双铅铋回路自然循环瞬态响应分析

为了研究液态金属双自然循环回路功率变化时的瞬态响应和回路的稳定性,利用SIMULINK在单个铅铋自然循环回路的基础上建立了双自然循环回路模型,并用FLUENT程序进行计算验证,分析了不同升功率和降功率过程中回路的流速振荡及双回路的稳定性。计算结果表明:延长升功率时间可减小流速振荡,且当升功率速率先慢后快时更有利于减小流速振荡和缩短流动到达稳定所需的时间;对于双自然循环回路,当降功率速率不同时,回路的流速均未发生明显的振荡,降功率速率对回路的稳定性影响并不显著。双自然循环回路比单回路更不稳定,通过减小中间换热面的热阻能有效提高双回路的稳定性。

Analysis on Transient Response of Natural Circulation in Coupled LBE Loops

In order to study the transient response of power change in liquid metal coupled natural circulation loops and their stability, a model for analyzing coupled natural circulation loops was established based on the single lead bismuth eutectics (LBE) natural circulation loop by using SIMULINK, and FLUENT code was used to validate the model. The flow oscillations during different processes of increasing power and decreasing power were analyzed. Meanwhile, the stability of coupled loops was also studied. The results show that extending the time for increasing power can reduce the flow oscillations. Furthermore, increasing power more slowly at the beginning will be better for reducing the flow oscillations and the time required to reach steady state. Obvious flow oscillations are not observed in coupled natural circulation loops when the rate of power decrease is different, so the power decrease rate will not influence the stability apparently. Coupled natural circulation loops are more unstable than single loop. On the other hand, they can be stabilized by decreasing the thermal resistance of the intermediate heat transfer surface.