Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Analysis of forced convection in the HTTU experiment using numerical codes

  • M.C. Potgieter (Unit for Energy and Technology Systems, North-West University) ;
  • C.G. du Toit (Unit for Energy and Technology Systems, North-West University)
  • Received : 2023.06.30
  • Accepted : 2023.11.23
  • Published : 2024.03.25
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Abstract

The High Temperature Test Unit (HTTU) was an experimental set-up to conduct separate and integral effects tests of the Pebble Bed Modular Reactor (PBMR) core. The annular core consisted of a randomly packed bed of uniform spheres. Natural convection tests using both nitrogen and helium, and forced convection tests using nitrogen, were conducted. The maximum material temperature achieved during forced convection testing was 1200 ℃. This paper presents the numerical analysis of the flow and temperature distribution for a forced convection test using 3D CFD as well as a 1D systems-CFD computer code. Several modelling approaches are possible, ranging from a fully explicit to a semi-implicit method that relies on correlations of their associated phenomena. For the comparison between codes, the analysis was performed using a porous media approach, where the conduction and radiative heat transfer were lumped together as an effective thermal conductivity and the convective heat transfer was correlated between the solid and gas phases. The results from both codes were validated against the experimental measurements. Favourable results were obtained, in particular by the systems-CFD code with minimal computational and time requirements.

Keywords

Acknowledgement

The authors wish to thank PBMR (Pty) Ltd. For permission to publish part of the work that was done in collaboration with the North-West University and M-Tech Industrial (Pty) Ltd., as well as the respective authors of the works cited.

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