共查询到19条相似文献,搜索用时 93 毫秒
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《化工新型材料》1997,(10)
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… 相似文献
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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。 相似文献
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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。 相似文献
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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. 相似文献
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第三代发泡剂HFC-245fa 总被引:1,自引:1,他引:0
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 相似文献
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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. 相似文献
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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. 相似文献17.
Y. Tanaka S. Matsuo T. Sotani T. Kondo T. Matsuo 《International Journal of Thermophysics》1999,20(1):107-117
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. 相似文献
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K. A. Gillis 《International Journal of Thermophysics》1997,18(1):73-135
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. 相似文献
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B. Sukornick 《International Journal of Thermophysics》1989,10(3):553-561
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. 相似文献