汽车制造企业选择汽车空调制冷剂的原则

由于R134a的GWP值高达1430,限制其生产和使用已经是大势所趋。做为汽车空调制冷剂的主要采购和使用者,各汽车生产企业应尽早启动替代制冷剂的研究工作,并带动汽车空调生产厂家开展相应汽车空调系统的开发工作。本文详细介绍了汽车企业选择替代制冷剂应考虑的问题和基本原则,为各汽车生产企业选择替代制冷剂提供参考。     

车用空调R134a的发展现状与替代情况

R134a是HFC类物质,有较高的GWP值,根据《京都议定书》的要求这是需要淘汰的制冷剂。近来,国际社会对加快淘汰HFC的呼声日益高涨,欧美国家也颁布了法规来限制R134a在汽车空调中的使用。霍尼韦尔和杜邦等公司也研制出了新型的混合制冷剂。在中国,相应的研发工作也在进行,然而R134a在中国的消费却刚刚起步,预计未来的消费量会进一步增长。     

HFO-1234yf——新一代汽车空调制冷剂

介绍一种新型的应用于汽车空调系统的制冷剂HFO-1234yf。该制冷剂的典型特点是具有很低的全球变暖潜值（GWP=4）,且对于使用R134a制冷剂的汽车空调系统是一种潜在的且经济的直接替代方案。汽车空凋台架测试和实车性能试验的结果表明,直接充注HFO-1234yf制冷剂后,系统制冷量和COP与原R134a系统偏差均在5％左右。关于材料相容性方面,均可以直接使用POE和PAG润滑油,与橡胶的兼容性及软管密封性方面未见不良反应。危险性试验评估结果显示,该制冷剂为低毒性,且毒性低于R134a;实车泄漏试验测试表明,制冷剂泄漏时,遇到明火不会导致燃烧加剧。     

国际制造商加紧研发新型134a替代制冷剂

新的有关汽车空调系统制冷剞排放问题的欧洲指令2006／40规定，自2011年起禁止新型汽车使用GWP值超过150（如HFC-134a）的含氟气体（F-gases）；美国加利福尼亚州通过立法针对HFC134a的淘汰问题向企业施加压力。这些举措一方面导致制冷剂制造商Dupont和HoneyweU正全力研制新型替代制冷剂，另一方面也引起研究人员对co。的高度关注。Honeywell最近公布了有关“H—fluid”的研究成果：H—fluid是一种物性（沸点、临界温度、可燃性）与HFC-134a非常相似的共沸混合物，其GWP值约为10。     

基于氨工质的新型电动汽车空调系统性能研究

R134a制冷剂的GWP值较高,即将被淘汰,但采用何种制冷剂来替代R134a却还未明确。鉴于此,提出将氨这种天然制冷剂应用到电动汽车空调上,作为R134a的替代制冷剂,并对研究设计的氨工质电动汽车空调系统做了性能研究,研究表明:氨工质电动汽车空调系统理论COP随蒸发温度、过冷度的升高而增大,随冷凝温度、过热度的升高而降低;研究设计的氨工质电动汽车空调系统理论COP为4.09,与R1234yf理论COP相当,但经二次回路设计后氨比R1234yf安全可靠;相较于R152a,氨的GWP值更低,环保性更好;相较于CO2,氨的COP更高,节能性更好。     

低GWP制冷剂在冷冻冷藏行业的应用分析

随着环境问题的日益突出,冷冻冷藏行业制冷剂的应用也面临新的选择.本文主要介绍了在低GWP应用趋势下,适用于冷冻冷藏的多种低GWP制冷剂的应用情况.这些制冷剂可分别用于R134a和R404A制冷剂的替代.选择适应未来的制冷剂,需要从平衡性能(能力能效)、安全性(可燃性和毒性)和可持续性(GWP值限制)、商业化状态、全生命...     

三氟甲醚作为汽车空调制冷剂的性能研究

对三氟甲醚（HFE143a）用作汽车空调制冷剂的性能与现有汽车空调制冷剂R134a进行了对比。首先比较了三氟甲醚和R134a的基础热力性质,然后对三氟甲醚和R134a的汽车空调标准工况和变工况下制冷循环性能进行了详细的理论计算及分析。分析表明：三氟甲醚的制冷性能与R134a基本相似,而性能系数（COP）却优于R134a。因此,更具环保优势的三氟甲醚是一种理想的潜在汽车空调制冷剂。     

二甲醚作为汽车空调制冷剂的性能研究

本文对二甲醚（DME）用作汽车空调制冷剂的性能与现有汽车空调制冷剂R134a进行了对比。首先比较了二甲醚和R134a的基础热力性质，然后对二甲醚和R134a的汽车空调标准工况和变工况下制冷循环性能进行了详细的理论计算及分析。分析表明：二甲醚的制冷性能与R134a基本相似，而性能系数（COP）却优于R134a。因此，更具环保优势的二甲醚是一种理想的潜在的汽车空调制冷剂。     

新型制冷剂HFO-1234yf/R134a/DME的理论与试验研究

提出一种在汽车空调应用中替代R134a的新型制冷剂HFO-1234yf/R134a/DME。利用数据库REFPROP 9.0,通过自行编制的软件对该制冷剂的热力学性能和循环性能进行理论分析,并在电量热器制冷剂循环性能测试装置上,对R134a和HFO-234yf/R134a/DME进行试验研究。理论与试验研究发现,新型制冷剂的制冷量比R134a略小,循环性能系数(COP)也略低,而排气温度比R134a低12℃左右。该新型制冷剂具有替代R134a的潜在可行性。     

二甲醚作为汽车空调制冷剂的性能研究

对二甲醚（DME）在用作汽车空调制冷剂与现有R134a汽车空调制冷剂在基础热力性质、汽车空调标准工况和变工况下制冷循环性能进行了对比分析，并作理论计算。分析表明：二甲醚的制冷性能与R134a基本相似，而性能系数COP却优于R134a。因此，更具环保优势的二甲醚是一种理想的潜在的汽车空调制冷剂。     

新一代制冷剂HFO-1234yf的热物性模型

基于Peng-Robinson通用状态方程,采用基团贡献原理以及多项式拟合方法,建立了符合精度要求的新型LGWP制冷剂HFO-1234yf的热物性模型,并对模型进行了验证,利用数学软件对模型进行编程求解,得到了较为全面的HFO-1234yf制冷剂的热物性数据。将HFO-1234yf制冷剂与R134a及R417A制冷剂的热物性能进行了对比,结果显示HFO-1234yf的饱和蒸汽压力与定压比热容和R134a的表现相似,二者的饱和蒸气压均低于R417A,HFO-1234yf制冷剂与R134a和R417A相比,其饱和状态焓值较低,这将导致HFO-1234y系统运行时的性能系数不高。该模型能为HFO-1234yf制冷剂在汽车空调以及固定式空调制冷设备上的应用提供理论依据。     

Second law analysis of an automotive air conditioning system using HFO-1234yf,an environmentally friendly refrigerant

In this paper, a comparative study of the second law of thermodynamics is presented to determine the possibility of using HFO-1234yf, an environmentally friendly refrigerant, as a drop-in replacement of HFC-134a in automotive air conditioning system. For the thermodynamic analysis, a computer program is written to simulate the operating conditions of automobile air conditioning system. The thermodynamic properties of the refrigerants are extracted from the REFPROP 8.0 software. For calculating the coefficient of performance (COP), exergy destruction, exergy efficiency and entropy generation, computational models are used to evaluate the effects of different parameters on their changes. It is found that using HFO-1234yf as the air conditioning refrigerant leads to higher exergy efficiency compared to HFC-134a. Also, maximum entropy generation and exergy destruction occur in the compressor. The exergy destruction and entropy generation of the cycle components are less in the case of using HFO-1234yf refrigerant instead of HFC-134a.     

Analysis based on EU Regulation No 517/2014 of new HFC/HFO mixtures as alternatives of high GWP refrigerants in refrigeration and HVAC systems

The EU Regulation No 517/2014 is going to phase-out most of the refrigerants commonly used in refrigeration and air conditioning systems (R134a, R404A and R410A) because of their extended use and their high GWP values. There are very different options to replace them; however, no refrigerant has yet imposed. In this paper we review and analyze the different mixtures proposed by the AHRI as alternative refrigerants to those employed currently. These mixtures are composed by HFC refrigerants: R32, R125, R152a and R134a; and HFO refrigerants: R1234yf and R1234ze(E). It is concluded, from the theoretical analysis, that most of the new HFO/HFC mixtures perform under the HFC analyzed (although some experimental studies show the contrary) and, in most cases, do not meet the GWP restrictions approved by the European normative. Furthermore, some of the mixtures proposed would have problems due to their flammability.     

Comparative experimental study of low GWP alternative for R134a in a walk-in cold room

The environmental problems induced by the ongoing increase in the global worming potential (GWP) pose a significant interest among researchers. It was found that, the currently used refrigerants are with high GWP (National Refrigerants Inc., 2004), so that it becomes necessary to search for alternatives to these refrigerants that can properly operate on the same systems but with low GWP. Therefore a walk-in cold room working with vapor compression cycle is constructed and tested in this paper. The performance of R134a refrigerant with high GWP is compared to another low GWP refrigerant R1234ze in a trail to provide a solution of the problem of high GWP of refrigerants currently used in cold rooms. The results obtained in this study have shown that, the cooling capacity of R1234ze was lower than that of R134a by 2% to 13%. The lowest evaporating temperature that could be reached for R1234ze is −13 °C while the lowest temperature of R134a is −30 °C. Regarding the power consumption, R1234ze has lower power consumption than R134a by about 9% to 15% therefore it can be concluded that R 1234ze can be recommended to be used at high and medium evaporating temperature after carrying out the suitable modifications on the refrigeration cycle.     

新型制冷剂R1234ze(E)及其混合工质研究进展

低GWP值制冷剂R1234ze(E)(trans-1,3,3,3-tetrafluoropropene)作为R134a较为理想的替代品而被关注,但其单一成分的热力学性能和传输特性并不理想,在R1234ze(E)中混入R32成分可以有效改善其热力学性能。本文概述了低GWP值工质R1234ze(E)及其与R32混合物的热物性特征、传输特性及系统运行性能方面的研究现状,并与目前常用的制冷工质进行比较分析,指出R1234ze(E)与R32混合工质有望成为新型低GWP值替代工质。     

R1234yf热泵技术综述与潜力分析

为了满足逐步严苛的环保法规要求,R1234yf成为车用热泵制冷剂R134a的热门替代制冷剂之一。本文对R1234yf热泵技术的研究进行了综述与分析,其GWP<1,各方面性质均符合车用热泵系统的工作需求。在传热效果上,R1234yf的沸腾传热性能略优于R134a,且冷凝过程压降比R134a低5%～10%,优于R134a系统。在诸多R1234yf和R134a系统的仿真和实验研究中,R1234yf热泵性能略低于R134a,但可以通过优化零部件、强化补气、改善工况等方式使其与R134a十分接近甚至超越。R1234yf低压饱和压力比R134a高约15%,可以适配更高的压缩机转速,低温下制热性能比R134a更好,且较低的压缩机排气温度使系统工作更为稳定,强化补气的效果也优于R134a。因此,R1234yf在车用热泵中具有较好的工作性能和发展前景,可以作为R134a的替代制冷剂。     

Comparative performance analysis of the low GWP refrigerants HFO1234yf,HFO1234ze(E) and HC600a inside a roll-bond evaporator

This paper presents the comparative performance analysis of the low GWP refrigerants HFO1234yf, HFO1234ze(E) and HC600a inside a commercial roll-bond evaporator for household refrigerators. The vaporisation performances were evaluated at two evaporation temperatures, −15 and −20 °C, and different refrigerant mass flow rates and compared with those of the traditional refrigerant for domestic refrigeration HFC134a. The performance analysis was carried out using both thermocouples installed on the rear side of the roll-bond evaporator and an IR thermo-camera. Each of the low GWP refrigerants tested can be considered a good substitute for HFC134a, provided that the compressor displacement is adjusted to deliver the proper refrigerant mass flow rate. Only HFO1234yf exhibits performance similar to HFC134a at the same mass flow rate, therefore it can be considered a direct drop-in substitute for HFC134a.     

An experimental investigation of the energetic performances of HFO1234yf and its binary mixtures with HFC134a in a household refrigerator

In this paper, a comparative experimental analysis between HFC134a, HFO1234yf and a refrigerant mixture of HFC134a/HFO1234yf (10/90% weight) implemented in a domestic refrigerator is introduced. Adding 10% of HFC134a to HFO1234yf, the mixture becomes non-flammable with GWP still less than 150. The experimental tests have been conducted under sub-tropical conditions in accordance with the UNI-EN-ISO15502 standard. Two kinds of tests have been shown: pull down and 1-day energy consumption. The results show that HFC134a/HFO1234yf (10/90% weight) is the best drop-in refrigerant fluid for HFC134a in the domestic refrigerator used for the experimental tests. The refrigerant mixture has the closest behaviour to that of HFC134a in terms of temperatures and pressures. Furthermore, the cycle working with the optimal charge of the mixture shows an energy saving of 16 and 14% with respect to HFC134a and HFO1234yf, respectively.     

R1234yf as a substitute of R134a in automotive air conditioning. Solubility measurements in two commercial PAG oils

Starting from January 1st 2011, as stated by the Directive 2006/40/EC, fluorinated greenhouse gases with a global warming potential (GWP) higher than 150 can not be used in automotive applications any more. For this reason, 1,1,1,2-tetrafluoroethane (R134a), commonly used for these applications, will be abandoned and substituted by refrigerants with lower GWP. In recent times, a new fluid, 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) has been proposed as an interesting alternative, since it has a very low GWP and thermodynamic properties very similar to R134a. At the moment, only few data can be found on the thermodynamic properties of this new refrigerant and, in particular, its behaviour in solution with commonly used compressor lubricants is still to be evaluated. Here, solubility experimental data of R1234yf in a Polyalkylene Glycol (PAG) and in a specifically modified Double-Capped PAG (DC-PAG) commercial lubricants are measured with a static synthetic method at isothermal conditions, in the temperature range between 258 K and 338 K.