ABSTRACT

This paper experimentally and numerically studied the effects of inserting circular rings with four angular indexes and three diameter ratios at Re = 5000–24000 using air as the working fluid in a pipe. Researchers have proposed obstacles with various geometries to improve thermal performance in heat exchangers. However, research has not fully addressed the application of circular ring obstacles with different angle indexes and obstacle structure optimization. The results indicated, the Nusselt number increased by inserting a circular ring with an angular index of (360, 270, 180, and 90) by 3.9, 3.15, 2.92, and 2.74 times compared to a smooth tube, respectively. Likewise, the thermal performance coefficient for ring obstacles improves by 1.32, 1.39, 1.55, 1.8 times, respectively. Also, by increasing the ring diameter ratio, the Nusselt number increases, the friction coefficient decreases, and the thermal performance coefficient increases. Thus, it is be concluded that the better thermal performance of a circular ring’s cut sections as a passive component makes it a good choice for heat transfer and industrial applications. Besides, the results indicate that thermal efficiency in the case of using a ring with less angular index is higher, making it an appropriate choice economically.

摘要

本文通过实验和数值研究了在 Re = 5000–24000 时使用空气作为工作流体在管道中插入具有四个角指数和三个直径比的圆环的效果。研究人员提出了各种几何形状的障碍物，以提高热交换器的热性能。然而，研究尚未完全解决不同角度指标的圆环障碍物的应用和障碍物结构优化问题。结果表明，插入角指数为（360、270、180 和 90）的圆环与光滑管相比，努塞尔数分别增加了 3.9、3.15、2.92 和 2.74 倍。同样，环形障碍物的热性能系数分别提高了 1.32、1.39、1.55、1.8 倍。另外，通过增大环径比，努塞尔数增大，摩擦系数减小，热性能系数增大。因此，可以得出结论，圆环切割截面作为无源元件的更好的热性能使其成为传热和工业应用的良好选择。此外，结果表明，在使用角指数较小的环的情况下，热效率较高，使其成为经济上合适的选择。