翅片螺距对折齿型螺旋翅片管束性能的影响

为了提高平齿型翅片管的强化传热效果,通过改变其锯齿的扭转方向和偏折角度得到了折齿型螺旋翅片管。利用数值模拟和模化试验相结合的方法对基管外径分别为38 mm和51 mm的折齿型螺旋翅片管束进行研究,得到了翅片螺距对折齿型螺旋翅片管束的换热与阻力性能的影响规律和最优翅片螺距。结果表明:翅片螺距P_f在3.63~8.47 mm范围内,空气侧Nusselt数Nu随P_f增大呈先递增后递减的趋势;当P_f大于6.35 mm时,翅片螺距增大对Nu的影响相对已不明显;空气侧Euler数Eu随P_f增大而减小。对于基管外径分别为38 mm和51 mm的折齿型螺旋翅片管束,P_f为6.35 mm时其性能指标Nu·f ^-1/3均最大,因此P_f=6.35 mm是最优翅片螺距。

Effects of fin pitch on heat transfer and flow resistance of twisted-serrated spiral finned tube banks

In order to improve the heat transfer enhancement of serrated spiral-finned-tube, twisted-serrated spiral finned tube was fabricated by changing the deflection angle and the twisted direction of serration. Twisted-serrated spiral finned tube banks with the diameters of 38 mm and 51 mm were researched by numerical simulation combined with modeling experiments. The influence of fin pitch on heat transfer and resistance characteristics of twisted-serrated spiral finned tube was obtained. The results showed that Nu at air-side increased firstly and then decreased with the increase of fin pitch from 3.63-8.47 mm. The effects of fin pitch on Nu at air-side was weaker when the fin pitch was larger than 6.35 mm. Eu at air-side decreased with increasing fin pitch. For twisted-serrated spiral finned tube banks with the diameters of 38 mm and 51 mm, comprehensive performance index Nu·f^-1/3 was the maximum when the fin pitch is 6.35 mm. Thus, P_f =6.35 mm was the optimum fin pitch within the range of 3.63-8.47 mm.