(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
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`8 December 2011 (08.12.2011) (10) International Publication Number
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`(43) International Publication Date
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`WO 2011/150940 A1
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`(51)
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`(21)
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`International Patent Classification:
`C09K 5/04 (2006.01)
`F253 9/00 (2006.01)
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`(81)
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`International Application Number:
`PCT/DK201 1/050193
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`(22)
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`International Filing Date:
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`(25)
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`(26)
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`(30)
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`(71)
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`(72)
`(75)
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`Filing Language:
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`Publication Language:
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`1 June 2011 (01.06.2011)
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`English
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`English
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`Priority Data:
`PA 2010 70244
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`3 June 2010 (03.06.2010)
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`DK
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`Applicant (for all designated States except US): ARC-
`TIKO A/S [DK/DK]; c/o Lars Ole Mailer Jensen, Lam-
`meijordsvej 5, DK-6715 Esbjerg N (DK).
`
`Inventors; and
`Inventors/Applicants (for US only): Jensen, Lars, Ole
`[DK/DK];
`Idraets Alle 47, DK—6710 Esbjerg v (DK).
`Nielsen. Hans Jorgen [DIQDK]; Strynavej 36, DK-6710
`Esbjerg V (DK). Svendsen, Tove, Taekker [DK/DK];
`Jagtvaenget 78, DK-6710 Esbjerg V (DK).
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`(74)
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`Agent: PATRADE A/S; Fredens Torv 3A, DK-8000
`Aarhus (DK).
`
`Designated States (unless otherwise indicated, for evety
`kind ofnational protection available): AE, AG, AL, AM,
`A0, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ,
`CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO,
`DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT,
`HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP,
`KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD,
`ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI,
`NO, NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD,
`SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, TN, TR,
`TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW.
`
`(84)
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`Designated States (unless otherwise indicated, for every
`kind ofregional protection available): ARIPO (BW, GH,
`GM, KE, LR, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG,
`ZM, ZVV), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ,
`TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK,
`EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, rr, LT, LU,
`LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK,
`SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ,
`GW, ML, MR, NE, SN, TD, TG).
`Published:
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`with international search report (Art. 21(3))
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`(54) Title: A COOLlNG SYSTEM AND A NON-AZEOTROPIC REFRIGERANT MIXTURE OF ENVIRONMENTALLY
`FRIENDLY REFRIGERANTS
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`(57) Abstract: The present invention relates to a
`cooling system and a non—azeotropic refrigerant
`mixture of environmentally friendly refrigerants
`comprises a first main group of refrigerants, which
`first main group comprises at least a mixture of the
`following refrigerants, R600, Butane, R600a,
`Isobutane, and R1150, Etylene. The non-azeotrop-
`ic mixture of refrigerants fiirther comprise at least
`a second minor group of refrigerants, in which mi-
`nor group of refrigerants belongs to a group of en-
`vironmentally friendly refrigerants, to which minor
`group belongs at least one refrigerant d: which re-
`frigerant d: has a nature boiling point below
`-75°C. Here by a highly effective cooling system
`can be achieved that can be used eg. in ultra low
`temperature cooling systems.
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`
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`WO 2011/150940
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`PCT/DK2011/050193
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`[A cooling system and a non-azeotropic refrigerant mixture of environmentally
`
`friendly refrigerants]
`
`Field of the Invention
`
`The present invention relates to a cooling system comprising at least one compressor,
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`at least one condenser, at least a first heat exchanger, at least one flow restriction and
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`at least one evaporator, which cooling system comprises a first non-azeotropic mixture
`
`of refrigerants, which non-azeotropic mixture comprises at least the following main
`
`components, R600, Butane, R600a, lsobutane and R1150, Etylene, which main com-
`
`ponents belongs to a group of environmentally friendly refrigerants.
`
`The present invention fiirther relates to a non—azeotropic refrigerant mixture of envi—
`
`ronmentally friendly refrigerants comprises a first main group of refrigerants, which
`
`first main group comprises at least a mixture of the following refrigerants, R600, Bu-
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`tane, R600a, Isobutane, and R1150, Etylene.
`
`Background of the Invention
`
`US 2008/0302116 concern a refiigerating control system using a non—azeotropic re—
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`fiigerant, on a single-stage type refrigerating system using non-azeotropic refrigerant,
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`composing with a compressor, a condenser, and an evaporator, heat exchanging be-
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`tween returned-refrigerant
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`from evaporator and high-pressure refrigerant
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`toward
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`evaporator, electromagnetic valves of capillary tubes as expansion valves of evaporator
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`are fully open, at moments of large load needed such as at starting up, the system is
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`controlled flux of rcfiigerant gas and pressure of it by closing them one by the other
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`corresponding to going down of interior room temperature. As the state of interior
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`room temperature is high and low boiling point constituent is not condensed, cooling
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`capability of high boiling point refiigerant performs in maximum.
`
`US 7624586 concerns refiigerant circuit for freezing device comprises non-azeotropic
`
`refrigerant mixture of pentafluoropropane, butane,
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`trifluoromethane and tetra-
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`fluoromenthane; or pentafluoropropane, butane, hexafluoroethane and tetrafluoromen—
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`thane. An object is to provide a freezing device in which a safely—treatable incombusti—
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`blc mixed refrigerant can be used and which can realize an extremely low temperature
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`of -85° C. or less in chamber by a simple structure. The freezing device comprises a
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`single refrigerant circuit in which the refrigerant discharged from a compressor is con-
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`densed and thereafter are evaporated to exert a cooling function and which allows heat
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`exchange between the evaporated refrigerant and the condensed refrigerant, wherein
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`there is introduced into the refrigerant circuit a non-azeotropic mixed refrigerant con-
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`taining R245fa, R600, R23 and R14; a non-azeotropic mixed refrigerant containing
`
`R245fa, R600, R116 and R14; a non-azeotropic mixed refrigerant containing R245fa,
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`R600, R508A and R14; or a non-azeotropic mixed refrigerant containing R245fa,
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`R600, R5088 and R14.
`
`US 7 299 653 concerns a refrigerator system using non-azeotropic refrigerant, and
`
`non-azeotropic refrigerant for very low temperature used for the system. A single-stage
`
`refrigerating system includes a compressor, a condenser, an evaporator, and a heat
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`exchanger for exchanging heat between a refrigerant in a path from the evaporator to
`
`the compressor and a refrigerant in another path from the condenser to the evaporator,
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`and a non-azeotropic refrigerant mixture used in the system. The refrigerant mixture is
`
`a combination of a refrigerant having a normal boiling point of approximately room
`
`temperature and a low-boiling-point refrigerant having a normal boiling point below -
`
`60° C. A dew point of the refrigerant mixture at a pressure in the condensing process
`
`after the compression is above room temperature. The boiling point is higher than the
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`dew point at a pressure in the lower-pressure region in a path from the evaporator to
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`the compressor. The combination may include butane or isobutane as the high-boiling-
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`point refrigerant component having a normal boiling point of approximately room tem-
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`perature and having a low evaporating pressure and ethane or ethylene as the low-
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`boiling—point refrigerant component suitable for achieving ultra—low temperature.
`
`US 6 495 061 concern refrigerant for providing ultra-low temperature. A mixed refrig-
`
`erant comprising one member selected from R-23, R—116 and a mixture thereof and
`
`one member selected from propane, butane and a mixture thereof. The mixed refriger-
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`ant allows cooling the inside of a freezer to a super low temperature, particularly to a
`
`temperature of -60° C. or lower, with a compressor of a conventional freezer. The
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`mixed refrigerant not only has a low boiling point similar to those of R—23 and R—116,
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`but also can be liquefied in a room temperature surrounding due to propane or butane
`
`contained therein, and fiirther has good miscibility with a lubricating oil or the like so
`
`that a freezer unit using the refrigerant is free from the problem of clogging therein.
`
`Additionally, the mixed refrigerant has no ability to deplete ozone and is significantly
`
`low with respect to greenhouse effect. The refrigerant can be liquefied by a pressure
`
`within the range of practical ability of a compressor in a room temperature surrounding
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`and allows achieving with ease a temperature inside a freezer of -60° C. or lower by
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`means of a freezer unit using one gas and one compressor.
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`EP 1 775 333 A1 concerns a freezing device in which a safely—treatable incombustible
`
`mixed refrigerant can be used and which can realize an extremely low temperature of -
`
`85A°C or less in chamber by a simple structure. The freezing device comprises a single
`
`refrigerant circuit in which the refrigerant discharged from a compressor is condensed
`
`and thereafter evaporated to exert a cooling fianction and which allows heat exchange
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`between the evaporated refrigerant and the condensed refrigerant, wherein there is in—
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`troduced into the refrigerant circuit a non-azeotropic mixed refrigerant containing
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`R245fa, R600, R23 and R14; a non-azeotropic mixed refrigerant containing R245fa,
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`R600, R116 and R14; a non-azeotropic mixed refrigerant containing R245fa, R600,
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`R508A and R14; or a non-azeotropic mixed refrigerant containing R245fa, R600,
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`R508B and R14.
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`EP 1 491 608 B1 concerns refrigerant mixture and refrigeration cycle apparatus using
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`the same. If a refrigerant mixture of carbon dioxide (R744) is used in a refrigeration
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`cycle apparatus, a pressure and a discharging temperature are increased. It is an object
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`of the present invention to solve these problems and to obtain more excellent charac—
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`teristics. A refrigerant mixture comprises carbon dioxide (R744) having non-azeotropic
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`properties and hydrocarbon refrigerant comprising one of propane, cyclopropane, iso-
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`butane and butane. If the hydrocarbon refrigerant is propane, the concentration of
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`R744 in the entire refrigerant mixture is 30% or lower by weight. If the hydrocarbon
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`refrigerant is cyclopropane, the concentration of R744 in the entire refrigerant mixture
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`is 40% or lower by weight. If the hydrocarbon refrigerant is isobutane, the concentra-
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`tion of R744 in the entire refrigerant mixture is 60% or lower by weight. If the hydro—
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`carbon refrigerant is butane, the concentration of R744 in the entire refrigerant mixture
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`is 70% or lower by weight. The refrigerant mixture is charged into a refrigeration cycle
`
`apparatus.
`
`JP2006000322588 concerns a_single stage type refrigerator system is composed of a
`
`heat exchanger exchanging heat between a refrigerant circulated from the compressor
`
`to a condenser, an evaporator and back to the compressor, and a refrigerant in a proc-
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`ess of reaching the evaporator from the condenser. The non-azeotropic refrigerant for
`
`use in the system is composed of the combination of a refrigerant having a standard
`
`boiling point near an ordinary temperature, and a refrigerant having a low standard
`
`boiling point of -60°C or lower. A dew point of the refrigerant at the pressure in a con—
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`densing process after compression is the ordinary temperature or higher, and the boil-
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`ing point at that pressure is not lower than a dew point at low pressure in a process of
`
`reaching the compressor from the evaporator. As the combination of the above refrig-
`
`erant components, butane or isobutane can be used as the refrigerant having a high
`
`boiling point near the room temperature and low steam pressure, and ethane, ethylene,
`
`or the like can be used as the refrigerant having a low boiling point suitable for ultra-
`
`low temperature.
`
`JP2007000277413 concerns a ternary non-azeotropic refrigerant for ultra-low tem-
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`perature service capable of offering service smoothly and stably without reconstructing
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`the refrigerant circulation line of a conventional single-step type refrigerating system
`
`for ultra-low temperature service (unitary refrigeration circuit).
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`The non-azeotropic refrigerant for ultra-low temperature service for use in a single-
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`step type refrigerating system contains a high boiling point gas (boiling point at Tbl), a
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`low boiling point gas (boiling point at Tb2), and an ultra-low boiling point gas (boiling
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`point at Tb3), wherein the boiling points of three sorts of gases meet the condition -
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`30
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`273°CSTb3S-l30°C<TB2<-200C < TBl <+60°C.
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`In the documents described above, the refrigerant mixtures contain refrigerants which
`
`are to be avoided because they have a very negative influence because of relative high
`
`ozone depletion potential or high global warming potential. None of the refrigerant
`
`mixtures that are described above can be described as a green mixture of refrigerants.
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`Many of the mixtures of course contain ammonia or carbon dioxide or other natural
`
`gasses which are environmentally friendly but the mixtures all contains at least small
`
`amounts of refrigerants which have to be avoided.
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`Object of the Invention
`
`It is the object of the pending application to achieve an environmentally friendly low
`
`temperature cooling system. It is a fithher object of the pending application to achieve
`
`a mixture of refrigerants for cooling systems where all the refrigerants contained in the
`
`mixture are environmentally friendly. A further object of the pending application is the
`
`use of the environmentally friendly refrigerant mixture.
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`Description of the Invention
`
`The object can be achieved by a system as described in the preamble to the claim 1 and
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`fithher modified by adding at least a refrigerant, which refrigerant belongs to a group
`
`of environmentally friendly refrigerants,
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`which refrigerant d: has a nature boiling
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`20
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`point below - 75°C.
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`Hereby it can be achieved that the mixture of refrigerant is a green mixture because all
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`gasses that are contained are environmentally friendly. With the mixture as described, it
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`is possible to achieve a low temperature cooling system. A cooling system that contains
`
`only green refrigeration components can be used and even if a leak occurs in the cool-
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`ing system and the refrigerant is leaking in to the nature, the refrigerant that is released
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`will be very environmentally friendly. Also in normal use of a cooling system also in a
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`service situation, it is much easier to exchange the refrigerant if it is allowed to let at
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`least smaller amount of the refrigerant flow out of a cooling system.
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`The second minor group of refrigerants can comprise at least one further refrigerant e:
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`which rcfrigcrant d: has a natural boiling point bclow — 140 OC. Hcrcby it can be
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`achieved that a relative low temperature so that the mixture of refrigerant can be used
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`in cooling systems that can achieve very low temperatures. It is possible with the low
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`natural low boiling point of the refrigerant d to achieve temperatures as low as - 90°C.
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`Even lower temperatures should be possible by changing the mixture so that more of
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`the low temperature boiling refrigerant is used.
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`The refrigeration system can comprise at least one compressor, which compressor has
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`a pressure outlet connected to a condenser, from which condenser the high pressure
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`refrigerant flows through a heat exchanger, in which heat exchanger the high pressure
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`refrigerant is cooled by low pressure cold refrigerant flowing back towards the suction
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`inlet at the compressor, from which heat exchanger the high pressure refrigerant flows
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`towards a flow restriction in form of a capillary tube, from which capillary tube the low
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`pressure refrigerant flows through an evaporator, from which evaporator the low pres-
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`sure refrigerant flows back through the heat exchanger to the suction inlet of the com—
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`pressor. Hereby a highly effective cooling system can be achieved that can be used e.g.
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`in ultra low temperature freezers. Another possibility for a cooling system is to use the
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`system in portable freezers in a temperature area of -80 °C. The cooling system can be
`
`used in upright low and ultra low temperature freezers. Further, it is possible to use the
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`cooling system in ultra low temperature chest freezers, can be used for laboratory or
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`pharmaceutical refrigerators and freezers. Another possibility is to form a cold store
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`room with the cooling system. This could e.g. be made in a container. In this way, it
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`should be able to achieve a highly effective container cooling system in which container
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`cooling system it is possible to achieve extremely low temperatures such as tempera-
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`tures ranging in the area -60 CC to -80 °C.
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`The cooling system can be a single compressor system especially designed for ultra low
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`temperature purposes. It should be possible with the single compressor system to
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`achieve low energy consumption, low noise, and low heat dissipation. E. g. the cooling
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`system could achieve -85°C and at the same time be equipped with a small footprint
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`ensuring easy access to all the different storage rooms that could be accessed from the
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`front of a freezing system.
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`In a possible embodiment for the invention the condenser can be coil formed, as many
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`different condensers could in fact be used. But specially by using a coil formcd con—
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`denser it is possible to avoid building up dust at the condenser and there is no need for
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`cleaning of the condenser unit as such. Even after years of operation, the coil formed
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`condenser will still be highly effective. Of course after many years it can be necessary
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`to clean the coil but that can easily be performed by pressured air and condenser will
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`operate as new again. This is highly effective compared to traditional condenser units
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`that are partly closed because they have a great surface for conducting most of the
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`heats to the air and may be blowing units are blowing air through a rather compact heat
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`exchanger that is very difficult to clean for dust and other kind of impurities that are
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`accumulated in the heating plates that are part of the condenser unit.
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`The evaporator can be formed in a number of parallel sections for shelves in a cooling
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`shrank.
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`In e.g. upright ultra low temperature freezers, it is important that the freezer
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`can be designed with a number of different sections which section could be accommo-
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`dated from the outside one by one. In order to achieve a rapid cooling inside one of the
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`rooms, it is very important that an evaporator is placed in each of the rooms. In that
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`way it can be achieved that the same constant temperature occurs in freezer storage.
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`By start up a refrigeration system the relative big evaporator which is divided in a
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`number of sections will result in a faster cooling down to the operational temperature,
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`this is rather important if the temperature which has to be reached is as low as -80 °C
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`or —90°C.
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`The object can be also be achieved by a mixture as described in the preamble to claim 6
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`and further modified by adding at least one refrigerant, which refrigerant belongs to a
`
`group of environmentally friendly refrigerants,: which refrigerant d: has a nature boiling
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`point below — 75°C.
`
`The new mixture of refrigerants can be used in many different cooling systems such as
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`low temperature cooling rooms for storage of medicine or other chemical substances
`
`typical in the temperature range from -40°C to -60°C. Another possibility is to use the
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`new mixture of refrigerant in mobile containers for achieving temperatures at —60°C in
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`the container. Further the composition of refrigerant can be used in all low temperature
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`freezers .
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`Also in many air condition systems the new mixture of refrigerant can be used. It
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`should be possible to built very compact air conditioning systems with relative small
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`evaporators by using relative low temperature evaporation of the refrigerant. The very
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`compact air condition systems could in fact be used in private homes but another pos-
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`sibility of using that refrigerant is in mobile air condition systems. Air condition is
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`widely used in the transportation area because air condition is now standard in most
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`cars, trucks and also farm machinery are today equipped with air condition. There Will
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`be an enormous market for new refrigerant compositions e.g. for car air condition sirn—
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`ply because the mostly used refrigerant in car air condition is R134A which at this mo—
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`ment is allowed but in the fiiture this particular refrigerant is most likely to be forbid-
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`den in Europe.
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`The minor group of refrigerants can comprise at least one further refrigerant e: which
`
`refrigerant d. has a natural boiling point below — 140°C. By adding a refrigerant with a
`
`natural boiling point that is very low, it is possible to achieve very low temperatures at
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`the evaporator and as such in the room that has to be cooled. By adding a refrigerant
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`with the very low natural boiling point it is possible to achieve a cooling system that
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`can achieve temperatures as low as -90 °C.
`
`The main group of refrigerants (a, b, c) can comprise more than 60% of the weight of
`
`the refrigerant mixture, which minor group of refrigerant (d, e) comprises less than 30
`
`% of the weight of the refrigerant mixture. The mixture of the refrigerants can of
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`course be changed so that the amount of the different refrigerants is adjusted independ-
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`ent of the actual use of the refrigerant.
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`The object of the pending application can be achieved by a system as described in the
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`preamble to the claim 9 and further modified by use of a non-azeotropic refrigerant
`
`mixture of environmentally friendly refrigerants in low temperature cooling systems.
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`As already mentioned the new refrigerant mixture can be widely used in cooling sys—
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`tems such as low temperature storage rooms, low temperature container cooling up—
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`right low temperature freezers, low temperature chest freezers and as already described
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`in all different aspects of air condition.
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`The non—azeotropic refrigerant mixture of environmentally friendly refrigerants can be
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`used in container cooling systems for achieving storage temperature in container below
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`— 600 C. Especially for containers that have been transported on lorries or on ships, it
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`can be very important to achieve very low temperatures inside the containers. If that
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`low temperature should be achieved by environmentally friendly refrigeration systems,
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`it is very important to use a refrigerant as described above.
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`Use of a non-azeotropic refrigerant mixture of environmental friendly refrigerants in a
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`low temperature storage, in which storage the temperature is below - 60°C. Especially
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`in low temperature storages, it can be important to use a green refrigerant composition.
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`Use of a non—azeotropic refrigerant mixture of environmentally friendly refrigerants as
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`described in the claims 6-8 in air condition systems. As already mentioned, the new
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`refrigerant can be used in air condition systems. The relative low temperature refriger-
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`ant could be used in air condition systems in aeroplanes because relative small evapora-
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`tors can be used.
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`Use of a non-azeotropic refrigerant mixture of environmentally friendly refrigerants as
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`described in the claims 6-8 in industrial applications such as cooling of computer sys-
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`tems. There is a growing demand for cooling computer systems. Typical servers are
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`placed in buildings that are cooled by air condition systems. But in the filture it could
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`be necessary to cool the computer racks directly by evaporators placed relatively close
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`to the heat producing components. Liquid cooling of central processing units could be
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`necessary if the processing speed should be further increased. In this situation, it could
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`be necessary to form a low temperature evaporator with thermal conductivity directly
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`to the central processing units in order to keep their temperatures relatively low. In
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`order to achieve that cooling, it is necessary in the fiJture to use only a green combina—
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`tion of refrigerants.
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`Description of the Drawings
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`Figure 1 shows a first possible embodiment of a cooling system.
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`Figure 2 shows another embodiment of the invention in the form of a cooling system
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`with a divided evaporator.
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`Figure 3 shows a more detailed view of the top of the cooling system show at figure 2.
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`Detailed Description of the Invention
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`Figure 1 shows a cooling system 2 which system comprises a compressor 4, which
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`compressor has a pressure outlet connected to a tube 6, which tube 6 is connected to a
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`condenser unit 8 which can be cooled by means of a blowing unit 10 and from which
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`condensing unit a tube 12 leads high pressure refrigerant fiirther to a coil 14. From the
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`coil 14 where further condensing takes place, the refrigerant is flowing flirther into a
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`receiver 16. Here from the refrigerant flows through a tube 18 towards a capillary tube
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`20 and further into an evaporator 22. The low pressure refrigerant from the evapora-
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`tor is flowing back through a tube 24 to the inlet of the compressor 4.
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`Using the new mixture of refrigerants, it is possible by the cooling system 2 shown at
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`figure 1 to achieve very low temperatures even by a single state cooling system. The
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`different refrigerants will evaporate at different temperatures. By mixing refrigerants
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`with sufficient low boiling points with normal boiling points, it is possible to adjust the
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`mixture of refrigerants more or less to a specific temperature. In this way, a highly ef—
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`fective cooling system for low temperature purposes can be achieved. This can lead to
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`a very effective reduction in power consumption by reaching a temperature below -60
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`CC.
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`Figure 2 shows a cooling system for an ultra low temperature freezer. The cooling sys—
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`tem 102 comprises a compressor 104 which compressor 104 has an outlet tube 106
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`that is connected through a condenser 108. The condenser is cooled by blowing means
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`110 and from the condenser 108 a tube 112 lead to a coil 114. From the coil, the re-
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`frigerant is further flowing into a receiver 116. From the receiver 116 is a tube 118
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`leading to a block 125 which comprises a heat exchanger. The gas from the tube 118 is
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`leaving the heat exchanger through a tube 120 which is connected to a capillary tube
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`(not shown). From the capillary tube, a tube 122 leads to the first evaporator 122. A
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`tube 130 leads to the next evaporator 132 from which a tube 134 leads to an evapora-
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`tor 136. From here a tube 138 lead to a further evaporator 140. From here a tube 142
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`leads to the final evaporator 144. From this final evaporator 144, a return tube 146
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`leads to the heat exchanger 125 from which the heat exchanger 125, the return line
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`continues in the tube 124 towards the suction inlet at the compressor 104.
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`Using the new mixture of refrigerant in a cooling system as show at figure 2, it is pos-
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`sible to achieve temperatures as low as -80°C to -90°C in an ultra low temperature
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`freezer that can be achieved by a single compressor with very low energy consumption.
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`The low power consumption leads to low heat dissipation. In order to achieve a low
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`energy consumption, it is necessary to produce an ultra low temperature freezer with
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`sufficient isolation.
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`Figure 3 shows an enlarged view of the upper part of figure 2. Figure 3 shows a cool—
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`ing system 202 comprises a compressor 204 which compressor 204 has an outlet 206
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`connected through a condenser 208 which is cooled by blowing means 210. A tube 212
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`lead to a coil 214 for further condensation from where the refrigerant is sent to a re-
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`ceiver 216. From the receiver, a tube 218 leads to a heat exchanger block 225 where
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`the refrigerant leaves the heat exchanger block 225 through a tube 219 that leads to a
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`flow restriction formed as a capillary tube 220 from which capillary tube the refiigerant
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`flows through a tube 222 towards an evaporator 223. The refrigerant leaves the evapo-
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`rator 223 through a tube 230 to further evaporators (not shown). The refrigerant re-
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`turns from the evaporators through a tube 246 which is sent to the heat exchanger 225.
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`The refiigerant leaves the heat exchanger block 225 through a tube 224 that leads to
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`the inlet of the compressor 204.
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`Using so-called green refrigerants in a system as shown at figure 3, it is possible to
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`achieve an ultra low temperature freezer with refrigerant that are environmentally
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`fiiendly. But also because the cooling system is highly effective, it is possible with a
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`relative low power consumption to achieve very low temperatures.
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`One possible mixtures of refiigerant
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`a: R600 40—60%
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`b:R600a 5—15%
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`c2R115015 —35 %
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`(1: R50
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`1—10%
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`CLAIMS
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`1. A cooling system comprising at least one compressor, at least one condenser, at
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`least a first heat exchanger, at least one flow restriction and at least one evaporator,
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`which cooling system comprises a first non-azeotropic mixture of refrigerants, which
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`non-azeotropic mixture comprises at least the following main components:
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`a: R600, Butane
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`b: R600a, Isobutane
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`e: R1150, Etylcnc,
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`which main components belongs to a group of environmentally friendly refrigerants,
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`characterized in that the non-azeotropic mixture of refrigerants further comprise a
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`least one fill‘thGl‘ refrigerant d: which refrigerant d: has a nature boiling point below —
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`75°C.
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`2. A cooling system according to claim 1, characterized in that the refrigerant d: is part
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`of a mixture of second minor group of refrigerants, in which minor group of refriger-
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`ants belongs to the group of environmentally friendly refrigerants, to which minor
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`group belongs at least one refrigerant has a nature boiling point below - 100°C.
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`3. A cooling system according to claim 1 or 2, characterized in that the second minor
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`group of refrigerants comprises at least one fiirther refrigerant d: which refrigerant d:
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`has a natural boiling point below — 1400C.
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`4. A cooling system according to claim 1 or 2, characterized in that the refrigeration
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`system comprises at least one compressor, which compressor has a pressure outlet
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`connected to a condenser, from which condenser the high pressure refrigerant flows
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`through a heat exchanger,
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`in which heat exchanger the high pressure refrigerant is
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`cooled by low pressure cold refrigerant flowing back towards the suction inlet at the
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`compressor, from which heat exchanger the high pressure refrigerant flows towards a
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`flow restriction in form of a capillary tube, from which capillary tube the low pressure
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`refrigerant flows through an evaporator, from which evaporator the low pressure re—
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`frigerant flows through the heat exchanger back to the suction inlet of the compressor.
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`5. A cooling system according to claim 3, characterized in that the condenser is coil
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`formed.
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`6. A cooling system according to claim 3, characterized in that the evaporator is
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`formed in a number of parallel section for shelves in a cooling shrank.
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`7. A non-azeotropic refrigerant mixture of environmentally friendly refrigerants com-
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`prises a first main group of refrigerants, which first main group comprises at least a
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`mixture of the following refrigerants
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`a: R600, Butane
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`b: R600a, Isobutane
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`c: R1150, Etylene,
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`characterized in that
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`the non-azeotropic refrigerant mixture of environmentally
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`friendly refrigerants comprises at least one refrigerant, which refrigerant belongs to
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`the group of environmentally friendly refrigerants, to which refrigerant d: has a nature
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`boiling point below — 75°C.
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`8. A refrigerant mixture according to claim 6, characterized in that the mixture of
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`refrigerants forms a second minor group of refrigerants which second minor group
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`comprises at least one further refrigerant d: which refrigerant d. has a natural boiling
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`point below — 140°C.
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`9. A refrigerant mixture according to claim 6 or 7, characterized in that the main
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`group of refrigerants (a, b, c) comprises more than 60% of the weight of the refrigerant
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`mixture, which minor group of ref