Local heat transfer characteristics of water flowing through a single fracture within a cylindrical granite specimen
Local heat transfer characteristics of water flowing through a single fracture within a cylindrical granite specimen
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DOI：
10.1007/s12665-016-6249-2
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发表时间：
2016-11
影响因子：
2.8
通讯作者：
B. Bai;Yuanyuan He;Xiaochun Li;Shaobin Hu;Xiaoxue Huang;Jun Li;Jia-ling Zhu
中科院分区：
文献类型：
--
作者：
B. Bai;Yuanyuan He;Xiaochun Li;Shaobin Hu;Xiaoxue Huang;Jun Li;Jia-ling Zhu
局部传热系数（LHTC）可以作为描述裂缝局部传热特性的有效指标，但与总体传热系数（OHTC）相比，很少用于研究干热岩石裂缝的局部传热特性。采用数值模拟方法和实验结果相结合的方法，研究了围压作用下花岗岩单裂隙水渗流的LHTC特性。成功地开发了数值模型，并通过试验数据进行了验证。研究发现，局部换热系数与断口形貌的起伏有着密切的关系。在一定的孔径范围内，窄缝具有较高的局部换热能力。对于固定的裂缝孔径，增加流速并没有显着改善裂缝平坦区域的局部传热能力。然而，在粗糙区域，流速具有较高的影响，并且在断裂表面处的凹陷位置具有大得多的LHTC。建立了波纹度与LHTC之间的相关模型。此外，LHTCs和OHTCs之间的比较表明，基于定义的方法提出的OHTCs的最小值，这是最接近相应的LHTCs的算术平均值。
The local heat transfer coefficient (LHTC) can be an effective indicator to describe the local heat transfer characteristics of fractures but has rarely been employed to investigate the local heat exchange properties of a hot dry rock fracture compared to the overall heat transfer coefficient (OHTC). The aim of this paper is to investigate the LHTC of water flowing through a single fracture within a cylindrical granite specimen under confining pressure by combining the numerical modeling approach and the experimental results. A numerical model was successfully developed and verified by the test data. It is found that the local heat transfer coefficient is obviously closely related to the fluctuation of the fracture morphology. Within a certain range of aperture, narrower fracture has higher local heat transfer ability. Increasing the flow rate did not significantly improve the local heat transfer ability in the flat area of the fracture for a fixed fracture aperture. However, at the rougher areas, the flow rate has a higher effect, and the sunken positions at the fracture surface have much larger LHTC. A correlated model was developed to describe the relationship between waviness and LHTC. In addition, a comparison between the LHTCs and the OHTCs shows that the definition-based method presents the smallest values of the OHTCs, which are the closest to the arithmetic mean values of the corresponding LHTCs.