Jiajia Song , Hequn Liu , Chao Yuan , Ran Wang , Jinqing Peng , Lizhi Wang , Haobo Jiang , Houpei Li
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The local vapor quality in the header was solved for using a correlation derived from the pre-experiments. The distribution of local vapor quality showed that gases were concentrated upstream of the header, while liquids were concentrated in the middle and lower reaches. The local vapor quality reached a minimum and remained constant at 0.1 in the middle and lower reaches, unaffected by changes in inlet conditions. As the mass flux increased, both the local vapor quality maximum point and the minimum point in the header were shifted back toward the downstream. Additionally, the increase of mass flux caused the fluctuation of the standard deviation increased, which meant the stability of the flow decreased. The two-phase flow measurement technique based on flexible capacitance sensors proposed in this study realized the extension of the capacitive method from the experimental stage to the industrial application stage.</p></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Quantification of two-phase flow in a microchannel heat exchanger header based on capacitance measurement\",\"authors\":\"Jiajia Song , Hequn Liu , Chao Yuan , Ran Wang , Jinqing Peng , Lizhi Wang , Haobo Jiang , Houpei Li\",\"doi\":\"10.1016/j.ijrefrig.2024.06.003\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The two-phase distribution has always been one of the research focuses of microchannel heat exchangers, because the maldistribution could seriously affect the heat transfer performance. 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As the mass flux increased, both the local vapor quality maximum point and the minimum point in the header were shifted back toward the downstream. Additionally, the increase of mass flux caused the fluctuation of the standard deviation increased, which meant the stability of the flow decreased. 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引用次数: 0
摘要
两相分布一直是微通道换热器的研究重点之一,因为两相分布不均会严重影响换热性能。本文开发了一种电容方法,用于量化微通道热交换器铝制集管中汽液两相流的分布。使用柔性电容传感器量化了 R134a 的两相分布。入口质量流量从 17.47 kg m-2 s-1 到 52.42 kg m-2 s-1 不等,入口蒸汽质量从 0.2 到 0.6 不等。归一化的时间平均电容信号经过高斯函数处理,得到数学期望值和标准偏差。利用预实验得出的相关性求解了顶管中的局部蒸汽质量。局部蒸汽质量的分布表明,气体集中在集管上游,而液体则集中在中下游。中下游的局部蒸汽质量达到最小值并保持在 0.1,不受入口条件变化的影响。随着质量通量的增加,本地蒸汽质量最大点和集流管中的最小点都向下游后移。此外,质量通量的增加导致标准偏差的波动增大,这意味着流量的稳定性下降。本研究提出的基于柔性电容传感器的两相流量测量技术实现了电容法从实验阶段向工业应用阶段的延伸。
Quantification of two-phase flow in a microchannel heat exchanger header based on capacitance measurement
The two-phase distribution has always been one of the research focuses of microchannel heat exchangers, because the maldistribution could seriously affect the heat transfer performance. This paper developed a capacitive method to quantify the two-phase distribution of vapor-liquid flow in the aluminum header of a microchannel heat exchanger. A flexible capacitance sensor was used to quantify the two-phase distribution with R134a. The inlet mass fluxes vary from 17.47 kg m−2 s−1 to 52.42 kg m−2 s−1 and inlet vapor qualities range from 0.2 to 0.6. The normalized time-averaged capacitance signal was processed by a Gaussian function to obtain the mathematical expectation and the standard deviation. The local vapor quality in the header was solved for using a correlation derived from the pre-experiments. The distribution of local vapor quality showed that gases were concentrated upstream of the header, while liquids were concentrated in the middle and lower reaches. The local vapor quality reached a minimum and remained constant at 0.1 in the middle and lower reaches, unaffected by changes in inlet conditions. As the mass flux increased, both the local vapor quality maximum point and the minimum point in the header were shifted back toward the downstream. Additionally, the increase of mass flux caused the fluctuation of the standard deviation increased, which meant the stability of the flow decreased. The two-phase flow measurement technique based on flexible capacitance sensors proposed in this study realized the extension of the capacitive method from the experimental stage to the industrial application stage.
期刊介绍:
The International Journal of Refrigeration is published for the International Institute of Refrigeration (IIR) by Elsevier. It is essential reading for all those wishing to keep abreast of research and industrial news in refrigeration, air conditioning and associated fields. This is particularly important in these times of rapid introduction of alternative refrigerants and the emergence of new technology. The journal has published special issues on alternative refrigerants and novel topics in the field of boiling, condensation, heat pumps, food refrigeration, carbon dioxide, ammonia, hydrocarbons, magnetic refrigeration at room temperature, sorptive cooling, phase change materials and slurries, ejector technology, compressors, and solar cooling.
As well as original research papers the International Journal of Refrigeration also includes review articles, papers presented at IIR conferences, short reports and letters describing preliminary results and experimental details, and letters to the Editor on recent areas of discussion and controversy. Other features include forthcoming events, conference reports and book reviews.
Papers are published in either English or French with the IIR news section in both languages.