The collapse behavior of vapor bubbles containing non-condensable gas by direct contact condensation
Direct contact condensation (DCC) is a phenomenon that occurs when vapor is injected into a subcooled water pool and is essential in many industrial devices. However, the actual phenomenon involves non-condensable gases in the vapor, and there has been insufficient research on how non-condensable ga...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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The Japan Society of Mechanical Engineers
2024-01-01
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| Series: | Mechanical Engineering Journal |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/mej/11/2/11_23-00482/_pdf/-char/en |
| _version_ | 1797206042096959488 |
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| author | Motohiro NAKAHATA Noor SAFFREENA Akiko KANEKO |
| author_facet | Motohiro NAKAHATA Noor SAFFREENA Akiko KANEKO |
| author_sort | Motohiro NAKAHATA |
| collection | DOAJ |
| description | Direct contact condensation (DCC) is a phenomenon that occurs when vapor is injected into a subcooled water pool and is essential in many industrial devices. However, the actual phenomenon involves non-condensable gases in the vapor, and there has been insufficient research on how non-condensable gases affect direct contact condensation. In this study, through the detailed observation of the bubble collapse behavior using a high-speed video camera, we aimed to clarify the bubble collapse behavior and heat transfer coefficient of vapor bubbles containing non-condensable gas by DCC. Experiments were compared between DCC under pure vapor conditions and DCC under conditions containing non-condensable gas. Characteristic quantities for each condition were calculated from image analysis of the captured images. The temperature distribution inside the plume was also measured using thermocouples. From these data, the relationship between contraction rate and microbubbles diameter and the average heat transfer coefficient (HTC) were estimated. As a result, the construction rate of the plume containing non-condensable gas was reduced to 4 ~ 20 % of that of pure vapor, and large number of microbubbles were observed under lower air mass fraction with the log-normal distribution in diameter. The average HTC decreased to about 5 ~ 13 % when the non-condensable gas was mixed with about 8 % of air mass fraction. These results were proposed to be because vapor concentration decreases as the plume shrinks and vapor diffusion is suppressed by the mass conservation of non-condensable gas as the vapor condenses. |
| first_indexed | 2024-04-24T09:00:43Z |
| format | Article |
| id | doaj.art-61b4e06bea724d40a862ed614cf03ce4 |
| institution | Directory Open Access Journal |
| issn | 2187-9745 |
| language | English |
| last_indexed | 2024-04-24T09:00:43Z |
| publishDate | 2024-01-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Mechanical Engineering Journal |
| spelling | doaj.art-61b4e06bea724d40a862ed614cf03ce42024-04-16T01:29:36ZengThe Japan Society of Mechanical EngineersMechanical Engineering Journal2187-97452024-01-0111223-0048223-0048210.1299/mej.23-00482mejThe collapse behavior of vapor bubbles containing non-condensable gas by direct contact condensationMotohiro NAKAHATA0Noor SAFFREENA1Akiko KANEKO2Degree program in Systems and Information Engineering, University of TsukubaDegree program in Systems and Information Engineering, University of TsukubaInstitute of Systems and Information Engineering, University of TsukubaDirect contact condensation (DCC) is a phenomenon that occurs when vapor is injected into a subcooled water pool and is essential in many industrial devices. However, the actual phenomenon involves non-condensable gases in the vapor, and there has been insufficient research on how non-condensable gases affect direct contact condensation. In this study, through the detailed observation of the bubble collapse behavior using a high-speed video camera, we aimed to clarify the bubble collapse behavior and heat transfer coefficient of vapor bubbles containing non-condensable gas by DCC. Experiments were compared between DCC under pure vapor conditions and DCC under conditions containing non-condensable gas. Characteristic quantities for each condition were calculated from image analysis of the captured images. The temperature distribution inside the plume was also measured using thermocouples. From these data, the relationship between contraction rate and microbubbles diameter and the average heat transfer coefficient (HTC) were estimated. As a result, the construction rate of the plume containing non-condensable gas was reduced to 4 ~ 20 % of that of pure vapor, and large number of microbubbles were observed under lower air mass fraction with the log-normal distribution in diameter. The average HTC decreased to about 5 ~ 13 % when the non-condensable gas was mixed with about 8 % of air mass fraction. These results were proposed to be because vapor concentration decreases as the plume shrinks and vapor diffusion is suppressed by the mass conservation of non-condensable gas as the vapor condenses.https://www.jstage.jst.go.jp/article/mej/11/2/11_23-00482/_pdf/-char/endirect contact condensationplume collapsevisualization measurementnon condensation gasaverage heat coefficientmicrobubbles |
| spellingShingle | Motohiro NAKAHATA Noor SAFFREENA Akiko KANEKO The collapse behavior of vapor bubbles containing non-condensable gas by direct contact condensation Mechanical Engineering Journal direct contact condensation plume collapse visualization measurement non condensation gas average heat coefficient microbubbles |
| title | The collapse behavior of vapor bubbles containing non-condensable gas by direct contact condensation |
| title_full | The collapse behavior of vapor bubbles containing non-condensable gas by direct contact condensation |
| title_fullStr | The collapse behavior of vapor bubbles containing non-condensable gas by direct contact condensation |
| title_full_unstemmed | The collapse behavior of vapor bubbles containing non-condensable gas by direct contact condensation |
| title_short | The collapse behavior of vapor bubbles containing non-condensable gas by direct contact condensation |
| title_sort | collapse behavior of vapor bubbles containing non condensable gas by direct contact condensation |
| topic | direct contact condensation plume collapse visualization measurement non condensation gas average heat coefficient microbubbles |
| url | https://www.jstage.jst.go.jp/article/mej/11/2/11_23-00482/_pdf/-char/en |
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