汽车散热器试验研究及性能分析

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重庆大学硕士学位论文
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英文摘要
ABSTRACT
As an important part of engine cooling system, the main function of automobile radiator is to release heat that absorbed from the engine nacelle by flat pipe and fin. It can not only make the cooling system maintain effective cycle but also ensure the normal work of the automobile engine. A high precision property test bed which was used to measure thermal dissipation and pressure drop of automobile radiator was designed on the basis of JB/T 8577-2005 and JISD1614-2000. As main measurement test, the air side is to use enthalpy difference method to calculate the thermal dissipation capacity. A sampling device was designed to measure the inlet air temperature; for the duct system, the measurement accuracy and measuring range are improved by using the venturi meter and multiple throat diameter flow meter. As auxiliary measure test, the medium side is to adopt specific heat method to measure the thermal dissipation capacity. A sampling device was designed with pressure standard connector and platinum resistance temperature standard connector to minish the effect of connecting line on the pressure drop, it is also convenient to measure temperature and pressure. It was proved that the experimental data was in good agreement with the normal data, the property test bed can be used in practical projects about automobile radiator. Considering the cooling medium and air are noncontact, the heat exchange happened only on the surface of the flat tubes and fins when automobile radiator is working, as long as an accurate mathematical model was established, the simulation can be carried out in the same way about radiators with different type of fins and flat tubes. In this article, a complete mathematical model about automotive radiator with louvered fin has been established on the basis of theoretical analysis and experimental data, the simulation program and simulation model have been compiled with matrix laboratory by an iterative algorithm that according to the gauge length to determine the discharge state of automotive radiator. It was proved that the simulation results were in good agreement with the test results, the heat exchange relative error of air side was less than3.5 %, the heat exchange relative error of medium side was less than3.1%, the pressure drop relative error of air side was less than7.2%, the pressure drop relative error of medium side was less than8.9%.
汽车散热器试验研究及性能分析
重庆大学硕士学位论文 （学术学位）
学生姓名：周 伟 指导教师：李夔宁 专 副教授
业：动力工程及工程热物理
学科门类：工 学
重庆大学动力工程学院
二 O 一三年五月
Performance Analysis and Experimental Research on Automobile Radiator
College of Power Engineering of Chongqing University, Chongqing, China May 2013
中文摘要
摘
要
汽车散热器作为发动机冷却系统的重要组成部分，主要作用是通过金属扁管 和翅片将冷却系统的循环介质在发动机舱吸收的热量传递给外部环境，以维持发 动机冷却系统有效循环，保证发动机的正常工作。 本文基于 JB/T 8577-2005、JIS D 1614-2000 等工业标准，研制了一种以测量散 热量和阻力压降为目的的高精度汽车散热器性能试验台。试验台主测为空气侧， 采用焓差法测定散热能力。试验台在空气侧设计增加了取样装置，以对进口空气 温度进行测量；试验台风道系统采用插入式多喉颈流量计和文丘里流量计组合的 方式对空气流量进行测量，不仅保证了测量精度和准确度，也提高了测量范围。 试验台辅测为介质侧，采用比热容法测定散热能力。试验台在介质侧设计增加了 一个有压力标准接头和铂电阻温度传感器标准接头的取样装置，以方便温度和压 力测量，减小连接管路对压力测量的影响。通过与出厂试验数据的对比可知：试 验数据准确有效、真实可靠，性能试验台能够应用于汽车散热器的工程实际。 考虑到汽车散热器工作时冷却介质和空气流动为非接触交叉流动，即通过扁 管和翅片外表面进行热交换，这样只要建立准确的数学模型，就可对不同扁管数 目，不同翅片形式散热器进行方法相同的仿真计算。本文以百叶窗翅片汽车散热 器为研究对象，以矩阵实验室为基础，编写根据汽车散热器计算长度确定出口状 态参数为迭代算法的性能仿真程序，对仿真程序进行可视化界面设计以完成散热 器传热和压降的仿真模型。通过仿真与试验结果对比可知：仿真结果与试验结果 在空气侧散热量相对误差<3.5%，介质侧散热量相对误差<3.1%，空气侧压降相对 误差<7.2%，介质侧压降相对误差<8.9%。 随着汽车产业的发展，散热装置在节省材料方面越来越被重视，要求汽车散 热器的开发设计是最优的可行方案 。本文通过矩阵实验室脚本文件编写散热器优 化程序，利用遗传算法以百叶窗开窗间距、百叶窗开窗角度，百叶窗翅片间距、 翅片厚度、扁管厚度、扁管管壁厚度为优化变量，对汽车散热器进行优化设计。 结果表明：在保证散热量和阻力压降满足设计要求情况下，相比于原散热器优化 后散热器耗材面积减少了 5.8％左右；在耗材面积一定和阻力压降满足设计要求情 况下，相比于原散热器优化后散热器的散热量提高了 4.2%左右。 关键词：汽车散热器，性能试验台，仿真模型，优化设计
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重庆大学硕士学位论文
With the development of automobile industry, the consume materials have to meet more strict demands, and an optimal feasible programme is required for automobile radiator. This article choose script file of matrix laboratory to knit optimization program and then the genetic algorithm is applied to optimize the louver pitch, shutter angle, fin pitch, fin thickness, flat tube thickness and flat tube wall thickness. It is proved that the optimized area is about less 5.8% than original area on the premise that thermal dissipation capacity and pressure drop meet the standard; the thermal dissipation capacity is about more 4.2% than original thermal dissipation on the premise that pressure drop meet the standard and certain radiate area. Keywords: automotive radiator, property test bed, simulation model, optimal design