Numerical Investigation of the Effect of Grids and Turbulence Models on Critical Heat Flux in a Vertical Pipe

Numerical simulation has been widely used in nuclear reactor safety analyses to gain insight into key phenomena. The Critical Heat Flux (CHF) is one of the limiting criteria in the design and operation of nuclear reactors. It is a two-phase flow phenomenon, which rapidly decreases the heat transfer...

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Main Authors: Xiaomeng Dong, Zhijian Zhang, Dong Liu, Zhaofei Tian, Guangliang Chen
Format: Article
Language:English
Published: Frontiers Media S.A. 2018-07-01
Series:Frontiers in Energy Research
Subjects:
Online Access:https://www.frontiersin.org/article/10.3389/fenrg.2018.00058/full
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spelling doaj-1b1ab2ff55454fe6b0599e24432187a02020-11-24T21:41:03ZengFrontiers Media S.A.Frontiers in Energy Research2296-598X2018-07-01610.3389/fenrg.2018.00058387631Numerical Investigation of the Effect of Grids and Turbulence Models on Critical Heat Flux in a Vertical PipeXiaomeng Dong0Zhijian Zhang1Dong Liu2Zhaofei Tian3Guangliang Chen4College of Nuclear Science and Technology, Harbin Engineering University, Harbin, ChinaCollege of Nuclear Science and Technology, Harbin Engineering University, Harbin, ChinaNuclear Power Institute of China, Chengdu, ChinaCollege of Nuclear Science and Technology, Harbin Engineering University, Harbin, ChinaCollege of Nuclear Science and Technology, Harbin Engineering University, Harbin, ChinaNumerical simulation has been widely used in nuclear reactor safety analyses to gain insight into key phenomena. The Critical Heat Flux (CHF) is one of the limiting criteria in the design and operation of nuclear reactors. It is a two-phase flow phenomenon, which rapidly decreases the heat transfer performance at the rod surface. This paper presents a numerical simulation of a steady state flow in a vertical pipe to predict the CHF phenomena. The detailed Computational Fluid Dynamic (CFD) modeling methodology was developed using FLUENT. Eulerian two-phase flow model is used to model the flow and heat transfer phenomena. In order to gain the peak wall temperature accurately and stably, the effect of different turbulence models and wall functions are investigated based on different grids. Results show that O type grid should be used for the simulation of CHF phenomenon. Grids with Y+ larger than 70 are recommended for the CHF simulation because of the acceptable results of all the turbulence models while Grids with Y+ lower than 50 should be avoided. To predict the dry-out position accurately in a fine grid, Realizable k-ε model with standard wall function is recommended. These conclusions have some reference significance to better predict the CHF phenomena of vertical pipe. It can also be expanded to rod bundle of Boiling Water Reactor (BWR) by using same pressure condition.https://www.frontiersin.org/article/10.3389/fenrg.2018.00058/fullnumerical investigationCritical heat fluxturbulence modelswall functionsgrids distribution
collection DOAJ
language English
format Article
sources DOAJ
author Xiaomeng Dong
Zhijian Zhang
Dong Liu
Zhaofei Tian
Guangliang Chen
spellingShingle Xiaomeng Dong
Zhijian Zhang
Dong Liu
Zhaofei Tian
Guangliang Chen
Numerical Investigation of the Effect of Grids and Turbulence Models on Critical Heat Flux in a Vertical Pipe
Frontiers in Energy Research
numerical investigation
Critical heat flux
turbulence models
wall functions
grids distribution
author_facet Xiaomeng Dong
Zhijian Zhang
Dong Liu
Zhaofei Tian
Guangliang Chen
author_sort Xiaomeng Dong
title Numerical Investigation of the Effect of Grids and Turbulence Models on Critical Heat Flux in a Vertical Pipe
title_short Numerical Investigation of the Effect of Grids and Turbulence Models on Critical Heat Flux in a Vertical Pipe
title_full Numerical Investigation of the Effect of Grids and Turbulence Models on Critical Heat Flux in a Vertical Pipe
title_fullStr Numerical Investigation of the Effect of Grids and Turbulence Models on Critical Heat Flux in a Vertical Pipe
title_full_unstemmed Numerical Investigation of the Effect of Grids and Turbulence Models on Critical Heat Flux in a Vertical Pipe
title_sort numerical investigation of the effect of grids and turbulence models on critical heat flux in a vertical pipe
publisher Frontiers Media S.A.
series Frontiers in Energy Research
issn 2296-598X
publishDate 2018-07-01
description Numerical simulation has been widely used in nuclear reactor safety analyses to gain insight into key phenomena. The Critical Heat Flux (CHF) is one of the limiting criteria in the design and operation of nuclear reactors. It is a two-phase flow phenomenon, which rapidly decreases the heat transfer performance at the rod surface. This paper presents a numerical simulation of a steady state flow in a vertical pipe to predict the CHF phenomena. The detailed Computational Fluid Dynamic (CFD) modeling methodology was developed using FLUENT. Eulerian two-phase flow model is used to model the flow and heat transfer phenomena. In order to gain the peak wall temperature accurately and stably, the effect of different turbulence models and wall functions are investigated based on different grids. Results show that O type grid should be used for the simulation of CHF phenomenon. Grids with Y+ larger than 70 are recommended for the CHF simulation because of the acceptable results of all the turbulence models while Grids with Y+ lower than 50 should be avoided. To predict the dry-out position accurately in a fine grid, Realizable k-ε model with standard wall function is recommended. These conclusions have some reference significance to better predict the CHF phenomena of vertical pipe. It can also be expanded to rod bundle of Boiling Water Reactor (BWR) by using same pressure condition.
topic numerical investigation
Critical heat flux
turbulence models
wall functions
grids distribution
url https://www.frontiersin.org/article/10.3389/fenrg.2018.00058/full
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