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

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.

Effect of surface roughness on pool boiling heat transfer at a heated surface having moderate wettability

“…CHF variation with changing roughness on the metal surfaces has been reported to be approximately 10-20% in general [15,18]. In contrast, recent studies on CHF enhancement with silicon wafer surfaces show much larger augmentations with increasing roughness factor r, where roughness factor r is defined as the ratio of the actual contact area to the projected area [7,19,26,27]. Table 2 summarizes various studies regarding the effect of surface roughness on CHF for both metal surfaces and silicon wafer surfaces.…”

Critical heat flux triggering mechanism on micro-structured surfaces: Coalesced bubble departure frequency and liquid furnishing capability

“…At present, several surface modification techniques are available for enhancing CHF, such as nanofluid boiling, porous layer coating, enhancement of surface wettability, and micro/nanostructured surface fabrication. However, the related models and theories for explicating the CHF phenomenon have been biased in favor of macroscopic (vapor-liquid hydrodynamics) or microscopic physics, such as solid-liquid adhesion force [9], capillary wicking [10][11][12], and liquid wetting characteristics [13][14][15]. Additionally, the effects of thermal conduction on the surface were presented as the key mechanism by some researchers [16,17].…”

Mi̇kro Boyutta Yapilandirilmiş Bi̇r Yüzeyde Havuz Kaynama Isi Transferi̇ni̇n Deneysel İncelenmesi̇

“…Araştırmacılar tarafından yapılan çalışmalarda, kaynama ısı transferini artırmak için ısıtma yüzeyinde titreşim, akışkan içerisinde ultrasonik titreşim ve karmaşık geometrili, pürüzlü veya poroz yapılı yüzeyler gibi çeşitli aktif ve pasif teknikler kullanılmıştır [1]. Araştırmacılar, etkin yüzey alanı, aktif çekirdek site sayısı ve düşük kızma farkı gibi parametrelerin iyileşmesi ile ısı transfer performansında önemli artışlar rapor etmişlerdir [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Günümüzde, mikro ve nano boyutlarda malzeme üretim tekniklerindeki gelişmeler sayesinde, ısı transferini önemli ölçüde artıran yüzeylerin üretimi * Corresponding author / Sorumlu yazar.…”

“…Kandlikar [11], birkaç yüz mikron boyutunda yapılandırılmış yüzeylerin kaynama süresince ısı transferini artırıcı bir kabarcık hareketini tetiklediğini rapor etmiştir. Son yıllarda yapılan birkaç çalışmada ise [12][13][14], mikro/nano yapılı yüzeylerde kılcallık etkisindeki belirgin artışın CHF değerini artıracağı vurgulanmıştır.…”