Study On Heat Transfer Characteristics In Wavy Fin Channel Of Plate-Fin Heat Exchanger Used For High Speed Trains

Due to the rapid development of high-speed trains,its cooling technology has been widely concerned,and the plate-fin heat exchangers are favored by the advantages of high heat exchange efficiency,compact structure and light weight.This paper takes the channel formed by wavy fins of a plate-fin heat exchangers as an object.The heat transfer and flow characteristics in the wavy fin channel were compared to them in the channel formed by the plains fins.In the range of Reynolds number from 300 to 2200,the effects of wavy fin geometry(wave amplitude,wave wavelength,fin height,fin width)on heat transfer and flow of wavy fin channel are studied.The following conclusions are obtained.With the increase of Reynolds number,the average Nusselt number of wavy fin channel increases,while the drag coefficient decreases,the trend of plain fin channel is the same as that of wavy fin channel;and the average value of both the Nusselt number and the drag factor of wavy fin channel are significantly higher than that of the plain fin channel.When the wave amplitude increases and other geometric parameters are constant,it is found that the larger the wave amplitude is,the larger the average Nusselt number is,and the larger the resistance factor is.When the wave wavelength is reduced and other geometric parameters are unchanged,it is founded that the smaller the average Nusselt number,the larger the drag factor;When the wave amplitude increases and other geometric parameters are constant,it is found that the fin width has little effect on the drag factor,when Re<800,the smaller the fin width,the larger the average Nusselt number,Re>800,the larger the fin width,the larger the average Nusselt number;when changing the fin height,other geometry parameters are constant,it is found that the larger the fin height,the larger the average Nusselt number and the larger the drag factor.Taking the fin height as an example,when the heat transfer factor is used as the evaluation index under the condition of equal pumping power,it is found that the evaluation factor increases with the increase of the Reynolds number,and there is a case of more than 1,which indicates the heat exchange capacity of the wavy fin is better than that of plain fin for enhanced heat transfer.Under the same structural parameters,the influence of geometric parameters on the secondary flow intensity is the same as the average Nusselt number.As the Reynolds number increases,the secondary flow gradually increases in strength,and the secondary flow intensity of the corrugated fins is significantly higher than the secondary flow intensity of the flat fins.This shows that the heat transfer enhancement in the wavy fin channel is caused by the secondary flow.