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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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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