Boiling crisis as inhibition of bubble detachment by the vapor recoil force

TL;DR

This paper presents a physical model of the boiling crisis based on vapor recoil, showing how bubble spreading and adhesion lead to vapor film formation, with experimental validation near the critical point.

Contribution

The study introduces a novel vapor recoil-based model for boiling crisis, supported by numerical simulations and experiments under microgravity conditions.

Findings

Vapor recoil causes bubble spreading and adhesion, preventing bubble departure.

Near the critical point, slow bubble growth allows observation of spreading dynamics.

Experimental results confirm increased contact angle and dry spot spreading, supporting the model.

Abstract

Boiling crisis is a transition between nucleate and film boiling. In this communication we present a physical model of the boiling crisis based on the vapor recoil effect. Our numerical simulations of the thermally controlled bubble growth at high heat fluxes show how the bubble begins to spread over the heater thus forming a germ for the vapor film. The vapor recoil force not only causes the vapor spreading, it also creates a strong adhesion to the heater that prevents the bubble departure, thus favoring the further bubble spreading. Near the liquid-gas critical point, the bubble growth is very slow and allows the kinetics of the bubble spreading to be observed. Since the surface tension is very small in this regime, only microgravity conditions can preserve a convex bubble shape. Under such conditions, we observed an increase of the apparent contact angle and spreading of the dry spot under the bubble, thus confirming our model of the boiling crisis.