• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>International Journal of Heat and Mass Transfer >Heat transfer and pressure drop in the transitional flow regime for a smooth circular tube with twisted tape inserts and a square-edged inlet
【24h】

Heat transfer and pressure drop in the transitional flow regime for a smooth circular tube with twisted tape inserts and a square-edged inlet

机译：光滑的圆形管，带有扭曲的带状插入件和方形入口，在过渡流动状态下的传热和压降

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The purpose of this study was to experimentally investigate the heat transfer and pressure drop characteristics in the transitional flow regime of twisted tape inserts in a circular tube. Experiments were conducted in a circular tube with an internal diameter of 19.0 mm and a length of 5.27 m, and twisted tape inserts with twist ratios of 3, 4 and 5. A square-edged geometry was used at the tube inlet and it was experimentally operated with water flowing through it while the tube was heated with a constant heat flux. The experiments were conducted at three different heat fluxes of 2,3 and 4 kW/m~2. The experimental set-up was operated between Reynolds numbers of 400 and 11400, and the Prandtl numbers varied between 2.9 and 6.7. Two methods were used to identify the transition points of the different heat fluxes and twist ratios. The first method used the standard deviation of the temperature measurements, and the second method used three linear curve fits on a log-log scale. The curve fits made it possible for correlations to be developed for the non-dimensionalised heat transfer coefficients and friction factors, which took twist ratio, heat flux and Reynolds number into consideration. For the same heat flux, it was found that the Colburn j-factors increased as the twist ratios decreased, and transition started earlier. When the twist ratio was kept constant and the heat flux was varied, higher heat fluxes delayed the transition from laminar to transitional flow. The friction factors were found to increase as the twist ratio decreased. When both the twist ratio and the Reynolds number were kept constant, an increase in heat flux was found to decrease the friction factor.
机译：这项研究的目的是实验研究圆形管中扭曲带插入物在过渡流动状态下的传热和压降特性。在内径为19.0 mm，长度为5.27 m的圆形管中进行实验，并使用扭曲比为3、4和5的扭曲带状插入物。在管的入口处使用正方形边缘的几何形状，并进行了实验当管子以恒定的热通量加热时，水流过它。实验在2,3和4 kW / m〜2的三种不同热通量下进行。实验设置在雷诺数400和11400之间进行，普朗特数在2.9和6.7之间变化。使用两种方法来确定不同热通量和扭曲比的转变点。第一种方法使用温度测量值的标准偏差，第二种方法使用对数对数刻度上的三个线性曲线拟合。曲线的拟合使得可以为未量纲的传热系数和摩擦系数建立相关性，并考虑了扭曲比，热通量和雷诺数。对于相同的热通量，发现Colburn的j因子随着扭曲比的降低而增加，并且转变开始得更早。当扭曲比保持恒定且热通量变化时，较高的热通量会延迟从层流到过渡流的过渡。发现摩擦系数随着扭曲比的降低而增加。当扭曲比和雷诺数均保持恒定时，发现热通量的增加会减小摩擦系数。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号