Experimental research on reverse flow phenomenon in natural circulation with equal height difference under low flow rate

doi:10.11949/0438-1157.20190407

Abstract

Abstract:

Natural circulation systems are widely used in nuclear power plants due to their inherent safety. Natural circulation system with equal height different is a special system, because its heating section and water tank are connected by upper and lower horizontal loops. However, the phenomenon that the water in water tank reversely flows to the upper horizontal loop will be occurred in this kind of natural circulation system under low flow rate conditions. The studies of this phenomenon are not common. The reverse flow characteristics of upper horizontal loop is researched by visualization experiments. The results show that the reverse flow length in the upper horizontal loop decreases with the increase of flow rate, and increases with the increase of temperature difference between the outlet fluid of heater and the reverse flow fluid form water tank. It is found that the reverse flow in the upper horizontal loop is mainly affected by the inertia force of the hot water and the buoyancy force formed by the hot water and the reverse flow fluid. In addition, the reverse flow phenomenon in the upper horizontal loop can be judged by Richardson number.

Key words: flow, heat conduction, hydrodynamics, equal height difference natural circulation, visualization, reverse flow phenomenon, Richardson number

摘要：

自然循环系统由于具有固有安全性而被广泛应用于核电站中。等高差自然循环系统是一种特殊的系统，其加热段与水箱之间是通过上下水平段连接。在低流量条件下，这类自然循环系统会发生水箱冷水倒流至上水平段的现象，目前对该现象的研究并不常见。对等高度差自然循环系统的上水平段倒流特性进行了可视化实验研究。实验结果表明，上水平段倒流长度随流量的增加而减小，随着加热段出口流体与倒流流体温差的增大而增加。研究发现，上水平段倒流现象主要受加热段出口流体惯性力和与倒流流体形成的浮升力共同影响，并且倒流现象的发生可以通过Richardson数来判定。

关键词: 流动, 热传导, 流体动力学, 等高差自然循环, 可视化, 倒流现象, Richardson数

CLC Number:

TK 124

Jianchuang SUN, Xiaxin CAO, Xu RAN, Zhuohua ZHANG, Zhengpeng MI, Ming DING. Experimental research on reverse flow phenomenon in natural circulation with equal height difference under low flow rate[J]. CIESC Journal, 2019, 70(11): 4231-4237.

孙建闯, 曹夏昕, 冉旭, 张卓华, 米争鹏, 丁铭. 低流量下等高差自然循环系统倒流现象实验研究[J]. 化工学报, 2019, 70(11): 4231-4237.

Figures/Tables 10

Fig.1 Natural circulation system with equal height difference

Table 1 Geometric dimensions of experimental equipment

参数	数值/m
上水平段长度,L_u	1.92
可视化管直径,D	0.05
水箱液位,h	0.5
热电偶间距,d	0.3
水箱长度,L	2.0
水箱宽度,W	2.0
水箱高度,H	3.0

Fig.2 Structural sketch of three-point thermocouple

Fig.3 Fluid temperature distribution in visualization horizontal loop under different flow rates at 40 kW

Fig.4 Flow states in visualization horizontal loop under different flow rates at 40 kW

Fig.5 Fluid temperature distribution in visualization horizontal loop under different flow rates at 50 kW

Fig.6 Flow states in visualization horizontal loop under different flow rates at 50 kW

Fig.7 Fluid temperature distribution in visualization horizontal loop under different temperature differences at 42 kW

Fig.8 Results of experiment and CFD simulation

Fig.9 Richardson number distribution at different powers

References 31

1	吕应中. 大规模替代化石及其他有限能源的固有安全高温核动力[J]. 核科学与工程, 2011, 31(1): 1-8.
	LyuY Z. An inherently-safe high-temperature nuclear energy producing process for the replacement of fossil and other depletive energy on a large scale [J]. Chinese Journal of Nuclear Science and Engineering, 2011, 31(1): 1-8.
2	侯晓凡, 孙中宁, 孙秋南, 等. 开式自然循环系统中间歇喷泉流动的实验研究[J]. 哈尔滨工程大学学报, 2016, 37(4): 556-561.
	HouX F, SunZ N, SunQ N, et al. Experimental study on geysering in an open natural circulation system[J]. Journal of Harbin Engineering University, 2016, 37(4): 556-561.
3	鄢炳火, 于雷, 张杨伟, 等. 简谐海洋条件下自然循环运行特性[J]. 原子能科学技术, 2009, 43(3): 230-236.
	YanB H, YuL, ZhangY W, et al. Natural circulation operational characteristics under ocean condition[J]. Atomic Energy Science and Technology, 2009, 43(3): 230-236.
4	ManeraA, van der HagenT H J J. Stability of natural-circulation-cooled boiling water reactors during startup: experimental results[J]. Nuclear Technology, 2003, 143(1): 77-88.
5	ManeraA, RohdeU, PrasserH M, et al. Modeling of flashing-induced instabilities in the start-up phase of natural-circulation BWRs using the two-phase flow code FLOCAL[J]. Nuclear Engineering and Design, 2005, 235(14): 1517-1535.
6	BragtD D B V, KruijfW J M D, ManeraA, et al. Analytical modeling of flashing-induced instabilities in a natural circulation cooled boiling water reactor[J]. Nuclear Engineering and Design, 2002, 215(1/2): 87-98.
7	van der HagenT H J J, StekelenburgA J C. The low-power low-pressure flow resonance in a natural circulation cooled boiling water reactor[J]. Nuclear Engineering and Design, 1997, 177(1/2/3): 229-238.
8	陈景, 高祖瑛. 简化沸水堆(SSBWR-200)的热工设计和事故分析[J]. 清华大学学报(自然科学版), 2001, 41(6): 52-55.
	ChenJ, GaoZ Y. Thermal-hydraulic design and accident analysis of small simplified BWR (SSBWR-200)[J]. Journal of Tsinghua University (Science and Technology), 2001, 41(6): 52-55.
9	严育华, 高祖瑛, 郑文祥, 等. 小型热电联供沸水堆CR-200研究[J]. 清华大学学报, 1995, 35(6): 83-88.
	YanY H, GaoZ Y, ZhengW X, et al. Preliminary study on small cogeneration BWR CR-200[J]. Journal of Tsinghua University, 1995, 35(6): 83-88.
10	吴莘馨, 姜胜耀, 吴少融, 等. 喷泉不稳定诱发间歇流量振荡实验研究[J]. 核动力工程, 1997, 18(2): 124-128.
	WuX X, JiangS Y, WuS R, et al. Experimental investigation on geysering induced intermittent flow oscillation[J]. Nuclear Power Engineering, 1997, 18(2): 124-128.
11	王建军, 杨星团, 姜胜耀. HRTL-5自然循环稳态特性[J]. 原子能科学技术, 2008, 42(5): 434-437.
	WangJ J, YangX T, JiangS Y. Steady-state behaviors of natural circulation in HRTL-5[J]. Atomic Energy Science and Technology, 2008, 42(5): 434-437.
12	WangJ H, SunY L, WangJ J, et al. Numerical study of nuclear coupled two-phase flow instability in natural circulation system under low pressure and low quality[J]. Nuclear Engineering & Design, 2011, 241(12): 4972-4977.
13	WangJ J, YangX T, JiangS Y. Simulation of flow excursion and thermal siphon under natural circulation condition with lower pressure and lower quality[J]. Nuclear Power Engineering, 2007, 2(2): 169-173.
14	YangX T, JiangS Y, ZhangY J. Analysis of characteristic curves for natural circulation flow excursion at low steam quality conditions[J]. Nuclear Power Engineering, 2006, 27(1): 47-52.
15	JiangS Y, WuX X, ZhangY J. Experimental study of two-phase flow oscillation in natural circulation[J]. Nuclear Science and Engineering, 2000, 135(2): 177-189.
16	侯晓凡, 孙中宁, 范广铭, 等. 开式自然循环系统启动特性研究[J]. 原子能科学技术, 2015, 49(10): 1772-1777.
	HouX F, SunZ N, FanG M, et al. Experimental investigation of startup characteristics in open natural circulation system[J]. Atomic Energy Science and Technology, 2015, 49(10): 1772-1777.
17	HouX F, SunZ N, SuJ Q, et al. An investigation on flashing instability induced water hammer in an open natural circulation system[J]. Progress in Nuclear Energy, 2016, 93: 418-430.
18	GuoX Q, SunZ N, WangJ J, et al. Numerical simulation of the transient behaviors in an open natural circulation system with a large scale[J]. Annals of Nuclear Energy, 2015, 77: 83-93.
19	BaiJ H, ZhaoB, WangJ J. Study on the performance of an open-loop passive containment cooling system[J]. Journal of Nuclear Science and Technology, 2017, 55(1): 1-9.
20	GuoX Q, SunZ N, WangJ J, et al. Simulating investigations on the start-up of the open natural circulation system[J]. Nuclear Engineering and Design, 2015, 289: 35-48.
21	InadaF, FuruyaM, YasuoA. Thermo-hydraulic instability of boiling natural circulation loop induced by flashing (analytical consideration)[J]. Nuclear Engineering and Design, 2000, 200(1/2): 187-199.
22	朱智强, 阎昌琪, 王建军, 等. 棒束通道内自然循环流动阻力特性[J]. 化工学报, 2018, 69(4): 1398-1404.
	ZhuZ Q, YanC Q, WangJ J, et al. Flow resistance characteristics in rod bundle channel under natural circulation condition[J]. CIESC Journal, 2018, 69(4): 1399-1403.
23	TanS C, SuG H, GaoP Z. Experimental study on two-phase flow instability of natural circulation under rolling motion condition[J]. Annals of Nuclear Energy, 2009, 36(1): 103-113.
24	ZhangW C, TanS C, GaoP Z, et al. Study on chaotic characteristics of natural circulation flow instability under rolling motion[J]. Atomic Energy Science and Technology, 2012, 46(6): 705-709.
25	ChenX B, GaoP Z, TanS C, et al. An experimental investigation of flow boiling instability in a natural circulation loop[J]. International Journal of Heat and Mass Transfer, 2018, 117: 1125-1134.
26	JainV, NayakA K, VijayanP K, et al. Experimental investigation on the flow instability behavior of a multi-channel boiling natural circulation loop at low-pressures[J]. Experimental Thermal and Fluid Science, 2010, 34(6): 776-787.
27	俞冀阳, 贾宝山. 一种反应堆非能动余热排出系统的方案设计[J]. 核科学与工程, 2003, 23(1): 32-38.
	YuJ Y, JiaB S. Study of one design of passive residual heat removal system of nuclear reactor[J]. Chinese Journal of Nuclear Science and Engineering, 2003, 23(1): 32-38.
28	俞冀阳, 俞尔俊, 贾宝山. 核反应堆非能动余热排出系统分析[J]. 核安全, 2004, (4): 35-39.
	YuJ Y, YuE J, JiaB S. Analyses on passive residual heat removal system of nuclear reactors [J]. Nuclear Safety, 2004, (4): 35-39.
29	王飞, 彭新建, 杨祖毛, 等. 位差对系统自然循环能力的影响实验研究[J].核动力工程, 2002, 23(4): 25-28.
	WangF, PengX J, YangZ M, et al. Experimental investigation of effect of height difference on natural circulation capability[J]. Nuclear Power Engineering, 2002, 23(4): 25-28.
30	HeF, YangJ L, WangX F. Condensation-induced steam bubble collapse in a pipeline[J]. Tsinghua Science & Technology, 2012, 5(4): 424-427.
31	NaeeniN, YaghoubiM. Analysis of wind flow around a parabolic collector (2): Heat transfer from receiver tube [J]. Renewable Energy, 2007, 32(8): 1259-1272.

[1]	Jiahao SONG, Wen WANG. Study on coupling operation characteristics of Stirling engine and high temperature heat pipe [J]. CIESC Journal, 2023, 74(S1): 287-294.
[2]	Chao HU, Yuming DONG, Wei ZHANG, Hongling ZHANG, Peng ZHOU, Hongbin XU. Preparation of high-concentration positive electrolyte of vanadium redox flow battery by activating vanadium pentoxide with highly concentrated sulfuric acid [J]. CIESC Journal, 2023, 74(S1): 338-345.
[3]	Mingkun XIAO, Guang YANG, Yonghua HUANG, Jingyi WU. Numerical study on bubble dynamics of liquid oxygen at a submerged orifice [J]. CIESC Journal, 2023, 74(S1): 87-95.
[4]	Ruitao SONG, Pai WANG, Yunpeng WANG, Minxia LI, Chaobin DANG, Zhenguo CHEN, Huan TONG, Jiaqi ZHOU. Numerical simulation of flow boiling heat transfer in pipe arrays of carbon dioxide direct evaporation ice field [J]. CIESC Journal, 2023, 74(S1): 96-103.
[5]	Shaohua ZHOU, Feilong ZHAN, Guoliang DING, Hao ZHANG, Yanpo SHAO, Yantao LIU, Zheming GAO. Experimental study of flow noise in short tube throttle valve and noise reduction measures [J]. CIESC Journal, 2023, 74(S1): 113-121.
[6]	Yifei ZHANG, Fangchen LIU, Shuangxing ZHANG, Wenjing DU. Performance analysis of printed circuit heat exchanger for supercritical carbon dioxide [J]. CIESC Journal, 2023, 74(S1): 183-190.
[7]	He JIANG, Junfei YUAN, Lin WANG, Guyu XING. Experimental study on the effect of flow sharing cavity structure on phase change flow characteristics in microchannels [J]. CIESC Journal, 2023, 74(S1): 235-244.
[8]	Yaxin ZHAO, Xueqin ZHANG, Rongzhu WANG, Guo SUN, Shanjing YAO, Dongqiang LIN. Removal of monoclonal antibody aggregates with ion exchange chromatography by flow-through mode [J]. CIESC Journal, 2023, 74(9): 3879-3887.
[9]	Jiaqi YUAN, Zheng LIU, Rui HUANG, Lefu ZHANG, Denghui HE. Investigation on energy conversion characteristics of vortex pump under bubble inflow [J]. CIESC Journal, 2023, 74(9): 3807-3820.
[10]	Song HE, Qiaomai LIU, Guangshuo XIE, Simin WANG, Juan XIAO. Two-phase flow simulation and surrogate-assisted optimization of gas film drag reduction in high-concentration coal-water slurry pipeline [J]. CIESC Journal, 2023, 74(9): 3766-3774.
[11]	Kaijie WEN, Li GUO, Zhaojie XIA, Jianhua CHEN. A rapid simulation method of gas-solid flow by coupling CFD and deep learning [J]. CIESC Journal, 2023, 74(9): 3775-3785.
[12]	Yubing WANG, Jie LI, Hongbo ZHAN, Guangya ZHU, Dalin ZHANG. Experimental study on flow boiling heat transfer of R134a in mini channel with diamond pin fin array [J]. CIESC Journal, 2023, 74(9): 3797-3806.
[13]	Yuanchao LIU, Bin GUAN, Jianbin ZHONG, Yifan XU, Xuhao JIANG, Duan LI. Investigation of thermoelectric transport properties of single-layer XSe₂(X=Zr/Hf) [J]. CIESC Journal, 2023, 74(9): 3968-3978.
[14]	Yan GAO, Peng WU, Chao SHANG, Zejun HU, Xiaodong CHEN. Preparation of magnetic agarose microspheres based on a two-fluid nozzle and their protein adsorption properties [J]. CIESC Journal, 2023, 74(8): 3457-3471.
[15]	Lei XING, Chunyu MIAO, Minghu JIANG, Lixin ZHAO, Xinya LI. Optimal design and performance analysis of downhole micro gas-liquid hydrocyclone [J]. CIESC Journal, 2023, 74(8): 3394-3406.