螺旋鳍片管在烟气余热回收换热器中的应用

在锅炉烟气余热回收换热器中,螺旋型鳍片管和H型翅片管是常用的2种扩展受热面型式.理论分析和工程实践表明,螺旋型鳍片管的传热性能优于H型翅片管;而磨损和积灰等特性与受热面型式没有直接关系,是由烟气流场分布、锅炉燃用煤种以及吹灰器类型和布置方式等因素决定.螺旋型鳍片管更适用于低温省煤器、净烟气加热器等小温差传热场合.     

螺旋翅片管传热特性和阻力特性研究与应用

通过螺旋翅片管在工程中应用的例子介绍它的传热特性和阻力特性并给出了最佳结构尺寸。经工程应用表明，螺旋翅片管具有很强的工程应用价值和推广价值。     

开缝布置方式对开缝翅片管换热器 传热与阻力特性的影响

为了获得开缝布置方式对开缝翅片管换热器传热与阻力特性的影响规律,对5种不同翅片管换热器进行了数值模拟研究,并进行了模化试验验证。结果表明：增加开缝会提高翅片管换热器的传热性能,但阻力也随之增加;与开缝位置相比,开缝数量对开缝翅片管换热器传热与阻力特性的影响更大;在Re=4800~7500日时,开缝翅片管换热器综合流动传热性能 随着Re数的增大而增大;在5种翅片中,开缝翅片的综合流动传热性能高于普通平直翅片;数值模拟与试验结果偏差较小,采用数值模拟方法能够比较准确地分析开缝翅片管换热器的传热与阻力特性。     

管间距对开缝翅片管换热器传热与阻力特性的影响

为了获得管间距对开缝翅片管换热器传热与阻力特性的影响规律,对5种不同翅片管换热器进行了数值模拟研究,并进行了模化试验验证。结果表明:开缝翅片管束的传热和阻力特性与翅片侧气体的Re数有关,随着Re数增大,翅片侧Nu数增大,摩擦因子f逐渐减小;纵向间距S2对开缝翅片管换热器的综合流动传热性能的影响较大。数值模拟与试验结果偏差较小,采用数值模拟方法能够比较准确地分析开缝翅片管换热器的传热与阻力特性。     

椭圆翅片管空冷器流动传热特性的研究

用稳态的恒壁温法对3个椭圆翅片管空冷器和1个圆翅片管空冷器的传热和阻力特性进行了研究,得到空冷器空气侧的传热与阻力性能,在相同的迎风面流速下,椭圆翅片管比圆翅片管空气侧换热系数约大3－7倍;在相同的换热系数下,椭圆翅片管比圆翅片管的压降低。     

高肋翅片管的热流特性及工程应用

电站锅炉暖风器的传热管通常采用的肋化型式有椭圆管、绕片管、轧制管、以及目前在国外多种先进换热器中开始采用的钢铝复合管新型传热元件。该文作者介绍了４种高肋翅片管的热流特性，肋化管选择及其工程应用。     

非对称翅片管换热器传热和阻力特性的数值分析

基于COMSOL软件建立了一种非对称翅片管换热器的三维模型,对空气侧的流动和传热特性进行了数值研究,与平直翅片管换热器进行对比,并进一步分析了不同雷诺数下交错角β对非对称翅片管换热器性能的影响.结果表明:在Re为3 239~9 700内,与平直翅片管换热器相比,非对称翅片管换热器的传热因子增大,平均增大量为13.95%,阻力因子减小,且随着Re增大其减小效果更加明显,平均减小量为4.80%;以MJF作为评价标准,且其他结构参数不变时,β=30°时MJF最大,换热器的综合性能最好.     

烟气余热回收不同形式纵向翅片管模拟研究

基于理论分析和数值模拟,研究烟气余热回收采用不同形式纵向翅片管时,结构参数变化对热回收室传热性能和流动阻力的影响规律,并对比分析综合性能的优劣。结果表明相比于光滑管,平板式、百叶窗式、波纹翅片管的传热量均可增加约10%;其中,百叶窗式翅片管的传热性能和综合性能均最优,波纹翅片管次之,矩形平板式翅片管最差。     

螺旋翅片管束传热和阻力特性的试验研究

对13个不同翅片间距、翅片高度、横向管间距、纵向管间距的螺旋翅片管束换热器在不同雷诺数条件下的传热和阻力特性进行了试验研究,得出了翅片间距、翅片高度、横向管间距、纵向管间距及雷诺数与换热特性Nu和阻力特性Eu的准则关系式,并对准则关系式进行了分析.结果表明:随着横向管间距和翅片间距的增大,螺旋翅片管的传热得到强化,但随着纵向管间距和翅片高度的增加,螺旋翅片管的传热有所减弱;随着横向管间距、纵向管间距和翅片间距的增大,螺旋翅片管的阻力减少,但随着翅片高度的增加,螺旋翅片管的阻力增加.     

圆弧型开缝翅片管空气冷却器传热与阻力特性试验研究

对3种不同翅片间距的圆弧型开缝翅片管空气冷却器进行试验研究,得到迎面风速在1.0~3.0 m/s空气侧传热与阻力特性变化规律,分析了迎面风速、翅片间距对换热器传热与阻力特性的影响;雷诺数Re在1200~3800,综合性能指标随着Re的增大而增大;当Re1800时,Pf=1.7 mm的综合流动传热性能最好,当Re1800时,Pf=2.5 mm的综合流动传热性能最好;圆弧型开缝翅片管的综合流动传热性能比平直翅片管高。     

纵向翅片管传热计算研究与工业应用

主要研究了纵向翅片管的传热计算流程及工程应用.根据纵向翅片管的基本传热机理,系统深入地总结了纵向翅片管在不同传热条件下换热系数的计算方法,提出了纵向翅片管换热器的设计流程;通过具体工程实例,纵向翅片管换热器的设计理论得到验证,同时计算结果表明,与传统的光管相比,纵向翅片管传热系数高,设备传热性能好,是一种行之有效的节能...     

椭圆钎焊与双金属轧制翅片管传热与阻力性能的试验对比

对椭圆钎焊翅片管和双金属轧制翅片管换热器的传热及阻力性能进行试验对比研究,试验得到了一系列工况下的传热数据与管外空气流动阻力数据,给出了相应的传热系数、流动阻力曲线。从总传热系数中分离出管外空气侧的对流换热系数,得到了具有一定应用价值的管外换热的计算关联式;拟合得到了管外阻力计算关联式。结果表明:椭圆钎焊翅片管比双金属轧制翅片管的传热系数约高9%,管外换热系数约高17%,且管外空气流动阻力约低11%。     

H型鳍片管的传热与流动特性试验研究

H型鳍片管是一种新型高效强化传热管。对一定结构的H型鳍片管与螺旋翅片管换热器进行了比较性半工业试验研究,得到了H型鳍片管换热与阻力准则关系式,并与相同结构参数的螺旋翅片管进行比较。根据实验结果得出:H型鳍片管换热与阻力特性均优于同结构参数的螺旋翅片管。     

新型轴对称内翅管换热过程的数值模拟

采用数值模拟的方法,对新型整体式轴对称不等高内展翅片换热管的管内流动、换热及阻力特性进行了研究,并将模拟结果分别与实验测量值和光管经验公式计算值进行了比较,结果表明:数值模拟结果与实验测量结果和经验公式计算结果符合得较好;新型内翅片管的强化换热效果最好,其换热系数约为光管的1.67~2.27倍,为中心对称翅片管的1.17~1.35倍;内翅片管的阻力系数是光管的1.44~2.20倍,中心对称和新型内翅片管具有基本相同的阻力系数;8翅和10翅新型内翅片管的综合性能参数较优.     

Heat Transfer Performance of an Edge-Shaped Finned Tube

The third-generation heat transfer technologies, such as three-dimensional fin and dimple, are still important means of improving energy efficiency and will continue to be challenging issues. This paper presents condensation heat transfer performance of an edge-shaped finned tube fabricated by a ploughing–extruding process. The edge-shaped finned tube integrates more than one heat transfer enhancement technology and can enhance the heat transfer capacity greatly. It is seen that the overall heat transfer coefficient and heat flux increase with inlet velocity of cold water increasing, and decrease with inlet temperature of cold water increasing, whereas the shell-side heat transfer coefficient decreases with inlet velocity of cold water increasing and increases with inlet temperature of cold water increasing. At the same inlet velocity, the shell-side heat transfer coefficient for the edge-shaped finned tube is improved by 5–7 times compared to that of a smooth tube. At the same temperature difference between wall and vapor, the shell-side heat transfer coefficient is also higher than what had been reported in the literature. The shell-side heat transfer coefficient of the edge-shaped finned tube decreases with the increase of fabrication parameter feed at the same inlet velocity or inlet temperature of cold water.     

径向错列翅片管内凝结对流换热数值模拟分析

采用数值模拟方法,对径向错列翅片管内含不凝结气体水蒸气的凝结对流换热及阻力特性进行了综合分析。将编写的自定义函数(UDF)导入ANSYS FLUENT软件,对新型强化管传热性能和阻力性能进行了数值模拟,并根据管长方向壁面上蒸汽质量分数的变化情况,讨论分析了凝结过程中翅片管传热性能的变化规律。分析结果表明:与光管相比,内翅片管的强化传热效果随翅数增多、翅片换热接触面积增大而更加显著;另一方面,翅片管的流动阻力相应增大,对管路换热产生不良影响。在所研究翅型范围内16翅y=2x~2型翅片管综合强化换热效果更优;此外随着换热过程的持续,蒸汽凝结逐渐放缓;入口速度增大导致水蒸气凝结不充分,对换热效果的提升有一定制约。     

Heat transfer analysis of H-type finned tube embedded in packed bed for gasification to produce hydrogen

Gasification for hydrogen production by the H-type finned tube embedded in the packed bed is considered to be more economical. Based on the thermal flow reversal reactor, the heat transfer characteristics of H-type finned tube embedded on the both sides of high-temperature zone of the packed bed under the quasi-steady were researched. The contribution of radiation heat transfer rate on the H-type finned tube is about 60.5% at most and radiation mainly occurs on the central tube. Within the range of inlet temperature and Re, the fin-assisted degree is both decreased gradually and the maximum is 48.9%. When the temperature is above 906 K or within the range of Re, the heat transfer rate of the fin is mainly from the radiation heat transfer rate. Under the condition of high inlet temperature and high Re, the fin-assisted degree is minimum, which indicates the operation stability of the H-type finned tube is better.     

Numerical Analysis of Turbulent Flow in a Small Helically Segmented Finned Tube Bank

A full finned tube bank is represented as a small finned tube bank in order to analyze numerically mean properties behavior in the streamwise direction. The main goal is to obtain criteria for implementing periodic boundary conditions in a single isolated finned tube module. The simulation is carried out with the Reynolds Averaged Navier–Stokes method and the turbulence effect is modeled with the Renormalization Group k-? model. The complex geometry of finned tube is represented by means of a cut-cell method. Numerical results are compared with experimental data, experimental visualizations, and semi-empirical correlations. Predictions show an adequate hydrodynamics and heat transfer representation. Additionally, mean properties in the streamwise direction show quasi-sinusoidal behavior, and the heat transfer presents approximately identical values in every finned tube in the fully developed flow zone. Therefore, periodic boundary conditions for turbulent kinetic energy and its dissipation rate and a constant wall heat flux condition in the fully developed flow are proposed in numerical simulations on a single isolated finned tube module.     

内展翅片换热器应用在压缩空气系统中的节能效益分析

文中通过实验数据分析以及实际工程案例,就内展翅片换热器在压缩空气系统的相同工况下,采用光管换热器和外翅片换热器的换热效果及阻力特性进行了比较,结果表明,内展翅片换热器不仅具有较好的强化传热效果,而且单位压降损耗低,节能效果显著。