Dropwise steam condensation on various hydrophobic surfaces: Polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), and self-assembled micro/nano silver (SAMS). (October 2015)

• Record Type: Journal Article
• Authors: Zhang, Bong June; Kuok, Cheng; Kim, Kwang Jin; Hwang, Taeseon; Yoon, Hyungkee
• Is Part Of: International journal of heat and mass transfer. Volume 89(2015:Oct.)
• Page Start: 353
• Page End: 358
• Publication Date: 2015-10
• Subjects: Dropwise condensation (DWC) -- Hydrophobic -- Nanostructures -- Wetting -- Heat transfer -- Modeling -- Condensate dynamics -- Self-assembled nano coating; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2015.05.060
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: This study investigated several drop-wise condensation (DWC) promoters developed by coating techniques. Coatings were fabricated using surface treatments, with plain copper as a reference. Fabricated surfaces were examined by scanning electron microscope, contact angle measurements, and condensation heat transfer experiments. Heat fluxes were measured, and DWC population densities were recorded and compared. Results showed that surface morphologies and wetting behaviors directly affected drop sizes and population densities, demonstrating that superhydrophobic surfaces achieved by micro/nano morphologies may not increase condensation heat transfer. Decreases in heat fluxes due to increases in contact angle hysteresis increased drop sizes and hindered droplet renewal rates. Also, durability of performance of the self-assembled layer coating was demonstrated. Abstract: Drop-wise condensation (DWC) phenomena are closely related to hydrophobic promoters. In this study, various hydrophobic coatings such as PPS, PTFE, and self-assembled micro/nano silver were fabricated using surface treatments, with plain copper as a reference. Fabricated surfaces were examined by scanning electron microscope, contact angle measurements, and condensation heat transfer experiments. Heat fluxes were measured, and DWC population densities were recorded and compared. Results showed that surface morphologies and wetting behaviors directly affected drop sizes and population densities. When steady-state was reached, superhydrophobic surfaces showed poor condensation heat transfer compared to the self-assembled micro/nano silver deposited surface. It is assumed that contact angle hysteresis induced strong pinning along condensate periphery, which hindered rolling-off motion and droplet renewal rates. Also, durability of performance of the self-assembled layer coating was demonstrated.