Abstract In order to increase the performance of a heat exchanger flowing ethylene glycol (EG) and water (W) mixtures, the effects of different twisted tapes on heat transfer and flow characteristics in a heat exchanger tube is experimentally investigated. Material of the twisted tapes and the tube is selected as stainless steel. Three different volumetric ratios of EG and W mixtures are used with the volumetric ratio of (0:100), (20:80) and (40:60). The twisted tapes having twist ratio of 5.88 are perforated and dimpled with pitch ratio of (Pp/y and Pd/y) of 0.25, 0.5 and 1.0. The experiments are conducted under constant heat flux and Reynold number ranging from 5217 to 22,754. The experiments for both the smooth tube and the typical twisted tape inserted tube are validated with the literature. The results indicated that the use of twisted tape inserts enhances the heat transfer performance. Experimental results revealed that novelty dimpled twisted tape insert provides higher heat transfer performance than the others. Adding the ethylene glycol on pure water has not major role on increase in the friction factor. As the amount of ethylene glycol in the mixture increases, thermo hydraulic performance decreases. The best thermo-hydraulic performance results are obtained as 1.42, 1.17 and 1.05 for dimpled twisted tape (Pd/y = 0.25) inserted tube at the lowest Reynolds numbers for the fluids which are (0:100), (20:80) and (40:60), respectively.

中文翻译：

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带平面、穿孔和凹坑扭曲带插入件的管增强传热和流动特性的实验研究

摘要 为了提高乙二醇（EG）和水（W）混合物流动的换热器的性能，实验研究了不同绞合带对换热器管内传热和流动特性的影响。扭带和管材选用不锈钢。使用三种不同体积比的 EG 和 W 混合物，体积比为 (0:100)、(20:80) 和 (40:60)。扭曲比为5.88的扭曲带以0.25、0.5和1.0的节距比(Pp/y和Pd/y)穿孔和凹坑。实验在恒定热通量和雷诺数范围从 5217 到 22,754 下进行。光滑管和典型的扭带插入管的实验都用文献进行了验证。结果表明，使用扭绞带插入物提高了传热性能。实验结果表明，新颖的波纹扭曲带插入物比其他插入物提供更高的传热性能。在纯水中加入乙二醇对摩擦系数的增加作用不大。随着混合物中乙二醇量的增加，热水力性能下降。在最低雷诺数为 (0:100)、(20:80) 和 (20:80) 的流体中，凹痕扭曲带 (Pd/y = 0.25) 插入管的最佳热液压性能结果为 1.42、1.17 和 1.05。 (40:60)，分别。在纯水中加入乙二醇对摩擦系数的增加作用不大。随着混合物中乙二醇量的增加，热水力性能下降。在最低雷诺数为 (0:100)、(20:80) 和 (20:80) 的流体中，凹痕扭曲带 (Pd/y = 0.25) 插入管的最佳热液压性能结果为 1.42、1.17 和 1.05。 (40:60)，分别。在纯水中加入乙二醇对摩擦系数的增加作用不大。随着混合物中乙二醇量的增加，热水力性能下降。在最低雷诺数为 (0:100)、(20:80) 和 (20:80) 的流体中，凹痕扭曲带 (Pd/y = 0.25) 插入管的最佳热液压性能结果为 1.42、1.17 和 1.05。 (40:60)，分别。