Single bubble geometry evolution in micro-scale space

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• 作者：Yuan Wang^a ; ^{ywangedi@gmail.com} ; Khellil Sefiane^b
• 关键词：Bubble growth ; Superheating ; High aspect ratio micro-channel ; Flow boiling ; Transparent heating
• 刊名：International Journal of Thermal Sciences
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：67
• 期：Complete
• 页码：31-40
• 全文大小：1386 K

文摘

Two types of single vapour bubble growth in micro-scale space are experimentally investigated. Degassed pentane and FC-72 are used to study the bubble confined between superheated parallel plates without liquid flow. Liquid properties which are influential on bubble growth are discussed. Effects of plate superheating and plate gap on bubble growth rate are examined. Bubble growth during flow boiling in high aspect ratio micro-channels is also examined to extensively investigate the single bubble growth in a dynamic configuration. The hydraulic diameters of the tested channel are 571?¦Ìm, 762?¦Ìm and 1454?¦Ìm, with an aspect ratio of 20, 20 and 10 respectively. Transparent heating technique is utilised to provide heating power while ensuring sufficient transparency for visualisation. A three-stage bubble growth mode is presented. Moreover, bubble geometry evolution is found to be strongly related to channel cross-sectional geometry but slightly affected by heat flux or mass flux. Bubble growth critical time is defined. Bubble equivalent radius, bubble aspect ratio and width versus length trends are also discussed.