Enhanced water collection through a periodic array of tiny holes in dropwise condensation

• Published in: Applied physics letters 2018-02, Vol.112 (7)
• Main Authors: Song, Kyungjun, Kim, Gyeonghee, Oh, Sunjong, Lim, Hyuneui
• Format: Article
• Language: English
• Subjects: Applied physics; Coalescing; Collection; Condensation; Cooling systems; Dehumidification; Droplets; Free energy; Perforated plates; Solid surfaces
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5009403

This paper introduces a simple method of water collection by increasing the coalescence effects in dropwise condensation with the use of microscale holes. The tiny holes modified the surface free energy states of the droplets on the plate, yielding a surface free energy barrier between the flat solid surface and the holes. The spatial difference in the surface free energy of the droplets enabled the droplets to move toward the adjacent droplets, thus increasing the possibility of coalescence. The water collection experiments were performed using a Peltier-based cooling system at 2 °C inside a chamber at 30 °C and 70% humidity. The results demonstrated that the perforated plates without any additional treatment provided the water collection rate of up to 22.64 L/m2 day, which shows an increase of 30% compared to that demonstrated by the bare plate. By comparing the experimental results for the surface of filmwise condensation, it was proved that the dominant water collecting improvement results from the increased coalescence effects. This simple technique can enhance the performance of systems exposed to water condensation, including water collection, heat-transfer, and dehumidifying systems.