In high-temperature gas-cooled reactors, graphite dust particles within the reactor core and the heat transfer equipment experience large temperature gradients. Under such conditions, thermophoresis may play an important role in determining aerosol evolution. This study presents a theoretical and numerical analysis of the thermophoretic effects on aerosol coagulation within these reactors. The coagulation rates for Brownian versus thermophoretic coagulation are calculated and compared for various temperature gradients. Our results show that thermophoretic coagulation dominates over Brownian coagulation for large temperature gradients. We defined an enhancement factor to evaluate the role of thermophoretic coagulation under various reactor conditions. The enhancement factor increased dramatically with increasing temperature gradient, decreasing pressure and increasing particle diameter, but was not very sensitive to temperature change. The time evolution of the particle size distribution related to combined Brownian and thermophoretic coagulation was simulated using a log-skew-normal method of moments. The simulation results indicate that aerosol evolution can be strongly accelerated by thermophoretic coagulation under large temperature gradients.

在高温气冷反应堆中，反应堆堆芯和传热设备内的石墨粉尘会经历较大的温度梯度。在这种条件下，热泳可能在确定气溶胶的演变中起重要作用。这项研究提出了对这些反应堆中的热泳作用对气溶胶凝结作用的理论和数值分析。计算布朗氏凝结与热泳凝结的凝结速率，并比较各种温度梯度。我们的结果表明，在大温度梯度下，热泳凝结作用优于布朗氏凝结作用。我们定义了一个增强因子，以评估在各种反应器条件下热泳凝结的作用。随着温度梯度的增加，增强因子急剧增加，降低压力和增加粒径，但对温度变化不是很敏感。使用对数偏态正态矩法模拟了与布朗氏和热泳凝结相结合的粒度分布随时间的演变。模拟结果表明，在大温度梯度下，热泳凝结可以大大促进气溶胶的释放。