摘要
为了研究扭曲扁管在冷凝器中的运行特性,采用实验研究方法对扭曲扁管与普通直管的传热、流动阻力和污垢特性进行了研究。实验采用φ25×2.5的普通直管和由同种直管制成的扭曲扁管,扭曲扁管导程分别为120mm、150mm、180mm。实验表明,导程减小,阻力系数增大,扭曲扁管流动阻力系数约为直管的1.75～2倍。扭曲扁管的传热系数在洁净状态下约为直管1.2～2.3倍,在污垢状态下,约为直管1.8～2.1倍。随着Re增大,污垢热阻减小,但螺旋扁管的减小速度比直管更大,在Re=3000情况下螺旋扁管的污垢热阻与直管相近,当Re>6000时,螺旋扁管污垢热阻约为光管的0.16～0.42倍。通过分析,得出了污垢状态下实验扭曲扁管的最佳工作区。
The experiments on heat transfer, flow resistance, and fouling characteristics of normal tubes or twisted tubes in a condenser were conducted. The normal tube size was φ25×2.5. The twisted tubes were made of the normal tube with the same size, and the screw pitch was 120mm, 150mm, and 180mm, respectively. The results show that the flow resistance coefficient of the twisted tube is about 1.75-2 times that of the normal tube, and it increases with the decrease of screw pitch. The heat transfer coefficient of the twisted tube is about 1.2-2.3 times that of the normal tube at the clean condition and 1.8-2.1 times at the fouling condition. The heat resistance of fouling decreases when Re increases, but it decreases much more for the twisted tube. When Re=3000, the values of fouling heat resistance for both tubes are very close. As Re〉6000, the fouling heat resistance of the twisted tube is about 0.16-0.42 times that of the normal tube. On the basis of the experimental results, the optimum range of Re for the fouling twisted tube was obtained.
出处
《制冷学报》
CAS
CSCD
北大核心
2007年第6期47-50,共4页
Journal of Refrigeration
关键词
工程热物理
强化传热
实验研究
扭曲扁管
冷凝器
污垢
Engineering thermophysics
Enhanced heat transfer
Experiment study
Twisted tube
Condenser
Fouling
