螺旋外肋管换热器壳侧流体流动与换热特性数值研究

Numerical Investigation on Heat Transfer and Fluid Flow Properties in Shell-Side of Heat Exchanger with Spiral Finned Tubes

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.