Theoretical Model for Predicting the Transient Response of the Mixture-Vapor Transition Point in Horizontal Evaporating Flow

Abstract

A horizontal tube evaporator in which complete vaporization takes place can be divided into two distinct regions—a two-phase region and a superheat region. The mixture-vapor transition point refers to the boundary between these two regions. Experimental evidence is presented which indicates that, during steady as well as transient flow conditions, the motion of the mixture-vapor transition point is of an oscillatory nature. Furthermore, the amplitudes of the oscillations appear to be sufficiently random to preclude the possibility of predicting an instantaneous position. Therefore, a theoretical model is proposed for predicting the transient response of the mean position of the transition point. Experimental validation of the theoretical model is reasonably well established.