(A) study on the characteristics of direct contact condensation of a steam jet into a quenching tank through a single horizontal nozzle

Abstract

Phenomena of direct contact condensation (DCC) heat transfer between steam and water are characterized by the transport of heat and mass through a moving steam/water interface. Application of the phenomena of DCC heat transfer to nuclear power plant operations and chemical processes provides some advantageous features in the viewpoint of enhanced heat transfer. The purpose of this study is to improve the understanding of the characteristics of DCC of stable steam jets discharging from a single horizontal pipe into a quenching tank filled with subcooled water. This study includes both the experimental studies, which deal with the condensation characteristics of stable steam jets, and theoretical studies, which present a modeling for the best representation of the experimental results. Experiments have been performed for five horizontal nozzles with different inside diameters by changing the experimental parameters such as steam mass flux, pool temperature and nozzle inside diameter. Effects of the parameters on the experimental results have been analyzed. Analysis of the condensing steam jets by reviewing pictures taken by a high speed video camera showed that two types of steam jet such as ellipsoidal shape and conical shape were typically observed for a stable steam jet, depending on the steam mass flux and pool temperature. The steam jet expansion ratio, defined as a ratio of the maximum steam jet diameter to the nozzle inside diameter, and the dimensionless steam jet length, defined as a ratio of the steam jet length to the nozzle inside diameter, were measured. The average condensation heat transfer was calculated by defining the surface area of steam jet cavity. The effect of steam mass flux, pool temperature and nozzle inside diameter on these condensation parameters were discussed. Empirical correlations for the dimensionless steam jet lengths and the average condensation heat transfer coefficients as a function of dimensionless steam mass flux and conde...