整体型螺旋翅片管束流动换热特性数值研究

Numerical study on flow and heat transfer characteristics of integral spiral finned tube bundles

整体型螺旋翅片管相比传统类型翅片管(高频焊螺旋翅片管和H型翅片管)具有显著优势,在锅炉低压省煤器上具有广阔的应用前景,但其流动换热特性尚不明晰。本文采用数值模拟的方法研究了翅片高度、翅片节距、横向管距和纵向管距对整体型螺旋翅片管束传热和阻力特性的影响。综合考虑流动性能、对流换热性能和固体导热性能,提出以η0j/f^(1/3)表征翅片管综合性能。研究结果表明:Realizable k-ε模型的预测适用性最佳;横向管距减小,综合性能显著提升;翅片节距对综合性能影响不大;相对翅片高度hf/d0=0.32或相对纵向管距SL/d0=2.89时,综合性能最优。同时,拟合了错列整体型螺旋翅片管束(纵向4排)Eu和Nu的关联式,可为工程应用提供参考。

Integral spiral finned tubes have significant advantages versus conventional finned tubes like high frequency resistance welded spiral finned tubes and H-type finned tubes,and have broad application prospect in low pressure economizer.However,the thermal-hydraulic characteristics of integral spiral finned tube bundles are still not clear.The effects of fin height,fin pitch,transversal tube spacing and longitudinal tube spacing on resistance and heat transfer characteristics of integral spiral finned tube bundles are studied numerically in this paper.The overall thermal-hydraulic performance evaluation criteria η0j/f^(1/3) considering fluid flow,convective heat transfer and solid heat conduction characteristics is proposed.The results indicate that,the predictive applicability of the Realizable k-ε model is the best.The overall thermal-hydraulic performance increases significantly with reducing transversal tube spacing while it remains unchanged with the change of fin pitch.The best overall thermal-hydraulic performance will be obtained when the relative fin height hf/d0 or relative longitudinal tube spacing SL/d0 are 0.32 or 2.89 respectively.Moreover,correlations of the Euler number and Nusselt number for 4-row staggered integral spiral tube bundles are presented,which may be useful for engineering application.