Numerical Investigations on Structure Effect for Steam Condensation in the Presence of Air Under Vertical Condition

Abstract

Steam condensation in the presence of non-condensable gas is a general phenomenon in various industrial applications. It has been broadly investigated by experimental studies and numerical analyses. Previous experimental studies and numerical analyses have focused on single structure. To evaluate the condensation heat transfer characteristics of steam for various condensation structure, the present work conducted numerical simulations based on various structure at a wide parameter range (pressure from 0.2 to 1.6 MPa and air mass fraction from 0.16 to 0.71). In the assessments, the condensation heat transfer coefficient with various condensation structure (single tube, plate, cylinder, spherical) were investigated. The results indicate that the structure of the condensation surface has a significant effect on the heat transfer characteristics of steam condensation. There is almost no difference in the heat transfer performance of the four condensation structures under the low pressure and high air mass fraction condition. With the increase of pressure and the decrease of air mass fraction, the heat transfer performance of the cylinder is the best, followed by the spherical and plate, and the worst is the single tube. In addition, the condensation heat transfer coefficient (CHTC) of the cylinder can be 40% greater than that of the single tube at a pressure of 1.6MPa and an air mass fraction of 0.16.