Radiation Physics and Engineering
A peer-reviewed journal published by K. N. Toosi University of Technology

Numerical and CFD analysis of inclination angle effects on natural circulation mini-loop performance

Document Type : Research Article

Authors

Sayed Abolhasan Nourashrafeddin
Mohsen Shayesteh

Department of Physics, Faculty of Science, Imam Hossein University, Tehran, Iran

https://doi.org/10.22034/rpe.2024.476581.1240
Abstract
This research simulated the natural circulation in a mini-loop using numerical calculations performed with a FORTRAN code and CFD simulations via Ansys Fluent. A stability map of the loop was derived, and the impact of the loop’s inclination angle on this stability map was examined. The findings indicate that at low power levels, particularly functional powers, the loop’s inclination angle does not significantly affect the stability map. The results of the numerical calculations were compared with Vijayan's experimental corrections for this mini-loop, showing good agreement within its functional power range. Additionally, a comparison was made between the numerical calculations and the Ansys Fluent simulation results, which also demonstrated a good agreement, thereby confirming the accuracy of the calculations. Two significant thermo-hydraulic parameters -the mass flow rate and temperature difference at the two heater heads- were calculated and compared for different loop inclinations. It was observed that increasing the inclination angle results in a decrease in the fluid’s mass flow rate and an increase in the temperature difference at the ends of the heat source. Notably, it was determined that achieving a specific temperature difference across the heat source does not necessarily require adjusting the power levels; simply changing the inclination angle is sufficient. Another important result of this research is that by making a series of straightforward assumptions, one-dimensional computations can be solved very precisely, thereby saving computation time.

Highlights

  • Natural circulation in a mini-loop and stability map of a closed loop is investigated.
  • The influence of the angle of inclination of the loop on the stability map is studied.
  • Effect of loop inclination angle on the mass flow rate and on the temperature difference across heater is studied

Keywords

Mini-loop
Natural circulation
Ansys Fluent
Inclination angles
Fortran code
Thermo-hydraulic parameters
Numerical calculations
Adarsh, R., Raveesh, G., and Rupesh, S. (2020). Orifice enabled flow stabilization of natural circulation loop at lower inclinations. Kerntechnik, 85(3):140–146.
Ahmed, N. M., Gao, P., and Bello, S. (2020). Natural circulation systems in nuclear reactors: advantages and challenges. In IOP Conference Series: Earth and Environmental Science, volume 467, page 012077. IOP Publishing.
ANSYS (2024). ANSYS fluent tutorial guide. Canonsburg, PA.
Bejjam, R. B. and Kiran Kumar, K. (2019). Numerical investigation to study the effect of loop inclination angle on thermal performance of nanofluid-based single-phase natural circulation loop. International Journal of Ambient Energy, 40(8):885–893.
Bocanegra, J. A., Marchitto, A., and Misale, M. (2022). Thermal performance investigation of a mini natural circulation loop for solar PV panel or electronic cooling simulated by lattice boltzmann method. Int. J. EQ, 5:1–12.
Borreani, W., Chersola, D., Lomonaco, G., et al. (2017). Assessment of a 2D CFD model for a single phase natural circulation loop. Int. J. Heat Technol., 35(Special Issue 1):S300–S306.
Chen, K. (1985). On the oscillatory instability of closed-loop thermosyphons.
Chen, Y. and Yang, Z. (2022). Probability Safety Analysis for Nuclear Power Plant Long-Term Temporary Shutdown State. In International Conference on Nuclear Engineering, volume 86489, page V013T13A021. American Society of Mechanical Engineers.
Garibaldi, P. and Misale, M. (2008). Experiments in single-phase natural circulation miniloops with different working fluids and geometries.
Ghorbanali, Z. and Talebi, S. (2020). Investigation of a nanofluid-based natural circulation loop. Progress in Nuclear Energy, 129:103494.
IAEA (2021). Natural circulation in advanced water-cooled reactors: Recent developments and future directions (IAEA-TECDOC-1861). International Atomic Energy Agency (IAEA).
Karami, I. and Aghaie, M. (2017). Sensitivity analysis of numerical schemes in natural cooling flows for low power research reactors. Advances in Energy Research, 5(3):255.
Kim, K. M., Jeong, Y. S., Kim, I. G., et al. (2016). Development of passive in-core cooling system for nuclear safety using hybrid heat pipe. Nuclear Technology, 196(3):598–613.
Luo, Q., Zhou, Y., Huang, J., et al. (2024). A review of supercritical fluid flow instability. Progress in Nuclear Energy, 176:105376.
Marchitto, A. and Misale, M. (2018). Mathematical modelling of engineering problems. Journal homepage: http://iieta.org/Journals/MMEP, 5(3):161–167.
Misale, M. (2014). Overview on single-phase natural circulation loops. In Proc. of the intl. Conf. on advances in mechanical and automation engineering–MAE, volume 2014.
Misale, M., Garibaldi, P., Passos, J., and De Bitencourt, G. G. (2007). Experiments in a single-phase natural circulation mini-loop. Experimental Thermal and Fluid Science, 31(8):1111–1120.
Moussavian, S. K., Misale, M., DAuria, F., et al. (2003). Stability behavior of single-phase natural circulation loop. In ASME International Mechanical Engineering Congress and Exposition, volume 37157, pages 119–131.
Nourashrafeddin, S. A., Shayesteh, M., and Bahonar, M. (2023a). Investigating the influence of inclination angle on thermohydraulic parameters of natural circulation laboratory mini-loop. Iranian Nuclear Conference.
Nourashrafeddin, S. A., Shayesteh, M., and Bahonar, M. (2023b). Simulation and investigation of the thermohydraulic parameters of the natural circulation loop of the university of genoa. Iranian Nuclear Conference.
Vijayan, P., Nayak, A., Saha, D., et al. (2008). Effect of Loop Diameter on the Steady State and Stability Behaviour of Single-Phase and Two-Phase Natural Circulation Loops. Science and Technology of Nuclear Installations, 2008(1):672704.
Vijayan, P., Sharma, M., and Saha, D. (2007). Steady state and stability characteristics of single-phase natural circulation in a rectangular loop with different heater and cooler orientations. Experimental Thermal and Fluid Science, 31(8):925–945.
Zhu, H., Yang, X., Lian, H., et al. (2013). Experimental and Numerical Study on Natural Circulation Under Inclined Condition. In International Conference on Nuclear Engineering, volume 55799, page V002T03A021. American Society of Mechanical Engineers.
Zweibaum, N. (2015). Experimental validation of passive safety system models: Application to design and optimization of fluoride-salt-cooled, high-temperature reactors. University of California, Berkeley.
Radiation Physics and Engineering
Volume 6, Issue 2
Winter 2025
Pages 23-34

  • Receive Date 02 September 2024
  • Revise Date 04 November 2024
  • Accept Date 08 November 2024

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