Evaporation from falling saline water films in laminar transitional flow

Abstract

Abstract An analytical and experimental study was made of the evaporation from pure and saline water films flowing down a heated vertical surface at Reynolds numbers between 160 and 600. Visual observation showed free surface evaporation. Film continuity was poor for pure water, but good for saline water, because of the influence of temperature and salinity on surface tension gradients. Evaporation rates were predicted by (1) a constant‐property boundary‐layer type of laminar analysis; (2) the constant‐property Dukler “eddy” treatment; and (3) a variable property laminar analysis that took into account the boiling point elevation due to salinity. The experimental evaporation rates could be correlated by dimensionless moduli arising out of the laminar analyses, but best quantitative agreement was found with the Dukler eddy treatment.