Differential and average approaches to Rose and Mei dropwise condensation models

Two well-known models for drop-size distribution function during dropwise condensation -called Rose model and Mei model- were examined in two different aspects, average and differential point of view. It has been proved that these two models are able to describe the relation between droplets size and distribution function at each time step. The goal of this research is to investigate how these models can predict the relation between average distribution function (Nave) and average radius (rave) of droplets during a complete procedure of dropwise condensation and the relation between differential distribution function (dN/dr ) and drops radius (r) at each time step. The empirical parameters are drop size distribution exponent (n) and fractal dimension (df) in Rose model and Mei model respectively. At first these two parameters were calculated based on the experimental data and then the validity of these calculations for our computer simulation was investigated. It was concluded that Rose method fits the results of differential distribution function with exponent n between 0.33 and 0.35, and average distribution function with n of around 0.38. The Mei model also can describe both differential and average results of simulation and experiments with fractal dimension of 1.79