Marangoni effect on pool boiling heat transfer enhancement of self-rewetting fluid

Hu, Yi; Chen, Sixu; Huang, Jin; Song, Mengjie

doi:10.1016/j.ijheatmasstransfer.2018.08.003

Cited by 29 publications

(8 citation statements)

References 29 publications

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“…Although negligible in the boiling of single-component fluids [52], Marangoni flow significantly affects the boiling performance in dilute mixtures of alcohols (with four and more carbon atoms) in water [53,54]. These mixtures were named self-rewetting fluids (SRFs), as solutal Marangoni flow is expected to be further enhanced by thermal Marangoni flow, and the inflow of colder liquid spontaneously rewets hot places during boiling due to surface tension gradients induced by temperature inhomogeneities inside the boiling liquid [9,52,54].…”

Section: Self-rewetting Fluidsmentioning

confidence: 99%

Hydrophilic and Hydrophobic Nanostructured Copper Surfaces for Efficient Pool Boiling Heat Transfer with Water, Water/Butanol Mixtures and Novec 649

et al. 2021

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Increasing heat dissipation requirements of small and miniature devices demands advanced cooling methods, such as application of immersion cooling via boiling heat transfer. In this study, functionalized copper surfaces for enhanced heat transfer are developed and evaluated. Samples are functionalized using a chemical oxidation treatment with subsequent hydrophobization of selected surfaces with a fluorinated silane. Pool boiling tests with water, water/1-butanol mixture with self-rewetting properties and a novel dielectric fluid with low GWP (Novec™ 649) are conducted to evaluate the boiling performance of individual surfaces. The results show that hydrophobized functionalized surfaces covered by microcavities with diameters between 40 nm and 2 µm exhibit increased heat transfer coefficient (HTC; enhancements up to 120%) and critical heat flux (CHF; enhancements up to 64%) values in comparison with the untreated reference surface, complemented by favorable fabrication repeatability. Positive surface stability is observed in contact with water, while both the self-rewetting fluids and Novec™ 649 gradually degrade the boiling performance and in some cases also the surface itself. The use of water/1-butanol mixtures in particular results in surface chemistry and morphology changes, as observed using SEM imaging and Raman spectroscopy. This seems to be neglected in the available literature and should be focused on in further studies.

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Section: Self-rewetting Fluidsmentioning

confidence: 99%

Hydrophilic and Hydrophobic Nanostructured Copper Surfaces for Efficient Pool Boiling Heat Transfer with Water, Water/Butanol Mixtures and Novec 649

et al. 2021

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“…In single-component fluids, the thermal Marangoni flow is negligible under common conditions [45]. For the saturated and even for the subcooled boiling of self-rewetting mixtures under common conditions, the effect of the thermal Marangoni flow was found to be insignificant relative to the intensity of the solutal Marangoni flow [45,46]. Hu et al [45] used thermal and solutal Marangoni numbers to estimate the intensity of both Marangoni flows.…”

Section: Self-rewetting Fluidsmentioning

confidence: 99%

“…For the saturated and even for the subcooled boiling of self-rewetting mixtures under common conditions, the effect of the thermal Marangoni flow was found to be insignificant relative to the intensity of the solutal Marangoni flow [45,46]. Hu et al [45] used thermal and solutal Marangoni numbers to estimate the intensity of both Marangoni flows. They obtained thermal Marangoni numbers, which were two orders of magnitude lower compared with the solutal Marangoni numbers.…”

Section: Self-rewetting Fluidsmentioning

confidence: 99%

Pool Boiling Performance of Water and Self-Rewetting Fluids on Hybrid Functionalized Aluminum Surfaces

et al. 2021

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The boiling performance of functionalized hybrid aluminum surfaces was experimentally investigated for water and self-rewetting mixtures of water and 1-butanol. Firstly, microstructured surfaces were produced via chemical etching in hydrochloric acid and the effect of the etching time on the surface morphology was evaluated. An etching time of 5 min was found to result in pitting corrosion and produced weakly hydrophilic microstructured surfaces with many microcavities. Observed cavity-mouth diameters between 3.6 and 32 μm are optimal for efficient nucleation and provided a superior boiling performance. Longer etching times of 10 and 15 min resulted in uniform corrosion and produced superhydrophilic surfaces with a micropeak structure, which lacked microcavities for efficient nucleation. In the second stage, hybrid surfaces combining lower surface energy and a modified surface microstructure were created by hydrophobization of etched aluminum surfaces using a silane agent. Hydrophobized surfaces were found to improve boiling heat transfer and their boiling curves exhibited a significantly lower superheat. Significant heat transfer enhancement was observed for hybrid microcavity surfaces with a low surface energy. These surfaces provided an early transition into nucleate boiling and promoted bubble nucleation. For a hydrophobized microcavity surface, heat transfer coefficients of up to 305 kW m−2 K−1 were recorded and an enhancement of 488% relative to the untreated reference surface was observed. The boiling of self-rewetting fluids on functionalized surfaces was also investigated, but a synergistic effect of developed surfaces and a self-rewetting working fluid was not observed. An improved critical heat flux was only obtained for the untreated surface, while a lower critical heat flux and lower heat transfer coefficients were measured on functionalized surfaces, whose properties were already tailored to promote nucleate boiling.

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“…Thermal Marangoni convection [ 50,51 ] originates from heating‐induced surface tension gradient. The surface tension gradient drives hot suspension with a low surface tension close to the substrate to flow toward the cold region with a high surface tension (Figure 2a).…”

Section: Figurementioning

confidence: 99%

“…Solutal Marangoni convection [ 50,51 ] also originates from the heating‐induced surface‐tension gradient. The suspension used in the assembly contains two solvents: water (low volatility and high surface tension) and IPA (high volatility and low surface tension).…”

Section: Figurementioning

confidence: 99%

High‐Rate Printing of Micro/Nanoscale Patterns Using Interfacial Convective Assembly

et al. 2020

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Electric-field-directed assembly [31,32] uses electrophoretic and dielectrophoretic forces to direct nanoelements. Although electric-field-directed assembly demonstrates high throughput, high scalability, and high resolution in assembling various nanomaterials, conductive substrates are required to generate electric field, which limits potential applications of printed structures in electronic devices. Fluidicflow-directed assembly such as convective [33][34][35] and capillary [36][37][38] assembly utilizes solvent evaporation-induced convective flow to guide and position nanoelements. Unlike electric-field-directed assembly, fluidic-flow-directed assembly is applicable to all kinds of substrates (both insulating and conductive). However, it takes hours to assemble over centimetersized substrates. Therefore, the scalability and throughput of this assembly process is a major challenge. Photothermally directed assembly uses photothermaleffect-induced Rayleigh-Benard [39] and/or Marangoni [40][41][42] convective flow to direct assembly. Similar to fluidic-flow-directed assembly, photothermally directed assembly suffers from scalability and throughput issues due to its serial processing nature. In addition, photothermally directed assembly has a limited resolution of micro or sub-micro scale. [43,44] Therefore, the development of a broadly applicable, highly scalable, high throughput, and high resolution printing technique is highly desirable.Here, we report a novel fluidic-flow-directed assembly technique, interfacial convective assembly, to rapidly assemble particles in pattern areas on any substrates. In the interfacial convective assembly, a patterned substrate is initially sonicated in isopropyl alcohol (IPA) using a bath type sonicator for a few seconds. With a low surface tension, IPA helps wet as well as remove trapped air in the patterned structures. After sonication, the substrate is removed from the IPA bath, leaving a thin IPA film on the substrate. Afterward, 50 µL aqueous particle suspension is drop casted on the IPA film. The particle suspension immediately mixes with the IPA film, resulting a suspension with ≈20 wt% IPA. Then, a glass slide is covered on the suspension, creating a confined environment with the substrate via a 300 µm thick spacer (Figure 1a). Finally, the setup is placed onto a hot plate with preheated temperatures between 40 and 75 °C. The substrate is heated up, inducing a convective flow. Due to the convective flow, particles are carried toward Printing of electronics has been receiving increasing attention from academia and industry over the recent years. However, commonly used printing techniques have limited resolution of micro-or sub-microscale. Here, a directed-assembly-based printing technique, interfacial convective assembly, is reported, which utilizes a substrate-heating-induced solutal Marangoni convective flow to drive particles toward patterned substrates and then uses van der Waals interactions as well as geometrical confinement to trap the particles in the pattern area...

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Marangoni effect on pool boiling heat transfer enhancement of self-rewetting fluid

Cited by 29 publications

References 29 publications

Hydrophilic and Hydrophobic Nanostructured Copper Surfaces for Efficient Pool Boiling Heat Transfer with Water, Water/Butanol Mixtures and Novec 649

Hydrophilic and Hydrophobic Nanostructured Copper Surfaces for Efficient Pool Boiling Heat Transfer with Water, Water/Butanol Mixtures and Novec 649

Pool Boiling Performance of Water and Self-Rewetting Fluids on Hybrid Functionalized Aluminum Surfaces

High‐Rate Printing of Micro/Nanoscale Patterns Using Interfacial Convective Assembly

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