Patent Application
20110290447
1. Field of the Invention
The present disclosure relates to a method for exchanging heat in a vapor compression heat transfer system. In particular, it relates to use of an intermediate heat exchanger to improve performance of a vapor compression heat transfer system utilizing a working fluid comprising at least one fluoroolefin.
2. Description of Related Art
Methods for improving the performance of heat transfer systems, such as refrigeration systems and air conditioners, are always being sought, in order to reduce cost of operation of such systems.
When new working fluids for heat transfer systems, including vapor compression heat transfer systems, are being proposed it is important to be able to provide means of improving cooling capacity and energy efficiency for the new working fluids.
Applicants have found that the use of an internal heat exchanger in a vapor compression heat transfer system that uses a fluoroolefin provides unexpected benefits due to sub-cooling of the working fluid exiting out of the condenser. By “subcooling” is meant the reduction of the temperature of a liquid below that liquid's saturation point for a given pressure. The saturation point is the temperature at which the vapor usually would condense to a liquid, but subcooling produces a lower temperature vapor at the given pressure. By cooling a vapor below the saturation point, the net refrigeration capacity can be increased. Sub-cooling thereby improves cooling capacity and energy efficiency of a system, such as vapor compression heat transfer systems, which comprise fluoroolefins.
In particular, when the fluoroolefin 2,3,3,3-tetrafluoropropene (HFC-1234yf) is used as the working fluid, surprising results have been achieved with respect to coefficient of performance and capacity of the working fluid, as compared to the use of known working fluids such as 1,1,1,2-tetrafluoroethane (HFC-124a).
Therefore, in accordance with the present invention, the present disclosure provides a method of exchanging heat in a vapor compression heat transfer system, comprising:
The fluorolefin is a compound selected from the group consisting of:
In addition, sub-cooling has been found to enhance the performance and efficiency of systems which use cross-current/counter-current heat exchange, such as those which employ either a dual-row condenser or a dual-row evaporator.
Therefore, further in accordance with the method of the present invention, the present disclosure also provides that the condensing step may comprise:
Further in accordance with the method of the present invention, the present disclosure also provides that the evaporating step may comprise:
Also in accordance with the present invention, there is provided a vapor compression heat transfer system for exchanging heat comprising an intermediate heat exchanger in combination with a dual-row condenser or a dual-row evaporator, or both.
The present invention may be better understood with reference to the following figures, wherein:
One embodiment of the present disclosure provides a method of circulating a working fluid comprising a fluoroolefin through a vapor compression heat transfer system. A vapor-compression heat transfer system is a closed loop system which re-uses working fluid in multiple steps producing a cooling effect in one step and a heating effect in a different step. Such a system generally includes an evaporator, a compressor, a condenser and an expansion device, and is known in the art. Reference will be made to
With reference to
In an intermediate heat exchanger, the first tube containing the relatively hotter liquid working fluid and the second tube containing the relatively colder gaseous working fluid are in thermal contact, thus allowing transfer of heat from the hot liquid to the cold gas. The means by which the two tubes are in thermal contact may vary. In one embodiment, the first tube has a larger diameter than the second tube, and the second tube is disposed concentrically in the first tube, and a hot liquid in the first tube surrounds a cold gas in the second tube. This embodiment is shown in
Also, in one embodiment, the working fluid in the second tube of the internal heat exchanger may flow in a countercurrent direction to the direction of flow of the working fluid in the first tube, thereby cooling the working fluid in the first tube and heating the working fluid in the second tube.
Cross-current/counter-current heat exchange may be provided in the system of
Therefore, in accordance with the present invention, there is provided a vapor compression heat transfer system which comprises either a dual-row condenser, or a dual-row evaporator, or both. Such a system is the same as that described above with respect to
Reference will be made to
Reference will be made to
In the embodiments as shown in
Various types of compressors may be used in the vapor compression heat transfer system of the embodiments of the present invention, including reciprocating, rotary, jet, centrifugal, scroll, screw or axial-flow, depending on the mechanical means to compress the fluid, or as positive-displacement (e.g., reciprocating, scroll or screw) or dynamic (e.g., centrifugal or jet).
In certain embodiments the heat transfer systems as disclosed herein may employ fin and tube heat exchangers, microchannel heat exchangers and vertical or horizontal single pass tube or plate type heat exchangers, among others for both the evaporator and condenser.
The closed loop vapor compression heat transfer system as described herein may be used in stationary refrigeration, air-conditioning, and heat pumps or mobile air-conditioning and refrigeration systems. Stationary air-conditioning and heat pump applications include window, ductless, ducted, packaged terminal, chillers and light commercial and commercial air-conditioning systems, including packaged rooftop. Refrigeration applications include domestic or home refrigerators and freezers, ice machines, self-contained coolers and freezers, walk-in coolers and freezers and supermarket systems, and transport refrigeration systems.
Mobile refrigeration or mobile air-conditioning systems refer to any refrigeration or air-conditioning system incorporated into a transportation unit for the road, rail, sea or air. In addition, apparatus, which are meant to provide refrigeration or air-conditioning for a system independent of any moving carrier, known as “intermodal” systems, are included in the present invention. Such intermodal systems include “containers” (combined sea/land transport) as well as “swap bodies” (combined road and rail transport). The present invention is particularly useful for road transport refrigerating or air-conditioning apparatus, such as automobile air-conditioning apparatus or refrigerated road transport equipment.
The working fluid utilized in the vapor compression heat transfer system comprises at least one fluoroolefin. By fluoroolefin is meant any compound containing carbon, fluorine and optionally, hydrogen or oxygen that also contains at least one double bond. These fluoroolefins may be linear, branched or cyclic.
Fluoroolefins have a variety of utilities in working fluids, which include use as foaming agents, blowing agents, fire extinguishing agents, heat transfer mediums (such as heat transfer fluids and refrigerants for use in refrigeration systems, refrigerators, air-conditioning systems, heat pumps, chillers, and the like), to name a few.
In some embodiments, heat transfer compositions may comprise fluoroolefins comprising at least one compound with 2 to 12 carbon atoms, in another embodiment 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.
In one embodiment, the present methods use working fluids comprising fluoroolefins having the formula E- or Z—R1CH═CHR2 (Formula I), wherein R1 and R2 are, independently, C1 to C6 perfluoroalkyl groups. Examples of R1 and R2 groups include, but are not limited to, CF3, C2F5, CF2CF2CF3, CF(CF3)2, CF2CF2CF2CF3, CF(CF3)CF2CF3, CF2CF(CF3)2, C(CF3)3, CF2CF2CF2CF2CF3, CF2CF2CF(CF3)2, C(CF3)2C2F5, CF2CF2CF2CF2CF2CF3, CF(CF3) CF2CF2C2F5, and C(CF3)2CF2C2F5. In one embodiment the fluoroolefins of Formula I, have at least about 4 carbon atoms in the molecule. In another embodiment, the fluoroolefins of Formula I have at least about 5 carbon atoms in the molecule. Exemplary, non-limiting Formula I compounds are presented in Table 1.
Compounds of Formula I may be prepared by contacting a perfluoroalkyl iodide of the formula R11 with a perfluoroalkyltrihydroolefin of the formula R2CH═CH2 to form a trihydroiodoperfluoroalkane of the formula R1CH2CHIR2. This trihydroiodoperfluoroalkane can then be dehydroiodinated to form R1CH═CHR2. Alternatively, the olefin R1CH═CHR2 may be prepared by dehydroiodination of a trihydroiodoperfluoroalkane of the formula R1CHICH2R2 formed in turn by reacting a perfluoroalkyl iodide of the formula R2I with a perfluoroalkyltrihydroolefin of the formula R1CH═CH2.
Said contacting of a perfluoroalkyl iodide with a 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 temperature. 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.
Alternatively, the reaction may take 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 trihydroiodoperfluoroalkane with a basic substance. 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. Preferred basic substances are sodium hydroxide and potassium hydroxide.
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, N,N-dimethylacetamide, or sulfolane. The choice of solvent may depend on the boiling point product and the ease of separation of traces of the solvent from the product during purification. Typically, ethanol or isopropanol are good solvents for the reaction.
Typically, 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. Of note are dehydroiodination reactions in which the compound of Formula I is distilled out of the reaction vessel as it is formed.
Alternatively, 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. 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., triphenylmethylphosphonium bromide and tetraphenylphosphonium chloride), or cyclic polyether compounds known in the art as crown ethers (e.g., 18-crown-6 and 15-crown-5).
Alternatively, 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.
In another embodiment of the present invention, fluoroolefins comprise cyclic fluoroolefins (cyclo-[CX═CY(CZW)n—] (Formula II), wherein X, Y, Z, and W are independently selected from H and F, and n is an integer from 2 to 5). In one embodiment 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 yet another embodiment, the fluoroolefins of Formula II have at least about 5 carbon atoms in the molecule. Representative cyclic fluoroolefins of Formula II are listed in Table 2.
The compositions 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.
In another embodiment, fluoroolefins may comprise those compounds listed in Table 3.
The compounds listed in Table 2 and Table 3 are available commercially or may be prepared by processes known in the art or as described herein.
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. The synthesis of 1,1,1,2,4,4-hexafluorobutane is described in U.S. Pat. No. 6,066,768, incorporated herein by reference.
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. The synthesis of 1,1,1,4,4,4-hexafluoro-2-iodobutane may be carried out by reaction of perfluoromethyl iodide (CF3I) and 3,3,3-trifluoropropene (CF3CH═CH2) at about 200° C. under autogenous pressure for about 8 hours.
3,4,4,5,5,5-hexafluoro-2-pentene may be prepared by dehydrofluorination of 1,1,1,2,2,3,3-heptafluoropentane (CF3CF2CF2CH2CH3) using solid KOH or over a carbon catalyst at 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 (CF3CF2CF2CH═CH2).
1,1,1,2,3,4-hexafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,3,3,4-heptafluorobutane (CH2FCF2CHFCF3) using solid KOH.
1,1,1,2,4,4-hexafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,2,4,4-heptafluorobutane (CHF2CH2CF2CF3) using solid KOH.
1,1,1,3,4,4-hexafluoro2-butene may be prepared by dehydrofluorination of 1,1,1,3,3,4,4-heptafluorobutane (CF3CH2CF2CHF2) using solid KOH.
1,1,1,2,4-pentafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,2,2,3-hexafluorobutane (CH2FCH2CF2CF3) using solid KOH.
1,1,1,3,4-pentafluoro-2-butene may be prepared by dehydrofluorination of 1,1,1,3,3,4-hexafluorobutane (CF3CH2CF2CH2F) using solid KOH.
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.
1,1,1,4,4,5,5,5-octafluoro-2-pentene may be prepared from (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 (CF3CF2I) 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. The synthesis of 1,1,1,2,2,5,5,6,6,6-decafluoro-3-iodohexane may be carried out by reaction of perfluoroethyliodide (CF3CF2I) and 3,3,4,4,4-pentafluoro-1-butene (CF3CF2CH═CH2) at about 200° C. under autogenous pressure for about 8 hours.
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 (CF3CHICH2CF(CF3)2) with KOH in isopropanol. CF3CHICH2CF(CF3)2 is made from reaction of (CF3)2CFI with CF3CH═CH2 at high temperature, such as about 200° C.
1,1,1,4,4,5,5,6,6,6-decafluoro-2-hexene may be prepared by the reaction of 1,1,1,4,4,4-hexafluoro-2-butene (CF3CH═CHCF3) with tetrafluoroethylene (CF2═CF2) and antimony pentafluoride (SbF5).
2,3,3,4,4-pentafluoro-1-butene may be prepared by dehydrofluorination of 1,1,2,2,3,3-hexafluorobutane over fluorided alumina at elevated temperature.
2,3,3,4,4,5,5,5-ocatafluoro-1-pentene may be prepared by dehydrofluorination of 2,2,3,3,4,4,5,5,5-nonafluoropentane over solid KOH.
1,2,3,3,4,4,5,5-octafluoro-1-pentene may be prepared by dehydrofluorination of 2,2,3,3,4,4,5,5,5-nonafluoropentane over fluorided alumina at elevated temperature.
Many of the compounds of Formula I, Formula II, Table 1, Table 2, and Table 3 exist as different configurational isomers or stereoisomers. When the specific isomer is not designated, the described composition is intended to include all single configurational isomers, single stereoisomers, or any combination thereof. For instance, F11E is meant to represent the E-isomer, Z-isomer, or any combination or mixture of both isomers in any ratio. As another example, HFC-1225ye is meant to represent the E-isomer, Z-isomer, or any combination or mixture of both isomers in any ratio, with the Z isomer preferred.
In some embodiments, the working fluid may further comprise at least one compound selected from hydrofluorocarbons, fluoroethers, hydrocarbons, dimethyl ether (DME), carbon dioxide (CO2), ammonia (NH3), and iodotrifluoromethane (CF3I).
In some embodiments, the working fluid may further comprise hydrofluorocarbons comprising at least one saturated compound containing carbon, hydrogen, and fluorine. Of particular utility are hydrofluorocarbons having 1 to 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. Representative hydrofluorocarbon compounds include but are not limited to fluoromethane (CH3F, HFC-41), difluoromethane (CH2F2, HFC-32), trifluoromethane (CHF3, HFC-23), pentafluoroethane (CF3CHF2, HFC-125), 1,1,2,2-tetrafluoroethane (CHF2CHF2, HFC-134), 1,1,1,2-tetrafluoroethane (CF3CH2F, HFC-134a), 1,1,1-trifluoroethane (CF3CH3, HFC-143a), 1,1-difluoroethane (CHF2CH3, HFC-152a), fluoroethane (CH3CH2F, HFC-161), (CF3CF2CHF2, HFC-227ca), 1,1,1,2,3,3,3-heptafluoropropane (CF3CHFCF3, HFC-227ea), 1,2,2,3,3-hexafluoropropane (CHF2CF2CHF2, HFC-236ca), 1,1,1,2,2,3-hexafluoropropane (CF3CF3CH2F, HFC-236cb), 1,1,2,3,3-hexafluoropropane (CF3CHFCHF2, HFC-236ea), 1,1,1,3,3,3-hexafluoropropane (CF3CH2CF3, HFC-236fa), 1,1,2,2,3-pentafluoropropane (CHF2CF2CH2F, HFC-245ca), 1,1,1,2,2-pentafluoropropane (CF3CF2CH3, HFC-245cb), 1,1,2,3,3-pentafluoropropane (CHF2CHFCHF2, HFC-245ea), 1,1,1,2,3-pentafluoropropane (CF3CHFCH2F, HFC-245eb), 1,1,1,3,3-pentafluoropropane (CF3CH2CHF2, HFC-245fa), 1,2,2,3-tetrafluoropropane (CH2FCF2CH2F, HFC-254ca), 1,1,2,2-tetrafluoropropane (CHF2CF2CH3, HFC-254cb), 1,1,2,3-tetrafluoropropane (CHF2CHFCH2F, HFC-254ea), 1,1,1,2-tetrafluoropropane (CF3CHFCH3, HFC-254eb), 1,1,3,3-tetrafluoropropane (CHF2CH2CHF2, HFC-254fa), 1,1,1,3-tetrafluoropropane (CF3CH2CH2F, HFC-254fb), 1,1,1-trifluoropropane (CF3CH2CH3, HFC-263fb), 2,2-difluoropropane (CH3CF2CH3, HFC-272ca), 1,2-difluoropropane (CH2FCHFCH3, HFC-272ea), 1,3-difluoropropane (CH2FCH2CH2F, HFC-272fa), 1,1-difluoropropane (CHF2CH2CH3, HFC-272fb), 2-fluoropropane (CH3CHFCH3, HFC-281ea), 1-fluoropropane (CH2FCH2CH3, HFC-281fa), 1,1,2,2,3,3,4,4-octafluorobutane (CHF2CF2CF2CHF2, HFC-338 pcc), 1,1,1,2,2,4,4,4-octafluorobutane (CF3CH2CF2CF3, HFC-338mf), 1,1,1,3,3-pentafluorobutane (CF3CH2CHF2, HFC-365mfc), 1,1,1,2,3,4,4,5,5,5-decafluoropentane (CF3CHFCHFCF2CF3, HFC-43-10mee), and 1,1,1,2,2,3,4,5,5,6,6,7,7,7-tetradecafluoroheptane (CF3CF2CHFCHFCF2CF2CF3, HFC-63-14mee).
In some embodiments, working fluids may further comprise fluoroethers comprising 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. Representative fluoroethers include but are not limited to nonafluoromethoxybutane (C4F9OCH3, any or all possible isomers or mixtures thereof); nonafluoroethoxybutane (C4F9OC2H5, any or all possible isomers or mixtures thereof); 2-difluoromethoxy-1,1,1,2-tetrafluoroethane (HFOC-236eaEβγ, or CNF2OCHFCF3); 1,1-difluoro-2-methoxyethane (HFOC-272fbEβγ, CH3OCH2CHF2); 1,1,1,3,3,3-hexafluoro-2-(fluoromethoxy)propane (HFOC-347mmzEβγ, or CH2FOCH(CF3)2); 1,1,1,3,3,3-hexafluoro-2-methoxypropane (HFOC-356mmzEβγ, or CH3OCH(CH3)2); 1,1,1,2,2-pentafluoro-3-methoxypropane (HFOC-365mcEγδ, or CF3CF2CH2OCH3); 2-ethoxy-1,1,1,2,3,3,3-heptafluoropropane (HFOC-467mmyEβγ, or CH3CH2OCF(CF3)2; and mixtures thereof.
In some embodiments, working fluids may further comprise hydrocarbons comprising compounds having only carbon and hydrogen. Of particular utility are compounds having 3 to 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, 2-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 3-methylpentane, cyclohexane, n-heptane, and cycloheptane.
In some embodiments, the working fluid may comprise hydrocarbons containing heteroatoms, such as dimethylether (DME, CH3OCH3). DME is commercially available.
In some embodiments, working fluids may further comprise carbon dioxide (CO2), which is commercially available from various sources or may be prepared by methods known in the art.
In some embodiments, working fluids may further comprise ammonia (NH3), which is commercially available from various sources or may be prepared by methods known in the art.
In some embodiments, the working fluid further comprises at least one compound selected from hydrofluorocarbons, fluoroethers, hydrocarbons, dimethyl ether (DME), carbon dioxide (CO2), ammonia (NH3), and iodotrifluoromethane (CF3I).
In one embodiment, the working fluid comprises 1,2,3,3,3-pentafluoropropene (HFC-1225ye). In another embodiment, the working fluid further comprises difluoromethane (HFC-32). In yet another embodiment, the working fluid further comprises 1,1,1,2-tetrafluoroethane (HFC-134a).
In one embodiment, the working fluid comprises 2,3,3,3-tetrafluoropropene (HFC-1234yf). In another embodiment, the working fluid comprises HFC-1225ye and HFC-1234yf.
In one embodiment, the working fluid comprises 1,3,3,3-tetrafluoropropene (HFC-1234ze). In another embodiment, the working fluid comprises E-HFC-1234ze (or trans-HFC-1234ze).
In yet another embodiment, the working fluid further comprises at least one compound from the group consisting of HFC-134a, HFC-32, HFC-125, HFC-152a, and CF3I.
In certain embodiments, working fluids may comprise a composition selected from the group consisting of:
HFC-32 and HFC-1225ye;
HFC-1234yf and CF3I;
HFC-32, HFC-134a, and HFC-1225ye;
HFC-32, HFC-125, and HFC-1225ye;
HFC-32, HFC-1225ye, and HFC-1234yf;
HFC-125, HFC-1225ye, and HFC-1234yf;
HFC-32, HFC-1225ye, HFC-1234yf, and CF3I;
HFC-134a, HFC-1225ye, and HFC-1234yf;
HFC-134a and HFC-1234yf;
HFC-32 and HFC-1234yf;
HFC-125 and HFC-1234yf;
HFC-32, HFC-125, and HFC-1234yf;
HFC-32, HFC-134a, and HFC-1234yf;
DME and HFC-1234yf;
HFC-152a and HFC-1234yf;
HFC-152a, HFC-134a, and HFC-1234yf;
HFC-152a, n-butane, and HFC-1234yf;
HFC-134a, propane, and HFC-1234yf;
HFC-125, HFC-152a, and HFC-1234yf;
HFC-125, HFC-134a, and HFC-1234yf;
HFC-32, HFC-1234ze, and HFC-1234yf;
HFC-125, HFC-1234ze, and HFC-1234yf;
HFC-32, HFC-1234ze, HFC-1234yf, and CF3I;
HFC-134a, HFC-1234ze, and HFC-1234yf;
HFC-134a and HFC-1234ze;
HFC-32 and HFC-1234ze;
HFC-125 and HFC-1234ze;
HFC-32, HFC-125, and HFC-1234ze;
HFC-32, HFC-134a, and HFC-1234ze;
DME and HFC-1234ze;
HFC-152a and HFC-1234ze;
HFC-152a, HFC-134a, and HFC-1234ze;
HFC-152a, n-butane, and HFC-1234ze;
HFC-134a, propane, and HFC-1234ze;
HFC-125, HFC-152a, and HFC-1234ze; or
HFC-125, HFC-134a, and HFC-1234ze.
Automobile air conditioning systems with and without an intermediate heat exchanger are tested to determine if an improvement is seen with the IHX. The working fluid is a blend of 95% by weight HFC-1225ye and 5% by weight of HFC-32. Each system has a condenser, evaporator, compressor and a thermal expansion device. The ambient air temperature is 30° C. at the evaporator and the condenser inlets. Tests are performed for 2 compressor speeds, 1000 and 2000 rpm, and for 3 vehicle speeds: 25, 30, and 36 km/h. The volumetric flow rate of air on the evaporator is 380 m3/h.
The cooling capacity for the system with an IHX shows an increase of 4 to 7% as compared to the system with no IHX. The COP also shows an increase of 2.5 to 4% for the system with the IHX as compared to a system with no IHX.
Cooling performance is calculated for HFC-134a and HFC-1234yf both with and without an IHX. The conditions used are as follows:
The data illustrating relative performance is shown in TABLE 5.
The data above demonstrate an unexpected level of improvement in energy efficiency (COP) and cooling capacity for the fluoroolefin (HFC-1234yf) with the IHX, as compared to that gained by HFC-134a with the IHX. In particular, COP is increased by 7.67% and cooling capacity is increased by 7.50%.
It should be noted that the subcool difference arises from the differences in molecular weight, liquid density and liquid heat capacity for HFC-1234yf as compared to HFC-134a. Based on these parameters it is estimated that there would be a difference in subcool achieved with the different compounds. When the HFC-134a subcool is set to 5° C., the corresponding subcool for HFC-1234yf is calculated to be 5.8° C.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/US2007/025675 | Dec 2007 | US | national |
This application is a continuation-in-part of and claims the priority benefit of pending U.S. patent application Ser. No. 12/119,023, filed May 12, 2008, which claims the priority benefit of U.S. Provisional Application No. 60/928,826, filed May 11, 2007, U.S. Provisional Application No. 60/988,562, filed Nov. 16, 2007 and PCT Application No. U.S. 07/25675, filed Dec. 17, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60928826 | May 2007 | US | |
| 60988562 | Nov 2007 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12119023 | May 2008 | US |
| Child | 13207557 | US |
