管内层流强化传热的数值模拟

Numerical Simulation of Laminar Heat Transfer Enhancement in Tube Side

通过数值模拟,研究了85%甘油在含旋流片缩放管管内的传热与流阻特性,并与光滑管、缩放管的传热与流阻特性进行了对比。研究结果表明,层流时含旋流片缩放管的综合因子大于缩放管,且缩放管内插入6个小角度旋流片具有更好的传热性能。在有旋流片段可以通过减薄边界层厚度与增加有效传热温差的双重途径提高传热速率,而在旋流片下游段则可以利用有效传热温差的缓变特性继续维持较大的传热速率,从而能避免过多的流体置换次数,极大幅度的降低流体的输送功耗。

The heat transfer characteristics and flow resistance of 85% glycerin in converging-diverging tubes with spaced twisted tapes being inserted was investigated by numerical simulation,and the results were compared with the smooth tube and without the twisted tape.The simulation results indicated that the heat transfer valuation factor of converging-diverging tube with inserting twisted tape was greater than converging-diverging tube in laminar,and converging-diverging tube with being inserted 6 little angle twisted tape was well performance on heat transfer characteristics.Two methods were presented to improve heat transfer rate in tube with spaced twisted-tape,reduce the boundary layer thickness and increase effective heat transfer temperature difference.In the spaced twisted-tape downstream segment,making use of the characteristic of effective heat transfer temperature difference varying slowly to maintain a larger heat transfer rate,which can avoid excessive fluid replacement times and reduce greatly the power of transport fluid.