塔式太阳能熔盐吸热器传热特性及?分析
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摘要
该文建立了塔式光热电站圆柱形外露管式吸热器(external cylindrical receiver,ECR)的二维传热模型。重点分析了非均匀入射能流、入射能流总功率、环境风速以及吸热管尺寸等运行设计参数对吸热器表面的温度及热损分布、热效率、压降特性和?效率的影响。结果表明:辐射和对流热损主要集中在吸热器后半部的高温区域,若镜场投入辐射集中在熔盐进口区域,将导致熔盐升温过快,高温区域增大,造成更大的热损失;小管径吸热器有更高的热效率以及更小的环境对流热损,但同时会带来更大的压降损失,在直径小于2cm后压降的增幅尤为明显。考虑环境风速与运行功率的影响,?效率随管径显著变化,并存在最优值,随着入射能流总功率的增大,?效率最优值随管径增大而增大。该文的工作可为目前主流商业化塔式电站用外露管柱式吸热器的设计计算以及辐射能流分布的优化提供理论参考。
In this paper, a detailed 2D model of the external cylindrical receiver was presented. The characteristics of thermal efficiency, pressure drop and exergy efficiency, which is influenced by the operating and design parameters such as non-uniform heat flux, total incident power, ambient wind speeds and pipe diameters, were analyzed. The results show that radiation heat loss and convective heat loss mainly concentrate upon the high temperature region at the rear half of the receiver. If the heat flux is concentrated on the area of inlet,will cause the molten salt temperature rises too fast and led to a greater heat loss due to the high temperature region of the tube plate become larger. The small tube gets a better heat transfer efficiency and a smaller convection heat loss, but at the same time, it causes a greater pressure drop. When the diameter is less than 2 cm, the increase of pressure drop is particularly obvious. Combined pressure drop and thermal efficiency, the best exergy efficiency achieved, with the increase of the total incident power, the optimal value of exergy efficiency is appears in the bigger pipe case. The analysis of the related mechanism in this paper can provide a reference for the design and optimization of the radiative heat flux of the external cylindrical receiver.
In this paper, a detailed 2D model of the external cylindrical receiver was presented. The characteristics of thermal efficiency, pressure drop and exergy efficiency, which is influenced by the operating and design parameters such as non-uniform heat flux, total incident power, ambient wind speeds and pipe diameters, were analyzed. The results show that radiation heat loss and convective heat loss mainly concentrate upon the high temperature region at the rear half of the receiver. If the heat flux is concentrated on the area of inlet,will cause the molten salt temperature rises too fast and led to a greater heat loss due to the high temperature region of the tube plate become larger. The small tube gets a better heat transfer efficiency and a smaller convection heat loss, but at the same time, it causes a greater pressure drop. When the diameter is less than 2 cm, the increase of pressure drop is particularly obvious. Combined pressure drop and thermal efficiency, the best exergy efficiency achieved, with the increase of the total incident power, the optimal value of exergy efficiency is appears in the bigger pipe case. The analysis of the related mechanism in this paper can provide a reference for the design and optimization of the radiative heat flux of the external cylindrical receiver.
引文
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[18]Rodriguez-Sanchez M R,Sanchez-Gonzalez A,Marugan-Cruz C,et al.Flow patterns of external solar receivers[J].Solar Energy,2015,122:940-953.
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[21]Mills K C,Su Yuchu,Li Zushu,et al.Equations for the calculation of the thermo-physical properties of stainless steel[J].ISIJ International,2004,44(10):1661-1668.
[22]Yang Shiming,Zhang Zhizeng.An experimental study of natural convection heat transfer from a horizontal cylinder in high Rayleigh number laminar and turbulent regions[J].Begel House Inc.,1994.
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[24]Modest M F.Radiative heat transfer[M].New York:McGraw-Hill,1993.
[25]Duffie J A,Beckman W A,Worek W N.Solar engineering of thermal processes[J].Journal of Solar Energy Engineering,1994,116(1):67-68.
[26]Xu Chao,Wang Zhifeng,Li Xin,et al.Energy and exergy analysis of solar power tower plants[J].Applied Thermal Engineering,2011,31(17-18):3904-3913.
[27]沈维道.工程热力学[M].2版.北京:高等教育出版社,1983.Shen Weidao.Engineering thermodynamics[M].2nd Edition.Beijing:Higher Education Press,1983(in Chinese).
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[29]Garcia P,Ferriere A,Bezian J J.Codes for solar flux calculation dedicated to central receiver system applications:a comparative review[J].Solar Energy,2008,82(3):189-197.
[2]Mostafavi Tehrani S S,Taylor R A,Nithyanandam K,et al.Annual comparative performance and cost analysis of high temperature,sensible thermal energy storage systems integrated with a concentrated solar power plant[J].Solar Energy,2017,153:153-172.
[3]Bradshaw R W,Dawson D B,De la Rosa W,et al.Final test and evaluation results from the solar two project[M].Pacheco J E.Energy Storage.Albuquerque,NM:Sandia National Laboratories,2002.
[4]焦冰琦,张富强,徐志成.基于时序场景的全球联网电力流多期规划模型[J].全球能源互联网,2019,2(1):8-15.Jiao Bingqi,Zhang Fuqiang,Xu Zhicheng.Multi-period planning model of power flow of global energy interconnection based on time series scenarios[J].Journal of Global Energy Interconnection,2019,2(1):8-15(in Chinese).
[5]Zhao Liang,Wang Wei,Zhu Lingzhi,et al.Economic analysis of solar energy development in North Africa[J]Global Energy Interconnection,2018,1(1):53-62.
[6]徐二树,余强,杨志平,等.塔式太阳能热发电腔式吸热器动态仿真模型[J].中国电机工程学报,2010,30(32):115-120.Xu Ershu,Yu Qiang,Yang Zhiping,et al.Solar thermal power tower cavity receiver dynamic simulation model[J].Proceedings of the CSEE,2010,30(32):115-120(in Chinese).
[7]徐二树,胡忠良,翟融融,等.塔式太阳能热电站系统仿真与?分析[J].中国电机工程学报,2014,34(11):1799-1806.Xu Ershu,Hu Zhongliang,Zhai Rongrong,et al.Simulation and exergy analysis of solar thermal Tower plants[J].Proceedings of the CSEE,2014,34(11):1799-1806(in Chinese).
[8]Lata J M,Rodríguez M,de Lara Má.High flux central receivers of molten salts for the new generation of commercial stand-alone solar power plants[J].Journal of Solar Energy Engineering,2008,130(2):021002.
[9]Liao Zhirong,Li Xin,Xu Chao,et al.Allowable flux density on a solar central receiver[J].Renewable Energy,2014,62:747-753.
[10]Liu Bin,Wu Yuting,Ma Chongfang,et al.Turbulent convective heat transfer with molten salt in a circular pipe[J].International Communications in Heat and Mass Transfer,2009,36(9):912-916.
[11]Wu Yuting,Chen Cong,Liu Bin,et al.Investigation on forced convective heat transfer of molten salts in circular tubes[J].International Communications in Heat and Mass Transfer,2012,39(10):1550-1555.
[12]陆建峰,丁静,文玉良,等.聚光太阳能吸热管的吸热传热特性[J].太阳能学报,2010,31(3):328-332.Lu Jianfeng,Ding Jing,Wen Yuliang,et al.Heat absorption and transport characteristics of the concentrated solar receiver pipe[J].Acta Energiae Solaris Sinica,2010,31(3):328-332(in Chinese).
[13]杨敏林,杨晓西,丁静,等.半周加热半周绝热的熔盐吸热管传热特性研究[J].太阳能学报,2009,30(8):1007-1012.Yang Minlin,Yang Xiaoxi,Ding Jing,et al.Heat transfer research on molten salt receiver with semi-circumference heat[J].Acta Energiae Solaris Sinica,2009,30(8):1007-1012(in Chinese).
[14]郑建涛,严俊杰,韩临武,等.多点聚焦的太阳能柱式吸热器能流分布研究[J].中国电机工程学报,2015,35(11):2796-2803.Zheng Jiantao,Yan Junjie,Han Linwu,et al.Analysis of the solar thermal cylinder receiver heat flux distribution under multi-aiming point strategy[J].Proceedings of the CSEE,2015,35(11):2796-2803(in Chinese).
[15]Lippke F.Solar two overall efficiency at reduced receiver outlet temperatures[M].Albuquerque,NM:Sandia National Laboratories,1995.
[16]Siebers D L,Kraabel J S.Estimating convective energy losses from solar central receivers[M].Livermore,CA:Sandia National Laboratories,1984.
[17]Rodríguez-Sánchez M R,Soria-Verdugo A,Almendros-Ibá?ez J A,et al.Thermal design guidelines of solar power towers[J].Applied Thermal Engineering,2014,63(1):428-438.
[18]Rodriguez-Sanchez M R,Sanchez-Gonzalez A,Marugan-Cruz C,et al.Flow patterns of external solar receivers[J].Solar Energy,2015,122:940-953.
[19]Idel?chik I E.Handbook of hydraulic resistance[M].Washington:Hemisphere,1986.
[20]Williams D F,Toth L M,Clarno K T.Assessment of candidate molten salt coolants for the advanced high temperature reactor(AHTR)[R].Oak Ridge,Tennessee:Oak Ridge National Laboratory 2006.
[21]Mills K C,Su Yuchu,Li Zushu,et al.Equations for the calculation of the thermo-physical properties of stainless steel[J].ISIJ International,2004,44(10):1661-1668.
[22]Yang Shiming,Zhang Zhizeng.An experimental study of natural convection heat transfer from a horizontal cylinder in high Rayleigh number laminar and turbulent regions[J].Begel House Inc.,1994.
[23]杨世铭,陶文铨.传热学[M].4版.北京:高等教育出版社,2006.Yang Shiming,Tao Wenquan.Heat transfer[M].4th ed.Beijing:Higher Education Press,2006(in Chinese).
[24]Modest M F.Radiative heat transfer[M].New York:McGraw-Hill,1993.
[25]Duffie J A,Beckman W A,Worek W N.Solar engineering of thermal processes[J].Journal of Solar Energy Engineering,1994,116(1):67-68.
[26]Xu Chao,Wang Zhifeng,Li Xin,et al.Energy and exergy analysis of solar power tower plants[J].Applied Thermal Engineering,2011,31(17-18):3904-3913.
[27]沈维道.工程热力学[M].2版.北京:高等教育出版社,1983.Shen Weidao.Engineering thermodynamics[M].2nd Edition.Beijing:Higher Education Press,1983(in Chinese).
[28]Bejan A,Kearney D W,Kreith F.Second law analysis and synthesis of solar collector systems[J].Journal of Solar Energy Engineering,1981,103(1):23-28.
[29]Garcia P,Ferriere A,Bezian J J.Codes for solar flux calculation dedicated to central receiver system applications:a comparative review[J].Solar Energy,2008,82(3):189-197.