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首页> 外文期刊>International Journal of Heat and Mass Transfer >Improved heat transfer and flow resistance achieved with drag reducing Cu nanofluids in the horizontal tube and built-in twisted belt tubes
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Improved heat transfer and flow resistance achieved with drag reducing Cu nanofluids in the horizontal tube and built-in twisted belt tubes

机译：通过减少水平管和内置扭曲带管中的铜纳米流体的阻力来改善传热和流动阻力

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摘要

Experimental studies were performed to investigate drag reducing nanofluids' convective heat transfer coefficient and flow resistance coefficient at Reynolds numbers ranging from 2000 to 18000. Added 0-0.5% mass fraction of Cu nanoparticles into a concentration of 100-400 mg·kg~(-1) cetyl trimethyl ammonium chloride (CTAC), which is a drag reducing fluid. The ratio of two kinds of fluids was explored to find a suitable composition and preparation to define their overall convective heat transfer and flow characteristics. Results indicated that the addition of sodium salicylate (NaSal) in CTAC with deionized water creates an improved drag reducing fluid with stability. When the drag reducing fluid concentration reached 200 mg·kg~(-1), it reached its optimum drag reducing performance in horizontal tube experiments. Experiments with built-in twisted belt tubes resulted in a much improved convective heat transfer characteristic. Results showed using drag reducing Cu nanofluids the heat transfer coefficient will be approximately twice as large as that found in a horizontal tube and the flow resistance coefficient is approximately ten times greater. However, even though built-in twisted belt tubes can enhance heat transfer, they also increase flow resistance. Heat transfer and flow resistance correlations of the drag reducing Cu nanofluids in a horizontal tube and built-in twisted belt tubes were compared with final results showing the calculated and experimental values to be in good agreement. When Cu nanoparticle mass fraction is 0.4%, drag reducing Cu nanofluid has the best heat transfer and drag reducing characteristics. Finally, the overall K factor performance were greater than 1 at different concentrations, which indicated their convective heat transfer enhancing effect was stronger than the reducing flow resistance effect so that they can be used to solve the problem of heat transfer deterioration for drag reducing fluids.
机译：进行了实验研究，研究了减阻纳米流体在2000〜18000雷诺数下的对流换热系数和流阻系数。添加0-0.5％质量分数的Cu纳米粒子至100-400 mg·kg〜（- 1）十六烷基三甲基氯化铵（CTAC），它是一种减阻流体。探索了两种流体的比例，以找到合适的组成和制备方法，以定义它们的整体对流传热和流动特性。结果表明，将CTAC中的水杨酸钠（NaSal）与去离子水一起添加可产生改善的减阻流体，且具有稳定性。当减阻液浓度达到200 mg·kg〜（-1）时，在水平管实验中达到了最佳减阻性能。内置扭曲带管的实验大大改善了对流换热特性。结果显示，使用减阻Cu纳米流体，传热系数将约为水平管的两倍，而流阻系数则约为十倍。但是，即使内置的扭曲带管可以增强热传递，它们也会增加流动阻力。将水平管和内置扭曲带管中的减阻Cu纳米流体的传热和流阻相关性与最终结果进行了比较，表明计算值和实验值吻合良好。当Cu纳米颗粒的质量分数为0.4％时，减阻Cu纳米流体具有最佳的传热和减阻特性。最后，在不同浓度下，总的K因子性能都大于1，这表明它们的对流传热增强作用比降低流阻效应要强，因此它们可用于解决减阻流体传热恶化的问题。

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