Knowledge Management System Of Guangzhou Institute of Energy Conversion, CAS
| Effect of channel surface wettability and temperature gradients on the boiling flow pattern in a single microchannel | |
| Zhang, Wei1; Liu, Guohua1; Xu, Jinliang1; Yang, Yongping2 | |
| 2009-05-01 | |
| Source Publication | JOURNAL OF MICROMECHANICS AND MICROENGINEERING
 |
| Volume | 19Issue:5Pages:055012 |
| Corresponding Author | xujl@ms.giec.ac.cn |
| Abstract | The objective of this paper is to investigate the effects of channel surface wettability and temperature gradients on the boiling flow pattern in a single microchannel. The test section consists of a bottom silicon substrate bonded with a top glass cover. Three consecutive parts of an inlet fluid plenum, a central microchannel and an outlet fluid plenum were etched in the silicon substrate. The central microchannel had a width of 800 mu m and a depth of 30 mu m. Acetone liquid was used as the working fluid. High outlet vapor qualities were dealt with here. The flow pattern consists of a fluid triangle (shrinkage of the liquid films) and a connected long liquid rivulet, which is generated in the central microchannel in the timescale of milliseconds. The peculiar flow pattern is formed due to the following reasons: (1) the liquid rivulet tends to have a large contact area with the top hydrophilic channel surface of the glass cover, but a smaller contact area with the bottom silicon hydrophobic surface. (2) The temperature gradient in the chip width direction at the top channel surface of the glass cover not only causes the shrinkage of the liquid films in the central microchannel upstream, but also attracts the liquid rivulet populated near the microchannel centerline. (3) The zigzag pattern is formed due to the competition between the evaporation momentum forces at the vapor-liquid interfaces and the force due to the Marangoni effect. The former causes the rivulet to deviate from the channel centerline and the latter draws the rivulet toward the channel centerline. (4) The temperature gradient along the flow direction in the central microchannel downstream causes the breakup of the rivulet to form isolated droplets there. (5) Liquid stripes inside the upstream fluid triangle were caused by the small capillary number of the liquid film, at which the large surface tension force relative to the viscous force tends to populate the liquid film locally on the top glass cover surface. |
| Subtype | Article |
| Other Abstract | The objective of this paper is to investigate the effects of channel surface wettability and temperature gradients on the boiling flow pattern in a single microchannel. The test section consists of a bottom silicon substrate bonded with a top glass cover. Three consecutive parts of an inlet fluid plenum, a central microchannel and an outlet fluid plenum were etched in the silicon substrate. The central microchannel had a width of 800 mu m and a depth of 30 mu m. Acetone liquid was used as the working fluid. High outlet vapor qualities were dealt with here. The flow pattern consists of a fluid triangle (shrinkage of the liquid films) and a connected long liquid rivulet, which is generated in the central microchannel in the timescale of milliseconds. The peculiar flow pattern is formed due to the following reasons: (1) the liquid rivulet tends to have a large contact area with the top hydrophilic channel surface of the glass cover, but a smaller contact area with the bottom silicon hydrophobic surface. (2) The temperature gradient in the chip width direction at the top channel surface of the glass cover not only causes the shrinkage of the liquid films in the central microchannel upstream, but also attracts the liquid rivulet populated near the microchannel centerline. (3) The zigzag pattern is formed due to the competition between the evaporation momentum forces at the vapor-liquid interfaces and the force due to the Marangoni effect. The former causes the rivulet to deviate from the channel centerline and the latter draws the rivulet toward the channel centerline. (4) The temperature gradient along the flow direction in the central microchannel downstream causes the breakup of the rivulet to form isolated droplets there. (5) Liquid stripes inside the upstream fluid triangle were caused by the small capillary number of the liquid film, at which the large surface tension force relative to the viscous force tends to populate the liquid film locally on the top glass cover surface. |
| Keyword | Heat Sinks Instabilities Condensation |
| WOS Headings | Science & Technology ; Technology |
| DOI | 10.1088/0960-1317/19/5/055012 |
| WOS Subject Extended | Engineering ; Science & Technology - Other Topics ; Instruments & Instrumentation ; Materials Science ; Mechanics |
| WOS Keyword | HEAT SINKS ; INSTABILITIES ; CONDENSATION |
| Indexed By | SCI |
| Language | 英语 |
| Funding Organization | National Natural Science Foundation of China [50825603]; Natural Science Foundation of China [50776089] |
| WOS Subject | Engineering, Electrical & Electronic ; Nanoscience & Nanotechnology ; Instruments & Instrumentation ; Materials Science, Multidisciplinary ; Mechanics |
| WOS ID | WOS:000265580900022 |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://ir.giec.ac.cn/handle/344007/3288 |
| Collection | 中国科学院广州能源研究所 |
| Affiliation | 1.Chinese Acad Sci, Guangzhou Inst Energy Convers, Micro Energy Syst Lab, Guangzhou 510640, Peoples R China 2.N China Elect Power Univ, Beijing Key Lab Energy Safety & Clean Utilizat, Beijing 102206, Peoples R China |
| Recommended Citation GB/T 7714 | Zhang, Wei,Liu, Guohua,Xu, Jinliang,et al. Effect of channel surface wettability and temperature gradients on the boiling flow pattern in a single microchannel[J]. JOURNAL OF MICROMECHANICS AND MICROENGINEERING,2009,19(5):055012. |
| APA | Zhang, Wei,Liu, Guohua,Xu, Jinliang,&Yang, Yongping.(2009).Effect of channel surface wettability and temperature gradients on the boiling flow pattern in a single microchannel.JOURNAL OF MICROMECHANICS AND MICROENGINEERING,19(5),055012. |
| MLA | Zhang, Wei,et al."Effect of channel surface wettability and temperature gradients on the boiling flow pattern in a single microchannel".JOURNAL OF MICROMECHANICS AND MICROENGINEERING 19.5(2009):055012. |
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