DETERMINATION OF THE STEAM-WATER DIRECT CONTACT CONDENSATION HEAT TRANSFER COEFFICIENTS USING INTERFACIAL TRANSPORT MODELS

摘要

Direct contact condensation heat transfer occurring around a stable steam plume in subcooled water has been investigated. The condensation heat transfer coefficients at the steam-water interface have been determined by using three different models, that is, the interfacial transport model due to the turbulent intensity, the surface renewal model, and the shear stress model. The predicted values have been compared with the measured heat transfer coefficients. It is found that the size of eddies developed on the liquid side thermal boundary layer is important in determining the heat transfer coefficient by using the turbulent intensity model. The plume shape factor, which is 1.0 for a conical plume and is less than 1 for an ellipsoidal plumes, is shown to be efficiently used in determining the heat transfer coefficient. For the surface renewal model, the measured plume shape has been used in determining the heat transfer coefficient. The surface renewal model corrected by the plume shape factor was found to be in good agreement with the experimental data. The shear stress model was found to be the same mathematical form with that of the surface renewal model with bigger algebraic coefficient. It is revealed from this study that the size of the eddies and the steam plume shape need to be thoroughly investigated to determine direct contact condensation heat transfer coefficient more practically.