Effects of non-condensable gases on condensation heat transfer

4th RCM on the IAEA CRP on Natural Circulation Phenomena, Modelling and Reliability of Passive Safety Systems that Utilize Natural Circulation
Vienna, Austria, September 10-13, 2007
TECDOC (Draft 2, March 2010) Natural Circulation Phenomena and Modelling for Advanced Water Cooled Reactors, http://www.iaea.org/NuclearPower/NaturalCirculation/nc_tecdoc-draft2.htmlCondensation plays a key role in removing heat in many industrial applications. Presence of even a small amount of noncondensable gas in the condensing vapor leads to a significant reduction in heat transfer during condensation. In nuclear plants, the condensation of steam in the presence of non-condensable gas becomes an important phenomenon during LOCA (Loss of Coolant Accident) when steam released from the coolant system mixes with the containment air. Besides this, ingress of small amount of air affects the performance of the power plant condensers. The effect of non-condensable gases on the condensation of steam has been studied for various geometries (e.g. tubes, plates, annulus, etc.) for these applications. The phenomena have been investigated experimentally and theoretically. A number of correlations have been developed and incorporated in the computer codes available for thermal hydraulic analysis of the various systems.