Experimental analysis of drop size distribution and nucleation site density during dropwise condensation from humid air flow

Abstract Condensation of the water vapor present in air is a heat and mass transfer process encountered many applications as humid dehumidification harvesting. Depending on wettability characteristics surface, condensation can take place filmwise mode or dropwise with formation discrete liquid droplets over condensing surface. While (DWC) pure steam was found to promote considerable enhancement compared condensation, when dealing DWC more investigation needed. Modeling from requires calculation flow rate through single droplet determination drop-size distribution. The exchanged depends resistances, while distribution also affected by nucleation site density mobility. Therefore, better understand phenomenon for validation models, it necessary measure flux (total latent), population density. In work, tests are performed two square (40 mm x 40 mm) aluminum samples that display different wettability. experimental apparatus consists closed loop main components: environmental chamber test chamber. conditioned then flows inside section where condensed vertical metallic sample. Two variable speed fans used circulate air. designed measurements simultaneous visualization process. As peculiar characteristic technique, all assembly suspended high precision balance allowing precise measurement condensate. effect surface during investigated. Time-lapse videos acquired at magnifications. By using homemade MATLAB ® program detection, recorded images analysed both drop size (small large population) sites