High efficiency air conditioning systems and methods

Abstract

To provide low capacity air conditioning systems utilizing highly efficient centrifugal compressors and high efficiency evaporators.SOLUTION: A refrigeration system includes a heat source to be cooled and a heat sink into which heat can be rejected, wherein the system has a capacity of from about 2 to about 30 tons and comprises a heat transfer composition comprising a refrigerant including at least about 95 wt.% of trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd) or at least about 80 wt.% of trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze).SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] This application is related to and claims the benefit of priority to U.S. Provisional Application No. 62 / 275,382, filed January 6, 2016, which is incorporated herein by reference in its entirety. The present invention relates generally to air conditioning systems, and more particularly to such systems using centrifugal compressors and having cooling capacities in the range of up to about 30 tons. [Background technology]

[0002] Several halogenated olefins, such as the compounds 1-chloro-3,3,3-trifluoropropene (HFCO-1233zd) and 1,3,3,3-tetrafluoropropene (HFO-1234ze), have been proposed for use in vapor compression refrigeration systems. See US-7,833,433. In the '433 patent, a typical vapor compression system is described as including a compressor for compressing a refrigerant vapor to produce a vapor at a relatively elevated pressure and temperature. An example of such a system is shown herein as Figure P. In such a system, refrigerant is introduced into the suction side of compressor 11 at a relatively low pressure through conduit 19A, and a high pressure refrigerant is discharged and sent to condenser 12 through conduit 19B. Heat is removed from the high temperature refrigerant vapor in condenser 12 by condensing the refrigerant vapor to produce a relatively high pressure liquid refrigerant that is introduced into conduit 15A. The relatively high pressure liquid is then subjected to a virtually isenthalpic pressure drop in expansion device 14 to produce a relatively low temperature, low pressure liquid which is then vaporized in evaporator 24 by heat transferred from the body or fluid being cooled. The resulting low pressure vapor is returned to the suction side of the compressor via conduit 19A, thereby completing the cycle.

[0003] The '433 patent generally suggests that the refrigerant compositions disclosed therein can be used in a variety of different cooling operations using vapor compression systems, including chiller systems using centrifugal compressors. Typically, centrifugal chillers are large capacity systems, i.e., systems having capacities greater than 50 tons. Most commonly, such systems are in the range of 50 to 150 tons of cooling capacity, with some systems going as high as 8,500 tons. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US-7,833,433 Summary of the Invention [Problem to be solved by the invention]

[0005] Applicants have come to recognize that several unexpected problems exist with respect to attempting to use trans-HFCO-1233zd and / or trans-HFO-1234ze in low capacity air conditioning systems that employ highly efficient centrifugal compressors. As described in detail below, Applicants have unexpectedly discovered that these problems can be overcome while simultaneously overcoming the problems Applicants have recognized with respect to using trans-HFCO-1233zd and / or trans-HFO-1234ze in such systems by employing one or more special configurations in the air conditioning system that allow for the use of highly efficient equipment, including highly efficient compressors and evaporators. [Means for solving the problem]

[0006] Applicants have developed a low capacity air conditioning system that uses a highly efficient centrifugal compressor and a highly efficient evaporator. Applicants have come to recognize that in many applications it is highly desirable to provide a refrigerant composition that provides a high proportion (e.g., greater than about 80% by weight) of HCFO-1233zd(E) or a high proportion (e.g., greater than about 80% by weight) of HFO-1234ze(E) can present significant problems with respect to the reliability and / or effectiveness and / or efficiency of such systems.

[0007] For example, in some air conditioning systems, it is highly desirable to use flooded evaporators, since such heat exchange devices provide highly efficient heat transfer to the liquid refrigerant. This highly efficient operation is due, at least in part, to the fact that in such devices the heat transfer surfaces are substantially fully covered by the liquid refrigerant. However, as a result of using such highly efficient devices, the vapor discharged from such evaporators is substantially saturated, i.e., has little or no superheat. While this is advantageous from an efficiency standpoint, it becomes particularly important in such situations to ensure that the vapor introduced to the compressor at or near saturation does not condense, since the presence of such liquid refrigerant in the compressor would have negative consequences on the efficiency and / or reliability of the compressor operation. Since during the apparent isentropic expansion that occurs in a highly efficient compressor, heat is added to the refrigerant vapor to produce a superheat of at least about 5° C. at the compressor discharge, the use of saturated or near saturation refrigerant vapor at the compressor suction does not present a problem under normal operating conditions with other refrigerants.

[0008] However, the applicants have come to realize that problems arise when using the preferred refrigerant compositions of the present invention in systems using highly efficient centrifugal compressors under the conditions of the type preferred in the present invention. More specifically, the applicants have found that the preferred refrigerant compositions of the present invention do not generate the usual or expected amount of superheat during highly efficient compression under normal conditions. In fact, the applicants have found that in the absence of one or more solutions provided in the present invention for the operation of highly efficient centrifugal compressors, "wet vapor" is discharged from the compressor. The term "wet vapor" as used herein refers to vapor that has condensate entrained therein. As is well known to those skilled in the art, the presence of such vapor in a compressor can be very detrimental to the efficient and / or reliable operation of a centrifugal compressor. Thus, the applicants have found that the use of the refrigerants according to the preferred forms of the present invention can create unexpected problems in the operation of highly efficient centrifugal compressors in the absence of the present solutions, especially in applications that also use highly efficient low or no superheat evaporators. However, applicants have also come to realize that operating such systems with the preferred heat transfer compositions of the present invention is highly desirable as it can provide advantageous and environmentally friendly operation.

[0009] To overcome the problems and difficulties which applicants have come to recognize, one aspect of the present invention provides a cooling system of the type having a heat source to be cooled and a heat sink capable of rejecting heat therein, comprising: Preferably, it has a capacity of about 2 to about 30 tons, (a) a heat transfer composition comprising a refrigerant comprising at least about 80% by weight of trans-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)), or at least about 80% by weight of trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)); (b) (i) a refrigerant suction for receiving a relatively low pressure refrigerant vapor having a pressure of about 40 to about 350 kPa; and (ii) a relatively high pressure refrigerant vapor having a predetermined pressure. and a discharge:inlet pressure ratio of at least about 2. :1 centrifugal compressor; (c) receiving at least a portion of the compressor discharge refrigerant vapor and condensing at least a substantial portion of the refrigerant vapor, preferably substantially all of the refrigerant vapor, by heat transfer with the heat sink; a condenser fluidly connected to the refrigerant discharge outlet of the compressor for producing a relatively high pressure refrigerant liquid having a temperature in the range of about 10° C. to about 60° C.; (d) an expansion device fluidly connected to the condenser for substantially isenthalpic reduction in pressure of the high pressure refrigerant liquid to produce a low pressure refrigerant liquid at a pressure of about 40 to about 350 kPa; (e) a high efficiency evaporator, preferably a flooded evaporator, fluidly connected to the expander for receiving the low pressure refrigerant liquid from the expander and evaporating the low pressure refrigerant liquid by absorbing heat from a heat source to be cooled to produce a relatively low pressure refrigerant vapor at a pressure of about 40 to about 350 kPa (the refrigerant vapor discharged from the evaporator preferably has substantially no superheat); (f) at least one heat exchanger fluidly connected between the evaporator and the compressor refrigerant suction for receiving at least a portion of the low pressure refrigerant vapor from the evaporator and heating the low pressure refrigerant vapor to produce a low pressure refrigerant vapor having a temperature at least about 5° C. higher than a temperature of the vapor introduced into the at least one heat exchanger (the high temperature refrigerant vapor from the at least one heat exchanger is fluidly connected to the compressor suction for supplying the low pressure refrigerant vapor to the compressor); The cooling system includes:

[0010] As used herein, the term "capacity" defined in numerical units of "tons" refers to a heat transfer rate equal to the amount of heat required to melt one ton (2000 pounds; 907 kg) of 0° C. (32° F.) ice in 24 hours, generally equal to about 12,000 BTU / hour.

[0011] Other aspects and embodiments of the present invention are disclosed below. [Brief description of the drawings]

[0012] [Figure 1A] Figure P is a diagram of a prior art heat transfer system. [Figure 1B] FIG. 1 is a generalized process flow diagram of one preferred embodiment of an air conditioning system according to the present invention. [Diagram 2] FIG. 2 is a generalized process flow diagram of another preferred embodiment of an air conditioning system according to the present invention. [Diagram 3] FIG. 3 is a generalized process flow diagram of another preferred embodiment of an air conditioning system according to the present invention. [Figure 4A] FIG. 4A is a generalized process flow diagram of another preferred embodiment of an air conditioning system according to the present invention. [Figure 4B] FIG. 4B is a more specific process flow diagram of a preferred embodiment of an air conditioning system having a combustion suppression mechanism according to one aspect of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Preferred heat transfer compositions: In each of the embodiments described herein, the system includes a heat transfer composition including a refrigerant and preferably (but not necessarily) a lubricant for the compressor. Preferably, the refrigerant is a low flammability and low toxicity refrigerant including at least about 70% by weight, or at least about 80% by weight, of trans-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)) or trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), preferably having a Class A toxicity according to ASHRAE Standard 2013 and a Class 1 or Class 2 or Class 2L flammability according to ASHRAE Standard 34-2013 and as set forth in Appendix B1 to ASHRAE Standard 34-2013.

[0014] In highly preferred embodiments, such as embodiments of the type disclosed herein that include systems and methods that provide a combustion suppression mechanism, the refrigerant comprises at least about 95% by weight HFCO-1233zd(E), and in some embodiments consists essentially of or consists of at least about 95% by weight HFCO-1233zd(E). , or consisting of

[0015] In another highly preferred embodiment, the refrigerant comprises from about 1% to about 5% by weight of a five-carbon saturated hydrocarbon, preferably one or more of isopentane, n-pentane, or neopentane, and in a preferred form of such embodiment, the combination of HFCO-1233zd(E) and pentane is in the form of an azeotropic composition. Such azeotrope and azeotrope-like compositions are disclosed in U.S. Patent No. 8,802,874, U.S. Patent No. 8,163,196, and U.S. Patent No. 8,703,006, each of which is incorporated herein by reference. The heat transfer compositions of the present invention, including the refrigerant compositions described in this paragraph, preferably include a lubricant comprising or consisting of POE and / or mineral oil and / or alkylbenzene.

[0016] In highly preferred embodiments, such as those of the type disclosed herein including those that provide systems and methods with a burn suppression mechanism, the refrigerant comprises about 85% to about 90% by weight of trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and about 10% to about 15% by weight of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), and even more preferably in some embodiments about 88% trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and about 12% by weight of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). The heat transfer compositions of the present invention, including the refrigerant compositions described in this paragraph, preferably include a lubricant that comprises or consists of POE.

[0017] Those skilled in the art will appreciate, in light of the disclosure contained herein, that certain embodiments of the present invention provide the advantage of using only refrigerants that are relatively safe (low toxicity and low flammability) and have low GWP (which makes them highly desirable for use in close proximity to humans or other animals occupying occupied rooms typically encountered in air conditioning applications).

[0018] The heat transfer composition of the present invention generally includes a lubricant. However, embodiments of the present invention encompass systems and methods using compressors that do not require a lubricant and / or that do not require a lubricant to be combined with the refrigerant. However, for preferred embodiments in which the lubricant and refrigerant are included together as a mixture at one or more locations in the system, the lubricant is preferably present in the system in an amount of about 30 to about 50% by weight of the heat transfer composition based on the total weight of the refrigerant in the system and the total weight of the lubricant in the system, and optionally other optional ingredients as described below. In preferred embodiments, the heat transfer composition of the present invention, particularly as introduced to the evaporator in the form of carryover vapor from the compressor and liquid from the condenser, includes about 97% to about 99.5% by weight of the refrigerant of the present invention, and about 0.5 to about 3% by weight of the lubricant, which is preferably a POE lubricant and / or a mineral oil lubricant.

[0019] Other optional ingredients include compatibilizers such as propane to promote compatibility and / or solubility of the lubricant. When present, such compatibilizers, such as propane, butanes, and pentanes, are preferably present in an amount of about 0.5 to about 5% by weight of the composition. A combination of surfactants and compatibilizers may also be added to the composition to promote oil solubility, as disclosed by U.S. Patent 6,516,837, the disclosure of which is incorporated herein by reference. Commonly used refrigeration lubricants such as polyol esters (POE) and polyalkylene glycols (PAG), silicone oils, mineral oils, alkylbenzenes (AB), and poly(α-olefins) (PAO) used in chillers with hydrofluorocarbon (HFC) refrigerants may be used with the refrigerant compositions of the present invention. Preferred lubricants of the present invention are selected from POE and mineral oil and alkylbenzenes.

[0020] system: The present cooling systems and methods are particularly well suited for use in low capacity air conditioning systems, i.e., systems having a capacity of 30 tons or less, particularly residential air conditioning systems, especially residential air conditioning systems having a capacity of from about 2 to about 5 tons, and commercial packaged rooftop air conditioning units, especially having a capacity of from about 5 to about 30 tons.

[0021] An embodiment of the type shown in FIG. A preferred air conditioning system, generally designated 10, is shown in FIG. 1. Such a preferred air conditioning system includes a compressor 11, a condenser 12, an evaporator 24 (preferably a flooded evaporator), an expansion valve 14, and a suction line heat exchanger 30, along with any associated conduits 15A, 15B, 16A, and 16B, and other connections and associated equipment (not shown). In operation, a refrigerant according to the present invention is discharged from the compressor 11 as a relatively high pressure refrigerant vapor, which may include entrained lubricant, which is then passed through conduit 19C to the condenser 12. In the condenser 12, the refrigerant vapor transfers a portion of its heat, preferably by phase change, preferably to ambient air to produce an output stream comprising at least partially, preferably substantially completely, condensed refrigerant. The refrigerant output stream from the condenser 12 is passed through conduit 15A to the suction line heat exchanger 30 where it picks up additional heat with the output stream from the evaporator 24, as described more fully below. The output from suction / liquid line heat exchanger 30 is then sent via conduit 15B to expansion valve 14 where the pressure of the refrigerant is reduced, preferably substantially isenthalpic, thereby reducing the temperature of the refrigerant. The relatively cool liquid refrigerant from expansion valve 14 flows into receiver tank 18, which provides a reservoir of cool liquid refrigerant, which is fed via a control valve (not shown) in conduit 19A into evaporator 24 where it absorbs heat from an object or fluid being cooled, preferably the ambient air within the room or other space being cooled. The refrigerant output vapor from evaporator 24, which is preferably substantially saturated refrigerant vapor with no substantial superheat (e.g., the vapor exiting the evaporator has a superheat of less than about 1° C., more preferably less than about 0.5° C., and even more preferably less than about 0.1° C.), is then sent via conduit 19A to suction / liquid line heat exchanger 30 where it obtains heat from the condenser output from conduit 15A to produce hotter refrigerant vapor which is sent by conduit 16B to the inlet of compressor 11. In a preferred embodiment, the vapor exiting the suction line heat exchanger has a temperature at least about 5° C. higher than the substantially saturated vapor entering the suction line heat exchanger, and even more preferably at least about 7° C. The hot refrigerant vapor is then passed to the suction of compressor 11 where it is compressed as described above.

[0022] In a preferred embodiment in which the refrigerant comprises, and preferably consists essentially of, at least about 90% by weight HCFO-1233zd(E), the operating conditions correspond to the values ​​set forth in the table below.

[0023] [Table 1]

[0024] The refrigerant is at least about 80% by weight HFO-1234ze(E), and even more preferably 8 In a preferred embodiment containing 8 wt. % HFO-1234ze(E) and 12 wt. % HFC-227ea, the operating conditions correspond to the values ​​set forth in the table below.

[0025] [Table 2]

[0026] An embodiment of the type shown in FIG. A further preferred air conditioning system, generally designated 10, is shown in Figure 2. Such a preferred air conditioning system includes a multi-stage compressor, shown as a two-stage compressor 11, a condenser 12, an evaporator 24 (preferably a flooded evaporator in some embodiments), an expansion valve 14, and a vapor injection heat exchanger 40 including an associated intermediate expansion valve 41, along with any associated conduits 15A-15C and 19A-19D, and other connections and associated equipment (not shown and / or not depicted). In operation, a refrigerant according to the present invention is discharged from the compressor 11 as a relatively high pressure refrigerant vapor, which may include entrained lubricant, which is then passed through conduit 19D to the condenser 12. In the condenser 12, the refrigerant vapor transfers a portion of its heat, preferably by phase change, preferably to ambient air to produce an outlet stream including at least partially, preferably substantially completely, condensed refrigerant. The refrigerant output stream from condenser 12 is directed through conduit 15A, a portion of the refrigerant output stream is directed through conduit 15B to intermediate expansion device 41, and another portion of the output stream, preferably the remainder of the output stream, is directed to steam injection heat exchanger 40.

[0027] In operation, the intermediate expansion device 41 reduces the pressure of the exiting stream, preferably substantially isenthalpic, to about the pressure of the second stage inlet of compressor 11 or to a pressure sufficiently higher than accounting for the pressure drop through heat exchanger 41 and associated conduits, fittings, etc. As a result of the pressure drop across the expansion device 41, the temperature of the refrigerant entering heat exchanger 40 is reduced relative to the temperature of the high pressure refrigerant entering heat exchanger 40. Within heat exchanger 40, heat is transferred from the high pressure stream to the stream that has passed through expansion valve 41. As a result, the temperature of the intermediate pressure stream exiting heat exchanger 40 is preferably at least about 5° C. higher than the temperature of the inlet stream, thereby producing a superheated vapor stream that is passed to the second stage of compressor 11 via conduit 19C.

[0028] As the higher pressure stream delivered by conduit 15A is delivered through heat exchanger 40, it picks up heat against the lower pressure stream discharged from expansion device 41, exits the heat exchanger via conduit 15C and then enters receiver tank 18 which provides a reservoir of cold liquid refrigerant which is delivered into evaporator 24 via a control valve (not shown) in conduit 19A. The ambient air to be cooled picks up heat against the cold liquid refrigerant in the evaporator, causing the liquid refrigerant to vaporize and produce a refrigerant vapor with little or no superheat which is then delivered to the first stage of compressor 11.

[0029] In a preferred embodiment in which the refrigerant comprises, and preferably consists essentially of, at least about 90% by weight HCFO-1233zd(E), the operating conditions correspond to the values ​​set forth in the table below.

[0030] [Table 3]

[0031] In a preferred embodiment in which the refrigerant comprises at least about 80 wt.% HFO-1234ze(E), even more preferably 88 wt.% HFO-1234ze(E) and 12 wt.% HFC-227ea, the operating conditions correspond to the values ​​set forth in the table below.

[0032] [Table 4]

[0033] An embodiment of the type shown in FIG. A further preferred air conditioning system, generally designated 10, is shown in FIG. 3. Such a preferred air conditioning system includes a compressor 11, which may be a multi-stage compressor of the type described herein, but which in the illustrated embodiment is shown as a single stage compressor, a condenser 12, an evaporator 24 (preferably a flooded evaporator in some embodiments), an expansion valve 14, a flash gas separator 18, along with any associated conduits 15A-15C and 19A-19C, and other connections and associated equipment (not shown and / or not depicted). In operation, a refrigerant according to the present invention is discharged from the compressor 11 as a relatively high pressure refrigerant vapor, which may include entrained lubricant, which is then passed through conduit 19C to the condenser 12. In the condenser 12, the refrigerant vapor transfers a portion of its heat, preferably by phase change, preferably to the surrounding ambient air to produce an output stream comprising at least partially, preferably substantially completely, condensed refrigerant. The refrigerant output stream from the condenser 12 is passed through conduit 15A to the expansion device 14. The lower pressure stream discharged from the expander 14 flows through conduit 15B to a flash gas separator 18 which provides a reservoir of cold liquid refrigerant which is fed to the evaporator 24 via a control valve (not shown) in conduit 15C. The ambient air to be cooled is absorbed by the cold liquid refrigerant in the evaporator 24, causing the liquid refrigerant to vaporize and produce a refrigerant vapor with little or no superheat which is then passed to the first stage of the compressor 11. The flash gas produced during the pressure drop in the expansion device 14 is then passed to the suction side of the compressor 11 through conduit 19B.

[0034] The refrigerant comprises at least about 90% by weight HCFO-1233zd(E), preferably In a preferred embodiment consisting essentially of, and preferably consisting of, the operating conditions correspond to the values ​​set out in the table below.

[0035] [Table 5]

[0036] In a preferred embodiment in which the refrigerant comprises at least about 80 wt.% HFO-1234ze(E), even more preferably 88 wt.% HFO-1234ze(E) and 12 wt.% HFC-227ea, the operating conditions correspond to the values ​​set forth in the table below.

[0037] [Table 6]

[0038] An embodiment of the type shown in FIG. A further preferred air conditioning system, generally designated 10, is shown in FIG. 4A. Such preferred air conditioning system includes a compressor 11, which may be a multi-stage compressor of the type described herein, a condenser 12, an evaporator 24 (preferably a flooded evaporator in some embodiments), an expansion valve 14, a high pressure receiver, along with any associated conduits 15A-15C and 19A-19B, and other connections and associated equipment (not shown and / or labeled). In operation, a refrigerant according to the present invention is discharged from the compressor 11 as a relatively high pressure refrigerant vapor, which may include entrained lubricant, which is then passed through conduit 19B to the condenser 12. In the condenser 12, the refrigerant vapor transfers a portion of its heat, preferably by phase change, preferably to the surrounding ambient air to produce an output stream comprising at least partially, preferably substantially completely, condensed refrigerant. The refrigerant output stream from the condenser 12 is passed through conduit 15A to the high pressure receiver 50, which provides a reservoir of liquid refrigerant. A sensor activated safety valve 60 is connected to conduit 15A via a port or other form of connection. The sensor activated safety valve includes and / or is in communication with a sensor that monitors for flames, smoke, flammable gas concentrations, or other indications that a flame is present or likely to occur, and such sensor is located near some portion of the refrigeration system, preferably within the occupant or other area being cooled. Because the preferred refrigerants of the present invention have flammability suppressing properties, if the sensor detects flame and / or smoke (or other indications that a possible or increased likelihood of fire exists), the sensor activated safety valve opens and releases refrigerant into the area in which it is located to prevent the refrigerant from entering the refrigerant. This helps to suppress and / or eliminate the fire. The use of a high pressure receiver ensures that a relatively large reservoir of high pressure liquid refrigerant is available in the event of such an emergency. The remainder of the refrigeration system can operate according to any one or more of the embodiments described herein. EXAMPLES

[0039] Example 1: 1233zd without suction line heat exchanger: In an air conditioning system according to the representative configuration shown in the drawing labeled Prior Art, a refrigerant consisting of HCFO-1233zd(E) was used according to the following parameters:

[0040] Operating conditions: 1. Evaporation temperature: 7℃; 2. Condensation temperature: Varies from 20℃ to 60℃; 3. Isentropic efficiency: varies from 0.7 to 0.8; 4. No overcooling or overheating.

[0041] Since the present system has no superheat in the vapor exiting the evaporator (as would be the case, for example, with a flooded evaporator), saturated vapor is introduced to the suction side of the centrifugal compressor. In normal operation with many other refrigerants, isentropic or near isentropic expansion of the refrigerant vapor produces a discharge gas with a temperature at discharge pressure that indicates at least about 5° C. of superheat. This degree of superheat is generally considered necessary to ensure safe and reliable operation of the compressor to ensure that no “wet vapor” is present in the compressor. For the present system, operation at several levels of near isentropic compression was evaluated to determine whether safe and reliable operation could be achieved with HCFO-1233zd(E). The results are reported in Table 1 below.

[0042] [Table 7]

[0043] As can be seen from the results reported in Table 1 above, when using the most efficient compressor (isentropic efficiency = 1), at least some of the steam exiting the compressor is This results in a wet vapor discharge stream containing liquid in the condenser, which, as noted above, has a significant negative impact on efficient and / or reliable operation. When the compressor efficiency was reduced to 0.8, the desired level of superheat was still not achieved for any of the condenser temperatures tested. Even when the compressor efficiency was reduced to 0.75 and 0.7 (not a preferred option in itself), the desired level of superheat was not achieved for the full range of condenser temperature conditions.

[0044] Example 2A: 1233zd with suction line heat exchanger: Using a suction line heat exchanger (SLHX) as shown in Figure 1 and using a refrigerant consisting of HCFO-1233zd(E), an air conditioning system according to the arrangement according to the invention was tested with a single stage compressor operating at 80% isentropic efficiency according to the same operating parameters as in Example 1. Several levels of heat exchanger efficiency for the suction line heat exchanger were investigated and the results are reported below in Table 2A.

[0045] [Table 8]

[0046] As can be seen from the results reported above, operation according to the embodiment of the invention as shown in FIG. 1 produced a superheat of at least about 5° C. at the compressor discharge for the entire range of condensing temperatures tested.

[0047] Example 2B: Azeotrope with R1233zd: Example 2A was repeated, except that the refrigerant consisting solely of 1233zd(E) used in Example 2A was replaced with a series of azeotropic refrigerant blends based on HCFO-1233zd(E), as set forth in Table 2B below. Acceptable operation was achieved.

[0048] Additionally, the transport properties of these additional refrigerants were tested along with the properties of a refrigerant comprised of HCFO-1233zd(E) and are reported below in Table 2B.

[0049] [Table 9]

[0050] Example 3A: 1233zd with suction line heat exchanger: An air conditioning system according to the present invention as shown in Figure 1 was tested using a suction line heat exchanger (SLHX) having SLHX efficiencies of 0.5 and 0.7, with a refrigerant consisting of HCFO-1233zd(E), following the same operating parameters as in Example 1. The testing provides a comparison of the relative effectiveness of such a system with the system described in Example 1 without the SLHX (both systems using 80% compressor efficiency), and is reported below in Table 3A.

[0051] [Table 10]

[0052] As can be seen from the results reported above in Table 3A, in addition to overcoming the wet steam problem, a system according to the configuration of FIG. 1 provided improved overall system efficiency (COP) for all conditions tested.

[0053] Example 4A: 1233zd with multi-stage compressor: An air conditioning system according to the present invention using a two-stage compressor according to the system configuration shown in FIG. A series of condensing temperatures ranging from 30° C. to 60° C. was tested using a refrigerant consisting of HCFO-1233zd(E). For each of these condenser temperatures, the operating conditions for the compressor at 80% isentropic efficiency and an evaporator temperature of 7° C. are reported in Table 4A1.

[0054] [Table 11]

[0055] The same air conditioner as shown in Figure 2 using a multi-stage compressor arrangement was tested with a refrigerant consisting of HCFO-1233zd(E) and compared to operation with a single stage compressor according to the configuration in Example 1. Additionally, the same set of comparative tests were performed with a refrigerant consisting of R11. The results of these comparative tests are reported below in Table 4A2.

[0056] [Table 12]

[0057] As can be seen from the results reported above, dramatic improvements in system efficiency (COP) were observed using the configuration of the present invention, with improvements of up to 115% observed as a result of using two and three stage compression according to embodiments of the type shown in Figure 2. Furthermore, the test results reported above show that the use of HCFO-1233zd(E) in both two and three stage compressor operation resulted in substantially better improvements in efficiency (COP) compared to the improvements observed in the same system but using R-11.

[0058] Example 5: 1233zd and 1233zd Blends Using Flash Gas Separator: Using the flash gas separator shown in FIG. 3 and using a refrigerant consisting of HCFO-1233zd(E) and the blends specified in Table 5 below, an air conditioning system according to the arrangement according to the invention was operated at 80% isentropic pressure according to the same operating parameters as in Example 1. The system was tested with a single stage compressor operating at maximum efficiency. The evaporator was operated in flooded configuration, providing a reduced pressure drop across the evaporator, which provided a higher suction pressure at the compressor. Additionally, because the pressure in the system is relatively low as a result of using a refrigerant comprised of HCFO-1233zd(E) and the blends in Table 5, compact heat exchangers made of low-cost materials can be used. For example, round tube / fin and / or microchannel heat exchangers can be made of aluminum instead of copper. This configuration provides a low weight, compact heat exchange system with excellent heat exchange performance.

[0059] Example 6: 1233zd(E) and Blends of 1233zd(E) with Sensor Activated Safety Valve: An air conditioning system according to the arrangement of the present invention was tested using the sensor-activated safety valve shown in Figures 4A and 4B with a refrigerant consisting of HCFO-1233zd(E) and each of the refrigerants disclosed in Table 2B. The sensor-activated safety valve is preferably a solenoid type valve. The sensor used measures the natural gas concentration in a home heating unit. In the event of a fuel leak, such as a natural gas leak in the burner mechanism of the heating unit, the sensor detects an elevated gas concentration, such as 1000 ppm, and activates the solenoid valve. The activated valve opens and releases R1233zd(E) into the flammable natural gas atmosphere. Due to the fire suppression properties of R1233zd(E), the possibility of a fire is reduced by suppressing and / or eliminating a fire condition in the vicinity of the safety valve located in close proximity to the sensed flammable atmosphere. Thus, a fire condition or a condition indicative of an increased likelihood of fire is detected by the sensor and the safety valve is opened to suppress and / or eliminate the fire condition proximate the sensed flame and / or the safety valve is located proximate to the sensed condition.

[0060] Example 7A: 1234ze(E) Blend without Inlet Line Heat Exchanger: In an air conditioning system following the representative configuration shown in the drawings labeled Prior Art, a refrigerant composed of about 88% by weight HFO-1234ze(E) and about 12% by weight R227ea was used according to the following parameters:

[0061] Operating conditions - conventional technology: 1. Evaporation temperature: 7℃; 2. Condensation temperature: Varies from 20℃ to 60℃; 3. Isentropic efficiency: 0.7~0.8; 4. No overcooling or overheating.

[0062] Since the present system has no superheat in the vapor exiting the evaporator (as would be the case, for example, with a flooded evaporator), saturated vapor is introduced to the suction side of the centrifugal compressor. In normal operation with many other refrigerants, isentropic or near isentropic expansion of the refrigerant vapor produces a discharge gas with a temperature at discharge pressure that indicates at least about 5° C. of superheat. This degree of superheat is generally considered necessary to ensure safe and reliable operation of the compressor to ensure that no “wet vapor” is present in the compressor. For the present system, operation at several levels of near isentropic compression was evaluated to determine whether safe and reliable operation could be achieved with the blends of HFO-1234ze(E) and R-227ea described above. The results are reported below in Table 7A.

[0063] [Table 13]

[0064] As can be seen from the results reported in Table 7A above, all but five of the conditions tested did not produce the minimum level of superheat of 5° C. at the compressor discharge, and the condition that produced more superheat than this minimum was one that employed an undesirably low isentropic efficiency of 0.7 at high condenser temperatures.

[0065] Example 7B: 1234ze Blend with Suction Line Heat Exchanger: Using a suction line heat exchanger (SLHX) as shown in Figure 1, and using a refrigerant composed of about 88% by weight HFO-1234ze(E) and about 12% by weight R227ea, an air conditioning system according to the arrangement of the present invention was tested with a single stage compressor operating at 80% isentropic efficiency according to the same operating parameters as in Example 7. Several levels of heat exchanger efficiency for the suction line heat exchanger were investigated and the results are reported below in Table 7B.

[0066] [Table 14]

[0067] As can be seen from the results reported in Table 7B above, operation according to the embodiment of the invention as shown in FIG. 1 produced a superheat of at least about 5° C. at the compressor discharge for the entire range of condensing temperatures tested.

[0068] Example 7C: 1234ze Blend with Suction Line Heat Exchanger: An air conditioning system according to the present invention as shown in Figure 1 was tested using a suction line heat exchanger (SLHX) having SLHX efficiencies of 0.5 and 0.7, with a refrigerant consisting of about 88% HFO-1234ze(E) and about 12% R227ea by weight, according to the same operating parameters as in Example 7A. The testing provides a comparison of the relative effectiveness of such a system with the system described in Example 7A without the SLHX (both systems using a compressor efficiency of 80%), and is reported below in Table 7C.

[0069] [Table 15]

[0070] As can be seen from the results reported above in Table 7C, in addition to overcoming the wet steam problem, the system according to the configuration of FIG. 1 provided an improvement in overall system efficiency (COP) for all conditions tested.

[0071] Example 8A: 1234ze Blend Using Multi-Stage Compressor: Air conditioning systems according to the present invention were tested using two-stage and three-stage compressors according to the system configuration shown in Figure 2, using a refrigerant composed of about 88% by weight HFO-1234ze(E) and about 12% by weight R227ea, and compared to operation of a single-stage compressor operated according to the configuration in Example 1. Additionally, the same set of comparative tests were performed with a refrigerant composed of R134a. The results of these comparative tests are reported below in Table 8A.

[0072] [Table 16]

[0073] As can be seen from the results reported above, using the configuration of the present invention according to the type of embodiment shown in Figure 2, dramatic improvements in system efficiency (COP) were observed as a result of using two and three stage compression in amounts up to 115%. Furthermore, the test results reported above show that using HFO-1234ze(E) / 227ea blends in both two and three stage compressor operation resulted in substantially better improvements in efficiency (COP) compared to the improvements observed in the same system but using R134a.

[0074] Example 9: In each of the above examples, the system includes plastic parts that come into contact with the refrigerant during operation. The materials from which these parts are manufactured are compatible and / or stable. Applicants have tested the stability of various plastic materials when exposed to trans-HFCO-1233zd. The testing involved immersing samples of various plastics in trans-HFCO-1233zd at room temperature (approximately 24° C. to 25° C.) under ambient pressure conditions for two weeks, after which the samples were removed from trans-HFCO-1233zd and allowed to degas for 24 hours. The results are reported in Table 9 below.

[0075] [Table 17]

[0076] As shown by the results in Table 5 above, the average % volume change for each of the plastic materials tested was less than 5%.

Claims

1. 1. A cooling system of the type having a heat source to be cooled and a heat sink capable of rejecting heat therein, It has a capacity of about 2 to about 30 tons, (a) a heat transfer composition comprising a refrigerant comprising at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd), or at least about 80% by weight trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze); (b) a centrifugal compressor having a refrigerant inlet for receiving a low pressure refrigerant vapor at a pressure of about 45 to about 75 kPa and a discharge for discharging a high pressure refrigerant vapor at a pressure of about 100 to about 520 kPa, the compressor having an efficiency of at least about 0.65; (c) a condenser fluidly connected to the refrigerant discharge of the compressor for receiving the high pressure refrigerant vapor and for condensing at least a substantial portion of the refrigerant vapor by heat transfer through the heat sink to produce a high pressure refrigerant liquid at a temperature in the range of about 10° C. to about 60° C.; (d) an expansion device fluidly connected to the condenser for substantially isenthalpic reduction in pressure of the high pressure refrigerant liquid to produce a low pressure refrigerant liquid at a pressure of about 45 to about 75 kPa; (e) an evaporator fluidly connected to the expander for receiving a low pressure refrigerant liquid and evaporating the low pressure refrigerant liquid by absorbing heat from a heat source to be cooled to produce a low pressure refrigerant vapor at a pressure of about 45 to about 75 kPa; and (f) at least one heat exchanger fluidly connected between the evaporator and the compressor suction for receiving at least a portion of the low pressure refrigerant vapor from the evaporator and heating the low pressure refrigerant vapor to produce a low pressure refrigerant vapor having a temperature at least about 5° C. higher than a temperature of the vapor introduced into the at least one heat exchanger, the high temperature refrigerant vapor from the at least one heat exchanger being fluidly connected to the compressor suction for supplying the low pressure refrigerant vapor to the compressor; Cooling system including:

2. 10. The refrigeration system of claim 1, wherein the refrigerant comprises at least about 80% by weight trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze).

3. 2. The refrigeration system of claim 1, wherein the refrigerant comprises at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd).

4. 1. A cooling system of the type having a heat source to be cooled and a heat sink capable of rejecting heat therein, It has a capacity of about 2 to about 30 tons, (a) a heat transfer composition comprising a refrigerant comprising at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd), or at least about 70% by weight trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze); (b) a centrifugal compressor having a first stage and at least a second stage, each such stage having a refrigerant inlet for receiving a relatively low pressure refrigerant vapor at a pressure of about 45 to about 75 kPa, and a refrigerant discharge for discharging a relatively higher pressure refrigerant vapor at a pressure of about 100 to about 520 kPa, and having an efficiency of at least about 0.65; (c) a condenser fluidly connected to the refrigerant discharge of at least the second stage of the compressor for receiving high pressure refrigerant vapor from the at least second stage and for condensing at least a substantial portion of the refrigerant vapor by heat transfer through a heat sink to produce a high pressure refrigerant liquid at a temperature in the range of about 10° C. to about 60° C.; (d) a refrigerant coolant supply means for reducing the pressure of at least a first portion of the high pressure refrigerant liquid substantially isoenthalpically to produce a first low pressure refrigerant liquid at a pressure of about 45 to about 75 kPa; at least a first inflator connected to the (e) at least a second expander fluidly connected to the condenser for substantially isenthalpic reduction in pressure of at least a second portion of the high pressure refrigerant liquid to produce a second low pressure refrigerant liquid at a pressure of about 100 to about 520 kPa; (f) an evaporator fluidly connected to at least the first expander for receiving the first low pressure refrigerant liquid and evaporating the low pressure refrigerant liquid by absorbing heat from a heat source to be cooled to generate a low pressure refrigerant vapor at a pressure of about 100 to about 520 kPa, with at least a portion of the refrigerant vapor from the evaporator fluidly connected to the first stage compressor suction; and (g) at least one heat exchanger and / or at least one flash tank fluidly connected between the second expander and at least the second stage suction for receiving at least a portion of the second low pressure refrigerant liquid and discharging therefrom a refrigerant vapor at approximately the pressure of the second low pressure refrigerant liquid, the refrigerant vapor at approximately the pressure of the second low pressure refrigerant liquid being fluidly connected to the second stage compressor suction.

5. 5. The refrigeration system of claim 4, wherein the refrigerant comprises at least about 80% by weight trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze).

6. 5. The refrigeration system of claim 4, wherein the refrigerant comprises at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd).

7. 1. A cooling system of the type having a heat source to be cooled and a heat sink capable of rejecting heat therein, It has a capacity of about 2 to about 5 tons, (a) a heat transfer composition comprising a refrigerant comprising at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd), or at least about 80% by weight trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze); (b) a centrifugal compressor having a refrigerant inlet for receiving a relatively low pressure refrigerant vapor at a pressure of about 45 to about 75 kPa and a refrigerant discharge for discharging a relatively higher pressure refrigerant vapor at a pressure of about 100 to about 520 kPa, the compressor having an efficiency of at least about 0.65; (c) a condenser fluidly connected to the refrigerant discharge of the compressor for receiving high pressure refrigerant vapor from the compressor and condensing at least a substantial portion of the refrigerant vapor by heat transfer through a heat sink to produce a high pressure refrigerant liquid at a temperature in the range of about 45 to about 75 kPa; (d) at least a first expander fluidly connected to the condenser for substantially isenthalpic reduction in pressure of at least a first portion of the high pressure refrigerant liquid to produce a first low pressure refrigerant liquid at a pressure of about 45 to about 75 kPa; (e) an evaporator fluidly connected to at least the first expander for receiving a low pressure refrigerant liquid and evaporating at least a portion of the low pressure refrigerant liquid by absorbing heat from a heat source to be cooled to generate a low pressure refrigerant vapor at a pressure of about 45 to about 75 kPa, at least a portion of the refrigerant vapor from the evaporator being fluidly connected to the compressor suction, and at least one of the condenser and the evaporator being formed essentially from aluminum; Cooling system including:

8. 8. The refrigeration system of claim 7, wherein the refrigerant comprises at least about 80% by weight trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze).

9. 8. The refrigeration system of claim 7, wherein the refrigerant comprises at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd).

10. A type that has a heat source to be cooled and a heat sink that can block heat therein A cooling system comprising: It has a capacity of about 2 to about 30 tons, (a) a heat transfer composition comprising a refrigerant comprising at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd), or at least about 80% by weight trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze); (b) a centrifugal compressor having a refrigerant inlet for receiving a relatively low pressure refrigerant vapor at a pressure of about 45 to about 75 kPa and a refrigerant discharge for discharging a relatively higher pressure refrigerant vapor at a pressure of about 100 kPa to about 520 kPa, the compressor having an efficiency of at least about 0.65; (c) a condenser fluidly connected to the refrigerant discharge of the compressor for receiving high pressure refrigerant vapor from the compressor and condensing at least a substantial portion of the refrigerant vapor by heat transfer through a heat sink to produce a high pressure refrigerant liquid at a temperature in the range of about 10° C. to about 60° C.; (d) at least a first expander fluidly connected to the condenser for substantially isenthalpic reduction in pressure of at least a first portion of the high pressure refrigerant liquid to produce a low pressure stream comprising a combination of refrigerant liquid and refrigerant vapor at a pressure of about 45 to about 75 kPa; (e) a separator for receiving the combination of refrigerant vapor and refrigerant liquid from said at least first expander and for producing at least one liquid effluent stream comprising approximately said low pressure liquid refrigerant and substantially no vapor refrigerant, and a low pressure vapor stream comprising approximately said low pressure refrigerant vapor and substantially no liquid refrigerant; and (f) an evaporator fluidly connected to at least a portion of at least one liquid output stream from the separator for evaporating at least a portion of such stream by absorbing heat from a heat source to be cooled to produce a low pressure refrigerant vapor at a pressure of about 45 to about 75 kPa, with at least a portion of the refrigerant vapor from the evaporator fluidly connected to the compressor suction; Cooling system including:

11. 11. The refrigeration system of claim 10, wherein the refrigerant comprises at least about 80% by weight trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze).

12. 11. The refrigeration system of claim 10, wherein the refrigerant comprises at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd).

13. 1. A cooling system of the type having a heat source to be cooled and a heat sink capable of rejecting heat therein, It has a capacity of about 2 to about 30 tons, (a) a heat transfer composition in a closed-loop refrigeration circuit comprising a refrigerant having combustion inhibiting properties, preferably comprising at least about 95% by weight trans-1-chloro-3,3,3-trifluoropropene (trans-1233zd) or at least about 80% trans-1,3,3,3-tetrafluoropropene (trans-HFO-1234ze); (b) at least one sensor disposed within an area proximate to the heat source to be cooled for sensing the presence of a flame or fire within such area; (c) a port in the closed-loop refrigeration circuit that is in communication with a relatively high pressure refrigerant vapor contained within the refrigeration system; (d) a valve in fluid communication with the port responsive to the sensor for discharging at least a portion of the refrigerant vapor from the refrigeration system; and (e) a conduit for conveying refrigerant vapor to such adjacent region; Cooling system including:

Images