Knowledge Management System Of Guangzhou Institute of Energy Conversion, CAS
| Seed bubbles stabilize flow and heat transfer in parallel microchannels | |
| Xu, Jinliang; Liu, Guohua; Zhang, Wei; Li, Qian; Wang, Bin | |
| 2009-08-01 | |
| Source Publication | INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
 |
| ISSN | 0301-9322 |
| Volume | 35Issue:8Pages:773-790 |
| Corresponding Author | xujl@ms.giec.ac.cn |
| Abstract | Seed bubbles are generated on microheaters located at the microchannel upstream and driven by a pulse voltage signal, to improve flow and heat transfer performance in microchannels. The present study investigates how seed bubbles stabilize flow and heat transfer in micro-boiling systems. For the forced convection flow, when heat flux at the wall surface is continuously increased, flow instability is self-sustained in microchannels with large oscillation amplitudes and long periods. Introduction of seed bubbles in time sequence improves flow and heat transfer performance significantly. Low frequency (similar to 10 Hz) seed bubbles not only decrease oscillation amplitudes of pressure drops, fluid inlet and outlet temperatures and heating surface temperatures, but also shorten oscillation cycle periods. High frequency (similar to 100 Hz or high) seed bubbles completely suppress the flow instability and the heat transfer system displays stable parameters of pressure drops, fluid inlet and outlet temperatures and heating surface temperatures. Flow visualizations show that a quasi-stable boundary interface from spheric bubble to elongated bubble is maintained in a very narrow distance range at any time. The seed bubble technique almost does not increase the pressure drop across microsystems, which is thoroughly different from those reported in the literature. The higher the seed bubble frequency, the more decreased heating surface temperatures are. A saturation seed bubble frequency of 1000-2000 Hz can be reached, at which heat transfer enhancement attains the maximum degree, inferring a complete thermal equilibrium of vapor and liquid phases in microchannels. Benefits of the seed bubble technique are the stabilization of flow and heat transfer, decreasing heating surface temperatures and improving temperature uniformity of the heating surface. (C) 2009 Elsevier Ltd. All rights reserved. |
| Subtype | Article |
| Other Abstract | Seed bubbles are generated on microheaters located at the microchannel upstream and driven by a pulse voltage signal, to improve flow and heat transfer performance in microchannels. The present study investigates how seed bubbles stabilize flow and heat transfer in micro-boiling systems. For the forced convection flow, when heat flux at the wall surface is continuously increased, flow instability is self-sustained in microchannels with large oscillation amplitudes and long periods. Introduction of seed bubbles in time sequence improves flow and heat transfer performance significantly. Low frequency (similar to 10 Hz) seed bubbles not only decrease oscillation amplitudes of pressure drops, fluid inlet and outlet temperatures and heating surface temperatures, but also shorten oscillation cycle periods. High frequency (similar to 100 Hz or high) seed bubbles completely suppress the flow instability and the heat transfer system displays stable parameters of pressure drops, fluid inlet and outlet temperatures and heating surface temperatures. Flow visualizations show that a quasi-stable boundary interface from spheric bubble to elongated bubble is maintained in a very narrow distance range at any time. The seed bubble technique almost does not increase the pressure drop across microsystems, which is thoroughly different from those reported in the literature. The higher the seed bubble frequency, the more decreased heating surface temperatures are. A saturation seed bubble frequency of 1000-2000 Hz can be reached, at which heat transfer enhancement attains the maximum degree, inferring a complete thermal equilibrium of vapor and liquid phases in microchannels. Benefits of the seed bubble technique are the stabilization of flow and heat transfer, decreasing heating surface temperatures and improving temperature uniformity of the heating surface. |
| Keyword | Seed Bubble Microchannel Boiling Flow Instability Saturation Seed Bubble Frequency |
| WOS Headings | Science & Technology ; Technology |
| DOI | 10.1016/j.ijmultiphaseflow.2009.03.008 |
| WOS Subject Extended | Mechanics |
| URL | 查看原文 |
| WOS Keyword | BOILING INSTABILITY ; SINKS ; FLUXES |
| Indexed By | SCI |
| Language | 英语 |
| Funding Organization | National Natural Science Foundation of China [50825603] |
| WOS Subject | Mechanics |
| WOS ID | WOS:000268403500007 |
| Citation statistics | |
| Document Type | 期刊论文 |
| Identifier | http://ir.giec.ac.cn/handle/344007/3308 |
| Collection | 中国科学院广州能源研究所 |
| Affiliation | Chinese Acad Sci, Guangzhou Inst Energy Convers, Micro Energy Syst Lab, Guangzhou 510640, Guangdong, Peoples R China |
| Recommended Citation GB/T 7714 | Xu, Jinliang,Liu, Guohua,Zhang, Wei,et al. Seed bubbles stabilize flow and heat transfer in parallel microchannels[J]. INTERNATIONAL JOURNAL OF MULTIPHASE FLOW,2009,35(8):773-790. |
| APA | Xu, Jinliang,Liu, Guohua,Zhang, Wei,Li, Qian,&Wang, Bin.(2009).Seed bubbles stabilize flow and heat transfer in parallel microchannels.INTERNATIONAL JOURNAL OF MULTIPHASE FLOW,35(8),773-790. |
| MLA | Xu, Jinliang,et al."Seed bubbles stabilize flow and heat transfer in parallel microchannels".INTERNATIONAL JOURNAL OF MULTIPHASE FLOW 35.8(2009):773-790. |
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