Abstract

The insertion of a broken twisted tape (BTT) in tube is a novel passive heat transfer augmentation method, which constitutes the subject of the present investigation. Effect of BTT on heat transfer performance in novel triangular axial corrugated tubes is investigated experimentally and numerically. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The analyses are conducted for Reynolds number extending from 10,000 to 80,000 within the turbulent regime. The shear stress transport model is applied as the turbulence model. Air is used as the working fluid. The typical full-length twisted tapes with two different twist ratios and the broken twisted tape with two different twist ratios, and three gap ratios are used for the comparative analysis. The angular pitch between the two neighboring corrugations and the angle of the corrugation are kept constant through the experiments at 120^° and 60^°, respectively, while three different corrugations heights are analyzed. Eventually, correlations for predicting friction factor and Nusselt number are developed. The thermohydraulic performance is also calculated. The results show a good correspondence with the measurements and the published correlations of other researchers. For all examined cases, the performance factors are always larger than unity.

摘要

在管中插入断裂的扭曲带 (BTT) 是一种新型的被动传热增强方法，它构成了本研究的主题。实验和数值研究了BTT对新型三角形轴向波纹管传热性能的影响。为了增强热工水力性能，提供了一种带插件的波纹管。对湍流状态下从 10,000 到 80,000 的雷诺数进行分析。应用剪应力传递模型作为湍流模型。空气被用作工作流体。采用两种不同捻比的典型全长捻带和两种不同捻比、三种间隙比的断捻带进行对比分析。^°和 60 ^°，同时分析三种不同的波纹高度。最终，开发了预测摩擦系数和努塞尔数的相关性。还计算了热工水力性能。结果显示与其他研究人员的测量结果和已发表的相关性有很好的对应关系。对于所有检查的情况，性能因素总是大于单位。