The petal effect of parahydrophobic surfaces offers low receding contact angles that promote effective boiling. (June 2019)

• Record Type: Journal Article
• Authors: Allred, Taylor P.; Weibel, Justin A.; Garimella, Suresh V.
• Is Part Of: International journal of heat and mass transfer. Volume 135(2019)
• Page Start: 403
• Page End: 412
• Publication Date: 2019-06
• Subjects: Parahydrophobic -- Hydrophobic -- Nucleate boiling -- Wettability -- Critical heat flux; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2019.02.002
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Investigation of boiling on hydrophobic surfaces with differing dynamic wetting behaviors. The receding contact angle governs the occurrence of critical heat flux. Visualizations show that bubble dynamics depend strongly on dynamic wetting behavior. Bubble dynamics agree with a bubble growth model based on the receding contact angle. Demonstrates the potential of parahydrophobic surfaces for use in boiling applications. Abstract: Despite extensive study of boiling processes and their widespread use in industry, critical interactions between the fluid and surface during boiling remain poorly understood. Simplistic, static descriptions of the contact angle are still relied upon to describe the effects of surface wettability on dynamic interfacial processes that govern boiling. This work demonstrates the critical role of the dynamic wettability characteristics of a surface on bubble growth dynamics and boiling performance. In spite of their superior nucleation behavior, hydrophobic surfaces have received little attention for boiling applications due to their typically premature transition from efficient nucleate boiling to inefficient film boiling. Evaluation of hydrophobic surfaces with high contact angle hysteresis reveals that the heat transfer efficacy of these surfaces can be exploited in boiling, so long as the receding contact angle of the surface is sufficiently small to mitigate vapor spreading and thereby extend the nucleate boiling regime. A new paradigm of textured boiling surfaces – parahydrophobic surfaces that exhibit the "petal effect" and mimic the wetting behavior of a rose petal – are shown to have untapped potential in boiling applications resulting from highly hydrophobic behavior coupled with low receding contact angles.