In this experimental work, heat transfer and thermal performance factor of double-pipe heat exchanger pipes with rotated inclined elliptical (RIE) inserts are examined. The rotation angle of the elliptical turbulators $\left(\beta \right)$, slant angle $\left(\alpha \right)$, and the perforation diameters (d_p) were in the range of $0^{\circ }\le \beta \le {90}^{\circ }$, ${15}^{\circ }\le \alpha \le {25}^{\circ }$, and $0.5mm\le d_p\le 1.5mm$, respectively. The rotated inserts with perforations can substantially intensify the flow unsteadiness and disturb the thermal boundary layer to improve the thermal performance without a perceptible effect on the pressure drop. The experimental analysis showed that the heat transfer is improved up to 30.7% by utilizing RIE turbulators in comparison with the non-rotated elliptic (NRIE) turbulators. The recirculating flows across the perforations of the elliptical inserts rise the fluid mixing amongst the tube wall and the central region. The highest thermal performance factor of 2.23 is achieved for RIE turbulators with $\beta ={90}^{\circ }$, d_p/b=0.250 and $\alpha ={25}^{\circ }$. The thermal performance factor that is obtained in this study is noticeably higher than that of the previous studies, without increasing the manufacturing costs. The heat transfer coefficient is enhanced by 59.95% by utilizing NRIE vortex generators with d_p=1.5 mm in comparison with the typical non-rotated louvered strips without perforations.

在这项实验工作中，研究了带有旋转倾斜椭圆 (RIE) 插入件的双管换热器管道的传热和热性能因素。椭圆湍流器的旋转角度$\left(\beta \right)$, 倾斜角度 $\left(\alpha \right)$和穿孔的直径（d _p）是在范围内$0^{\circ }\le \beta \le {90}^{\circ }$, ${15}^{\circ }\le \alpha \le {25}^{\circ }$， 和 $0.5米米\le d_{磷}\le 1.5米米$， 分别。带有穿孔的旋转插入件可以显着增强流动的不稳定性并扰乱热边界层以提高热性能，而对压降没有明显影响。实验分析表明，与非旋转椭圆 (NRIE) 湍流器相比，使用 RIE 湍流器的传热提高了 30.7%。穿过椭圆形插入件穿孔的再循环流使管壁和中心区域之间的流体混合上升。RIE 湍流器的最高热性能系数为 2.23$\beta ={90}^{\circ }$，d _p / B = 0.250和$\alpha ={25}^{\circ }$. 本研究中获得的热性能系数明显高于之前的研究，而不会增加制造成本。与没有穿孔的典型非旋转百叶窗条相比，通过使用d _p = 1.5 mm 的NRIE 涡流发生器，传热系数提高了 59.95% 。