A semi-empirical model for the prediction of heat and mass transfer of humid air in a vented cavity

• Published in: International journal of heat and mass transfer 2023-05, Vol.205, p.123926, Article 123926
• Main Authors: Niehaus, Konstantin, Westhoff, Andreas, Wagner, Claus
• Format: Article
• Language: English
• Subjects: Heat transfer; Humid air; Mixed convection; Mixed convective airflow; Non-condensable gas; Phase transition; Scaling
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2023.123926

•Tomographic Particle Image velocimetry gives insight into the internal flow in a vented cavity.•A 1D-model is suited to describe the heat and mass transfer at Re < 1300.•Direct measurement of condensate and a mass balance approach show quantitative agreement.•A power-law quantifies the mass transfer rate of droplet condensation in humid air. A semi-empirical model to predict the mass transfer rate of water from humid air in mixed convection together with the global heat transfer in a novel experimental set-up is presented. The cuboidal sample consists of isothermally cooled and heated plates with ventilation channels driving a mixed convective flow with inlet channel Reynolds numbers between 210 and 1270, Grashof numbers up to 8.46 ×107, and with relative humidities from 29% to 83% (at 25 ∘C). The volumetric velocity field was measured by means of tomographic particle image velocimetry together with the fluid temperature and humidity. The measurement results are used to develop a one-dimensional model to predict the global heat and mass transfer by quantifying the dependency of the Nusselt and Sherwood number on the experimental boundary conditions. A relative deviation between the measurement results and the model prediction below 1% for the sensible heat transfer is reported, while the prediction of the vapor-mass transfer rate exhibits an average relative deviation below 6%.