Simultaneous film evaporation and condensation on a two-directionally inclined surface

A theoretical analysis of the effects of inclination on the heat transfer rate during the simultaneous film evaporation on one side and film condensation on the other side of a solid flat plate is presented. The decrease of the evaporating film thickness due to the two-dimensional nature of the flow is relatively small. Hence, the corresponding increase in the overall transfer coefficient is practically insignificant. For a system in which the evaporating film is sustained by a vertically down-flowing liquid, the main effect of the inclination of the plane from the horizontal is due to the formation of an unwetted area. Some practical conclusions related to a bundle of conduits are suggested. In view of the conclusions, the extension of the flat plane analysis by sectional integration to inclined conduits is not warranted.