MECHANISTIC MODELING OF CRITICAL FLOW OF INITIALLY SUBCOOLED LIQUID CONTAINING DISSOLVED NONCONDENSABLES THROUGH CRACKS AND SLITS BASED ON THE HOMOGENEOUS EQUILIBRIUM MIXTURE METHOD

A model for critical flow in capillaries and cracks of an initially su bcooled liquid containing a dissolved noncondensable gas is presented. The model is based on the iterative numerical solution of and the imp osition of critical flow conditions on, one-dimensional two-phase flow conservation equations, everywhere assuming homogeneous equilibrium t wo-phase flow, and equilibrium between liquid and vapor-noncondensable mixture phases with respect to the concentration of the noncondensabl e. Model predictions are compared with data from two different sources with good agreement, indicating that the assumption of complete equil ibrium between the two phases is adequate for estimating the critical flow in microchannels and cracks. The effect of dissolved noncondensab les is examined, and it is shown that the desorption of dissolved nonc ondensables from water can lead to a slight (up to several percent) re duction in the critical flow rate.