How does surface wettability influence nucleate boiling?

Abstract

Although the boiling process has been a major subject of research for several decades, its physics still remain unclear and require further investigation. This study aims at highlighting the effects of surface wettability on pool boiling heat transfer. Nanocoating techniques were used to vary the water contact angle from 20 • to 110 • by modifying nanoscale surface topography and chemistry. The experimental results obtained disagree with the predictions of the classical models. A new approach of nucleation mechanism is established to clarify the nexus between the surface wettability and the nucleate boiling heat transfer. In this approach, we introduce the concept of macro-and micro-contact angles to explain the observed phenomenon. To cite this article: H.T.

Thermohydrodynamics of boiling in a van der Waals fluid

“…In engineering, boiling heat transfer is a common method of heat transfer in thermal power plants, conventional and nuclear alike, and is thus an indispensable part of electricity production. Efficiency of heat transfer by boiling is limited by the creation of a vapor film at the hot surface when heat throughput is too high [1][2][3][4]. This effect is generally called critical heat flux, boiling crisis, or dryout.…”

Wettability Effects on Heat Transfer

“…16) for the departure diameter considering the wettability effects using an energy factor, as the ratio of the energy needed to form a bubble with a contact angle to need to form a homogeneous bubble with the same diameter, which is proposed by Bankoff (1967) (Phan et al, 2009a) www.intechopen.com…”

“…However, the higher heat flux region is governed by a nucleate boiling, in which the nonwetting surface represents a larger bubble generation due to a higher nucleation cite density (Eddington & Kenning, 1979). Phan et al (2009aPhan et al ( , 2009b investigated the wettability effects on a nucleate boiling using various materials deposited on surfaces. In the hydrophobic surface, no bubble departure was noticed and the heat transfer was unstable when the bubbles stayed on the heating surface.…”

“…23. Heat transfer coefficient versus the contact angles (Phan et al, 2009a) Except coating methods, a typical way to change the contact angle is the use of surfactant solutions. However, this method changes the surface wettability, the liquid surface tension, and the viscosity simultaneously.…”

A continuum approach to study vapor vaporization within textured surface

“…Surface characteristics are known to be a critical factor in determining the efficiency of heat transfer. [4][5][6][7][8][9][10][11] Utilizing optimal surfaces can increase energy efficiency and have a profound impact on industrial applications. For example, superhydrophilic surfaces have been designed to promote wetting and enhance the heat transfer efficiency by changing the surface interfacial chemistry property or altering the surface texture spacing and geometry.…”