Influence of Surface Wettability on Bubble Formation and Motion

Abstract

Bubble dynamics plays an important role in boiling heat transfer, and surface wettability affects bubble behaviors. In the present work, the effects of surface superhydrophilicity (SHI) and superhydrophobicity (SHO) on bubble dynamics are experimentally studied by observing the formation and motion behaviors of air bubbles and vapor bubbles on varied surfaces. For air bubbles to better mimic vapor bubbles, the air bubbles are introduced in a water pool by injecting airflow from a through hole of the surface. Air bubble tests are first conducted on homogeneous SHO and SHI surfaces, respectively. It is observed that surface wettability significantly affects the bubble size and departure frequency. To discover the dynamic behaviors of a bubble under both SHI and SHO, a biphilic surface with SHI and SHO areas is fabricated, and air bubbles are injected right on the biphilic border between the two areas. It is observed the wettability contrast significantly displaces the air bubbles, which spread only onto the SHO area. The biphilic surface is fabricated for the pool boiling test. Vapor bubbles are observed at different stages of the nucleate boiling, showing surface effects similar to the observations of air bubbles. Not only does this study present the influence of surface wettability on air and vapor bubble behaviors but also it provides useful implications for understanding and optimizing the biphilic surface design for enhancing boiling heat transfer.

Superbiphilic Laser‐Microengineered Surfaces with A Self‐Assembled Monolayer Coating for Exceptional Boiling Performance

“…Studies range from enhancements based on boiling fluid modification, [ 9,10 ] such as with the addition of nanoparticles (i.e., nanofluids) [ 11,12 ] or with mixtures of different surface tensions, [ 13,14 ] to studies focusing on surface modification, [ 15,16 ] with an emphasis on changing the surface topography [ 17,18 ] and morphology [ 19,20 ] alongside with its wetting behavior. [ 21,22 ]…”

“…Studies range from enhancements based on boiling fluid modification, [9,10] such as with the addition of nanoparticles (i.e., nanofluids) [11,12] or with mixtures of different surface tensions, [13,14] to studies focusing on surface modification, [15,16] with an emphasis on changing the surface topography [17,18] and morphology [19,20] alongside with its wetting behavior. [21,22] In recent years, various technologies have been explored to tailor the surface topography and morphology to improve boiling performance. [1,23] The fabrication of micro/nanostructures, e.g., cavities, pores, and irregularities on surfaces, can generally enhance bubble nucleation and rewetting with liquid, thus improving boiling performance.…”

Bubble Management for Electrolytic Water Splitting by Surface Engineering: A Review

“…Consequently, the electrochemical reaction area and surface morphology are crucial to the optimization of bubble nucleation. 41,42 Bubbles grow gradually on the electrode surface after nucleation 43,44 and successively experience the rapid growth mode (inertia-controlled growth) and the slow growth mode (diffusive growth). 6 The growth rate of bubbles is mainly determined by the formation rate of hydrogen molecules and the coalescence behavior between bubbles and is influenced by a series of parameters such as current density, electrocatalytic area, system temperature, and liquid−substrate contact angle.…”

Heat Transfer Characteristics of Pool Boiling with Scalable Plasma-Sprayed Aluminum Coatings

“…Heat enhancement in pool boiling is required in various industrial and household applications like thermal power generation, space industry, refrigeration, air conditioning, chemical processing industry, electronic device cooling, and several others. Over the last few decades, substantial research works have investigated various surface modification strategies for improving pool boiling thermal performance. − …”