Heat and Mass Transfer in forced convective Duct Flow with Condensation on one Wall

Abstract

The process of condensation in convective air flows occurs frequently in many technical applications. Often condensation leads to negative effects. For instance, condensation in the gap between fuselage and cabin wall of an aircraft may penetrate the insulation packages thus in a smaller insulation effect, higher weight and corrosion [1]. Moreover, condensation represents a potential danger for road traffic due to mist on wind screens of cars [2]. However, due to the complex mutual interplay of phase transition and forced convection in moist air flows, a prediction of the resulting mass and heat transfer often fails or is impossible. An experimental study is carried out with the objective to find out how the mass and heat transfer scale in such flows. The measurements are performed in a duct with a rectangular cross section and an isothermally cooled wall on one side and adiabatic conditons on the other side walls. With dimensions of W x H x L = 0.53 m x 0.05 m x 2.05 m the aspect ratio is 10.66:1.In the current study, dew point and temperature measurements are performed in order to verify the global heat and mass transfer as a function of moist air flow rates and temperature levels at Re ≈ 4000 and Re ≈ 8000. The chosen parameter range represents the transition between laminar and turbulent flow. At the conference we like to present the results and analysis of the Nusselt and Sherwood number dependency to identify the impact of the mass transfer due to condensation on the heat transport. Therefore, the results are compared to dry air measurments for reference.