Forced convective condensation inside a vertical tube with a steam-noncondensable gas mixture

Passive Containment Cooling System (PCCS) is proposed in advanced nuclear reactor designs for removing heat from the containment in case of an accident scenario. One of the PCCS designs features a system with condensers immersed in the water pool, serving as an ultimate heat sink. Steam mixes with air, enters vertical-tube condensers, and condenses via annular film forced flow of steam hindered by noncondensable gases. In the first part of the article, experimental studies have been covered. The experimental studies performed by researchers cover the range of inlet air mass fraction from 0 to 50 %, steam flow rate from 0.0016 to 0.0183 kg/s and total pressure from 0.03 to 7.5 MPa. In the second part, various correlations developed are discussed, which account for thermal-hydraulic parameters and nondimensional numbers. An assessment of these correlations is performed. In the third part, parametric effects and results obtained from the theoretical model, along with a comparison with experimental data and correlations, are discussed. The analysis performed covers the range of inlet air mass fraction from 11 to 52 %, steam flow rate from 0.004 to 0.03 kg/s and total pressure from 0.21 to 0.49 MPa. It has been found that heat transfer coefficient depends strongly on the mixture Reynolds numbers. It decreases sharply in the initial length of the tube and then slowly as the mass fraction of noncondensable gas increases along the length. The effect of film roughness and developing length is found to be negligible on the heat transfer coefficient.