空调系统制冷剂标定

为使空调系统获得最大或最优制冷性能,需要对空调系统制冷剂充注量进行标定,使空调系统在最佳充注量下发挥最佳性能。     

这辆汽车为何冷气不足

一辆金杯6480客车冷气不足,送本厂修理. 检修时,笔者先启动空调试验:手摸压缩机回气管,感觉很凉,再用压力表检测高、低压管路制冷剂压力,压力表指示值在正常范围内,说明制冷剂充注合适,空调系统运作基本正常.看来冷气不足只能是由鼓风机送风量不足,导致车内空气循环不畅,造成热交换不足所致.     

空调系统制冷剂过量造成的故障

故障现象:一辆猎豹指挥车给空调系统充注制冷剂后,开启空调时,压缩机电磁离合器时吸时不吸,怠速忽高忽低(800转分～1100转/分),制冷效果很差但风扇运转正常。故障检查:检测压缩机电磁离合器线路的电压正常,判定不是电路故障。把多用测量表(歧管压力计)接入空调系统的高、低压端口进行测量,高、低压端的压力都不正常,并随怠速变化压力忽高忽低,在贮液罐观察镜中也看不到气泡。后经询问驾驶员得知,充注制冷剂前并无此现象,据此怀疑制冷剂充注过多。故障排除:适当吸出一部分制冷剂后,发动机转速变化时在观察镜中能看到少量气泡,加速至1700转/分…     

汽车空调制冷剂的充注

对于因修理或更换零部件而放空后的汽车空调制冷系统,在完成维修作业后要重新充注制冷剂.制冷剂的充注包括抽真空、检漏、从高压侧充注液态制冷剂及从低压侧充注气态制冷剂、检查制冷剂充注量等基本作业.     

汽车空调制冷剂的充注

充注制冷剂工具1、真空泵(容量必须超过2.67KPa 18L/min)。2、歧管压力表:空调装置维修使用最普遍的工具,具有四种功能(是高压表和低压表的组合,装在一个表座上,表座的两端各有一个手动阀门,下部有三个通路接口,见图2)。3、制冷剂注入阀(充注的制冷剂为小罐时,需注入阀)。4、制冷剂计量工具(充注的制冷剂为瓶时,需计量工具)。5、捡漏仪(分电子捡漏仪和卤素捡漏灯两种)。     

轿车装配线上充灌制冷剂的新工艺及设备（上）

本文对轿车空调在线充灌制冷剂的新旧工艺对比，介绍了北京吉汽车有限公司采用的新工艺。     

燃料电池汽车空调系统制冷性能设计研究

通过对燃料电池车空调系统实验数据分析,着重研究电动压缩机的转速和制冷剂的充注量对空调制冷性能的影响,找出燃料电池汽车中影响空调系统制冷性能的关键因素,为后续空调系统的更好应用指明了方向.     

汽车空调控冷剂充注量及其检查

汽车空调制冷剂充注量对制冷系统工作性能的影响；加注和补充制冷剂时如何检查和确定制冷剂的充注量。     

制冷剂回收机在汽车维修中的重要性

1、制冷剂回收机的功能特点在汽车维修作业时,经常要用到制冷剂回收机,俗称冷媒充注机、冷媒回收机或加氟机。其实,如果从功能上来理解,制冷剂回收机可以分为单充注机、单回收机和回收充注机。单充注机,主要组成部分为真空泵、充注管、高低压表及接头,它只能完成充注制冷剂的功能。     

红旗世纪星空调不工作

行驶里程:68000km。 故障现象:空调压缩机不工作。 故障诊断:对于空调系统的检查一般遵循三步骤:①制冷剂;②线路;③元件的逐步排查。 因此,先用R134a充注     

二甲醚用作汽车空调制冷剂的实验研究

根据二甲醚的热物理性质对二甲醚的制冷循环性能进行了分析,并在R134 a汽车空调系统上对二甲醚的制冷性能进行了测试。结果表明:由于二甲醚的气相和液相黏度都比较小,使用二甲醚作为制冷剂可以减小系统的阻力,有利于系统制冷性能的提高。二甲醚可以直接灌注式替代R134 a,但会造成蒸发器出口过热度降低,需对膨胀阀弹簧预紧力进行调整,才能充分发挥二甲醚的制冷性能。     

客车后桥壳铸件工艺数值模拟及优化设计

介绍了CAE技术在客车后桥壳铸件模具设计中的应用,实施了以华铸CAE/Inte CAST软件系统对铸件的充型过程、凝固过程数值模拟分析,预测了铸件缩孔、缩松等缺陷,实现了铸件工艺模具的优化设计。     

Analysis of the performance of the evaporator of automotive air conditioning system

The purpose of this research was to establish a theoretical model for the evaporator of automotive air conditioning system and conducting simulations to evaluate the effect of operation parameters, environmental conditions, and design parameters on the performance of evaporator. An automotive air conditioning system primarily consists of four components: the compressor, the condenser, the refrigerant controller, and the evaporator. The refrigerant flow in the evaporator can be divided into two regions: the evaporating region and the superheat region. The refrigerant in the first region is a two-phase flow, while the refrigerant in the latter region is in the state of superheated vapor. The air flowing through the interior of the evaporator can also be divided into two zones: the unsaturated zone and the saturated zone. Water vapor is condensed in the saturated zone while in the unsaturated zone, no water condenses. Because the refrigerant flow and the airflow are perpendicular to each other, the distribution of refrigerant in the evaporating region and the superheat region does not coincide with the distribution of air in the unsaturated zone and the saturated zone. This study examines the effects of different design parameters, environmental conditions and operating parameters on the cooling capacity and superheat of an air conditioning system. Design parameters include the length of the refrigerant channel, the length of the air channel, and the thickness of the fins. Environmental conditions include the air inlet temperature and absolute humidity. Operation conditions include the refrigerant inlet enthalpy, inlet air flow rate, and refrigerant mass flow rate. Results of simulation demonstrated that fins with 50 micron meters width has the greatest cooling capacity for identical outer dimensions; thicker or thinner fins only decreased cooling capacity. Under different outer dimensions, longer refrigerant tubes and air channels created a greater cooling capacity. However, the increase in cooling capacity becomes less and less if the refrigerant flow was fixed because the heat transfer capability of the gaseous refrigerant was limited. In this study, an increase of 19% in cooling capacity can be reached as the length of refrigerant channels was increased, and the increased length of the air channels can promote the cooling capacity by 22%. Besides, it was found in this study that a decrease in the refrigerant inlet enthalpy, the inlet air flow rate, the air inlet temperature, and the inlet absolute humidity, or an increase in the refrigerant mass flow rate, would extend the superheat region and decrease the refrigerant’s superheat. It was also found that the cooling capacity of air conditioners is extremely sensitive to changes in the refrigerant mass flow rate and the inlet enthalpy, and variations more than 50% were found in the operating ranges examined in this study. However, changes in the inlet temperature, absolute humidity, and inlet air flow rate only resulted in variations between 10% and 20% in the examined ranges of conditions. Finally, a correlation among these variables and the simulated cooling capacity was obtained in this study, enabling the relevant researchers to evaluate automotive air conditioning performance under different environmental conditions and operation parameters more easily.     

THRO1a制冷剂在汽车空调中替代R12的研究

THRO1a制冷剂是一种绿色环保型产品，从制冷剂性质要求方面分析了THRO1a替代R12的可行性。通过对比试验可看出，在不对汽车空调系统做任何改动的情况下，用THRO1a替代R12，制冷能力与原R12系统相当。实车替代对比试验证明，THRO1a替代R12后，在制冷效果方面基本相同或略有改善。     

制冷剂/压缩机油与PA6的相容性研究

采用红外光谱分析和热重分析研究了不同规格PA6(聚酰胺6或尼龙6)的区别,不同规格PA6的红外谱图有细微区别,PA6在350℃之前的热失重量不同,可见其增塑剂等小分子的含量不同,这不但影响PA6的耐热老化性能,还会明显影响PA6的挤出工艺和使用性能。通过PA6在制冷剂、压缩机油、制冷剂/压缩机油等介质中的热老化测试和测试后试样的热重分析,对比了不同PA6的体积变化和热失重曲线,结果表明不同规格的PA6与制冷剂/压缩机油等介质的相容性不同。同一规格的PA6在不同的制冷剂/压缩机油中体积变化不同,R1234yf/POE(2,3,3,3-四氟丙烯/多元醇脂)体系中体积变化率最小,并且在不同的制冷剂/压缩机油共混体系对PA6性能的影响中制冷剂起决定性作用。     

R1234yf与R134a空调性能实验研究对比分析

为了实现制冷剂环境友好性,本文基于R1234yf与R134a不同的热物性参数基础上,在整车上进行R1234yf与R134a不同制冷剂系统的制冷性能及系统差异性的对比研究。分析R1234yf制冷剂的可替代性,进一步采取有效措施提高其制冷性能。     

Experimental study on performance of automotive air conditioning system using R-152a refrigerant

Recently, as climate changes have manifested worldwide, every country is making efforts to prevent ozone depletion and global warming. In the automotive industry, R-134a refrigerant is widely used in air conditioning systems because it has zero ozone depletion potential (ODP). Unfortunately, its global warming potential (GWP) is high. Therefore, alternative refrigerants are needed as a replacement for R-134a. R-152a is considered to be one of the better alternative refrigerants due to zero ODP and low GWP. In this paper, the performance of an automotive air conditioning system using R-134a and one using R-152a are compared experimentally at the bench level. The experimental apparatus simulated a real automotive air conditioning system consisting of a cabin and engine room structure. The cooling capacity, condensing capacity, coefficient of performance (COP) and power consumption characteristics of the automotive air conditioning system are evaluated by changing the air velocity entering the condenser and the compressor rotation speed with the optimized refrigerant charge amount. Also, the performance of the R-152a system was investigated by changing the thermostatic expansion valve which is set of values. The results of this study show that the R-152a system is slightly better than the R-134a system, not only under driving conditions but also under idling condition. R-152a refrigerant thus shows promise as an alternative refrigerant to replace the current standard, R-134a, in automotive air conditioning systems.     

Performance of air conditioners with a gas-liquid separation condenser and one-tank laminated evaporator

In this study, a parallel flow condenser and laminated evaporator for an automotive air-conditioning system were modified to improve performance. Gas-liquid separation type condensers, in which the condenser and receiver drier are integrated, and one-tank laminated type evaporators were developed, and their performances were investigated experimentally using HFC-134a. Heat transfer characteristics in the condenser are examined by means of air temperature, air velocity entering the condenser and inlet pressure of the refrigerant; heat transfer characteristics in the evaporator are examined by means of air temperature, relative humidity, flow rate of air, outlet pressure of refrigerant and superheat. Pressure drops for both evaporator and condenser are also measured, and correlations for pressure drop are derived for the condenser and evaporator, respectively. Air velocity and mass flow rate of the refrigerant have a significant effect on the overall heat transfer coefficient, and flow pass is not significantly influenced by the cooling capacity of the condenser. The overall heat transfer coefficient of the evaporator increases as air flow rate, air temperature and relative humidity increases.     

基于拉格朗日松弛算法的自动驾驶公交调度优化研究

为了解决公交实际运营出现的调度方式单一、车辆配合度较差、串车等问题，降低公交运行中人为因素的影响，提高公交系统的运营效率，提出一种考虑乘客动态需求的调度模型，采用自动驾驶环境下的公交运营方式，结合站点实际乘客需求调配车辆，实现了公交车辆利用程度最大和乘客总体等待时间最小的多目标优化。提出的自动驾驶公交调度方法，获取了乘客个体的实时出行需求，同时实现了对车头时距的调控。在模型求解方面，选取拉格朗日松弛算法，最终获得了多目标优化问题的精确解。以北京公交300路快车作为实际案例进行分析，从公交实际运营数据中提取多项参数作为模型的输入，通过拉格朗日松弛算法的求解，得到自动驾驶条件下公交运行时刻表、乘客等待时间、公交承载量、站点上车乘客人数等多项运营指标。通过与公交实际运营状态的对比，论证了采用自动驾驶公交对于改善公交运营现状的可行性。最后将优化结果与公交实际数据进行了对比分析。结果表明：自动驾驶车辆投入公交运营，能够缓解串车问题，同一线路上公交车的载客量分布更为均衡，在同一断面的客流与车头时距的不均衡程度均有所降低；同时高峰时段发车数量减少了20%，公交车的平均承载量提高了21.7%，车辆平均间隔缩短了29.9%。     

美国混合动力城市客车示范运营

对美国的混合动力公交车示范运营及其节能环保效应进行了详细说明,为混合动力公交评价研究及我国混合动力公交车示范运营提供参考。随着重型混合动力技术的不断成熟及混合动力公交车成本的不断降低,混合动力公交车必将实现产业化,同时也将推动混合动力技术在轿车及其他车型上的运用。