Temperature Dependence of Heat and Mass Transfer in a Forced Convective Duct Flow with and without Condensation on one Wall

Kurzfassung

Experiments were conducted to investigate condensation in a convective moist airflow in a vertical duct with one cooled wall. Based on temperature and moisture measurements the heat and mass transfer were determined by means of the thermal balance for fixed temperature differences between inflow, wall and dew point temperatures for Re = 2000, 4000, 8000 in a range of wall temperatures T_wall = 1-10 °Celsius. By comparing results obtained in moist airflow with condensation and dry airflow under similar conditions, the impact of the latent heat transfer on the global heat transfer is investigated. While the mass transfer revealed no significant temperature dependence, the condensation heat transfer showed an increase for elevated temperatures. The release of latent heat signficantly changed the heat transfer mechanism due to the release of heat of evaporation and the layer of condensate on the cooled wall.