Mechanistic Modeling of Critical Flow of Initially Subcooled Liquid Containing Dissolved Noncondensables Through Cracks and Slits Based on the Homogeneous Equilibrium Mixture Method

Abstract

A model for critical flow in capillaries and cracks of an initially subcooled liquid containing a dissolved noncondensable gas is presented. The model is based on the iterative numerical solution of, and the imposition of critical flow conditions on, one-dimensional two-phase flow conservation equations, everywhere assuming homogeneous equilibrium two-phase flow, and equilibrium between liquid and vapor-noncondensable mixture phases with respect to the concentration of the noncondensable.

Model predictions are compared with data from two different sources with good agreement, indicating that the assumption of complete equilibrium between the two phases is adequate for estimating the critical flow in microchannels and cracks. The effect of dissolved noncondensables is examined, and it is shown that the desorption of dissolved noncondensables from water can lead to a slight (up to several percent) reduction in the critical flow rate.