CFC动态

HFC-245fa适宜作发泡剂美国AlliedSignal公司最近作的一项研究表明,HFC-245fa可作为一种性能优良的发泡剂使用。研究中将三种发泡剂HFcy245fa（CF3CHCFZH）,HCFC-14fo（CC12FCH3）和CFC-11（CC13F）进行了比较。结果显示,采用HFC-245fa的发泡材料的泡沫尺寸稳定性是最好的,泡沫材料的其它性能均优于HFC-141b。研究还表明,人们对于HFcy245fa的加工技术需要给于更多的关注并进行更多的研究。美国环保署批准替代HCFC的发泡剂美国环保署今年初正式批准使用轻质饱和烃替代HCFCS用于聚异氰酸酯和聚氨酯硬泡板的生产。环保署还…     

HFO-1336mzz(Z)在有机朗肯循环系统中的研究进展

有机朗肯循环(ORC)的工质选择对系统的效率和系统设计起着关键作用,以往使用的工质HFC-245fa因为GWP高达1030,无法满足国际社会的环保要求.本文比较了HFO-1336mzz(Z)与HFC-245fa的物性与系统性能,HFO-1336mzz(Z)有较高的临界温度和较低的临界压力,能够在较高的蒸发器温度下工作,...     

发泡剂替代物HFC 245fa介电系数的实验研究

我国制冷产品随着在国际市场上的份额不断扩大，需要满足严格的环境保护要求，其中一项就是采用对臭氧层无破坏作用的制冷剂与发泡剂，HFC-245fa不仅介电性能好而且温室气体排放量小，是非常好的发泡剂。主要对新型发泡剂HFC-245fa的介电系数进行了实验研究。通过对大量实验数据的拟合处理，得出了介电系数与温度、压力和温度、密度的关联式，为产品设计提供基本参考数据。     

霍尼韦尔Enovate-245fa发泡剂的性能与应用

随着蒙特利尔条约在相关国家的实施，CFC化合物已经逐步被淘汰．HCFC化合物也己在欧洲、美国、日本等一些国家实行了禁止和淘汰.我国是HCFC化合物生产和使用的大国，其逐步淘汰也已经提上了议程。霍尼韦尔公司很早就致力于HCFC-141b的替代工作，并为其OODP发泡剂产品HFC-245fa在不同的领域的应用都作了相应的研究。本文介绍了该公司HFC-245fa的一些基本性能及其在冰箱，喷涂和板材的应用情况。     

采用HFC245fa新制冷剂的离心式冷水机组

日本荏原（Ebara）公司近期开发成一种采用新型低压制冷剂HFC-245fa的离心式冷水机组。首台样机已经售予日本东北部的一家工厂。     

由五氟乙烷气相催化合成1-氯-3,3,3-三氟丙烯的方法

1-氯-3,3,3-三氟丙烯(HFO-1233zd)是一种重要的化工原料。本研究介绍一种由五氟乙烷(HFC-245fa)作为原料,有机或无机氯化物作为氯源,通过气相催化合成1-氯-3,3,3-三氟丙烯的方法。对催化剂活性组分、不同载体、种类氯源种类进行了研究。结果表明,245fa与CCl4在Cr/Al_2O_3催化剂的作用下,可以高效地生成1233zd。     

第四代液体发泡剂E-HCFO-1233zd

反式-1-氯-3,3,3-三氟丙烯(E-HCFO-1233zd)作为1,1,1,3,3-五氟丙烷(HFC-245fa)的理想替代品而被关注。介绍了第四代液体发泡剂E-HFO-1233zd的性能以及合成研究进展,并展望了开发应用前景。     

复叠式水水热泵的制冷剂筛选

结合我国现行制冷剂标准,按照环境相容性、安全性、热工循环性能原则进行了高温复叠式热泵循环的制冷剂筛选,对不同制冷剂组合进行了计算和分析。结果表明,高低温侧制冷剂可采用R245fa/R134a、R245fa/R420A、R245fa/R413A、R245ca/R420A等组合。若进一步考虑制冷剂获得的容易程度、经济性等因素时,可选择R245fa/R134a组合。     

复叠式水水热泵的制冷剂筛选

结合我国现行制冷剂标准,按照环境相容性、安全性、热工循环性能原则进行了高温复叠式热泵循环的制冷剂筛选,对不同制冷剂组合进行了计算和分析.结果表明,高低温侧制冷剂可采用R245fa/R134a、R245fa/R420A、R245fa/R413A、R245ca/R420A等组合.若进一步考虑制冷剂获得的容易程度、经济性等因素时,可选择R245fa/R134a组合.     

电子级六氟丙烷的制备及纯化研究进展

近年来电子级六氟丙烷以其优越的安全性、高效的刻蚀速率、良好的选择性,成为了新一代等离子体刻蚀气体。对六氟丙烷HFC-236fa及其同分异构体HFC-236ea进行了概述,并介绍其制备方法、工业级及电子级纯化方法的研究进展。     

The effect of blowing agent choice on energy use and global warming impact of a refrigerator

A study, comparing the effect of blowing agent selection on energy consumption and the life cycle climate performance (LCCP) of a typical European refrigerator is discussed. Energy consumption of prototype European-style refrigerators made with a foam formulation with HFC-245fa as the blowing agent was measured and compared with energy consumption of the same model as currently produced (using a foam with a pentane blend for the blowing agent). Results were used in a LCCP study, considering both direct and indirect climate impacts due to blowing agent emissions and energy consumption in manufacturing processes and over the life cycle of the refrigerator. An assumption is made that the refrigerator is built and used in the European market.     

第三代发泡剂HFC-245fa

介绍了 1 ,1 ,1 ,3,3 五氟丙烷 (HFC 2 4 5fa)的各种性质。HFC 2 4 5fa作为CFC 1 1和HCFC 1 4 1b的长期替代品 ,已成为第三代发泡剂     

Measurement of the dipole moments of seven partially fluorinated hydrocarbons with a radiofrequency reentrant cavity resonator

Equilibrium dipole moments of gaseous pentafluorodimethyl ether (HFE-125), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,2,2,3-pentafluoropropane (HFC-245ca), 1,1,1,2,2-pentafluoropropane (HFC-245fa), and 1,1,1,2,2,3,3,4-octafluorobutane (HFC-338mccq) were obtained from the resonance frequency of a reentrant cavity at temperatures between 250 and 373K. The electronic contributions to the polarization were determined for each fluid from liquid-phase optical index of refraction measurements at 297 K.     

HFC-245fa体系聚氨酯硬泡导热系数的改善

介绍了在冰箱、冰柜制冷行业中作为下一代有很大发展前景的HFC 2 4 5fa体系 ,以及如何改善HFC 2 4 5fa体系聚氨酯硬泡导热系数偏高的问题     

氟里昂发泡剂替代技术的新进展

介绍了各种氟里昂替代品的品种和特性 ,对CFC、HCFC、HFC和HC类发泡剂的特性进行了对比和讨论 ,认为HCFC 141b和HCFC 2 2 / 142b是替代CFC物质的过渡性替代发泡剂 ,环戊烷和HFC 2 4 5fa是最终长期替代CFC发泡剂的最有希望替代品。     

Experimental investigation on the thermal stability of some new zero ODP refrigerants

Five zero ODP (ozone depletion potential) hydro-fluorocarbon refrigerants (HFC-23, HFC-143a, HFC-227ea, HFC-236fa, HFC-245fa) were tested to define their maximum usable temperature and their thermal degradation threshold. Pyrolysis is detected (a) as a pressure change at constant temperature and volume; (b) as a departure of the vapour pressure curve of the heated fluid from that of the original substance. Visual inspection of the vessel walls and fluid chemical analysis complement the method. The minimum detectable degradation rate is believed to be less than 1% in 50 h. All the fluids exhibit a variable, but excellent thermal stability up to the following temperatures at which no decomposition was observable in 50–100 h: 425 °C for HFC-227ea, 400 °C for HFC-23 and HFC-236fa, 350 °C for HFC-143a and 300 °C for HFC-245fa. Clear degradation signs were observed at temperatures 25–50 °C higher. Most of the fluids heated up to their thermal stability threshold exhibited an induction period of 5–50 h in which no decomposition was detectable but after which an observable degradation started. For a given fluid such period decreases at increasing temperatures. The use of fluids in a cyclic process in which the working medium permanence at the top temperature is very brief could take advantage of this behaviour with a reduction in degradation rates or with an increase in the limiting temperature. The influence of the decomposition products on the functionality of a thermodynamic power cycle was investigated by means of an appropriate computer code. The working fluid was assumed to be a binary mixture with 1 to 3% concentration of a light decomposition product of the methane series. Chemical species such as CH₄ and CF4 with a critical temperature much lower than that of the base fluid strongly affect the cycle configuration. On the contrary species with critical temperatures closer to that of the base fluid such as CH₃F, CH₂F₂ or CHF₃ influence only marginally the cycle performance. In general a small concentration of decomposition products in the working medium is likely to be acceptable without noticeable drawbacks.

Résumé

Five zero ODP (ozone depletion potential) hydro-fluorocarbon refrigerants (HFC-23, HFC-143a, HFC-227ea, HFC-236fa, HFC-245fa) were tested to define their maximum usable temperature and their thermal degradation threshold. Pyrolysis is detected (a) as a pressure change at constant temperature and volume; (b) as a departure of the vapour pressure curve of the heated fluid from that of the original substance. Visual inspection of the vessel walls and fluid chemical analysis complement the method. The minimum detectable degradation rate is believed to be less than 1% in 50 h. All the fluids exhibit a variable, but excellent thermal stability up to the following temperatures at which no decomposition was observable in 50–100 h: 425 °C for HFC-227ea, 400 °C for HFC-23 and HFC-236fa, 350 °C for HFC-143a and 300 °C for HFC-245fa. Clear degradation signs were observed at temperatures 25–50 °C higher. Most of the fluids heated up to their thermal stability threshold exhibited an induction period of 5–50 h in which no decomposition was detectable but after which an observable degradation started. For a given fluid such period decreases at increasing temperatures. The use of fluids in a cyclic process in which the working medium permanence at the top temperature is very brief could take advantage of this behaviour with a reduction in degradation rates or with an increase in the limiting temperature. The influence of the decomposition products on the functionality of a thermodynamic power cycle was investigated by means of an appropriate computer code. The working fluid was assumed to be a binary mixture with 1 to 3% concentration of a light decomposition product of the methane series. Chemical species such as CH₄ and CF4 with a critical temperature much lower than that of the base fluid strongly affect the cycle configuration. On the contrary species with critical temperatures closer to that of the base fluid such as CH₃F, CH₂F₂ or CHF₃ influence only marginally the cycle performance. In general a small concentration of decomposition products in the working medium is likely to be acceptable without noticeable drawbacks.     

Relative Permittivity and Resistivity of Liquid HFC Refrigerants Under High Pressure

The static relative permittivity (dielectric constant) and the resistivity of HFC-236ea (CF₃–CHF–CHF₂) and HFC-245fa (CF₃–CH₂–CHF₂) in the liquid phase were studied at temperatures from 293 to 343 K and pressures from 0.1 to 50 MPa. The relative permittivity was measured by a concentric-cylinder-type capacitance cell with an LCR meter with an uncertainty of less than 0.1%. The resistivity was measured by a high resistance meter using plane-parallel platinum electrodes installed in a borosilicate glass syringe. It was found that the relative permittivities and the resistivities of liquid HFC-236ea and HFC-245fa at 303 K and 0.101325 MPa are about 5.13 and 6.54 and 1.5×10¹⁰ and 0.2×10¹⁰ ·cm, respectively. The relative permittivity and the resistivity increase monotonically with increasing pressure and decreasing temperature.     

Thermodynamic properties of seven gaseous halogenated hydrocarbons from acoustic measurements: CHClFCF3, CHF2 CF3, CF3 CH3, CHF2CH3, CF3CHFCHF2, CF3CH2CF3, and CHF2CF2CH2F

Measurements of the speed of sound in seven halogenated hydrocarbons are presented. The compounds in this study are 1-chloro-1,2,2,2-tetrafluoroethane (CHClFCF₃ or HCFC-124), pentafluoroethane (CHF₂ CF₃ or HFC-125), 1,1,1-trifluoroethane (CF₃CH₃ or HFC-143a), 1,1-difluoroethane (CHF₂CH₃ or HFC-152a), 1,1,1,2,3,3-hexafluoropropane (CF₃CHFCHF₂ or HFC-236ea), 1,1,1,3,3,3-hexafluoropropane (CF₃CH₂CF₃ or HFC-236fa), and 1,1,2,2,3-pentafluoropropane (CHF₂CF₂CH₂F or HFC-245ca). The measurements were performed with a cylindrical resonator at temperatures between 240 and 400 K and at pressures up to 1.0 MPa. Ideal-gas heat capacities and acoustic virial coefficients were directly deduced from the data. The ideal-gas heat capacity of HFC-125 from this work differs from spectroscopic calculations by less than 0.2% over the measurement range. The coefficients for virial equations of state were obtained from the acoustic data and hard-core square-well intermolecular potentials. Gas densities that were calculated from the virial equations of state for HCFC-124 and HFC-125 differ from independent density measurements by at most 0.15%, for the ranges of temperature and pressure over which both acoustic and Burnett data exist. The uncertainties in the derived properties for the other five compounds are comparable to those for HCFC-124 and HFC-125.     

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.