Experimental study of turbulent natural-convective condensation on a vertical wall with smooth and wavy film interface

Abstract

Pressurized water reactor nuclear plants, currently under construction, have been designed with passive containment cooling systems. Turbulent, natural-convective condensation, with high non-condensable mass fraction, on the walls of the containment vessel is a primary heat transfer mechanism in these new plant designs. A number of studies have been completed over the past two decades to justify use of the heat and mass transfer analogy for this scenario. These studies are founded upon natural-convective heat transfer correlations and, in many cases, apply a diffusion layer model to couple heat and mass transfer. Reasonable success in predicting experimental trends has been achieved when correction factors are applied. The corrections are attributed to mass transfer suction, film waviness or mist formation even though little experimental evidence exists to justify these claims. The purpose of this work is to investigate the influence of film waviness and mass transfer suction on the turbulent, natural-convective condensing flow with high non-condensable mass fraction. Testing was conducted using 0.457m×2.13m and a 0.914m×2.13m condensing surfaces suspended in a large pressure vessel. The test facility implements relatively high accuracy calorimetric and condensate mass flow measurements to validate the measured heat and mass transfer rates. Test results show a significant enhancement in heat transfer is caused by disruption of the gas boundary layer due to film waviness. This result has implications for the scalability of existing correlations. A new correlation is proposed and results compared to several datasets.