Two-phase flow visualization and heat transfer performance of convective boiling in micro heat exchangers

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題名:	Two-phase flow visualization and heat transfer performance of convective boiling in micro heat exchangers
作者:	楊建裕;Liu, Wei-Chi;Yang, Chien-Yuh
貢獻者:	工學院機械工程學系
關鍵詞:	Applied sciences;Boiling;Chevron flow passage;Cooling;Corners;Design. Technologies. Operation analysis. Testing;Electronics;Evaporative cooling;Exact sciences and technology;Flow boiling;Flow visualization;Heat exchangers;Heat transfer;Heating;Integrated circuits;Micro heat exchanger;Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices;Thermal management
日期:	2014-01-01
上傳時間:	2026-04-23 15:32:00 (UTC+8)
出版者:	Elsevier Inc.;Amsterdam: Elsevier Inc
摘要:	摘要： •Flow boiling heat transfer coefficient (HTC) in a micro heat exchanger (HX) with straight and chevron flow passages were tested.•The boiling flow pattern was also observed for further understanding of the heat transfer mechanisms.•The HTC increased with increasing heat flux in the chevron passages HX but decreased in the straight passages HX.•The partial dryout area ratio and time fraction increased with increasing heat flux for the straight passages.•No partial dryout was observed for flow boiling in chevron passages heat exchanger. Attributed to its high heat transfer coefficient, evaporating cooling involving the use of micro heat exchangers is considered a possible thermal management solution for cooling of high heat flux electronic devices. The desire to develop high-performance micro heat exchangers operating in the evaporation regime provides a major motivation for the present work. Flow boiling heat transfer in a micro heat exchanger with straight and chevron flow passages were tested in the present study. The boiling flow pattern was also observed for further understanding of the heat transfer mechanisms. The test results show that the heat transfer coefficient increased with increasing flow rate in both chevron and straight flow passages micro heat exchangers. But the effect of heat flux on the heat transfer coefficient in the straight passages heat exchanger is in adverse to that in the chevron passages heat exchanger. The heat transfer coefficient increased with increasing heat flux in the chevron passages heat exchanger but decreased in the straight passages heat exchanger. The flow visualization through transparent cover heat exchangers shows that partial dryout happened in the straight passages heat exchanger at the lowest heating rate condition. This caused a poor heat transfer area and significantly degraded the overall heat transfer performance. The partial dryout area ratio and time fraction increased with increasing heat flux and therefore the heat transfer coefficients decreased with increasing heating rate. For flow boiling in chevron passages heat exchanger, liquid film was dragged at the intersection corner between the upper and lower plate chevron passages by the surface tension force and supplement liquid flowed back into the heating surface from other chevron passages. No partial dryout was observed and therefore, the heat transfer performance test results followed the trend of conventional correlations. 出版者： Amsterdam: Elsevier Inc 出版日期： 2014-09-01 出處： Experimental thermal and fluid science, 2014-09, Vol.57, p.358-364 版權： 2014 Elsevier Inc. 版權： 2015 INIST-CNRS 識別號： ISSN: 0894-1777 識別號： EISSN: 1879-2286 識別號： DOI: 10.1016/j.expthermflusci.2014.06.002
顯示於類別:	[機械工程學系] 期刊論文

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