辊道窑尾部热交换器传热特性及涡流强化

Heat Transfer Characteristics and Eddy Current Enhancement of Heat Exchanger at the End of Roller Kiln

辊道窑烟气余热回收作为建陶企业节能降碳重要技术举措,回收烟气离不开热交换器。为提升AlN陶瓷换热器的流动传热性能,分析了翅片管AlN陶瓷换热器的热阻占比,通过建立翅片管AlN陶瓷换热器的流动传热模型,模拟研究了翅片间距、翅片厚度、管间距和涡流发生器对换热器流动传热性能的影响。结果表明:AlN换热器管外空气换热热阻为主要热阻,占比达到85%以上;当翅片间距、管横向间距、管纵向间距增大时,Nu增大,压降减小,三者对Nu值和压降影响较大;当翅片厚度增大时,Nu减小,压降增大,但翅片厚度对Nu值和压降影响较小;在所模拟的结构参数中,当翅片间距为5 mm、翅片厚度为1.2 mm、管横向间距为12 mm、管纵向间距为16 mm时,AlN陶瓷换热器综合性能最好。相同计算工况下,与光管AlN陶瓷换热器相比,翅片管AlN陶瓷换热器的总传热系数提升了378.24%~466.41%,与翅片管AlN陶瓷换热器相比,涡流发生器翅片管AlN陶瓷换热器的总传热系数提升了32.78%~88.76%。

As an important technical measure for energy saving and carbon reduction in ceramic enterprises,the recovery of flue gas from the heat exchanger is inseparable.In order to improve the flow heat transfer performance of AlN ceramic heat exchanger,the thermal resistance ratio was analyzed.The effects of fin spacing,fin thickness,tube spacing and eddy current generator on flow heat transfer performance of the heat exchanger were simulated and studied by establishing the flow heat transfer model of the finned tube AlN ceramic heat exchanger.The heat transfer thermal resistance of air outside the tube of AlN heat exchanger is the main thermal resistance,accounting for more than 85%.When the fin spacing,tube transverse spacing,and tube longitudinal spacing are increased,Nu increases and the pressure drop decreases,which has a great influence on Nu value and pressure drop.When the fin thickness increases,the Nu decreases and the pressure drop increases,but the fin thickness has little effect on the Nu value and pressure drop.In the simulated structural parameters,the comprehensive performance of AlN ceramic heat exchanger is highest,when the fin spacing is 5 mm,the fin thickness is 1.2 mm,the transverse spacing of the tube is 12 mm,and the longitudinal spacing of the tube is 16 mm.Under the same calculation conditions,the total heat transfer coefficient of the finned tube AlN ceramic heat exchanger is increased by 378.24–466.41%compared with the plain tube AlN ceramic heat exchanger,while the total heat transfer coefficient of the eddy current generator finned tube AlN ceramic heat exchanger is increased by 32.78–88.76%compared with the finned tube AlN ceramic heat exchanger.