Experimental Study On Steam Condensation Heat Transfer With Noncondensable Gas Over A Vertical Smooth Surface

After the Fukushima accident,people are more concerned about the integrity of the containment in the case of accident.Passive containment cooling system is widely used in the design of the new generation reactor.The passive containment cooling system can not only rely on external power sources under accident conditions,but only rely on physical laws to export heat into the external environment.The existence of non condensable gas restricts the process of condensation heat conduction in the containment.Based on the above background,this paper has carried out an experimental study on the condensation of air-vapor containing the vertical polishing tube and the chrome plated tube.In this paper,we compare the measured values of Nu and D-B formulas in Nu,and analyze the measurement errors of different temperature measurement modes to determine the best way of temperature measurement and check them.The condensation heat transfer characteristics of polishing tube under pure steam condition and air condition were studied by experimental method,and the results were compared with the experimental results of smooth tube.In the pure steam condition,polishing tube relative to the Smooth tube has a weak enhancement effect,in the experimental range,the strengthening effect is about 1.04~1.2 times of smooth tube.Under air condition,the enhancement effect of polishing tube is limited relative to that of Smooth tube.Meanwhile,with the increase of air content,the effect of polishing tube is becoming weaker and weaker,and eventually it will not have enhancement effect.The condensation heat transfer characteristics of Chrome plated tube under pure steam and air conditions were studied by experimental method,and the results were compared with those of bare tube experiments.In the pure steam condition,the chromium plating tube has a stronger heat transfer effect than the polishing tube.The condensation heat transfer coefficient of the chromium plated tube can reach 1.2 to 1.5 times the condensing coefficient of the polished tube.The condensation mode of the surface steam of the chromium plated tube is not completely bead shaped.Under the condition of air,the heat transfer ability of chromium plated tube is better than that of the polished tube at low air content,but its strengthening effect is not obvious.With the increase of air content,the strengthening effect of chromium plating tube is smaller.When the air content exceeds 50%,The heat transfer performance of the chromium plated tube is similar to that of the polishing tube.