Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/02—Materials undergoing a change of physical state when used
  • C09K5/04—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa
  • C09K5/041—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems
  • C09K5/044—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems comprising halogenated compounds
  • C09K5/045—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems comprising halogenated compounds containing only fluorine as halogen
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K2205/00—Aspects relating to compounds used in compression type refrigeration systems
  • C09K2205/22—All components of a mixture being fluoro compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K2205/00—Aspects relating to compounds used in compression type refrigeration systems
  • C09K2205/32—The mixture being azeotropic

Definitions

• This invention relates to azeotrope-like or essentially constant-boiling mixtures of pentafluoroethane and 1,1,1-trifluoroethane. These mixtures are useful as refrigerants for heating and cooling.
• the high-pressure vapor then passes to the condenser whereupon heat exchange with a cooler medium, the sensible and latent heats are removed with subsequent condensation.
• the hot liquid refrigerant then passes to the expansion valve and is ready to cycle again. While the primary purpose of refrigeration is to remove energy at low temperature, the primary purpose of a heat pump is to add energy at higher temperature. Heat pumps ace considered reverse cycle systems because for heating, the operation of the condenser is interchanged with that of the refrigeration evaporator.
• Non-azeotropic mixtures have been disclosed as refrigerants for example in U. S. Patent 4.303.536 but have not found widespread use in commercial applications.
• the use of non-azeotropic mixtures which fractionate during the refrigeration cycle introduces additional complexity into the system which necessitates hardware changes.
• the use of non-azeotropic refrigerants has been avoided primarily due to the added difficulty in charging and servicing refrigeration equipment and the situation is further complicated if an inadvertent leak in the system occurs during use or during service.
• the composition of the mixture could change affecting system pressures and system performance. If one component of the non-azeotropic mixture is flammable, then fractionation could shift the composition into the flammable region with potential adverse consequences.
• hydrofluorocarbons such as pentafluoroethane(HFC-125) and 1,1,1-trifluoroethane(HFC-143a) will not adversely affect atmospheric chemistry. being negligible contributors to ozone depletion and to green-house global warming in comparison to the fully halogenated species.
• HFC-143a is as efficient as R-502 and provides a modest increase in refrigeration capacity.
• novel azeotrope-like compositions comprising pentafluoroethane and 1,1,1-trifluoroethane.
• the azeotrope-like compositions comprise from about 1 to about 80 weight percent pentafluocoethane and from about 20 to about 99 weight percent 1,1,1-trifluoroethane which have a vapor pressure of about 167 psia(1113 kPa) ⁇ about 6 psia(40 kPa) at 70°F(21.1oC).
• These compositions ace azeotrope-like because they ace constant-boiling, i.e. exhibit essentially constant-vapor pressure versus composition and essentially identical liquid and vapor compositions over the aforementioned compositional ranges.
• the azeotrope-like compositions of the invention comprise from about 38.4 to about 80 weight percent pentafluoroethane and from about 20 to about 61.6 weight percent 1,1,1-trifluocoethane .
• Vapor phase compositions containing in excess of about 38.4 weight percent pentafluoroethane were determined to be nonflammable in air at ambient conditions using the ASTM E-681 method as specified in the American Society of Heating. Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 34.
• the azeotrope-like compositions of the invention comprise from about 40 to about 80 weight percent pentafluoroethane and from about 20 to about 60 weight percent 1,1,1-trifluoroethane. These compositions are constant-boiling, non-segregating, and nonflammable.
• HFC-125 and HFC-143a were disclosed as having utility as a refrigerant in RESEARCH DISCLOSURE 15402, February 1977 but this disclosure implied that such a blend was non-azeotcopic. i.e. would fractionate upon e vaporation or condensation, and stated that the blend was disadvantageous because it was flammable. Contrary to this teaching, we have discovered that the blends of HFC-125 and HFC-143a as recited above ace both constant-boiling, i.e. azeotrope-like. and ace nonflammable.
• compositions of pentafluoroethane and 1,1,1-trifluoroethane are constant-boiling or essentially constant-boiling.
• azeotrope-like composition is intended to mean that the composition behaves like an azeotrope. i.e. has constant-boiling characteristics or a tendency not to fractionate upon boiling or evaporation.
• composition changes to a substantial degree.
• one way to detecmine whether a candidate mixture is "azeotrope-like" within the meaning of this invention is to distill a sample thereof under conditions (i.e. resolution - number of plates) which would be
• the mixture is non-azeotropic or non-azeotrope-like.
• the mixture will fractionate, i.e.
• the azeotrope-like compositions of the invention may be used in a method foe producing refrigeration which comprises condensing a refrigerant comprising the azeotrope-like compositions and thereafter evaporating the refrigerant in the vicinity of a body to be cooled.
• the azeotrope-like compositions of the invention may be used in a method foe producing heating which comprises
• the pentafluoroethane and 1.1,1-trifluoroethane of the novel azeotrope-like compositions of the invention are known materials.
• the materials should be used in sufficiently high purity so as to avoid the
• compositions may include additional components so as to form new azeotrope-like compositions. Any such
• compositions are considered to be within the scope of the present invention as long as the compositions are constant-boiling or essentially constant-boiling and contain all of the essential components described herein.
• compositions of pentafluoroethane and 1,1,1-trifluoroethane are azeotrope-like. i.e. exhibit essentially identical liquid and vapor compositions. and ace constant-boiling, i.e. exhibit essentially constant vapor pressure versus composition within this range.
• the vessel equipped with a magnetically driven stirrer and a 0-300 psia(0-2068 kPa) pressure transducer rccurate to +0.2%. was submerged in a constant temperature bath controlled to within ⁇ 0.05oF(0.03oC). Once thermal equilibrium was attained, as determined by constant vapor pressure
• Flammability measurements were performed using the ASTM E-681 technique modified according to ASHRAE Standard 34. Briefly, this technique involves preparing
• composition i.e. the composition of the HFC-125/HFC-143a blend which contains the maximum proportion of the
• thermodynamic properties of a refrigerant can be estimated from the thermodynamic properties of the refrigerant using standard refrigeration cycle analysis techniques; see for example, R. C. Downing. FLUOROCARBONS REFRIGERANTS HANDBOOK.
• this teem expresses the ratio of useful refrigeration to the energy applied by the compressor in compressing the vapor.
• the capacity of a refrigerant represents the volumetric effectiveness of the
• HFC-125/HFC-143a blend provides essentially the same
• COP(within ⁇ 1%) as that attainable with R-502. provides about a 7% increase in refrigeration capacity, and also produces lower discharge temperatures from the compressor, which contributes to compressor reliability. It has been recommended that compressor discharge temperatures be limited to about 225oF(107.2°C). This temperature is exceeded in the current example by R-502 at evaporator temperatures lower than -35oF(-37.2oC): the HFC-125/

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• Chemical & Material Sciences (AREA)
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• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Combustion & Propulsion (AREA)
• Thermal Sciences (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Detergent Compositions (AREA)

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• 1993
  • 1993-05-13 WO PCT/US1993/004577 patent/WO1994026836A1/en not_active Application Discontinuation
  • 1993-05-13 JP JP6525363A patent/JPH08511043A/ja active Pending
  • 1993-05-13 CA CA002161813A patent/CA2161813C/en not_active Expired - Lifetime
  • 1993-05-13 EP EP93911313A patent/EP0705317A1/de not_active Ceased
  • 1993-05-13 AU AU40423/93A patent/AU690066B2/en not_active Expired

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