7.6 Summary
499
tion plays a more crucial role in determining the flow pattern in a specific bed. There
is a transition zone for the flow pattern switching from mass flow to funnel flow as
the particle–wall friction increases; keeping particle–wall friction below the lower
bound of the transition zone is an efficient way to ensure the uniform flow field in a
pebble bed.
New criteria for flow pattern evaluation are created. Three characteristic values
concerned with stagnant zones, radial uniformity, and flow sequence, are defined
to evaluate a pebble flow quantitatively. By using these criteria, flow performances
of beds with different friction settings can be distinguished easily. For the practical
pebble bed consisting of a hopper and a cylinder, friction impact on the hopper part
outweighs that of the cylindrical part, so reducing friction between pebbles and the
hopper surface is the priority in engineering.
References
1. Yang, X.T., W.P. Hu, S.Y. Jiang, K.K.L. Wong, and J.Y. Tu. 2012. Mechanism analysis of
quasi-static dense pebble flow in pebble bed reactor using phenomenological approach. Nuclear
Engineering and Design 250: 247–259.
2. Gui, Nan, Xingtuan Yang, Tu Jiyuan, and Shengyao Jiang. 2014. Effect of bed configuration
on pebble flow uniformity and stagnation in the pebble bed reactor. Nuclear Engineering and
Design 270: 295–301.
3. CAmpbell, and S. Charles. 2006. Granular material flows: An overview. Powder Technology
162 (3): 208–229.
4. Xingtuan Yang, Yu., Nan Gui Li, Xinlong Jia, Tu Jiyuan, and Shengyao Jiang. 2014. Some
movement mechanisms and characteristics in pebble bed reactor. Science & Technology of
Nuclear Installations 2014 (3): 1–10.
5. Wójcik, M., J. Tejchman, and G.G. Enstad. 2012. Confined granular flow in silos with inserts—
full-scale experiments. Powder Technology 222 (5): 15–36.
6. Jintao, Wu, Jiang Binbo, Jizhong Chen, and Yongrong Yang. 2009. Multi-scale study of particle
flow in silos. Advanced Powder Technology 20 (1): 62–73.
7. Yang, Shie-Chen, and Shu-San Hsiau. 2001. The simulation and experimental study of granular
materials discharged from a silo with the placement of inserts. Powder Technology 120 (3):
244–255.
8. Marijan Babic, Hayley H. Shen, and Hung Tao Shen. 2006. The stress tensor in granular shear
flows of uniform, deformable disks at high solids concentrations. Journal of Fluid Mechanics
219 (219): 81–118.
9. Campbell, Charles S. 2002. Granular shear flows at the elastic limit. Journal of Fluid Mechanics
465 (465): 261–291.
10. Jiang, S.Y., X.T. Yang, Z.W. Tang, W.J. Wang, J.Y. Tu, Z.Y. Liu, and J. Li. 2012. Experimental and numerical validation of a two-region-designed pebble bed reactor with dynamic core.
Nuclear Engineering and Design 246: 277–285. Selected and expanded papers from International Conference Nuclear Energy for New Europe 2010, Portoro?, Slovenia, September 6-9,
2010.Selected and expanded papers from International Conference Nuclear Energy for New
Europe 2010, Portoro?, Slovenia, September 6-9, 2010.Selected and expanded papers from
International Conference Nuclear Energy for New Europe 2010, Portoro?, Slovenia, September 6-9, 2010.Selected and expanded papers from International Conference Nuclear Energy for
New Europe 2010, Portoro?, Slovenia, September 6-9, 2010.Selected and expanded papers from
International Conference Nuclear Energy for New Europe 2010, Portoro? Slovenia, September
499
tion plays a more crucial role in determining the flow pattern in a specific bed. There
is a transition zone for the flow pattern switching from mass flow to funnel flow as
the particle–wall friction increases; keeping particle–wall friction below the lower
bound of the transition zone is an efficient way to ensure the uniform flow field in a
pebble bed.
New criteria for flow pattern evaluation are created. Three characteristic values
concerned with stagnant zones, radial uniformity, and flow sequence, are defined
to evaluate a pebble flow quantitatively. By using these criteria, flow performances
of beds with different friction settings can be distinguished easily. For the practical
pebble bed consisting of a hopper and a cylinder, friction impact on the hopper part
outweighs that of the cylindrical part, so reducing friction between pebbles and the
hopper surface is the priority in engineering.
References
1. Yang, X.T., W.P. Hu, S.Y. Jiang, K.K.L. Wong, and J.Y. Tu. 2012. Mechanism analysis of
quasi-static dense pebble flow in pebble bed reactor using phenomenological approach. Nuclear
Engineering and Design 250: 247–259.
2. Gui, Nan, Xingtuan Yang, Tu Jiyuan, and Shengyao Jiang. 2014. Effect of bed configuration
on pebble flow uniformity and stagnation in the pebble bed reactor. Nuclear Engineering and
Design 270: 295–301.
3. CAmpbell, and S. Charles. 2006. Granular material flows: An overview. Powder Technology
162 (3): 208–229.
4. Xingtuan Yang, Yu., Nan Gui Li, Xinlong Jia, Tu Jiyuan, and Shengyao Jiang. 2014. Some
movement mechanisms and characteristics in pebble bed reactor. Science & Technology of
Nuclear Installations 2014 (3): 1–10.
5. Wójcik, M., J. Tejchman, and G.G. Enstad. 2012. Confined granular flow in silos with inserts—
full-scale experiments. Powder Technology 222 (5): 15–36.
6. Jintao, Wu, Jiang Binbo, Jizhong Chen, and Yongrong Yang. 2009. Multi-scale study of particle
flow in silos. Advanced Powder Technology 20 (1): 62–73.
7. Yang, Shie-Chen, and Shu-San Hsiau. 2001. The simulation and experimental study of granular
materials discharged from a silo with the placement of inserts. Powder Technology 120 (3):
244–255.
8. Marijan Babic, Hayley H. Shen, and Hung Tao Shen. 2006. The stress tensor in granular shear
flows of uniform, deformable disks at high solids concentrations. Journal of Fluid Mechanics
219 (219): 81–118.
9. Campbell, Charles S. 2002. Granular shear flows at the elastic limit. Journal of Fluid Mechanics
465 (465): 261–291.
10. Jiang, S.Y., X.T. Yang, Z.W. Tang, W.J. Wang, J.Y. Tu, Z.Y. Liu, and J. Li. 2012. Experimental and numerical validation of a two-region-designed pebble bed reactor with dynamic core.
Nuclear Engineering and Design 246: 277–285. Selected and expanded papers from International Conference Nuclear Energy for New Europe 2010, Portoro?, Slovenia, September 6-9,
2010.Selected and expanded papers from International Conference Nuclear Energy for New
Europe 2010, Portoro?, Slovenia, September 6-9, 2010.Selected and expanded papers from
International Conference Nuclear Energy for New Europe 2010, Portoro?, Slovenia, September 6-9, 2010.Selected and expanded papers from International Conference Nuclear Energy for
New Europe 2010, Portoro?, Slovenia, September 6-9, 2010.Selected and expanded papers from
International Conference Nuclear Energy for New Europe 2010, Portoro? Slovenia, September