上行光管内置铝制扭带的换热与阻力试验研究

针对换热器在工业生产中不可避免地产生污垢,严重影响换热器性能的情况,内置扭带是一种已被证实兼有防垢除垢及强化传热的双重作用的技术。介绍了铝制扭带的换热试验研究方法。在改造的传热试验设备中,通过将9种不同结构参数的铝制扭带放置到换热管内,调节冷水阀,观察扭带在预计流量起转时进行传热试验。结果表明,内置扭带的换热管的总传热系数大于光管的数值,增大范围为9%~20%,内置扭带具有良好的强化传热作用。采用线性回归得到了与扭带结构参数相关的摩擦因数和努塞尔准数关联式,并通过性能评价,得到了评价因子=1.13~1.25,证明铝制扭带具有强化传热的实用价值。

Experimental study of heat transfer and flow resistance characteristics of upward-flow plain tube with aluminium twisted-tapes

The self-rotating tape inserted in the heat exchanger tube can prevent the fouling and enhance the heat transfer.The experimental tests are carried out in the modified heat transfer test equipment,and the heat transfer tube is respectively inserted with 9 aluminium twisted-tapes with different structural parameters.The cold water is flowing upwards in the tube and the saturated steam outside.After measuring and analyzing the test data,the characteristics of heat transfer and flow resistance of the upward-flow heat transfer tube inserted with different aluminium twisted-tapes are compared,the correlations of Nu number and friction factor relevant with the structural parameters of the tape are obtained using linear regression,and evaluation factor φ is got as 1.13～1.25 according to the performance evaluation,which proves the aluminium twisted-tapes have practical application value of heat transfer enhancement.