The paper presents an experimental heat transfer enhancement study in a tubular heat exchanger fitted with delta-winglets. The experimental work was conducted by varying the airflow rate in the test tube having a constant wall heat-flux for turbulent regime, Reynolds number (Re) from 5200 to 23,000. Effects of three pitch ratios (PR=P/D=1.5, 2.0 and 3.0) and two attack angles, α = 45° and 60°, of the winglets at a single blockage ratio (BR=b/D = 0.15) on thermal characteristics are examined. The experimental results show that the winglet-inserted tube yields, respectively, the heat transfer, friction factor and thermal performance in the form of TEF around 1.99–4.08, 4.9–14.3 times higher than the plain tube and 0.85–1.85, depending on the operating condition.
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机译：本文提出了一种具有三角翼线的管式热交换器中的实验传热增强研究。通过改变具有恒定壁热通量的试管中的气流速率来进行实验工作，用于湍流状态，雷诺数（RE）从5200到23,000。三个俯仰比（Pr = P / D = 1.5,2.0和3.0）和两个攻击角，π= 45°和60°的效果，在热量上以单个堵塞比（Br = B / D = 0.15）检查特征。实验结果表明，薄翼插入管的产量分别为TEF的形式，比普通管高出1.99-4.08的形式和0.85-1.85操作条件。
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