Keywords

Condensation heat transfer, Superhydrophobic, Shear flow, Dropwise

Abstract

This study investigates heat transfer during dropwise condensation (DWC) on superhydrophobic (SH) surfaces in humid air shear flow, emphasizing the effect of increased drop mobility and the influence of surface micro/nanostructure on heat transfer rates. Experiments were conducted on smooth hydrophobic, microstructured SH, nanostructured carbon-infiltrated carbon nanotube (CICNT) surfaces, and two-tiered SH surfaces with both micro and nanostructures. Heat transfer rates were measured under humid air flow rates in the range of 2–4 CFM. Experimental results demonstrate that surfaces with nanostructure (including two-tiered structures) exhibit increased drop mobility and coalescence-induced drop jumping, enhancing drop removal rates and overall heat transfer performance as compared to smooth hydrophobic and microstructured surfaces. Additionally, the presence of nanostructures on two-tiered surfaces changes the preferred drop state from Wenzel for microstructured surfaces to Cassie-Baxter (CB) on two-tiered surfaces, further facilitating drop removal. A modified single drop heat transfer model for two-tiered SH surfaces was developed, accounting for the additional resistance introduced by the nanostructures. The single drop heat transfer model was combined with a drop-size distribution model to predict overall heat transfer rates. An exploration of surface parameters (e.g. nucleation site density and effective radius at coalescence) enabled successful prediction of condensation heat transfer rate trends, which were validated against experimental data. Heat transfer rates were found to increase with increasing solid fraction but decreasing surface pitch. A heat flux of up to 1 MW m-2 was observed on two-tiered SH surfaces. The findings have significant implications for industries relying on efficient condensation processes, such as water harvesting, desalination, and power generation.

Original Publication Citation

Humayun, S., Maynes, R. D., Crockett, J., and Iverson, B. D., 2026, "Influence of surface features on heat transfer during dropwise condensation over superhydrophobic surfaces in shear flow," International Journal of Heat and Mass Transfer, Vol. 254, p. 127689. DOI: 10.1016/j.ijheatmasstransfer.2025.127689

Document Type

Peer-Reviewed Article

Publication Date

2026

Publisher

International Journal of Heat and Mass Transfer

Language

English

College

Ira A. Fulton College of Engineering

Department

Mechanical Engineering

University Standing at Time of Publication

Full Professor

Download

Share

COinS