CN114526561A - Low GWP cascade refrigeration system - Google Patents
Low GWP cascade refrigeration system Download PDFInfo
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- CN114526561A CN114526561A CN202111609565.6A CN202111609565A CN114526561A CN 114526561 A CN114526561 A CN 114526561A CN 202111609565 A CN202111609565 A CN 202111609565A CN 114526561 A CN114526561 A CN 114526561A
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- 238000005057 refrigeration Methods 0.000 title claims abstract description 47
- 239000013529 heat transfer fluid Substances 0.000 claims abstract description 25
- 238000001816 cooling Methods 0.000 claims abstract description 11
- 239000003507 refrigerant Substances 0.000 claims description 175
- 239000000203 mixture Substances 0.000 claims description 50
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 49
- CDOOAUSHHFGWSA-OWOJBTEDSA-N (e)-1,3,3,3-tetrafluoroprop-1-ene Chemical compound F\C=C\C(F)(F)F CDOOAUSHHFGWSA-OWOJBTEDSA-N 0.000 claims description 37
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 27
- 239000012530 fluid Substances 0.000 claims description 23
- FXRLMCRCYDHQFW-UHFFFAOYSA-N 2,3,3,3-tetrafluoropropene Chemical compound FC(=C)C(F)(F)F FXRLMCRCYDHQFW-UHFFFAOYSA-N 0.000 claims description 17
- 238000001704 evaporation Methods 0.000 claims description 11
- 239000000314 lubricant Substances 0.000 claims description 11
- 230000006835 compression Effects 0.000 claims description 10
- 238000007906 compression Methods 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 10
- 238000004891 communication Methods 0.000 claims description 9
- 150000004996 alkyl benzenes Chemical class 0.000 claims description 4
- 229920001515 polyalkylene glycol Polymers 0.000 claims description 4
- 229920013639 polyalphaolefin Polymers 0.000 claims description 4
- -1 polyol esters Chemical class 0.000 claims description 4
- FDMFUZHCIRHGRG-UHFFFAOYSA-N 3,3,3-trifluoroprop-1-ene Chemical compound FC(F)(F)C=C FDMFUZHCIRHGRG-UHFFFAOYSA-N 0.000 claims description 3
- 239000001569 carbon dioxide Substances 0.000 claims description 2
- 239000002480 mineral oil Substances 0.000 claims description 2
- 229920005862 polyol Polymers 0.000 claims description 2
- 229920002545 silicone oil Polymers 0.000 claims description 2
- 241001465754 Metazoa Species 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 15
- 239000003570 air Substances 0.000 description 11
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical group CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 8
- 238000004378 air conditioning Methods 0.000 description 7
- 230000008020 evaporation Effects 0.000 description 7
- 239000007788 liquid Substances 0.000 description 7
- YFMFNYKEUDLDTL-UHFFFAOYSA-N 1,1,1,2,3,3,3-heptafluoropropane Chemical compound FC(F)(F)C(F)C(F)(F)F YFMFNYKEUDLDTL-UHFFFAOYSA-N 0.000 description 6
- 230000005494 condensation Effects 0.000 description 4
- 238000009833 condensation Methods 0.000 description 4
- 239000001294 propane Substances 0.000 description 4
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical group CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 231100000419 toxicity Toxicity 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- 238000010792 warming Methods 0.000 description 2
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/10—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point with several cooling stages
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B40/00—Subcoolers, desuperheaters or superheaters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/006—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant containing more than one component
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
- C09K5/02—Materials undergoing a change of physical state when used
- C09K5/04—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa
- C09K5/041—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems
- C09K5/044—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems comprising halogenated compounds
- C09K5/045—Materials undergoing a change of physical state when used the change of state being from liquid to vapour or vice versa for compression-type refrigeration systems comprising halogenated compounds containing only fluorine as halogen
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B7/00—Compression machines, plants or systems, with cascade operation, i.e. with two or more circuits, the heat from the condenser of one circuit being absorbed by the evaporator of the next circuit
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/002—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant
- F25B9/008—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the refrigerant the refrigerant being carbon dioxide
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
- F25B2400/12—Inflammable refrigerants
- F25B2400/121—Inflammable refrigerants using R1234
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Combustion & Propulsion (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Lubricants (AREA)
Abstract
The present application relates to low GWP cascaded refrigeration systems. Disclosed is a cascade refrigeration system for providing cooling of air located in an enclosure occupied by or to be exposed to humans or other animals during normal use, wherein the system comprises: (1) a first relatively low temperature heat transfer loop having a first evaporator located within the enclosure and a first heat transfer fluid in the low temperature heat transfer loop; (2) a second heat transfer loop substantially outside the enclosure containing a second heat transfer fluid; (3) a heat exchanger acting as a condenser in the low temperature loop, thermally coupled to the high temperature loop by rejecting heat into a second heat transfer fluid; and (4) a heat exchanger in the high temperature loop that transfers heat from the second heat transfer fluid exiting the high temperature condenser to the portion of the second heat transfer fluid that is passed to the suction side of the compressor.
Description
Cross reference to related applications
The application is a divisional application of an invention patent application with application date of 2017, 3, 24 and application number of 201780019272.8 and named as a low GWP cascade refrigeration system. This application claims priority to provisional application 62/313,177 filed on 25/3/2016, which is hereby incorporated by reference in its entirety.
This application is also a continuation of and claims priority to U.S. application No. 15/468,292 filed 24.3.2017, which is hereby incorporated by reference in its entirety.
This application is also a continuation-in-part application of U.S. application No. 15/400,891 filed on 6.1.2017, which is currently pending, which in turn claims priority to provisional application 62/275,382 filed on 6.1.2016, each of which is incorporated herein by reference in its entirety.
This application is also a continuation-in-part application of U.S. application No. 15/434,400 filed on 16.2.2017, which is currently pending, which in turn claims the benefit of priority to 62/295,731 filed on 16.2.2016, each of which is incorporated herein by reference in its entirety.
Technical Field
The present invention relates to efficient, low global warming potential ("low GWP") air conditioning and/or refrigeration systems and methods of providing cooling that are safe and effective.
Background
In typical air conditioning and refrigeration systems, a compressor is used to compress a heat transfer vapor from a lower pressure to a higher pressure, which in turn adds heat to the vapor. This added heat is typically rejected in a heat exchanger often referred to as a condenser. The heat transfer vapor entering the condenser is condensed to produce a liquid heat transfer fluid at a relatively high pressure. Typically the condenser uses a large amount of fluid available in the ambient environment, such as ambient outside air, as a heat sink. Once it has condensed, the high pressure heat transfer fluid undergoes a substantially isenthalpic expansion, which will occur by passing the fluid through an expansion device or valve where it is expanded to a lower pressure, which in turn causes a temperature drop to occur in the fluid. The lower pressure, lower temperature heat transfer fluid from the expansion operation is then typically sent to an evaporator where it absorbs heat and is thereby vaporized. This evaporation process in turn leads to cooling of the fluid or body (body) intended to be cooled. In many typical air conditioning and refrigeration applications, the fluid being cooled is air contained in the area to be cooled, such as air in a residential open air conditioner or air inside a walk-in refrigerator (walk-in cooler) or supermarket refrigerator or freezer (supermarket cooler). After the heat transfer fluid has evaporated at low pressure in the evaporator, it is sent back to the compressor, where the cycle begins again.
The complex and interrelated combination of factors and requirements are associated with creating an air conditioning system that is efficient, effective, and safe, and at the same time environmentally friendly, i.e., having both low GWP impact and low ozone depletion ("ODP") impact. For efficiency (effectiveness) and effectiveness (effectiveness), it is important that the heat transfer fluid operate at high levels of efficiency and high relative capacities in air conditioning and refrigeration systems. At the same time, it is important that the heat transfer fluid have both low GWP values and low ODP values, since the fluid is likely to escape to the atmosphere over time.
Applicants have recognized that while certain fluids are capable of achieving both high levels of efficiency and efficacy and simultaneously low levels of both GWP and ODP, many fluids meeting this combination of requirements suffer from drawbacks having safety-related drawbacks. For example, fluids that might otherwise be acceptable may be undesirable due to flammability properties and/or toxicity issues. The applicant has realised that the use of fluids of such nature is particularly undesirable in typical air conditioning and in many refrigeration systems, as such flammable and/or toxic fluids may be inadvertently released into cooled homes, walk-in refrigerators, cold-boxes, chillers (killers), freezers or transport refrigeration boxes (transport refrigeration boxes), thus exposing or potentially exposing occupants thereof to hazardous conditions. The applicant has also realised that for relatively small systems, for example systems with a capacity of less than 30kw, the problem is of even greater concern, as for such systems the cost of effective safety protection systems, such as fire protection systems, is generally not economically viable.
Disclosure of Invention
According to one aspect of the present invention there is provided a cascade refrigeration system for providing direct or indirect cooling, but preferably direct cooling, of air located in an enclosure (enclosure) that is occupied by or will be exposed to humans or other animals during normal use. As used herein, the term "enclosure" refers to a space that is at least partially enclosed (e.g., the enclosure may be open on one or more sides, or closed) and includes air that has been cooled.
A preferred embodiment of the present system includes at least a first evaporator located within the enclosure and being part of a first relatively low temperature heat transfer loop (circuit). The low temperature heat transfer loop preferably comprises a first heat transfer fluid in a vapor compression cycle loop (loop) comprising at least: a compressor for increasing the pressure of the first heat transfer composition; a heat exchanger for condensing at least a portion of the first heat transfer composition from the compressor at a relatively high pressure; an expansion device for reducing the pressure of the heat transfer composition from the condenser; and an evaporator for absorbing heat from the enclosure to be cooled into the heat transfer composition. Preferably one or more, most preferably all, of said compressor, condenser and expansion valve are located outside the housing and said evaporator is located inside the housing.
The system of the present invention also preferably includes a second heat transfer loop located substantially outside the enclosure, which is sometimes referred to herein for convenience as a "high temperature" loop. The high temperature loop preferably comprises a second heat transfer fluid in a vapor compression cycle loop, the loop comprising at least a compressor, a heat exchanger for condensing the heat transfer fluid in the high temperature loop, preferably by heat exchange with ambient air outside the enclosure, and an expansion device for reducing the pressure of the second heat transfer fluid from the compressor.
An important aspect of preferred embodiments of the present invention is that the heat exchanger, which acts as a condenser in the low temperature loop, is thermally coupled to the high temperature loop by rejecting heat to the second heat transfer fluid, preferably by evaporating at least a significant portion of said second heat transfer fluid. In this manner, the condenser of the low temperature loop and the evaporator of the high temperature loop are thermally coupled in the heat exchanger, which is sometimes referred to as a "cascade heat exchanger" in the systems and methods of the present invention for convenience.
Another important aspect of the present invention, which in preferred embodiments comprises the presence of a heat exchanger in the high temperature loop, has been found to advantageously and unexpectedly improve system performance by transferring heat from the second heat transfer fluid exiting the high temperature condenser to the portion of the second heat transfer fluid that is passed to the suction side of the compressor. This heat exchanger is sometimes referred to herein for convenience as a "suction line heat exchanger".
Another important aspect of the preferred system is that the first heat transfer fluid circulating in the cryogenic circuit comprises a refrigerant having a GWP of no greater than about 500, more preferably no greater than about 400, and even more preferably no greater than about 150, and further that the first heat transfer fluid is significantly less flammable than the second heat transfer fluid. Preferably, the second heat transfer fluid circulating in the high temperature loop also contains a refrigerant having a GWP of no greater than about 500, more preferably no greater than about 400, still more preferably no greater than about 150, but since the heat transfer fluid will never enter the enclosure in normal operation, applicants have found it advantageous to use a fluid in the high temperature loop that has one or more properties, such as flammability, toxicity, etc., that would be considered disadvantageous if it were circulating within the enclosure. In this way, as explained in detail below, the present system enables additional possible surprising advantages to be achieved over systems that would rely on only the first heat transfer composition or only the second heat transfer composition.
In certain preferred embodiments, the second refrigerant comprises, more preferably comprises at least about 50% by weight, even more preferably at least about 75% by weight, trans-1, 3,3, 3-trifluoropropene (HFO-1234ze (E)) and/or HFO-1234yf, and the flammability of the second refrigerant is greater than, preferably significantly greater than, the flammability of CO 2. In another embodiment, the second refrigerant comprises, more preferably comprises at least about 75% by weight, even more preferably at least about 80% by weight, trans-1, 3,3, 3-trifluoropropene (HFO-1234ze (E)) and/or HFO-1234 yf.
Drawings
FIG. 1 is a generalized process flow diagram of a preferred embodiment of an air conditioning system according to the present invention; and
fig. 2 is a typical walk-in chiller refrigeration system on which comparative example C1 is based.
Detailed Description
Preferred heat transfer compositions
In preferred embodiments described herein, the system comprises:
(a) a relatively low temperature vapor compression circuit comprising a compressor, an expander and an evaporator in fluid communication in said circuit, and a first heat transfer composition comprising a first refrigerant and preferably a compressor lubricant in said circuit, said evaporator being located in a housing containing air to be cooled and capable of absorbing heat from said air at about said relatively low temperature;
(b) a relatively high temperature vapor compression circuit comprising a compressor, a condenser, an expander and a suction line heat exchanger in fluid communication in said circuit, and a second heat transfer composition comprising a second refrigerant and preferably a compressor lubricant in said circuit, said condenser being capable of transferring heat to a heat sink located outside said shell; and
(c) a cascade heat exchanger for condensing the first refrigerant and evaporating the second refrigerant by heat exchange between the first and second refrigerants,
wherein the suction line heat exchanger is in fluid communication with the cascade heat exchanger to receive at least a portion of the second heat transfer composition exiting the cascade heat exchanger and increase its temperature by absorbing heat from the second heat transfer composition exiting the condenser and thereby reduce the temperature of the second heat transfer composition before it enters the relatively high temperature vapor compression loop expander.
As used herein, the terms "relatively low temperature" and "relatively high temperature," when used in relation to the first and second heat transfer circuits together, and unless otherwise indicated, are used in a relative sense to indicate the relative temperatures of the indicated heat transfer compositions, wherein they differ by at least about 5 ℃.
Preferably, the flammability of the first refrigerant is significantly less than the flammability of the second refrigerant. In a preferred embodiment, the first refrigerant has a flammability according to ASHRAE Standard 34 (which is specified to be measured according to ASTM E681) classified as a1, and the second refrigerant has a flammability according to ASHRAE Standard 34 classified as A2L or a flammability higher than A2L, although A2L classification is preferred for the second refrigerant. It is also preferred that the first and second refrigerants each have a Global Warming Potential (GWP) of less than about 150.
In a preferred embodiment, the first refrigerant circulating in the low temperature loop comprises, preferably consists essentially of, more preferably in some embodiments consists of carbon dioxide.
Preferably the second refrigerant comprises one or more of: trans-1, 3,3, 3-tetrafluoropropene (HFO-1234ze (E)), 2,3,3, 3-tetrafluoropropene (HFO-1234yf), R-227ea, and R-32, and combinations of two or more of these. In preferred embodiments, the second refrigerant comprises at least about 50 weight percent, more preferably at least about 80 weight percent, of 2,3,3, 3-tetrafluoropropene (HFO-1234 yf). In other preferred embodiments, the second refrigerant comprises at least about 50 wt.%, more preferably at least about 80 wt.% or at least about 75 wt.%, more preferably at least about 80 wt.% trans 1,3,3, 3-tetrafluoropropene (HFO-1234ze (e)). In highly preferred embodiments, the second refrigerant comprises at least about 95% by weight of HFO-1234ze (E), HFO-1234yf, or a combination of two or more of these, and in some embodiments consists essentially of, or consists of HFO-1234ze (E), HFO-1234yf, or a combination of two or more of these.
In other highly preferred embodiments, the second refrigerant comprises from about 70% to about 90% by weight of HFO-1234yf, preferably from about 80% by weight of HFO-1234yf, and from about 10% to about 30% by weight of R32, preferably about 20% by weight of R-32.
In other highly preferred embodiments, the second refrigerant comprises from about 70% to about 90% by weight HFO-1234ze (E), preferably from about 80% by weight HFO-1234ze (E), and from about 10% to about 30% by weight R32, preferably about 20% by weight R-32.
In other highly preferred embodiments, the second refrigerant comprises from about 85% to about 90% by weight trans 1,3,3, 3-tetrafluoropropene (HFO-1234ze (e)) and from about 10% to about 15% by weight 1,1,1,2,3,3, 3-heptafluoropropane (HFC-227ea), and even more preferably in some embodiments comprises from about 88% trans 1,3,3, 3-tetrafluoropropene (HFO-1234ze (e)) and about 12% by weight 1,1,1,2,3,3, 3-heptafluoropropane (HFC-227 ea).
Those skilled in the art will recognize from the disclosure contained herein that preferred embodiments of the present invention provide the advantage of utilizing only safe (relatively low toxicity and low flammability) low GWP refrigerants within the enclosure to be cooled and relatively less safe but preferably low GWP refrigerants in high temperature circuits located entirely outside the enclosure.
As used herein, the terms "safe" and "relatively less safe," when used in relation to the first and second heat transfer circuits together, and unless otherwise indicated, are used in a relative sense to indicate the relative safety of the heat transfer compositions shown. Such a configuration, particularly when the high temperature system includes the preferred suction line heat exchanger, makes the system and method of the present invention highly preferred for use in close proximity to the site of a human or other animal occupying or using the enclosure, as is commonly encountered in walk-in freezers, supermarket refrigerators and the like.
Preferred embodiments of the second refrigerant are disclosed in the following table:
the first heat transfer composition and the second heat transfer composition typically also each include a lubricant, typically in an amount of from about 30 to about 50 weight percent of the heat transfer composition, with the balance comprising the refrigerant and other optional components that may be present. Combinations of surfactants and solubilizers may also be added to the present compositions to aid in oil solubility as disclosed in U.S. Pat. No.6,516,837, the disclosure of which is incorporated herein by reference. Conventional refrigeration lubricants used with Hydrofluorocarbon (HFC) refrigerants in refrigeration machinery, such as polyol esters (POE) and polyalkylene glycols (PAG), silicone oils, mineral oils, Alkylbenzenes (AB) and poly (alpha-olefins) (PAO), may be used with the refrigerant compositions of the present invention. Preferably, the lubricant is POE.
The following provides preferred combinations of the first refrigerant, the second refrigerant and the lubricant according to an aspect of the present invention.
System operating conditions
It is generally recognized that the operating conditions used in the present systems and methods can vary widely depending on the particular application based on the disclosure contained herein. However, many preferred applications will advantageously use operating parameters within the ranges indicated in the following table, all amounts being understood as modified by "about":
| width of | Medium and high grade | Narrow and narrow | |
| Evaporation temperature of the Low grade evaporator,. degree.C | -45 to-25 | -40 to-30 | -35 |
| Low condensing temperature, deg.C | -10 to 10 | -5 to 5 | 0 |
| High evaporation temperature of higher order, DEG C | -15 to 5 | -10 to 0 | -5 |
| High condensation temperature, DEG C | 35 to 55 | 40 to 50 | 45C |
| Evaporator superheat (at various stages), deg.C | 0 to 15 | 0 to 10 | 5 |
| Temperature rise in the lower suction line, DEG C | 5 to 25 | 10 to 20 | 15 |
| Temperature rise in the advanced suction line, DEG C | 0 to 15 | 0 to 10 | 5 |
| Super cooling (sub cooling) of expansion device for both high and low stages, DEG C | 0 to 10 | 0 to 5 | 0 |
| Compressor discharge temperature (low and high), deg.C | About 120 to about 130 | About 125 to about 130 | Not greater than 125 |
When operating within process conditions according to the invention, the use of a suction line heat exchanger as described herein preferably results in at least a 2% COP improvement, more preferably at least about a 3% COP improvement, even more preferably a 4% COP improvement, compared to the same system without a suction line heat exchanger according to the invention.
In the following description, components or elements of a system that are or may be generally the same or similar in different embodiments are identified with the same numerals or symbols.
A preferred refrigeration system is illustrated in figure 1. The refrigeration system is generally designated 10. The boundary, generally designated 100, schematically represents the housing. The low temperature loop comprises a compressor 11, a condenser side 12A of a cascade exchanger 12, an expansion valve 14 and an evaporator 15. As shown, evaporator 15 is located within enclosure 100 along with any associated conduits and other connections and associated equipment to transport the first heat transfer composition to and from the enclosure boundaries. Although evaporator 14 is preferably located within the housing and is disclosed in the illustrated figures as being located within housing 100, it is to be understood that in certain embodiments, it may be desirable and/or necessary to provide expander 14 outside of the housing. The high temperature loop, comprising compressor 21, evaporator side 12B of cascade exchanger 12, expansion valve 24 and condenser 25, is located outside enclosure 100 along with any associated conduits and other connections and associated equipment. The high temperature loop also includes a suction line heat exchanger 50 that enables heat to be exchanged between a second heat transfer composition stream 30 exiting the condenser 25 and a second heat transfer composition stream 31 exiting the evaporation side 12B of the cascade heat exchanger 12.
While it is contemplated that the relative sizes of the first and second refrigeration circuits according to the present invention may vary widely within the scope hereof, applicants have found that highly advantageous results may be achieved in certain embodiments by careful selection of the relative sizes of the refrigeration circuits. More specifically, it is expected and understood that under normal operating conditions, the heat transfer compositions contained in the first refrigeration circuit and the second refrigeration circuit will never mix or blend. However, the applicant has realised that such a possibility of intermixing of the first and second refrigerants may occur, for example, in the event of a leak in the cascade heat exchanger. In the event of a leak within the cooled enclosure, this mixed refrigerant stream may then become exposed to humans or other animals located within or near the enclosure. Thus, to ensure continued safe operation even in the event of such a leak, the applicant has realised that careful and careful selection of the relative refrigeration circuit dimensions can result in a system that is safe even in the event of such a leak.
While applicants contemplate that the systems and compositions of the present invention will find use in a number of refrigeration applications, preferred applications include refrigeration systems and methods for use, for example, in applications for treating air (including cooling and/or heating) in enclosures such as residential homes, office spaces, warehouses, and the like, as well as in association with enclosures such as walk-in refrigerators, freezers, transport freezers, and the like, for keeping items cold by cooling the air in the enclosure. As used herein, the term "transport refrigeration box" is used to refer to a refrigerated/insulated box located on or forming a part of or substantially all of a truck trailer. Furthermore, in a preferred application, the capacity (capacity) of the system according to the invention is less than about 30 kW. In a preferred application, the capacity of the system according to the invention is less than about 15kW, and in still other applications the capacity of the system according to the invention is less than about 10 kW.
Several examples of preferred systems, methods, and compositions are described below:
A. the first refrigerant is CO2 and the second refrigerant is R-1234ze (E)
By way of example, applicants have considered a cascade refrigeration system according to the present invention wherein the first refrigerant consists of CO2 and the second refrigerant consists of R01234ze (E). In order to obtain a refrigeration system according to the invention that is safe even in the event of intermixing between the first and second refrigerants, the applicant has determined that the flammability of various mixtures (including vapour and liquid) of these components is as follows:
based on the above considerations and analysis and preferred aspects of the present invention wherein the first refrigerant consists essentially of CO2 and the second refrigerant consists essentially of R-1234ze (E), it is preferred that the charge weight ratio of the first refrigerant (e.g., CO2) to the second refrigerant (e.g., R-1234ze (E)) in the cryogenic circuit is not less than about 1.2. In such embodiments, the system of the present invention will remain safe even with complete intermixing between the first and second refrigerant compositions, i.e., containing only non-flammable refrigerants.
B. The first refrigerant is CO2 and the second refrigerant is SR26
As a further example, applicants have contemplated a cascade refrigeration system according to the present invention wherein the first refrigerant consists of CO2 and the second refrigerant consists of SR26(R-1234ze (E): 80:20 weight ratio combination of R-32). In order to obtain a refrigeration system according to the invention that is safe even in the event of intermixing between the first and second refrigerants, the applicant has determined that the flammability of various mixtures (including vapour and liquid) of these components is as follows:
based on the above considerations and analysis and preferred aspects of the present invention wherein the first refrigerant consists essentially of CO2 and the second refrigerant consists essentially of SR26, it is preferred that the charge weight ratio of the first refrigerant (e.g., CO2) to the second refrigerant (e.g., SR26) in the low temperature loop is not less than about 1.0. In such embodiments, the system of the present invention will remain safe even with complete intermixing between the first and second refrigerant compositions, i.e., containing only non-flammable refrigerants.
C. The first refrigerant is CO2 and the second refrigerant is R-32
As an additional example, applicants have considered a cascade refrigeration system according to the present invention wherein the first refrigerant consists of CO2 and the second refrigerant consists of R-32. In order to obtain a refrigeration system according to the invention that is safe even in the event of intermixing between the first and second refrigerants, the applicant has determined that the flammability of various mixtures (including vapour and liquid) of these components is as follows:
based on the above considerations and analysis and preferred aspects of the present invention wherein the first refrigerant consists essentially of CO2 and the second refrigerant consists essentially of SR26, it is preferred that the charge weight ratio of the first refrigerant (e.g., CO2) to the second refrigerant (e.g., SR26) in the low temperature loop is not less than about 0.9. In such embodiments, the system of the present invention will remain safe even with complete intermixing between the first and second refrigerant compositions, i.e., containing only non-flammable refrigerants.
D. The first refrigerant is CO2 and the second refrigerant is ethane
As an additional example, applicants have considered a cascade refrigeration system according to the present invention wherein the first refrigerant consists of CO2 and the second refrigerant consists of ethane. In order to obtain a refrigeration system according to the invention that is safe even in the event of intermixing between the first and second refrigerants, the applicant has determined that the flammability of various mixtures (including vapour and liquid) of these components is as follows:
based on the above considerations and analysis and preferred aspects of the present invention wherein the first refrigerant consists essentially of CO2 and the second refrigerant consists essentially of ethane, it is preferred that the charge weight ratio of the first refrigerant (e.g., CO2) to the second refrigerant (e.g., SR26) in the cryogenic circuit is not less than about 1.7. In such embodiments, the system of the present invention will remain safe even with complete intermixing between the first and second refrigerant compositions, i.e., containing only non-flammable refrigerants.
E. The first refrigerant is CO2 and the second refrigerant is propane
As an additional example, applicants have considered a cascade refrigeration system according to the present invention wherein the first refrigerant consists of CO2 and the second refrigerant consists of propane. In order to obtain a refrigeration system according to the invention that is safe even in the event of intermixing between the first and second refrigerants, the applicant has determined that the flammability of various mixtures (including vapour and liquid) of these components is as follows:
based on the above considerations and analysis and the preferred aspect of the present invention wherein the first refrigerant consists essentially of CO2 and the second refrigerant consists essentially of propane, it is preferred that the charge weight ratio of the first refrigerant (e.g., CO2) to the second refrigerant (e.g., propane) in the cryogenic circuit is greater than 4. In such embodiments, the system of the present invention will remain safe even with complete intermixing between the first and second refrigerant compositions, i.e., containing only non-flammable refrigerants.
Examples
Comparative example C1
Comparative example C1, described below, is based on a typical walk-in refrigerator refrigeration system as illustrated in fig. 2.
In fig. 2, the boundaries of the refrigerated compartment are schematically represented by block 100. Enclosed within the refrigerated compartment box is an evaporator 15 and an expander 14. The compressor 11 and the condenser 20 are located outside the refrigerating compartment block 100. The refrigerant circulating in this refrigeration circuit is refrigerant R-404A (52 wt% R-143a, 44 wt% R-125 and 4 wt% R-134A).
The following operating parameters were used:
the evaporation temperature of the evaporator 15 = -35 deg.c
Condensation temperature = 45 ℃ of condenser 200
Isentropic efficiency of expander 14 = 63%
Evaporator superheat = 5 ℃
Temperature rise in the compressor suction line = 20 ℃
Expansion device subcooling = 0 deg.c
Operation of this typical system produces a compressor discharge temperature of 108.3 ℃.
Hybrid examples H1A-H1D
A hybrid system based on a typical refrigeration system as shown in example 1 was formed, but a suction line heat exchanger was inserted to absorb heat into the R-404A leaving the evaporator and thereby increase the temperature of the R-404A entering the compressor by absorbing heat from the R-404A leaving the condenser before the stream entered the expander. The operation was evaluated using a suction line heat exchanger with efficiency values (efficiency values) varying from 35% to 85%. The results are reported in the following table H1, together with the results of comparative example C1 for comparison:
TABLE H1
| C1 | H1A | H1B | H1C | H1D | |
| Potency%) | 0 (without heat exchanger) | 35 | 55 | 75 | 85 |
| Compressor discharge temperature,. deg.C | 108.3 | 133.1 | 150.0 | 166.5 | 174.7 |
As used herein,% effectiveness of a suction line heat exchanger refers to the percentage of ideal operation without heat loss.
As can be seen from the results reported above, it is not feasible to modify a typical system to include a suction line heat exchanger, since in each case a significant and undesirable increase in compressor discharge temperature occurs as a result of operating such a hybrid system.
Examples 1A-1E, 2A-2E, 3A-3E, 4A-4E and 5A-5E
Operating a cascade refrigeration system having a suction line heat exchanger as shown in fig. 1 in a cryogenic circuit using HFO-1234ze (e); HFO-1234 yf; SR21(80 wt.% HFO-1234yf and 20 wt.% R-32); SR26 (80% by weight HFO-1234ze (E) and 20% by weight R-32); and SR31(88 wt.% HFO-1234ze (E) and 12 wt.% R-32). The refrigerant in the high temperature circuit being CO2. Using these refrigerants, the cascade system of the present invention operates according to the following parameters:
the evaporation temperature of the lower grade (evaporator 15) = -35 deg.C
Condensation temperature of low grade = (cascade condenser 12A) = 0 ° c
The evaporation temperature of the higher grade (evaporator 25) = -5 deg.C
Condensation temperature = 45 ℃ of the higher stage (cascade condenser 12B)
Isentropic efficiency of the low stage expander (expander 14) = 65%
Isentropic efficiency of the high stage expander (expander 24) = 63%
Evaporator superheat (two evaporators) = 5 deg.c
Temperature rise in the low grade suction line = 15 ℃
Temperature rise in the superior suction line = 5 deg.c
Subcooling of the expansion device for both the high and low stages = 0 deg.c
Suction line liquid line heat exchanger effectiveness = varied from 0% to 85%.
The following table 1/5-DT shows the results for the discharge temperatures of the examples, showing the results from comparative example 1 for comparison:
as revealed by the above table, all embodiments of the present invention meet the preferred compressor discharge temperature of the present invention and in all cases the discharge temperature is significantly better than the performance of the typical system and even hybrid systems.
The following table 1/5-COP shows the results of the COPs of the examples, showing the results from comparative example 1 for comparison:
as disclosed in the above table, all examples of the invention produced at least 121% improved COP compared to the system of comparative example 1. Furthermore, all inventive systems including a suction line heat exchanger show at least an additional 2% improvement over the inventive system without a heat exchanger, and systems with a suction line heat exchanger having a heat exchanger efficiency of 55% or more show at least an additional 3% improvement over the system without a heat exchanger.
Examples 6A to 6E, 7A to 7E, 8A to 8E, 9A to 9E
The following respective refrigerants (second refrigerant) are used in the low-temperature circuit and CO is used in the high-temperature circuit2(showing GWP of each refrigerant) a cascade refrigeration system without a suction line heat exchanger and with a suction line heat exchanger as shown in figure 1 was operated:
the system of figure 1 was operated with each of the refrigerants EX6-EX9 using the same operating conditions specified in examples 1-5, and the following tables 6/9-DT show the results for the discharge temperatures of each example, showing the results from comparative example 1 for comparison:
as the above table reveals, the use of refrigerant EX6-EX9 produces acceptable discharge temperatures (within the preferred discharge temperature range) for a cascade system without a suction line heat exchanger (efficiency = 0). However, none of the refrigerants produce an acceptable discharge temperature (within the preferred discharge temperature range) for a cascade system of any efficacy value of 35% to 85%.
Examples 10A to 10E, 11A to 11E, 12A to 12E, 13A to 13E, 14A to 14E, 15A to 15E
A cascade refrigeration system without a suction line heat exchanger and with a suction line heat exchanger as shown in fig. 1 was operated using the following refrigerants (second refrigerant) in the low temperature loop and CO2 in the high temperature loop:
the system of figure 1 was operated with each of the refrigerants EX10-EX15 using the same operating conditions specified in examples 1-5, and the following tables 10/15-DT show the results for the discharge temperatures of each example, showing the results from comparative example 1 for comparison:
as the above table reveals, the use of refrigerant EX10-EX15 produces a second refrigerant with a GWP value below 500, but not every refrigerant produces an acceptable discharge temperature (i.e., within the preferred discharge temperature range). For a cascade system without a suction line heat exchanger (efficiency = 0), the discharge temperature is acceptable. However, for systems with suction line heat exchangers, each EX10-EX 13 refrigerant produces unacceptable discharge temperatures for the required 85% or higher efficiency values. Only EX 14 and EX15 provided acceptable discharge temperatures for the suction line heat exchanger with any of the efficacy values tested. These findings are summarized below:
o at 35% potency, more than 30% of R1234ze (E) is required
o at 55% potency: more than 50% of R1234ze (E) is required
o at 75% potency: more than 60% of R1234ze (E) is required
o at 85% potency: more than 70% of R1234ze (E) is required
o compositions containing at least about 78% R-1234ze (E) are acceptable for all performance values of the suction line heat exchanger and yield GWP values of about 150 or less.
The following table 11/15-COP shows the results of the COPs of the examples, showing the results from comparative example 1 for comparison:
as disclosed in the above table, all examples of the invention produced at least 121% COP compared to the system of comparative example 1. Furthermore, the use of the refrigerant of example 15 in all of the inventive tested systems including a suction line heat exchanger showed at least an additional 2% improvement over the inventive system without a suction line heat exchanger. The use of the refrigerant of example 14 in a tested system of the present invention comprising a suction line heat exchanger having a performance of at least 55% showed at least an additional 2% improvement over the system of the present invention without a suction line heat exchanger and (as shown in table 11/15-DT) had an acceptable discharge temperature. The use of the refrigerant of example 13 in a tested system of the present invention including a suction line heat exchanger having a capacity of at least 55% but less than about 85% showed at least an additional 2% improvement over the system of the present invention without a suction line heat exchanger and (as shown in table 11/15-DT) had an acceptable discharge temperature.
In contrast, while the use of the refrigerant of example 12 in a tested system of the present invention including a suction line heat exchanger having a performance of at least 75% showed at least an additional 2% improvement over the system of the present invention without a suction line heat exchanger, the refrigerant did not provide an acceptable discharge temperature for such conditions as shown in table 11/15-DT.
Examples 16A to 16E, 17A to 17E, 18A to 18E, 19A to 19E
The following respective refrigerants (second refrigerant) were used in the high-temperature circuit and CO was used in the low-temperature circuit2(showing GWP of each refrigerant) a cascade refrigeration system without a suction line heat exchanger and with a suction line heat exchanger as shown in figure 1 was operated:
the system of figure 1 was operated with each of the refrigerants EX16-EX19 using the same operating conditions specified in examples 1-5, and the following tables 16/19-DT show the results for the discharge temperatures of each example, showing the results from comparative example 1 for comparison:
as the above table reveals, the use of refrigerant EX16-EX19 produces acceptable discharge temperatures (within the preferred discharge temperature range) for a cascade system without a suction line heat exchanger (efficiency = 0). However, none of the refrigerants produce an acceptable discharge temperature (within the preferred discharge temperature range) for a cascade system of any efficacy value of 35% to 85%.
Examples 20A to 20E, 21A to 21E, 22A to 22E, 23A to 23E, 24A to 24E, 25A to 25E
A cascade refrigeration system without a suction line heat exchanger and with a suction line heat exchanger as shown in fig. 1 was operated using the following respective refrigerants (second refrigerant) in the low temperature loop and CO2 in the high temperature loop:
the system of figure 1 was operated with each of the refrigerants EX20-EX25 using the same operating conditions specified in examples 1-5, and the following tables 20/25-DT show the results for the discharge temperatures of each example, showing the results from comparative example 1 for comparison:
as the above table reveals, the use of refrigerant EX 21-EX 25 produces a second refrigerant with a GWP value below 500, but not every refrigerant produces an acceptable discharge temperature (i.e., within the preferred discharge temperature range). For a cascade system without a suction line heat exchanger (efficiency = 0), the discharge temperature is acceptable. However, for systems having suction line heat exchangers, each refrigerant EX20-EX 22 produces an unacceptable discharge temperature for a desired efficiency value of 85% or greater. Only EX 23, EX24 and EX25 provided acceptable discharge temperatures for all tested performance values of the suction line heat exchanger. These findings are summarized below:
o at 35% potency, more than 30% of R1234yf is required
o at 55% potency: more than 40% of R1234yf is required
o at 75% and 85% potency: more than 60% of R1234yf is required.
The following table 20/25-COP shows the results of the COPs of the examples, showing the results from comparative example 1 for comparison:
as disclosed in the above table, all examples of the invention produced at least 121% COP compared to the system of comparative example 1. Furthermore, the use of the refrigerants of examples 24 and 25 in all of the tested systems of the present invention including a suction line heat exchanger showed at least an additional 2% improvement over the system of the present invention without a suction line heat exchanger, and the refrigerants of examples 22 and 23 showed at least an additional 2% improvement over the system of the present invention without a suction line heat exchanger for heat exchangers having an effectiveness of 55% or higher. The use of the refrigerant of example 22 in a tested system of the present invention comprising a suction line heat exchanger having a capacity of at least 75% showed at least an additional 2% improvement over the system of the present invention without a suction line heat exchanger.
Importantly, the use of the refrigerants of examples 24 and 25 in all of the inventive tested systems including a suction line heat exchanger not only showed at least an additional 2% improvement over the inventive system without a suction line heat exchanger, but such refrigerants (as shown in table 21/25-DT) also had acceptable discharge temperatures for all of the suction line heat exchanger performance levels tested. The use of the refrigerants of examples 22 and 23 in tested systems of the present invention comprising a suction line heat exchanger with 55% effectiveness not only showed at least an additional 2% improvement over the inventive system without a suction line heat exchanger, but also (as shown in table 21/25-DT) had acceptable discharge temperatures.
In contrast, while the refrigerant using example 20 did not exhibit at least a 2% improvement in any of the heat exchanger effectiveness values, and while examples 21 and 22 exhibited at least a 2% improvement in 75% and 85% of the heat exchanger effectiveness values, as shown in table 20/25-DT, these heat exchanger effectiveness values did not provide acceptable discharge, and the refrigerant was not suitable for such conditions.
The present application may include the following technical solutions.
1. A heat transfer system for cooling the contents of an enclosure, comprising:
(a) a relatively low temperature vapor compression circuit comprising a compressor, an expander and an evaporator in fluid communication in said circuit, and a first heat transfer composition comprising a first refrigerant and a compressor lubricant in said circuit, said evaporator being located in said housing and capable of absorbing heat from fluid in said housing at about said relatively low temperature;
(b) a relatively high temperature vapor compression circuit comprising a compressor, a condenser, an expander and a suction line heat exchanger in fluid communication in said circuit, and a second heat transfer composition comprising a second refrigerant and preferably a compressor lubricant in said circuit, said condenser being capable of transferring heat to a heat sink located outside said shell; and
(c) a cascade heat exchanger for condensing the first refrigerant and evaporating the second refrigerant by heat exchange between the first and second refrigerants,
wherein the suction line heat exchanger is in fluid communication with the cascade heat exchanger to receive at least a portion of the second heat transfer composition exiting the cascade heat exchanger and to increase the temperature of the second heat transfer composition by absorbing heat from the first heat transfer composition exiting the condenser and thereby decrease the temperature of the first heat transfer composition before the first heat transfer composition enters the first loop expander.
2. The system of scheme 1, wherein the first refrigerant has a flammability classified as a1 (as measured by ASTM E681) according to ASHRAE 34 and the second refrigerant has a flammability classified as A2L (as measured by ASTM E681) according to ASHRAE 34 or a flammability greater than A2L.
3. The system of scheme 1, wherein the compressor and the expander and the condenser are each not located in the housing.
4. The system of scheme 5, wherein the suction line heat exchanger is not located in the housing.
5. The system of scheme 1, wherein the second refrigerant comprises one or more of: trans-1, 3,3, 3-tetrafluoropropene (HFO-1234ze (E)), 2,3,3, 3-tetrafluoropropene (HFO-1234yf), R-227ea, R-32, and combinations of two or more of these.
6. The system of scheme 1 wherein the second refrigerant comprises at least about 80 weight percent 2,3,3, 3-tetrafluoropropene (HFO-12304 yf).
7. The system of scheme 1 wherein said second refrigerant consists essentially of HFO-1234ze (e), HFO-1234yf, or a combination of these.
8. The system of scheme 1, wherein the second refrigerant comprises from about 70 wt.% to about 90 wt.% HFO-1234yf and from about 10 wt.% to about 30 wt.% R32.
9. The system of scheme 1 wherein the second refrigerant comprises from about 70 to about 90 wt.% HFO-1234yze (e) and from about 10 to about 30 wt.% R32.
10. The system of scheme 1 wherein said second refrigerant comprises from about 85% to about 90% by weight trans 1,3,3, 3-tetrafluoropropene (HFO-1234ze (e)) and from about 10% to about 15% by weight 1,1,1,2,3,3, 3-heptafluoropropane (HFC-227 ea).
Claims (13)
1. A heat transfer system comprising an enclosure, the system for cooling the contents of the enclosure, the system further comprising:
(a) a relatively low temperature vapor compression circuit comprising a compressor, an expander and an evaporator in fluid communication in said circuit, and a first heat transfer composition comprising a first refrigerant and a compressor lubricant in said circuit, said evaporator being located in said housing and capable of absorbing heat from fluid in said housing at about said relatively low temperature, wherein said first refrigerant consists essentially of carbon dioxide;
(b) a relatively high temperature vapor compression circuit comprising a compressor, a condenser, an expander and a suction line heat exchanger in fluid communication in said circuit, and a second heat transfer composition comprising a second refrigerant and preferably a compressor lubricant in said circuit, said condenser being capable of compressing heat to a location external to said circuitA heat sink external to the shell to transfer heat, wherein the second refrigerant has a specific CO2The flammability is large; and
(c) a cascade heat exchanger for condensing the first refrigerant and evaporating the second refrigerant by heat exchange between the first and second refrigerants,
wherein the suction line heat exchanger is in fluid communication with the cascade heat exchanger to receive at least a portion of the second heat transfer composition exiting the cascade heat exchanger and to raise the temperature thereof by absorbing heat from the second heat transfer composition exiting the condenser and thereby reduce the temperature of the second heat transfer composition before it enters the relatively high temperature vapor compression loop expander,
wherein the capacity of the system is less than 30kW, and
wherein the second refrigerant consists essentially of R-1234ze (e) and the charge weight ratio of first refrigerant to the second refrigerant in the low temperature loop is not less than about 1.2; or
Wherein the second refrigerant consists essentially of R-1234ze (E) and R-32 and the charge weight ratio of the first refrigerant to the second refrigerant in the low temperature loop is not less than about 1.0; or
Wherein the second refrigerant consists essentially of R-32 and the charge weight ratio of the first refrigerant to the second refrigerant in the low temperature loop is not less than about 0.9; or
Wherein the second refrigerant comprises from about 70 wt.% to about 90 wt.% of HFO-1234yf and from about 10 wt.% to about 30 wt.% of R32.
2. The system of claim 1, wherein the compressor and the expander and the condenser are each not located in the housing.
3. The system of claim 1, wherein the enclosure is for keeping items cold by cooling air in the enclosure, and wherein the enclosure is selected from the group consisting of walk-in refrigerators, freezers, and transport freezers.
4. The system of any of claims 1-3, wherein the capacity of the system is less than 15 kW.
5. The system of any of claims 1-3, wherein the capacity of the system is less than 10 kW.
6. A system according to any one of claims 1 to 5, wherein the second refrigerant consists essentially of R-1234ze (E) and the charge weight ratio of first refrigerant to the second refrigerant in the low temperature loop is not less than about 1.2.
7. A system according to any one of claims 1 to 5, wherein the second refrigerant consists essentially of R-1234ze (E) and R-32 and the charge weight ratio of first refrigerant to the second refrigerant in the cryogenic circuit is not less than about 1.0.
8. The system of any of claims 1-5, wherein the second refrigerant consists essentially of R-32 and the charge weight ratio of first refrigerant to the second refrigerant in the low temperature loop is not less than about 0.9.
9. The system according to any one of claims 1-5, wherein the second refrigerant comprises from about 70 wt.% to about 90 wt.% of HFO-1234yf and from about 10 wt.% to about 30 wt.% of R32.
10. A method of recapturing heat transfer fluid that escapes to the atmosphere over time.
11. A refrigerant comprising at least about 50% by weight trans-1, 3,3, 3-trifluoropropene (HFO-1234ze (E)) and/or HFO-1234yf, and the refrigerant having a flammability greater than CO2Is combustible.
12. A refrigeration lubricant for use with Hydrofluorocarbon (HFC) refrigerants in refrigeration machinery, selected from the group consisting of polyol esters (POE), polyalkylene glycols (PAG), silicone oils, mineral oils, Alkylbenzenes (AB) and poly (alpha-olefins) (PAO).
13. A walk-in cold room refrigeration system includes an evaporator, an expander, a compressor, and a condenser.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201662313177P | 2016-03-25 | 2016-03-25 | |
| US62/313177 | 2016-03-25 | ||
| CN201780019272.8A CN108779940A (en) | 2016-03-25 | 2017-03-24 | Low GWP cascade refrigeration systems |
| PCT/US2017/024010 WO2017165764A1 (en) | 2016-03-25 | 2017-03-24 | Low gwp cascade refrigeration system |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201780019272.8A Division CN108779940A (en) | 2016-03-25 | 2017-03-24 | Low GWP cascade refrigeration systems |
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| EP3433547A1 (en) | 2019-01-30 |
| EP3433547A4 (en) | 2019-10-02 |
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