Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
  • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
  • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
  • F25B9/006—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant containing more than one component
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
  • F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
  • F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
• • 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
  • C09K2205/10—Components
  • C09K2205/12—Hydrocarbons
  • C09K2205/126—Unsaturated fluorinated hydrocarbons
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
  • F25B2400/12—Inflammable refrigerants
  • F25B2400/121—Inflammable refrigerants using R1234

Definitions

• the present disclosure relates to a cascade refrigeration system which circulates a refrigerant comprising a fluoroolefin therethrough.
• a cascade system includes a medium temperature loop and a low temperature loop, and a fluoroolefin refrigerant may be used in either loop, or both.
• Cascade refrigeration systems are known in the art, see for example, ICR07-B2-358, "CO 2 -DX Systems for Medium-and Low- Temperature Refrigeration in Supermarket Applications", T. Sienel, O. Finckh, International Congress of Refrigeration, 2007, Beijing.
• Such a system typically uses a refrigerant such as 1 ,1 ,1 ,2- tetrafluoroethane (R134a) or blends thereof with HFC-125 and
• a refrigerant such as 1 ,1 ,1 ,2- tetrafluoroethane (R134a) or blends thereof with HFC-125 and
• HFC-143a i.e., R404A
• CO 2 carbon dioxide
• HFC-134a Currently proposed replacement refrigerants for HFC-134a include HFC-152a, pure hydrocarbons such as butane or propane, or "natural" refrigerants such as CO2. Many of these suggested replacements are toxic, flammable, and/or have low energy efficiency. New replacements are also being proposed for HCFC-22, R404A, R407C and R410A, among others. As these replacements are found, new uses of such alternative refrigerants are being sought in order to take advantage of their low or zero ozone depletion potential and lower global warming potential.
• the object of the present disclosure is to provide cascade
• cascade refrigeration system having at least two refrigeration loops, each circulating a refrigerant therethrough, comprising:
• a first compressor having an inlet and an outlet, wherein the first refrigerant vapor from the evaporator circulates to the inlet of the first compressor and is compressed, thereby increasing the pressure and the temperature of the first refrigerant vapor, and the compressed first refrigerant vapor circulates to the outlet of the first compressor;
• a second compressor having an inlet and an outlet, wherein the second refrigerant vapor from the cascade heat exchanger system is drawn into the compressor and is compressed, thereby increasing the pressure and temperature of the second refrigerant vapor;
• a condenser having an inlet and an outlet for circulating the second refrigerant vapor therethrough and for condensing the second refrigerant vapor from the compressor to form a second refrigerant liquid, wherein the second refrigerant liquid exits the condenser through the condenser outlet;
• Either the first refrigerant or the second refrigerant, or both, may comprise a fluoroolefin.
• the cascade heat exchanger system may include a first and a second cascade heat exchanger, and a secondary heat transfer loop which extends between the first and the second cascade heat exchanger.
• the second refrigerant liquid indirectly absorbs the heat rejected by the first refrigerant vapor through a heat transfer fluid which circulates between the first cascade heat exchanger and the second cascade heat exchanger through the secondary heat transfer loop.
• the first cascade heat exchanger has a first inlet and a first outlet, and a second inlet and a second outlet, wherein the first refrigerant vapor circulates from the first inlet to the first outlet and rejects heat and is condensed, and a secondary heat transfer fluid circulates from the second inlet to the second outlet and absorbs the heat rejected from the first refrigerant vapor and circulates to the second cascade heat exchanger.
• the second cascade heat exchanger has a first inlet and a first outlet, and a second inlet and a second outlet, wherein the heat transfer fluid circulates from the second outlet of the first cascade heat exchanger to the first inlet of the second cascade heat exchanger and to the first outlet of the second cascade heat exchanger and rejects the heat absorbed from the first refrigerant.
• the second refrigerant liquid circulates from the second inlet to the second outlet of the second cascade heat exchanger and absorbs the heat rejected by the heat transfer fluid and forms a second refrigerant vapor.
• either the first and/or second refrigerant may be, but need not necessarily be, a fluoroolefin.
• a method of exchanging heat between at least two refrigeration loops comprising:
• the refrigerant in at least one of the refrigeration loops comprises a fluoroolefin.
• FIG.1 is a schematic diagram of a cascade refrigeration system according to one embodiment of the present invention.
• FIG. 2 is a schematic diagram of another embodiment of the cascade refrigeration system of the present invention.
• FIG. 3 is a schematic diagram of a further embodiment of the present invention which shows a cascade refrigeration system with a secondary heat transfer loop which transfers heat from a lower temperature loop to a higher temperature loop.
• FIG. 4 is a schematic diagram of yet another embodiment of the cascade refrigeration system of the present invention which has multiple low temperature loops.
• FIG. 5 is a graph of the cooling capacity and COP for a refrigerant composition comprising HFO-1234yf and HFC-134a versus the weight percent of HFO-1234yf in the composition.
• Refrigeration capacity is a term to define the change in enthalpy of a refrigerant in an evaporator per unit mass of refrigerant circulated, or the heat removed by the refrigerant in the evaporator per unit volume of refrigerant vapor exiting the evaporator (volumetric capacity).
• the refrigeration capacity is a measure of the ability of a refrigerant or heat transfer composition to produce cooling.
• Cooling rate refers to the heat removed by the refrigerant in the evaporator per unit time.
• Coefficient of performance is the amount of heat removed from a body to be cooled divided by the required energy input to operate the cycle over a given time interval. The higher the COP, the higher is the energy efficiency. COP is directly related to the energy efficiency ratio (EER) that is the efficiency rating for refrigeration or air conditioning equipment at a specific set of internal and external temperatures.
• EER energy efficiency ratio
• Global warming potential is an index for estimating relative global warming contribution due to atmospheric emission of a kilogram of a particular greenhouse gas compared to emission of a kilogram of carbon dioxide. GWP can be calculated for different time horizons showing the effect of atmospheric lifetime for a given gas. The GWP for the 100 year time horizon is commonly the value referenced. For mixtures, a mass- fraction weighted average can be calculated based on the individual GWPs for each component.
• Ozone depletion potential is a number that refers to the amount of stratospheric ozone depletion caused by a substance. The ODP is the ratio of the impact on stratospheric ozone of a chemical compared to the impact of a similar mass of CFC-1 1
• CFC-1 1 fluorotrichloromethane
• HCFCs fluorotrichloromethane
• HFCs have zero ODP because they do not contain chlorine.
• compositions comprising, “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion.
• a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.
• “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
• a cascade refrigeration system having at least two refrigeration loops for circulating a refrigerant through each loop.
• a cascade system is shown generally at 10 in Fig. 1 .
• the cascade refrigeration system of the present invention has at least two refrigeration loops, including a first, or lower loop 12 as shown in FIG. 1 , which is a low temperature loop, and a second, or upper loop 14 as shown in FIG. 1 , which is a medium temperature loop 14.
• Each circulates a refrigerant therethrough.
• the cascade refrigeration system of the present invention includes a first expansion device 16.
• the first expansion device has an inlet 16a and an outlet 16b.
• the first expansion device reduces the pressure and temperature of a first refrigerant liquid which circulates through the first or low temperature loop.
• the cascade refrigeration system of the present invention also includes an evaporator 18 as shown in FIG. 1 .
• the evaporator has an inlet 18a and an outlet 18b.
• the first refrigerant liquid from the first expansion device enters the evaporator through the evaporator inlet and is evaporated in the evaporator to form a first refrigerant vapor.
• the first refrigerant vapor then circulates to the outlet of the evaporator.
• the cascade refrigeration system of the present invention also includes a first compressor 20.
• the first compressor has an inlet 20a and an outlet 20b.
• the first refrigerant vapor from the evaporator circulates to the inlet of the first compressor and is compressed, thereby increasing the pressure and the temperature of the first refrigerant vapor.
• compressed first refrigerant vapor then circulates to the outlet of the first compressor.
• the cascade refrigeration system of the present invention also includes a cascade heat exchanger system 22.
• the heat exchanger has a first inlet 22a and a first outlet 22b.
• the first refrigerant vapor from the first compressor enters the first inlet of the heat exchanger and is condensed in the heat exchanger to form a first refrigerant liquid, thereby rejecting heat.
• the first refrigerant liquid then circulates to the first outlet of the heat exchanger.
• the heat exchanger also includes a second inlet 22c and a second outlet 22d.
• a second refrigerant liquid circulates from the second inlet to the second outlet of the heat exchanger and is evaporated to form a second refrigerant vapor, thereby absorbing the heat rejected by the first refrigerant (as it is condensed). This heat is rejected to ambient.
• the second refrigerant vapor then circulates to the second outlet of the heat exchanger.
• the heat rejected by the first refrigerant is directly absorbed by the second refrigerant, and this heat is rejected to ambient.
• the cascade refrigeration system of the present invention also includes a second compressor 24 as shown in FIG. 1 .
• the second compressor has an inlet 24a and an outlet 24b.
• the second refrigerant vapor from the cascade heat exchanger is drawn into the compressor through the inlet and is compressed, thereby increasing the pressure and temperature of the second refrigerant vapor.
• the second refrigerant vapor then circulates to the outlet of the second compressor.
• the cascade refrigeration system of the present invention also includes a condenser 26 having an inlet 26a and an outlet 26b.
• the second refrigerant from the second compressor circulates from the inlet and is condensed in the condenser to form a second refrigerant liquid.
• the second refrigerant liquid exits the condenser through the outlet.
• the cascade refrigeration system of the present invention also includes a second expansion device 28 having an inlet 28a and an outlet 28b.
• the second refrigerant liquid passes through the second expansion device, which reduces the pressure and temperature of the second refrigerant liquid exiting the condenser. This liquid may be partially vaporized during this expansion.
• the reduced pressure and temperature second refrigerant liquid circulates to the second inlet of the cascade heat exchanger system from the expansion device.
• FIG. 1 various modifications to the embodiment as shown in FIG. 1 may be made without departing from the spirit or scope of the present invention.
• a secondary heat transfer loop as shown in this diagram, which uses a secondary heat transfer fluids such as glycol, may be used with the system of the present invention to transfer heat from bodies to be cooled (e.g., supermarket food display cases) to either the high or low refrigeration loops or both.
• the secondary heat transfer loop is used to transfer heat from a body to be cooled to the refrigeration loop, as opposed to a secondary heat transfer loop which is used to transfer heat between the refrigeration loops, as will be described below with respect to FIG. 3.
• either the first refrigerant or the second refrigerant in the cascade system of the embodiment of FIG. 1 may comprise a fluoroolefin.
• at least the second refrigerant i.e., the refrigerant which circulates through the medium temperature loop, comprises a fluoroolefin.
• the first refrigerant i.e., the refrigerant in the low temperature loop
• both the first and the second refrigerants to comprise a fluoroolefin.
• the first or the second refrigerant may be any of the fluoroolefins or mixtures of fluoroolefins or mixtures of fluoroolefins with additional refrigerants as described herein.
• Such fluoroolefins may be selected from the group consisting of:
• fluoroolefins selected from the group consisting of:
• fluoroolefins are compounds, which comprise carbon atoms, fluorine atoms and optionally hydrogen or chlorine atoms.
• the fluoroolefins used in the compositions of the present invention comprise compounds with 2 to 12 carbon atoms.
• the fluoroolefins comprise compounds with 3 to 10 carbon atoms, and in yet another embodiment the fluoroolefins comprise compounds with 3 to 7 carbon atoms.
• Representative fluoroolefins include but are not limited to all compounds as listed in Table 1 , Table 2, and Table 3.
• R 1 and R 2 groups include, but are not limited to, CF 3 , C 2 F 5 , CF 2 CF 2 CF 3 , CF(CF 3 ) 2 , CF 2 CF 2 CF 2 CF 3 ,
• the fluoroolefins of Formula (i) have at least 4 carbon atoms in the molecule.
• the first refrigerant is selected from fluoroolefins of Formula (i) having at least 5 carbon atoms in the molecule.
• the first refrigerant is selected from fluoroolefins of Formula (i) having at least 6 carbon atoms in the molecule.
• Exemplary, non-limiting Formula (i) compounds are presented in Table 1 .
• F16E CF 3 CH CH(CF 2 ) 5 CF 3 1 , 1 , 1 ,4,4, 5,5,6,6,7, 7, 8,8,9, 9, 9-hexadecafluoronon-2-ene
• F16sE CF 3 CH CHCF(CF 3 )(CF 2 ) 2 C 2 F5
• F16tE CF 3 CH CHC(CF 3 ) 2 CF 2 C 2 F 5 1 ,1 ,1 ,6,6,6-octafluoro-4,4-bis(trifluoromethyl)hept-2-ene
• F25E C 2 F 5 CH CH(CF 2 ) 4 CF 3 1 ,1 , 1 ,2,2, 5,5,6,6,7, 7, 8,8,9, 9, 9-hexadecafluoronon-3-ene
• F34E C 2 F 5 CF 2 CH CH-(CF 2 ) 3 CF 3 1 ,1 ,1 ,2,2,3,3,6,6J,7,8,8,9,9,9-hexadecafluoronon-4-ene
• F35iE C 2 F 5 CF 2 CH CH- 1 ,1 ,1 ,2,2,3,3,6,6,7,7,8,9,9,9-pentadecafluoro-8- Code Structure Chemical Name
• Compounds of Formula (i) may be prepared by contacting a
• perfluoroalkyltrihydroolefin of the formula R 1 CH CH 2 .
• perfluoroalkyltrihydroolefin may take place in batch mode by combining the reactants in a suitable reaction vessel capable of operating under the autogenous pressure of the reactants and products at reaction
• Suitable reaction vessels include fabricated from stainless steels, in particular of the austenitic type, and the well-known high nickel alloys such as Monel® nickel-copper alloys, Hastelloy® nickel based alloys and Inconel® nickel-chromium alloys.
• reaction may be conducted in semi-batch mode in which the perfluoroalkyltrihydroolefin reactant is added to the
• perfluoroalkyl iodide reactant by means of a suitable addition apparatus such as a pump at the reaction temperature.
• the ratio of perfluoroalkyl iodide to perfluoroalkyltrihydroolefin should be between about 1 :1 to about 4:1 , preferably from about 1 .5:1 to 2.5:1 . Ratios less than 1 .5:1 tend to result in large amounts of the 2:1 adduct as reported by Jeanneaux, et. al. in Journal of Fluorine Chemistry, Vol. 4, pages 261 -270 (1974).
• Preferred temperatures for contacting of said perfluoroalkyl iodide with said perfluoroalkyltrihydroolefin are preferably within the range of about 150°C to 300°C, preferably from about 170°C to about 250°C, and most preferably from about 180°C to about 230°C.
• Suitable contact times for the reaction of the perfluoroalkyl iodide with the perfluoroalkyltrihydroolefin are from about 0.5 hour to 18 hours, preferably from about 4 to about 12 hours.
• the trihydroiodoperfluoroalkane prepared by reaction of the perfluoroalkyl iodide with the perfluoroalkyltrihydroolefin may be used directly in the dehydroiodination step or may preferably be recovered and purified by distillation prior to the dehydroiodination step.
• the dehydroiodination step is carried out by contacting the
• Suitable basic substances include alkali metal hydroxides (e.g., sodium hydroxide or potassium hydroxide), alkali metal oxide (for example, sodium oxide), alkaline earth metal hydroxides (e.g., calcium hydroxide), alkaline earth metal oxides (e.g., calcium oxide), alkali metal alkoxides (e.g., sodium methoxide or sodium ethoxide), aqueous ammonia, sodium amide, or mixtures of basic substances such as soda lime.
• alkali metal hydroxides e.g., sodium hydroxide or potassium hydroxide
• alkali metal oxide for example, sodium oxide
• alkaline earth metal hydroxides e.g., calcium hydroxide
• alkaline earth metal oxides e.g., calcium oxide
• alkali metal alkoxides e.g., sodium methoxide or sodium ethoxide
• aqueous ammonia sodium amide
• Preferred basic substances are sodium hydroxide and potassium hydro
• Said contacting of the trihydroiodoperfluoroalkane with a basic substance may take place in the liquid phase preferably in the presence of a solvent capable of dissolving at least a portion of both reactants.
• Solvents suitable for the dehydroiodination step include one or more polar organic solvents such as alcohols (e.g., methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tertiary butanol), nitriles (e.g., acetonitrile, propionitrile, butyronitrile, benzonitrile, or adiponitrile), dimethyl sulfoxide, N,N-dimethylformamide, ⁇ , ⁇ -dimethylacetamide, or sulfolane.
• solvents e.g., methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tertiary butanol
• nitriles e.g., acetonitrile, propionitrile, butyronitrile, benzonit
• the dehydroiodination reaction may be carried out by addition of one of the reactants (either the basic substance or the trihydroiodoperfluoroalkane) to the other reactant in a suitable reaction vessel.
• Said reaction may be fabricated from glass, ceramic, or metal and is preferably agitated with an impeller or stirring mechanism.
• Temperatures suitable for the dehydroiodination reaction are from about 10°C to about 100°C, preferably from about 20°C to about 70°C.
• the dehydroiodination reaction may be carried out at ambient pressure or at reduced or elevated pressure.
• dehydroiodination reactions in which the compound of Formula (i) is distilled out of the reaction vessel as it is formed.
• the dehydroiodination reaction may be conducted by contacting an aqueous solution of said basic substance with a solution of the trihydroiodoperfluoroalkane in one or more organic solvents of lower polarity such as an alkane (e.g., hexane, heptane, or octane), aromatic hydrocarbon (e.g., toluene), halogenated hydrocarbon (e.g., methylene chloride, chloroform, carbon tetrachloride, or perchloroethylene), or ether (e.g., diethyl ether, methyl tert-butyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, dioxane, dimethoxyethane, diglyme, or tetraglyme) in the presence of a phase transfer catalyst.
• an alkane e.g., hexane, heptane, or oc
• Suitable phase transfer catalysts include quaternary ammonium halides (e.g., tetrabutylammonium bromide, tetrabutylammonium hydrosulfate, triethylbenzylammonium chloride, dodecyltrimethylammonium chloride, and tricaprylylmethylammonium chloride), quaternary phosphonium halides (e.g., quaternary ammonium halides (e.g., tetrabutylammonium bromide, tetrabutylammonium hydrosulfate, triethylbenzylammonium chloride, dodecyltrimethylammonium chloride, and tricaprylylmethylammonium chloride), quaternary phosphonium halides (e.g.,
• triphenylmethylphosphonium bromide and tetraphenylphosphonium chloride triphenylmethylphosphonium bromide and tetraphenylphosphonium chloride
• cyclic polyether compounds known in the art as crown ethers e.g., 18-crown-6 and 15-crown-5.
• the dehydroiodination reaction may be conducted in the absence of solvent by adding the trihydroiodoperfluoroalkane to a solid or liquid basic substance.
• Suitable reaction times for the dehydroiodination reactions are from about 15 minutes to about six hours or more depending on the solubility of the reactants. Typically the dehydroiodination reaction is rapid and requires about 30 minutes to about three hours for completion.
• the compound of Formula (i) may be recovered from the dehydroiodination reaction mixture by phase separation after addition of water, by distillation, or by a combination thereof.
• the fluoroolefins of Formula (ii) have at least about 3 carbon atoms in the molecule. In another embodiment, the fluoroolefins of Formula (ii) have at least about 4 carbon atoms in the molecule. In another embodiment, the fluoroolefins of Formula (ii) have at least about 5 carbon atoms in the molecule. In yet another embodiment, the
• fluoroolefins of Formula (ii) have at least about 6 carbon atoms in the molecule.
• Representative cyclic fluoroolefins of Formula (ii) are listed in Table 2.
• the first refrigerant of the present invention may comprise a single compound of Formula (i) or Formula (ii), for example, one of the compounds in Table 1 or Table 2, or may comprise a combination of compounds of Formula (i) or Formula (ii).
• the first refrigerant is selected from fluoroolefins comprising those compounds listed in Table 3.
• HFO-1234ye CHF 2 CF CHF 1 ,2,3,3-tetrafluoro-1-propene
• HFO-1234yf CF 3 CF CH 2 2,3,3,3-tetrafluoro-1-propene
• HFO-1234yc CH 2 FCF CF 2 1 , 1 ,2,3-tetrafluoro-1-propene
• HFO-1234zc CHF 2 CH CF 2 1 , 1 ,3,3-tetrafluoro-1-propene
• HFO-1243yf CHF 2 CF CH 2 2,3,3-trifluoro-1 -propene
• HFO-1243yc CH 3 CF CF 2 1 , 1 ,2-trifluoro-1 -propene
• HFO-1243zc CH 2 FCH CF 2 1 , 1 ,3-trifluoro-1 -propene
• HFO-1243ye CH 2 FCF CHF 1 , 2, 3-trifluoro-1 -propene
• HFO-1318cy CF 3 CF 2 CF CF 2 1 , 1 ,2,3,3,4,4,4-octafluoro-1-butene
• HFO-1327cz CF 2 CHCF 2 CF 3 1 , 1 ,3,3,4,4,4-heptafluoro-1-butene
• HFO-1327cye CF 2 CFCHFCF 3 1 , 1 ,2,3,4,4,4-heptafluoro-1-butene
• HFO-1327cyc CF 2 CFCF 2 CHF 2 1 , 1 ,2,3,3,4,4-heptafluoro-1-butene
• HFO-1336yf CF 3 CF 2 CF CH 2 2,3,3,4,4,4-hexafluoro-1-butene
• HFO-1336eye CHF CFCHFCF 3 1 ,2,3,4,4,4-hexafluoro-1-butene Name Structure Chemical name
• HFO-1336eyc CHF CFCF 2 CHF 2 1 ,2,3,3,4,4-hexafluoro-1-butene
• HFO-1336pyy CHF 2 CF CFCHF 2 1 , 1 ,2,3,4,4-hexafluoro-2-butene
• HFO-1336pz CHF 2 CH CFCF 3 1 , 1 ,1 ,2,4,4-hexafluoro-2-butene
• HFO-1336mzy CF 3 CH CFCHF 2 1 , 1 ,1 ,3,4,4-hexafluoro-2-butene
• HFO-1336pe CF 2 CFCHFCHF 2 1 , 1 ,2,3,4,4-hexafluoro-1-butene
• HFO- 1336ft CH 2 C(CF 3 ) 2
• HFO-1345mzy CF 3 CH CFCH 2 F 1 , 1 ,1 ,3,4-pentafluoro-2-butene
• HFO-1345mzz CHF 2 CH CHCF 3 1 , 1 ,1 ,4,4-pentafluoro-2-butene
• HFO-1345sy CH 3 CF CFCF 3 1 , 1 ,1 ,2,3-pentafluoro-2-butene
• HFO-1345fyc CH 2 CFCF 2 CHF 2 2,3,3,4,4-pentafluoro-1-butene
• HFO-1345pyz CHF 2 CF CHCHF 2 1 , 1 ,2,4,4-pentafluoro-2-butene
• HFO-1345cyc CH 3 CF 2 CF CF 2 1 , 1 ,2,3,3-pentafluoro-1-butene
• HFO-1345pyy CH 2 FCF CFCHF 2 1 , 1 ,2,3,4-pentafluoro-2-butene
• HFO-1345eyc CH 2 FCF 2 CF CHF 1 ,2,3,3,4-pentafluoro-1-butene
• HFO-1345ctm CF 2 C(CF 3 )(CH 3 )
• HFO-1345ftp CH 2 C(CHF 2 )(CF 3 )
• HFO-1345fye CH 2 CFCHFCF 3 2,3,4,4,4-pentafluoro-1-butene
• HFO-1345eyf CHF CFCH 2 CF 3 1 , 2,4,4, 4-pentafluoro-1-butene
• HFO-1345ezc CHF CHCF 2 CHF 2 1 ,3,3,4,4-pentafluoro-1-butene Name Structure Chemical name
• HFO-1345eye CHF CFCHFCHF 2 1 ,2,3,4,4-pentafluoro-1-butene
• HFO-1354fzc CH 2 CHCF 2 CHF 2 3,3,4,4-tetrafluoro-1-butene
• HFO-1354ctp CF 2 C(CHF 2 )(CH 3 )
• HFO-1354tfp CH 2 C(CHF 2 ) 2
• HFO-1354my CF 3 CF CHCH 3 1 , 1 ,1 ,2-tetrafluoro-2-butene
• HFO-1429myz CF 3 CF CHCF 2 CF 3
• HFO-1429eyc CHF CFCF 2 CF 2 CF 3
• HFO-1429czc CF 2 CHCF 2 CF 2 CF 3
• HFO-1429cycc CF 2 CFCF 2 CF 2 CHF 2
• HFO-1429myyc CF 3 CF CFCF 2 CHF 2
• HFO-1429eyym CHF CFCF(CF 3 ) 2 1 ,2,3,4,4,4-hexafluoro-3- Name Structure Chemical name
• HFO-1429cyzm CF 2 CFCH(CF 3 ) 2
• HFO-1438eycc CHF CFCF 2 CF 2 CHF 2
• HFO-1438ftmc CH 2 C(CF 3 )CF 2 CF 3
• HFO-1438czzm CF 2 CHCH(CF 3 ) 2
• HFO-1438ezym CHF CHCF(CF 3 ) 2
• HFO-1438ctmf CF 2 C(CF 3 )CH 2 CF 3
• HFO-1447fycc CH 2 CFCF 2 CF 2 CHF 2 2,3,3,4,4,5,5-heptafluoro-1-pentene
• HFO-1447mytm CF 3 CF C(CF 3 )(CH 3 )
• HFO-1447fyz CH 2 CFCH(CF 3 ) 2
• HFO-1447ezz CHF CHCH(CF 3 ) 2
• HFO-1456szy CF 3 CF 2 CF CHCH 3 3,4,4,5,5,5-hexafluoro-2-pentene
• HFO-1456fzce CH 2 CHCF 2 CHFCF 3 3,3,4,5,5,5-hexafluoro-1-pentene
• HFO-1456ftmf CH 2 C(CF 3 )CH 2 CF 3
• HFO-1549fztmm CH 2 CHC(CF 3 ) 3
• HFO-1549fycz CH 2 CFCF 2 CH(CF 3 ) 2
• HFO-1558szy CF 3 CF 2 CF 2 CF CHCH 3 3,4,4,5,5,6, 6,6-octafluoro-2-hexene Name Structure Chemical name
• HFO-1558fzccc CH 2 CHCF 2 CF 2 CF 2 CHF 2 3,3,4,4,5,5,6,6-octafluoro-2-hexene
• HFO-1558ftmf CH 2 C(CF 3 )CH 2 C 2 F 5
• HFO-1567szz CF 3 CF 2 CF 2 CH CHCH 3 4,4,5,5,6,6,6-heptafluoro-2-hexene
• HFO-1567fzfc CH 2 CHCH 2 CF 2 C 2 F5 4,4,5,5,6,6,6-heptafluoro-1-hexene
• HFO-1567sfyy CF 3 CF 2 CF CFC 2 H 5 1 , 1 ,1 ,2,2,3,4-heptafluoro-3-hexene
• HFO-1567fzfy CH 2 CHCH 2 CF(CF 3 ) 2
• HFO-1567myzzm CF 3 CF CHCH(CF 3 )(CH 3 )
• PEVE CF 2 CFOCF 2 CF 3 pentafluoroethyl trifluorovinyl ether
• 1,1,1 ,4,4-pentafluoro-2-butene may be prepared from 1,1,1 ,2,4,4- hexafluorobutane (CHF2CH2CHFCF3) by dehydrofluorination over solid KOH in the vapor phase at room temperature.
• CHF2CH2CHFCF3 1,1,1 ,4,4- hexafluorobutane
• 1,1,1 ,2,4,4-hexafluorobutane is described in US 6,066,768.
• 1,1,1 ,4,4,4- hexafluoro-2-butene may be prepared from 1,1,1 ,4,4,4-hexafluoro-2- iodobutane (CF3CHICH2CF3) by reaction with KOH using a phase transfer catalyst at about 60°C.
• 200-300°C.1,1,1,2,2,3,3-heptafluoropentane may be prepared by hydrogenation of 3,3,4,4,5, 5, 5-heptafluoro-1 -pentene
• 1,1,1,2,3,4-hexafluoro-2-butene may be prepared by
• 1,1,1,2,4,4-hexafluoro-2-butene may be prepared by
• 1,1,1,3,4,4-hexafluoro2-butene may be prepared by
• 1 ,1 ,1 ,3-tetrafluoro-2-butene may be prepared by reacting 1 ,1 ,1 ,3,3- pentafluorobutane ( CF3CH2CF2CH3) with aqueous KOH at 120 °C.
• CF3CHICH2CF2CF3 by reaction with KOH using a phase transfer catalyst at about 60°C.
• the synthesis of 4-iodo-1 ,1 ,1 ,2,2,5,5,5-octafluoropentane may be carried out by reaction of perfluoroethyliodide (CF 3 CF 2 I) and 3,3,3-trifluoropropene at about 200°C under autogenous pressure for about 8 hours.
• 1 ,1 ,1 ,2,2,5,5,6,6,6-decafluoro-3-hexene may be prepared from 1 ,1 ,1 ,2,2,5,5,6,6,6-decafluoro-3-iodohexane (CF3CF2CHICH2CF2CF3) by reaction with KOH using a phase transfer catalyst at about 60°C.
• perfluoroethyliodide CF 3 CF 2 I
• CF 3 CF 2 CH CH 2
• 1 ,1 ,1 ,4,5,5,5-heptafluoro-4-(trifluoromethyl)-2-pentene may be prepared by the dehydrofluorination of 1 ,1 ,1 , 2,5,5, 5-heptafluoro-4-iodo-2- (trifluoromethyl)-pentane (CF 3 CHICH 2 CF(CF 3 )2) with KOH in isopropanol.
• 2,3,3,4,4-pentafluoro-1 -butene may be prepared by
• F1 1 E is meant to represent the E-isomer, Z-isomer, or any combination or mixture of both isomers in any ratio.
• HFO-1225ye is meant to represent the E-isomer, Z-isomer, or any combination or mixture of both isomers in any ratio.
• the first refrigerant may be any of the single fluoroolefins of Formula (i), Formula (ii), Table 1 , Table 2 and Table 3, or may be any combination of the different fluoroolefins from Formula (i), Formula (ii), Table 1 , Table 2 and Table 3.
• the first refrigerant may be any combination of a single fluoroolefin or multiple fluoroolefins selected from Formula (i), Formula (ii), Table 1 , Table 2 and Table 3 with at least one additional refrigerant selected from hydrofluorocarbons, fluoroethers, hydrocarbons, CF 3 I, ammonia (NH 3 ), carbon dioxide (CO2), nitrous oxide (N 2 O), and mixtures thereof, meaning mixtures of any of the foregoing compounds.
• the first refrigerant may contain
• hydrofluorocarbons comprising at least one saturated compound containing carbon, hydrogen, and fluorine.
• hydrofluorocarbons having 1-7 carbon atoms and having a normal boiling point of from about -90°C to about 80°C.
• Hydrofluorocarbons are commercial products available from a number of sources or may be prepared by methods known in the art.
• hydrofluorocarbon compounds include but are not limited to fluoromethane (CH 3 F, HFC-41), difluoromethane (CH 2 F 2 , HFC-32), trifluoromethane (CHF 3 , HFC-23), pentafluoroethane (CF 3 CHF 2 , HFC-125), 1 ,1 ,2,2-tetrafluoroethane (CHF 2 CHF 2 , HFC-134), 1,1,1,2-tetrafluoroethane (CF 3 CH 2 F, HFC-134a), 1,1,1-trifluoroethane (CF 3 CH 3 , HFC-143a), 1 ,1-difluoroethane (CHF 2 CH 3 , HFC-152a), fluoroethane (CH 3 CH 2 F, HFC-161), 1,1,1,2,2,3,3- heptafluoropropane (CF 3 CF 2 CHF 2 , HFC-227ca), 1,1,1,2,3,3,3-
• the first refrigerant may further comprise fluoroethers.
• Fluoroethers comprise at least one compound having carbon, fluorine, oxygen and optionally hydrogen, chlorine, bromine or iodine. Fluoroethers are commercially available or may be produced by methods known in the art.
• fluoroethers include but are not limited to nonafluoromethoxybutane (C 4 F 9 OCH 3 , any or all possible isomers or mixtures thereof); nonafluoroethoxybutane (C F 9 OC 2 H 5 , any or all possible isomers or mixtures thereof); 2-difluoromethoxy-1 ,1 ,1 ,2- tetrafluoroethane (HFOC-236eaEpy, or CHF 2 OCHFCF 3 ); 1 ,1 -difluoro-2- methoxyethane (HFOC-272fbEpy,CH 3 OCH 2 CHF 2 ); 1 ,1 ,1 ,3,3,3-hexafluoro- 2-(fluoromethoxy)propane (HFOC-347mmzEpy, or CH 2 FOCH(CF 3 ) 2 ); 1 ,1 ,1 ,3,3,3-hexafluoro-2-methoxypropane (HFOC-356
• the first refrigerant may further comprise at least one hydrocarbon.
• Hydrocarbons are compounds having only carbon and hydrogen. Of particular utility are compounds having 3-7 carbon atoms. Hydrocarbons are commercially available through numerous chemical suppliers. Representative hydrocarbons include but are not-limited to propane, n-butane, isobutane, cyclobutane, n-pentane, 2-methylbutane, 2,2-dimethylpropane, cyclopentane, n-hexane,
• the disclosed compositions may comprise hydrocarbons containing heteroatoms, such as dimethylether (DME, CH 3 OCH 3 ).
• DME dimethylether
• the first refrigerant may further comprise carbon dioxide (CO 2 ), which is commercially available from various sources or may be prepared by methods known in the art.
• the first refrigerant may further comprise ammonia (NH 3 ), which is commercially available from various sources or may be prepared by methods known in the art.
• NH 3 ammonia
• the first refrigerant may further comprise iodotrifluoromethane (CF 3 I), which is commercially available from various sources or may be prepared by methods known in the art.
• CF 3 I iodotrifluoromethane
• the first and the second refrigerants may be as shown in the Table 4 below.
• the second refrigerant may consist essentially of HFO-1234yf. In other embodiments, the second refrigerant may comprise HFO-1234yf and R134a. In yet other embodiments, the second refrigerant may comprise HFO-1234yf and R32, or it may comprise trans HFO-1234ze and HFC-32, or trans HFO-1234ze and HFC- 134a or trans HFO-1234ze and HFC-125.
• the first refrigerant may comprise carbon dioxide (CO 2 ) or nitrous oxide (N 2 O).
• the first refrigerant may comprise HFO-1234yf and HFC-32.
• the first refrigerant may comprise trans HFO-1234ze and HFC-32.
• the first refrigerant may comprise either carbon dioxide or nitrous oxide.
• the first refrigerant may comprise HFO-1234yf and HFC-32.
• the first refrigerant may comprise trans HFO-1234ze and HFC-32.
• the second refrigerant may comprise 1 - 99% HFO-1234yf and 99 - 1 % HFC-134a.
• the second refrigerant comprises 1 - 53.1 % HFO-1234yf and 46.9 - 99% HFC-134a.
• the second refrigerant comprises 53% HFO-1234yf and 47% HFC-134a.
• the second refrigerant comprises 1 - 59% HFO-1234yf and 41 - 99% HFC-134a.
• the second refrigerant is non-flammable at 100° C or 60° C.
• This composition is non-flammable and has maximum capacity in the range of 40 - 59% 1234yf and 41 - 60% 134a.
• the second refrigerant may comprise 53% HFO-1234yf and 47% HFC-134a.
• the ranges for these components may be 1 - 99% HFO-1234yf and 99 - 1 % HFC-32.
• the second refrigerant may comprise 20 - 99% HFO-1234yf and 80 - 99% HFC-32. More particularly, the second refrigerant may comprise 50 - 99% HFO-1234yf and 50 - 99% HFC-32, and even more particularly, the second refrigerant may comprise 63% HFO-1234yf and 37% HFC-32.
• the second refrigerant may be used as a replacement for R404A.
• the second refrigerant may comprise 27.5% HFO-1234yf and 72.5% HFC-32.
• the second refrigerant may be used as a replacement for R41 OA.
• the first refrigerant may comprise either CO2 or N 2 O, a blend of HFO-1234yf/ HFC-32, or a blend of trans HFO-1234ze/HFC-32.
• the first refrigerant may comprise either carbon dioxide or nitrous oxide.
• the first refrigerant may comprise HFO-1234yf and HFC-32.
• the first refrigerant may comprise trans HFO-1234ze and HFC-32.
• the second refrigerant comprises trans HFO-1234ze and HFC-32
• the second refrigerant comprises 1 - 99% HFO-1234ze and 99 - 1 % HFC-32.
• the 1234ze may be either trans- 1234ze or cis-1234ze.
• the first refrigerant may comprise the first refrigerant may comprise either CO2 or N 2 O, a blend of HFO-1234yf/ HFC- 32, or a blend of trans HFO-1234ze/HFC-32.
• the first refrigerant may comprise either CO2 or N 2 O.
• the first refrigerant may comprise HFO-1234yf and HFC-32.
• the first refrigerant may comprise trans HFO-1234ze and HFC-32.
• the first refrigerant may comprise either carbon dioxide or nitrous oxide.
• the first refrigerant may comprise HFC-32 and HFO-1234yf.
• the first refrigerant may comprise trans HFO-1234ze and HFC-32.
• FIG. 2 shows a cascade system according to the present invention, where elements which correspond to the elements shown in FIG. 1 are indicated with a like reference numeral and a prime (').
• the elements in FIG. 2 which correspond to the elements shown in FIG. 1 all operate as described above with respect to FIG. 1 .
• the cascade system of FIG. 2 includes a secondary heat transfer loop, which includes a secondary fluid chiller 30 and a secondary fluid heat exchanger 32.
• the secondary fluid heat exchanger is located near a body to be cooled, such as food in a medium temperature display case.
• the secondary chiller cools a secondary heat transfer fluid.
• the use of a secondary heat transfer loop in the embodiment of FIG. 2 is advantageous because it limits the amount of refrigerant that must be used and the length of piping through which refrigerant must circulate, while at the same time
• the cascade refrigeration system of FIG. 2 also includes a cascade heat exchanger system disposed between the low temperature
• the cascade heat exchanger system has a first inlet 22a' and a first outlet 22b', wherein the first refrigerant vapor circulates from the first inlet to the first outlet and is condensed in the heat exchanger system to form a first refrigerant liquid, thereby rejecting heat.
• the cascade heat exchanger system also includes a second inlet 22c' and a second outlet 22d', wherein a second refrigerant liquid circulates from the second inlet to the second outlet and absorbs the heat rejected by the first refrigerant and forms a second refrigerant vapor, as will be explained below.
• the heat rejected by the first refrigerant is directly absorbed by the second refrigerant.
• a secondary heat transfer fluid enters the secondary chiller at a first inlet 30a and exits the secondary chiller at a first outlet 30b.
• the secondary heat transfer fluid may comprise ethylene glycol, propylene glycol, carbon dioxide, water brine or any of several other fluids or slurries known to the art.
• the secondary heat transfer fluid may undergo a phase change.
• the secondary chiller includes a second inlet 30c and a second outlet 30d. The second refrigerant enters the secondary fluid chiller through second inlet 30c and evaporates, thus causing the heat transfer fluid in the chiller to be cooled.
• the cooled heat transfer fluid exits the chiller 30 through first outlet 30b and circulates to a secondary fluid heat exchanger 32 located near a body to be cooled.
• This body to be cooled may be food items inside a refrigerated display case in a supermarket.
• the heat transfer fluid is warmed by this body and returns to the secondary fluid chiller to be cooled again by the evaporation of the second refrigerant, which also circulates through the secondary fluid chiller.
• a liquid pump (not shown) pumps the heat transfer fluid from the secondary fluid heat exchanger back to the secondary fluid chiller. This warmed heat transfer fluid causes the second refrigerant to evaporate in the secondary fluid chiller.
• a separate expansion device may be disposed in the inlet line entering cascade heat exchanger 22' and the inlet line entering secondary fluid chiller 30 in order to control the pressure and flow rate through the cascade heat exchanger and the secondary fluid chiller, respectively.
• cascade heat exchanger 22' and secondary fluid chiller 30 are shown connected in parallel, they may alternatively be connected in series without departing from the scope of the present invention.
• cascade heat exchanger 22' as in the first embodiment of FIG. 1 , the first refrigerant is condensed, and the second refrigerant evaporates and exits from the heat exchanger 22' at outlet 22d'.
• the second refrigerant which exits secondary fluid chiller 30 at second outlet 30d merges with the second refrigerant from outlet 22d' of the cascade heat exchanger and circulates to second compressor 24'.
• the cycle through medium temperature loop 14' and low temperature loop 12' are otherwise the same as discussed above with respect to FIG. 1 .
• FIG. 3 Another embodiment of the cascade refrigeration system of the present invention is shown in FIG. 3.
• elements which correspond to the elements shown in FIG. 1 are indicated with a like reference numeral and a double prime (").
• the elements in FIG. 3 which correspond to the elements shown in FIG. 1 all operate as described above with respect to FIG. 1 .
• the system of FIG. 3 includes a secondary heat transfer loop, shown generally at 40, which includes two cascade heat exchangers instead of one cascade heat exchanger as shown in the embodiments of FIGS. 1 and 2.
• FIG. 3 is advantageous because it limits the amount of refrigerant that must be used and the length of piping through which refrigerant must circulate, while at the same time transferring heat between locations that have to be remote from each other.
• the embodiment of FIG. 3 includes a cascade heat exchanger system which includes two cascade heat exchangers connected to each other through a secondary heat transfer loop.
• the cascade heat exchanger system in FIG. 3 has a first inlet 42a and a first outlet 42b, wherein the first refrigerant vapor circulates from the first inlet to the first outlet and is condensed in the cascade heat exchanger system to form a first refrigerant liquid, thereby rejecting heat.
• the cascade heat exchanger system also includes a second inlet 44c and a second outlet 44d, wherein a second refrigerant liquid circulates from the second inlet to the second outlet and indirectly absorbs the heat rejected by the first refrigerant and forms a second refrigerant vapor.
• the second refrigerant liquid indirectly absorbs the heat rejected by the first refrigerant through the secondary heat transfer fluid, that is to say, the first refrigerant rejects heat to the heat transfer fluid, and the heat transfer fluid circulates to the second cascade heat exchanger 44 where it transfers the heat from the first refrigerant to the second refrigerant, as will be described below. This heat is rejected to ambient.
• cascade refrigeration system 10 includes a first cascade heat exchanger 42 in low temperature loop 12", having a first inlet 42a and a first outlet 42b, and a second inlet 42c and a second outlet 42d.
• the medium temperature loop 14" includes a second cascade heat exchanger 44, having a first inlet 44a and a first outlet 44b, and a second inlet 44c and a second outlet 44d.
• Compressed first refrigerant vapor circulates from the outlet of the first compressor 20b" as shown in FIG. 3 to the first inlet 42a of the first heat exchanger 42.
• FIG. 3 Compressed first refrigerant vapor circulates from the outlet of the first compressor 20b" as shown in FIG. 3 to the first inlet 42a of the first heat exchanger 42.
• this compressed refrigerant vapor is condensed in the first cascade heat exchanger to form a first refrigerant liquid, thereby rejecting heat.
• the first refrigerant liquid then circulates to the first outlet 42b of the first cascade heat exchanger.
• a heat transfer fluid circulates in the secondary heat transfer loop between the first cascade heat exchanger and a second cascade heat exchanger 44, which is also part of the medium temperature loop 14". Specifically, the heat transfer fluid enters first heat exchanger 42 through a second inlet 42c and exits the first heat exchanger through a second outlet 42d. This heat transfer fluid absorbs the heat rejected by the condensing first refrigerant that enters that heat exchanger through inlet 42a, and is warmed.
• the warmed heat transfer fluid exits the first heat exchanger through second outlet 42d and circulates to second heat exchanger 44.
• the heat transfer fluid is cooled in the second heat exchanger by rejecting heat to the second refrigerant, which enters the second heat exchanger at a second inlet 44c, and exits the second heat exchanger at a second outlet 44d.
• the second refrigerant evaporates in the second cascade heat exchanger since it is warmed by the heat transfer fluid, and forms a second refrigerant vapor. Cooled heat transfer fluid exits the first outlet 44b of the second heat exchanger.
• the cycle through the low temperature loop 12" and the medium temperature loop 14" are otherwise the same as discussed above with respect to FIG. 1 , except that in this embodiment, the first and/or second refrigerant may be, but need not necessarily be, a fluoroolefin.
• FIG. 4 A further embodiment of the cascade refrigeration system of the present invention is shown in FIG. 4.
• elements which correspond to the elements shown in FIG. 1 are indicated with a like reference numeral and a triple prime ("').
• the elements in FIG. 4 which correspond to the elements shown in FIG. 1 all operate as described above with respect to FIG. 1 .
• the system of FIG. 4 includes two low temperature loops, Loop 12 A, which is similar to the low temperature loop 12 of FIG. 1 , and Loop 12B.
• One of the two low temperature loops, e.g., loop 12B provides refrigeration at a temperature which is different from, for example, intermediate to, the temperature at which refrigeration is provided by the other low temperature loop and by the medium temperature loop.
• the advantage of such a system is that the refrigerant in the low temperature loop can be used to cool two different bodies, such as two separate freezer display cases, at two different temperatures.
• a cascade heat exchanger system is disposed between the two loops.
• the cascade heat exchanger system has a first inlet 22a'" and a second inlet 22b'", and a first outlet 52 wherein the first refrigerant vapor circulates from the first and second inlets to the first outlet and is condensed in the heat exchanger system to form a first refrigerant liquid, thereby rejecting heat.
• the cascade heat exchanger system also includes a third inlet 22c'" and a second outlet 22d"', wherein a second refrigerant liquid circulates from the third inlet to the second outlet and absorbs the heat rejected by the first refrigerant and forms a second refrigerant vapor.
• the heat rejected by the first refrigerant is directly absorbed by the second refrigerant and this is rejected to ambient.
• FIG. 4 encompasses all cascade heat exchanger systems that transfer heat in the above described manner.
• the flow of the first refrigerant liquid is split as or after it exits the cascade heat exchanger 22"' at 52.
• One portion circulates through one low temperature loop 12A, and another portion circulates through the other low temperature loop 12B.
• the portion of the first refrigerant that circulates through loop 12B enters an additional expansion device 54 at inlet 54a, and the pressure and temperature of this portion of the first refrigerant liquid is reduced.
• This reduced pressure and temperature liquid refrigerant then circulates through outlet 54b of the additional expansion device, and circulates to an additional evaporator 56. It should be noted that this liquid may be partially vaporized during this expansion.
• the additional evaporator 56 includes an inlet 56a and an outlet 56b.
• Low temperature loop 12B also includes an additional compressor 58 having an inlet 58a and an outlet 58b.
• the first refrigerant vapor from additional evaporator 56 circulates to inlet 58a of the additional compressor 58 and is
• low temperature loop 12A and the medium temperature loop 14"' are otherwise the same as discussed above with respect to FIG. 1 .
• low temperature loop 12A also includes an evaporator 18"', which could be housed inside a freezer display case, and additional evaporator 56 could be housed inside a freezer display case. This system thereby could provide cooling to two separate freezer display cases.
• a method of exchanging heat between at least two refrigeration loops comprising: (a) absorbing heat from a body to be cooled in a first refrigeration loop and rejecting this heat to a second refrigeration loop; and (b) absorbing the heat from the first refrigeration loop in the second refrigeration loop and rejecting this heat to ambient.
• the refrigerant in either loop i.e., the loop in which heat is absorbed or the loop in which heat is rejected, or both, may comprise a fluoroolefin.
• the heat from the first refrigeration loop may be absorbed directly in the second refrigeration loop, such as in the embodiments of FIGS. 1 , 2 and 4, or it may be directly absorbed in the second refrigeration loop, such as in the embodiment of FIG. 3.
• Table 5 shows the performance of some exemplary compositions as compared to HFC-134a.
• Evap Pres is evaporator pressure
• Cond Pres is condenser pressure
• Comp Disch T is compressor discharge temperature
• COP coefficient of performance (analogous to energy efficiency)
• CAP capacity
• Avg. Temp glide is the average of the temperature glide in the evaporator and condenser
• GWP global warming potential. The data are based on the following conditions.
• Compressor efficiency is 70%
• the GWP value for HFC-134a is taken from the "Climate Change 2007 - IPCC (Intergovernmental Panel on Climate Change) Fourth Assessment Report on Climate Change", from the section entitled “Working Group 1 Report: "The Physical Science Basis", Chapter 2, pp. 212-213, Table 2.14.
• the value for HFO-1234yf was published in Papadimitriou et al., Physical Chemistry Chemical Physics, 2007, vol. 9, pp. 1 -13. Specifically, the 100 year time horizon GWP values are used.
• the GWP values for the compositions containing HFC-134a and HFO-1234yf are calculated as weighted averages of the individual component GWP values.
• compositions in the system have low temperature glide and a specific composition could be selected based on regulatory requirements for GWP, which have not at this time been determined.
• the composition containing 53 wt% HFO- 1234yf and 47 wt% HFC-134a has the particular benefit of providing a low GWP and a peak in the cooling capacity. This is shown graphically in FIG. 5.
• Flammable compositions may be identified by testing under ASTM (American Society of Testing and Materials) E681 -2004, with an electronic ignition source. Such tests of flammability were conducted on ASTM (American Society of Testing and Materials) E681 -2004, with an electronic ignition source. Such tests of flammability were conducted on ASTM (American Society of Testing and Materials) E681 -2004, with an electronic ignition source. Such tests of flammability were conducted on ASTM (American Society of Testing and Materials) E681 -2004, with an electronic ignition source. Such tests of flammability were conducted on ASTM (American Society of Testing and Materials) E681 -2004, with an electronic ignition source. Such tests of flammability were conducted on ASTM (American Society of Testing and Materials) E681 -2004, with an electronic ignition source. Such tests of flammability were conducted on ASTM (American Society of Testing and Materials) E681 -2004, with an electronic ignition source. Such tests of flammability were conducted on ASTM (American Society of Testing and Materials) E681 -2004, with an
• compositions containing HFO-1234yf and HFC-134a at 101 kPa compositions containing HFO-1234yf and HFC-134a at 101 kPa
• compositions with 66.25 weight percent or less HFO-1234yf in HFC-134a would be considered non-flammable.
• compositions with 60.00 weight percent or less HFO-1234yf in HFC-134a would be considered nonflammable.
• compositions containing 53.10 weight percent or less HFO-1234yf in HFC-134a would be considered non-flammable.
• Table 7 shows the performance of certain compositions as compared to CO 2 , R404A (ASHRAE designation for a mixture containing HFC-125, HFC-134a, and HFC-143a), R410A (ASHRAE designation for a mixture containing HFC-32 and HFC-125) and HFC-32.
• Evap Pres is evaporator pressure
• Cond Pres is condenser pressure
• Comp Disch T is compressor discharge temperature
• COP coefficient of performance (analogous to energy efficiency)
• CAP capacity
• Avg. Temp glide is the average of the temperature glide in the evaporator and condenser
• GWP global warming potential. The data are based on the following conditions.
• Compressor efficiency is 70%
• the GWP value for HFCs are taken from the "Climate Change 2007 - IPCC (Intergovernmental Panel on Climate Change) Fourth Assessment Report on Climate Change", from the section entitled “Working Group 1 Report: "The Physical Science Basis", Chapter 2, pp. 212-213, Table 2.14.
• the value for HFO-1234yf was published in Papadimitriou et al., Physical Chemistry Chemical Physics, 2007, vol. 9, pp. 1 -13. Specifically, the 100 year time horizon GWP values are used.
• compositions containing more than one component are calculated as weighted averages of the individual component GWP values.
• HFC-32 actually shows improved COP and capacity relative to R404A and also has significantly lower GWP.
• the composition containing 27.5 wt% HFO-1234yf and 72.5 wt% HFC-32 matches the COP and capacity of R410A, has very low temperature glide indicating azeotrope-like behavior and also has significantly lower GWP.
• compositions comprising mixtures of HFO-1234yf and HFC-32 have improved COP (energy efficiency) as compared to CO2.
• the total equivalent warming impact is determined for systems as disclosed herein in comparison to conventional uncoupled supermarket refrigeration systems as well as conventional cascade systems.
• the TEWI takes into consideration the effects of the energy efficiency of the system, the contribution due to the energy source used to provide the electrical power to the equipment, and the amount of refrigerant charged to the system as well as the rate of leakage to quantify a more complete environmental impact of use of different refrigerants.
• This Example uses a conventional European direct expansion (DX) supermarket refrigeration system, traditionally using R404A in both medium temperature (MT) and low temperature (LT) refrigeration systems, as the base case for comparison. Certain assumptions were made based on a typical European supermarket system are shown in Table 8.
• DX European direct expansion
• Table 9 provides the conditions for which the system performance (COP, or coefficient of performance, a measure of energy efficiency) was estimated.
• COP system performance
• temp is temperature
• evap is evaporator
• cond condenser
• comp is compressor.
• Table 10 lists several different embodiments of the present invention as compared to conventional uncoupled and cascade systems for which the determinations of TEWI are made, as well as the estimated COP values as calculated based on the conditions listed above in Table 9. TABLE 10
• the TEWI value includes an indirect contribution, which incorporates energy source and usage, and a direct contribution due to the emissions of refrigerant with a given GWP from a system.
• Table 1 1 lists the indirect and direct contributions and the TEWI value calculated for the different systems described above, in terms of equivalent CO2 emissions over equipment life (in million kg) in order from greatest to least environmental impact.
• Table 1 1 demonstrate that the use of HFO-based refrigerants (e.g. in the medium temperature loop of cascade refrigeration systems 3 and 4) can lead to lower TEWI values than those for uncoupled or cascade refrigeration systems using refrigerants known to the prior art.

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