一种替代CFC-12、HFC-134a新型的绿色制冷剂-GFL-12

介绍了CFC-12在家用电冰箱和汽车空调中的使用状况及HFC-134a替代CFC-12后工程技术上所出现的问题,阐述了选择GFL-12替代CFC-12及HFC-134a制冷剂的可能性,并对GFL-12、CFC-12及HFC-134a制冷剂在同一工况下,对型号为BCD-172和BCD-201电冰箱的性能进行了对比试验.     

日本新一代氢氟醚制冷剂的研究

本文介绍了日本政府组织的有关“新-代氢氟醚制冷剂研究开发”国家项目的进展和成果，HFE-245mc和HFE-143m最终被分别认为有望成为高温热泵工质CFC-114和冰箱、汽车空调工质CFC-12、HFC-134a的替代物。但迄今尚未找到替代HCFC-22的氢氟醚物质。原拟用于替代CFC-ll和HCFC-123的HFE-347mmy和HFE-347mcc，由于其制冷性能较差，最终也已基本被排除。     

替代R502的近共沸混合制冷剂R404A

R502是由HCFC-22和CFC-115组成的共沸混合制冷剂。现广泛应用于商用低温冷柜中。鉴于保护臭氧层及国际上对CFCs的禁用,R502因其中含有CFC-115而被淘汰。为此,务必寻求性能与R502相近的对臭氧层无害的新制冷工质。由HFC-125/HFC-143a及HFC134a(44/52/4 wt.％)组成的三元近共沸混合工质是R502的优先替代物。 本文对R404A的物理性质、制冷量、制冷系统和压缩机排气温度与R502进行比较,还对R404A的泄漏性和润滑油等多方面进行了讨论。     

近共沸混合工质HFC—152a／HCFC—22冰箱的研究

本文通过理论分析,选择国内已有产品供应的、对臭氧层破坏和温室效应均在许可范围内的制冷剂组成的近共沸混合物HFC-152a/HCFC-22的替代物。基本物性测定表明在HFC-152a中加入少量HCFC-22后,不仅使容积制冷量q_v增加,而且使HFC-152a的可燃性得到有效抑制。经过三批九台冰箱的数十次试验,确定了合适的配比、充灌量和冰箱的结构。采用HFC-152a/HCFC-22的冰箱型式试验全部项目国家标准GB8059.2-87。主要热工性能达到或优于原机水平,符合轻工部A级标准。这一替代技术对冰箱结构影响小,可在八·五期间形成生产能力。     

HCFC-141b/HFC-134a气体水合物蓄冷特性试验研究

水合物蓄冷技术是一种新型、极具潜力的蓄冷技术。通过试验研究混合制冷剂水合物HCFC-141b/HFC-134a的蓄放冷过程。试验结果表明:不同配比、不同载冷剂温度及加入表面活性剂对HCFC-141b/HFC-134a气体水合物蓄冷速率和蓄冷密度有不同的增益或抑制作用。     

限期停止使用CFC-12汽车空调

国家环境总局和国家机械工业局于日前联合发出《关于中国汽车行业新车生产限期停止使用 CFC- 12汽车空调的通知》,要求各汽车制造厂及汽车空调器生产厂必须抓紧对 CFC- 12空调器的改造 ,尽快转为 HFC- 134a汽车空调器。从 2 0 0 2年 1月 1日起 ,所有生产的汽车必须停止装配 CFC- 12空调器。并委托中国汽车产品认证委员会自 2 0 0 2年 1月 1日起 ,只有符合相关标准的 HFC- 134a空调器才能发给认证证书和标志。限期停止使用CFC-12汽车空调@王艮     

一种新型汽车空调制冷剂CMR-05

介绍了一种新型的用于汽车空调的混合制冷剂(CMR-05).介绍了CMR-05的物理性质,分析了CMR-05作为汽车空调替代制冷剂的可能性.对CMR-05进行了理论循环计算,并与R12和R134ad的理论循环的计算结果进行了对比.通过汽车空调测试证明了CMR-05具有较好的制冷性能,分析了CMR-05存在的问题,得出CMR-05可以作为R12与R134a的替代制冷剂.     

HFC-134a的热物理性质

这份资料是为HFC-134a的未来用户(承包人、制造商、或者维护人员)而编写。 它包括了现有的有关这个新制冷剂的数据,当我们研制出新的资料数据时,会随时补充。 这些数据将HFC-134a与CFC-12作一比较,供用户在换用新制冷剂时,对其设备及制冷系统部件进行研制改进。     

非共沸混合工质HFC-32/HFC-125/HFC-134a在家用空调器中替代HCFC-22的实验研究

本文以春兰公司生产的窗式空调器KC-20A为实验样机,没有对原装置作改动情况下在风管热平衡空调器性能测试试验台进行了三元非共沸混合工质HFC-32/HFC-125/HFC-134a(23/25/52 Wt％)的充注对比实验。实验结果表明在合适的充注量和毛细管长度下,混合工质的性能接近于原HCFC-22的,制冷量为HCFC-22的96％,能效比是它的94.6％。     

全无氟冰箱的开发研究

本文介绍了青岛电冰箱总厂“全无氟”电冰箱的开发研究情况,描述了以 BCD-220电冰箱为例,采用 HFC-141b 替代 CFC-11作发泡剂、HFC-134a 替代 CFC-12作制冷剂后的测试试验结果,并与替代前作了对比分析,同时指出了“全无氟”冰箱开发及生产中应注意的问题。试验结果表明,替代后各项性能指标均能符合我国国标要求,耗电量值与原来水平相当,比目前国内外公布结果要好,经过改造和增加部分设备、仪器,即可进行“全无氟”冰箱的批量生产。     

Temperature-dependent electron capture detector response to common alternative fluorocarbons

The relative electron capture detector (ECD) response to alternative fluorocarbons (AFCs) using gas chromatography are found to be at least 1 order of magnitude lower than that for CFC-12. Detection limits for the chlorofluorocarbons CFC-12, HCFC-22, HCFC-123, and HCFC-124 are found to be 2.5, 90, 30, and 90 pg, respectively. Those for the hydrofluorocarbons are significantly poorer; 14 and 45 ng for HFC-125 and HFC-134a, respectively. HFC-152a was not detected using ECD. Since atmospheric concentrations of these compounds are in the low part-per-trillion level, GC-ECD is apparently not sensitive enough to be used for AFC analysis without substantial preconcentration. Two columns are evaluated for the AFC separation. The Poraplot Q WPLOT column showed good separation ability, though column bleed limits detection performance. A Carboxen 1004 packed column exhibits much lower interference. But separations are time consuming and peak broadening adversely affects limits of detection. Mechanisms for the ECD response are proposed based on thermodynamics and temperature-dependent ECD responses. CFC-12, HCFC-123, and HFC-125 apparently undergo ion-forming dissociative electron capture. The electron capture process for HCFC-22 and HFC-134a appear to form molecular ions. Both mechanisms appear to be operative for HCFC-124 electron capture. Dissociative electron capture rate constants for HCFC-123, HCFC-124, and HFC-125 are estimated to be 3.5 × 10(-)(10), 1.0 × 10(-)(10), and 5.6 × 10(-)(13) cm(3) s(-)(1), respectively at 300 °C.     

Potentially acceptable substitutes for the chlorofluorocarbons: properties and performance features of HFC-134a,HCFC-123, and HCFC-141b

Potentially acceptable substitutes are known for CFC-11 and CFC-12-the most important Chlorofluorocarbons. HFC-134a could replace CFC-12 in airconditioning and refrigeration and both HCFC-123 and HCFC-141b show promise as CFC-11 substitutes. The replacement molecules all have significantly reduced greenhouse and ozone depletion potentials compared to their fully halogenated counterparts. HCFC-123 is theoretically a less efficient blowing agent than CFC-11, but 141b is more efficient. Results from experimental foaming tests confirm these relationships and show that initial insulating values are slightly lower for 141b and 123 than 11. Both substitutes are nonflammable liquids. Based on its physical properties, HFC-134a is an excellent replacement candidate for CFC-12. In addition, it is more thermally stable than CFC-12. A new family of HFC-134a compatible lubricant oils will be required. The estimated coefficient of performance (COP) of 134a is 96–98% that of CFC-12. Subacute toxicity tests show HFC-134a to have a low order of toxicity. HCFC-123 reveals no serious side effects at a concentration of 0.1% in subchronic tests and the inhalation toxicity of 141b is lower than that of CFC-11 based on a 6-h exposure. Chronic tests on all the new candidates will have to be completed for large-scale commercial use. Allied-Signal is conducting process development at a highly accelerated pace, and we plan to begin commercialization of substitutes within 5 years.Invited paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Equations of State for Technical Applications. III. Results for Polar Fluids

New functional forms have been developed for multiparameter equations of state for non- and weakly polar fluids and for polar fluids. The resulting functional forms, which were established with an optimization algorithm which considers data sets for different fluids simultaneously, are suitable as a basis for equations of state for a broad variety of fluids. The functional forms were designed to fulfil typical demands of advanced technical application with regard to the achieved accuracy. They are numerically very stable and their substance-specific coefficients can easily be fitted to restricted data sets. In this way, a fast extension of the group of fluids for which accurate empirical equations of state are available is now possible. This article deals with the results found for the polar fluids CFC-11 (trichlorofluoromethane), CFC-12 (dichlorodifluoromethane), HCFC-22 (chlorodifluoromethane), HFC-32 (difluoromethane), CFC-113 (1,1,2-trichlorotrifluoroethane), HCFC-123 (2,2-dichloro-1,1,1-trifluoroethane), HFC-125 (pentafluoroethane), HFC-134a (1,1,1,2-tetrafluoroethane), HFC-143a (1,1,1-trifluoroethane), HFC-152a (1,1-difluoroethane), carbon dioxide, and ammonia. The substance-specific parameters of the new equations of state are given as well as statistical and graphical comparisons with experimental data. General features of the new class of equations of state such as their extrapolation behavior or their numerical stability and results for non- and weakly polar fluids have been discussed in preceding articles.     

Prediction of the Vapor Pressure of Environmentally Acceptable Halocarbons1

The vapor pressure and its dependence on temperature of halocarbons for 0.002< p _R<1 have been analyzed in terms of universal behavior. Results for CFC-114, HCFC-123, HCFC-141b, HCFC-142b, HCFC-143a, HFC-23, HFC-32, HFC-134, HFC-125, HFC-134a, and HFC-152a for reduced temperatures between 0.55 and 1.0 show that the reduced vapor pressure can be expressed as a function of 1–T _R by a Padé approximant. Deviations of the correlated data from the universal function do not amount to more than ±0.06 MPa, with an average deviation of 0.025 MPa. Predictions of the saturation vapor pressures of HCFC-124, HCFC-225ca, and HCFC-225cb, which are the systems used to test the capability of this scheme, agree within 0.025 MPa, that is, within the accuracy of the corresponding states correlation. However, for HFC-236ea, the deviations are as large as –0.07 MPa. The present scheme can be used to calculate the Pitzer acentric factor, and an average value of =0.269±0.015 is obtained for all the fluids.     

Equations of State for Technical Applications. I. Simultaneously Optimized Functional Forms for Nonpolar and Polar Fluids

New functional forms for multiparameter equations of state have been developed for non- and weakly polar fluids and for polar fluids. The resulting functional forms, which were established with an optimization algorithm which considers data sets for different fluids simultaneously, are suitable as a basis for equations of state for a broad variety of fluids. With regard to the achieved accuracy, the functional forms were designed to fulfill typical demands of advanced technical application. They are numerically very stable, and their substance-specific coefficients can easily be fitted to restricted data sets. In this way, a fast extension of the group of fluids for which accurate empirical equations of state are available becomes possible. This article deals with characteristic features of the new class of simultaneously optimized equations of state. Shortcomings of existing multiparameter equations of state widely used in technical applications are briefly discussed, and demands on the new class of equations of state are formulated. Substance specific parameters and detailed comparisons are given in subsequent articles for the non- and weakly polar fluids (methane, ethane, propane, isobutane, n-butane, n-pentane, n-hexane, n-heptane, n-octane, argon, oxygen, nitrogen, ethylene, cyclohexane, and sulfur hexafluoride) and for the polar fluids (trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), chlorodifluoromethane (HCFC-22), difluoromethane (HFC-32), 1,1,2-trichlorotrifluoroethane (CFC-113), 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), pentafluoroethane (HFC-125), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), carbon dioxide, and ammonia) considered to date.     

Commercial refrigeration and CFCs

Copeland Corporation acknowledges the contribution of CFCs to the depletion of the stratospheric ozone layer. Copeland endorse the view that CFCs should be completely phased out by the year 2000 for new refrigerant applications and that the time schedule for phase out proposed in the Montreal Protocol should be accelerated. Copeland is taking a three-stage approach to the CFC problem, concentrating on the elimination of CFC-12 and CFC-502 and substituting HCFC-22 prior to the commercial availability of alternative refrigerants. The stages are as follows. (1) Eliminate CFC-12 by providing compressors which use HCFF-22 (down to -10°F) and CFC-402. (2) Modification of existing compressors to use HCFC-22 for applications down to -40°F evaporating temperature. This can be achieved by additional air-cooling on small compressors, demand cooling for large, single compressor units, or staging for multiple compressor applications. (3) Development of compressors for new refrigerants. The problems here include the high compression ratios required by HFC-134a, which result in a major loss in capacity compared to reciprocating compressors at medium and low temperatures. HFC-125 has a low critical temperature which limits its application and efficiency in high condensing temperature applications. Lubricating oils used with HFC-134a have a detrimental effect on some motor insulation materials and polymers; wear is also higher. Scroll compressor technology appears to have several advantages over reciprocating compressors in overcoming these problems in the long term.     

Experimental investigation on the performance and global environmental impact of a refrigeration system retrofitted with alternative refrigerants

This paper presents an experimental investigation of the drop-in process for HCFC-22 in a 5-ton refrigeration system. The original refrigerant was replaced by alternative halogenated refrigerants such as HFC-438A, HFC-404A, HFC-410A and HFC-32, as well as hydrocarbons HC-290 and HC-1270. The experimental facility was composed basically of a semi-hermetic reciprocating compressor, tube in tube heat exchangers and an electronic expansion valve. The tests were performed by just replacing the refrigerant, without changing any components, typically as in a drop-in process. The main parameters were varied to verify the range and performance of each refrigerant and then compared to the HCFC-22. Results showed that the natural refrigerants presented the best coefficient of performance and that results for HFCs, excepting the HFC-32, remained below those of HCFC-22. Regarding the environmental impact, using the parameter TEWI, the best results were reached with hydrocarbons; meanwhile, the refrigerant HFC-404A presented the highest environmental impact.     

Measurement of Speed of Sound with a Spherical Resonator: HCFC-22, HFC-152a, HFC-143a, and Propane

A spherical resonator and acoustic signal measurement apparatus have been designed and developed for measuring the speed of sound in the gaseous phase. The inner radius of the spherical resonator, being about 6.177 cm, was determined by measuring the speed of sound in gaseous argon at temperatures between 293 and 323 K and at pressures up to 200 kPa. Measurements of the speed of sound in four halogenated hydrocarbons are presented, the compounds are chlorodifluoromethane (CHClF₂ or HCFC-22), 1,1-difluoroethane (CH₃CHF₂ or HFC-152a), 1,1,1-trifluoroethane (CH₃CF₃ or HFC-143a), and propane (CH₃CH₂CH₃ or HC-290). Ideal-gas heat capacities and acoustic virial coefficients were directly deduced from the present data. The results were compared with those from other studies. In this work, the experimental uncertainties in temperature, pressure, and speed of sound are estimated to be less than ±14 mK, ±2.0 kPa, and ±0.0037%, respectively. In addition, equations for the ideal-gas isobaric specific heat capacity for HFC-152a, HFC-143a, and propane are proposed, which are applicable in temperature ranges 240 to 400 K for HFC-152a, 250 to 400 K for HFC-143a, 225 to 375 K for propane. The purities for each of the samples of HCFC-22, HFC-152a, HFC-143a, and propane are better than 99.95 mass%.     

Compressor technologies for low temperature applications of R-22

Substitutes for the commonly used refrigerants CFC-12 and CFC-502 are not commercially available. HCFC-22 is not suitable for low temperature applications because of the high discharge temperature caused by high compression ratios. Staged compression and liquid injection are two approaches to prevent compressor overheating in HCFC-22 low temperature applications. This paper describes the above approaches and their efficiency as compared to conventional applications.