Influence of wall temperature on condensation rate in duct flow of humid air: a comprehensive computational study

In engineering phase-change phenomena are found in a multitude of applications, ranging from refrigeration and air con-ditioning to steam turbines and petroleum refining. This study investigates the flow of moist air in a circular duct where water vapour condenses in contact with the cold wall of the duct. The investigation delves into the relationship between the condensation mass transfer rate, the heat transfer between the bulk flow and the wall, and the temperature of the wall. The volume of fluid model coupled with the Lee evaporation-condensation model was employed. Five simulations were carried out, involving different wall temperatures while maintaining the same inlet conditions. Condensation was more pronounced at lower wall temperatures, which aligns with the expectations. The heat transfer between the bulk flow and the wall decreased with the decreasing temperature difference. Interestingly, the findings revealed that the surface heat transfer coefficient increased as the wall temperature approached the temperature of the bulk flow. The success of the study suggests potential applications in optimising thermal management systems, with implications for industries where accurate predictions of moisture behaviour and heat transfer are crucial.