(12) Ulllted States Patent
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`Novak et al.
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`(10) Patent N0.:
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`(45) Date of Patent:
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`US006176102B1
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`US 6,176,102 B1
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`Jan. 23, 2001
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`(54) METHOD FOR PROVIDING
`REFRIGERATION
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`(56)
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`References Cited
`U s PATENT DOCUMENTS
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`(75)
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`( * ) Notice:
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`Inventors: Richard A. Novak; Gary D. Lang,
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`both of Naperville, IL (US); Arun
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`Aeharya, East Amherst, NY(Us);
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`John Henri Royal, Grand Island, NY
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`(US); Mohammad Abdul'Am
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`Rashad’B“ffa1°’NY(US)
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`(73) Assignee: Praxair Technology, Inc., Danbury, CT
`(US)
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`Under 35 U.S.C. 154(b), the term of this
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`parent Shall be extended for 0 days.
`(21) Appl.NO.: 09/222,812
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`Filed:
`Dec. 30, 1998
`(22)
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`Int. Cl.7 ...................................................... .. F25B 7/00
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`(51)
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`(52) U.S. Cl.
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`................................ .. 62/612; 62/114; 62/613
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`.................. .. 62/114X
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`62/114 X
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`§
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`62i114 X
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`62/114
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`d
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`7/1995 Doering et al.
`5,429,760 *
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`9/1996 Rothfleisch
`5,551,255 *
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`7/1997 Gage etral.
`5,650,089 *
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`: 3/ %’1‘“51:1 it a1~
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`5,792,381 *
`8i1998 Guug 6 ai
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`5,822,996 * 10/1998 sen';i";;,I‘;i.... N
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`* cited by examiner
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`Primary Examiner—William Doerrler
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`Assismm Exami”er—ChenjWen -Hang
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`(74) Attorney, Agent, or FLrm—Stanley Ktorides
`ABSTRACT
`57
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`( )A
`1
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`met o
`or proV1 1ng re rigeration suc as to an msu ate
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`enclosure wherein a defined multicomponent refrigerant
`fluid undergoes a phase change coupled with Joule-
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`Tnornson expansion to generate refrigeration over a Wide
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`temperature range which may comprise from ambient to low
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`rernnerarnreer
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`(58) Field of Search ............................. .. 62/114, 612, 335
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`33 Claims, 4 Drawing Sheets
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`Page 1 of 12
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`Arkema Exhibit 1016
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`Arkema Exhibit 1016
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`U.S. Patent
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`Jan. 23, 2001
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`Sheet 1 of 4
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`US 6,176,102 B1
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`U.S. Patent
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`Jan. 23, 2001
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`Sheet 2 of 4
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`US 6,176,102 B1
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`97x/'
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`U.S. Patent
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`Jan. 23, 2001
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`Sheet 3 of 4
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`US 6,176,102 B1
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`*3”
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`U.S. Patent
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`Jan. 23, 2001
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`Sheet 4 of 4
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`US 6,176,102 B1
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`US 6,176,102 B1
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`2
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`As used herein the term “zeotropic” means characterized
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`by a smooth temperature change accompanying a phase
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`change.
`As used herein the term “subcooling” means cooling a
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`liquid to be at a temperature lower than that liquid’s satu-
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`ration temperature for the existing pressure.
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`As used herein the term “low temperature” means a
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`temperature of 250° K or less, preferably a temperature of
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`200° K or less.
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`As used herein the term “refrigeration” means the capa-
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`bility to reject heat from a subambient temperature system to
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`the surrounding atmosphere.
`As used herein the term “variable load refrigerant” means
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`a mixture of two or more components in proportions such
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`that
`the liquid phase of those components undergoes a
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`continuous and increasing temperature change between the
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`bubble point and the dew point of the mixture. The bubble
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`point of the mixture is the temperature, at a given pressure,
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`wherein the mixture is all in the liquid phase but addition of
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`heat will initiate formation of a vapor phase in equilibrium
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`with the liquid phase. The dew point of the mixture is the
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`temperature, at a given pressure, wherein the mixture is all
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`in the vapor phase but extraction of heat will
`initiate
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`formation of a liquid phase in equilibrium with the vapor
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`phase. Hence, the temperature region between the bubble
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`point and the dew point of the mixture is the region wherein
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`both liquid and vapor phases coexist in equilibrium. In the
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`practice of this invention the temperature differences
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`between the bubble point and the dew point for the variable
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`load refrigerant is at least 10° K, preferably at least 20° K
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`and most preferably at least 50° K.
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`As used herein the term “fluorocarbon” means one of the
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`following:
`tetrafluoromethane (CF4), perfluoroethane
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`(CZF6), perfluoropropane (C3F8) perfluorobutane (C4F1O),
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`perfluoropentane (C5F12), perfluoroethene (C2F4), perfluo-
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`ropropene (C3F12), perfluorobutene (C4F8), perfluoropen-
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`tene (C5F10), hexafluorocyclopropane (cyclo-C3F6) and
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`octafluorocyclobutane (cyclo-C4F8).
`As used herein the term “hydrofluorocarbon” means one
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`of the following:
`fluoroform (CHF3), pentafluoroethane
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`(CZHFS),
`tetrafluoroethane (C2H2F4), heptafluoropropane
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`(C3HF7), hexafluoropropane (C3H2F6), pentafluoropropane
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`(C3H3F5),
`tetrafluoropropane (C3H4F4), nonafluorobutane
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`(C4HF9), octafluorobutane (C4H2F8), undecafluoropentane
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`(CSHF11), methyl
`fluoride (CH3F), difluoromethane
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`(CHZFZ), ethyl fluoride (C2H5F), difluoroethane (C2H4F2),
`trifluoroethane (C2H3F3), difluoroethene (C2H2F2), trifluo-
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`roethene (CZHF3), fluoroethene (C2H3F), pentafluoropro-
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`pene (C3HF5),
`tetrafluoropropene (C3H2F4),
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`pene (C3H3F3), difluoropropene (C3H4F2),
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`heptafluorobutene (C4HF7), hexafluorobutene (C 4H2F6)
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`and nonafluoropentene (CSHFQ).
`As used herein the term “fluoroether” means one of the
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`following:
`trifluoromethyoxy-perfluoromethane (CF3-O-
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`CF3), difluoromethoxy-perfluoromethane (CHF2-O-CF3),
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`fluoromethoxy-perfluoromethane (CH2F-O-CF3),
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`difluoromethoxy-difluoromethane (CHF2-O-CHF2),
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`difluoromethoxy-perfluoroethane (CHF2-O-CZF5),
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`difluoromethoxy-1,2,2,2-tetrafluoroethane (CHF2-O-
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`C2Hf4), difluoromethoxy-1,1,2,2-tetrafluoroethane (CHF2-
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`O-CZHF4), perfluoroethoxy-fluoromethane (CZF5-O-CH2F),
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`perfluoromethoxy-1,1,2-trifluoroethane (CF3-O-C2H2F3),
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`perfluoromethoxy-1,2,2-trifluoroethane (CF30-CZHZF3),
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`cyclo-1,1,2,2-tetrafluoropropylether (cyclo-C3H2F4-O-)
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`cyclo-1, 1,3,3-tetrafluoropropylether (cyclo-C3H2F4-O-),
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`perfluoromethoxy-1,1,2,2-tetrafluoroethane (CF3-O-
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`CZHF4), cyclo-1,1,2,3,3-pentafluoropropylether (cyclo-
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`15
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`1
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`METHOD FOR PROVIDING
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`REFRIGERATION
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`Technical Field
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`This invention relates generally to refrigeration systems
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`and is particularly advantageous for providing refrigeration
`to an insulated enclosure.
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`Background Art
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`The provision of refrigeration, such as for the cooling
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`and/or freezing of foods or pharmaceuticals, is typically
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`carried out using a mechanical refrigeration system wherein
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`a refrigerant such as ammonia or a freon is employed in a
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`vapor compression cycle. Such systems are effective for
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`providing refrigeration at relatively high temperature levels
`but to effectively achieve low level temperature refrigeration
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`there generally is required vacuum operation and/or cascad-
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`ing which increases both capital and operating costs.
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`One method for more effectively providing refrigeration
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`at low temperature levels is to use an expendable cryogenic
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`liquid, such as liquid nitrogen, either separately or in con-
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`junction with a mechanical refrigeration system, to provide
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`the requisite low level refrigeration. However, such systems,
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`while effective, are expensive because of the loss of, and
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`therefore the need for continued replacement of, the cryo-
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`genic liquid.
`Accordingly, it is an object of this invention to provide
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`a method for providing refrigeration, such as to a heat
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`exchanger or to an insulated enclosure, which can be used to
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`effectively provide such refrigeration, when needed, at a low
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`temperature.
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`SUMMARY OF THE INVENTION
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`The above and other obj ects, which will become apparent
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`to those skilled in the art upon a reading of this disclosure,
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`are attained by the present invention which is:
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`A method for providing refrigeration comprising:
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`(A) compressing a multicomponent refrigerant fluid com-
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`prising at least one component from the group consist-
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`ing of fluorocarbons, hydrofluorocarbons and fluoroet-
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`hers and at
`least one component from the group
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`consisting of fluorocarbons, hydrofluorocarbons, fluo-
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`roethers and atmospheric gases;
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`(B) cooling and at least partially condensing the com-
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`pressed multicomponent refrigerant fluid;
`(C) expanding the at least partially condensed multicom-
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`ponent refrigerant fluid to generate refrigeration; and
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`(D) warming and at least partially vaporizing the refrig-
`eration bearing multicomponent refrigerant fluid and
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`employing refrigeration from the multicomponent
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`refrigerant fluid in an enclosure.
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`As used herein the term “non-toxic” means not posing an
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`acute or chronic hazard when handled in accordance with
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`acceptable exposure limits. As used herein the term “non-
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`flammable” means either having no flash point or a very high
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`flash point of at least 600°0K.
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`As used herein the term “on-ozone-depleting” means
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`having zero-ozone depleting potential,
`i.e. having no
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`chlorine, bromine or iodine atoms.
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`As used herein the term “normal boiling point” means the
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`boiling temperature at 1 standard atmosphere pressure, i.e.
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`14.696 pounds per square inch absolute.
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`As used herein the term “indirect heat exchange” means
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`the bringing of fluids into heat exchange relation without
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`any physical contact or intermixing of the fluids with each
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`other.
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`As used herein the term “expansion” means to effect a
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`reduction in pressure.
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`Page 6 of 12
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`Page 6 of 12
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`US 6,176,102 B1
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`3
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`C3H5-O-), perfluoromethoxy-perfluoroacetone (CF3-O-
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`CF2-O-CF3), perfluoromethoxy-perfluoroethane (CF3-O-
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`C2F5), perfluoromethoxy-1,2,2,2-tetrafluoroethane (CF3-O-
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`CZHF4), perfluoromethoxy-2,2,2-trifluoroethane (CF3-O-
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`CZHZF3), cyclo-perfluoromethoxy-perfluoroacetone (cyclo-
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`CF2-O-CF2-O-CF2-) and cyclo-perfluoropropylether (cyclo-
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`C3F6-O).
`As used herein the term “atmospheric gas” means one of
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`the following: nitrogen (N2), argon (Ar), krypton (Kr),
`xenon (Xe), neon (Ne), carbon dioxide (CO2), oxygen (02)
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`and helium (He).
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`As used herein the term “low-ozone-depleting” means
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`having an ozone depleting potential less than 0.15 as defined
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`by the Montreal Protocol convention wherein dichlorofluo-
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`romethane (CCl2F2) has an ozone depleting potential of 1.0.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`FIG. 1 is a schematic flow diagram of one preferred
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`embodiment of the multicomponent refrigerant refrigeration
`system of this invention.
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`FIG. 2 is a schematic flow diagram of another preferred
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`embodiment of the multicomponent refrigerant refrigeration
`system of this invention.
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`FIG. 3 is a schematic flow diagram of another preferred
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`embodiment of the invention wherein multiple level refrig-
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`eration is provided.
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`FIG. 4 is a schematic flow diagram of another preferred
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`embodiment of the invention wherein multiple level refrig-
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`eration is provided and there is more than one phase sepa-
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`ration.
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`FIG. 5 is a schematic flow diagram of another preferred
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`embodiment of the invention for use with multiple enclo-
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`sures.
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`DETAILED DESCRIPTON
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`The invention comprises, in general, the use of a defined
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`zeotropic mixed refrigerant to efliciently provide refrigera-
`tion over a large temperature range, such as from ambient
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`temperature to a low temperature. The refrigeration may be
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`employed to provide refrigeration directly or indirectly to
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`one or more, preferably insulated, enclosures. The refrig-
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`eration may be used to cool, i.e. cool and/or freeze, articles
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`such as food or pharmaceuticals. Such refrigeration can be
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`effectively employed without the need for employing com-
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`plicated vacuum operation.
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`The invention may be used to provide refrigeration
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`required for cooling and/or freezing of food and pharma-
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`ceutical products, such as air make-up systems, cold room
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`storage, blast freezers, and freezer Applications convention-
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`ally employing mechanical freezers or cryogenic freezers.
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`The invention may be used to provide refrigeration for all
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`freezer types such as blast room,
`tunnel (stationary or
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`conveyor), multi-tier, spiral belt, fluidized bed, immersion,
`plate and contact belt freezers. The invention may also be
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`used for cooling of transport containers, freeze-drying of
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`foods or pharmaceuticals, dry ice production, subcooling of
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`refrigerants, vapor condensation,
`thermal energy storage
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`systems and cooling of superconductors in generators,
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`motors or transmission lines. The invention may also be
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`used for the production, storage and/or distribution of dry
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`ice.
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`The multicomponent refrigerant fluid useful in the prac-
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`tice of this invention comprises at least one component from
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`the group consisting of fluorocarbons, hydrofluorocarbons
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`and fluoroethers and at least one component from the group
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`10
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`15
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`25
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`30
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`35
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`45
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`50
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`55
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`60
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`65
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`4
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`consisting of fluorocarbons, hydrofluorocarbons, fluoroet-
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`hers and atmospheric gases in order to provide the required
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`refrigeration at each temperature. The choice of refrigerant
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`components will depend on the refrigeration load versus
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`temperature for the particular process application. Suitable
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`components will be chosen depending upon their normal
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`boiling points, latent heat, and flammability, toxicity, and
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`ozone-depletion potential.
`One preferable embodiment of the multicomponent
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`refrigerant fluid useful
`in the practice of this invention
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`comprises at least two components from the group consist-
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`ing of fluorocarbons, hydrofluorocarbons and fluoroethers.
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`Another preferable embodiment of the multicomponent
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`refrigerant fluid useful
`in the practice of this invention
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`comprises at least one component from the group consisting
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`of fluorocarbons, hydrofluorocarbons and fluoroethers, and
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`at least one atmospheric gas.
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`Another preferable embodiment of the multicomponent
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`refrigerant fluid useful
`in the practice of this invention
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`comprises at least one fluoroether and at least one compo-
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`from the group consisting of fluorocarbons,
`nent
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`hydrofluorocarbons, fluoroethers and atmospheric gases.
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`In one preferred embodiment the multicomponent refrig-
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`erant fluid consists solely of fluorocarbons. In another pre-
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`ferred embodiment
`the multicomponent refrigerant fluid
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`consists solely of fluorocarbons and hydrofluorocarbons. In
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`another preferred embodiment the multicomponent refrig-
`erant fluid consists solely of fluorocarbons and atmospheric
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`gases. In another preferred embodiment the multicomponent
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`refrigerant fluid consists solely of fluorocarbons, hydrofluo-
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`rocarbons and fluoroethers. In another preferred embodi-
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`ment the multicomponent refrigerant fluid consists solely of
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`fluorocarbons, fluoroethers and atmospheric gases.
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`The multicomponent refrigerant fluid useful in the prac-
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`tice of this invention may contain other components such as
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`hydrochlorofluorocarbons and/or hydrocarbons. Preferably,
`the multicomponent refrigerant fluid contains no hydrochlo-
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`rofluorocarbons. In another preferred embodiment of the
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`invention the multicomponent refrigerant fluid contains no
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`hydrocarbons. Most preferably the multicomponent refrig-
`erant fluid contains neither hydrochlorofluorocarbons nor
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`hydrocarbons. Most preferably the multicomponent refrig-
`erant fluid is non-toxic, non-flammable and non-ozone-
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`depleting and most preferably every component of the
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`multicomponent refrigerant fluid is either a fluorocarbon,
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`hydrofluorocarbon, fluoroether or atmospheric gas.
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`The invention is particularly advantageous for use in
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`efliciently reaching low temperatures from ambient tem-
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`peratures. Tables 1-6 list preferred examples of multicom-
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`ponent refrigerant fluid mixtures useful in the practice of this
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`invention. The concentration ranges given in the Tables are
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`in mole percent. The examples shown in Tables 1-5 are
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`particularly useful in the temperature range of from 175° K
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`to 250° K and the examples shown in Table 6 are particularly
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`useful in the temperature range of from 80° K to 175° K.
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`COMPONENT
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`TABLE 1
`
`CONCENTRATION RANGE
`
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`
`C5F12
`
`C4F1D
`
`C3F8
`
`C2F5
`
`CE,
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`5-35
`0-25
`10-50
`10-60
`0-25
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`Page 7 of 12
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`Page 7 of 12
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`US 6,176,102 B1
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`COMPONENT
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`
`
`TABLE 2
`
`CONCENTRATION RANGE
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`C5F12
`
`C3H3F5
`
`C3F8
`
`CHF3
`
`CE,
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`5-35
`
`0-25
`
`10-50
`
`10-60
`
`0-25
`
`
`COMPONENT
`
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`
`TABLE 3
`
`CONCENTRATION RANGE
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`C3H3F5
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`C3H3F5
`
`C2H2F4
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`CZHFS
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`C2F5
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`CE,
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`COMPONENT
`
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`CHF2—O—C2HF4
`C4F1D
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`CF3—O—CHF2
`
`CF3—O—CF3
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`C2F5
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`CE,
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`5-35
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`0-25
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`5-20
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`5-20
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`10-60
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`0-25
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`TABLE 4
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`CONCENTRATION RANGE
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`5-35
`
`0-25
`
`10-25
`
`0-20
`
`10-60
`
`0-25
`
`
`COMPONENT
`
`
`CHF2—O—C2HF4
`C3H2F5
`
`CF3—O—CHF2
`CHF3
`
`CE,
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`TABLE 5
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`CONCENTRATION RANGE
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`5-35
`
`0-25
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`10-50
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`10-60
`
`0-25
`
`
`COMPONENT
`
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`TABLE 6
`
`CONCENTRATION RANGE
`
`
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`C5F12
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`C4Fm
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`C3F8
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`C2F5
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`CE,
`Ar
`
`
`N2
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`
`5-25
`
`0-15
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`10-40
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`0-30
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`10-50
`0-40
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`
`10-80
`
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`The invention is especially useful for providing refrigera-
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`tion over a wide temperature range, particularly one which
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`encompasses low temperatures. In a preferred embodiment
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`of the invention each of the two or more components of the
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`refrigerant mixture has a normal boiling point which differs
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`by at least 5 degrees Kelvin, more preferably by at least 10
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`degrees Kelvin, and most preferably by at least 20 degrees
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`Kelvin, from the normal boiling point of every other com-
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`ponent in that refrigerant mixture. This enhances the effec-
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`tiveness of providing refrigeration over a wide temperature
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`range, particularly one which encompasses cryogenic tem-
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`peratures. In a particularly preferred embodiment of the
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`invention, the normal boiling point of the highest boiling
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`component of the multicomponent refrigerant fluid is at least
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`50° K, preferably at least 100° K, most preferably at least
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`Page 8 of 12
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`6
`200° K, greater than the normal boiling point of the lowest
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`boiling component of the multicomponent refrigerant fluid.
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`The components and their concentrations which make up
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`the multicomponent refrigerant fluid useful in the practice of
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`this invention are such as to form a variable load multicom-
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`ponent refrigerant fluid and preferably maintain such a
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`variable load characteristic throughout the whole tempera-
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`ture range of the method of the invention. This markedly
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`enhances the efficiency with which the refrigeration can be
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`generated and utilized over such a wide temperature range.
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`The defined preferred group of components has an added
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`benefit in that they can be used to form fluid mixtures which
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`are non-toxic, non-flammable and low or non-ozone-
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`depleting. This provides additional advantages over conven-
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`tional refrigerants which typically are toxic, flammable
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`and/or ozone-depleting.
`One preferred variable load multicomponent refrigerant
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`fluid useful in the practice of this invention which is non-
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`toxic, non-flammable and non-ozone-depleting comprises
`two or more components from the group consisting of
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`CSF12, CHF2-O-CZHF4, C4HF9, C3H3F5, CZF5-O-CHZF,
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`C3H2F6, CHF2-O-CHF2, C4F10, CF3-O-CZHZF3, C3HF7,
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`CHZF-O-CF3, CZHZF4, CHF2-O-CF3, C3F8, CZHFS, CF3-O-
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`CF3, C2F6, CHF3, CF4, 02, Ar, N2, Ne and He.
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`The defined multicomponent refrigerant
`fluid of the
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`invention is zeotropic. The components have different boil-
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`ing points to span the entire temperature range of interest so
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`that desired very low temperatures, such as cryogenic
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`temperatures, can be achieved efficiently and generally with
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`only a single stage of compression and without the need for
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`vacuum operation. This contrasts with conventional refrig-
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`erants used to provide refrigeration which are composed of
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`single components or blends of two or three components
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`formulated to behave like a single component, i.e. narrow-
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`boiling azeotropic or near-azeotropic blends.
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`The invention is employed to provide refrigeration to an
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`enclosure, particularly an insulated enclosure. Such insu-
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`lated enclosure used with the invention is typically a freezer,
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`cold storage container or cold room. It need not be com-
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`pletely closed to the ambient atmosphere. Any insulation
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`means which is effective in reducing heat leak into the
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`container or freezer may be used. Under some limited
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`circumstances, it may be that the subambient temperature
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`facility, such as a cold processing room, is not insulated or
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`is only partially insulated.
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`The invention will be described in greater detail with
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`reference to the Drawings. Referring now to FIG. 1, multi-
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`component refrigerant fluid 50 is compressed to a pressure
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`generally within the range of from 30 to 1000 pounds per
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`square inch absolute (psia), preferably from 100 to 600 psia,
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`by passage through compressor 51 and resulting compressed
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`multicomponent refrigerant fluid 52 is cooled of the heat of
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`compression by passage through cooler 53. Resulting cooled
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`multicomponent refrigerant fluid 54 is further cooled and at
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`least partially, preferably completely, condensed by passage
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`through heat exchanger 55. Resulting at
`least partially
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`condensed multicomponent refrigerant fluid 56 is expanded
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`through valve 57 to a pressure generally within the range of
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`from 5 to 100 psia, preferably from 15 to 100 psia, thereby
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`generating refrigeration by the Joule-Thomson effect, i.e.
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`lowering of the fluid temperature due to pressure reduction
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`at constant enthalpy. The expansion of the multicomponent
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`refrigerant fluid through valve 57 may also cause some of
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`the refrigerant
`fluid to vaporize. The pressure levels
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`employed for the high pressure refrigerant of stream 52 and
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`the low pressure refrigerant of stream 58, and the compo-
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`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`Page 8 of 12
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`

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`US 6,176,102 B1
`
`
`
`7
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`sition of the refrigerant, are selected to achieve the desired
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`temperature levels at acceptable cost and efficiency.
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`Refrigeration bearing multicomponent refrigerant fluid 58
`is then warmed and vaporized by passage through heat
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`exchanger 55 and then passed as stream 50 to compressor 51
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`and the cycle begins anew. The warming and vaporization of
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`the refrigeration bearing multicomponent refrigerant fluid in
`heat exchanger 55 serves to cool by indirect heat exchange
`
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`refrigerant fluid 54, as was previously described, and also to
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`cool by indirect heat exchange insulated enclosure atmo-
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`sphere fluid, as will now be described.
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`A portion of the atmosphere fluid, which is typically air
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`but may be another fluid such as nitrogen, carbon dioxide or
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`any other suitable fluid, is withdrawn from insulated enclo-
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`sure 59 in stream 60 and passed through separator 61 to
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`remove any entrained ice. Separator 61 may be a centrifugal
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`separator, a filter, or any other suitable separation means.
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`Ice-free insulated enclosure atmosphere fluid 62 then flows
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`through blower 63 which produces pressurized gas stream
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`64, generally at a pressure within the range of from 15 to 100
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`psia, preferably from 16 to 20 psia, and then through
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`purification unit 25. If necessary, additional make up gas
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`may be provided, such as is shown in FIG. 1 by stream 68,
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`compressed in blower 69, passed in stream 70 through
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`purification unit 71 and then as stream 72 combined with
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`stream 64 to form stream 65. Purification units 25 and 71
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`may be molecular sieve, adsorption bed, or any other
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`suitable means for removing high boiling components such
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`as moisture or carbon dioxide. Alternatively, all of the fluid
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`to be refrigerated may be obtained by means of stream 68
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`such that fluid removed from enclosure 59 is not recircu-
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`lated.
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`Fluid 65 is then passed through heat exchanger 55
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`wherein it
`is cooled by indirect heat exchange with the
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`aforesaid warming and vaporizing multicomponent refrig-
`erant fluid resulting in the production of refrigerated insu-
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`lated enclosure atmosphere fluid 66 which typically has a
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`temperature less than 250° K and generally will have a
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`temperature within the range of from 100° K to 250° K. The
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`cooling of the atmosphere or process fluid may include
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`partial or complete liquefaction of the fluid, for example, the
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`production of liquid air. The refrigerated fluid 66 is then
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`passed into insulated enclosure 59 wherein the refrigeration
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`within fluid 66 is employed. If desired, insulated enclosure
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`59 may be equipped with a fan 67 or other atmosphere
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`circulation device to assist in more evenly distributing the
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`refrigeration within the enclosure and for enhancing the heat
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`transfer characteristics of the refrigerated fluid.
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`FIG. 2 illustrates another embodiment of the invention
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`wherein the heat exchange between the warming multicom-
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`ponent refrigerant fluid and the cooling insulated enclosure
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`atmosphere fluid occurs within the insulated enclosure.
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`Referring now to FIG. 2, multicomponent refrigerant fluid
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`30 is compressed to a pressure generally within the range of
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`from 30 to 1000 psia, preferably from 100 to 600 psia, by
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`passage through compressor 31, and resulting compressed
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`multicomponent refrigerant fluid 32 is cooled of the heat of
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`compression by passage through cooler 33. Resulting cooled
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`multicomponent refrigerant fluid 34 is further cooled and at
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`least partially, preferably completely, condensed by passage
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`through heat exchanger 35. Resulting at
`least partially
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`condensed multicomponent refrigerant fluid 36 is expanded
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`through valve 37 to a pressure within the range of from 5 to
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`100 psia, preferably 15 to 100 psia,
`thereby generating
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`refrigeration by the Joule-Thomson effect. Refrigeration
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`bearing multicomponent refrigerant fluid 38, which may be
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`a two-phase stream, is then passed into insulated enclosure
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`40.
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`5
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`8
`The passage of refrigeration bearing multicomponent
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`refrigerant fluid within insulated enclosure 40 includes pas-
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`sage through heat exchange coils 39 or other suitable heat
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`exchange means wherein the refrigeration bearing multi-
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`component refrigerant fluid is warmed and vaporized by
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`indirect heat exchange with the insulated enclosure atmo-
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`sphere fluid. If desired, the refrigeration bearing refrigerant
`fluid may be injected into the enclosure so that the heat
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`exchange with the insulated enclosure atmosphere fluid is by
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`direct heat exchange. The resulting refrigerated insulated
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`enclosure atmosphere fluid is then employed throughout
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`insulated enclosure 40, preferably with the assistance of
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`fluid flow enhancement means such as fan 42,
`thereby
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`providing refrigeration to the insulated enclosure. Resulting
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`warmed multicomponent