Numerical Simulation of Convective Condensation of Steam with Large Proportion of Non-condensable Gas under High Pressure

This study simulates the convection condensation heat transfer phenomenon of steam containing non-condensable gas(NCG) in the thermal power system of an underwater vehicle at a large sea depth. First, the condensation process is modeled by defining the source terms of the continuity, momentum, component transport, and energy equations. To verify the validity of the numerical model, classical Kuhn experimental conditions are then simulated, with results matching well with the experimental data. The maximum error of the heat-transfer coefficient is found to be less than 20%. Accordingly, the study then simulates the condensation heat-transfer process of different proportions of steam and NCG under 10 MPa pressure. During the simulation, the effect of the condensed liquid film is considered, and the influence of the NCG on the condensation heat transfer of steam under high pressure is analyzed in terms of heat flow density, liquid film thickness, saturation temperature, and condensation mass flow. Results show that the average heat flux of the steam condensation heat transfer is reduced by 50% until the NCG mass fraction reaches 30%. Finally, the simulation conditions are compared with the research on steam containing NCG under atmospheric pressure, with results showing that the inhibition effect of NCG on steam condensation heat transfer is reduced under high pressure.