Condensation heat transfer in smooth and three-dimensional dimpled tubes of various materials

IF 1.5 4区 工程技术 Q3 ENGINEERING, MECHANICAL
Wei Li
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Abstract

The heat transfer and pressure drop of R410A and R32 within a smooth and an enhanced dimpled tube were measured for mass fluxes from 100 kg m−2 s−1 to 400 kg m−2 s−1, average vapor qualities between 0.2 and 0.8, and saturation temperatures between 35℃ and 45℃.dimpled. The test section length was 2 meters, and the outer and inner diameters of the tubes were 9.52 and 8.32 mm, respectively. The inner surface of the enhanced tube was dimpled. Three dimpled tubes and three smooth tubes, differing by material (copper, aluminum, and stainless steel) were tested to examine the material effect. The measured condensation heat transfer coefficient (HTC) for the copper smooth tube was between 1.10 to 1.16 times higher than that of the aluminum, and likewise, between 1.19 to 1.31 times higher than that of the stainless-steel tube. Similarly, the condensation HTC for the copper dimpled tube was between 1.06 to 1.15 times higher than that of the aluminum dimpled tube, and between 1.26 to 1.38 times higher than that of stainless-steel tube dimpled tube. In general, and the condensation HTC for R32 was greater than that for R410A owed mainly to the greater liquid thermal conductivity of R32. Flow patterns were observed for different vapor qualities and use to establish corresponding heat transfer mechanisms. Finally, a new correlation for dimpled tubes was proposed based a modified smooth tube correlation, which predicted the measurements to within 20 %.
各种材料的光滑管和三维凹陷管中的冷凝传热
在质量流量为 100 kg m-2 s-1 至 400 kg m-2 s-1、平均蒸汽品质为 0.2 至 0.8、饱和温度为 35℃ 至 45℃ 的情况下,测量了 R410A 和 R32 在光滑管和增强凹陷管内的传热和压降。试验段长度为 2 米,管子的外径和内径分别为 9.52 毫米和 8.32 毫米。增强管的内表面是凹陷的。测试了三根凹陷管和三根光滑管,材料不同(铜、铝和不锈钢),以检验材料的影响。测得的铜光滑管冷凝传热系数(HTC)比铝管高 1.10 至 1.16 倍,同样,比不锈钢管高 1.19 至 1.31 倍。同样,铜凹陷管的冷凝 HTC 是铝凹陷管的 1.06 至 1.15 倍,是不锈钢凹陷管的 1.26 至 1.38 倍。一般来说,R32 的冷凝 HTC 要高于 R410A,这主要是因为 R32 的液体导热性更高。我们观察了不同蒸汽质量的流动模式,并利用这些模式建立了相应的传热机制。最后,根据修改后的光滑管相关性,为凹陷管提出了一种新的相关性,该相关性对测量结果的预测在 20% 以内。
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来源期刊
Journal of Enhanced Heat Transfer
Journal of Enhanced Heat Transfer 工程技术-工程:机械
CiteScore
3.60
自引率
8.70%
发文量
51
审稿时长
12 months
期刊介绍: The Journal of Enhanced Heat Transfer will consider a wide range of scholarly papers related to the subject of "enhanced heat and mass transfer" in natural and forced convection of liquids and gases, boiling, condensation, radiative heat transfer. Areas of interest include: ■Specially configured surface geometries, electric or magnetic fields, and fluid additives - all aimed at enhancing heat transfer rates. Papers may include theoretical modeling, experimental techniques, experimental data, and/or application of enhanced heat transfer technology. ■The general topic of "high performance" heat transfer concepts or systems is also encouraged.
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