Abstract

A numerical study is conducted to investigate heat transfer characteristics of supercritical water flowing upward in an inclined smooth tube under uniform heating conditions. In this study, model verification was performed under the conditions of low heat flux and high heat flux to ensure the accuracy of experimental data. Inner wall temperature and heat flux distribute non-uniformly on the circumference due to the influence of natural convection. The increase of heat flux enhances the non-uniform circumferential distribution, while the increase of mass flux reduces the non-uniform circumferential distribution. Heat transfer of upward vertical and inclined flows is compared under low and high heat flux conditions. Radial distributions of fluid temperature, density, specific heat capacity, velocity, and turbulent kinetic energy are presented and analyzed. The analysis shows that the increase of heat flux reduces radial turbulence and heat-absorbing capacity of the boundary fluid, while increases radial temperature and density gradient. Three dimensionless buoyancy parameters are used to evaluate the buoyancy effect of inclined flow.

摘要

通过数值研究研究了在均匀加热条件下，超临界水在倾斜光滑管中向上流动的传热特性。本研究在低热流和高热流条件下进行模型验证，以保证实验数据的准确性。由于自然对流的影响，内壁温度和热通量在圆周上分布不均匀。热通量的增加增强了非均匀的周向分布，而质量通量的增加减少了非均匀的周向分布。比较了低热流和高热流条件下向上垂直流和倾斜流的传热。流体温度、密度、比热容、速度的径向分布，和湍动能进行了介绍和分析。分析表明，热通量的增加降低了边界流体的径向湍流和吸热能力，同时增加了径向温度和密度梯度。三个无量纲浮力参数用于评估倾斜流的浮力效应。