Droplet Evaporation in High Temperature Environments

Abstract

Axisymmetric-stagnation-point convective heat and mass transfer solutions are presented for water evaporating into dry air and into pure steam for free stream temperatures from 373K to 1450K and radiative to convective heat flux ratios from 0 to 2. Effects of (1) blowing (evaporation), (2) variable fluid properties, (3) interdiffusion (binary diffusion with nonequal heat capacities), and (4) radiation are all included. A simple correlation which fits these stagnation point solutions within 3 percent is presented. Whole droplet heat transfer is shown to behave much like stagnation-point heat transfer when the Reynolds number is on the order of 100. Blowing and other high temperature effects on whole droplet heat and mass transfer can be estimated with stagnation point solutions. The ratio of stagnation point solutions with and without high temperature effects should multiply no-blowing constant-fluid-properties whole-droplet heat transfer correlations as a correction factor. Such a corrected whole-droplet correlation compares favorably with experimental data in the literature.