Numerical modeling packing structures of Li4SiO4 pebble bed for HCCB-TBM

doi:10.16568/j.0254-6086.201702008

Abstract

Abstract:

The packing structures of pebble bed under the influence of gravity were studied initially by discrete element method simulation. The results indicate that both the friction coefficient and the restitution coefficient have a great influence on the final packing structure of pebble bed. When the friction coefficient is small, the effects of friction coefficient on the packing structure of pebble bed play a major role. When the friction coefficient is larger, the impacts of restitution coefficient on the packing structure of pebble bed play an important role. There is a transition of pebbles distribution from the regular distribution close to the container walls to the uniformly random distribution in the interior region of the pebble bed. The local packing factor of pebble bed shows an oscillation profile. The amplitude of the oscillation reduces gradually with the increase of distance to the container wall. The distribution of local packing factor presents a wall effect obviously. The packing structures of pebble beds obtained in this work can be used to build a random packing model of pebble bed for the studies of thermal properties of pebble bed and the flow characteristics of purge gas.

Key words: Tritium breeder blanket, Packing factor, Packing structure, Discrete element method

摘要：

通过离散元法初步模拟了微球在重力作用下的堆积行为，并分析了氚增殖区Li₄SiO₄球床的局部堆积结构。研究结果表明，摩擦系数和恢复系数对球床最终堆积结构有很大的影响。当摩擦系数较小时，摩擦系数对球床堆积结构的影响起主要作用；当摩擦系数较大时，恢复系数对球床堆积结构的影响起主要作用。球形颗粒从靠近壁面处的规则分布逐渐过渡到内部区域的均匀随机分布。球床局部堆积因子表现出了明显的壁面效应，其分布随着微球到壁面距离的增加而呈现出振幅逐渐减小的振荡趋势。所得到的球床堆积结构信息可用于研究球床传热特性和提氚气体流动特性的随机堆积球床模型的建立。

关键词: 氚增殖包层, 堆积因子, 堆积结构, 离散元方法

CLC Number:

TL62+7

GONG Bao-ping, FENG Yong-jin, LIU Yang, LIAO Hong-bing, WANG Xiao-yu, FENG Kai-ming. Numerical modeling packing structures of Li4SiO4 pebble bed for HCCB-TBM[J]. NUCLEAR FUSION AND PLASMA PHYSICS, 2017, 37(2): 173-180.

巩保平，冯勇进，刘洋，廖洪彬，王晓宇，冯开明. HCCB-TBM包层Li4SiO4球床堆积结构的数值模拟[J]. 核聚变与等离子体物理, 2017, 37(2): 173-180.

References

[1] 冯开明. ITER实验包层计划综述 [J]. 核聚变与等离子体物理, 2006, 9(3): 161–169.

[2] Giancarlia L M, Abdou M, Campbell D J, et al. Overview of the ITER TBM program [J]. Fusion Engineering and Design, 2012, 87: 395–402

[3] Feng K M, Zhang G S, Hu G, et al. New progress on design and R&D for solid breeder test blanket module in China [J]. Fusion Engineering and Design, 2014, 89: 1119–1125.

[4] Feng Y J, Feng K M, Cao Q X, et al. Current Status of the Fabrication of Li₄SiO₄ and Beryllium Pebbles for CN HCCB TBM in SWIP [J]. Plasma Science and Technology, 2013, 15(3): 291–294.

[5] Mandal D, Sathiyamoorthy D, Vinjamur M. Void fraction and effective thermal conductivity of binary particulate bed [J]. Fusion Engineering and Design, 2013, 88: 216.

[6] Zhao Z, Feng K M, Feng Y J. Theoretical calculation and analysis modeling for the effective thermal conductivity of Li₄SiO₄ pebble bed [J]. Fusion Engineering and Design, 2010, 85: 1975–1980.

[7] Gan Yixiang, Kamlah Marc. Thermo-mechanical modelling of pebble bed-wall interfaces [J]. Fusion Engineering and Design, 2010, 85: 24–32.

[8] Tal Tsory, Nir Ben-Jacob, Tamir Brosh, et al. Thermal DEM-CFD modeling and simulation of heat transfer through packed bed [J]. Powder Technology, 2013, 244: 52.

[9] Ying A, Reimann J, Boccaccinic L, et al. Status of ceramic breeder pebble bed thermo-mechanics R&D and impact on breeder material mechanical strength [J]. Fusion Engine- ering and Design, 2012, 87: 1130–1137.

[10] 汪卫华, 程德胜, 冯开明, 等. 中国HCCB-TBM氚增殖球床热工水力学特性数值模拟 [J]. 核聚变与等离子体物理, 2014, 34(3): 200–206.

[11] 宋娟, 郭海兵, 黄洪文. 增殖剂球床载气体流动特性 [J]. 强激光与粒子束, 2015, 27(1): 016006.

[12] Abou-Sena Ali, Neuberger Heiko, Ihli Thomas. Experimental investigation on the possible techniques of pebbles packing for the HCPB Test Blanket Module [J]. Fusion Engineering and Design, 2009, 84: 355–358.

[13] Reimann J, Abou-Sena Ali, Nippen Rainer, et al. Pebble bed packing in prismatic containers [J]. Fusion Engineering and Design, 2013, 88: 2343–2347.

[14] Cundall P A, Starck O D L. A discrete numerical model for granular assemblies [J]. Geotechnique, 1979, 29(1): 47–65.

[15] An Zhiyong, Ying Alice. Abdou Mohamed, Application of discrete element method to study mechanical behaviors of ceramic breeder pebbled beds [J]. Fusion Engineering and Design, 2007, 82: 2233–2238.

[16] Gan Yixiang, Kamlah Marc, Reimann J. Computer simulation of packing structure in pebble beds [J]. Fusion Engineering and Design, 2010, 85: 1782–1787.

[17] Arno De Klerk. Voidage variation in packed beds at small column to particle diameter ratio [J]. AIChE Journal, 2003, 49(8): 2022–2029.

[18] Antwerpen W V, Toit C G D, Rousseau P G. A review of correlation to model the packing structure and effective thermal conductivity in packed beds of mono-sized spherical particles [J]. Nuclear Engineering and Design, 2010, 240: 1803–1818.

[19] 孙其诚, 王广谦. 颗粒物质力学导论 [M]. 北京: 科学出版社, 2009. 59–72.

[20] Heikki Suikkanen, Jouni Ritvanen, et al. Discrete element modeling of pebble packing in pebble bed reactors [J]. Nuclear Engineering and Design, 2014, 273: 24–32.

[21] Alberto Di Renzo, Francesco Paolo Di Mail. Comparison of contact-force models for the simulation of collision in DEM-based granular flow codes [J]. Chemical Engineering Science, 2004, 59: 525–541.

[22] Kloss C, Goniva C, Hager A, et al. Models, algorithms and validation for open source DEM and CFD-DEM [J]. Progress in Computational Fluid Dynamics, 2012, 12(2/3): 140–152.

[23] 黄青富, 詹美礼, 盛金昌, 等. 基于颗粒离散单元法的获取任意相对密实度下级配颗粒堆积体的数值方法 [J]. 岩土工程学报, 2015, 37(3): 537–543.

[24] 秦志英, 陆启韶. 基于恢复系数的碰撞过程模型分析 [J]. 动力学与控制学报, 2006, 4(4): 294–298.

[25] Gan Yixiang, Kamlah Marc. Discrete element modelling of pebble beds: With application to uniaxial compression tests of ceramic breeder pebble beds [J]. Journal of the Mechanics and Physics of Solids, 2010, 58: 129–144.

[26] 李逸良, 邱信明, 张雄. 恢复系数的不同定义及其适用性分析 [J]. 力学与实践, 2015, 37(6): 773–777.