Experimental study of the effect of non-condensable gases on steam condensation over a vertical tube external surface

An experimental investigation has been conducted to evaluate the steam heat removal capacity with non-condensable gases (e.g. air, helium) over a vertical tube external surface. Under steam/air condition, condensation heat transfer coefficients have been obtained under the wall subcooling ranging from 27 to 70 °C, total pressure ranging from 2.0 × 105 Pa to 6.0 × 105 Pa and air mass fraction ranging from 0.10 to 0.80. The experiments for the influence of the wall subcooling on the steam condensation heat transfer with a fixed pressure and air mass fraction have been performed. An empirical correlation for the heat transfer coefficient is developed, covered all data points within 10%. Under steam/air/helium (simulating hydrogen) condition, the effect of helium mole fraction in non-condensable gases on the heat transfer coefficient was investigated under the wall subcooling ranging from 30 to 62 °C, total pressure ranging from 2.0 × 105 Pa to 5.0 × 105 Pa, air mass fraction ranging from 0.09 to 0.76 and helium mole fraction in non-condensable gases from 0.03 to 0.35. The empirical correlation that got from the helium experiments covered data with 20%. There was not found the helium stratification under the experimental conditions.