Influence of a Surfactant on Evaporation Intensity of Suspended Water Droplets

Experimental data have been presented on the evaporation rate of suspended droplets of both pure water and water containing ≈1.5 wt % surfactant, sodium dodecyl sulfate. Evaporation occurs in a convective flow of dry air, with its velocity and temperature being varied within ranges of U0 = 1–5 m/s and T0 = 20–80°C, respectively. The density of the mass flux from the surface of the surfactant-containing droplets is 2–3 times lower than that in the case of pure water. For droplets in a dry air flow, the change in their diameter can be described by a set of similarity criteria, and a generalized linear empirical dependence of the evaporation rate on thermodynamic parameters may be constructed for these droplets.