In this study, the heat transfer characteristics of supercritical water in a horizontal double-pipe were investigated via experiments and numerical simulations. The influence of pressure (23 MPa, 25 MPa and 28 MPa) and mass flow rates (540 kg·h^-1, 573 kg·h^-1 and 604 kg·h^-1) were studied by experiments at the inlet temperature of tube 563 K, the inlet temperature of shell varying from 626 K to 756 K. The influence of unilateral mass flow rates varying from 273 kg·h^-1 to 873 kg·h^-1 and the local heat transfer characteristics were studied via numerical simulations. The Shear-Stress Transport $k-\omega$ (SST) model and four selected models have been validated against experiments. The Comparison suggests that Shear-Stress Transport $k-\omega$ (SST) model exhibited the best prediction. The results indicated that the effect of the pressure on heat transfer coefficients depends on bulk temperature, and the coefficients increase with the mass flow rate. When the fluid approaches pseudo-critical temperature, the heat transfer is improved. Nevertheless, the peak heat transfer coefficient occurs at a bulk temperature that is slightly higher than the pseudo-critical point. This phenomenon is strongly correlated with the specific heat of the near-wall fluid, and it is mainly caused by a temperature imbalance between the bulk and the near-wall fluid of the shell side. The imbalance is due to a significant bulk temperature difference between the tube and the shell or a small mass flow rate of the shell side. Finally, the overall value of the local heat transfer coefficient is determined by the fluid temperature of the near-wall region.

在这项研究中，通过实验和数值模拟研究了超临界水在水平双管中的传热特性。的压力（23兆帕，25兆帕和28兆帕）的质量的影响和流速（540公斤·H ^-1，573公斤·H ^-1和604公斤·H ^-1）通过实验进行了研究，在管的入口温度563 K，壳体的入口温度在626 K至756 K之间。通过数值模拟研究了单侧质量流量从273 kg·h ^-1到873 kg·h ^-1的影响以及局部传热特性。剪力运输$ķ--\omega$（SST）模型和四个选定的模型已针对实验进行了验证。比较表明，剪力运输$ķ--\omega$（SST）模型表现出最好的预测。结果表明，压力对传热系数的影响取决于整体温度，并且系数随质量流量的增加而增加。当流体接近伪临界温度时，传热得到改善。然而，峰值传热系数出现在整体温度上，该整体温度略高于伪临界点。该现象与近壁流体的比热密切相关，并且主要由壳侧的本体和近壁流体之间的温度不平衡引起。这种不平衡是由于管与壳体之间的体积温度差很大或壳体侧面的质量流量较小所致。最后，