Enhancement of condensation heat transfer in the presence of non-condensable gas using steam jet method

Abstract

In this study, the use of the steam jet method to destroy the mixed boundary layer of steam and non-condensable gas (NCG) was researched in order to enhance the condensation heat transfer performance. An experimental facility was designed and manufactured in which steam was injected vertically into a single aluminum tube. Both the initial chamber pressure related to the amount of NCG and the bulk chamber pressure after the normal steam injection were tested. The time and enhancement parameters were obtained, including the steam jet continuance time, the maximum heat transfer enhancement ratio, the average heat transfer enhancement ratio and the average overall heat transfer coefficient. The results of the experiment indicate that after the steam jet injection, the maximum heat transfer enhancement ratio increased by at least 137%, and the average heat transfer enhancement ratio increased by at least 118%. In addition, as the NCG mass fraction increased, the values of the continuance time, maximum heat transfer enhancement ratio, average heat transfer enhancement ratio, and average overall heat transfer coefficient improved. Thus, it was confirmed that the steam jet injection method, under the conditions of an accident in which a large amount of NCG flows into the condenser, can effectively improve the condensation performance. Finally, the idea of a bundle-type condenser which is applied by the steam jet method was proposed.