高频焊接与激光焊接翅片管传热性能对比试验

对高频焊接与激光焊接翅片管的传热性能进行对比试验,得到了两个试件在不同管外空气流速下的传热数据,运用直接分离法将管外空气侧对流换热系数从总的传热系数中分离,获取管外空气侧换热系数,再通过拟合方法获得管外空气侧换热关联式。研究表明:激光焊接翅片管的传热性能优于高频焊接翅片管,当空气流速为3m/s时,激光焊接翅片管的管外空气换热系数比同翅片尺寸的高频焊接翅片管的管外换热系数约高9%。     

椭圆管散热器传热及阻力性能试验研究

对空气横掠片距不相等的叉排椭圆翅片管散热器的传热及阻力性能进行了试验研究,得到试件在一系列工况下的传热与管外流动阻力数据,并对试验数据进行分析计算,从总传热系数K中分离出管外空气侧的对流换热系数h,给出有工程应用价值的管外换热准则关系式及管外阻力准则关系式。认为椭圆管管外的平均换热效果优于圆管。在相同的流通截面积下椭圆管传热周边较长,换热面积相应增加,因此结构上允许布置得更紧凑。     

滴状翅片管传热及阻力特性的试验研究

对滴状翅片管的传热及阻力性能进行了试验,给出了不同风速、温度下的试验结果。探讨了对流换热系数的分离方法。依据实测的数据,将管外空气横掠管簇的对流换热系数从传热系数中分离了出来。对管外的对流换热特性、阻力特性进行了分析研究,并整理成了无量纲准则式。试验表明滴状翅片管的阻力较小,试件性能达到国际先进水平。     

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。     

直接空冷凝汽器翅片管积灰流动换热的数值研究

为了深入研究空冷凝汽器散热管束积灰时的流动换热特性,利用FLUENT软件数值模拟了翅片管外不同积灰厚度的流动换热情况,得到了夏季工况翅片管4种积灰厚度的对流换热系数、传热系数及流动阻力随迎面风速的变化曲线,非线性拟合得到了摩擦系数、努赛尔数与雷诺数之间的关联式。利用性能评价指标PEC,对翅片管束积灰前后的流动换热性能进行了比较。结果表明:随着迎面风速的增加,积灰前后的管外对流换热系数,传热系数以及流动阻力逐渐增加;随着翅片管外积灰厚度的增加,对流换热系数、流动阻力以及摩擦系数变大,传热系数变小。     

船用方形翅片管省煤器流动阻力与传热特性的试验研究

在传热风洞试验台上,采用恒壁温方法,对4排4列共16根方形翅片管组成的管束空气侧流动阻力与传热性进行了试验研究,根据试验结果,拟合得到了阻力系数与传热系数的关联式,并与前苏联1973 计算标准方法进行了比较,结果表明前苏联方法在低风速（＜25m/s）时是可靠的,在高风速时,计算公式的误差较大,此研究的高风速条件下的翅片管流动与传热牧场生提供了试验数据。图5参7     

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...     

翅片管冷凝器的实验研究

在风洞实验台上，对椭圆矩形翅片管束和圆管圆形翅片管束进行了对比性实验，归纳出了换热与阻力的无因次经验公式，对于管内蒸汽冷凝、管外空气横掠管束的工况，椭圆矩形翅片管具有较优的换热与阻力性能。最后，讨论了一些有关椭圆矩形翅片管冷凝器的优化问题     

直条缝翅片管换热器传热与流动阻力性能研究

为了解翅片间距、翅片厚度、翅片材料和基管材料对直条缝翅片管换热器的传热和流阻性能的影响,以及获得通用的换热与流动阻力计算关联式,对一种直条缝翅片管换热器进行了实验研究。通过风洞试验台共进行了7个试件的试验,试验过程中管内水的进口温度和速度保持60℃和1.5 m/s不变,进风温度保持21℃,入口风速为1.5～4.5 m/s。结果表明：在管外空气侧雷诺数Re_a为2647～8143范围内,随着翅片间距的增大,对流换热系数先增大后减小,存在一个峰值;翅片间距对阻力的影响与管外空气侧雷诺数有关,当Re_a≤5 000时翅片间距越小摩擦系数越大,当Re_a>5 000时,翅片间距越小,摩擦系数越小;翅片厚度的增加会增加对流换热系数和摩擦系数;紫铜(T2)翅片的对流换热系数高于8011铝合金(AL8011)翅片,但摩擦系数较低;T2基管的对流换热系数最高,铁白铜(B10)基管次之,316L不锈钢(316L)基管最低;不同的基管材料对摩擦系数没有影响。     

小管径穿片式翅片管三种间距下的换热与阻力特性

对3种基管外径(10 mm)和管间距相同、翅片间距不同的穿片式空气-水换热器的换热与阻力特性进行了试验研究,翅片间距分别为1.0、1.6、1.9 mm.得出了不同翅片间距下的管外换热系数和流动阻力系数以及相应的计算关联式,利用评价指标对3种试件的综合换热性能进行了评价.结果表明:翅片间距对管外换热性能的影响很大;在选择具有合理翅化比的换热器的翅片间距时还需考虑经济性和紧凑度等方面的因素.     

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.     

矩形钢翅片椭圆管簇的试验研究

本文着重阐述了电站凝汽器空冷系统的空冷式换热器所用的矩形钢翅片椭圆管簇小样的试验研究。通过对小样放热及阻力的试验，得出不同迎面风速下的放热性能及空气侧阻力性能的关系。     

全自动翅片管单管传热性能 试验系统的研制

所研制的全自动翅片管单管的传热性能试验系统可测试翅片管单管的传热系统、双金属翅片管的品质系数。测试数据的采集、测试过程的控制、数据的计算和报告的整理全部由计算机完成。介绍了该系统及其部分设备的构成,说明了部分参数的计算方法,分析了系统的精度。     

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。     

On the evaluation of a finned annular tube in convective heat transfer performance in the presence of Ag/oil nanofluid for a constant thermal flux rate boundary condition

In the present empirical work, the effectiveness of a finned annular tube in the presence of Ag/oil nanofluid is investigated. An annular tube with axial fins was considered as the test case. Suspended Ag nanoparticles in different volume concentrations of 0.011%, 0.044%, and 0.176% were examined in this work. The setup was designed in a way to be sure that the flow is hydrodynamically fully developed along the tube. This experiment has been done in a laminar flow regime in which Reynolds number was less than 160 for all the studied cases. The finned annular tube was wrapped with a coil that satisfied the condition of a constant thermal flux rate of 204 W on the outer boundary. Based on the acquired data, the convective heat transfer coefficient was obtained for all the nanofluid cases and compared to the base fluid. It was observed that the convective heat transfer coefficient substantially rises by increasing the nanoparticles. Which for the best case (volume concentration of 0.171% and Reynolds number of about 160), this factor was about a 33% enhancement compared to the base fluid.     

带有小螺旋角的内外螺旋翅片管高压加热器的工业试验

工业现场试验的结果表明,带有小螺旋角的内外螺旋翅片管（简称内外螺旋翅片管或ＩＯＳＦ管）用于电站高压加热器有着显著的传热强化效果,其实测总传热系数是光滑管加热器的１．４３倍,可相应节省换热面积３０％。在等面积下使用,则可收到明显的节能效果。     

Numerical investigation of heat transfer and pressure drop in enhanced tubes

This study investigates passive heat transfer enhancement techniques to determine the distribution of temperature and static pressure in test tubes, the friction factor, the heat flux, the temperature difference between the inlet and outlet fluid temperatures, the pressure drop penalty and the numerical convective heat transfer coefficient, and then compares the results to the experimental data of Zdaniuk et al. It predicts the single-phase friction factors for the smooth and enhanced tubes by means of the empirical correlations of Blasius and Zdaniuk et al. This study performed calculations on a smooth tube and two helically finned tubes with different geometric parameters also used in the analyses of Zdaniuk et al. It also performed calculations on two corrugated tubes in the simulation study. In Zdaniuk et al.'s experimental setup, the horizontal test section was a 2.74 m long countercurrent flow double tube heat exchanger with the fluid of water flowing in the inner copper tube (15.57–15.64 mm i.d.) and cooling water flowing in the annulus (31.75 mm i.d.). Their test runs were performed at a temperature around 20 °C for cold water flowing in the annulus while Reynolds numbers ranged from 12,000 to 57,000 for the water flowing in the inner tube. A single-phase numerical model having three-dimensional equations is employed with either constant or temperature dependent properties to study the hydrodynamics and thermal behaviors of the flow. The temperature contours are presented for inlet, outlet and fully developed regions of the tube. The variations of the fluid temperature and static pressure along tube length are shown in the paper. The results obtained from a numerical analysis for the helically tubes were validated by various friction factor correlations, such as those found by Blasius and Zdaniuk et al. Then, numerical results were obtained for the two corrugated tubes as a simulation study. The present study found that the average deviation is less than 5% for the friction factors obtained by the Fluent CFD program while Blasius's correlation has the average deviation of less than 10%. The corrugated tubes have a higher heat transfer coefficient than smooth tubes but a lower coefficient than helically finned tubes. The paper also investigates the pressure drop penalty for the heat transfer enhancement.     

水冷壳管式油冷却器传热强化实验

通过实验研究 ,比较了螺旋隔板花瓣管油冷却器和螺旋隔板低肋管油冷却器的传热和压降性能 ,实验结果表明 ,螺旋隔板花瓣管油冷却器比螺旋隔板低肋管油冷却器的总传热系数提高 10 %以上 ,而压降却低 46 %左右