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Experimental investigation of hydrothermal characteristics for flow within a circular tube equipped with twisted conical strip inserts under different alignments
Journal of the Taiwan Institute of Chemical Engineers ( IF 5.7 ) Pub Date : 2020-09-29 , DOI: 10.1016/j.jtice.2020.09.002
Mehdi Bahiraei , Khashayar Gharagozloo

This study attempts to experimentally investigate the thermohydraulic characteristics inside a tube fitted with the staggered and non-staggered twisted conical strip inserts. The inserts are built via stereolithography 3D printer. The influences of geometrical attributes such as alignment type (i.e., staggered or non-staggered) and the pitch ratio as well as the Reynolds number (Re) on the Nusselt number (Nu) and friction factor (f) are examined. Because of flow mixing and vortex creation in the flow path, the tube fitted with the conical inserts has greater Nu and f in comparison with the smooth tube. The Nu and f have larger amounts in the tube having the non-staggered inserts in comparison with that with the staggered ones. With the pitch ratio elevation, the Nu and f diminish, while the elevation in the Re decreases the f and enhances the Nu. Thus, the highest Nusselt number and pressure drop belong to the non-staggered insert with pitch ratio of 2.5 and Reynolds number of 2250 with amounts of 15.15 and 795 Pa, respectively. The highest improvement of the Nusselt number in comparison with the plain tube occurs at Reynolds number of 350 for the non-staggered insert with pitch ratio of 2.5, which is recorded about 133.8%. Besides, the performance evaluation criterion (PEC) is higher than 1 at Re numbers of 820 and less than 820, which shows the proper merit of applying both the staggered and non-staggered inserts in this Re span. For small Re, the non-staggered inserts lead to larger PEC than the staggered ones, while an opposite outcome is observed for the high Reynolds numbers. The highest PEC is about 1.56, which belongs to the non-staggered alignment with pitch ratio of 5 and Reynolds number of 350.



中文翻译:

带有不同排列方向的扭曲锥形带状插入件的圆管内流动的水热特性的实验研究

本研究试图通过实验研究装有交错和非交错扭曲锥形条形插入件的管子内部的热工液压特性。插件是通过立体光刻3D打印机构建的。检验了诸如对准类型(即交错或非交错)和节距比以及雷诺数(Re)等几何属性对Nusselt数(Nu)和摩擦系数(f)的影响。由于在流动路径中发生混流和产生涡流,因此,与光滑管相比,装有锥形插件的管的Nu和f更大。Nu和f与具有交错的插入件的管相比,具有非交错的插入件的管中的金属的量更大。随着螺距比的升高,Nu和f减小,而Re中的升高会减小f并增强Nu。因此,最高的努塞尔数和压降属于节距比为2.5的非交错刀片,雷诺数为2250,数量分别为15.15和795 Pa。相对于普通管,努塞尔数的最大改进出现在螺距比为2.5的无交错刀片的雷诺数为350的情况下,据记录约为133.8%。此外,Re的性能评估标准(PEC)高于1数目小于820且小于820,这表明在此Re span中同时应用交错和非交错插入的适当优点。对于较小的Re,未交错的插入物会导致PEC大于交错的插入物,而对于高雷诺数,则观察到相反的结果。最高PEC约为1.56,属于无交错排列,节距比为5,雷诺数为350。

更新日期:2020-10-16
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