Heat Transfer Characteristics of Passive Condensers for Reactor Containment Cooling

Passive condensers that are based on gravitational force do not require pumps or blowers to move fluid and, hence, are considered as safety measures in nuclear power plant containment cooling. In this paper vertical tube passive condensers with the tube inside condensation and cooled by a secondary pool of water are discussed as applied to reactor containment heat removal system. Series of experiments were carried out on scaled separate effects test facilities with vertical single tube and four tube bundle condensers. The results of experimental data on the rate of condensation heat transfer, the effects of noncondensable, and parametric effects, such as pressure, tube diameters and lengths, obtained from single tube and tube bundle passive condenser are presented. The data on the tube bundle indicated larger condensation heat transfer due to enhanced heat transfer in the secondary cooling. For tube bundle condensation, the turbulent mixing on the secondary pool side decreases the temperature difference between pool water and condenser tube outer wall, causing an increase in secondary heat transfer. Theoretical models on tube condensation based on heat and mass analogy and boundary layer models were developed. The data were compared with theoretical models and good agreement was observed between theoretical predictions and single tube condensation heat transfer data. For the tube bundle condenser, the theoretical model agreed with data when the secondary side enhancement in heat transfer due to turbulent mixing in the flow boiling was included. Practical heat transfer correlations are presented using available data on passive condensers for reactor application.