板翅式换热器翅片表面性能的试验研究

高效、紧凑板翅式换热器已在许多工业领域中得到广泛地应用。为给设计提供基本数据,我们进行了三种翅式形式(据齿形、开孔形及平直形)的七种翅片表面的试验研究,得出了传热因子j和摩擦因子f相对于雷诺数R_e的试验曲线。采用了由Soland等人提出的翅片表面性能的比较方法,对所试验的表面性能作了评价及比较。本文还对改进翅片表面性能的方法作了讨论。     

平行流冷凝器百叶窗翅片结构优化

建立平行流冷凝器百叶窗翅片的三维流动和换热模型,并对不同迎面风速下百叶窗翅片的流动和换热性能进行数值模拟,计算结果与试验结果具有较好的一致性,验证计算模型和方法的正确性。在此基础上,建立8种结构形式的百叶窗翅片模型,并对其空气侧的换热和流动过程进行仿真,分析结构形式和排列方式对百叶窗翅片换热量和空气阻力的影响,结果表明:增加开窗区域数能够有效提高翅片的换热性能,增加百叶窗的转向区数目能够有效降低进出口的压降。     

温度交变对翅片管换热器性能影响的实验研究

试验研究了温度交变对铜管-铜翅片蒸发器和铜管-铝翅片蒸发器空气侧压降和换热性能的影响.实验结果表明,全新铜管-铜翅片蒸发器空气侧压降比全新铜管-铝翅片蒸发器空气侧压降大,但温度交变后两者空气侧压降几乎一致,具有相同的长效压降特性;温度交变会导致铜管-铜翅片蒸发器和铜管-铝翅片蒸发器换热性能下降,在风量为400m3/h时减少的最多,铝翅片蒸发器减少1091.5W,铜翅片蒸发器减少704.8W;与温度交变前相比,铜翅片蒸发器换热系数下降8.1％～25.2％,铝翅片蒸发器换热系数下降10.6％～40.7％,铜管-铜翅片蒸发器具有更好的长效特性.     

翅片管式换热器换热与压降特性的试验研究

通过工程应用实例,选取市场上最常用的一类翅片管式换热器,针对不同的管排数和翅片间距,对其换热以及压降性能进行试验研究,并针对换热性能的差异对空调系统的影响进行分析评估。研究结果对于空调系统的研发过程具有一定的指导意义。     

大直径圆孔翅片管的传热与流阻性能实验研究

针对制冷换热器积霜工况下运行的特点，设计了大直径圆孔翅片，经对比性试验研究、优化试验研究，获得了两种最优片型。优化片换热性能远优于平片，阻力增加不大，节省金属材料，具有开发价值。本文还利用有限元法对优化片的翅片效率进行了数值求解分析。     

翅片管式换热器的翅片耐腐蚀涂层研究

分析翅片管式换热器环境腐蚀的主要因素和常用防腐涂层的暴露试验数据,参考施加2种涂层的铜翅片-铜管换热器和铝翅片-铜管换热器的比对试验数据,对铜和铝的几种耐腐蚀涂层进行评价。有学者的研究表明,涂层铜翅片-铜管换热器的耐腐蚀性能优于涂层铝翅片-铜管换热器。同时介绍其他涂层,可为翅片管式换热器的防腐提供参考。     

锯齿与打孔翅片表面性能数值模拟

以两种翅片表面(锯齿翅片、打孔翅片)为研究对象,采用 FLUENT 软件模拟和分析不同结构参数和数对翅片表面传热与流动阻力的影响,得出不同结构参数和操作参数下两种翅片的表面性能曲线;分别分析了锯齿翅片的翅片高度、翅片间距、翅片厚度和切开长度以及打孔翅片开孔率对翅片表面流动与传热性能影响;分析比较了两种翅片的性能.     

计算机CPU热管散热器换热性能研究

电子计算机的集成化发展对CPU散热器传热性能提出了新的要求,散热器表面最高温度和表面均温性是保证CPU正常运行的重要参数。本文运用ANSYS软件对CPU热管式散热器和普通翅片散热器进行计算,对二者稳态温度场分布和不同功率下散热器中心点温度变化进行了分析比较,计算结果表明,在稳定状态时,热管式散热器比普通翅片散热器具有更好的热传导性能和表面均温性;在CPU高功率工作（50W）时,普通翅片散热器无法满足换热要求,而热管式散热器仍可达到良好换热效果。搭建实验台对热管式散热器表面温度进行了测定,实验测试数据与模拟计算数据基本吻合,证明了数值模型的正确性和可行性。本研究对于计算机CPU散热器传热性能分析及其优化设计具有一定指导意义。     

家用空调器中平行流冷凝器翅片参数对空气侧传热流动性能的影响

为了推广平行流冷凝器在家用空调器中的应用,根据经验传热及压降关联式,采用数值模拟的方法,研究家用空调器中平行流冷凝器翅片参数对其空气侧传热流动性能的影响规律.结果表明:适当减小平行流冷凝器的翅片高度和翅片间距,可提高其换热系数、增加压降,保证其换热性能变化较小.     

冷风机翅片管的数学模型及性能的比较法辨析

不同的翅片管材料及翅片形式都将直接影响着翅片盘管的性能优异,以铝管铝套片冷风机为设计依据展开讨论,对冷风机蒸发器翅片管的设计建立数学模型,重点论述了翅片管特性,并用比较法对翅片管的性能进行了分析,以求能在设计时选出最佳的翅片管设计方案。     

An investigation of the airside performance of the slit fin-and-tube heat exchangersEtude de la performance côté air d'échangeurs de chaleurs à tubes à ailettes à fentes

The airside performance of fin-and-tube heat exchangers having slit geometry is experimentally investigated in this study. A total of 12 samples were tested and compared. Effects of fin pitch and the number of tube row were examined. The test results indicated that the heat transfer performance increase with decrease of fin pitch for N=1. However, for N4, the effect of fin pitch on the heat transfer performance is reversed. In addition to the effect of fin pitch, the heat transfer performance decrease with increase of the number of tube row and the friction factors are relatively independent of the number of tube row. Based on the present test results and those from previous investigations, a general correlation is proposed to describe the airside performance of the slit fin configuration, the mean deviations of the proposed heat transfer and friction correlation are 5.5 and 3.8%, respectively.     

整体翅片式微通道换热器的数值模拟

采用CFD数值模拟的方法,对整体翅片式微通道换热器空气侧的流动与传热特性进行研究,用场协同的原理分析翅片参数(长度、高度、间距)对换热器性能的影响,并与传统微通道换热器空气侧性能进行对比。结果表明:在考查的翅片尺寸范围内,随着翅片长度的缩短、高度的增加、间距的减小,温度场和速度场的协同性随之改善,有利于换热效果的提高;与传统的微通道换热器相比,整体翅片式微通道换热器空气侧换热性能变差,但是阻力大大降低,总体性能有所改善。     

空气冷却器空气侧百叶窗翅片强化传热性能研究

对跨临界CO2空调系统中空气冷却器空气侧的百叶窗翅片建立流固耦合的三维模型并进行数值模拟,结果表明传热和阻力特性与实验关联式吻合较好;开发新型弧形百叶窗翅片,并对不同窗翅角度和弧度的弧形百叶窗翅片进行数值分析,发现新型弧形百叶窗翅片的换热特性与压降特性较一般的百叶窗翅片都有增加,平均表面传热系数增加幅度高达9．47％,平均压降增加最大幅度为3．2％,可见新型弧形百叶窗翅片传热元件具有良好的综合传热性能。     

φ7管风冷冷凝器翅片密度对整机性能影响的实验研究

通过实验,测试两器均采用φ7管径换热管的风冷冷风型单元机在不同冷凝器翅片密度情况下整机的制冷量及能效比值。根据实验测试数据,可直观评估冷凝器翅片密度的调整对整机性能的影响程度,为使用φ7管换热器的机型的全面开发提供重要的参数依据。     

新齿型内螺纹传热管蒸发性能研究

针对开发的瘦齿、交叉齿、光管及普通齿型内螺纹传热管单管蒸发传热实验数据进行了对比，相同工况下，各传热管管内换热系数均随着冷媒流量的增大而增大，交叉齿管换热系数比瘦齿管高出10％，瘦齿管换热系数高出普通齿管10％左右。四种齿型中，交叉齿管管内压降最大，光管其次，瘦齿管比普通齿管略有增加。相同结构尺寸，相同工况下，利用稳态分布参数模型，对以上四种内螺纹传热管蒸发器传热和流动性能进行了数值模拟分析比较。结果表明，交叉齿管蒸发器换热量最大，瘦齿管稍差，普通齿管其次，但均好于光管。整个流量变化范围内，4种蒸发器压降变化都相差不大，光管蒸发器压降变化较其它管型略有增加。研究结果对内螺纹传热管的开发和研究具有指导意义。     

Airside heat transfer and friction characteristics for enhanced fin-and-tube heat exchanger with hydrophilic coating under wet conditions

The airside heat transfer and friction characteristics of 14 enhanced fin-and-tube heat exchangers with hydrophilic coating under wet conditions are experimented. The effects of number of tube rows, fin pitch and inlet relative humidity on airside performance are analyzed. The test results show that the influences of the fin pitch and the number of tube rows on the friction characteristic under wet conditions are similar to that under dry surface owing to the existence of the hydrophilic coating. The Colburn j factors decrease as the fin pitch and the number of tube rows increase. For wavy fin, the Colburn j factors increase with the increase of the inlet relative humidity, but for interrupted fin, the Colburn j factors are relatively insensitive to the change of the inlet relative humidity. The friction characteristic is independent of the inlet relative humidity. Based on the test results, heat transfer and friction correlations, in terms of the Colburn j factor and Fanning f factor, are proposed to describe the airside performance of the enhanced fin geometry with hydrophilic coating under wet conditions. For wavy fin, the correlation of the Colburn j factor gives a mean deviation of 7.6%, while the correlation of Fanning f factor shows a mean deviation of 9.1%. For interrupted fin, the correlation of the Colburn j factor gives a mean deviation of 9.7%, while the correlation of Fanning f factor shows a mean deviation of 7.3%.     

翅片结构对翅片管换热器积灰与压降影响的实验研究

积灰对具有不同翅片结构的翅片管换热器均会造成长效性能的衰减。本文搭建了换热器积灰可视化实验台,研究了翅片结构对积灰量及积灰后空气侧压降的影响。测试样件的翅片类型包括平直翅片、波纹翅片和开窗翅片;翅片间距范围为1.3~1.8 mm。实验结果表明:开窗翅片管换热器表面最容易沉积粉尘并增大积灰后压降,与平直翅片相比,波纹翅片和开窗翅片表面粉尘沉积量分别提高了25.6%和52.8%、积灰后压降增量分别提高了44.4%和165.6%;对于开窗翅片,小翅片间距有利于积灰并增大积灰后压降,与翅片间距1.8 mm的样件相比,翅片间距1.5 mm和1.3 mm的样件表面粉尘沉积量分别提高了26.2%和43.2%、积灰后压降增量分别提高了24.1%和49.4%;在积灰过程中,随着粉尘沉积量的增加,翅片管换热器空气侧压降先增大后保持稳定。     

尾鳍的形状与运动参数对推进速度的影响

从推进速度的角度出发,实验研究了尾鳍摆动式水下推进器尾鳍的形状参数与运动参数对推进速度的影响,给出了实验结果,对尾鳍摆动式水下推进器的设计具有重要的意义。     

Experimental investigation of a cooled thick fin in dry and humid air flows

The results of a study are reported in which a cooled, thick vertical fin was tested in a closed loop tunnel with and without condensation from the air flowing over it. In particular, the temperature distributions for the dry and wet fin cases, together with the condensate film thickness in the wet fin case, were investigated. From a flow visualization investigation, it was found that the boundary layer separates at the leading edge, resulting in a higher air heat transfer coefficient. The wet fin test results also indicated that the mode of condensation was dependent on fin surface characteristics and that the wet fin performance was governed by the air flow parameter. Within the laminar air flow range, the condensate film flowed downward under the action of gravity. However, at higher air velocities, both gravity and shear forces affected the condensate flow, a variation in the condensate film in the direction of air flow being noticed.     

Performance and optimum design analysis of convective fin arrays attached to flat and curved primary surfaces

A model has been developed analytically to carry out the performance and optimum design analysis of four fin arrays, namely, longitudinal rectangular fin array (LRFA), annular rectangular fin array (ARFA), longitudinal trapezoidal fin array (LTRA) and annular trapezoidal fin array (ATFA) under convective cooling conditions. The performance parameters such as fin efficiency, fin effectiveness and augmentation factor are evaluated for a wide range of design variables. It has been observed that the conduction through the supporting structure and the convection from the interfin spacing have a pronounced effect on the performance of a fin array. The optimum fin dimensions in a fin assembly have been determined by consideration of the constant total height of the fin assembly and interfin spacing. From the results, it can be highlighted that the optimum fin dimensions in fin arrays differ from that of the individual fins.