Experimental Study on Pool Boiling on Hydrophilic Micro/Nanotextured Surfaces with Hydrophobic Patterns

Abstract

Over the past decades, pool boiling on various wetting surfaces has been intensively investigated to enhance boiling heat transfer and critical heat flux. In this study, to enhance the two thermal performances simultaneously, we developed hydrophilic micro/nanotextured surfaces with hydrophobic patterns. Using a silicon substrate, well-arrayed microtextures and randomly arrayed nanotextures were fabricated hierarchically using micro/nanoelectromechanical system processes. The top of the microtextures was coated locally with hydrophobic characteristics using specific self-assembled monolayer coating methods. Based on experimental data, we postulate that the critical heat flux was enhanced by the capillary-induced flow between microtextures and that nanotextures with superhydrophilicity contribute to the delay of the critical heat flux by better wetting the dried area. Owing to the hydrophobicity at the top of the micropillars, the nucleate site density and boiling heat transfer increased.

Aluminum Micropillar Surfaces with Hierarchical Micro- and Nanoscale Features for Enhancement of Boiling Heat Transfer Coefficient and Critical Heat Flux

“…The high boiling performance of these surfaces is very favorable for utilization in high-energy applications where high performance and high energy dissipation are needed. [14,15,32,34,36,[40][41][42][43][44][45][64][65][66] and the surfaces presented in this study.…”

“…The data of the CHF and HTC shown in Figure 11 are summarized in Table S2, Supporting Information, Section S8. [14,15,34,36,[40][41][42][43][44][45][64][65][66] and the surfaces presented in this study.…”

“… Comparison of the pool boiling performance of literature-reported surfaces [ 14 , 15 , 32 , 34 , 36 , 40 , 41 , 42 , 43 , 44 , 45 , 64 , 65 , 66 ] and the surfaces presented in this study. …”

“…Cavities trapped vapor and improved bubble nucleation to enhance HTC, while the sidewalls of the microtube arrays provided CHF enhancement by increasing capillary wicking. Cho et al [ 43 ] reported the enhancement of CHF and boiling performance on silicon micro-nanotextured surfaces with mixed wettability. The CHF was improved up to 1900 kW m −2 by the fabricated nanostructure that enables better rewetting of the dried area, while improved boiling performance was achieved by imparting hydrophobicity at the top of the micropillars to increase the nucleation site density.…”

Boiling Heat Transfer Enhancement on Biphilic Surfaces

“…We also note that the aging problem is not considered in papers on biphilic surfaces, although it is fundamental, as for any micro/nanomodified surface [24,25]. Further improvement in boiling heat transfer on biphilic surfaces can be achieved by preliminary micro/nanostructuring [8,13,26]; in particular, laser methods are promising for micro/nanostructuring [21]. New interesting approaches to enhancing boiling heat transfer have also been proposed-for example, the simultaneous use of a biphilic surface and nanofluids.…”