An Experimental Investigation Into the Oscillatory Motion of the Mixture-Vapor Transition Point in Horizontal Evaporating Flow

A horizontal tube evaporator in which complete vaporization takes place can be divided into two distinct regions: a two-phase region and a super heat region. The mixture-vapor transition point refers to the boundary between these two regions. Experimental evidence indicates that, during steady as well as transient flow conditions, the motion of the mixture-vapor transition point is of an oscillatory nature. This study is concerned with the statistical characteristics of these oscillations, the physical mechanisms causing them, and the influence of various evaporator parameters. Experimental data are presented which indicate that the statistical characteristics of the transition point oscillations can be described by a transformed Rayleigh distribution, and that the inlet flow quality and evaporator heat flux have a considerable influence on this distribution.