Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Study on the mixing performance of mixing vane grids and mixing coefficient by CFD and subchannel analysis code in a 5×5 rod bundle

  • Bin Han (Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University) ;
  • Xiaoliang Zhu (Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University) ;
  • Bao-Wen Yang (DEQD Institute for Advanced Research in Multiphase Flow and Energy Transfer) ;
  • Aiguo Liu (DEQD Institute for Advanced Research in Multiphase Flow and Energy Transfer) ;
  • Yanyan Xi (Nuclear Fuel Research and Design Center, China Nuclear Power Technology Research Institute Co.,Ltd.) ;
  • Lei Liu (DEQD Institute for Advanced Research in Multiphase Flow and Energy Transfer) ;
  • Shenghui Liu (Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University) ;
  • Junlin Huang (Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University)
  • Received : 2023.02.15
  • Accepted : 2023.06.25
  • Published : 2023.10.25
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Abstract

Mixing Vane Grid (MVG) is one of the most important structures in fuel assembly due to its high performance in mixing the coolant and ultimately increasing Critical Heat Flux (CHF), which avoids the temperature rising suddenly of fuel rods. To evaluate the mixing performance of the MVG, a Total Diffusion Coefficient (TDC) mixing coefficient is defined in the subchannel analysis code. Conventionally, the TDC of the spacer grid is obtained from the combination of experiments and subchannel analysis. However, the processing of obtaining and determine a reasonable TDC is much challenging, it is affected by boundary conditions and MVG geometries. In is difficult to perform all the large and costing rod bundle tests. In this paper, the CFD method was applied in TDC analysis. A typical 5 × 5 MVG was simulated and validated to estimate the mixing performance of the MVG. The subchannel code was used to calculate the TDC. Firstly, the CFD method was validated from the aspect of pressure drop and lateral temperature distribution in the subchannels. Then the effect of boundary conditions including the inlet temperature, inlet velocities, heat flux ratio between hot and cold rods and the arrangement of hot and cold rods on MVG mixing and TDC were studied. The geometric effects on mixing are also carried out in this paper. The effect of vane pattern on mixing was investigated to determine which one is the best to represent the grid's mixing performance.

Keywords

Acknowledgement

The authors would like to express their special thanks for the financial support from Jiangsu Funding Program for Excellent Postdoctoral Talent and the National Natural Science Foundation of China (No. 12205045). The support is gratefully acknowledged.

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