Effects of vibration conditions, spatial confinement and friction on mixing and segregation characteristics of mixed pebble beds for CFETR WCCB blanket--颗粒学报PARTICUOLOGY

Liu, Y., He, C., Wang, C., Chen, L., & Liu, S. (2024). Effects of vibration conditions, spatial confinement and friction on mixing and segregation characteristics of mixed pebble beds for CFETR WCCB blanket. Particuology, 85, 268-279. https://doi.org/10.1016/j.partic.2023.06.018

Effects of vibration conditions, spatial confinement and friction on mixing and segregation characteristics of mixed pebble beds for CFETR WCCB blanket

Yong Liu ^{a b}, Chongyang He ^c, Cong Wang ^d, Lei Chen ^a *, Songlin Liu ^a

a Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, China
b University of Science and Technology of China, Hefei, 230027, China
c Chengdu University, Chengdu, 610106, China
d Zhejiang Lab, Hangzhou, 310000, China

10.1016/j.partic.2023.06.018

Volume 85, February 2024, Pages 268-279

Received 10 April 2023, Revised 16 June 2023, Accepted 30 June 2023, Available online 13 July 2023, Version of Record 26 July 2023.

E-mail: chlei@ipp.ac.cn

Highlights

• Effects of vibration conditions, spatial confinement and friction on segregation are studied.

• Percolation, convection and diffusion mechanism are responsible for segregation.

• Percolation mechanism predominates when vibration acceleration is low.

• Suppression effect of confinement is affected by threshold of free space height.

• The mixed pebble beds are segregated as the friction coefficient increases.

Abstract

This paper presents the study of the dynamic characteristics of confined mixed pebble beds with different friction under different vibration conditions using the discrete element method. The λ segregation index is used to quantify the degree of particle mixing or segregation. The percolation, convection and diffusion mechanisms are responsible for the segregation patterns of the mixed pebble. The results show the degree of segregation can be suppressed by decreasing the vibration acceleration or free space height below a threshold. Further simulation reveals the threshold of vibration acceleration or free space height both are related to the bed height increment which determines the strength of the percolation mechanism. In addition, the strength of percolation and convection becomes weaker by decreasing the friction of particles and walls, which makes the pebbled bed remains in a mixed state under vibration. These findings are significant to clarify the main factors behind the three segregation mechanisms and hence provide solutions to retaining the mixed state of the Li₂TiO₃&Be₁₂Ti mixed pebble bed.

Graphical abstract

Keywords

Vibration; Segregation; Binary pebble bed; Discrete element method

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