摘要
并联矩形通道间的流动不稳定性现象广泛存在于能源动力、石油和化工等工业系统。对于耦合传热并联矩形通道,其流动传热特性与分离并联矩形通道存在一定差异。为进一步获得耦合传热并联矩形通道的流动不稳定性特性,该文采用系统分析程序RELAP5对已有实验本体进行建模,并基于已有矩形通道流动不稳定性数据开展了计算方法验证,在此基础上探索了并联耦合通道流动不稳定性规律,并对比研究了分离通道与耦合通道的不稳定性边界。结果表明:耦合通道与分离通道的不稳定性边界相近,通道间传热减弱了耦合通道流量振荡幅值,对系统稳定性具有一定的增强作用。
[Objective]Rectangular channels are widely used in energy power,petroleum,and chemical systems due to their compact structure and high heat exchange efficiency.In heat exchangers and reactor cores that use rectangular flow channels,the channels are separated from each other,which could result in instability phenomena under certain working conditions.Existing research shows that the coupling structure can distribute heat among the channels based on their respective heat transfer characteristics.Heat conduction through the wall can reduce the wall temperature fluctuations,reduce peak wall temperatures in the dried-out state,and improve the stability of the system.Given the fact that wall coupling heat transfer between parallel channels improves system stability,this study aims to explore the influence of coupled heat transfer on the flow instability of parallel rectangular channels,which has high research value.[Methods]In this paper,the thermal-hydraulic program REALP5/MOD3.3 was used to analyze the flow instability characteristics of the parallel channel,and the independent and coupled heating conditions were realized by changing the thermal components.The objects used in this paper are parallel rectangular channels with a heating length of 1000 mm and a cross-section of 40.0 mm × 2.0 mm;a coupled heat transfer wall with 40.0,2.0,and 1000.0 in width,thickness,and height,respectively;an axial grid size of 40 mm in size;and a grid size of 0.5 mm in the direction of the thickness of the coupled heat transfer wall.The influence of the coupled heat transfer on the flow instability of parallel channels was studied based on the ratio of heat transfer of the coupling wall and the heat transfer inside the fluid medium during a flow oscillation cycle.Accordingly,the influence of thermal parameters such as system pressure,mass flow rate,and inlet subcooling of the parallel-channel system coupled with heat transfer on the flow instability boundary parameters was studied.[Results](1)The heat transfer through the coupling heat transfer wall was less than that of the fluid in the unstable process,making it difficult to eliminate the flow instability between channels.(2)The instability boundary of the coupled rectangular channel was slightly higher than that of the separation channel due to the influence of heat transfer through the wall,and the stability of the system was higher before instability occurred.(3)The boundary power increased almost linearly as the mass flow rate increased.This was primarily because the length of the single-phase section and the proportion of frictional pressure drop increased with an increase in the mass flow rate.enhancing the overall stability of the system.(4)Given the same pressure and flow rate,the difference in the density of the fluid at the inlet and outlet of the rectangular channel and the accelerated pressure drop decreased,and the stability of the parallel rectangular channel was enhanced with an increase in the inlet subcooling degree.(5)Given the same inlet subcooling degree and flow,with the increase in system pressure,the density and kinematic viscosity differences and frictional pressure drop of the vapor and liquid phases decreased,and the overall stability of the system was enhanced with an increase in the system pressure.[Conclusions]The instability boundary parameters of the coupled and separated rectangular channels are similar;however,the system stability of the coupled rectangular channels is higher before instability occurs.The influence of thermal parameters on the instability boundary is similar for coupled heat transfer parallel rectangular channels and separated channels.Furthermore,increasing the system pressure,mass flow rate,and inlet subcooling can enhance the stability of the system.
作者
胡钰文
闫晓
宫厚军
王艳林
周磊
HU Yuwen;YAN Xiao;GONG Houjun;WANG Yanlin;ZHOU Lei(CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology,Nuclear Power Institute of China,Chengdu 610041,China)
出处
《清华大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2023年第8期1257-1263,共7页
Journal of Tsinghua University(Science and Technology)
作者简介
胡钰文(1990-),男,博士研究生;通信作者:宫厚军,研究员,E-mail:ghjtsing@126.com。
