Direct contact condensation of superheated steam on subcooled water in a vertical rectangular channel

Abstract

The present study is direct contact condensation experiment for co-current flow in a vertical rectangular channel. The experiment is performed with superheated steam and subcooled water as working fluids. A vertical rectangular channel has a length of 40 cm, a width of 65 mm and a height of 35 mm. Water flow rate, steam flow rate, the degree of subcooling and the degree of superheating are considered as main test parameters. Especially, the degree of superheating is the most important parameter in this study. In the present experiments, total 140 data of heat transfer coefficients are obtained from the various experimental conditions. The water film is very thin, and has complex interface. The flow regime transition does not occur in the present experimental conditions. The heat transfer coefficient (HTC) increases with increase of steam and water flow rates, and is little more sensitive to the steam flow rate than water flow rate. The average heat flux is not affected by steam superheating. However, the HTC is decreased with steam temperature increasing. From the present data, empirical correlation and correcting method are developed in terms of easily accessible parameters for practical purpose. Especially, the correcting method makes it possible to represent the existing correlations. A great difference exists between the present data and several existing correlation.