Experimental Study on Direct Contact Condensation of Steam Bubbles with Non-Condensable Gas at High Reynolds Numbers

Abstract

Direct contact condensation of steam bubbles with non-condensable gas is common in nuclear safety equipment. To study the effect of non-condensable gas on heat transfer of steam-air bubbles at high Reynolds numbers, a high-speed camera was used to capture the bubbles. The size and upward motion behavior of bubbles were analyzed. The experimental results were compared with correlations proposed by previous works. To better predict the heat transfer coefficient of bubbles at high Reynolds numbers, a modified heat transfer correlation based on the correlation of rigid sphere was proposed which are functions of bubble Reynolds number, liquid Prandtl number, Jacob number, and Strouhal number. This correlation considers both the forced convection and the variations of gas side diffusion resistance. Comparison of experimental data and the predicted values shows that the deviation between the experimental data and predicted values is within ±25%.

Keywords: Direct contact condensation, Non-condensable gas, Heat transfer correlation