Computational fluid dynamics investigation of dropwise condensation heat transfer through a single droplet on Wenzel structures

Abstract

Characterizing the behaviors of heat transfer rate of a droplet on rough surface to create hydrophobic surface is an important step toward efficient utilization of dropwise condensation (DWC). This work presents a numerical examination on the influence of surface roughness considering Wenzel structures on DWC heat transfer. The simulation of the liquid droplet has been done by utilizing the Surface Evolver (SE) software. The governing equations were discretized according to the finite volume method (FVM) utilizing the computational fluid dynamics (CFD) software (ANSYS-FLUENT). For various roughness indexes, the impacts of different saturation temperatures and droplet volumes on the average heat flux were evaluated. Also, the outcomes extracted from the model were validated with attainable data in the literature and a good agreement was achieved. The outcomes imply that average heat flux would decrease for a Wenzel structure with maximum roughness index (ri=0.6) compared to a smooth surface at θ=160° about 32.3% considering water as a liquid droplet with (Tsat=313K, Pr=4.32). Moreover, it was found that the average heat flux augments with a rise in the droplet saturation temperature also a decrease in the droplet volume. Additionally, the increase of Ma and Re numbers, would result in the increase of average heat flux.