Boiling heat transfer and critical heat flux evaluation of the pool boiling on micro structured surface

Kim, Seol Ha; Lee, Gi Cheol; Kang, Jee-Hyun; Moriyama, Kiyofumi; Kim, Moo Hwan; Park, Hyun Sun

doi:10.1016/j.ijheatmasstransfer.2015.07.120

Cited by 156 publications

(45 citation statements)

References 21 publications

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“…In the present work, the Dhir-Liaw model [25] that accounts for the effect of the contact angle on CHF is used to calculate CHF,f q . The apparent contact angle on structured surfaces is calculated using the equilibrium contact angle at room temperature [26], and is substituted into q as a function of the characteristic wicking rate w,ch  for experimental data from the literature on pool boiling on square micropillar arrays [2,3,7,11]. The wetting properties and geometric dimensions of the surfaces used in these references are summarized in Section S2 of the Supplementary Material.…”

Section: Model Formulationmentioning

confidence: 99%

“…The predictions from the CHF model developed above are compared with experimental data in the literature for water boiling on square micropillar arrays [2,3,7,11] in Figure 8. The modelpredicted CHF is calculated using the micropillar geometry, wettability, and material properties reported in [2,3,7,11], as listed in Section S2 of the Supplementary Material. A roughness factor of s 2 r  = is used to account for the roughness on the side wall of the micropillars fabricated with deep reaction ion etching (DRIE) [16].…”

Section: Comparison With Experimental Studiesmentioning

confidence: 99%

“…A roughness factor of s 2 r  = is used to account for the roughness on the side wall of the micropillars fabricated with deep reaction ion etching (DRIE) [16]. This comparison includes experimental data for water boiling on various micropillar arrays having different surface coatings, including bare silicon (no coating) [7], silicon oxide [3,11], and gold [2]. The water contact angle at the boiling point (100 °C at atmospheric pressure) is estimated following Chu et al's analysis of the effect of temperature on the contact angle [38].…”

Section: Comparison With Experimental Studiesmentioning

confidence: 99%

“…Recent experimental studies [2,3,[5][6][7][8][9][10][11][12][13][14][15][16][17][18] have shown that using micro-/nano-structured surfaces can enhance CHF well above Zuber's limit. A variety of mechanisms have been proposed to explain the structure-induced CHF enhancement, including increased three-phase contact line length [11,16], microconvection around the bubble [19], increased departure frequency of coalesced bubbles [3], and liquid rewetting via capillary wicking [2,3,5,7,8,11,13,14]. Among these mechanisms, capillary wicking has been the most widely agreed upon, with strong support from experimental data [2,5,10,17].…”

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confidence: 99%

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A coupled wicking and evaporation model for prediction of pool boiling critical heat flux on structured surfaces

Weibel

Garimella

2019

International Journal of Heat and Mass Transfer

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Boiling is an effective heat transfer mechanism that is central to a variety of industrial processes including electronic systems, power plants, and nuclear reactors. Micro-/nanostructured surfaces have been demonstrated to significantly enhance the critical heat flux (CHF) during pool boiling, but there is no consensus on how to predict the structure-induced CHF enhancement. In this study, we develop an analytical model that takes into consideration key mechanisms that govern CHF during pool boiling on structured surfaces, namely, capillary wicking and evaporation of the liquid layer underneath the bubble. The model extends existing wicking-based CHF theories by introducing the competing evaporation mechanism. The model reveals a wicking-limited regime where CHF increases monotonically with the wicking flux, and an evaporation-limited regime where additional increases in the wicking flux do not significantly affect CHF. The model predictions are shown to agree with experimental CHF data from the literature for boiling of water on surfaces structured with square micropillar arrays. A parametric study is performed for such micropillared surfaces and has identified the optimal structure based on the competition between wicking and evaporation, capillary pressure and viscous resistance, and conduction and liquid-vapor interfacial resistance.

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Section: Model Formulationmentioning

confidence: 99%

Section: Comparison With Experimental Studiesmentioning

confidence: 99%

Section: Comparison With Experimental Studiesmentioning

confidence: 99%

mentioning

confidence: 99%

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A coupled wicking and evaporation model for prediction of pool boiling critical heat flux on structured surfaces

Weibel

Garimella

2019

International Journal of Heat and Mass Transfer

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“…A number of studies have dealt with the enhancement of boiling heat transfer from electronic components by the use of surface microstructures [13]. In the work of Kim et al [14] the effectiveness of micro-structured surfaces (circular micropillar arrays with height, diameter and gap between 5-40 μm) in enhancing the achieved HTCs and CHFs is investigated. It is shown that both the boiling heat transfer and critical heat flux can be enhanced (up to +310% for CHF and +350% for HTC) by optimising the geometrical characteristics of the micro-pillar arrays.…”

Section: Introductionmentioning

confidence: 99%

Pool Boiling Versus Surface Wettability Characteristics

Villa

Georgoulas

Marengo³

et al. 2016

Proceedings of the World Congress on Momentum, Heat and Mass Transfer

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-The present paper reports results of pool boiling experiments on surfaces with different wettabilities. The main aim is to identify and quantify the difference in pool boiling characteristics (Onset of Nucleate Boiling-ONB, bubble detachment diameter and time) between Hydrophilic Surfaces (HPS) and Super-Hydrophobic Surfaces (SHS). A combined sample (SHS_D) with an inner SHS part and an outer HPS part is also tested, which clearly shows that the Super-Hydrophobic surface is a preferential area for the ONB, and allows to control the bubbling position. It is found that not only the ONB, but also the bubble growth and detachment characteristics are highly influenced by the wettability of the heated surface. The analysis of the experimental results reveals that SHSs require a lower wall-superheat for ONB to occur. Moreover, in SHSs higher bubble departure times as well as higher equivalent bubble detachment diameters are encountered. The vapour phase tends to stick stronger on a SHS than on a HPS, showing a tendency to create a vapour film. Furthermore, using a post processing method developed in MATLAB, the apparent contact angle at various successive time instances is extracted from the experimental snapshots for the cases of the HPS and the SHS_D. Finally, the capability of a previously verified, enhanced, CFD-based, VOF numerical model [1-3] to capture adequately the apparent triple line contact angle, from the nucleation up to the departure of an isolated bubble from the heated surface, is checked for one of the considered superheats for a HPS case.

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Three‐Tier Hierarchical Structures for Extreme Pool Boiling Heat Transfer Performance

et al. 2022

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The heat transfer coefficient (HTC, h) and critical heat flux (CHF, q″ CHF ) are two major parameters that quantify boiling performance. The HTC describes the efficiency of boiling heat transfer, defined as the ratio of heat flux (q″) to the wall superheat (ΔT w ), that is, h = q″/ΔT w . Here ΔT w is the temperature difference between the boiling surface and the saturated liquid. In the nucleate boiling regime, the heat flux increases with the wall superheat. However, when the heat flux is sufficiently high, excessive vapor bubbles nucleated on the boiling surface prevent the liquid from rewetting the surface and, in turn, form an insulating vapor film over the surface. This vapor film becomes a thermal barrier that leads to a drastic increase in wall superheat and burnout of a boiling system. This transition from nucleate boiling to film boiling is known as the boiling crisis, where the maximum heat flux is CHF. Enhancing CHF, therefore, can either enable larger safety margins or extend the operational heat flux range for boiling systems. [5] Recent efforts to enhance boiling heat transfer have focused on engineering the working fluid or surface properties. [6] In particular, engineering surface structures have received greater attention owing to the constraints on chemical compatibility or operational conditions which can limit the choice of the working fluid. Representative examples of surface structures that effectively enhance CHF are known to be hemi-wicking surfaces such as micropillars and nanowires. [7] These structures enhance CHF by harnessing thin-film evaporation around pillars and capillary-fed wicking through the structures. [8] Surfaces with microcavities, on the other hand, have shown improved HTC by trapping vapor embryos that promote nucleation. [9] Recently, a combination of microtube and micropillar structures referred to as tube-clusters in pillars (TIP), has shown the ability to tune the HTC and CHF by controlling bubble coalescence while maintaining capillary wicking. [10] Despite the controllability, achieving extreme enhancement of HTC and CHF simultaneously remains challenging due to the intrinsic tradeoff between HTC and CHF associated with nucleation-site density. For example, high nucleation-site density may increase HTC but decrease CHF because extensive bubble coalescence hinders the capillary wicking performance, while the reduced number of nucleation sites will limit the HTC enhancement.Boiling is an effective energy-transfer process with substantial utility in energy applications. Boiling performance is described mainly by the heat-transfer coefficient (HTC) and critical heat flux (CHF). Recent efforts for the simultaneous enhancement of HTC and CHF have been limited by an intrinsic trade-off between them-HTC enhancement requires high nucleation-site density, which can increase bubble coalescence resulting in limited CHF enhancement. In this work, this trade-off is overcome by designing three-tier hierarchical structures. The bubble coalescence is minimized to enhance the ...

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Boiling heat transfer and critical heat flux evaluation of the pool boiling on micro structured surface

Cited by 156 publications

References 21 publications

A coupled wicking and evaporation model for prediction of pool boiling critical heat flux on structured surfaces

A coupled wicking and evaporation model for prediction of pool boiling critical heat flux on structured surfaces

Pool Boiling Versus Surface Wettability Characteristics

Three‐Tier Hierarchical Structures for Extreme Pool Boiling Heat Transfer Performance

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