Experimental study on heat transfer to the supercritical water upward flow in a vertical tube with internal helical ribs
Experimental study on heat transfer to the supercritical water upward flow in a vertical tube with internal helical ribs
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DOI：
10.1016/j.ijheatmasstransfer.2015.05.109
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发表时间：
2015-10
影响因子：
5.2
通讯作者：
Qing Zhang;Huixiong Li;Weiqiang Zhang;Liangxing Li;X. Lei
中科院分区：
文献类型：
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作者：
Qing Zhang;Huixiong Li;Weiqiang Zhang;Liangxing Li;X. Lei
本文介绍了在Hi-TaP-XJTU试验回路中进行的超临界水（SCW）内螺旋肋垂直管内向上流动换热实验研究的一些结果。实验包括大范围的状态参数：P= 22.5-28 MPa，G= 400-1000 kg/(m2s),q= 300-700 kW/m2。这些数据与已知的光滑管和其他类型的肋管在传热恶化（HTD）和没有它的情况下的数据进行了比较。试验肋管的换热系数（HTC）在不加HTD的情况下分别比光滑管和其他类型的肋管高1.41 ~ 1.85倍和1.34倍。试验肋管高温射流的临界热流密度是光滑管的1.8倍，临界热流密度与质量流密度之比至少是其他类型肋管的1.13倍。在大比热区（LSHR），试验肋管与光滑管的HTC之比显著大于LSHR区域以外的HTC之比。分析了内螺旋肋管强化传热的机理。最后，建立了该管中SCW向上流动的HTC分段相关方程，该方程包括以下三个分离区域的体积流体焓方程：(1)H< 1700 kJ/kg,(2) 1700≥2700 kJ/kg, (3)H> 2700 kJ/kg。它的类型为enu /Nus=CRemPrn，其中enusn是由Mokry-Pioro相关决定的光滑管的努塞尔数，cis是单独焓区的数值常数。
This paper presents some results of experimental research performed at the Hi-TaP-XJTU test loop on heat transfer to the supercritical water (SCW) upward flow in a vertical tube with internal helical ribs. The experiments include a large range of regime parameters:P= 22.5–28 MPa,G= 400–1000 kg/(m2s),q= 300–700 kW/m2. These present data were compared with those known for smooth tubes and other types of ribbed tubes both under the heat transfer deterioration (HTD) and without it. The heat transfer coefficient (HTC) in the test ribbed tube is by 1.41–1.85 and 1.34 times higher as compared with smooth tubes and ribbed tubes of other types in the cases without HTD. The critical heat flux of HTD in the test ribbed tube is 1.8 times of that in the smooth tube, and the ratio of the critical heat flux to the mass flux is at least 1.13 times higher than ribbed tubes of other types. Moreover, the ratio of HTC in the test ribbed tube to that in the smooth tube in the large specific heat region (LSHR) is significantly larger than that beyond the LSHR region. The mechanism of heat transfer enhancement taking place in the tube with internal helical ribs was analyzed as well. Finally, the HTC piecewise correlation for the upward SCW flow in this tube was developed, which includes three equations for the following separated regions of the bulk fluid enthalpy: (1)H< 1700 kJ/kg, (2) 1700 ⩽H⩽ 2700 kJ/kg, (3)H> 2700 kJ/kg. It is of typeNu/Nus=CRemPrn, whereNusis the Nusselt number for a smooth tube determined by the Mokry–Pioro correlation andCis the numerical constant for the separate enthalpy region.