Concepedia

Interfacial wicking dynamics and its impact on critical heat flux of boiling heat transfer

Beom Seok Kim, Hwanseong Lee, Sangwoo Shin, Geehong Choi, Hyung Hee Cho

Applied Physics Letters · 2014 · 167 citations · 32 references

TL;DR

Morphologically driven dynamic wickability determines the hydrodynamic status of solid‑liquid interfaces. The study shows that dynamic wicking supplies and propagates liquid across the interface, thereby controlling the critical heat flux during boiling. Wicking was quantitatively controlled by varying the characteristic lengths of hexagonally arranged sub‑micron nanopillars fabricated via nanosphere lithography and metal‑assisted chemical etching. Strong hemi‑wicking with a coefficient of 1.28 mm s⁻⁰·⁵ increased CHF by 164 % versus no wicking, and the developed wickability‑CHF model accurately predicts this improvement, outperforming classic wettability‑ and roughness‑based models.

Abstract

Morphologically driven dynamic wickability is essential for determining the hydrodynamic status of solid-liquid interface. We demonstrate that the dynamic wicking can play an integral role in supplying and propagating liquid through the interface, and govern the critical heat flux (CHF) against surface dry-out during boiling heat transfer. For the quantitative control of wicking, we manipulate the characteristic lengths of hexagonally arranged nanopillars within sub-micron range through nanosphere lithography combined with top-down metal-assisted chemical etching. Strong hemi-wicking over the manipulated interface (i.e., wicking coefficients) of 1.28 mm/s0.5 leads to 164% improvement of CHF compared to no wicking. As a theoretical guideline, our wickability-CHF model can make a perfect agreement with improved CHF, which cannot be predicted by the classic models pertaining to just wettability and roughness effects, independently.