含空气蒸汽冷凝换热特性的数值模拟分析
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摘要
为定量考察气体流速、壁面过冷度、换热面高度和气体压力对含空气蒸汽冷凝换热的影响,本文采用数值模拟的方法进行了分析。计算了基于COPAIN试验装置和CFD软件STAR-CCM+中的扩散理论冷凝模型,在主流流速0. 1~3 m/s、壁面过冷度4℃~50℃、换热面高度0. 5~6 m以及气体压力0. 1~0. 6 MPa的条件下讨论了冷凝换热特性。研究表明:冷凝换热系数在主流流速小于0. 5 m/s的自然对流主导区内几乎不受速度的影响,换热系数相对偏差在6. 7%以内;壁面过冷度的幂指数可用空气质量份额和过冷度的函数来表示且幂指数范围为-0. 008 3~-0. 367;换热面高度在1 m以内时对冷凝换热性能有明显影响;不同蒸汽质量份额条件下,冷凝换热系数与压力的0. 64次方成正比。通过对计算结果的分析得到了冷凝传热性能与各影响因素之间的量化关系,这对进一步认识含空气蒸汽冷凝现象有一定的指导意义。
Numerical simulations are conducted to quantitatively evaluate the effects of gas velocity,wall sub-cooling,condensation wall height,and gas pressure on condensation heat transfer. The calculations are based on COPAIN experimental facility and diffusion theory-based condensation model incorporated in the CFD software STARCCM +. Condensation heat transfer property is evaluated in terms of velocity from 0. 1 m/s to 3 m/s,wall subcooling from 4 ℃ to 50 ℃,condensation wall height from 0. 5 to 6 m,and pressure from 0. 1 MPa to 0. 6 MPa.Results indicate that the condensation heat transfer coefficient is hardly affected by the mainstream gas velocity in the natural convection-dominated region with velocities less than 0. 5 m/s. Furthermore,the power exponent of wall sub-cooling can be described by a function in terms of air mass fraction and wall sub-cooling,which ranges from-0. 008 3 to-0. 367. The condensation wall height has an obvious effect on the condensation heat transfer when it is less than 1 m,and the heat transfer coefficient has a 0. 64 power direct proportion to the gas pressure.Via numerical results analysis,the quantitative relationship between the condensation heat tranfer porperty and the influencing parameters were concluded,which can to a certain degree promote the understanding of steam condensaiton phenomena in the presence of air.
Numerical simulations are conducted to quantitatively evaluate the effects of gas velocity,wall sub-cooling,condensation wall height,and gas pressure on condensation heat transfer. The calculations are based on COPAIN experimental facility and diffusion theory-based condensation model incorporated in the CFD software STARCCM +. Condensation heat transfer property is evaluated in terms of velocity from 0. 1 m/s to 3 m/s,wall subcooling from 4 ℃ to 50 ℃,condensation wall height from 0. 5 to 6 m,and pressure from 0. 1 MPa to 0. 6 MPa.Results indicate that the condensation heat transfer coefficient is hardly affected by the mainstream gas velocity in the natural convection-dominated region with velocities less than 0. 5 m/s. Furthermore,the power exponent of wall sub-cooling can be described by a function in terms of air mass fraction and wall sub-cooling,which ranges from-0. 008 3 to-0. 367. The condensation wall height has an obvious effect on the condensation heat transfer when it is less than 1 m,and the heat transfer coefficient has a 0. 64 power direct proportion to the gas pressure.Via numerical results analysis,the quantitative relationship between the condensation heat tranfer porperty and the influencing parameters were concluded,which can to a certain degree promote the understanding of steam condensaiton phenomena in the presence of air.
引文
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[3]潘丽强,宿吉强,范广铭,等.含空气的蒸汽冷凝传热模型研究[J].核动力工程,2015,36(6):45-50.PAN Liqiang,SU Jiqiang,FAN Guangming,et al. Study on steam/air condensation heat transfer model[J]. Nuclear power engineering,2015,36(6):45-50.
[4]李军,刘长亮,李晓明.非能动安全壳冷却系统设计研究[J].核科学与工程,2018,38(04):632-639.LI Jun,LIU Changliang,LI Xiaoming. Study on the design of passive containment cooling system[J]. Nuclear science and engineering,2018,38(04):632-639.
[5]李军,李晓明,喻新利,等.非能动安全壳热量导出系统设计方案及评价[J].原子能科学技术,2018,52(6):1021-1027.LI Jun,LI Xiaoming,YU Xinli et al. Design and evaluation of passive containment heat removal system[J]. Atomic energy science and technology,2018,52(6):1021-1027.
[6]白晋华,赵博.基于Relap5的非能动安全壳热量导出系统优化[J].核动力工程,2017,38(6):14-17.BAI Jihua,ZHAO Bo. Optimization of design on passive containment cooling system by using relap5 code[J]. Nuclear power engineering,2017,38(6):14-17.
[7]TONG Pan,FAN Guangming,SUN Zhongning,et al. An experimental investigation of pure steam and steam-air mixtures condensation outside a vertical pin-fin tube[J].Experimental thermal and fluid science,2015,69:141-148.
[8]DE LA ROSA J,ESCRIVA,HERRANZ L,et al. Review on condensation on the containment structures[J].Progress in nuclear energy,2009,51(1):32-66.
[9]宿吉强,孙中宁,范广铭,等.含不凝性气体的蒸汽冷凝传热实验研究[J].核动力工程,2014,35(1):36-41.SU Jiqiang,SUN Zhongning,FAN Guangming et al. Analysis of experiments for vertical out-tube steam condensation in presence of non-condensable gases[J]. Nuclear power engineering,2014,35(1):36-41.
[10]DEHBI A. A unified correlation for steam condensation rates in the presence of air-helium mixtures under naturally driven flows[J]. Nuclear engineering and design,2016,300:601-609.
[11]LIU H,TODREAS N E,DRISCOLL M J. An experimental investigation of a passive cooling unit for nuclear plant containment[J]. Nuclear engineering and design,2000,199(3):243-255.
[12]SU Jiqiang,SUN Zhongning,FAN Guangming,et al. Experimental study of the effect of non-condensable gases on steam condensation over a vertical tube external surface[J]. Nuclear engineering and design,2013,262:201-208.
[13]LEE Y,JANG Y,CHOI D. An experimental study of air-steam condensation on the exterior surface of a vertical tube under natural convection conditions[J]. International journal of heat and mass transfer,2017,104:1034-1047.
[14]UCHIDA H,OYAMA A,TOGO Y. Evaluation of postincident cooling systems of light-water power reactors[C]//Proceedings of the Third International Conference on the Peaceful Uses of Atomic Energy. Geneva. 1965:93-104.
[15]KAWAKUBO M,ARITOMI M,KIKURA H,et al. An experimental study on the cooling characteristics of passive containment cooling systems[J]. Journal of nuclear science and technology,2009,46(4):339-345.
[16]DEHBI A. The effects of non-condensable gases on steam condensation under turbulence natural convection conditions[D]. Cambridge:Massachusetts Institute of Technology,1990.
[17]GREEN J,ALMENAS K. An overview of the primary parameters and methods for determining condensation heat transfer to containment structures[J]. Nuclear safety,1996,37:26-48.
[18]BEJAN A. Convection heat transfer[M]. 4th ed. Hoboken:John Wiley&Sons,2013.
[19]CHENG X,BAZIN P,CORNET P,et al. Experimental data base for containment thermal hydraulic analysis[J].Nuclear engineering and design, 2001, 204(1/3):267-284.