自然循环工况蒸汽发生器一回路流量分配特性分析

Analysis on Flow Distribution Characteristics of Steam Generator under Natural Circulation Condition

自然循环是核动力系统一种特殊运行工况,此时蒸汽发生器内倒U型管束会发生反流现象,从而影响一二次侧换热功率与运行稳定性。本研究开发核动力装置蒸汽发生器内一次侧流量分配计算程序,以芬兰PACTEL压水反应堆实验验证计算程序准确性,并讨论了回路质量流量、管高及一次侧入口温度对倒U型管束蒸汽发生器流量分配的影响。结果表明,倒U型管束的管高越低、一次侧入口温度越低会导致出现反流的临界压降和临界流速越小;相较于倒U型管高度的变化,蒸汽发生器一次侧入口温度的变化更加显著地影响倒U型管束的流量分配;增加循环质量流量可抑制反流现象,随着回路质量流量增加至某一阈值时,倒U型管束反流将不再出现。

Natural circulation is a particular operating condition of nuclear power system,and reversed flow occurs in the inverted U-shaped tube bundle of the steam generator,which affects the heat transfer between the primary and secondary sides and the operation stability.In this research,In this study,the calculation code of primary flow distribution in steam generator of nuclear power unit is developed,and the accuracy of the calculation code is verified by the Finnish PACTEL pressurized water reactor experiment.The effects of loop mass flow,tube height and primary inlet temperature on the flow distribution of inverted U-tube bundle steam generator are discussed.The results show that the lower the tube height and the lower the inlet temperature of the primary side of the inverted U-shaped tube bundle,the smaller the critical pressure drop and critical flow velocity will be.Compared with the change of the height of the inverted U-shaped tube,the change of the inlet temperature of steam generator primary side affects the flow distribution of the inverted U-shaped tube bundle more significantly.The reversed flow could be suppressed by increasing the circulation mass rate,and it will disappear when the mass rate increases to a threshold.