汽车空调制冷剂与节能环保

CFCs制冷剂的禁用和各种替代制冷剂的出现,为汽车空调业提出了新的课题与挑战.阐述汽车空调系统使用的制冷剂与节能和环保的关系,对目前在研的制冷剂和可能的空调系统改造措施进行了综合分析,以期为汽车空调制造业提供参考.     

小型空调系统中碳氢化合物替代HCFC22的研究

以小型空调系统中HCFC22替代为应用背景，对碳氢化合物（HCs)及其混合物系进行了系统的理论循环分析，表明HC1270、HC290、HC1270／HC290、HC1270／HC600a、HC290／HC600a等具有在空调系统中替代HCFC22的潜力。对容积制冷量与HCFC22相近的HCs，在HCFC22窗机中进行了灌注式替代实验研究，结果表明，HCs的性能指标全面优于HCFC22。对不同工质间的公平实验比较、HCs应用中的安全性等问题进行了讨论。     

电冰箱制冷剂替化物（HFC134a）的研究与进展

一、前言由于CFC制冷剂的大量使用会导致大气同温层中臭氧的衰减,破坏生态环境,已起了人类的关注。1987年9月通过的《关于消耗臭氧层物质的蒙特利尔议定书》,确定了受控物质及控制过程。1990年6月在英国伦敦召开“蒙特利尔议定书缔约国第二次会议”,对《蒙特利尔议定书》又进行了修改,扩大受控物质范围,加快了控制过程。我国也于1991年6月1日向《蒙特利尔议定书》缔约国第三次会议递交了加入修改后的《蒙特利尔议定书》的文件。     

非共沸工质双压冷凝热泵热水器性能研究

提出一种双压冷凝梯级加热热泵热水器（DPS）系统新构型,采用碳氢非共沸工质作为制冷剂,可实现热水的连续梯级低损加热,采用黄金分割法对系统热力性能进行优化。结果表明,非共沸工质的DPS系统的热力学性能优于纯质的DPS系统和单级热泵系统,双压冷凝系统在最优中间水温时取得最大COP。名义工况下,采用R600/R601a(40/60)的DPS系统COP高达5.17,相对采用纯质的DPS系统和单级系统分别提高9.45%和14.25%。采用温度滑移合理的非共沸工质可显著减少损,改善冷凝器的热匹配特性,系统效率最高提升11.70%,名义工况下推荐R600/R601a(40/60)作为工质对。     

地源热泵系统制冷剂充注的实验研究

地源热泵机组制冷剂充注量的多少对机组的能效比影响较大.在建立的地源热泵系统实验台上,对制冷剂R22不同充注量的热泵机组的运行情况进行了测试.从外部水循环侧和内部制冷剂侧对热泵机组运行性能进行测量计算;同时进行了地源热泵系统运行的热力学分析;指出了制冷剂充注量对地源热泵系统运行性能的影响;最终得出了地源热泵机组制冷剂最佳充注量.研究结果为地源热泵系统的高效运行及能源的充分利用提供了理论和应用依据.     

环保型制冷剂R600a／R290的应用研究

以碳氢化合物R600a/R290 ,1∶1的配比直接灌注冰柜系统,比较两种工质的运行特性,研究了其充注量对冰柜性能的影响。R600a/R290作为氟利昂R12的替代工质,其循环性能与R12系统非常相似,实验结果为寻找环保型长期替代制冷剂提供了依据。     

两种主流制冷剂的VRV系统及施工浅析

正变制冷剂流量(VRV)系统是指在电力空调系统中,通过控制压缩机的制冷剂循环和进入室内换热器的制冷剂流量,适时地满足室内冷热负荷要求的高效率冷剂空调系统。其工作原理是:由控制系统采集室内舒适性参数、室外环境参数和表征制冷系统运行状况的状态参数,根据系统运行优化准则和人体舒适性准则,通过变频等手段调节压缩机输气量     

石墨烯纳米制冷剂核态池沸腾换热的实验研究

为分析单层石墨烯纳米片对核态池沸腾换热的影响机理,对基液为R141b、分散相为单层石墨烯纳米片的纳米制冷剂的核态池沸腾换热特征进行了测定,采用Hot Disk热物性分析仪和铂金板法分别测定了石墨烯纳米制冷剂的热导率和表面张力,采用接触角测量仪和扫描电子显微镜（SEM）观测了沸腾后加热表面的润湿性和形貌特征。实验中,单层石墨烯纳米片的质量百分含量（ω）为0.02%~0.50%,实验压力为一个标准大气压,热流密度为20~200 kW/m2。实验结果表明：单层石墨烯纳米片的加入,使制冷剂R141b的核态池沸腾换热得到强化;当ω=0.2%时,换热系数提高比例出现峰值,为57.7%。伴随ω的增加,石墨烯纳米制冷剂的热导率增大、表面张力减小,沸腾表面润湿性增强且微腔数先增后减,综合作用的结果导致存在一个最佳的单层石墨烯纳米片浓度（即ω=0.2%）使换热系数最高。     

混合制冷剂HFC152a/HFC125的电冰箱实验研究

对环保节能制冷剂——二元近共沸混合工质HFCl52a／HFC125在电冰箱上应用的制冷循环性能进行了详细的理论计算和分析，并且对该工质灌注式替代CFC12和HFC152a／HCFC22在不同配比和充灌量下的电冰箱主要制冷性能进行了实验研究。实验结果表明：在合适的配比和充灌量下电冰箱制冷性能指标满足国家标准要求。混合制冷剂HFC152a／HFC125优良的环保性能和冰箱制冷性能使它完全适合做新一代的冰箱制冷剂。     

一种可替代冷库中R22的新型节能环保制冷剂研究

实验研制一种可以替代HCFC-22的新型节能环保TJR02,该制冷剂的ODP值和GWP值要远低于CFC-22,具有滑移温度小、单位容积制冷量大、降温快、耗电少等优点,且无毒不燃。特别适合于冷库工况下的制冷循环,可以直接替代HCFC-22,达到节能环保的效果。     

New fluids as substitute refrigerants for R12

The aim of the present study is to suggest two new fluids as alternatives of R12 in a vapour compression cycle. These fluids are the methyl trifluoromethyl ether (E143a) and the hexafluorocyclopropane (C216), which belong to halogenated derivatives of dimethyl ether and cyclopropane, respectively. The two suggested fluids have low degree of toxicity and a quite short atmospheric life. They also have suitable boiling points and a relatively simple molecular structure.A method of estimation of the thermodynamic properties of E143a and C216 is presented. The theoretical performance of the new fluids are evaluated and compared to those of the R12.     

Thermodynamic analysis of R422 series refrigerants as alternative refrigerants to HCFC22 in a vapour compression refrigeration system

In the present study, the first and second law analysis of R422 series refrigerants (R422A, R422B, R422C and R422D) is presented as an alternative to HCFC22. A computational model, developed in engineering equation solver software, is employed for comparing the performance of these refrigerants in vapour compression refrigeration cycle. The thermodynamic properties of the R422 series refrigerants are computed using Refprop version 7.0. The parameters computed are volumetric cooling capacity (VCC), compressor discharge temperature, coefficient of performance (COP), exergetic efficiency and efficiency defects in system components. The results indicate that VCC, COP and exergetic efficiency for HCFC22 are higher in comparison with R422A, R422B, R422C and R422D. The efficiency defects in the condenser are largest followed by throttle valve, compressor and evaporator. Thus, the design improvement of condenser is of utmost importance to reduce the overall irreversibility and improve the system performance. Copyright © 2009 John Wiley & Sons, Ltd.     

Performance assessment of heat pumps using HFC125/HCs mixtures

The analysis of heat pump cycles with and without an internal heat exchanger (IHE) is carried out in the paper, in which HFC125/HCs binary mixtures are used as the alternative refrigerants. And the cycle performance under different operation conditions is also compared. The results show that when the mass fraction of HFC125 ranges from 10 to 20%, the coefficient of performance (COP) for HFC125/HC290 (M1) mixtures is 0.92 and 1.01% lower than that of HCFC22 and HFC134a, respectively. For HFC125/HC600 (M2) and HFC125/HC600a (M3) mixtures, the COPs are higher than those of HCFC22 at the mass fraction of HFC125 between 0 and 74.1%, 0 and 66.5% in the mixtures, respectively, and compared with HFC134a, the COPs and volumetric heating capacities are higher when the mass fraction of HFC125 is between 38.6 and 73.3%, and 30.8 and 66%, respectively. For HFC125/HC1270 (M4) mixtures, the COPs are always lower than those of HCFC22 and HFC134a. It is also found that the IHE has a slight effect on the COPs with varying the mass fraction of HFC125 in the binary mixtures. The results obtained can provide some useful guidelines for the choice of alternative refrigerants. Copyright © 2011 John Wiley & Sons, Ltd.     

A comparative study of water as a refrigerant with some current refrigerants

Water as a refrigerant (R718) is compared with some current natural (R717 and R290) and synthetic refrigerants (R134a, R12, R22, and R152a) regarding environmental issues including ozone depletion potential (ODP) and global warming potential (GWP), safety (toxicity and flammability), operating cost, refrigeration capacity and coefficient of performance (COP). A computer code simulating a simple vapour compression cycle was developed to calculate COPs, pressure ratios, outlet temperatures of the refrigerants from the compressor, and evaporator temperatures above which water theoretically yields better COPs than the other refrigerants investigated. The main difference of this study from other similar studies is that both evaporator temperature and condenser temperature are changed as changing parameters, but the temperature lift, which is the temperature difference between condenser and evaporator, are held constant and the irreversibility during the compression process is also taken into consideration by taking the isentropic efficiency different from 100%. It is found that for evaporator temperatures above 20°C and small temperature lift (5 K), R718 gives the highest COP assuming exactly the same cycle parameters. For medium temperature lifts (20–25 K), this evaporator temperature is above 35°C, whereas for even greater temperature lifts it decreases again. Furthermore, with increased values of polytropic efficiency, R718 can maintain higher COPs over other refrigerants, at lower evaporator temperatures. Copyright © 2005 John Wiley & Sons, Ltd.     

热泵系统用R744/HCs混合工质配比范围研究

针对现有碳氢类(HCs)工质进行综合分析比较,选定了一些适用于热泵系统的R744/HCs非共沸混合工质对。通过对选定的混合工质临界参数和温度滑移特性的进一步计算分析,确定了其适用的热泵循环,并建立了快速确定亚临界循环热泵系统用R744/HCs非共沸混合工质中R744质量配比范围的计算程序。结合热泵热水器的工况及高压侧压力的要求,利用计算程序确定了R744/R600、R744/R600a、R744/R601和R744/R601a的质量配比范围。     

Sustainability with prospective refrigerants

This paper first presents a brief historical summary of the recent past and current status of refrigerants, and then proceeds to suggest a simple Second Law‐based approach using the ideal vapor compression refrigeration cycle to estimate a refrigerant's performance potential. The resulting performance rankings are then supplemented by additional rankings of the exergy losses in the compressor and in the condenser. These methodologies are then applied to several refrigerants: three natural refrigerants (ammonia, propane, and isobutane), five conventional single‐component halocarbon refrigerants, two conventional blends of halocarbon refrigerants, and three newer refrigerants (fluorinated propene isomers). Generally speaking, the lower pressure refrigerants have better COP and lesser volumetric cooling capacity than the higher pressure refrigerants; whereas, the lower pressure refrigerants have higher penalty factor (measure of condenser exergy losses) than the higher pressure refrigerants. The analyses presented in this paper suggest that to minimize a refrigeration system's overall impact on the environment, the choice of refrigerant should not necessarily be based on a single criterion but rather should be chosen based on the particular application. Copyright © 2013 John Wiley & Sons, Ltd.     

Performance of some zeotropic mixtures as alternative refrigerants to R22 and R502

Many zeotropic refrigerant mixtures are being proposed as alternatives to CFCs and HFCFs refrigerants that are being phased out. The main advantage in the use of zeotropic mixtures is the possibility of reduction in entropy generation in the condenser and evaporator by matching the glides of refrigerant and heat transfer fluid. Glide matching is difficult with some zeotropic mixtures due to the nonlinear variation of enthalpy with temperature during phase change. Also, there is a distinct possibility of formation of pinch points with some mixtures, resulting in entropy generation. In this paper, the performance of four mixtures of R32, R134a, R125, R143a and R23 are studied as alternatives to R22 and R502 from thermodynamic as well as temperature pinch points of view. The results demonstrate the importance and the need for pinch point analysis in the evaluation of alternative zeotropic refrigerant mixtures. © 1998 John Wiley & Sons, Ltd.     

Research on non-flammable criteria on refrigerants

The two targets including the ratio of maximal composition RXM and the minimum for operating area SMI have been proposed for judging the flammability of the alternative to CFCs and HCFCs in air conditioner and refrigeration system. Analytical results in this paper illustrate that for different flammable refrigerants, the RXM and SMI are different and the relationship between different refrigerants are also different, which depends on the flammability of the refrigerant.     

二氧化碳/丙烷用于热泵系统循环性能分析

在热泵热水器名义工况条件下,对二氧化碳(R744)/丙烷(R290)自然混合工质与四种常见的热泵工质R22、R134a、R410A和R407C的亚临界循环性能进行了分析对比。结果表明:R744/R290的最优质量配比为21/79,系统的制热循环性能系数(COPh)比R22系统提高了10.46%、比R134a系统提高了22.67%、比R410A系统提高了11.93%、比R407C系统提高了9.52%;在10%~35%、0%~35%、10%~35%和10%~35%的R744质量配比内,R744/R290可分别实现对四种常见热泵工质的替代;在最优质量配比下,R744/R290系统的冷凝压力低于R410A系统,压比仅为3.271,排气温度为80.9℃。     

The testing and evaluation of trial refrigerants: Part 1. System description

This work is a contribution to the discovery and evaluation of new refrigerants. It has been stimulated by the uncertainty created by the Kyoto Protocol over the long‐term availability of the hydroflorocarbons (HFCs) and also by the need for more knowledge of HFC–oil pairings. An economical method for testing refrigerants in terms of coefficient of performance (COP) and evaporative behaviour in a lubricated system is described. Part 1 describes the equipment, its instrumentation and operating procedures. Part 2 discusses the system output for four test refrigerants: two single fluids R134a and R22 and two test non‐azeotropic blends each having a glide of around 9 K. Study of R22 was confined to evaporative behaviour. The ranking of refrigerants by COP and boiling length is given and the generality of use of these rankings is discussed. Copyright © 2000 John Wiley & Sons, Ltd.