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首页> 外文期刊>International Journal of Heat and Mass Transfer >Saturated Flow Boiling Heat Transfer Of R-407c And Associated Bubble Characteristics In A Narrow Annular Duct
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Saturated Flow Boiling Heat Transfer Of R-407c And Associated Bubble Characteristics In A Narrow Annular Duct

机译：R-407c的饱和流动沸腾传热和窄环形管中的气泡特性

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摘要

Experiments are conducted here to investigate how the channel size affects the R-407C saturated flow boiling heat transfer and associated bubble characteristics in a horizontal narrow annular duct. The gap of the duct is fixed at 1.0 and 2.0 mm in this study. The measured data indicate that the saturated flow boiling heat transfer coefficient increases with a decrease in the duct gap. Besides, raising the imposed heat flux can cause a significant increase in the boiling heat transfer coefficients. However, the effects of the refrigerant mass flux and saturated temperature on the boiling heat transfer coefficient are milder. The results from the flow visualization show that the mean diameter of the bubbles departing from the heating surface decreases noticeably at increasing R-407C mass flux. Moreover, the bubble departure frequency increases at reducing duct size and at a high imposed heat flux many bubbles generated from the cavities in the heating surface tend to merge together to form big bubbles. Meanwhile comparison of the present heat transfer data for R-407C with R-134a in the same duct and with some existing correlations is conducted. Furthermore, correlation for the present R-407C saturated flow boiling heat transfer data is proposed. Additionally, the present data for some quantitative bubble characteristics such as the mean bubble departure diameter and frequency and the active nucleation site density are also correlated.
机译：在此进行实验，以研究通道尺寸如何影响水平窄环形管道中R-407C饱和流沸腾传热以及相关的气泡特性。在这项研究中，导管的间隙固定为1.0和2.0 mm。实测数据表明，饱和流沸腾换热系数随管道间隙的减小而增大。此外，提高施加的热通量会引起沸腾传热系数的显着增加。但是，制冷剂质量通量和饱和温度对沸腾传热系数的影响较小。流动可视化的结果表明，离开加热表面的气泡的平均直径随着R-407C质量流量的增加而明显减小。此外，气泡离开频率随着减小的管道尺寸而增加，并且在高的施加的热通量下，从加热表面中的腔产生的许多气泡趋于合并在一起以形成大的气泡。同时，将R-407C与R-134a在同一导管中的当前传热数据进行了比较，并进行了一些相关的比较。此外，提出了与当前R-407C饱和流沸腾传热数据的相关性。此外，一些定量气泡特征（例如平均气泡离开直径和频率以及活性成核位点密度）的当前数据也相互关联。

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