原子能科学技术 ›› 2020, Vol. 54 ›› Issue (3): 429-435.DOI: 10.7538/yzk.2019.youxian.0304

• 反应堆工程 • 上一篇    下一篇

应用于管壳式换热器热工水力数值模拟的多孔介质算法

陆道纲;王雨;袁博;隋丹婷   

  1. 华北电力大学 核科学与工程学院,北京102206;非能动核能安全技术北京市重点实验室,北京102206;长江勘测规划设计研究院,湖北 武汉430010
  • 出版日期:2020-03-20 发布日期:2020-03-20

Porous Media Algorithm for Thermal-hydraulic Numerical Simulation of Shell and Tube Heat Exchanger

LU Daogang;WANG Yu;YUAN Bo;SUI Danting   

  1. School of Nuclear Science and Engineering, North China Electric Power University, Beijing 102206, China;Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, Beijing 102206, China;Changjiang Institute of Survey, Planning, Design and Research, Wuhan 430010, China
  • Online:2020-03-20 Published:2020-03-20

摘要:

管壳式换热器是工程中应用最为广泛的换热器类型。换热器壳侧多为复杂的气液两相流,使用精确网格对有上千根传热管的大型管壳式换热器进行模拟较难实现。为实现对壳侧两相流体整体的数值计算,目前最常用的是引入多孔介质模型以减少计算网格数量。多孔介质的两个重要参数是体积孔隙率和表面渗透率。关于多孔系数的计算以前的研究人员已提出了一些方法,但这些方法或直接将体积孔隙率设置为常数,计算精度不够,或计算精度良好,但方法较为繁琐。因此本文提出了一种计算快速且精度高的适用于管壳式换热器热工水力数值模拟的多孔介质系数计算方法GTG(grid combined with tube geometry)。该方法基于网格和换热管位置关系计算体积孔隙率,同时基于区域缩短法计算表面渗透率。可实现对直角坐标和柱坐标的大型管壳式换热器各向异性的多孔介质系数自动生成,且多孔系数可随网格方案改变而自动更新。将GTG方法计算的多孔系数与利用CAD测量的真实值进行对比验证,最大误差仅为4.5%,说明该方法计算精度良好。又基于GTG方法对蒸汽发生器二次侧进行了数值模拟,计算结果与同类研究结果符合良好,表明该方法有效。

关键词: 多孔介质模型, 体积孔隙率, 表面渗透率, 管壳式换热器, 气液两相流

Abstract:

The shell and tube heat exchanger is widely used in engineering. The shell side is mostly complex steam-liquid two-phase flow, and it is difficult to simulate the heat exchanger with thousands of heat transfer tubes using precise grids. In order to realize numerical simulation of shell side, porous media model is commonly applied to reduce computational grids numbers. The volume porosity and surface permeability are two important parameters of porous media, and previous researchers have proposed several methods to calculate them. However, these methods either directly set volume porosity as a constant, which are not accurate enough, either are tedious even have good precision. Hence, a fast and accurate calculation algorithm named GTG (grid combined with tube geometry) was proposed in this paper. The volume porosity was calculated using this method based on the position relationships between grids and heat exchange tubes and the surface permeability was got based on the regional shortening method. It applied for rectangular and cylindrical coordinates. The porous coefficients can be updated automatically with the change of grid scheme. For verifying its correctness, porous coefficients calculated by GTG method were compared with the real values measured by CAD. The maximum error is only 4.5%, which indicates that the calculation accuracy is good. And a numerical simulation of the secondary side in steam generator was developed based on GTG method. The simulation results are in good agreement with the results of similar studies, which explains that the method is effective.

Key words: porous media model, volume porosity, surface permeability, shell and tube heat exchanger, steam-liquid two-phase fluid