Forced condensation heat transfer characteristics of vapour in the presence of noncondensable gas in horizontal tubes operating at high pressures

The forced condensation heat characteristics of vapour in the presence of noncondensable gas at high pressures are investigated. A three-dimensional computational model is proposed and the Lee condensation model is employed to simulate mass and energy transfer processes via interfaces. Numerical simulations are then performed to investigate flow and heat transfer characteristics of vapour in the presence of noncondensable gas at the operating pressure of 10 MPa. It is found that the buoyancy force influences the flow structure via the induced secondary circulation in a horizontal tube. The film thickness is increasing at the bottom wall, while the water film at the top wall first increases and then decreases downstream the tube due to gravity effects. Therefore, the heat transfer coefficient at the top wall is decreased along the tube due to reduced temperature difference. The decreasing heat transfer coefficient is also found at the bottom wall, however a roughly constant value is then attained downstream the tube. In addition, increasing the operating pressure attenuates the heat transfer performance of gas mixture. The work provides a new insight into flow and heat transfer characteristics of vapour in the presence of noncondensable gas in horizontal tubes at high pressures.