NONEQUILIBRIUM EFFECTS IN VOID FRACTION DISTRIBUTION

The statistical formulation of two-phase flow is applied to model non- equilibrium effects in a vertical heated channel. The bubble volume di stribution function is integrated to obtain the number density transpo rt equation for boiling flow. Non-equilibrium vapour production is inc luded in the modelling, which was found important to reproduce experim ental data of boiling void fraction distributions. It was found that c alculating j(g) with thermodynamic equilibrium conditions leads to sub stantial overestimations of the void fraction profile.