ABSTRACT The influence of serrated circular rings with rectangular winglets (SCRWRW) on the thermal performance of circular tube heat exchanger has been studied experimentally and computationally. The geometrical parameters considered are diameter ratio (DR = 0.8, 0.85), pitch ratio (PR = 3, 4), attack angle (ϴ = 15°, 30°, 45°), and blockage ratio (0.05). The test section is a circular tube of length 1.5 m and diameter 68.1 mm, in which uniform heat flux of 1000 W/m2 has been applied. Air is the working fluid flowing in the range of Reynolds number between 6000 and 24000. The results obtained showed that SCRWRW enhances heat transfer rate 5.54 times of smooth tube while the maximum thermal performance obtained is 3.2 at DR = 0.85, PR = 3, and ϴ = 15°. The computational investigation has also been carried out using Ansys fluent and presented the effect of SCRWRW on temperature distribution and fluid flow. Abbreviations SCR: Serrated Circular Ring; SCRWRW: Serrated Circular Ring with Rectangular Winglets; DR: Diameter Ratio (d/D); PR: Pitch Ratio (l/D); BR: Blockage Ratio (H/D)

中文翻译：

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矩形小翼锯齿圆环对管式换热器热性能的影响：实验与数值研究

摘要 矩形小翼锯齿圆环 (SCRWRW) 对圆管换热器热性能的影响进行了实验和计算研究。考虑的几何参数是直径比 (DR = 0.8, 0.85)、螺距比 (PR = 3, 4)、攻角 (ϴ = 15°、30°、45°) 和堵塞比 (0.05)。试验段是一根长1.5 m、直径68.1 mm的圆管，其中施加了1000 W/m2的均匀热通量。空气是雷诺数在 6000 到 24000 范围内流动的工质。 结果表明，SCRWRW 提高了光滑管的传热率 5.54 倍，而在 DR = 0.85，PR = 3 时获得的最大热性能为 3.2，并且ϴ = 15°。还使用 Ansys fluent 进行了计算研究，并展示了 SCRWRW 对温度分布和流体流动的影响。缩写 SCR：锯齿圆环；SCRWRW：带矩形小翼的锯齿圆环；DR：直径比（d/D）；PR：螺距比 (l/D)；BR：阻塞率（H/D）