螺纹槽管错列管束的传热特性及流动阻力特性研究

【作者】 安越里；

【导师】 黄新元；

【作者基本信息】 山东大学 ， 热能工程， 2006， 硕士

【摘要】 随着电力生产规模的日益增加，制造换热功率大、体积小、流动阻力低、高效紧凑的锅炉空气预热器将具有重要意义，而采用强化传热技术无疑是实现这一目标的最有效途径。 螺纹槽管作为一种有效的强化传热元件被广泛使用。在以前的研究中都是对螺纹槽管单管的传热及流动阻力特性进行了大量的研究，对于螺纹槽管管束的传热及流动阻力特性的研究几乎没有。螺纹槽管一般是以管束的形式应用于空气预热器等换热设备，而管束中各个螺纹槽管之间流体的流动及换热是互相影响的，因此用单管的传热及流动阻力特性来指导换热器的设计有较大的误差，因此，我们就要对管束的换热以及流动阻力特性进行具体研究。 本文以试验为基础，首先对几种不同规格的螺纹槽管单管的换热特性及流动阻力特性进行了研究，得出了换热特性及流动阻力特性的无量纲关系式，然后以现在电厂空气预热器上最常用规格的螺纹槽管制作试验管束，管内采用高温空气纵向冲刷管束，管外为低温空气横向冲刷管束，改变错列管束的横向管节距及纵向管节距，从而得到各个管束外部的努谢尔特数以及欧拉数与各个因素的无量纲关系式，通过分析可得到横向管节距及纵向管节距对换热特性及流动阻力特性的影响趋势。 当管节距不是很大(结构参数σ′＜1.45)时，纵向节距的增大对强化传热是有利的，即横向节距不变的情况下，随着纵向节距的增大，换热系数增大。但当管节距较大(σ′＞1.45)时，纵向节距的增大对强化传热是不利的，即随着纵向节距的增大换热系数反而减小，而且还会增大流动阻力。 横向节距的增大对强化传热是有利的，即随着横向节距的增加换热系数始终是增大的，对减小流动阻力也是有利的，即随着横向节距的增加阻力系数始终是减小的。通过关系式可以看出，横行节距的变化对流动阻力的变化起到主导作用，但横向节距也不能无限制的增大。 利用结论，得到较合理的管束的横向管节距和纵向管节距，为螺纹槽管在空气预热器中的应用提供设计依据，以达到最佳的换热特性和阻力特性的综合效果，取得最好的经济效益。更多还原

【Abstract】 With the scale of electric power plants getting larger and larger, it is important to producing larger power, small shape, low fluid resistance and high efficiency air preheater of boilers. Heat transfer augmentation has been the hotspots for investigation of heat transfer.Spirally fluted tube has been comprehensiveness used as effective enhanced heat transfer element. In former considerations, they had did a lot of researches about the heat transfer regularity and the fluid resistance characteristics of the single spirally fluted tube, but researches on the heat transfer regularity and the fluid resistance characteristics of the tube banks were little or nothing. Generally, spirally fluted tubes are used as tube banks in preheater or other heat transfer equipments, so if we use the heat transfer regularity and the fluid resistance characteristics of the single spirally fluted tube to instruct the designs of the heat transfer equipments, it will be major errors. Therefore, we should do some researches about tube banks.Based on the experiments, this paper researches the heat transfer regularity and the fluid resistance characteristics of the single spirally fluted tube, and educed the no-dimension formulas of the heat transfer regularity and the fluid resistance characteristics. Then we use the spirally fluted tubes which is in common used in the air preheater, high temperature air flows inside the tubes and low temperature air cross-scours the outside of the tubes, change the landscape orientation distance and the longitudinal distance of the stagger arrangement tube bank, then get Nusselt number and Euler numbers of the tube banks, then analyze the infection trends of the landscape orientation distance and the longitudinal distance to heat transfer更多还原