Large-scale Generation of Patterned Bubble Arrays on Printed Bi-functional Boiling Surfaces

Abstract

Bubble nucleation control, growth and departure dynamics is important in understanding boiling phenomena and enhancing nucleate boiling heat transfer performance. We report a novel bi-functional heterogeneous surface structure that is capable of tuning bubble nucleation, growth and departure dynamics. For the fabrication of the surface, hydrophobic polymer dot arrays are first printed on a substrate, followed by hydrophilic ZnO nanostructure deposition via microreactor-assisted nanomaterial deposition (MAND) processing. Wettability contrast between the hydrophobic polymer dot arrays and aqueous ZnO solution allows for the fabrication of heterogeneous surfaces with distinct wettability regions. Heterogeneous surfaces with various configurations were fabricated and their bubble dynamics were examined at elevated heat flux, revealing various nucleate boiling phenomena. In particular, aligned and patterned bubbles with a tunable departure frequency and diameter were demonstrated in a boiling experiment for the first time. Taking advantage of our fabrication method, a 6 inch wafer size heterogeneous surface was prepared. Pool boiling experiments were also performed to demonstrate a heat flux enhancement up to 3X at the same surface superheat using bi-functional surfaces, compared to a bare stainless steel surface.

Nanosecond laser texturing of uniformly and non-uniformly wettable micro structured metal surfaces for enhanced boiling heat transfer

“…However, because of the increased wettability, hydrophilic surfaces require larger superheat for nucleate boiling to occur and do not necessarily provide an enhanced heat transfer coefficient at low heat fluxes [3]. For further enhancements, several authors already suggested simultaneous implementation of hydrophobic and hydrophilic features on a single surface to produce a so called biphilic surface [3,6,7,9].…”

Bubbles nucleating on superhydrophobic micropillar arrays under flow

“…12 Various attempts were made in order to control nucleation of bubbles at the solid/liquid interface including the use of ultrasonic waves, 8 surface cavities, 9 temperature and surfactants, 1 and biphilic surfaces (chemically patterned hydrophobic/hydrophilic surfaces). 13 These attempts, however, require high pressures, the use of distinctive chemical moieties or temperature regulation. As many natural and synthetic surfaces are structured, 14,15 it is of high interest to use the potency of morphology for controlling heterogeneous nucleation.…”

Mechanism of gushing induction by carbon dioxide transfer activator

“…On the other side of the temperature spectrum a solid wall of a container accelerates the boiling of the liquid, but the adhered vapour bubbles block the heat transfer from the heated surface to the liquid. Release of the bubbles from the surface can be accelerated by coating the solid surface with hydrophobic and hydrophilic particles .…”