新型翅片管束提高自然通风直接空冷系统效率
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摘要
自然通风直接空冷系统凝汽器单元"Λ"型布局和传统翅片结构使得冷却空气流过翅片管束时发生严重转向,从而显著影响空冷凝汽器的流动传热性能。提出了一种新型翅片管束,其翅片通道与基管椭圆长轴方向呈一定夹角,使翅片通道方向与塔浮升力方向平行。通过CFD数值模拟和实验验证,获得了采用新型倾斜翅片管束的自然通风空冷凝汽器的空气流场和温度场,计算得到了不同环境风速下空冷凝汽器总换热量的变化规律,并与现有翅片管束的空冷凝汽器性能进行了对比。研究结果表明,采用倾斜翅片空冷凝汽器可以显著改善自然通风直接空冷系统热力性能,降低机组背压,提高空冷机组运行的经济性。
Due to the"Λ"type layout of air-cooled condenser cell for natural draft direct dry cooling system and traditional fin arrangement on the finned tube bundles,the cooling air turns its direction severely when passing through the fin tubes,thus the thermo-flow performances of air-cooled condenser are likely to become deteriorated. A new configuration of fin tubes,in which the channel of fin and elliptic axis direction of base tube form a certain angle that the channel of fin is parallel to the direction of tower buoyancy,is proposed in this paper. By CFD numerical simulation and experimental validation,the flow and temperature fields of natural draft air-cooled condenser are obtained for the new oblique finned tube,and the total heat rejection is calculated at various wind speeds,then they are compared with the current finned tube bundles of air-cooled condenser. The results show that the thermal-flow performances of air-cooled condenser for natural draft direct dry cooling system with oblique fin get improved significantly and the turbine back pressure is reduced,which can contribute to the economical operation of dry cooling system correspondingly.
Due to the"Λ"type layout of air-cooled condenser cell for natural draft direct dry cooling system and traditional fin arrangement on the finned tube bundles,the cooling air turns its direction severely when passing through the fin tubes,thus the thermo-flow performances of air-cooled condenser are likely to become deteriorated. A new configuration of fin tubes,in which the channel of fin and elliptic axis direction of base tube form a certain angle that the channel of fin is parallel to the direction of tower buoyancy,is proposed in this paper. By CFD numerical simulation and experimental validation,the flow and temperature fields of natural draft air-cooled condenser are obtained for the new oblique finned tube,and the total heat rejection is calculated at various wind speeds,then they are compared with the current finned tube bundles of air-cooled condenser. The results show that the thermal-flow performances of air-cooled condenser for natural draft direct dry cooling system with oblique fin get improved significantly and the turbine back pressure is reduced,which can contribute to the economical operation of dry cooling system correspondingly.
引文
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[9]杨立军,贾思宁,卜永东,等.电站间冷系统空冷散热器翅片管束流动传热性能的数值研究[J].中国电机工程学报,2012,32:50-57.
[10] Yang L J,Du X Z,Yang Y P. Space Characteristics of the Thermal Performance for Air-cooled Condensers at Ambient Winds[J]. International Journal of Heat and Mass Transfer,2011,54:3109-3119.
[2] Kong Y,Wang W,Yang L,et al. Thermo-flow Performances of Natural Draft Direct Dry Cooling System at Ambient winds[J]. International Journal of Heat&Mass Transfer,2018,116:173-184.
[3]周兰欣,王智刚,李卫华.空冷凝汽器U型翅片管换热特性研究[J].汽轮机技术,2009,51(6):441-444.
[4] Kong Y Q,Yang L J,Du X Z,et al. Air-side flow and Heat Transfer Characteristics of Flat and Slotted Finned Tube Bundles with Various Tube Pitches[J]. International Journal of Heat and Mass Transfer,2016,99:357-371.
[5] Tian L,He Y,Tao Y,et al. A Comparative Study on the Air-side Performance of Wavy Fin-and-tube Heat Exchanger with Punched Delta Winglets in Staggered and In-line Arrangements[J]. International Journal of Thermal Sciences,2009,48:1765-1776.
[6] Zhao Y B,Sun F,Li Y,et al. Yang. Numerical Study on the Cooling Performance of Natural Draft Dry Cooling Tower with Vertical delta Radiators Under Constant Heat Load[J]. Applied Energy,2015,149:225-237.
[7] Zhao Y B,Long G,Sun F,et al. Zhang. Numerical Study on the Cooling Performance of Dry Cooling Tower with Vertical Two-pass Column Radiators Under Crosswind[J]. Applied Thermal Engineering,2015,75:1106-1117.
[8] Kong Y Q,Wang W J,Huang X W,et al. Direct Dry Cooling System Through Hybrid Ventilation for Improving Cooling Efficiency in Power Plants[J]. Applied Thermal Engineering,2017,119:254-268.
[9]杨立军,贾思宁,卜永东,等.电站间冷系统空冷散热器翅片管束流动传热性能的数值研究[J].中国电机工程学报,2012,32:50-57.
[10] Yang L J,Du X Z,Yang Y P. Space Characteristics of the Thermal Performance for Air-cooled Condensers at Ambient Winds[J]. International Journal of Heat and Mass Transfer,2011,54:3109-3119.