Study on vapor condensation heat transfer to liquid spray

Related to the cooling and pressure control in the PWR, BWR and PHWR systems, the condensation heat transfer of saturated steam to a hollow cone spray of subcooled water was investigated experimentally and analytically. It has been found that the measured spray water temperature rises more steeply in flow direction than those obtained in the previous studies because smaller thermocouple used here is capable of measuring the temperature in the thin water sheet and water droplets more accurately. The condensation heat transfer coefficient changes in different manner in the axial direction, which suggests the breakup of the sheet into droplets. The condensation heat transfer was estimated using a pure conduction model, and a turbulent thermal conductivity model. A comparison of the predictions with the experimental data indicates that the pure conduction model under predicts the heat transfer in the sheet region significantly, which is better predicted by considering turbulence in the analysis. The heat transfer in the droplet region is closer to the experimental data by considering turbulence in the sheet region and internal circulation and mixing inside the droplets. (author)