CONDENSATION MASS TRANSFER IN UNSATURATED HUMID AIR INSIDE TUBULAR SOLAR STILL

A production model of a Tubular Solar Still based on a film-wise condensation theory that takes into account of thermal resistance in unsaturated humid air inside the still is developed in this study. The condensation coefficient due to thermal resistance is inversely proportional to the dry air pressure fraction. In the present model, the overall heat transfer coefficient between the humid air inside the still and the ambient air outside the still is used for the first time because the measurement of the ambient air temperature is easier to obtain than the inner surface temperature of the tubular cover. The analytical solution of this condensation theory could provide a good agreement with the observed production flux obtained from this laboratory experiment. Furthermore, in order to assess the model accuracy, the model prediction is compared with field experimental data and proves that the model can be used to precisely predict the production flux.