华龙一号非能动安全壳冷却系统循环水箱的热分层现象数值研究

华龙一号核电技术采用了非能动安全壳冷却系统的先进设计。作为一种自然循环系统，系统的冷却能力与其循环水箱的水温直接相关，循环水箱中的热分层现象研究对循环系统冷却能力的准确评估以及工程设计优化均有重要的现实意义。本文基于计算流体力学（CFD）技术对循环水箱升温过程进行了三维流动传热的数值模拟。研究表明，循环水箱中存在较为明显的热分层现象，总体上呈现水池顶部温度波动大，而底部等温层较为平缓的特点，系统循环功率和循环流量均会对水箱的升温过程产生影响：功率增大、流量减小均会促使水箱内产生较明显的热分层现象，同时也会使水箱平均温度偏高，出口水温也相应较高。2列循环系统出现循环功率或流量不均衡对水箱平均温度以及出口温度的升高过程基本无明显影响，因此非能动安全壳冷却系统水箱对系统循环能起到一定的自稳定的效果。

Numerical Simulation on Thermal Stratification in Water Storage Tank of Passive Containment Cooling System for HPR1000

Passive containment cooling system, as one of advanced safety features employed in HPR1000, is a natural circulation system. Since the cooling capacity is highly depended on water temperature in water storage tank, thermal stratification phenomena in water storage tank should be well evaluated and the investigation is also meaningful for engineering design optimization. A transient simulation of heating process on the water storage tank with 3D model was conducted by CFD method in the paper. The results show that thermal stratification occurs in the water storage tank, and the temperature at the top of the pool fluctuates greatly, while at the bottom goes mildly. Both circulation flow rate and power impact temperature increase of water body and thermal stratification in the water storage tank. Higher power and/or fewer flow rate promote thermal stratification and make water temperature in tank and on outlet of system higher. Two trains of cooling systems which run under different conditions have rare impact on formation of thermal stratification in the water storage tank and characteristic temperatures like average temperature and outlet-temperature, which indicates that the water storage tank has self-stability on circulation of passive cooling system.