新型管芯式散热器热工性能试验研究

通过试验,对新型管芯式散热器进行了研究,根据国家标准建立了一套汽车散热器热力性能试验系统;运用该系统对管芯式散热器进行了较为系统的试验研究,获得了它的三种水管排数下的传热与阻力特性的试验数据;运用最优化方法通过计算机编制程序,对数据进行处理和计算,从而得到了管芯式散热器的三种管排数的空气侧与水侧的对流换热准则方程式.     

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。     

新型矿用车管芯式散热器阻力性能的数值模拟

利用ANSYS Flotran模块对不同速度下的管芯式散热器的空气流动速度和压降进行数值模拟,模拟值与试验值吻合,表明利用ANSYS对管芯式散热器阻力性能进行模拟的方法是可行的。     

基于BP神经网络的汽车散热器性能研究

利用较新的BP神经网络预测方法,构造了汽车散热器预测模型,对管带式、管芯式汽车散热器进行了预测,预测值和试验值吻合,说明利用BP神经网络方法对汽车散热器性能进行预测,方法是可行的。     

LDV散热器传热特性的分析研究

散热器是发动机是重要部件总成。本文对上海汽车商用车技术中心LDV车用散热器的传热性能进行风洞试验,由实测试验数据,将管外横掠管簇的对流换热系数从传热系数中分离出来,整理成无量纲准则式,为散热器的优化设计提供参考依据。另外,对一些未做过性能试验的散热器的设计计算也能提供帮助。     

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。     

汽车散热器结构优化研究

散热器是汽车发动机冷却系统的重要组成部分.采用多孔介质模型对汽车散热器进行简化,对其温度场和流场进行了仿真计算.分别模拟计算了进、出水口位置以及水管排数不同时散热器的换热性能,分析比较了它们的换热特性和流动特性以获得进、出水口位置及水管排数对管带式散热器性能的影响,研究了散热器结构优化的方向.利用风洞试验台进行了试验,并将试验值和数值模拟值进行了对比分析,验证了数值模拟的正确性.     

螺旋管式熔盐-氦气换热器对流传热试验研究

对一台螺旋管式熔盐-氦气换热器进行试验研究,并利用威尔逊法对试验数据进行处理,获得螺旋管式换热器用于熔盐-氦气对流传热的传热准则关系式。将关系式与经验公式对比分析,结果表明螺旋管式换热器在管程和壳程均能提高工质对流换热系数,同时为熔盐-氦气换热器的设计提供设计依据。     

车用管带式散热器性能研究

以管带式汽车散热器为研究对象,采用理论分析和试验研究相结合的方法研究了散热器的流动和传热性能,并通过线性拟合建立了传热特性的数学模型。通过对试验数据进行分析计算,并对计算结果作线性拟合处理,从而建立适用于某品牌的散热器生产要求的流动和传热特性的关系式。模型预测结果与试验结果吻合较好,表明了模型关系式的正确性。     

汽车管带式散热器仿真设计方法的研究

利用CFD手段对结构复杂的管带式散热器仿真设计方法进行了研究,采用散热器局部完全仿真计算分析得到管带与空气的热交换系数,并从温度、压力和速度三方面分析了散热片开窗角度对其换热性能的影响,得出开窗23°时换热效果最好,又利用多孔介质模拟开窗散热带,进行整体散热器的传热性能仿真模拟计算.研究结果表明:计算结果与试验结果比较吻合,为散热器产品的优化设计提供了可能.     

Experimental Study on the Air-Side Performance of a Multipass Parallel and Counter Cross-Flow L-Footed Spiral Fin-and-Tube Heat Exchanger

This study conducted experiments on the air-side performance of novel L-footed spiral fin-and-tube heat exchangers that were faced with airflow at high Reynolds numbers (3500–13,000). The examined heat exchangers have a multipass parallel-and-counter cross-flow type of water flow arrangement. This flow arrangement is a combination of the parallel cross-flow and the counter cross-flow. This type of water flow arrangement may be the best fit for the reverse-flow system, because it can provide constant heat-exchange effectiveness for every flow reversal direction at the same airflow rate. Ambient air was used as a working fluid on the air side and hot water for the tube side. This way the effect of the number of tube rows on the heat transfer and friction characteristics of L-footed spiral fin-and-tube heat exchangers was clearly observed. The effect of the fin's outside diameter on the pressure drop was also studied. The results show that the number of tube rows has no significant effect on the air-side heat transfer or on friction characteristics at high Reynolds numbers. However, the fin's outside diameter shows a significant effect on the pressure drop. The pressure drop increases as the fin's outside diameter increases for the same number of tube rows.     

Fin Pattern Effects on Air-Side Heat Transfer and Friction Characteristics of Fin-and-Tube Heat Exchangers with Large Number of Large-Diameter Tube Rows

Air-side heat transfer and friction characteristics of nine kinds of fin-and-tube heat exchangers, with a large number of tube rows (6, 9, and 12, respectively) and large diameter of tubes (18 mm), are experimentally investigated. The test samples consist of three types of fin configurations: plain fin, slit fin, and fin with delta-wing longitudinal vortex generators. The working fluid in the tube is steam. Results show that when the number of tube is larger than 6, the heat transfer and friction performance for three kinds of fins is independent of the number of tube rows, and slit fin provides higher heat transfer and pressure drop than the other two fins. The heat transfer and friction factor correlations for all the heat exchangers were acquired with Reynolds numbers ranging from 4000 to 10000. The air-side performance of heat exchangers with plain fin, slit fin, and longitudinal vortex-generator fin were evaluated under three sets of criteria, and the results showed that the heat exchanger with slit fin has better performance than that with vortex-generator fin, especially at high Reynolds numbers.     

管排数对三角小翼式涡产生器式管片换热器换热影响的数值分析

通过数值模拟的方法,研究了三角小翼式涡产生器式错排圆管管片换热板芯在1,2,3,4四种不同管排数下的局部对流换热系数以及平均对流换热系数、阻力系数,得出管排数对换热与阻力性能的影响规律,为进一步提高换热器换热性能提供了理论依据。     

Parametric study and multiple correlations of an H-type finned tube bank in a fully developed region

ABSTRACT

The air-side heat transfer and pressure drop characteristics of an H-type finned tube bank in the turbulent periodically fully developed region are investigated numerically. The effects of seven geometric parameters and Reynolds number are examined. It is found that when the number of tube rows is equal to and larger than 25, the heat transfer and fluid flow approach the fully developed state. Among the seven geometric parameters spanwise tube pitch has the most important effect. Based on the numerical results, the correlations of heat transfer and pressure drop of the H-type finned tube bank for the fully developed region are presented.     

汽车水散热器设计软件开发

为了降低散热器的设计成本并提高计算精度,利用PowerBuilder开发了汽车水散热器设计软件,其计算功能包括校核计算、翅片间距优化计算、翅片高度优化计算、管长优化计算及管排数优化计算。对比分析试验表明:计算结果具有较高的精度。计算分析翅片间距、开窗角度、风速及冷却液中乙二醇百分比对散热器性能的影响。研究表明:减小翅片间距及增大风速可提高换热性能;减小开窗角度可降低风侧阻力;增大乙二醇百分比可降低冷却液出口温度。     

Effect of a delta-winglet vortex pair on the performance of a tube–fin heat exchanger

The experimental analysis of the effects of delta-winglet vortex generators on the performance of a fin and tube radiator is presented. The winglets were arranged in flow-up configuration, and placed directly upstream of the tube. This is a hitherto untested configuration, but is thought to have certain advantages. In addition to vortex generation the flow is guided onto the tube surface increasing the localised velocity gradients and Nusselt numbers in this region. The study includes dye visualisation and full scale heat transfer performance measurements. The results are compared to a standard louvre fin surface. It was found that the winglet surface had 87% of the heat transfer capacity but only 53% of the pressure drop of the louvre fin surface.     

椭圆管与扁管管板式换热器换热性能的分析比较

本文对椭圆管与扁管管板式换热器的充分发展的周期性层流流动与换热特性进行了数值计算分析,给出了在400相似文献   

Comparisons of thermal performance and pressure drop of counterflow and parallel-flow heat-pipe heat exchangers with aligned/staggered tube rows

This paper presents a numerical calculation and comparison of thermal performance and pressure drop for heat-pipe heat exchangers with aligned/staggered tube rows. In this study, the variations of the number of rows and columns from 1 to 6 for a total 36 arrangements are presented and discussed. From the present results, an optimum arrangement of heat-pipe heat exchangers could be obtained.     

Heat transfer and pressure drop performance of twisted oval tube heat exchanger

Twisted oval tube heat exchanger is a type of heat exchanger that aims at improving the heat transfer coefficient of the tube side and also decreasing the pressure drop of the shell side. In the present work, tube side and shell side heat transfer and pressure drop performances of a twisted oval tube heat exchanger has been experimentally studied. The tube side study shows that the tube side heat transfer coefficient and pressure drop in a twisted oval tube are both higher than in a smooth round tube. The shell side study shows that the lower the modified Froude number Fr_M, the higher the shell side heat transfer coefficient and pressure drop. In order to comparatively analyze its shell side performance of the heat exchanger, a rod baffle heat exchanger with similar size of the twisted oval tube heat exchanger is designed and its performance is calculated with Gentry's method. The comparative study shows that the heat transfer coefficient of the twisted oval tube heat exchanger is higher and the pressure drop is lower than the rod baffle heat exchanger. In order to evaluate the overall performance of the twisted oval tube heat exchanger, a performance evaluation criterion considering both the tube side and shell side performance of a heat exchanger is proposed and applied. The analyze of the overall performance of the twisted oval tube shows that the twisted oval tube heat exchangers works more effective at low tube side flow rate and high shell side flow rate.     

Concentration solar dryer water-to-air heat exchanger: Modeling and parametric studies

In this paper we present a modeling and parametric studies of a water-to-air heat exchanger. This exchanger is formed of a fan blowing the air to be heated through a battery of smooth tubes where the hot water—coming from solar concentrators—circulates. The heated air is injected into a thermal room to dry the clay bricks.In the first part, we study the most used models in the estimation of the heat transfer and air flow pressure drop across a tube bundle, and subsequently calculate the required transmitted power to the air.In the second part, we focus on the parametric study of the influence of the different geometric parameters of the exchanger on the heat flow rate, the air outlet temperature, the pressure drop and the requested transferred power to the air. The considered parameters are: The water heat flow rate, the heat exchanger compactness, the rows arrangement, the tube diameter, the transverse pitch, the total number of tubes, the number of rows and the air velocity.Simulations have shown that the heat exchanger performance could be improved essentially throughout the design and manufacturing process by modifying the different geometrical parameters and filling certain conditions.