CN114061163A

CN114061163A - Multi-stage low GWP air conditioning system

Info

Publication number: CN114061163A
Application number: CN202110993068.4A
Authority: CN
Inventors: A·塞蒂; S·F·亚纳莫塔; E·d·C·贝拉韦塞拉
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2016-02-16
Filing date: 2017-02-16
Publication date: 2022-02-18
Also published as: EP3417215A1; CN117213084A; EP4365513A2; EP4365513A3; EP3417215A4; CN109073284A; CN117249595A

Abstract

The present application relates to a multi-stage low GWP air conditioning system. A refrigerant system for conditioning air and/or goods located in a dwelling occupied by humans or other animals is disclosed, the refrigerant system preferably comprising: at least a first heat transfer loop containing a first heat transfer fluid in the form of a vapor/compression cycle loop located substantially outside of the dwelling; and at least a second heat transfer loop comprising a second heat transfer fluid different from the first heat transfer fluid, located substantially inside the dwelling.

Description

Multi-stage low GWP air conditioning system

The application is a divisional application of an invention patent application with application date of 2018, 10 and 15, application number of 201780023799.8 and invention name of a multistage low GWP air conditioning system.

Technical Field

The present invention relates to efficient low global warming potential ("low GWP") air conditioning and related refrigeration systems and methods that are safe and effective.

Background

In typical air conditioning and refrigerant 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). In the condenser, the vapor is condensed (at least to a large extent) to produce a liquid heat transfer fluid at a relatively high pressure. Typically, the condenser uses a large amount of available fluid in the ambient environment (such as ambient outside air) as a heat sink. Once it has been condensed, the high pressure heat transfer fluid undergoes a substantially isenthalpic expansion, such as by passing through an expansion device or expansion valve where it is expanded to a lower pressure, which in turn causes the fluid to undergo a reduction in temperature. The low pressure, low temperature heat transfer fluid from the expansion operation is then typically routed to an evaporator where it absorbs heat and evaporates in doing so. This evaporation process in turn leads to cooling of the fluid or body intended to be cooled. In a typical air conditioning application, the cooled fluid is room air of an air-conditioned dwelling. In a refrigeration system, cooling may include cooling air inside a cold box or storage unit. After the heat transfer fluid is evaporated at low pressure in the evaporator, it returns to the compressor where the cycle begins again.

A complex and relevant combination of factors and requirements is associated with creating an efficient, effective and safe air conditioning system that is simultaneously environmentally friendly, that is, has both low GWP impact and low ozone depletion ("ODP") impact. With respect to efficiency and effectiveness, it is important that the heat transfer fluid operate in an air conditioning system with a high level of efficiency and high capacity. At the same time, since it is possible that the heat transfer fluid may escape into the atmosphere over time, it is important that the fluid have both low GWP values and low ODP values.

While certain fluids are capable of achieving both high levels of efficiency and effectiveness, and simultaneously low levels of both GWP and ODP, applicants have come to appreciate that many fluids meeting this combination of requirements suffer from drawbacks related to safety. For example, fluids that might otherwise be acceptable may be disadvantageous for use due to flammability properties and/or toxicity issues. The applicant has come to appreciate that the use of fluids of these properties is particularly undesirable in typical air conditioning systems, as such flammable and/or toxic fluids may be inadvertently released into a cooled dwelling (or heated in the case of heat pump applications), thus exposing or potentially exposing occupants thereof to hazardous conditions.

Disclosure of Invention

In accordance with one aspect of the present invention, a refrigerant system for conditioning air and/or items located in a dwelling occupied by a human or other animal is provided. A preferred embodiment of such a system comprises at least a first heat transfer loop, preferably comprising a first heat transfer fluid in the form of a vapor/compression cycle loop, which is located substantially outside the dwelling. This first loop is sometimes conveniently referred to herein as an "outdoor loop". The outdoor loop preferably includes a compressor, a heat exchanger for condensing a heat transfer fluid in the outdoor loop, preferably by heat exchange with outdoor ambient air, and an expansion device. The preferred system also includes at least a second heat transfer loop containing a second heat transfer fluid different from the first heat transfer fluid, which is located substantially inside the dwelling. This second loop is sometimes conveniently referred to herein as an "indoor loop". The indoor loop preferably comprises an evaporator heat exchanger for evaporating the second heat transfer fluid in the indoor loop, preferably by heat exchange with the indoor air. In a preferred embodiment, the second heat transfer loop does not include a vapor compressor.

The preferred system preferably includes at least one intermediate heat exchanger that permits heat exchange between the first heat transfer fluid and the second heat transfer fluid such that heat is transferred to the first heat transfer fluid, preferably thereby evaporating the first heat transfer fluid, and heat is transferred from the second heat transfer fluid, thereby condensing the second heat transfer fluid. Preferably, the intermediate heat exchanger is located outside the dwelling or outside the area where the air is conditioned.

An important aspect of the preferred system is that the first heat transfer fluid 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 the second heat transfer fluid comprises a refrigerant also having a GWP of no greater than about 500 (more preferably no greater than about 400, and even more preferably less than 150), and that the refrigerant has low flammability and low toxicity, and even more preferably is substantially less than the flammability of the refrigerant in the first heat transfer fluid and/or substantially less than the toxicity of the refrigerant in the first heat transfer fluid.

In a preferred embodiment, the first heat transfer fluid comprises a refrigerant having a GWP of no greater than about 500, and the second heat transfer fluid comprises a refrigerant also having a GWP of no greater than about 500, and the refrigerant has a flammability substantially less than the flammability of the refrigerant in the first heat transfer fluid and/or a toxicity substantially less than the toxicity of the refrigerant in said first heat transfer fluid.

In a preferred embodiment, the first heat transfer fluid comprises a refrigerant having a GWP of no greater than about 400, and the second heat transfer fluid comprises a refrigerant also having a GWP of no greater than about 400, and the refrigerant has a flammability substantially less than the flammability of the refrigerant in the first heat transfer fluid and/or a toxicity substantially less than the toxicity of the refrigerant in said first heat transfer fluid.

In a preferred embodiment, the first heat transfer fluid comprises a refrigerant having a GWP of no greater than about 150, and the second heat transfer fluid comprises a refrigerant also having a GWP of no greater than about 150, and the refrigerant has a flammability substantially less than the flammability of the refrigerant in the first heat transfer fluid and/or a toxicity substantially less than the toxicity of the refrigerant in said first heat transfer fluid.

In a preferred embodiment, the second refrigerant comprises, more preferably comprises, at least about 50% by weight and even more preferably at least about 75% by weight trans-1-chloro-3, 3, 3-trifluoropropene (HCFO-1233 zd (e)), and the first refrigerant has a flammability greater than (and preferably substantially greater than) the flammability of HCFO-1233zd (e).

In a preferred embodiment, the second refrigerant comprises, more preferably comprises, at least about 75% by weight and even more preferably at least about 80% by weight trans-1-chloro-3, 3, 3-trifluoropropene (HCFO-1233 zd (e)), and the first refrigerant has a flammability greater than (and preferably substantially greater than) the flammability of HCFO-1233zd (e).

Drawings

FIG. 1 is a general process flow diagram of a preferred embodiment of an air conditioning system according to the present invention.

Fig. 2 is a general process flow diagram of another preferred embodiment of an air conditioning system according to the present invention.

Fig. 3 is a general process flow diagram of another preferred embodiment of an air conditioning system according to the present invention.

FIG. 4 is a schematic representation of a heat exchanger according to an embodiment of the present invention.

FIG. 5 is a general process flow diagram of another preferred embodiment of an air conditioning system according to the present invention that can operate with both cooling and heating.

Detailed Description

Preferred Heat transfer Components

In various embodiments described herein, a system includes a first heat transfer composition including a first refrigerant and preferably a lubricant for a compressor and a second heat transfer composition including a second refrigerant. Preferably, the second refrigerant, which comprises at least about 50% by weight, more preferably at least about 80% by weight trans 1-chloro-3, 3, 3-trifluoropropene (HCFO-1233 zd (e)) or at least about 75% by weight, more preferably at least about 80% by weight trans 1,3,3, 3-tetrafluoropropene (HFO-1234 ze (e)), is a low flammability and low toxicity refrigerant, preferably having a level a toxicity and a level 1 or 2L flammability according to ASHRAE standard 34. In highly preferred embodiments, the second refrigerant comprises at least about 95% by weight HFCO-1233zd (e), and in some embodiments consists essentially of, or consists of, HFCO-1233ze (e).

In a highly preferred embodiment, the second refrigerant comprises from about 95% to about 99% by weight of a five-carbon saturated hydrocarbon, preferably one or more of isopentane (iso-pentane), n-pentane (n-pentane), or neopentane (neo-pentane), and in a preferred aspect of such an embodiment, the combination of the HFCO-1233zd (e) and the pentane is in the form of an azeotropic composition.

In highly preferred embodiments, the second refrigerant comprises from about 85 to about 90% by weight trans 1,3,3, 3-tetrafluoropropene (HFO-1234 ze (e)) and from about 10 to about 15% by weight 1,1,1,2,3,3, 3-heptafluoropropane (HFC-227 ea), and in some embodiments even more preferably about 88% by weight trans 1,3,3, 3-tetrafluoropropene (HFO-1234 ze (e)) and about 12% by weight 1,1,1,2,3,3, 3-heptafluoropropane (HFC-227 ea).

In highly preferred embodiments, the second refrigerant comprises from about greater than about 50% by weight to about 67.5% by weight trans 1,3,3, 3-tetrafluoropropene (HFO-1234 ze (e)) and from greater than about 9.7% to less than about 50% by weight HFCO-1233zd (e), and in some embodiments even more preferably about 67% by weight trans 1,3,3, 3-tetrafluoropropene (HFO-1234 ze (e)) and about 33% by weight HFCO-1233zd (e). The applicant has found that such preferred embodiments are unexpectedly able to provide a second refrigerant which is instantly non-flammable according to ASHRAE standard 34 (which measures the flammability of the initial vapour from the fractionation of the mixture as would occur in case of a refrigerant leak) and which also produces a pressure higher than about 1bar in the indoor loop of the refrigeration system.

Those skilled in the art will appreciate, in view of the disclosure contained herein, that such embodiments of the present invention provide the following advantages: only relatively safe (low toxicity and low flammability) low GWP refrigerants are used, making them highly preferred for use in locations close to occupied humans or other animals, as would typically be encountered in air conditioning applications.

Preferably, in a preferred embodiment, the first refrigerant may include one or more components that may render the refrigerant substantially less desirable than the second refrigerant from a toxicity and/or flammability standpoint, and all such first refrigerants are included within the scope of the present invention. For example, the first refrigerant may comprise one or more mixtures comprising one or more of: HFC-32 (preferably in an amount of from about 0% to about 22% by weight), HFO-1234ze (preferably in an amount of from about 0% to about 78% by weight), HFO-1234yf (preferably in an amount of from about 0% to about 78% by weight), and propane. In contrast to the first heat transfer component, the second heat transfer component of the present invention generally does not include a lubricant because the fluid does not need to pass through the compressor.

The first heat transfer component also typically includes a lubricant, a heat transfer component, typically in an amount of from about 30% to about 50% by weight based on the total weight of the refrigerant, and other optional components present in the system. Other optional components include compatibilizers, such as propane, which are used for the purpose of aiding compatibility and/or solubility of the lubricant. When present, such compatibilizers (including propane, butane, and pentane) are preferably present in amounts of from about 0.5% to about 5% by weight of the ingredients. Combinations of surfactants and solubilizers may also be added to the current ingredients 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 such as Polyol esters (POE) and polyalkylene glycols (PAG), silicone oils, mineral oils, Alkylbenzenes (AB), and Poly (alpha-olefins), which are used in refrigeration machines having Hydrofluorocarbon (HFC) refrigerants, may be used with the refrigerant composition of the present invention. The preferred lubricant is POE.

Embodiment of the type illustrated in fig. 1

In the following description, components or elements of the system that are or may be substantially the same or similar in different embodiments are designated with the same reference numerals or labels.

A preferred air conditioning system is illustrated in fig. 1, generally designated 10, wherein the dashed lines represent the approximate boundary between an indoor loop and an outdoor loop, with the compressor 11, condenser 12, intermediate heat exchanger 13 and expansion valve 14, along with any of the associated

conduits

15 and 16 and other connections and related equipment (not shown), located outdoors. The outdoor loop (which is sometimes also referred to herein as a "high temperature refrigerant circuit") preferably comprises a first heat transfer component, preferably according to one or more of the preferred embodiments described above, comprising a first refrigerant and a lubricant for the compressor, wherein at least the first refrigerant circulates in the circuit through

conduits

15 and 16 and other related conduits and equipment.

The indoor loop (which is sometimes also referred to herein as a "cryogenic refrigerant circuit") preferably comprises at least a second heat transfer component comprising a second refrigerant, wherein the second refrigerant has at least one safety property (such as flammability and toxicity) that is superior to the corresponding safety property of the first refrigerant. In a highly preferred embodiment, the second refrigerant preferably has sufficiently low toxicity (designated as class a according to ASHRAE standard 34) and preferably also sufficiently low flammability so as to have a class 1 or class 2L flammability rating. In a highly preferred embodiment, the second refrigerant comprises (and in some embodiments consists essentially of): HFCO-1233zd, and even more preferably trans HFCO-1233 zd. In other highly preferred embodiments, the second refrigerant comprises (and in some embodiments consists essentially of, and in some embodiments consists of): HFO-1234ze (E) and 1,1,1,2,3,3, 3-heptafluoropropane (HFC-227 ea). Those skilled in the art will appreciate, in view of the disclosure contained herein, that such embodiments of the present invention provide the following advantages: only relatively safe (low toxicity and low flammability) low GWP refrigerants, such as HFCO-1233zd (e) and HFO-1234ze (e)/HFC-227 ea, are used in close proximity to humans or other animals occupying the dwelling or entering the space being conditioned, while humans or animals that are or may be in the dwelling or conditioned space are separated from the first refrigerant. Accordingly, the preferred configuration and selection of refrigerants allows for the provision of systems that benefit from the use of refrigerants having many desirable properties, such as capacity, efficiency, low GWP and low ODP, but while possessing one or more properties that may otherwise make them highly undesirable and/or prevent their use in close proximity to humans or other animals at restricted and/or enclosed locations. Such a combination provides excellent advantages in terms of all desired properties for such refrigerant systems.

In a preferred embodiment, for example, the first refrigerant may comprise one or more mixtures comprising one or more of: HFC-32 (preferably in an amount of from about 0% to about 22% by weight), HFO-1234ze (preferably in an amount of from about 0% to about 78% by weight), HFO-1234yf (preferably in an amount of from about 0% to about 78% by weight), and propane.

The heat transfer fluid in the outdoor circuit will typically and preferably include a lubricant for the compressor, typically in an amount of from about 30% to about 50% by weight of the heat transfer fluid, with the remainder including the refrigerant and other optional components that may be present. Other optional components include compatibilizers, such as propane, which are used for the purpose of aiding compatibility and/or solubility of the lubricant. When present, such compatibilizers (including propane, butane, and pentane) are preferably present in amounts of from about 0.5% to about 5% by weight of the ingredients. Combinations of surfactants and solubilizers may also be added to the current ingredients 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 such as polyol esters (POE) and polyalkylene glycols (PAG), silicone oils, mineral oils, Alkylbenzenes (AB), and poly (alpha-olefins) (PAO), which are used in refrigeration machinery with Hydrofluorocarbon (HFC) refrigerants, may be used with the refrigerant compositions of the present invention. The preferred lubricant is POE.

In operation, a second refrigerant according to the present invention is circulated through the circuit by flowing through the intermediate heat exchanger 13, wherein it transfers heat to the first refrigerant and, in so doing, condenses at least a portion of the second refrigerant, and preferably substantially all of the second refrigerant, into liquid form, where it exits the intermediate heat exchanger through conduit 17. In a preferred embodiment, the second refrigerant leaving the intermediate heat exchanger enters the receiver 18, and a liquid reservoir of the second refrigerant is disposed in the receiver 18. Although the receiver 18 is shown in this figure as being located indoors, the container may also be located outdoors, and it may also be preferable to locate the pump 20 (when present) outdoors. The liquid refrigerant from the separation vessel is led to the evaporator via a conduit 21. In the view shown in fig. 1, a liquid pump 20 is shown to assist in transporting liquid refrigerant through

conduits

21, 22 and valve 23 to an evaporator 24. However, in other embodiments, other means or techniques that can be used alone or in combination with a liquid pump can be used to transport the second refrigerant liquid from the receiver. For example, in some embodiments, the transport of the liquid refrigerant may be accomplished by using a liquid gravity feed to the evaporator, while in other embodiments, a thermosiphon arrangement may be used to transport the second liquid refrigerant to and from the evaporator 24 to the intermediate heat exchanger 13.

In a preferred embodiment, wherein the refrigerant comprises (preferably consists essentially of, and preferably consists of) at least about 90% by weight of HCFO-1233zd (e) or HFO-1234ze (e), the operating conditions correspond to the values described in the following table.

Embodiment of the type illustrated in fig. 2

Another preferred embodiment of the invention is illustrated in fig. 2, wherein the compressor 11, condenser 12, intermediate heat exchanger 13, expansion valve 14, and suction line heat exchanger 30 are located outdoors along with any of the associated

conduits

15A, 15B, 16A and 16B and other connections and related equipment (not shown). The outdoor loop (which is sometimes referred to herein as a "high temperature refrigerant loop") preferably includes a first heat transfer composition comprising a first refrigerant and a lubricant for the compressor, wherein at least the refrigerant circulates in the loop through

conduits

17, 19, 21, and 22 and other related conduits and equipment.

The indoor loop is configured substantially as described above for the indoor loop of fig. 1, and the first and second heat transfer compositions are preferably also as indicated herein.

In operation, a first refrigerant according to the present invention is discharged from the compressor 11 as a relatively high pressure refrigerant vapor, which may include entrained lubricant, and which then enters the condenser 12 where it transfers heat to (preferably) ambient air and at least partially condenses. The refrigerant effluent from condenser 12 is transported via conduit 15A to suction line heat exchanger 30 where additional heat is lost to the effluent from intermediate heat exchanger 13. The effluent from the suction/liquid line heat exchanger 30 is then transported via conduit 15B to the expansion valve 14 where the pressure of the refrigerant is reduced, which in turn reduces the temperature of the refrigerant. The relatively cool liquid refrigerant from the expansion valve then enters the intermediate heat exchanger 13 where it picks up heat from the second refrigerant vapor leaving the evaporator 24 in the indoor loop. The first refrigerant effluent vapor from the intermediate heat exchanger is then transported via conduit 16A to a suction/liquid line heat exchanger 30, which here takes heat from the condenser effluent from conduit 15A and produces a second refrigerant vapor at a higher temperature, which is transported by conduit 16B to the inlet of compressor 11.

The evaporator effluent is transported via conduit 19 to the intermediate heat exchanger 13 where heat is lost to the effluent from the suction line heat exchanger, which is transported via conduit 15B to the intermediate heat exchanger, and a relatively cool second refrigerant stream is produced. This cold stream of the second refrigerant exiting from the intermediate heat exchanger 13 is transported to a receiver tank 18, which receiver tank 18 provides a reservoir of cold liquid refrigerant which is transported from the tank via a conduit 21 and which is then fed into an evaporator 24 through a control valve 23. In some embodiments, a pump 20 is provided for providing a flow of liquid to the control valve 23. The ambient air to be cooled loses heat to the cold liquid refrigerant in the evaporator 24, which in turn evaporates the liquid refrigerant and produces refrigerant vapor with little or no superheat, and the vapor then flows back to the intermediate heat exchanger 13.

Embodiment of the type illustrated in fig. 3

Another preferred embodiment of the invention is illustrated in fig. 3, wherein the two-stage compressor 11, condenser 12, intermediate heat exchanger 13, expansion valve 14, and vapor injection heat exchanger 40 (including associated intermediate expansion valve 41) are located outdoors along with any of the associated conduits 15A-15 and other connections and related equipment (not shown and/or labeled). The outdoor loop (which is sometimes referred to herein as a "high temperature refrigerant loop") preferably includes a first heat transfer composition comprising a first refrigerant and a lubricant for the compressor, wherein at least the refrigerant circulates in the loop through

conduits

15 and 16 and other related conduits and equipment.

In operation, a first refrigerant according to the present invention (which may include entrained lubricant) is discharged from the compressor 11 as a relatively high pressure refrigerant vapor, which may include entrained lubricant, and which then enters the condenser 12 where it transfers heat to (preferably) ambient air and at least partially condenses. The effluent stream from condenser 12 at least partially, and preferably substantially completely, comprises condensed refrigerant. The refrigerant effluent from condenser 12 is transported via conduit 15A, and a portion of the refrigerant effluent is routed to intermediate expansion device 41 via conduit 15B, and another portion of the effluent (preferably the remainder of the effluent) is transported to vapor injection heat exchanger 40.

Intermediate expansion device 41 reduces the pressure of the effluent stream (preferably substantially isenthalpically) to about the pressure of the second stage suction of compressor 11 or sufficiently above such pressure to account for the pressure drop through heat exchanger 41 and associated conduits, fixtures, and the like. Due to the pressure drop across expansion device 41, the pressure of the refrigerant flowing to heat exchanger 40 decreases relative to the temperature of the high pressure refrigerant flowing to heat exchanger 40. In the heat exchanger 40, heat is transferred from the high pressure stream to the stream passing through the expansion valve 41. Thus, the intermediate pressure stream exiting heat exchanger 40 is at a higher temperature than the inlet stream, thereby producing a superheated steam stream that is transported to the second stage of compressor 11 via conduit 19C.

As the higher pressure stream transported through conduit 15A travels through heat exchanger 40, it loses heat to the lower pressure stream exiting expansion valve 41 and exits the heat exchanger through conduit 15C, and then flows to expansion valve 14 and then onwards to the intermediate heat exchanger where it picks up heat and is transported to the first stage of compressor suction.

Embodiment of the type illustrated in fig. 5

The embodiment disclosed in fig. 5 is similar to the embodiment of fig. 1 except that the system is equipped with a reversing valve so that it can operate in a heating mode, as described below.

A preferred air conditioning system operable in both cooling and heating modes is illustrated in fig. 1, generally designated 10, wherein the indicated lines represent approximate boundaries between an indoor loop and an outdoor loop, with the compressor 11, outdoor coil 12, intermediate heat exchanger 13, expansion valve 14 and reversing valve 500 located outdoors along with any of the associated

conduits

15 and 16 and other connections and related equipment (not shown). The outdoor loop preferably comprises a first heat transfer component, preferably according to one or more of the preferred embodiments described above, comprising a first refrigerant and a lubricant for the compressor, wherein at least the first refrigerant circulates in the loop through

conduits

15 and 16 and other related circuits and equipment.

The indoor loop preferably comprises at least a second heat transfer component comprising a second refrigerant, wherein the second refrigerant has at least one safety property (such as flammability and toxicity) that is superior to the corresponding safety property of the first refrigerant. In a highly preferred embodiment, the second refrigerant preferably has sufficiently low toxicity (designated as class a according to ASHRAE standard 34) and preferably also sufficiently low flammability so as to have a class 1 or class 2L flammability rating. In a highly preferred embodiment, the second refrigerant comprises (and in some embodiments consists essentially of): HFCO-1233zd, and even more preferably trans HFCO-1233 zd. In other highly preferred embodiments, the second refrigerant comprises (and in some embodiments consists essentially of, and in some embodiments consists of): HFO-1234ze (E) and 1,1,1,2,3,3, 3-heptafluoropropane (HFC-227 ea). Those skilled in the art will appreciate, in view of the disclosure contained herein, that such embodiments of the present invention provide the following advantages: only relatively safe (low toxicity and low flammability) low GWP refrigerants, such as HFCO-1233zd (e) and HFO-1234ze (e)/HFC-227 ea, are used in close proximity to humans or other animals occupying the dwelling or entering the space being conditioned, while humans or animals that are or may be in the dwelling or conditioned space are separated from the first refrigerant. Accordingly, the preferred configuration and selection of refrigerants allows for the provision of systems that benefit from the use of refrigerants having many desirable properties, such as capacity, efficiency, low GWP and low ODP, but while possessing one or more properties that may otherwise make them highly undesirable and/or prevent their use in close proximity to humans or other animals at restricted and/or enclosed locations. Such a combination provides excellent advantages in terms of all desired properties for such refrigerant systems.

In operation, according to the fig. 5 heating mode embodiment of the invention, the second refrigerant circulates through the circuit by flowing through the intermediate heat exchanger 13, where it picks up heat from the first refrigerant and in so doing evaporates at least a portion (and preferably substantially all) of the second refrigerant into vapor form, where it exits the intermediate heat exchanger through conduit 17. The vaporized refrigerant is directed via conduit 21 to a condenser where it rejects heat to the dwelling upon condensation. In the view shown in fig. 1, a liquid pump 20 is shown to assist in transporting liquid refrigerant through

conduits

21, 22 and valve 23 to a condenser 24. In addition, the indoor loop also includes a reversing valve 501, the reversing valve 501 allowing the system to operate in both heating and cooling modes.

In a preferred embodiment, wherein the refrigerant comprises (preferably consists essentially of, and preferably consists of) at least about 90% by weight of HCFO-1233zd (e) or HFO-1234ze (e).

Examples of the invention

Comparative example 1

An air conditioning system according to a typical arrangement using R-410A as the refrigerant operates according to the following parameters:

operating Condition-basic cycle of R410A

1. Condensation temperature =45 ℃, corresponding to an outdoor ambient temperature =35 ℃

2. Condensation temperature-ambient temperature =10 deg.c

3. Sub-cooling of expansion device =5.0 deg.C

4. The evaporation temperature =7 ℃, corresponding to room temperature =27 DEG C

5. Evaporator superheat =5.0 deg.c

6. Isentropic efficiency =72%

7. Volume efficiency =100%

The capability and COP of the system are determined and used as baseline values for determining the relative capability and COP in the following example.

Example 1A

Example 1A (FIG. 1) operating conditions

A system configured as illustrated herein in fig. 1 operates using a series of different first (outdoor) and second (indoor) refrigerants in accordance with the following operating parameters:

2. Condensation temperature-ambient temperature =10 deg.c

3. Expansion device subcooling =5.0 deg.c

5. Evaporator superheat =0.0 ℃ (flooded)

6. Superheat =5.0 ℃ of intermediate heat exchanger

7. Isentropic efficiency =72%

8. Volume efficiency =100%

9. The difference in the intermediate heat exchanger saturation temperature =5 deg.c

The results are provided in table 1A below (the percentage of the mixture is shown in wt%).

Table 1A

As can be seen from the above results, each air conditioning system according to the present invention is capable of providing an accurate capability matching that of an existing R410A air conditioning system operating as indicated and a COP (efficiency) of at least 85% in all cases relative to such an existing system. Importantly, in all cases, the system used refrigerants each having a GWP of less than 150, which is an improvement of about 10 times for R-410A based refrigeration systems. This combination of properties can be achieved, which is a highly beneficial but unexpected result.

Example 1B (FIG. 1) operating conditions

A system configured as illustrated herein in fig. 1 operates according to the same operating parameters using a series of different first (outdoor) and second (indoor) refrigerants, except that the condensing temperature is adjusted for each mixture in order to obtain an efficiency that substantially matches that achieved according to comparative example 1. The results are provided in table 1B below.

Table 1B

The above results indicate that a system according to the present invention can be implemented with only relatively small changes in condenser temperature, which produces an efficiency that substantially matches that of an R-410A based system. As an alternative, without reducing or changing the comparative condenser temperature, the efficiency according to the present method is preferably increased by slightly increasing the heat transfer area in the condenser compared to the amount of heat transfer area in the condenser using the comparative R-410A system. Furthermore, the system according to fig. 2 using a suction line heat exchanger shows a favorable improvement in efficiency even compared to the configuration of the invention without such a heat exchanger as reported in example 1A.

Example 1C (FIG. 1) -Change in environmental conditions

A system configured as illustrated herein in fig. 1 operates according to the same operating parameters as example 1A using a series of different first (outdoor) refrigerants and second (indoor) refrigerants, except that the ambient temperature is adjusted to 35 ℃, 45 ℃ and 55 ℃ for each mixture. The results are provided in table 1C below.

Table 1C

The above results indicate that embodiments according to the present invention can provide superior performance when ambient temperature rises above 35 ℃ compared to the R-410A system.

Example 2A

Example 2A (FIG. 2) operating conditions

A system configured as illustrated herein in fig. 2 operates using a series of different first (outdoor) and second (indoor) refrigerants in accordance with the following operating parameters:

2. Condensation temperature-ambient temperature =10 deg.c

3. Expansion device subcooling =5.0 deg.c

5. Evaporator superheat =0.0 ℃ (flooded)

6. Superheat =5.0 ℃ of intermediate heat exchanger

7. Isentropic efficiency =72%

8. Volume efficiency =100%

The results are provided in table 2A below (the percentage of the mixture is shown in wt%).

Table 2A

As can be seen from the above results, each air conditioning system according to the present invention is capable of providing an accurate capacity matching that of an existing R410A air conditioning system operating as indicated and a COP (efficiency) of at least 90% in all cases relative to such an existing system. Importantly, in all cases, the system used refrigerants each having a GWP of less than 150, which is an improvement of about 10 times for R-410A based refrigeration systems. This combination of properties can be achieved, which is a highly beneficial but unexpected result.

Example 2B

Example 2B (FIG. 2) -Change in condenser temperature

A system configured as illustrated herein in fig. 2 operated according to the same operating parameters as example 2A using a series of different first (outdoor) and second (indoor) refrigerants, except that the condensing temperature was adjusted for each mixture in order to obtain an efficiency that substantially matches that achieved according to comparative example 1. The results are provided in table 2B below.

Table 2B

The above results indicate that a system according to the present invention can be implemented with only relatively small changes in condenser temperature, which produces an efficiency that substantially matches that of an R-410A based system. As an alternative, without reducing or changing the comparative condenser temperature, the efficiency according to the present method is preferably increased by slightly increasing the heat transfer area in the condenser compared to the amount of heat transfer area in the condenser using the comparative R-410A system.

Example 2C

Example 2C (FIG. 2) -Change in environmental conditions

A system configured as illustrated herein in fig. 2 operates according to the same operating parameters as example 2A using a series of different first (outdoor) and second (indoor) refrigerants, except that the ambient temperature is adjusted to 35 ℃, 45 ℃ and 55 ℃ for each mixture. The results are provided in table 2C below.

Table 2C

Example 3A

Example 3A (FIG. 3) operating conditions

The system configured as illustrated herein in fig. 3 operates by using a series of different first (outdoor) and 100% trans-HFCO-1233 zd as indoor refrigerant according to the following operating parameters:

2. Condensation temperature-ambient temperature =10 deg.c

3. Expansion device subcooling =5.0 deg.c

5. Evaporator superheat =0.0 ℃ (flooded)

6. Superheat =5.0 ℃ of intermediate heat exchanger

7. Isentropic efficiency of two stages =72%

8. Volume efficiency =100%

10. Steam jet heat exchanger efficiency =35%, 55%, 75%, 85%

The results are provided in table 3A below (the percentage of the mixture is shown in wt%).

Table 3A

Example 3B

Example 3B (FIG. 3) -Change in condenser temperature

A system configured as illustrated herein in fig. 3 operates according to the same operating parameters as example 3A by using a series of different first (outdoor) and 100% trans-HFCO-1233 zd as indoor refrigerant, except that the condensing temperature is adjusted for each mixture in order to obtain an efficiency that substantially matches that achieved according to comparative example 1. The results are provided in table 3B below.

Table 3B

Example 3C

Example 3C (FIG. 3) -Change in environmental conditions

A system configured as illustrated herein in fig. 3 was operated according to the same operating parameters as example 2A using a series of different first (outdoor) and second (indoor) refrigerants, except that the ambient temperature was adjusted to 35 ℃, 45 ℃ and 55 ℃ for each mixture. The results are provided in table 3C below.

Table 3C

Example 4

The air conditioning system of example 1 was operated with indoor refrigerant comprising various binary mixtures of trans HCFO-1233zd and transhfo-1234 ze using evaporator temperatures in the range of from about-1 ℃ to about 10 ℃, which typically encompass condenser temperatures used in many important air conditioning systems. The results of the testing are reported in table 4A below.

Table 4A

Applicants have found that a composition of transhfo-1234 ze in an amount of at least about 50% by weight (as shown above in table 4) permits the indoor circuit to operate at pressures greater than one atmosphere, thus avoiding the need for a purification system, while at the same time providing a sufficiently low system pressure to allow the use of relatively low cost vessels and conduits and/or advantageously avoiding refrigerant leaks that might otherwise occur in high pressure systems. In addition, applicants have tested the flammability of transHFO-1234 ze/transHCFO-1233 zd, the fractional flammability of the mixture (which is related to the flammability of the refrigerant in case of a leak in the system), and the results of this work are reported in Table 4B below.

Table 4B

Based on the results reported in table 4B above, applicants have found that liquid mixtures having more than 67% by weight transhfo-1234 ze are flammable when measured according to the fractionation test conducted in accordance with ASTM 34, and that the amount of transhfo-1234 ze of less than about 50% by weight (i.e., transhfco-1233 zd is greater than 50%) according to the results in table 4A creates the potential for negative system pressures.

EXAMPLE 5 compatibility with plastics useful in Low pressure systems

Applicants have tested the stability of various plastic materials when exposed to trans-HFCO-1233 zd as follows: samples of various plastics were immersed in trans-HFCO-1233 zd for up to two (2) weeks at room temperature (approximately 24 ℃ -25 ℃) under ambient pressure conditions, after which the samples were removed from the trans-HFCO-1233 zd and allowed to vent for up to 24 hours. The results are reported in table 5 below.

Table 5

As shown by the results in table 5 above, the average volume percent change for each tested plastic material was less than 5%.

Example 6

The air conditioning system of example 1 was operated under the following conditions: under this condition, there is an unintentional leak from the high temperature refrigerant (which is A2L refrigerant) to the low temperature non-flammable refrigerant, which includes any of the preferred low temperature refrigerants of the present invention, including according to ASHRAE 34: refrigerants comprising HFO-1234ze (E), HFCO-1233zd (E), and combinations of these. In this case, the A2L (moderately flammable) refrigerant mixes with the non-flammable cryogenic refrigerant in the event of an inadvertent leak inside the intermediate heat exchanger. The resulting mixture of cryogenic refrigerant (e.g., R1233zd (E)) and A2L refrigerant may eventually leak into the room. However, in many cases, leakage into the chamber will be of a non-combustible material. In certain embodiments, a hopper (accumulator) may be used in conjunction with appropriate controls to ensure that an appropriate charge ratio is maintained between the high and low sides to ensure a non-combustible mixture. It may also be possible to incorporate into the present system a device or devices that are capable of detecting leaks of flammable refrigerant into the indoor loop and releasing all such refrigerant to the exterior of the residence. One such leak detection system is disclosed in U.S. application 15/400,891 filed on 6/1/2017 and provisional application 62/275,382 filed on 6/1/2016, each of which is incorporated herein by reference.

Table 6 shows the charge ratio that prevents a dangerous situation inside the dwelling in case of a leakage event.

Table 6: leak event in intermediate heat exchanger

Comparative example 2

A reversible heat pump system according to a typical prior art arrangement using R-410A as the refrigerant operates in a heating mode according to the following parameters:

operating Condition-basic cycle of R410A

1. Condensation temperature =40 ℃, corresponding indoor room temperature =21.1 DEG C

2. Condensation temperature-ambient temperature =19 deg.c

3. Expansion device subcooling =5.0 deg.c

4. Evaporation temperature =0 ℃, corresponding to an outdoor ambient temperature =8.3 ℃

5. Evaporator superheat =5.0 deg.c

6. Isentropic efficiency =72%

7. Volume efficiency =100%

The capacity and COP of the system were determined and used as baseline values for determining the relative capacity and COP in examples 7A and 7B below according to the invention.

Example 7A

The system herein operates using a series of different first (outdoor) and second (indoor) refrigerants according to the following operating parameters:

2. Condensation temperature-ambient temperature =19 deg.c

3. Expansion device subcooling =5.0 deg.c

5. Evaporator superheat =0.0 ℃ (flooded)

6. Superheat =5.0 ℃ of intermediate heat exchanger

7. Isentropic efficiency =72%

8. Volume efficiency =100%

The results are provided in table 7A below (the percentage of the mixture is shown in wt%).

Table 7A

Example 7B (FIG. 5) operating conditions

A system configured as illustrated herein in fig. 5 operates according to the same operating parameters using a series of different first (outdoor) and second (indoor) refrigerants, except that the condensing temperature is adjusted for each mixture in order to obtain an efficiency that substantially matches that achieved according to comparative example 2. The results are provided in table 7B below.

Table 7B

Claims

1. A refrigeration system for cooling or heating air of a space occupied by a human being, or for cooling or heating an article located in the space occupied by the human being using the air in the space occupied by the human being, the system comprising:

(a) an outdoor refrigerant circuit comprising:

(i) an outdoor refrigerant having a GWP of less than about 500 flowing through at least a portion of the outdoor loop to reject or absorb heat into the system, wherein at least the portion of the outdoor loop through which the outdoor refrigerant flows is not located within a space occupied by the human being;

(ii) a phase change heat exchanger;

(iii) a compressor providing a vapor flow of the outdoor refrigerant; and

(iv) an intermediate heat exchanger in which at least a portion of the outdoor refrigerant flow absorbs or rejects heat; and

(b) an indoor refrigerant circuit comprising:

(i) an indoor refrigerant flowing through at least a portion of the indoor circuit to absorb heat from or reject heat to the space occupied by the human being, wherein at least the portion of the indoor circuit through which the indoor refrigerant flows is located within the space occupied by the human being, the indoor refrigerant comprising at least about 50% by weight of HCFO-1233zd (e) and: (1) is non-flammable according to ASHRAE standard 34, and (2) has an Occupational Exposure Limit (OEL) of greater than 400 and is classified as class a according to ASHRAE standard 34, and (3) has a GWP of less than about 500; and

(ii) the intermediate heat exchanger of the outdoor refrigerant circuit, wherein the outdoor refrigerant flow absorbs heat from or rejects heat to the indoor refrigerant.

2. A refrigeration system for cooling air of a space occupied by a human being or for cooling an article located in the space occupied by the human being using the air in the space occupied by the human being, the system comprising:

(a) a high temperature refrigerant circuit comprising:

(i) a high temperature refrigerant having a GWP of less than about 500 flowing through at least a portion of the high temperature circuit so as to reject heat from the system, wherein at least the portion of the high temperature circuit through which the high temperature refrigerant flows is not located within a space occupied by the human being;

(ii) a condenser providing at least a first condenser effluent stream comprising a liquid high temperature refrigerant stream at a first temperature;

(iii) an expansion valve fluidly connected to the liquid high temperature refrigerant flow from the condenser and providing a high temperature refrigerant flow at a second temperature lower than the first temperature;

(iv) a compressor providing a vapor stream comprising at least a portion of the refrigerant flowing to the condenser; and

(v) an intermediate heat exchanger in which at least a portion of the high temperature refrigerant stream from the expansion valve absorbs heat and which produces a vapor stream comprising the high temperature refrigerant, the vapor stream from the intermediate heat exchanger being in fluid communication with an inlet of the compressor; and

(b) a cryogenic refrigerant circuit comprising:

(i) a cryogenic refrigerant flowing through at least a portion of the low pressure circuit to absorb heat from the space occupied by the human, wherein at least the portion of the cryogenic circuit through which cryogenic refrigerant flows is located within the space occupied by the human, the cryogenic refrigerant comprising at least about 50% by weight of HCFO-1233zd (E) and: (1) is non-flammable according to ASHRAE standard 34, and (2) has an Occupational Exposure Limit (OEL) of greater than 400 and is classified as class a according to ASHRAE standard 34, and (3) has a GWP of less than about 500;

(ii) a holding tank containing at least a portion of the cryogenic refrigerant in a liquid state;

(iii) an evaporator fluidly connected to the hopper, the evaporator receiving liquid cryogenic refrigerant from the hopper and producing a flow of cryogenic refrigerant therefrom in a vapor state; and

(iv) the intermediate heat exchanger of the high temperature refrigerant circuit, wherein the flow of high temperature refrigerant from the expansion valve absorbs heat from the low temperature refrigerant vapor from the evaporator, the intermediate heat exchanger producing a liquid effluent stream comprising the low temperature refrigerant, the low temperature liquid effluent stream from the intermediate heat exchanger being in fluid communication with an inlet of the accumulator.

3. The refrigeration system of claim 2, wherein at least a portion of the liquid from the hopper is transported to an inlet of the evaporator by a thermosiphon effect.

4. The refrigeration system of claim 2, wherein the high temperature refrigerant comprises up to about 22% by weight R-32.

5. The refrigeration system of claim 2, wherein the high temperature refrigerant comprises up to about 78% by weight R-1234ze or up to about 78% by weight R-1234 yf.

6. The refrigeration system of claim 2, wherein the high temperature refrigerant comprises from about 10% to about 100% propane by weight.

7. The refrigeration system of claim 2, wherein the condenser operates at a temperature in a range from about 35 ℃ to about 70 ℃.

8. A refrigeration system for cooling air of a space occupied by a human being or for cooling an article located in the space occupied by the human being using the air in the space occupied by the human being, the system comprising:

(a) a high temperature refrigerant circuit comprising:

(i) a high temperature refrigerant flowing through at least a portion of the high pressure circuit to reject heat from the system, wherein at least the portion of the high temperature circuit through which the high temperature refrigerant flows is not located within the space occupied by the human;

(iv) a compressor providing a vapor stream comprising at least a portion of the refrigerant flowing to the condenser;

(v) an intermediate heat exchanger in which at least a portion of the high temperature refrigerant flow from the expansion valve absorbs heat, and from which the intermediate heat exchanger produces a high temperature effluent stream comprising the high temperature refrigerant, the high temperature effluent stream being at a higher temperature than the temperature of the flow from the expansion valve; and

(vi) a suction line heat exchanger connected between the condenser and the expansion valve and between the intermediate heat exchanger and the compressor inlet such that: (1) the suction line heat exchanger receiving at least a portion of the liquid high temperature refrigerant stream from the condenser, wherein heat is rejected from the liquid high temperature refrigerant stream prior to the stream entering the expansion valve; and (2) the suction line heat exchanger receiving at least a portion of the high temperature refrigerant exiting the intermediate heat exchanger and absorbing heat from the liquid high temperature refrigerant stream from the condenser, wherein the stream is in fluid communication with an inlet of the compressor after absorbing the heat;

and

(b) a cryogenic refrigerant circuit comprising:

(i) a cryogenic refrigerant flowing through at least a portion of the low pressure circuit to absorb heat from the space occupied by the human, wherein at least the portion of the cryogenic circuit through which cryogenic refrigerant flows is located within the space occupied by the human, the cryogenic refrigerant comprising at least about 50% by weight of HCFO-1233zd (E) and: (1) non-flammable according to ASHRAE standard 34, (2) has an Occupational Exposure Limit (OEL) of greater than 400 and is classified as class a according to ASHRAE standard 34, and (3) has a GWP of less than about 500;

9. The refrigeration system of claim 8, wherein the high temperature refrigerant comprises one or more of R-32, R-1234ze, R-1234yf, and propane.

10. The refrigeration system of claim 8, wherein the condenser operates at a temperature in a range from about 35 ℃ to about 70 ℃.

11. The refrigeration system of claim 2, further comprising: a sensor for detecting the high temperature refrigerant leaking into the low temperature refrigerant, and a low temperature refrigerant charge controller responsive to the sensor, wherein an additional amount of the low temperature refrigerant is charged into the low temperature refrigeration circuit to ensure that the low temperature refrigerant is maintained as a non-flammable refrigerant.