螺旋外肋管换热器壳侧流体流动与换热特性数值研究
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摘要
利用CFD技术,研究了螺距及肋高对螺旋外肋管换热器壳程流体流动和换热性能的影响。建立了壳程周期性单元流道模型并进行数值计算,详细分析了不同螺距、肋高对壳程流体流动及换热的影响。结果表明,适当地减小螺距可以有效地强化管壁对流换热效果,同时伴随着摩擦阻力系数的增大,但综合换热性能更强。在高雷诺数区域,随肋高的增大,螺旋外肋管的换热性能随肋高的增加比较明显,而摩擦阻力系数的变化与肋高变化的程度大致相同。速度场和温度场的平均协同角随螺距的减小而减小,协同程度增强。提出了螺旋外肋管换热器壳程换热及阻力性能公式供相关工程设计参考,并对外肋管换热器壳程综合强化性能做出了评价。
A numerical study was performed to investigate the effect of fin pitch and fin height on the fluid flow and heat transfer in shell side of spiral finned tubes exchanger with CFD technology. Unit duct model in shell side was built. The fin pitch is from 10mm to 25mm and the fin height is from 0.5mm to 1.2mm. The Reynolds number is from 10,000 to 15,000. It is observed that by decreasing the fin pitch,the heat transfer on the tube wall is enhanced effectively. Meanwhile the frictional resistance coefficients increase and the comprehensive heat transfer performance is enhanced. With the increase of fin height,the heat transfer characteristic increases obviously in the high Reynolds number region,though the change of frictional resistance coefficients keeps the same with the increment of fin height. The average field-synergy angles between velocity field and temperature field decrease with fin pitch decreasing. Based on the field-synergy theory,the synergy degree between heat transfer and fluid flow is enhanced. The correlations of heat transfer characteristic and fluid flow resistance characteristic are introduced,which will benefit engineering applications. At last the comprehensive enhancement performance of shell-side heat exchanger with spiral finned tubes was evaluated in the paper.
A numerical study was performed to investigate the effect of fin pitch and fin height on the fluid flow and heat transfer in shell side of spiral finned tubes exchanger with CFD technology. Unit duct model in shell side was built. The fin pitch is from 10mm to 25mm and the fin height is from 0.5mm to 1.2mm. The Reynolds number is from 10,000 to 15,000. It is observed that by decreasing the fin pitch,the heat transfer on the tube wall is enhanced effectively. Meanwhile the frictional resistance coefficients increase and the comprehensive heat transfer performance is enhanced. With the increase of fin height,the heat transfer characteristic increases obviously in the high Reynolds number region,though the change of frictional resistance coefficients keeps the same with the increment of fin height. The average field-synergy angles between velocity field and temperature field decrease with fin pitch decreasing. Based on the field-synergy theory,the synergy degree between heat transfer and fluid flow is enhanced. The correlations of heat transfer characteristic and fluid flow resistance characteristic are introduced,which will benefit engineering applications. At last the comprehensive enhancement performance of shell-side heat exchanger with spiral finned tubes was evaluated in the paper.
引文
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[3]何法江,曹伟武,匡江红.螺旋翅片管束传热和阻力特性的试验研究[J].动力工程,2005,29(5):460-464.(He Fa-jiang,Cao Wei-wu,Kuang Jiang-hong.Heat transfer and resistance characteristics of spiral finned tube bundles[J].Journal of Power Engineering,2005,29(5):460-464.)
[4]王为术,徐维晖,陈听宽.内螺纹管内流动传热特性研究进展[J].华北水利水电学院学报,2011,32(4):81-87.(Wang Wei-shu,Xu Wei-hui,Chen Ting-kuan.Research progress on characteristics of flow and heat transfer in internally ribbed tubes[J].Journal of North China Institute of Water Conservancy and Hydroelectric Power,2011,32(4):81-87.)
[5]衣秋杰,冯晓燕,朱长耀.单头螺纹槽管管内强化传热机理分析及优化设计[J].化工进展,2006(25):329-333.(Yi Qiu-jie,Feng Xiao-yan,Zhu Chang-yao.Theoretical analysis and optimization design of heat transfer enhancement in single spirally indented tubes[J].Chemical Industry and Engineering Progress,2006(25):329-333.)
[6]Weierman C.Pressure drop data for heavy-duty finned tubes[J].Chemical Engineering Progress,1977,73(2):69-72.
[7]Kawaguchi K,Okui K,Kashi T.Heat transfer and pressure drop characteristics of finned tube banks in forced convenction(comparison of the heat transfer characteristics between spiral fin and serrated fin)[J].Heat Transfer-Asian Research,2005,34(2):120-133.
[8]Garimella S,Christensen R N.Heat transfer and pressure drop characteristics of spirally fluted annuli:PartⅡ-heat transfer[J].Heat Transfer,1995,117(1):61-68.
[9]吴金星,魏新利,董其伍.杆支撑换热器壳程的单元流道模型及流场分布[J].化工进展,2007,26(1):69-72.(Wu Jin-xing,Wei Xin-li,Dong Qi-wu.Unit duct model and flow field distribution in shell side of rod baffle heat exchanger[J].Chemical Industry and Engineering Progress,2007,26(1):69-72.)
[10]王玉,于斐,翟守信.翅片管及其在管壳式换热器的使用[J].管道技术与设备,2000(3):22-24.(Wang Yu,Yu Fei,Zhai Shou-xin.Finned tubes and their application in the tubular heat exchanger[J].Tube Technology and Equipment,2000(3):22-24.)