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首页> 外文期刊>International Journal of Heat and Mass Transfer >Experimental investigation of condensation heat transfer and pressure drop of R-134a flowing inside dimpled tubes with different dimpled depths
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Experimental investigation of condensation heat transfer and pressure drop of R-134a flowing inside dimpled tubes with different dimpled depths

机译：R-134a在不同凹坑深度的凹坑管内流动时的冷凝传热和压降实验研究

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An experimental investigation is conducted to determine the effect of dimpled depth on the condensation heat transfer coefficient and pressure drop of R-134a flowing inside dimpled tubes. The test condenser is a double tube heat exchanger where the refrigerant flows inside and water flows in the annulus. The inner tube is a 1500 mm long and 8.1 mm inside diameter. The experiments are carried out for one smooth tube and three dimpled tubes having dimpled depth of 0.5, 0.75, and 1.0 mm. For each test tube, several test runs are performed over mass flux range of 300-500 kg/m(2)s, heat flux range of 10-20 kW/m(2), and condensing temperature range of 40-50 degrees C. The experimental results reveal that the dimpled tube presents the significant heat transfer enhancement and pressure drop penalty. The tube with the highest dimpled depth yields the highest heat transfer enhancement and pressure drop penalty up to 83% and 892% higher than those of the smooth tube, respectively. Additionally, the overall performance of dimpled tube is evaluated in term of efficiency index. The new correlations including the effect of dimpled depth, dimpled pitch, and helical pitch on the Nusselt number and friction factor of R-134a in dimpled tube are developed. (C) 2018 Elsevier Ltd. All rights reserved.
机译：进行实验研究以确定凹坑深度对在凹坑管内流动的R-134a的冷凝传热系数和压降的影响。测试冷凝器是一个双管热交换器，制冷剂在其中流动，水在环形空间中流动。内管长1500 mm，内径8.1 mm。对一根光滑管和三个凹陷深度为0.5、0.75和1.0 mm的凹陷管进行实验。对于每个试管，在300-500 kg / m（2）s的质量通量范围，10-20 kW / m（2）的热通量范围和40-50摄氏度的冷凝温度范围内进行了几次测试实验结果表明，波纹管具有明显的传热增强和压降损失的特性。凹坑深度最大的管产生的传热增强和压降损失最高，分别比光滑管高83％和892％。另外，根据效率指标评估了凹坑管的总体性能。开发了包括凹坑深度，凹坑节距和螺旋节距对凹坑管中R-134a的努塞尔数和摩擦系数的影响的新关联。 （C）2018 Elsevier Ltd.保留所有权利。

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