Quantitative observation of co-current stratified two-phase flow in a horizontal rectangular channel

The main objective of this study is to investigate experimentally the two-phase flow characteristics in terms of the direct contact condensation of a steam–water stratified flow in a horizontal rectangular channel.Experiments were performed for both air–water and steam–water flows with a co-current flow configuration. This work presents the local temperature and velocity distributions in a water layer as well as the interfacial characteristics of both condensing and noncondensing fluid flows.The gas superficial velocity varied from 1.2 m/s to 2.0 m/s for air and from 1.2 m/s to 2.8 m/s for steam under a fixed inlet water superficial velocity of 0.025 m/s. Some advanced measurement methods have been applied to measure the local characteristics of the water layer thickness, temperature, and velocity fields in a horizontal stratified flow. The instantaneous velocity and temperature fields inside the water layer were measured using laser-induced fluorescence and particle image velocimetry, respectively. In addition, the water layer thickness was measured through an ultrasonic method.