涡发生器与螺旋片强化不同曲率的壳侧传热

为考察涡发生器与螺旋片对不同曲率的套管式换热器壳侧的传热强化效果,在不同中径的壳侧安装了相同密度的螺旋片和三角翼型涡发生器。以空气为介质,在Re=680～16000范围内,采用实验和数值模拟方法研究了壳侧的传热和阻力特性,考察了不同曲率下复合强化的壳侧的综合性能,分析了传热强化机理。结果表明,曲率越大,壳侧传热系数越高,摩擦因数越大。对曲率分别为0.131、0.321和0.440的3种换热器壳侧,涡发生器将其传热系数平均提高了31.52%、20.83%和18.33%。小曲率和复合强化的壳侧综合性能更好。涡发生器改变了换热器壳侧的流场结构,提高了速度场和温度场之间的协同性,从而提高了换热器壳侧的传热效果。

Heat transfer enhancement with helical fins and vortex generators on shells at different curvatures

To examine the heat transfer performance of compound enhancement with helical fins and vortex generators for the shell of double-pipe heat exchangers at different curvatures,helical fins and delta-winglet-pair vortex generators are installed on the shell side with different middle diameters at the same pitch.Heat transfer and pressure drop characteristics on the shell side are investigated experimentally and numerically at Re=680-16000 with air as working fluid.The comprehensive performance on the shell side is enhanced and the enhancement mechanism is analyzed.The results show that larger curvature of the shell leads higher heat transfer coefficient and friction factor.For curvatures of 0.131,0.321 and 0.440,heat transfer coefficient is increased by 31.52%,20.83% and 18.33%,respectively,with vortex generators. Vortex generators can change the fluid flow structure and improve the synergy of velocity field and temperature field,so the heat transfer on the shell side is improved.