• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Heat Transfer >Entropy Generation in Laminar and Turbulent Natural Convection Heat Transfer From Vertical Cylinder With Annular Fins
【24h】

Entropy Generation in Laminar and Turbulent Natural Convection Heat Transfer From Vertical Cylinder With Annular Fins

机译：环形鳍片垂直圆柱在层流和自然对流换热中的熵产生

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

Entropy generation due to natural convection has been calculated for a wide range of Rayleigh number (Ra) in both laminar (10~4≤Ra≤10~8) and turbulent (10~(10)≤Ra≤10~(12)) flow regimes, for diameter ratio of 2 ≤D/d≤5,for an isothermal vertical cylinder fitted with annular fins. In the laminar regime, the entropy generation was predominantly caused by heat transfer (conduction and convection) and the viscous contribution was negligible with respect to heat transfer. But in the turbulent regime, entropy generation due to fluid friction is significant enough although heat transfer entropy generation is still dominant. The results demonstrate that the degree of irreversibility is higher in case of finned configuration when compared with unfinned one. With the deployment of a merit function combining the first and second laws of thermodynamics, we have tried to delineate the thermodynamic performance of finned cylinder with natural convection. So, we have defined the ratio (I/Q)_(finned)/(I/Q)_(unfinned). The ratio (I/Q)_(finned)/(I/Q)_(unfinned) gets its minimum value at optimum fin spacing where maximum heat transfer occurs in turbulent flow, whereas in laminar flow the ratio (I/Q)_(finned)/(I/Q)_(unfinned) decreases continuously with the increase in number of fins.
机译：在层流（10〜4≤Ra≤10〜8）和湍流（10〜（10）≤Ra≤10〜（12））的大范围瑞利数（Ra）中计算了自然对流产生的熵直径比为2≤D/d≤5的流态，用于装有环形翅片的恒温立式圆柱体。在层流状态下，熵的产生主要是由热传递（传导和对流）引起的，而对于热传递的粘性贡献可以忽略不计。但是在湍流状态下，尽管传热熵产生仍然占主导地位，但由于流体摩擦产生的熵足够显着。结果表明，与未翅片相比，翅片构造的不可逆度更高。通过结合热力学第一定律和第二定律的优点函数的部署，我们试图用自然对流来描绘翅片圆柱的热力学性能。因此，我们定义了比率（I / Q）_（finned）/（I / Q）_（unfinfin）。 （I / Q）_（翅片）/（I / Q）_（未翅片）的比值在最佳翅片间距下达到最小值，在最佳翅片间距下，湍流中的传热最大，而在层流中，（I / Q）_ （鳍）/（I / Q）_（未鳍）随着鳍数量的增加而连续减小。

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