Accuracy of Eulerian-Eulerian, two-fluid CFD boiling models of subcooled boiling flows
Accuracy of Eulerian-Eulerian, two-fluid CFD boiling models of subcooled boiling flows
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DOI：
10.1016/j.ijheatmasstransfer.2016.06.098
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发表时间：
2016-12-01
影响因子：
5.2
通讯作者：
Fairweather, M.
中科院分区：
文献类型：
--
作者：
Colombo, M.;Fairweather, M.
沸腾流动在工业和工程中经常被发现，这是因为在这种流动中可以以最小的温差传递大量的热量。在核工业中，沸腾以不同的方式影响着几乎所有水冷核反应堆的运行。最近，使用计算流体动力学（CFD）的方法来预测沸腾流动正在增加，在核领域，CFD正在开发，以解决热工水力安全问题，如建立临界热通量，这可能是核燃料棒的完整性的主要威胁。在本文中，欧拉欧拉，双流体CFD模型的准确性进行了评估，在一个大型数据库的过冷沸腾流，避免了相当流行的情况下，由个案调整的描述性模型，以有限的实验数量。该模型包括一个雷诺应力湍流模型，基于动量的方法S-gamma粒子数平衡方法和沸腾模型推导出的热流分配方法。该数据库涵盖了水和制冷剂在垂直管道和环形通道中过冷沸腾流动的大范围条件。总的来说，一个令人满意的预测精度是实现了一些感兴趣的量，如空隙率和湍流和液体温度场，但结果是不太令人满意的，在其他领域，更具体地说，平均气泡直径和平均速度分布接近环形通道中的壁。随着大气泡处理、气泡破裂和聚结以及靠近壁面的沸腾区域的改进建模，更具体地说，气泡离开直径、壁面处理和气泡对湍流的贡献方面的进展，一致性可能会得到改善。(C)2016爱思唯尔有限公司版权所有
Boiling flows are frequently found in industry and engineering due to the large amount of heat that can be transferred within such flows with minimum temperature differences. In the nuclear industry, boiling affects in different ways the operation of almost all water-cooled nuclear reactors. Recently, the use of computational fluid dynamic (CFD) approaches to predict boiling flows is increasing and, in the nuclear area, CFD is being developed to solve thermal hydraulic safety issues such as establishing the critical heat flux, which is perhaps the major threat to the integrity of nuclear fuel rods. In this paper, the accuracy of an Eulerian-Eulerian, two-fluid CFD model is evaluated over a large database of subcooled boiling flows, avoiding the rather popular case-by-case tuning of descriptive models to a limited number of experiments. The model includes a Reynolds stress turbulence model, the method of moments-based S-gamma population balance approach and a boiling model derived using the heat flux partitioning approach. The database covers a large range of conditions in subcooled boiling flows of water and refrigerants in vertical pipes and annular channels. Overall, a satisfactory predictive accuracy is achieved for some quantities of interest, such as the void fraction and the turbulence and liquid temperature fields, but results are less satisfactory in other areas, more specifically for the average bubble diameter and the mean velocity profiles close to the wall in annular channels. Agreement may be improved with advances in the treatment of large bubbles and bubble break-up and coalescence, as well as in improved modelling of the boiling region close to the wall, and more specifically the bubble departure diameter, the wall treatment and the contribution of bubbles to turbulence. (C) 2016 Elsevier Ltd. All rights reserved.