Measurement of heat transfer coefficient for direct-contact condensation during bubble growth in liquid

A method to measure the heat transfer coefficient for direct-contact condensation during two-phase bubble formation is proposed. The growth behavior of a condensing vapor bubble at a single nozzle submerged in an immiscible liquid under constant-flow condition was taken by a high-speed video camera. By analyzing the recorded images of bubbles at the nozzle and calculating heat and mass balances at the bubble, the heat transfer coefficients for direct-contact condensation of a two-phase bubble of hexane or vinyl acetate are experimentally obtained. These coefficients depend on the temperature difference between vapor temperature and immiscible liquid temperature, and decrease with increasing temperature difference. The heat transfer coefficients for direct-contact condensation obtained experimentally are compared with those estimated theoretically. Under the present experimental conditions, in the range of the temperature difference less than 14 K, the experimental results correspond well to the theoretical values.