Dropwise evaporative cooling

A comprehensive model for the prediction of evaporative cooling of solid surfaces induced by the impingement of single water droplets is presented. The model predicts the droplet evaporation and the solid surface cooling for materials with thermal conductivity spanning over more than two orders of magnitude. The model accurately predicts the total evaporation time and it is further validated with transient surface temperature measurements obtained by infrared thermography. The predictions are in excellent agreement with the experimental data. The spatial and temporal heat flux distribution under the evaporating droplet is studied. The extent of the droplet evaporative cooling is quantified by introducing a novel concept defining the droplet radius of influence. A closed form solution predicting the radius of influence is derived and tested against the experimental data and the model predictions. An empirical correlation for the prediction of the evaporation time is also presented. Insight into the evaporative cooling phenomena is provided for materials with various thermal conductivity. The relevant parameters are identified and their influence on the phenomena is assessed