对称双环路倾斜条件下自然循环特性研究

Natural Circulation Characteristics in a Symmetrical Two-Circuit Loop under Inclined Condition

通过理论分析和实验对倾斜条件下多回路传热系统自然循环特性进行研究。实验在一对称双环路自然循环回路上进行,利用海洋工况模拟实验台实现倾斜条件。理论分析与实验结果符合较好。研究结果表明,在一定热负荷下,倾斜使总循环流量低于倾斜前,而冷、热管段温差则高于倾斜前。由于上、下联箱内流体存在密度差,在倾斜条件下将产生垂直于主循环驱动力方向的附加驱动力,使流体产生沿外环流动的趋势,并最终导致支路循环的不平衡性;缩短换热器间距离、增大换热器与加热段距离可以降低倾斜导致的支路不平衡性。

Natural circulation characteristics of an integrated natural circulation reactor were investigated theoretically and experimentally.Experiments were carried out on a test loop that had a symmetric two-circuit configuration.The inclination condition was achieved by a marine condition simulation platform.A series of data,such as the total flow rate,branch flow rates,inlet and outlet temperatures of electrical heater and heat exchangers,were obtained.Both experimental and analytical results showed that under inclination condition the total flow rate was reduced,whereas one branch flow rate was increased; meanwhile the temperature difference between hot leg and cold legs was increased.It is revealed that density difference existed between the up plenum and down plenum,which caused an additional driven force perpendicular to the original one and introduces an outer circulation.Under the co-action of inner and outer circulation,one branch circulation was enhanced and the other was depressed.This unbalance between branch circulations can be alleviated by shortening the distance between heat exchangers and enlarging the distance between the heat exchanger and heating section.