Influence of Various Parameters on the Onset Criteria for Boiling Entrainment from a Falling Liquid Film

Abstract

Many studies have been conducted so far on droplet entrainment in annular two-phase flow, but knowledge on boiling entrainment phenomenon is still insufficient particularly when forced-convective gas flow is present. Since the gas flow affects the flow field and nucleate boiling heat transfer in the liquid film, it would also affect the rate of boiling entrainment. Thus, the effects of gas flow on the process of boiling entrainment were explored experimentally in this study. It was found that no boiling entrainment occurs at low heat flux but two types of boiling entrainment called ‘jet-type’ and ‘filament-type’ occur at higher heat flux. In the present experimental conditions, the minimum heat flux needed to cause the two types of boiling entrainment increased with an increase in the gas flow rate.