横纹槽管内插断续扭带复合强化传热的实验研究

Experimental Study of the Complex Intensified Heat Transfer by Intermittently Inserting Twisted Strips into a Transversely Slotted Tube

本研究以导热油为工质,在层流和过渡流(Re<7 000)范围内研究横纹槽管内插三种不同规格的断续扭带和同扭率(Y=4.13)连续扭带的流动与强化换热特性。将实验数据进行回归分析得到了阻力系数和Nu的实验关联式,为复合强化传热的计算提供了理论依据。研究表明:横纹槽管内插扭带的综合换热性能优于内插相同扭带的光管,横纹槽管内插长度为66 mm的断续扭带的综合换热性能要优于同条件下内插连续扭带的光管。实验结果可为换热器的改造和新型换热器的设计提供理论依据。

An experiment was performed with a heat-conduction oil serving as the working medium. In a range of the Re number between the laminar flows and transition flows( Re < 7000),the flow and intensified heat exchange characteristics of a transversely slotted tube internally inserted with intermittent twisted strips in three different specifications and continuous twisted strips at the same twist rate( Y = 4. 13) were investigated. Experimental coorelation formulae of the resistance coefficient and the Nu number were obtained respectively by performing a regressive analysis of the test data,thus offering a theoretical basis for calculating the complex intensified heat transfer. It has been found that the comprehensive heat exchange performance of a transversely slotted tube internally inserted with the twisted strips is superior to that of a bare tube internally inserted with the same twisted strips. The comprehensive heat exchange performance of a transversely slotted tube internally inserted with the intermittent twisted strips in a length of 66 mm is superior to that internally inserted with the continuous twisted strips. The test results can provide a theoretical basis for the reconstruction of heat exchangers and design of novel heat exchangers.