1000MW直接空冷凝汽器流动换热特性研究
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摘要
我国煤炭资源主要集中在北方地区，传统湿冷式凝汽器在北方地区的应用受到限制，直接空冷式凝汽器以其优异的节水性能补充了传统湿冷技术的不足，改变了以水定电的格局，在我国北方地区得到了广泛应用。
蛇形翅片管是直接空冷凝汽器的核心换热元件。对其进行详细的换热流动分析，对直接空冷系统的设计以及运行都具有非常重要的意义。本文应用计算流体力学数值模拟的方法，在不同迎面风速，温度条件以及翅片结构下，对翅片管的流动特性和换热性能进行了深入分析，并得出了翅片管的压力降、阻力系数、换热量、换热系数、出口温度、翅片温度等随迎面风速变化的曲线，提出了努塞尔数N_u与雷诺数R_e之间的无因次关系式，所得到的结果可为我国电站空冷系统的设计和运行提供参考。
建立了单排空冷翅片管和1000MW直接空冷凝汽器单元三维流动换热的物理数学模型，并进行了数值计算，分析了夏季TRL工况下，环境因素对凝汽器单元流动与换热特性的影响规律，以及相邻单元之间的相互影响。重点研究了在最不利条件，即夏季高温且有自然大风条件下，空冷凝汽器边缘迎风单元流动换热差的问题，并给出了解决的措施，提出一种新型导流布置方式。分析结果表明单纯改变裙板高度对缓解大风影响效果有限；新型导流布置方式有效地改善了最不利条件下空冷单元的运行情况。
The application of traditional wet-cooled condensers are limited and directair-cooled condensers(DACC) are widely and increasingly used in northernChina, where the coal mine mainly distributes upon, but water is short anddominates the price of electricity power.
The finned-tube is the key element of heat transfer of DACC. R_esearches onthe flow and heat transfer performance of DACC is of great importance in thedesign and operation of DACC. Under different windward velocity, the flow andheat transfer performances of the finned-tube have been calculated and analyzedbased on CFD(Computational Fluid Mechanics). The relationships betweenpressure drop, fractional coefficient, heat exchange capacity, convectioncoefficient, outlet temperature, finned-tube temperature and windward velocity,and also the dimensionless relationship between N_usselt number and R_enoldsnumber are presented. The results can provide a theoretical basis for the optimaldesign of DACC.
Physical and mathematical models were established for the finned-tube andthe DACC’s unit, and upon which the rules of flow and heat transferperformances affected by environment under the TRL operating mode in summer ,and the influence of the adjoining units were studied. The worst operatingcondition of DACC that is the gale in summer was emphasized, and under thiscondition the problem of bad heat transfer performance of the units on the edgeof DACC was analyzed. Methods were given and also a new type of guide flowdevice was created to improve the problem. The results of the numericalsimulation show that the length of apron has limited benefit to the gale condition,but the new type of guide flow device improves the problem well.
蛇形翅片管是直接空冷凝汽器的核心换热元件。对其进行详细的换热流动分析，对直接空冷系统的设计以及运行都具有非常重要的意义。本文应用计算流体力学数值模拟的方法，在不同迎面风速，温度条件以及翅片结构下，对翅片管的流动特性和换热性能进行了深入分析，并得出了翅片管的压力降、阻力系数、换热量、换热系数、出口温度、翅片温度等随迎面风速变化的曲线，提出了努塞尔数N_u与雷诺数R_e之间的无因次关系式，所得到的结果可为我国电站空冷系统的设计和运行提供参考。
建立了单排空冷翅片管和1000MW直接空冷凝汽器单元三维流动换热的物理数学模型，并进行了数值计算，分析了夏季TRL工况下，环境因素对凝汽器单元流动与换热特性的影响规律，以及相邻单元之间的相互影响。重点研究了在最不利条件，即夏季高温且有自然大风条件下，空冷凝汽器边缘迎风单元流动换热差的问题，并给出了解决的措施，提出一种新型导流布置方式。分析结果表明单纯改变裙板高度对缓解大风影响效果有限；新型导流布置方式有效地改善了最不利条件下空冷单元的运行情况。
The application of traditional wet-cooled condensers are limited and directair-cooled condensers(DACC) are widely and increasingly used in northernChina, where the coal mine mainly distributes upon, but water is short anddominates the price of electricity power.
The finned-tube is the key element of heat transfer of DACC. R_esearches onthe flow and heat transfer performance of DACC is of great importance in thedesign and operation of DACC. Under different windward velocity, the flow andheat transfer performances of the finned-tube have been calculated and analyzedbased on CFD(Computational Fluid Mechanics). The relationships betweenpressure drop, fractional coefficient, heat exchange capacity, convectioncoefficient, outlet temperature, finned-tube temperature and windward velocity,and also the dimensionless relationship between N_usselt number and R_enoldsnumber are presented. The results can provide a theoretical basis for the optimaldesign of DACC.
Physical and mathematical models were established for the finned-tube andthe DACC’s unit, and upon which the rules of flow and heat transferperformances affected by environment under the TRL operating mode in summer ,and the influence of the adjoining units were studied. The worst operatingcondition of DACC that is the gale in summer was emphasized, and under thiscondition the problem of bad heat transfer performance of the units on the edgeof DACC was analyzed. Methods were given and also a new type of guide flowdevice was created to improve the problem. The results of the numericalsimulation show that the length of apron has limited benefit to the gale condition,but the new type of guide flow device improves the problem well.
引文
1伍小林.我国火力发电厂空气冷却技术的发展现状[J].国际电力，2005，9(l):15-18
2马义伟.发电厂空冷技术的现状与进展[J].电力设备，2006，7(3):5-7
3王佩璋.单机大型空冷电厂的节水能力与废水零排放.电站辅机，2004，88(1):23-26
4傅松，王福禄.当前空冷电站存在的问题及国外的先进经验[J].电力情报，1995，(4):8-11
5丁尔谋.直接空冷技术的发展和应用[J].2006，21(2):186-189
6王佩璋.空冷技术在火力发电上的应用与发展[J].电站辅机,2006，96(3):32-38
7 Kays.W.M,London.A.L.Compact Heat Exchanger.3rd ed.NY:MacGraw-Hill Book Company.1984
8 A.Joardar，A.M.Jacobi.Heat transfer enhancement by winglet-type vortexgenerator arrays in compact plain-fin-and-tube heat exchangers[J].International Journal of Refrigeration.2007,04(11):l-11
9张鹏，史佑吉，高伟桐，胡三季.进风角度对钢制椭圆翅片管散热器热力阻力特性的影响[J].热力发电.1997,(l):19-21
10王厚华，罗庆，苏华，范亚明.大直径圆孔翅片管的传热与流阻性能实验研究[J].制冷学报.2002,(2):25-29
11康海军，李惠珍.平直翅片管换热器传热与阻力特性的实验研究[J].西安交通大学学报.1994,28(1):91一98
12屠珊，杨冬，黄锦涛，陈听宽，罗毓珊.椭圆翅片管空冷器流动传热特性的研究[J].热能动力工程.2000，15(89):455一458
13 R.S.Matos，J.VC.Vargas，T.A.laursen，A.Bejan.Optimally staggeredfinned circular and elliptic tubes in forced convection [J].InternationalJournal of Heat and Mass Transfer.2004,47(6):1347一1359
14 Rieardo Romero-Mende，Mihir Sen，K.T.Ya，Rodney McClain.Effect offin spacing on convection in a plate fin and tube heat exchanger[J].Intemational Joumal of Heat and MassTransfer.2000,43(l):39-51
15许伟.几种典型翅片传热及阻力特性的数值研究与分析〔D].清华大学硕士论文.2005
16胡汉波.直接空冷式凝汽器翅片散热器流动传热性能及单元流场特性研究[D].重庆大学硕士论文,2006
17曾时明.电站直接空冷式翅片管换热和流动规律及空冷单元流场特性数值研究[D].北京交通大学,2007
18 Haci Mehmet Sahin，Ali Riza Dal，Esref Baysal. 3-D Numerical studyon the Correlation between variable inelined fin angles and thermalbehavior in plate fin-tube heat exehanger[J].Applied ThermalEngineering.2007,27(11):1806-1816
19 Yang LJ, DuXZ, YangYP,etal.Influences of wind on flow and heat transferof cooling air in direct air-cooled condensers[C]. The EighteenthInternational Symposium on Transport Phenomena,27- 30,Aug ,2007 ,Daejeon, Korea.
20 K.Duvenhage, D.G.Koger.The influence of wind on the performance offorced draught air-cooled heat exchangers[J].Journal of Wind Engineeringand Industrial Aerodynamics.1996,62(l):259-277
21 van Staden，MartinP，Pretorius Leon.Numerical modeling of the effectsof ambient conditions on large power station air cooled steamcondensers.Ameriean Soeiety of Mechanieal Engineers，FluidsEngineering Division (Publication)FED，v221,Industrial andEnvironmental Applications of Fluid Mechanies,1995,145-150
22 J.R.Bredell，D.G.Kroger，G.D.Thiart.Numerical investigation of fanperformance in a forced draft air-cooled steam condenser[J].APPliedThermal Engineering.2006,26(8):846-552
23 P.J.Hotehkiss，C.J.Meyer，T.W.vonBaekstrom.Numerical investigationinto the effect of cross-flow on the Performance of axial flow fans inforced draught air-eooled[J].APPlied Thermal Engineering.2006,26(2):200-208
24赵文升，王松岭，汤世凯.基于CFD软件的直接空冷系统热风回流现象的分析[J].汽轮机技术，2007,49(5):346-345
25赵文升，王松龄，高月芬，等.直接空冷系统中热风回流现象的数值模拟和分析[J].动力工程.2007,27(4):487-491
26周兰欣，杨靖，杨祥.600Mw直接空冷机组变工况特性的研究[J].动力工程.2007,27(2):165-168，217
27 Zhifu Gu，HuiLi Chen，etal.Wind tunnel simulationon recirculation ofair cooled condenser sofa Power Plant[J].Journal of Wind Engineering andIndustrial Aerodynamics.2005,93(6):509-520
28 Zhifu Gu，Xuerei Chen，WilliamLubitz，etal.Wind tunnel simulation ofExhaust recireulation in an air-cooling system at a large Powerplant[J].International journal of Thermal Scienees.2007，46(3):308-317
29顾志福，陈学锐，李燕，等.大型电厂直接冷系统风洞效应风洞模拟[J].力学学报，2005,37(5):558-563
30 C.J.Meyer.Numerical investigation of the effect of inlet flow distortiorsonforced draught air-cooled heat exehanger Performance[J]. APPlied ThermalEngineering 2005,25(11):1634-1649
31 C.J.Meyer，D.G.Kroger.Numerical investigation of the effect of fanPerformance on forced draught air-cooled heat exehanger Plenume hamberaerodynamic behaviour[J]Applied Thermal Engineering 2004,24(2):359-37132杨立军，周健，杜小泽，等.扁平管外蛇形翅片空间的流动换热性能数值模拟[J].工程热物理学报，2007,28(1):122-124
33胡汉波，李隆键.直接空冷凝汽器三维流场特性的数值分析[J].动力工程2007.8 592-595
34白中华.直接空冷机组空冷岛外部流场的数值研究[D].华北电力大学硕士学位论文.2007.12
35申微波.直接空冷器空气侧传热和流动的数值模拟[D].华中科技大学硕士论文.2008.6
36张凯峰.电站直接空冷系统翅片管流动与换热性能数值研究[D].华北电力大学硕士论文,2008年
37过增元,黄素逸.场协同原理与强化传热新技术[M].北京:中国电力出版社,2004
38陶文铨.数值传热学[M].西安:西安交通大学出版社,2001
39 Johannes C. Kloppers,Detlev G. Kroger.Cooling tower performanceevaluation: merkel, poppe, ande -NTU methods of Analysis [J]. Journal ofEngineering for Gas Turbines and Power.2005,127(1):1-7
40 Meyer.C.J,Kroger.D.G.Air-cooled heat exchanger inlet flow losses[J].Applied Thermal Engineering,2001,21(7):771-786．
41杨立军，杜小泽，杨勇平，等．火电站直接空冷凝汽器性能考核评价方法[J]．中国电机工程学报，2008,28(14):32-36．
42杨立军，杜小泽，金衍胜，等．火电站直接空冷凝汽器传热系数实验关联式[J].中国电机工程学报，2007,27(2):59-63．
43 A. E. Conradie ,D. G. Kroger. Perfomance evaluation of dry-coolingsystems for power plant applicatiions[J]. Applied Thermal Engineering,1995,16(5):219-232
44 F.W. Yu , K.T. Chan. Optimizing condenser fan control for air-cooledcentrifugal chillers[J]. International Journal of Thermal Sciences. 2008,47(8):942–953
45 Chi-Chuan Wang, Kuan-Yu Chi.Heat transfer and friction characteristics ofplain fin-and-tube heat exchangers, part I: new experimental data[J].International Journal of Heat and Mass Transfer, 2000,43 (10) 2681-2691
46 Paulo A.B. de Sampaio, Jose′L.H. Faccini, Jian Su. Modelling of stratifiedgas–liquid two-phase flow in horizontal circular pipes[J]. InternationalJournal of Heat and Mass Transfer ,2008,51 (12) 2752–2761
47周兰欣，李建波，李卫华,等.直接空机组凝汽器加装下挡风墙的数值模拟[J].动力工程,2008,28(5):744-747
2马义伟.发电厂空冷技术的现状与进展[J].电力设备，2006，7(3):5-7
3王佩璋.单机大型空冷电厂的节水能力与废水零排放.电站辅机，2004，88(1):23-26
4傅松，王福禄.当前空冷电站存在的问题及国外的先进经验[J].电力情报，1995，(4):8-11
5丁尔谋.直接空冷技术的发展和应用[J].2006，21(2):186-189
6王佩璋.空冷技术在火力发电上的应用与发展[J].电站辅机,2006，96(3):32-38
7 Kays.W.M,London.A.L.Compact Heat Exchanger.3rd ed.NY:MacGraw-Hill Book Company.1984
8 A.Joardar，A.M.Jacobi.Heat transfer enhancement by winglet-type vortexgenerator arrays in compact plain-fin-and-tube heat exchangers[J].International Journal of Refrigeration.2007,04(11):l-11
9张鹏，史佑吉，高伟桐，胡三季.进风角度对钢制椭圆翅片管散热器热力阻力特性的影响[J].热力发电.1997,(l):19-21
10王厚华，罗庆，苏华，范亚明.大直径圆孔翅片管的传热与流阻性能实验研究[J].制冷学报.2002,(2):25-29
11康海军，李惠珍.平直翅片管换热器传热与阻力特性的实验研究[J].西安交通大学学报.1994,28(1):91一98
12屠珊，杨冬，黄锦涛，陈听宽，罗毓珊.椭圆翅片管空冷器流动传热特性的研究[J].热能动力工程.2000，15(89):455一458
13 R.S.Matos，J.VC.Vargas，T.A.laursen，A.Bejan.Optimally staggeredfinned circular and elliptic tubes in forced convection [J].InternationalJournal of Heat and Mass Transfer.2004,47(6):1347一1359
14 Rieardo Romero-Mende，Mihir Sen，K.T.Ya，Rodney McClain.Effect offin spacing on convection in a plate fin and tube heat exchanger[J].Intemational Joumal of Heat and MassTransfer.2000,43(l):39-51
15许伟.几种典型翅片传热及阻力特性的数值研究与分析〔D].清华大学硕士论文.2005
16胡汉波.直接空冷式凝汽器翅片散热器流动传热性能及单元流场特性研究[D].重庆大学硕士论文,2006
17曾时明.电站直接空冷式翅片管换热和流动规律及空冷单元流场特性数值研究[D].北京交通大学,2007
18 Haci Mehmet Sahin，Ali Riza Dal，Esref Baysal. 3-D Numerical studyon the Correlation between variable inelined fin angles and thermalbehavior in plate fin-tube heat exehanger[J].Applied ThermalEngineering.2007,27(11):1806-1816
19 Yang LJ, DuXZ, YangYP,etal.Influences of wind on flow and heat transferof cooling air in direct air-cooled condensers[C]. The EighteenthInternational Symposium on Transport Phenomena,27- 30,Aug ,2007 ,Daejeon, Korea.
20 K.Duvenhage, D.G.Koger.The influence of wind on the performance offorced draught air-cooled heat exchangers[J].Journal of Wind Engineeringand Industrial Aerodynamics.1996,62(l):259-277
21 van Staden，MartinP，Pretorius Leon.Numerical modeling of the effectsof ambient conditions on large power station air cooled steamcondensers.Ameriean Soeiety of Mechanieal Engineers，FluidsEngineering Division (Publication)FED，v221,Industrial andEnvironmental Applications of Fluid Mechanies,1995,145-150
22 J.R.Bredell，D.G.Kroger，G.D.Thiart.Numerical investigation of fanperformance in a forced draft air-cooled steam condenser[J].APPliedThermal Engineering.2006,26(8):846-552
23 P.J.Hotehkiss，C.J.Meyer，T.W.vonBaekstrom.Numerical investigationinto the effect of cross-flow on the Performance of axial flow fans inforced draught air-eooled[J].APPlied Thermal Engineering.2006,26(2):200-208
24赵文升，王松岭，汤世凯.基于CFD软件的直接空冷系统热风回流现象的分析[J].汽轮机技术，2007,49(5):346-345
25赵文升，王松龄，高月芬，等.直接空冷系统中热风回流现象的数值模拟和分析[J].动力工程.2007,27(4):487-491
26周兰欣，杨靖，杨祥.600Mw直接空冷机组变工况特性的研究[J].动力工程.2007,27(2):165-168，217
27 Zhifu Gu，HuiLi Chen，etal.Wind tunnel simulationon recirculation ofair cooled condenser sofa Power Plant[J].Journal of Wind Engineering andIndustrial Aerodynamics.2005,93(6):509-520
28 Zhifu Gu，Xuerei Chen，WilliamLubitz，etal.Wind tunnel simulation ofExhaust recireulation in an air-cooling system at a large Powerplant[J].International journal of Thermal Scienees.2007，46(3):308-317
29顾志福，陈学锐，李燕，等.大型电厂直接冷系统风洞效应风洞模拟[J].力学学报，2005,37(5):558-563
30 C.J.Meyer.Numerical investigation of the effect of inlet flow distortiorsonforced draught air-cooled heat exehanger Performance[J]. APPlied ThermalEngineering 2005,25(11):1634-1649
31 C.J.Meyer，D.G.Kroger.Numerical investigation of the effect of fanPerformance on forced draught air-cooled heat exehanger Plenume hamberaerodynamic behaviour[J]Applied Thermal Engineering 2004,24(2):359-37132杨立军，周健，杜小泽，等.扁平管外蛇形翅片空间的流动换热性能数值模拟[J].工程热物理学报，2007,28(1):122-124
33胡汉波，李隆键.直接空冷凝汽器三维流场特性的数值分析[J].动力工程2007.8 592-595
34白中华.直接空冷机组空冷岛外部流场的数值研究[D].华北电力大学硕士学位论文.2007.12
35申微波.直接空冷器空气侧传热和流动的数值模拟[D].华中科技大学硕士论文.2008.6
36张凯峰.电站直接空冷系统翅片管流动与换热性能数值研究[D].华北电力大学硕士论文,2008年
37过增元,黄素逸.场协同原理与强化传热新技术[M].北京:中国电力出版社,2004
38陶文铨.数值传热学[M].西安:西安交通大学出版社,2001
39 Johannes C. Kloppers,Detlev G. Kroger.Cooling tower performanceevaluation: merkel, poppe, ande -NTU methods of Analysis [J]. Journal ofEngineering for Gas Turbines and Power.2005,127(1):1-7
40 Meyer.C.J,Kroger.D.G.Air-cooled heat exchanger inlet flow losses[J].Applied Thermal Engineering,2001,21(7):771-786．
41杨立军，杜小泽，杨勇平，等．火电站直接空冷凝汽器性能考核评价方法[J]．中国电机工程学报，2008,28(14):32-36．
42杨立军，杜小泽，金衍胜，等．火电站直接空冷凝汽器传热系数实验关联式[J].中国电机工程学报，2007,27(2):59-63．
43 A. E. Conradie ,D. G. Kroger. Perfomance evaluation of dry-coolingsystems for power plant applicatiions[J]. Applied Thermal Engineering,1995,16(5):219-232
44 F.W. Yu , K.T. Chan. Optimizing condenser fan control for air-cooledcentrifugal chillers[J]. International Journal of Thermal Sciences. 2008,47(8):942–953
45 Chi-Chuan Wang, Kuan-Yu Chi.Heat transfer and friction characteristics ofplain fin-and-tube heat exchangers, part I: new experimental data[J].International Journal of Heat and Mass Transfer, 2000,43 (10) 2681-2691
46 Paulo A.B. de Sampaio, Jose′L.H. Faccini, Jian Su. Modelling of stratifiedgas–liquid two-phase flow in horizontal circular pipes[J]. InternationalJournal of Heat and Mass Transfer ,2008,51 (12) 2752–2761
47周兰欣，李建波，李卫华,等.直接空机组凝汽器加装下挡风墙的数值模拟[J].动力工程,2008,28(5):744-747