Is CHF triggered by the vapor recoil effect?

TL;DR

This study investigates the boiling crisis mechanism near the critical pressure, using experiments and numerical modeling to evaluate if vapor recoil triggers CHF, highlighting the role of dry spot growth and fusion.

Contribution

The paper provides experimental evidence and numerical validation supporting vapor recoil as the trigger for the boiling crisis near CHF conditions.

Findings

Dry spot growth and fusion are observed near CHF.

Experimental results align with vapor recoil model predictions.

Boiling crisis can be triggered by vapor recoil effects.

Abstract

This paper deals with the triggering mechanism of the boiling crisis, a transition from nucleate to film boiling. We observe the boiling crisis in pool saturated boiling experimentally at nearly critical pressure to take advantage of the slowness of the bubble growth and of the smallness of the Critical Heat Flux (CHF) that defines the transition point. Such experiments require the reduced gravity conditions. Close to the CHF, the slow growth of the individual dry spots and their subsequent fusion on the transparent heater are observed through the latter. As discussed in the paper, these observations are consistent with numerical results obtained with the vapor recoil model of the boiling crisis.