硝酸盐自然循环回路空冷塔性能分析

Performance analysis of the air cooling tower for nitrate natural circulation loop

硝酸盐自然循环回路(Nitrate Natural Circulation Loop,NNCL)是先进熔盐堆非能动衰变热排出系统的实验回路,目的是获得自然循环下回路的传热、阻力等特性,验证计算分析方法的正确性等。本文采用RNG(Renormalization Group)k-ε湍流模型、增强壁面函数和SIMPLE(Semi-Implicit Method for Pressure Linked Equations)算法,对硝酸盐自然循环回路空冷塔部分的对流换热进行了数值模拟研究。计算结果表明:空冷换热器旁路漏流对换热有较大影响,可以通过旁路挡板增强换热能力,三层旁路挡板的设计能将换热能力提升近一倍。

Background： Nitrate natural convection loop （NNCL） was designed to study the heat transfer behavior and corrosion behavior of direct reactor auxiliary cooling system （DRACS）. DRACS is residual heat removal system of Advanced High-Temperature Reactor （AHTR） whilst the air cooling tower is the ultimate heat sink of DRACS. The structure of salt-to-air heat exchanger and the design of cooling tower are important in determining performance. Purpose： The aim is to study the performance on air cooling tower of nitrate natural convection loop, and finalize the optimization design. Methods： Based on the FLUENT software and structure model of the cooling tower, numerical simulations are carried out to study the heat transfer performance of NNCL. Results： The results show that the by-pass flow will reduce the heat transfer ability. The capacity of heat transfer can be enhanced by installing of the by-pass damper, and 3-layer by-pass damper can increase the capacity of heat transfer by as much as 100%. Conclusion： Numerical simulation can provide some basis for optimizing heat transfer performance of the air cooling tower, and increase the by-pass damper design is necessary to effectively avoid the by-pass flow of air heat exchanger.