Experimental investigation of heat transfer in vertical upward and downward supercritical CO2 flow in a circular tube
Experimental investigation of heat transfer in vertical upward and downward supercritical CO2 flow in a circular tube
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DOI：
10.1016/j.ijheatfluidflow.2010.09.001
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发表时间：
2011-02-01
影响因子：
2.6
通讯作者：
Kim, Moo-Hwan
中科院分区：
文献类型：
--
作者：
Kim, Dong Eok;Kim, Moo-Hwan
在内径为4.5 mm的圆管内进行了垂直向上和向下超临界CO2流动的湍流传热实验研究。实验的总体流体温度为 29 至 115 摄氏度，压力为 74.6 至 102.6 bar，局部壁热通量为 38 至 234 kW/m(2)，质量通量为 208 至 874 kg/m(2) s。在中等壁热通量和低质量通量下，垂直向上流动的壁温有明显的峰值，但沿流动方向单调增加，向下流动没有峰值。将实验努塞尔数与参考相关性获得的值的比率与 Bo(*) 和 q(*) 分布进行比较，以观察浮力和流动加速对传热的影响。在本研究的实验范围内，流动加速度主要影响传热现象。基于对湍流边界层剪切应力分布和跨湍流边界层比热显着变化的分析，建立了超临界加压流体垂直向上和向下流动的新传热关系式；这种相关性与各种实验数据集的一致性在 +/- 30% 范围内。 (c) 2010 Elsevier Inc. 保留所有权利。
An experimental investigation of turbulent heat transfer in vertical upward and downward supercritical CO2 flow was conducted in a circular tube with an inner diameter of 4.5 mm. The experiments were performed for bulk fluid temperatures from 29 to 115 degrees C, pressures from 74.6 to 102.6 bar, local wall heat fluxes from 38 to 234 kW/m(2), and mass fluxes from 208 to 874 kg/m(2) s. At a moderate wall heat flux and low mass flux, the wall temperature had a noticeable peak value for vertical upward flow, but increased monotonically along the flow direction without a peak value for downward flow. The ratios of the experimental Nusselt number to the value obtained from a reference correlation were compared with Bo(*) and q(*) distributions to observe the buoyancy and flow-acceleration effects on heat transfer. In the experimental range of this study, the flow acceleration predominantly affected the heat-transfer phenomena. Based on an analysis of the shear-stress distribution in the turbulent boundary layer and the significant variation of the specific heat across the turbulent boundary layer, a new heat-transfer correlation for vertical upward and downward flow of supercritical pressurized fluid was developed; this correlation agreed with various experimental datasets within +/- 30%. (c) 2010 Elsevier Inc. All rights reserved.