A modified force balance model for predicting bubble departure diameter and lift-off diameter in subcooled flow boiling

Abstract

The calculation of heat flux for each component in the wall heat flux distribution model involves a crucial parameter, namely the characteristic bubble diameter. The bubble departure diameter and lift-off diameter are two of the most significant characteristic bubble diameters. In this paper, the bubble growth rate and bubble force analysis in subcooled flow boiling under various inclination angles of the heating surface are investigated, and the bubble departure and lift-off diameters are calculated based on force balance. According to the energy balance method, a superimposed bubble growth model is proposed that incorporates the effects of superheated layer evaporation around the bubble, microlayer evaporation, and condensation at the top of the bubble on the bubble growth rate. This paper proposes a force balance model for heating surfaces with varying inclination angles, based on accurate calculations of wall superheat. The model has been validated by a large amount of experimental data and exhibits superior accuracy and stability compared to existing models.