounds a bubble with a free boundary and in a semi-infinite solid heater. The heat generated homogeneously in the heater causes evaporation, i. e. the bubble growth. A singularity exists at the point of the triple (liquid-vapor-solid) contact. At high system pressure the bubble is assumed to grow slowly, its shape being defined by the surface tension and the vapor recoil force, a force coming from the liquid evaporating into the bubble. It is shown that at some typical time the dry spot under the bubble begins to grow rapidly under the action of the vapor recoil. Such a bubble can eventually spread into a vapor film that can separate the liquid from the heater, thus triggering the boiling crisis (Critical Heat Flux phenomenon).