电机冷却用翅管换热器传热和阻力特性研究

Study on heat transfer and friction characteristics in fin-tube heat exchangers used for electrical machines cooling

研究了一种电机冷却用新型翅片开孔结构换热器的性能,对三种结构的翅片管换热器进行了换热和阻力性能测试,新型翅片换热器结构为翅片间距2.1 mm且翅片上具有开孔结构,对照组换热器分别为翅片间距2.1 mm无开孔换热器和翅片间距2.3 mm无开孔换热器。试验结果表明,相同Re数下,该种具有开孔结构换热器在所有换热器中换热性能最好,较2.1 mm无孔提升38%～39%,但同时压降损失也最大,较2.1 mm无孔提升41.9%～42.9%。采用j/f评价综合性能,结果显示,Re>6700时,新型翅片换热器性能优于同翅片间距无开孔换热器。文章还对这三种结构翅片管换热器进行了传热和阻力关联式拟合,可为相关理论研究和工程选用提供参考。

The characteristics of fin-and-tube heat-exchanger with new perforated fin used for electrical machines cooling were discussed.Three fin-and-tube heat-exchangers with different fin structures,perforated fin with 2.1 mm fin spacing,plain fin with 2.1 mm fin spacing and plain fin with 2.3 mm fin spacing,were tested.The test results show that heat-exchanger with new perforated fin has the best heat transfer performance and the highest pressure drop among the three structures.Heat transfer was augmented by 38%～39% compared with the plain fin with fin spacing of 2.1 mm,while pressure drop increased by 41.9%～42.9%.The comprehensive performance comparison showed the new perforated fin was better than plain fin with 2.1mm fin spacing for the Reynolds number higher than 6700.The heat transfer and friction factor correlations for three different fin structures were obtained in a wide range of Reynolds number,which could make help for further research and engineering applications.