Simulation of dropwise condensation on a superhydrophobic inclined substrate

Mathematical model and a simulator are developed to predict dropwise condensation on superhydrophobic inclined surfaces. The model is established by considering the vapor-liquid interfacial resistance, the resistance due to the conduction through the drop itself, the resistance from the coating layer, and the resistance due to the curvature of the drop for single drop heat transfer model with drop size distribution. A population balance model is adapted to develop a drop distribution function for the small drops that grow by direct condensation. Drop size distribution for large drops that grow mainly by coalescence is obtained from a well known empirical equation. The evidence obtained suggests that both the single droplet heat transfer and drop distribution are significantly affected by the contact angle and contact area. More specifically, the model results indicate that a high drop contact angle leads to enhancing condensation heat transfer. Hydrophobicity surfaces produces high contact angles, causes a reduction in the size of drops allowing space for more small drops which leads to increase in heat transfer coefficient. The simulator is developed using VB.Net which simulate the drop wise condensation on hydrophobic and superhydrophobic surfaces and results are compared with experimental data.