Abstract: A heat transfer analysis model of pebble beds is established based on discrete element method and computational fluid dynamics coupling method (DEM-CFD). The validation of DEM model, grid sensitivity analysis and heat transfer model are carried out. Based on the above model, the effective thermal conductivity of Li₂TiO₃ pebble beds with particle size distribution, unitary Li₂TiO₃ pebble beds and binary Li₂TiO₃ pebble beds is further simulated and calculated. The influence of particle size distribution, different particle sizes and mixing on the effective thermal conductivity of Li₂TiO₃ pebble beds is studied. The results show that for the Li₂TiO₃ pebble beds with similar packing factor, the effective thermal conductivity of Li₂TiO₃ pebble beds with particle size distribution is similar with unitary Li₂TiO₃ pebble beds with equivalent particle size. In the case of negligible radiation heat transfer, the effect of particle size on the effective thermal conductivity of unitary pebble bed is negligible. Compared with unitary Li₂TiO₃ pebble bed, the binary Li₂TiO₃ pebble bed has higher packing factor and effective thermal conductivity.

Key words: Discrete element method-computational fluid dynamics, Effective thermal conductivity of pebble beds, Particle size distribution, Tritium breeder blankets, Binary pebble bed, Particle size distribution

摘要： 针对聚变堆固态包层的产氚载体中锂陶瓷颗粒组成的氚增殖球床，建立了基于离散元-计算流体力学(DEM-CFD)方法的球床传热分析模型，进行了离散元(DEM)几何模型有效性验证、网格敏感性分析和计算流体力学(CFD)传热模型有效性验证。用该模型模拟计算了粒径分布球床、不同粒径的一元球床、二元球床的有效热导率，研究了相同填充率下，粒径分布、不同粒径及粒径混合对球床有效热导率的影响。研究结果表明，对于填充率相近的钛酸锂球床，粒径分布球床与一元等效粒径球床的有效热导率结果相差不大；在辐射换热可以忽略的情况下，粒径尺寸对一元球床有效热导率的影响可以忽略不计；二元混合钛酸锂球床相较于一元钛酸锂球床有更高的球床填充率和有效热导率。

关键词: 离散元-计算流体力学方法, 球床有效热导率, 粒径分布, 氚增殖包层, 二元球床, 粒径分布