Heat Transfer and Fluid Flow Characteristics in Supercritical Pressure Water
Heat Transfer and Fluid Flow Characteristics in Supercritical Pressure Water
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DOI：
10.1115/1.3090817
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发表时间：
2009-07
影响因子：
--
通讯作者：
J. Licht;M. Anderson;M. Corradini
中科院分区：
文献类型：
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作者：
J. Licht;M. Anderson;M. Corradini
在方环形流道中进行了一系列积分传热测量，水温为 175~400°C，向上质量速度为 300 kg/m 2 s 和 1000 kg/m 2 s，热通量为 0、200 kW/m 2 和 440 kW/m 2 ，压力均为 25 MPa。使用二分量激光多普勒测速系统测量的平均速度和湍流速度以及使用计算流体动力学 (CFD) 代码 FLUENT 进行的模拟来解释超临界压力水中传热的恶化和增强。在低质量速度下，积分传热测量表现出较大的局部壁温峰值，无法使用努塞尔相关式准确预测。详细的平均速度和湍流速度以及 FLUENT 模拟表明，浮力效应会导致径向位置处的湍流量显着减少，类似于等温流的壁区域定律。在接近准临界温度的整体温度下，高质量速度积分传热测量表现出增强的传热，其幅度取决于所施加的热通量。在这些条件下，测量的平均速度和湍流速度没有显示出明显的变化。 FLUENT 模拟表明，比热的综合效应可以用来解释观察到的效应。实验测量的传热和局部速度数据还可用作比较现有 CFD 模型的数据库，例如雷诺平均纳维斯托克斯 (RANS) 方程，甚至可能是大涡模拟 (LES) 和直接数值模拟 (DNS)。最终，这些测量将有助于开发能够准确预测超临界压力水传热的模型。
A series of integral heat transfer measurements in a square annular flow passage was performed for bulk water temperatures of 175―400°C with upward mass velocities of 300 kg/m 2 s and 1000 kg/m 2 s and heat fluxes of 0, 200 kW/m 2 , and 440 kW/m 2 , all at a pressure of 25 MPa. Mean and turbulent velocities measured with a two-component laser Doppler velocimetry system along with simulations using the computational fluid dynamics (CFD) code FLUENT were used to explain the deterioration and enhancement of heat transfer in supercritical pressure water. At low mass velocities, the integral heat transfer measurements exhibited large localized wall temperature spikes that could not be accurately predicted with Nusselt correlations. Detailed mean and turbulent velocities along with FLUENT simulations show that buoyancy effects cause a significant reduction in turbulent quantities at a radial location similar to what is the law of the wall region for isothermal flow. At bulk temperatures near the pseudocritical temperature, high mass velocity integral heat transfer measurements exhibited an enhanced heat transfer with a magnitude dependent on the applied heat flux. Measured mean and turbulent velocities showed no noticeable changes under these conditions. FLUENT simulations show that the integrated effects of specific heat can be used to explain the observed effects. The experimentally measured heat transfer and local velocity data also serve as a database to compare existing CFD models, such as Reynolds-averaged Navier-Stokes (RANS) equations and possibly even large Eddy simulations (LES) and direct numerical simulations (DNS). Ultimately, these measurements will aid in the development of models that can accurately predict heat transfer to supercritical pressure water.