6.4 Summary
441
area size is larger, all pebbles flow out of the bed in the shortest time. This means a
smaller stagnant zone and shorter total retention time. It is also found that increasing
the side pebble density would reduce the stagnant zone and total detention time.
Finally, through the study of the velocity field, it can be observed that pebble density
significantly affects the speed of vertical slow. And the axial velocity profiles show
different patterns between the bottom and upper part of the packed bed.
References
1. Choi, Jaehyuk, Arshad Kudrolli, Rodolfo R. Rosales, and Martin Z. Bazant. 2004. Diffusion
and mixing in gravity-driven dense granular flows. Physical Review Letters 92 (17): 174301.
2. Xingtuan YANG, Wenping HU, and Shengyao JIANG. Experimental investigation on feasibility of two-region-designed pebble-bed high-temperature gas-cooled reactor. Journal of Nuclear
Science & Technology, 46(4):374–381, 2009.
3. 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.
4. K Foroutan-pour, P Dutilleul, and D.L Smith. Advances in the implementation of the boxcounting method of fractal dimension estimation. Applied Mathematics and Computation,
105(2):195 – 210, 1999.
5. Gui, Nan, Jianren Fan, and Kefa Cen. 2010. A macroscopic and microscopic study of particle
mixing in a rotating tumbler. Chemical Engineering Science 65 (10): 3034–3041.
6. Gui, Nan, and Jianren Fan. 2015. Numerical study of heat conduction of granular particles in
rotating wavy drums. International Journal of Heat and Mass Transfer 84: 740–751.
7. Jun Ai, Jian Fei Chen, J. Michael Rotter, and Y. Ooi Jin. Assessment of rolling resistance
models in discrete element simulations. Powder Technology, 206(3):269–282, 2011.
8. Iwashita, Kazuyoshi, and Masanobu Oda. 1998. Rolling resistance at contacts in simulation of
shear band development by dem. Journal of Engineering Mechanics 124 (3): 285–292.
9. Tian, F., M. Zhang, H. Fan, M. Gu, L. Wang, and Y. Qi. 2007. Numerical study on microscopic
mixing characteristics in fluidized beds via dem. Fuel Processing Technology 88: 187–198.
10. Hao, Wu, Nan Gui, Xingtuan Yang, Tu Jiyuan, and Shengyao Jiang. 2016. Effects of particle
size and region width on the mixing and dispersion of pebbles in two-region pebble bed.
Granular Matter 18 (4): 76.
11. Li, Yu., Nan Gui, Xingtuan Yang, Tu Jiyuan, and Shengyao Jiang. 2016. Numerical study
of gravity-driven dense granular flows on flow behavior characterization. Powder Technology
297: 144–152.
12. Xinlong Jia, Nan Gui, Hao Wu, Xingtuan Yang, Jiyuan Tu, and Shengyao Jiang. Numerical
study and analysis of the effects of recirculation flow rates in drained pebble flow. Powder
Technology, 314:608 – 619, 2017. Special Issue on Simulation and Modelling of Particulate
Systems.
13. Gui, N., X.T. Yang, J.Y. Tu, and S.Y. Jiang. 2014. A simple geometrical model for analyzing
particle dispersion in a gravity-driven monolayer granular bed. Powder Technology 254: 432–
438.
14. JIANG, Y S., YANG, T X., TANG, W Z., WANG, J W., TU, and Y J. Experimental and
numerical validation of a two-region-designed pebble bed reactor with dynamic core. Nuclear
Engineering & Design, 246(4):277–285, 2012.
441
area size is larger, all pebbles flow out of the bed in the shortest time. This means a
smaller stagnant zone and shorter total retention time. It is also found that increasing
the side pebble density would reduce the stagnant zone and total detention time.
Finally, through the study of the velocity field, it can be observed that pebble density
significantly affects the speed of vertical slow. And the axial velocity profiles show
different patterns between the bottom and upper part of the packed bed.
References
1. Choi, Jaehyuk, Arshad Kudrolli, Rodolfo R. Rosales, and Martin Z. Bazant. 2004. Diffusion
and mixing in gravity-driven dense granular flows. Physical Review Letters 92 (17): 174301.
2. Xingtuan YANG, Wenping HU, and Shengyao JIANG. Experimental investigation on feasibility of two-region-designed pebble-bed high-temperature gas-cooled reactor. Journal of Nuclear
Science & Technology, 46(4):374–381, 2009.
3. 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.
4. K Foroutan-pour, P Dutilleul, and D.L Smith. Advances in the implementation of the boxcounting method of fractal dimension estimation. Applied Mathematics and Computation,
105(2):195 – 210, 1999.
5. Gui, Nan, Jianren Fan, and Kefa Cen. 2010. A macroscopic and microscopic study of particle
mixing in a rotating tumbler. Chemical Engineering Science 65 (10): 3034–3041.
6. Gui, Nan, and Jianren Fan. 2015. Numerical study of heat conduction of granular particles in
rotating wavy drums. International Journal of Heat and Mass Transfer 84: 740–751.
7. Jun Ai, Jian Fei Chen, J. Michael Rotter, and Y. Ooi Jin. Assessment of rolling resistance
models in discrete element simulations. Powder Technology, 206(3):269–282, 2011.
8. Iwashita, Kazuyoshi, and Masanobu Oda. 1998. Rolling resistance at contacts in simulation of
shear band development by dem. Journal of Engineering Mechanics 124 (3): 285–292.
9. Tian, F., M. Zhang, H. Fan, M. Gu, L. Wang, and Y. Qi. 2007. Numerical study on microscopic
mixing characteristics in fluidized beds via dem. Fuel Processing Technology 88: 187–198.
10. Hao, Wu, Nan Gui, Xingtuan Yang, Tu Jiyuan, and Shengyao Jiang. 2016. Effects of particle
size and region width on the mixing and dispersion of pebbles in two-region pebble bed.
Granular Matter 18 (4): 76.
11. Li, Yu., Nan Gui, Xingtuan Yang, Tu Jiyuan, and Shengyao Jiang. 2016. Numerical study
of gravity-driven dense granular flows on flow behavior characterization. Powder Technology
297: 144–152.
12. Xinlong Jia, Nan Gui, Hao Wu, Xingtuan Yang, Jiyuan Tu, and Shengyao Jiang. Numerical
study and analysis of the effects of recirculation flow rates in drained pebble flow. Powder
Technology, 314:608 – 619, 2017. Special Issue on Simulation and Modelling of Particulate
Systems.
13. Gui, N., X.T. Yang, J.Y. Tu, and S.Y. Jiang. 2014. A simple geometrical model for analyzing
particle dispersion in a gravity-driven monolayer granular bed. Powder Technology 254: 432–
438.
14. JIANG, Y S., YANG, T X., TANG, W Z., WANG, J W., TU, and Y J. Experimental and
numerical validation of a two-region-designed pebble bed reactor with dynamic core. Nuclear
Engineering & Design, 246(4):277–285, 2012.