Study on high-speed condensation heat transfer of steam/nitrogen mixture in horizontal rectangular channel

In this paper, the steam condensation mixed with nitrogen is experimentally investigated to examine the effect of non-condensable gas on the steam condensation process at high speed. The mass flux of steam/nitrogen mixture is in the range of 159.2-464.6 kg/(m2·s), the nitrogen mass fraction is up to 10%, and the inlet pressure ranges between 0.15 and 0.47 MPa. The mass flow rate of cooling water varies from 300 to 900 kg/h. The effects of mass flow rate of cooling water, nitrogen mass fraction, mass flux of steam/nitrogen mixture and channel configuration are studied. It is found that the increase of mass flux of mixture increases the condensation heat flux, the condensation heat transfer coefficient and the overall heat transfer coefficient. Including the nitrogen into steam deteriorates the condensation process, but the influence of nitrogen on the condensation process at high speed is much smaller compared to that at low speed. The increase of mass flow rate of cooling water promotes the condensation heat flux and the overall heat transfer coefficient, but decreases the local condensation heat transfer coefficient. The channel configuration and the gravity has little effect on the high-speed condensation. Finally, a new fitting correlation is proposed to predict the high-speed steam condensation in the presence of nitrogen based on Shah's correlation.