Augmentation of Heat Transfer in a Laminar External Gas Boundary Layer by the Vaporization of Suspended Droplets

Abstract

A theory is developed for the restricted regime of two-phase flow wherein droplets suspended in a gas stream penetrate the boundary layer and vaporize without deposition. The equations of motion of the droplets are derived taking into account Stokes’ drag, buoyancy, and gravity forces. Superimposed free stream turbulence propels a fraction of the droplets into the boundary layer. Using these results a two-region model is developed for determining the heat transfer rate. The application of the theory is illustrated by calculating several quantities of practical interest for the finned surface of a dry cooling tower.