CFD modeling of natural convection in pebble bed geometry with finite volume method
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Salih Said Çatalbas
and
Ali Tiftikci
Abstract
In this study, we used the finite volume method to computationally model natural convective flow in packed bed geometry. Using the OpenFOAM® v2112 code, we performed the computational analysis. We successfully meshed the intricate packed bed flow geometry, which consists of several spheres positioned at random. The spheres have sizes of 0.006 and 0.01 m, and the associated Rayleigh numbers are 1.83 × 107 and 8.48 × 107 respectively. We used the packed bed heights of H/d = 5, 10, and 20 in the simulations. By comparing the results of the OpenFOAM® v2112 simulations of the natural convection flow for all self-heating sphere in a packed bed, we demonstrated that the velocity distributions and Nusselt values are in good agreement with the experimental data. Additionally, it was evident from the velocity and temperature distributions in a packed bed core that there was a major temperature rise at nearby low velocity fields and a minor velocity rise in the intermediate and upper elevations. We showed that increasing the height of the pebble-bed core and correspondingly increasing the quantity of spheres inside it makes the flow more difficult and also generates local hot spots. This study is notable for using the finite volume method to evaluate natural convection flow in all self-heating packed beds and for simulating packed bed flow using a significant number of spheres. These two factors contribute to the originality of this work.
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Research ethics: Not applicable.
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Author contributions: The authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Competing interests: The authors states no conflict of interest.
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Research funding: This study was co-funded by the Scientific and Technological Research Council of Turkey (TUBITAK) ARDEB 2523 grant no 120N935 and by the Ministry of Science and ICT (MSIT) with National Research Foundation (NRF) (grant codes 2020K2A9A1A06097156).
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Data availability: The raw data can be obtained on request from the corresponding author.
Nomenclature
- CFD
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computational fluid dynamics
- FVM
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finite volume method
- VHTR
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very high temperature reactor
- HTGR
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high temperature gas-cooled reactor
- FCC
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face-centered cubic
- BCC
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body centered cubic
- STL
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standard tessellation language
- CFL
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Courant–Friedrichs–Lewy
- PISO
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pressure-implicit with splitting of operators
- SIMPLE
-
semi-implicit method for pressure-linked equations
- RANS
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Reynolds-averaged Navier Stokes
- DNS
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direct numerical simulations
- PDE
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partial differential equations
- Rad
-
Rayleigh number
- Re
-
Reynolds number
- Pr
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Prandtl number
- Nud
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Nusselt number
-
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mean value of turbulent kinetic energy
- k max
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maximum value of turbulent kinetic energy
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mean value of turbulent shear stress
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maximum value of turbulent shear stress
- H/d
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height to sphere diameter ratio
- U
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z-velocity
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© 2023 Walter de Gruyter GmbH, Berlin/Boston
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Articles in the same Issue
- Frontmatter
- CFD modeling of natural convection in pebble bed geometry with finite volume method
- Experimental investigation of heat transfer characteristics of inclined aluminium two phase closed thermosyphon
- Advances in triple tube heat exchangers regarding heat transfer characteristics of single and two-phase flows in comparison to double tube heat exchangers part 1
- Advances in triple tube heat exchangers regarding heat transfer characteristics of single and two-phase flows in comparison to double tube heat exchangers part 2
- Neutronic and thermal-hydraulic assessment of the TRR with new core designed based on tubular fuels
- A non-dominated discrete differential evolution for fuel loading pattern optimization of a nuclear research reactor
- CFD and machine learning based hybrid model for passive dilution of helium in a top ventilated compartment
- Optimization strategy for SAM in nuclear power plants based on NSGA-II
- Probing 6He induced reactions with nuclear level density
- An application for nonlinear heterogeneity-based isotherm models in characterization of niobium sorption on clay rocks and granite
- Calendar of events
