高温气冷球床堆有效导热系数模型的改进

有效导热系数是高温气冷球床堆热工设计和安全分析程序中的基本参数，ZBS模型广泛应用于球床结构有效导热系数的预测。本文针对ZBS模型中的关键经验型参数——接触面积系数φ进行了分析，通过对不同堆积结构球床有效导热系数的数值分析，获得了12组接触直径比和配位数及其对应的φ值，然后通过多元线性分析获得φ的计算公式。与德国SANA实验结果进行比较，发现改进后的ZBS模型预测能力优于其他模型。改进后的ZBS模型的计算结果与先前实验测量的球床主体区域的有效导热系数吻合也很好。本文研究结果可为高温气冷球床堆的设计和安全分析提供理论支持。

Improvement on Effective Thermal Conductivity Model of High Temperature Pebble Bed Reactor

The effective thermal conductivity is a key parameter in the thermal design and safety analysis of the high temperature pebble bed reactor. The ZBS model is widely used to predict the effective thermal conductivity of pebble bed reactor core. In this paper, the key empirical parameter contact area fraction φ in the ZBS model was analyzed. The effective thermal conductivity in different pebble beds were numerically studied and the twelve groups of the values of φ with the corresponding contact radius ratios and coordination numbers were obtained. Then the formula for calculating contact area fraction φ was obtained through the multiple linear regression. Compared with SANA experimental data, the improved ZBS model is better than other models. Compared with previous experimental data, the improved ZBS model is able to predict the effective thermal conductivity in the bulk region of pebble bed. The results in this paper could provide theoretical guide for the design and safety analysis of the high temperature pebble bed reactor.