U.S. patent application number 15/400891 was filed with the patent office on 2017-07-06 for high efficiency air conditioning systems and methods.
The applicant listed for this patent is HONEYWELL INTERNATIONAL INC.. Invention is credited to Michael Petersen, Ankit Sethi, Elizabet del Carmen Vera Becerra, Samuel F. Yana Motta.
Application Number | 20170191702 15/400891 |
Document ID | / |
Family ID | 59226125 |
Filed Date | 2017-07-06 |
United States Patent
Application |
20170191702 |
Kind Code |
A1 |
Petersen; Michael ; et
al. |
July 6, 2017 |
HIGH EFFICIENCY AIR CONDITIONING SYSTEMS AND METHODS
Abstract
Disclosed are refrigeration systems of the type having a heat
source to be cooled and a heat sink into which heat can be
rejected, said system preferably having a capacity of from about 2
to about 30 tons and comprising: (a) a heat transfer composition
comprising a refrigerant comprising at least about 80% by weight of
trans1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)) or at least
about 80% by weight of trans1,3,3,3-tetrafluoropropene
(HFO-1234ze(E)); (b) a centrifugal compressor having: (i) a
refrigerant suction for receiving a relatively low-pressure
refrigerant vapor at a pressure of from about 40 to about 350 kPa
and (ii) a discharge for discharging a relatively high pressure
refrigerant vapor at a pressure wherein the discharge:suction
pressure ratio is at least about 2:1; (c) a condenser operating at
temperature in the range of from about 10.degree. C. to about
60.degree. C.; (d) and expander for producing relatively cold low
pressure refrigerant liquid; (e) a high efficiency evaporator,
preferably a flooded evaporator, fluidly connected to said expander
for receiving said low pressure refrigerant liquid from said
expander and evaporating said low pressure refrigerant liquid by
absorbing heat from said source to be cooled to produce a
relatively low pressure refrigerant vapor at a pressure of from
about 40 to about 350 kPa, said refrigerant vapor exiting from said
evaporator preferably having no substantial superheat; (f) at least
one heat exchanger fluidly connected between said evaporator and
said refrigerant suction of said compressor.
Inventors: |
Petersen; Michael; (Clarence
Center, NY) ; Yana Motta; Samuel F.; (East Amherst,
NY) ; Sethi; Ankit; (Buffalo, NY) ; Vera
Becerra; Elizabet del Carmen; (Amherst, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONEYWELL INTERNATIONAL INC. |
Morris Plains |
NJ |
US |
|
|
Family ID: |
59226125 |
Appl. No.: |
15/400891 |
Filed: |
January 6, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62275382 |
Jan 6, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 1/053 20130101;
F25B 1/10 20130101; C09K 5/044 20130101; F25B 2400/13 20130101;
F25B 2400/23 20130101; F25B 2400/12 20130101; C09K 2205/126
20130101; F25B 2400/121 20130101; C09K 5/045 20130101; F25B 45/00
20130101; F25B 40/00 20130101 |
International
Class: |
F25B 1/053 20060101
F25B001/053; F25B 45/00 20060101 F25B045/00; F25B 1/10 20060101
F25B001/10 |
Claims
1. A refrigeration system of the type having a heat source to be
cooled and a heat sink into which heat can be rejected, said system
having a capacity of from about 2 to about 30 tons and comprising:
(a) a heat transfer composition comprising a refrigerant comprising
at least about 95% by weight of
trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least
about 80% by weight of trans1,3,3,3-tetrafluoropropene
(transHFO-1234ze); (b) a centrifugal compressor having a
refrigerant suction for receiving low-pressure refrigerant vapor at
a pressure of from about 45 to about 75 kPa and discharge for
discharging high pressure refrigerant vapor at a pressure of from
about 100 to about 520 kPa, said compressor having an efficiency of
at least about 0.65; (c) a condenser fluidly connected to said
refrigerant discharge of said compressor for receiving said high
pressure refrigerant vapor and condensing at least a substantial
portion of said refrigerant vapor by heat transfer with said heat
sink to produce high pressure refrigerant liquid at temperature in
the range of from about 10.degree. C. to about 60.degree. C.; (d)
an expander fluidly connected to said condenser for substantially
isoenthalpically reducing the pressure of said high pressure
refrigerant liquid to produce low pressure refrigerant liquid at a
pressure of from about 45 to about 75 kPa; (e) an evaporator
fluidly connected to said expander for receiving said low pressure
refrigerant liquid and evaporating said low pressure refrigerant
liquid by absorbing heat from said source to be cooled to produce a
low pressure refrigerant vapor at a pressure of from about 45 to
about 75 kPa; and (f) at least one heat exchanger fluidly connected
between said evaporator and said refrigerant suction of said
compressor, said at least one heat exchanger receiving at least a
portion of said low pressure refrigerant vapor from said evaporator
and heating said low pressure refrigerant vapor to produce a low
pressure refrigerant vapor having a temperature at least about 5 C
greater than the temperature of the vapor entering said at least
one heat exchanger, said high temperature refrigerant vapor from
said at least one heat exchanger fluidly connected to said
compressor suction for providing low-pressure refrigerant vapor to
said compressor.
2. The refrigeration system of claim 1 wherein said refrigerant
comprises at least about 80% by weight of
trans1,3,3,3-tetrafluoropropene (transHFO-1234ze)
3. The refrigeration system of claim 1 wherein said refrigerant
comprises at least about 95% by weight of
trans1-chloro-3,3,3-trifluoropropene (trans1233zd).
4. A refrigeration system of the type having a heat source to be
cooled and a heat sink into which heat can be rejected, said system
having a capacity of from about 2 to about 30 tons and comprising:
(a) a heat transfer composition comprising a refrigerant comprising
at least about 95% by weight of
trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least
about 70% by weight of trans1,3,3,3-tetrafluoropropene
(transHFO-1234ze); (b) a centrifugal compressor having a first
stage and at least a second stage, each of said stages having a
refrigerant suction for receiving a relatively low-pressure
refrigerant vapor at pressure of from about 45 to about 75 kPa and
a refrigerant discharge for discharging a relatively higher
pressure refrigerant vapor at a pressure of from about 100 to about
520 kPa, said compressor having an efficiency of at least about
0.65; (c) a condenser fluidly connected to said refrigerant
discharge of said at least second stage of said compressor for
receiving said high pressure refrigerant vapor from said at least a
second stage and condensing at least a substantial portion of said
refrigerant vapor by heat transfer with said heat sink to produce
high pressure refrigerant liquid at temperature in the range of
from about 10.degree. C. to about 60.degree. C.; (d) at least a
first expander fluidly connected to said condenser for
substantially isoenthalpically reducing the pressure of at least a
first portion of said high pressure refrigerant liquid to produce
first low pressure refrigerant liquid at a pressure of from about
45 to about 75 kPa; (e) at least a second expander fluidly
connected to said condenser for substantially isoenthalpically
reducing the pressure of at least a second portion of said high
pressure refrigerant liquid to produce second low pressure
refrigerant liquid at a pressure of from about 100 to about 520
kPa; (f) an evaporator fluidly connected to said at least said
first expander for receiving said first low pressure refrigerant
liquid and evaporating said low pressure refrigerant liquid by
absorbing heat from said source to be cooled to produce a low
pressure refrigerant vapor at a pressure of from about 100 to about
520 kPa, at least a portion of said refrigerant vapor from said
evaporator being fluidly connected to said first stage compressor
suction; and (g) at least one heat exchanger and/or at least one
flash tank fluidly connected between said second expander and said
suction of said at least second stage for receiving at least a
portion of said second low pressure refrigerant liquid and
discharging therefrom refrigerant vapor at about the pressure of
said second low pressure refrigerant liquid, said refrigerant vapor
at about the pressure of said second low pressure refrigerant
liquid being fluidly connected to said second stage compressor
suction.
5. The refrigeration system of claim 4 wherein said refrigerant
comprises at least about 80% by weight of
trans1,3,3,3-tetrafluoropropene (transHFO-1234ze).
6. The refrigeration system of claim 4 wherein said refrigerant
comprises at least about 95% by weight of
trans1-chloro-3,3,3-trifluoropropene (trans1233zd).
7. A refrigeration system of the type having a heat source to be
cooled and a heat sink into which heat can be rejected, said system
having a capacity of from about 2 to about 5 tons and comprising:
(a) a heat transfer composition comprising a refrigerant comprising
at least about 95% by weight of
trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least
about 80% by weight of trans1,3,3,3-tetrafluoropropene
(transHFO-1234ze); (b) a centrifugal compressor having a
refrigerant suction for receiving a relatively low-pressure
refrigerant vapor at pressure of from about 45 to about 75 kPa and
a refrigerant discharge for discharging a relatively higher
pressure refrigerant vapor at a pressure of from about 100 to about
520 kPa, said compressor having an efficiency of at least about
0.65; (c) a condenser fluidly connected to said refrigerant
discharge of said compressor for receiving said high pressure
refrigerant vapor from said compressor and condensing at least a
substantial portion of said refrigerant vapor by heat transfer with
said heat sink to produce high pressure refrigerant liquid at
temperature in the range of from about 45 to about 75 kPa; (d) at
least a first expander fluidly connected to said condenser for
substantially isoenthalpically reducing the pressure of at least a
first portion of said high pressure refrigerant liquid to produce
first low pressure refrigerant liquid at a pressure of from about
45 to about 75 kPa; and (e) an evaporator fluidly connected to said
at least said first expander for receiving said low pressure
refrigerant liquid and evaporating at least a portion of said low
pressure refrigerant liquid by absorbing heat from said source to
be cooled to produce a low pressure refrigerant vapor at a pressure
of from about 45 to about 75 kPa, at least a portion of said
refrigerant vapor from said evaporator being fluidly connected to
said compressor suction, wherein at least one of said condenser and
said evaporator is formed in substantial part of aluminum.
8. The refrigeration system of claim 7 wherein said refrigerant
comprises at least about 80% by weight of
trans1,3,3,3-tetrafluoropropene (transHFO-1234ze).
9. The refrigeration system of claim 7 wherein said refrigerant
comprises at least about 95% by weight of
trans1-chloro-3,3,3-trifluoropropene (trans1233zd).
10. A refrigeration system of the type having a heat source to be
cooled and a heat sink into which heat can be rejected, said system
having a capacity of from about 2 to about 30 tons and comprising:
(a) a heat transfer composition comprising a refrigerant comprising
at least about 95% by weight of
trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or at least
about 80% by weight of trans1,3,3,3-tetrafluoropropene
(transHFO-1234ze); (b) a centrifugal compressor having a
refrigerant suction for receiving a relatively low-pressure
refrigerant vapor at pressure of from about 45 to about 75 kPa and
a refrigerant discharge for discharging a relatively higher
pressure refrigerant vapor at a pressure of from about 100 kPa to
about 520 kPa, said compressor having an efficiency of at least
about 0.65; (c) a condenser fluidly connected to said refrigerant
discharge of said compressor for receiving said high pressure
refrigerant vapor from said compressor and condensing at least a
substantial portion of said refrigerant vapor by heat transfer with
said heat sink to produce high pressure refrigerant liquid at
temperature in the range of from about 10.degree. C. to about
60.degree. C.; (d) at least a first expander fluidly connected to
said condenser for substantially isoenthalpically reducing the
pressure of at least a first portion of said high pressure
refrigerant liquid to produce a low pressure stream comprising a
combination of refrigerant liquid and refrigerant vapor at a
pressure of from about 45 to about 75 kPa; (e) a separator for
receiving at least the combination of refrigerant vapor and
refrigerant liquid from said at least first expander and producing
at least one liquid effluent stream comprising liquid refrigerant
at about said low pressure and no substantial vapor refrigerant and
a low pressure vapor stream comprising refrigerant vapor at about
said low pressure and no substantial liquid refrigerant; and (f) an
evaporator fluidly connected to at least a portion of said at least
one liquid effluent stream from said separator and evaporating at
least a portion of said stream by absorbing heat from said source
to be cooled to produce a low pressure refrigerant vapor at a
pressure of from about 45 to about 75 kPa, at least a portion of
said refrigerant vapor from said evaporator being fluidly connected
to said compressor suction.
11. The refrigeration system of claim 10 wherein said refrigerant
comprises at least about 80% by weight of
trans1,3,3,3-tetrafluoropropene (transHFO-1234ze).
12. The refrigeration system of claim 10 wherein said refrigerant
comprises at least about 95% by weight of
trans1-chloro-3,3,3-trifluoropropene (trans1233zd).
13. A refrigeration system of the type having a heat source to be
cooled and a heat sink into which heat can be rejected, said system
having a capacity of from about 2 to about 30 tons and comprising:
(a) a heat transfer composition comprising a refrigerant having
fire suppression features, preferably comprising at least about 95%
by weight of trans1-chloro-3,3,3-trifluoropropene (trans1233zd) or
at least about 80% of trans1,3,3,3-tetrafluoropropene
(transHFO-1234ze), in a closed loop refrigeration circuit; (b) at
least one sensor located in an area in the proximity of the heat
source being cooled for sensing the existence of flame or fire in
said proximity; (c) a port in said closed loop refrigeration
circuit in communication with relatively high pressure refrigerant
vapor contained in said refrigeration system; (d) a valve
responsive to said sensor and fluidly connected to port for
releasing at least a portion of said refrigerant vapor from said
refrigeration system; and (e) a conduit for transporting said
refrigerant vapor to said proximity.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to and claims the priority
benefit of U.S. Provisional Application 62/275,382 filed Jan. 6,
2016, the entirety of which is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to air conditioning systems
and more particularly to such systems which utilize centrifugal
compressors and have a refrigeration capacity in the range of up to
about 30 tons.
BACKGROUND
[0003] Certain halogenated olefins, including the compounds
1-chloro-3,3,3-trifluoropropene (HFCO-1233zd) and
1,3,3,3-tetrafluoropropene (HFO-1234ze) have been suggested to use
in vapor compression refrigeration systems. See U.S. Pat. No.
7,833,433, A standard vapor compression system is described in the
'433 patent as including a compressor for compressing refrigerant
vapor to produce a relatively elevated pressure and temperature
vapor. An example of such a system is illustrated herein as FIG. P.
In such a system a refrigerant is introduced at a relatively low
pressure into the suction side of a compressor 11 via a conduit 19A
and a high pressure refrigerant is discharged and sent via conduit
19B to condenser 12. Heat is removed from this high temperature
refrigerant vapor by condensing the refrigerant vapor in condenser
12 to produce a relatively high pressure liquid refrigerant which
enters a conduit 15A. The relatively high pressure liquid then
undergoes a nominally isoenthalpic reduction in pressure in an
expansion device 14 to produce a relatively low temperature, low
pressure liquid, which is then vaporized by heat transferred from
the body or fluid to be cooled in evaporator 24. The low pressure
vapor thus produced is returned to the suction side of the
compressor via conduit 19A, thus completing the cycle.
[0004] The '433 patent suggests generally that the refrigerant
compositions disclosed therein can be used in a variety of
different cooling operations that employ a vapor compression
system, including chiller systems that use centrifugal compressors.
Typically, centrifugal chillers are large capacity systems, that
is, systems having capacities greater than 50 tons. Most typically
such systems are in the range of 50 to 150 tons of refrigerating
capacity, with certain systems going as high as 8500 tons.
[0005] Applicants have come to appreciate that certain unexpected
problems exist in connection with efforts to use transHFCO-1233zd
and/or transHFO-1234ze in small capacity air conditioning systems
that use high efficiency centrifugal compressors. As described in
detail hereinafter, applicants have unexpectedly found that these
problems can be overcome by utilizing one or more specialized
configurations in the air conditioning system that allow the use of
high efficiency equipment, including high efficiency compressors
and evaporators, while at the same time overcoming the problems
that applicants have recognized with the use of transHFCO-1233rd
and/or transHFO-1234ze in such systems.
SUMMARY
[0006] Applicants have come to appreciate that it is highly
desirable in many applications to provide low capacity air
conditioning systems utilizing highly efficient centrifugal
compressors and high efficiency evaporators. However, applicants
have also come to appreciate that the use of refrigerant
compositions comprising high percentages (e.g., above about 80% by
weight) of HCFO-1233zd(E) or high percentages (e.g., above about
80% by weight) of HFO-1234ze(E), can pose serious problems for the
reliability and/or effectiveness and/or efficiency of such
systems.
[0007] For example, it is highly desirable in certain air
conditioning systems to utilize a flooded evaporator because such
heat exchange equipment allows a highly efficient heat transfer to
the liquid refrigerant to occur. This highly efficient operation is
due, at least in part, to the fact that in such equipment the heat
transfer surfaces are essentially substantially covered by liquid
refrigerant. However, as a consequence of using such highly
efficient equipment, the vapor which exits from such an evaporator
is essentially at saturated conditions, that is, possesses little
or no superheat. This is an advantage from an efficiency
standpoint, although it becomes especially important in such
circumstances to ensure that the vapor which enters the compressor
at or near saturation conditions does not condense. This is because
the presence of such liquid refrigerant in the compressor will have
negative consequences on the efficiency and/or the reliability of
the compressor operation. Under typical operating conditions using
other refrigerants, the use of saturated or near saturated
refrigerant vapor at the compressor suction would not present a
problem because during the nominal isentropic expansion that occurs
in high-efficiency compressors heat is added to the refrigerant
vapor and generates at least about 5.degree. of superheat upon
discharge from the compressor.
[0008] Applicants have come to appreciate, however, that problems
will occur when using the preferred refrigerant compositions of the
present invention in systems using high efficiency centrifugal
compressors under conditions of the type that are preferred herein.
More specifically, applicants have found that the preferred
refrigerant compositions of the present invention will not under
typical conditions produce the normal or expected amount of
superheat during high efficiency compression. In fact, applicants
have found that for highly efficient centrifugal compressor
operation a "wet vapor" would be discharged from the compressor in
the absence of the solution or solutions provided herein. As used
herein, the term "wet vapor" refers to a vapor which has condensed
liquid entrained therein. As is well known to those skilled in the
art, the presence of such a vapor in the compressor can be highly
detrimental to the efficient and or reliable operation of
centrifugal compressors. Accordingly, applicants have found that
use of the refrigerants according to the preferred aspects of the
present invention can produce, in the absence of the present
solutions, unexpected problems in the operation of high-efficiency
centrifugal compressors, especially in applications which also
utilize high-efficiency, low or no superheat evaporators.
Nevertheless, applicants have also come to appreciate that it is
highly desirable to operate such systems using the preferred heat
transfer compositions of the present invention, since such
operations are able to provide advantageous, environmentally
friendly operation.
[0009] In order to overcome the problems and difficulties that
applicants have come to recognize, one aspect of the present
invention provides a refrigeration system of the type having a heat
source to be cooled and a heat sink into which heat can be
rejected, said system preferably having a capacity of from about 2
to about 30 tons and comprising:
[0010] (a) a heat transfer composition comprising a refrigerant
comprising at least about 80% by weight of
trans1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)) or at least
about 80% by weight of trans1,3,3,3-tetrafluoropropene
(HFO-1234ze(E)),
[0011] (b) a centrifugal compressor having: (i) a refrigerant
suction for receiving a relatively low-pressure refrigerant vapor
at a pressure of from about 40 to about 350 kPa and (ii) a
discharge for discharging a relatively high pressure refrigerant
vapor at a pressure wherein the discharge:suction pressure ratio is
at least about 2:1;
[0012] (c) a condenser fluidly connected to said refrigerant
discharge of said compressor for receiving at least a portion of
said compressor discharge refrigerant vapor and condensing at least
a substantial portion of said refrigerant vapor, and preferably
substantially all of said refrigerant vapor, by heat transfer with
said heat sink to produce a relatively high pressure refrigerant
liquid at temperature in the range of from about 10.degree. C. to
about 60.degree. C.;
[0013] (d) an expander fluidly connected to said condenser for
substantially isoenthalpically reducing the pressure of said high
pressure refrigerant liquid to produce low pressure refrigerant
liquid at a pressure of from about 40 to about 350 kPa;
[0014] (e) a high efficiency evaporator, preferably a flooded
evaporator, fluidly connected to said expander for receiving said
low pressure refrigerant liquid from said expander and evaporating
said low pressure refrigerant liquid by absorbing heat from said
source to be cooled to produce a relatively low pressure
refrigerant vapor at a pressure of from about 40 to about 350 kPa,
said refrigerant vapor exiting from said evaporator preferably
having no substantial superheat;
[0015] (f) at least one heat exchanger fluidly connected between
said evaporator and said refrigerant suction of said compressor,
said at least one heat exchanger receiving at least a portion of
said low pressure refrigerant vapor from said evaporator and
heating said low pressure refrigerant vapor to produce a low
pressure refrigerant vapor having a temperature at least about
5.degree. C. greater than the temperature of the vapor entering
said at least one heat exchanger, said high temperature refrigerant
vapor from said at least one heat exchanger fluidly connected to
said compressor suction for providing low-pressure refrigerant
vapor to said compressor.
[0016] As used herein, the term "capacity" defined in terms of
number of "tons" refers to a heat transfer rate equivalent to the
amount of heat required to melt one ton (2000 lb; 907 kg) of ice at
0 C (32 F) in 24 hours and generally equates to about 12,000
BTU/hour.
[0017] Other embodiments and aspects of the invention are disclosed
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. P is an illustration of a prior art heat transfer
system
[0019] FIG. 1 is a generalized process flow diagram of one
preferred embodiment of an air conditioning system according to the
present invention.
[0020] FIG. 2 is a generalized process flow diagram of another
preferred embodiment of an air conditioning system according to the
present invention.
[0021] FIG. 3 is a generalized process flow diagram of another
preferred embodiment of an air conditioning system according to the
present invention.
[0022] FIG. 4A is a generalized process flow diagram of another
preferred embodiment of an air conditioning system according to the
present invention.
[0023] FIG. 4B is a more specific process flow diagram of a
preferred embodiment of an air conditioning system having a flame
suppression feature according to one aspect of the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0024] Preferred Heat Transfer Compositions
[0025] In each of the embodiments described herein the system
includes a heat transfer composition comprising refrigerant and
preferably but not necessarily a lubricant for the compressor.
Preferably the refrigerant comprises at least about 70% by weight,
or at least about 80% by weight of
trans1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)) or of
trans1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), and is a low
flammability and low toxicity refrigerant, preferably with a Class
A toxicity according to ASHRAE Standard 2013 and a flammability of
Class 1 or Class 2 or Class 2L according to ASHRAE Standard 34-2013
and described in Appendix B1 to ASHRAE Standard 34-2013.
[0026] In highly preferred embodiments, including embodiments of
the type disclosed herein which include providing a flame
suppression feature to the systems and methods, the refrigerant
comprises at least about 95% by weight, and in some embodiments
consists essentially of or consists of, HFCO-1233zd(E)
[0027] In other highly preferred embodiments, the refrigerant
comprises from about 1% by weight to about 5% by weight of a five
carbon saturated hydrocarbon, preferably one or more of
iso-pentane, n-pentane or neo-pentane, and in preferred aspects of
such embodiments the combination of said HFCO-1233zd(E) and said
pentane is in the form of an azeotropic composition. Such azeotrope
and azeotrope-like compositions are disclosed in U.S. Pat. No.
8,802,874, U.S. Pat. No. 8,163,196, and U.S. Pat. No. 8,703,006,
each of which is incorporated herein by reference. Heat transfer
compositions of the present invention which include refrigerant
compositions as described in this paragraph preferable include
lubricant comprising or consisting of POE and/or mineral oil and/or
alkyl benzene.
[0028] In highly preferred embodiments, including embodiments of
the type disclosed herein which include providing a flame
suppression feature to the systems and methods, the refrigerant
comprises from about 85% to about 90% by weight of by weight of
trans1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and from about 10%
by weight 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% of
trans1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) and about 12% by
weight of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). Heat
transfer compositions of the present invention which include
refrigerant compositions as described in this paragraph preferable
include lubricant comprising or consisting of POE.
[0029] Those skilled in the art will appreciate in view of the
disclosures contained herein that such embodiments of the present
invention provide the advantage of utilizing only the relatively
safe (low toxicity and low flammability) low GWP refrigerants,
which make them highly preferred for use in a location proximate to
the humans or other animals occupying a dwelling, as is commonly
encountered in air conditioning applications.
[0030] The heat transfer compositions of the present invention
generally include a lubricant. However, embodiments of the present
invention include systems and methods which utilize compressors
which do not require a lubricant and/or does not require the
lubricant to be combined with the refrigerant. However, for those
preferred embodiments in which the lubricant and refrigerant are
included together as mixtures in one or more locations in the
system, the lubricant is preferably present in the system in
amounts of from about 30 to about 50 percent 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,
with other optional components as described hereinafter also being
possibly present. In preferred embodiments it is expected that heat
transfer composition of the present invention, particularly in the
form of the carry-over vapor from the compressor and in the form of
the liquid from the condenser and entering the evaporator,
comprises from about 97% to about 99.5% by weight of refrigerant of
the present invention and from about 0.5 to about 3% by weight of
lubricant, with such lubricant preferably being POE lubricant
and/or, mineral oil lubricant.
[0031] Other optional components include a compatibilizer, such as
propane, for the purpose of aiding compatibility and/or solubility
of the lubricant. When present, such compatibilizers, including
propane, butanes and pentanes, are preferably present in amounts of
from about 0.5 to about 5 percent by weight of the composition.
Combinations of surfactants and solubilizing agents may also be
added to the present compositions to aid oil solubility, as
disclosed by U.S. Pat. No. 6,516,837, the disclosure of which is
incorporated by reference. Commonly used refrigeration lubricants
such as Polyol Esters (POEs) and Poly Alkylene Glycols (PAGs),
silicone oil, mineral oil, alkyl benzenes (ABs) and
poly(alpha-olefin) (PAO) that are used in refrigeration machinery
with hydrofluorocarbon (HFC) refrigerants may be used with the
refrigerant compositions of the present invention. The preferred
lubricants of the present invention are selected from POEs and
mineral oils and alkyl benzenes.
Systems
[0032] The present refrigeration systems and methods are
particularly well adapted for use in low capacity air conditioning
systems, that is, systems having a capacity of 30 tons or less,
particularly in residential air conditioning, particularly
residential air conditioning having a capacity of from about 2 to
about 5 tons, and commercial packaged rooftop air conditioning
units, particularly having a capacity of from about 5 to about 30
tons.
Embodiments of the Type Illustrated in FIG. 1
[0033] A preferred air conditioning system, designated generally at
10, is illustrated in FIG. 1. Such a preferred air conditioning
system comprises compressor 11, condenser 12, evaporator 24
(preferably a flooded evaporator), expansion valve 14, and
suction-line heat exchanger 30, together with any of the associated
conduits 15A, 15B, 16A and 16B and other connecting and related
equipment (not shown). In operation, the refrigerant according to
the present invention is discharged from compressor 11 as a
relatively high pressure refrigerant vapor, which may include
entrained lubricant, and which then is transported via conduit 19C
to condenser 12. In condenser 12 the refrigerant vapor transfers a
portion of its heat, preferably via a phase change and preferably
to ambient air, and produces an effluent stream comprising at least
partially, and preferably substantially fully, condensed
refrigerant. The refrigerant effluent from the condenser 12 is
transported via conduit 15A to suction-line heat exchanger 30 where
it loses additional heat to the effluent from the evaporator 24, as
is explained more fully hereinafter. The effluent from the
suction/liquid line heat exchanger 30 is then transported via
conduit 15B to expansion valve 14 where the pressure of the
refrigerant is reduced, preferably substantially isoenthalpically,
which in turn reduces the temperature of the refrigerant. The
relatively cold liquid refrigerant from the expansion valve 14
flows to receiver tank 18 which provides a reservoir of cold liquid
refrigerant that is fed by way of a control valve (not shown) in
conduit 19A into the evaporator 24 where it absorbs heat from the
body or fluid being cooled, preferably the ambient air within a
dwelling or other space being cooled. The refrigerant effluent
vapor from the evaporator 24, which is preferably a substantially
saturated refrigerant vapor with substantially no super heat (e.g.
the superheat of the vapor leaving the evaporator is less than
about 1.degree. C. and more preferably less than about 0.5.degree.
C., and even more preferably of less than about 0.1.degree. C.) is
then transported via conduit 19A to the suction/liquid line heat
exchanger 30 where it gains heat from the condenser effluent from
conduit 15A and produces a refrigerant vapor at a higher
temperature, which is transported by conduit 16B to the inlet of
the compressor 11. In preferred embodiments, the vapor leaving the
suction line heat exchanger has a temperature that is at least
about 5.degree. C., and even more preferably at least about
7.degree. C., higher than the substantially saturated vapor which
enters the suction line heat exchanger. The high temperature
refrigerant vapor is then transported to the suction of the
compressor 11 where it is compressed as described above.
[0034] In preferred embodiments in which the refrigerant comprises
at least about 90% by weight, preferably consisting essentially of,
and preferably consisting of, HCFO-1233zd(E), the operating
conditions correspond to the values described in the table
below:
TABLE-US-00001 PREFERRED RANGE COMPRESSOR Pressure, 45-75 SUCTION
kPa Temperature, 0.degree.-10.degree. .degree. C. COMPRESSOR
Pressure, 105-520 DISCHARGE kPa Temperature, 20.degree.-70.degree.
.degree. C. CONDENSER Pressure, 105-520 kPa Temperature,
10.degree.-60.degree. .degree. C. EVAPORATOR Pressure, 45-75 kPa
Temperature, 0.degree.-10.degree. C..degree.
[0035] In preferred embodiments in which the refrigerant comprises
at least about 80% by weight, HFO-1234ze(E), and even more
preferably 88% by weight of HFO-1234ze(E) and 12% by weight of
HFC-227ea, the operating conditions correspond to the values
described in the table below:
TABLE-US-00002 PREFERRED RANGE COMPRESSOR Pressure, 210-310 SUCTION
kPa Temperature, 0.degree.-10.degree. .degree. C. COMPRESSOR
Pressure, 420-1600 DISCHARGE kPa Temperature, 20.degree.-70.degree.
.degree. C. CONDENSER Pressure, 420-1600 kPa Temperature,
10.degree.-60.degree. .degree. C. EVAPORATOR Pressure, 210-310 kPa
Temperature, 0.degree.-10.degree. .degree. C.
Embodiments of the Type Illustrated in FIG. 2
[0036] A further preferred air conditioning system, designated
generally at 10, is illustrated in FIG. 2. Such a preferred air
conditioning system comprises a multi-stage compressor, shown as a
two stage compressor 11, condenser 12, evaporator 24 (which is
preferably a flooded evaporator in some embodiments), expansion
valve 14, and vapor-injection heat exchanger 40, including
associated intermediate expansion valve 41, together with any of
the associated conduits 15A-15C and 19A-19D and other connecting
and related equipment (not shown and/or not labeled). In operation,
the refrigerant according to the present invention is discharged
from compressor 11 as a relatively high pressure refrigerant vapor,
which may include entrained lubricant, and which then is
transported via conduit 19D to condenser 12. In condenser 12 the
refrigerant vapor transfers a portion of its heat, preferably via a
phase change and preferably to ambient air, and produces an
effluent stream comprising at least partially, and preferably
substantially fully, condensed refrigerant. The refrigerant
effluent from the condenser 12 is transported via conduit 15A, and
a portion of the refrigerant effluent is routed via conduit 15B to
an intermediate expansion device 41 and another portion of the
effluent, preferably the remainder of the effluent, is transported
to the vapor injection heat exchanger 40.
[0037] In operation, the intermediate expansion device 41 lets the
pressure of the effluent stream down, preferably substantially
isoenthalpically, to about the pressure of the second stage suction
of compressor 11 or sufficiently above such pressure to account for
the pressure-drop through the heat exchanger 41 and associated
conduits, fixtures and the like. As a result of the pressure drop
across the expansion device 41, the temperature of the refrigerant
flowing to the heat exchanger 40 is reduced relative to the
temperature of the high pressure refrigerant which flows to the
heat exchanger 40. Heat is transferred in the heat exchanger 40
from the high pressure stream to the stream that passed through the
expansion valve 41. As a result, the temperature of the
intermediate pressure stream which exits the heat exchanger 40 is
higher, preferably by a temperature of at least about 5.degree. C.,
than the temperature of the inlet stream, thereby producing a
super-heated vapor stream that is transported to the second stage
of the compressor 11 via conduit 19C.
[0038] As the higher pressure stream transported by conduit 15A
travels through the heat exchanger 40 it loses heat to the lower
pressure stream exiting expansion devise 41 and exits the heat
exchanger through conduit 15C and then flows to receiver tank 18
which provides a reservoir of cold liquid refrigerant that is fed
by way of a control valve (not shown) in conduit 19A into the
evaporator 24. Ambient air to be cooled loses heat to the cold
liquid refrigerant in the evaporator which in turn vaporizes the
liquid refrigerant and produces refrigerant vapor with little or no
super heat, and this vapor then flows to the first stage of
compressor 11.
[0039] In preferred embodiments in which the refrigerant comprises
at least about 90% by weight, preferably consisting essentially of,
and preferably consisting of, HCFO-1233zd(E), the operating
conditions correspond to the values described in the table
below:
TABLE-US-00003 PREFERRED RANGE COMPRESSOR Pressure, 45-75 SUCTION
kPa Temperature, 0.degree.-10.degree. .degree. C. COMPRESSOR
Pressure, 105-520 DISCHARGE kPa Temperature, 20.degree.-70.degree.
.degree. C. CONDENSER Pressure, 105-520 kPa Temperature,
10.degree.-60.degree. .degree. C. EVAPORATOR Pressure, 45-75 kPa
Temperature, 0.degree.-10.degree. .degree. C.
[0040] In preferred embodiments in which the refrigerant comprises
at least about 80% by weight, HFO-1234ze(E), and even more
preferably 88% by weight of HFO-1234ze(E) and 12% by weight of
HFC-227ea, the operating conditions correspond to the values
described in the table below:
TABLE-US-00004 PREFERRED RANGE COMPRESSOR Pressure, 210-310 SUCTION
kPa Temperature, 0.degree.-10.degree. .degree. C. COMPRESSOR
Pressure, 420-1600 DISCHARGE kPa Temperature, 20.degree.-70.degree.
.degree. C. CONDENSER Pressure, 420-1600 kPa Temperature,
10.degree.-60.degree. .degree. C. EVAPORATOR Pressure, 210-310 kPa
Temperature, 0.degree.-10.degree. .degree. C.
Embodiments of the Type Illustrated in FIG. 3
[0041] A further preferred air conditioning system, designated
generally at 10, is illustrated in FIG. 3. Such a preferred air
conditioning system comprises a compressor 11, which may be a
multi-stage compressor of the type as described herein but in the
illustrated embodiment is shown as a single stage compressor,
condenser 12, evaporator 24 (which is preferably a flooded
evaporator in some embodiments), expansion valve 14, a flash gas
separator 18, together with any of the associated conduits 15A-15C
and 19A-19C and other connecting and related equipment (not shown
and/or not labeled). In operation, the refrigerant according to the
present invention is discharged from compressor 11 as a relatively
high pressure refrigerant vapor, which may include entrained
lubricant, and which then is transported via conduit 19C to
condenser 12. In condenser 12 the refrigerant vapor transfers a
portion of its heat, preferably via a phase change and preferably
to ambient external air, and produces an effluent stream comprising
at least partially, and preferably substantially fully, condensed
refrigerant. The refrigerant effluent from the condenser 12 is
transported via conduit 15A to expansion device 14. The lower
pressure stream exiting expander 14 flows through conduit 15B to
flash gas separator 18, which provides a reservoir of cold liquid
refrigerant that is fed by way of a control valve (not shown) in
conduit 15C into the evaporator 24. Ambient air to be cooled loses
heat to the cold liquid refrigerant in the evaporator 24, which in
turn vaporizes the liquid refrigerant and produces refrigerant
vapor with little or no super heat, and this vapor then flows to
the first stage of compressor 11. Flash gas generated during the
pressure let-down in expansion device 14 then flows through conduit
19B to the suction side of the compressor 11.
[0042] In preferred embodiments in which the refrigerant comprises
at least about 90% by weight, preferably consisting essentially of,
and preferably consisting of, HCFO-1233zd(E), the operating
conditions correspond to the values described in the table
below:
TABLE-US-00005 PREFERRED RANGE COMPRESSOR Pressure, kPa 45-75
SUCTION Temperature, 0.degree.-10.degree. .degree. C. COMPRESSOR
Pressure, kPa 105-520 DISCHARGE Temperature, 20.degree.-70.degree.
.degree. C. CONDENSER Pressure, kPa 105-520 Temperature,
10.degree.-60.degree. .degree. C. EVAPORATOR Pressure, kPa 45-75
Temperature, 0.degree.-10.degree. .degree. C.
[0043] In preferred embodiments in which the refrigerant comprises
at least about 80% by weight, HFO-1234zd(E), and even more
preferably 88% by weight of HFO-1234ze(E) and 12% by weight of
HFC-227ea, the operating conditions correspond to the values
described in the table below:
TABLE-US-00006 PREFERRED RANGE COMPRESSOR Pressure, 210-310 SUCTION
kPa Temperature, 0.degree.-10.degree. .degree. C. COMPRESSOR
Pressure, 420-1600 DISCHARGE kPa Temperature, 20.degree.-70.degree.
.degree. C. CONDENSER Pressure, 420-1600 kPa Temperature,
10.degree.-60.degree. .degree. C. EVAPORATOR Pressure, 210-310 kPa
Temperature, 0.degree.-10.degree. .degree. C.
Embodiments of the Type Illustrated in FIG. 4A
[0044] In a further preferred air conditioning systems, designated
generally at 10, is illustrated in FIG. 4A. Such a preferred air
conditioning system comprises a compressor 11, which may be a
multi-stage compressor of the type as described herein, condenser
12, evaporator 24 (which is preferably a flooded evaporator in some
embodiments), expansion valve 14, a high pressure receiver,
together with any of the associated conduits 15A-15C and 19A-19B
and other connecting and related equipment (not shown and/or not
labeled). In operation, the refrigerant according to the present
invention is discharged from compressor 11 as a relatively high
pressure refrigerant vapor, which may include entrained lubricant,
and which then is transported via conduit 19B to condenser 12. In
condenser 12 the refrigerant vapor transfers a portion of its heat,
preferably via a phase change and preferably to ambient external
air, and produces an effluent stream comprising at least partially,
and preferably substantially fully, condensed refrigerant. The
refrigerant effluent from the condenser 12 is transported via
conduit 15A to a high pressure receiver 50, which provides a
reservoir of liquid refrigerant. A sensor activated relief valve 60
is connected via a port or other form of connection to conduit 15A.
The sensor activated relief valve includes and/or is in
communication connection with, a sensor that monitors for flame,
smoke, flammable gas concentration or other indicia that a flame is
present or more likely to occur, said sensor being located in
vicinity of some portion of the refrigeration system, preferably
within the dwelling or other area being cooled. Since the preferred
refrigerants of the present invention have flammability suppression
properties, if the sensor detects flame and/or smoke (or other
indicia of the existence of possibility or increased likelihood of
fire), the sensor activated relief valve will open and release
refrigerant into the area in which it is located, thus assisting
with inhibition and/or elimination of the fire. The use of a high
pressure receiver ensures that a relatively large reservoir of high
pressure liquid refrigerant will be available in the event of such
an emergency situation. The remainder of the refrigeration system
can operate according to any one or more of the embodiments
described herein.
EXAMPLES
Example 1
1233zd without Suction Line Heat Exchanger
[0045] An air conditioning system according to a typical
arrangement as shown in the figure labeled Prior Art uses a
refrigerant consisting of HCFO-1233zd(E) according to the following
parameters:
[0046] Operating Conditions
[0047] 1--Evaporation temperature: 7.degree. C.
[0048] 2--Condensing temperature: Varying from 20.degree. C. to
60.degree. C.
[0049] 3--Isentropic efficiency: Varying from 0.7 to 0.8
[0050] 4--No subcooling or superheat
[0051] Since the system of this example has no superheat in the
vapor leaving the evaporator (which would be the case, for example,
with a flooded evaporator), a saturated vapor enters the suction
side of the centrifugal compressor. In normal operation with many
other refrigerants, the isentropic or near isentropic expansion of
the refrigerant vapor would produce a discharge gas with a
temperature that represents at least about 5.degree. C. of
superheat at the discharge pressures. This degree of super heat is
generally considered to be required in order to ensure safe and
reliable operation of the compressor to ensure that a "wet vapor"
does not exist in the compressor. For the system of the present
example, operation at several levels of near isoentropic
compression are evaluated to determine whether safe and reliable
operation is achieved using HCFO-1233zd(E). These results are
reported in Table 1 below:
TABLE-US-00007 TABLE 1 Compressor discharge superheat - .degree. C.
Condensing Isentropic Isentropic Isentropic temperature Isentropic
efficiency: efficiency: efficiency: [.degree. C.] efficiency: 1
0.80 0.75 0.70 20.degree. Wet vapor 2.46 3.37 4.41 25.degree. Wet
vapor 3.11 4.33 5.73 30.degree. Wet vapor 3.61 5.13 6.87 35.degree.
Wet vapor 3.98 5.78 7.83 40.degree. Wet vapor 4.22 6.28 8.63
45.degree. Wet vapor 4.34 6.65 9.28 50.degree. Wet vapor 4.36 6.9
9.79 55.degree. Wet vapor 4.29 7.04 10.17 60.degree. Wet vapor 4.13
7.07 10.43 (2.5% liquid in discharge)
[0052] As can be seen from the results reported in Table 1 above,
when the most efficient compressor is used (isentropic
efficiency=1), the vapor which exists the compressor includes at
least some proportion of liquid, thus producing a wet vapor
discharge, which as described above has serious negative
implications for efficient and/or reliable operation. When
compressor efficiency is decreased to 0.8, the desired level of
super heat is still not achieved for any of the tested condenser
temperatures. Even when compressor efficiency is decreased to 0.75
and 0.7, which itself is not a preferred option, the desirable
level of super heat is not achieved for the entire range of
condenser temperature conditions.
Example 2A
1233zd with Suction Line Heat Exchanger
[0053] An air conditioning system according to an arrangement
according to the present invention using a suction line heat
exchanger (SLHX) as illustrated in FIG. 1 and using a refrigerant
consisting of HCFO-1233zd(E) is tested according to the same
operating parameters of Example 1 for a single stage compressor
operating at 80% isentropic efficiency. Several levels of heat
exchanger efficiencies for the suction line heat exchanger are
examined, and the results are reported in Table 2A below:
TABLE-US-00008 TABLE 2A Compressor discharge superheat [.degree.
C.] at 80% isentropic efficiency Condensing SLHX SLHX SLHX
temperature effectiveness effectiveness effectiveness [.degree. C.]
0.3 0.5 0.7 20.degree. 6.47 9.13 11.78 25.degree. 8.71 12.42 16.11
30.degree. 10.82 15.6 20.35 35.degree. 12.83 18.67 24.48 40.degree.
14.72 21.65 28.52 45.degree. 16.51 24.53 32.47 50.degree. 18.22
27.32 36.33 55.degree. 19.83 30.03 40.11 60.degree. 21.37 32.66
43.82
[0054] As can be seen from the results as reported above, operation
according to the embodiment of the invention as illustrated in FIG.
1 produces at least about 5.degree. C. of superheat at the
compressor discharge for the whole range of condensing temperatures
tested.
Example 2B
Azeotropes with R1233zd
[0055] Example 2A is repeated except that a series of azeotropic
refrigerant blends based on HCFO-1233zd(E) as described in Table 2B
below are used in place of the refrigerant consisting of only
1233zd(E) as used in Example 2A. Acceptable operation is
achieved.
[0056] In addition, the transport properties of these additional
refrigerants is tested, together with the properties of refrigerant
consisting of HCFO-1233zd(E), and are reported below in Table
2B.
TABLE-US-00009 TABLE 2B Liquid Vapor Thermal Thermal Liquid Vapor
Conductivity Conductivity Viscosity Viscosity Refrigerant
Flammability (mW/m-K) (mW/m-K) (.mu.Pa-s) (.mu.Pa-s) 1233zd(E)
Non-flammable 80.2 9.2 605.5 10.4 (100%) (100%) (100%) (100%)
(100%) n-Pentane/1233zd(E) Non-flammable 82.2 9.4 572.3 10.1
(2.8%/97.2%) (103%) (102%) (95%) (97%) Iso-Pentane/1233zd(E)
Non-Flammable 83.0 9.6 549.1 10.0 (4.6%/95.4%) (104%) (104%) (91%)
(96%) Neo-pentane/1233zd(E) Non-flammable 81.5 9.6 557.3 10.1
(4.0%/96.0%) (102%) (104%) (92%) (97%)
Example 3A
1233zd with Suction Line Heat Exchanger
[0057] An air conditioning system according to the present
invention as illustrated in FIG. 1 is tested using a suction line
heat exchanger (SLHX) with an SLHX effectiveness of 0.5 and 0.7 and
using a refrigerant consisting of HCFO-1233zd(E) is tested
according to the same operating parameters of Example 1. This
testing provides a comparison of the relative effectiveness of such
systems with the system described in Example 1 (both systems using
a compressor efficiency of 80%) which does not use a SLHX, and this
comparison is reported in Table 3A below:
TABLE-US-00010 TABLE 3A Cooling COP of system with SLHX Condensing
[% of system without SLHX] temperature Suction line heat exchanger
Suction line heat exchanger [.degree. C.] effectiveness: 0.5
effectiveness: 0.7 20.degree. 100.20 100.29% 25.degree. 100.40
100.58% 30.degree. 100.68 100.98% 35.degree. 101.04 101.48%
40.degree. 101.49 102.13% 45.degree. 102.05 102.90% 50.degree.
102.73 103.86% 55.degree. 103.53 104.94% 60.degree. 104.47
106.27%
[0058] As can be seen from the results reported above in Table 3A,
in addition to overcoming the wet vapor problem, the system
according to the configuration of FIG. 1 produce an improvement in
overall system efficiency (COP) for all tested conditions.
Example 4A
1233zd with Multi-Stage Compressor
[0059] An air conditioning system according the present invention
using a two stage compressor according to the system configuration
as illustrated in FIG. 2 using a refrigerant consisting of
HCFO-1233zd(E) is tested over a series of condensing temperatures
ranging from 30 C to 60 C. The operating conditions for the
compressor at an isentropic efficiency of 80% and an evaporator
temperature of 7 C for each of these condenser temperatures is
reported in Table 4A1:
TABLE-US-00011 TABLE 4A1 Condensing Compressor inlet Intermediate
Discharge temperature [.degree. C.] temperature [kPa] pressure
[kPa] pressure [kPa] 30.degree. 64.6 100 155 35.degree. 64.6 109
183 40.degree. 64.6 118 216 45.degree. 64.6 128 252 50.degree. 64.6
138 293 55.degree. 64.6 148 340 60.degree. 64.6 159 390
[0060] The same air conditioning using the multi-stage compressor
arrangement as illustrated in FIG. 2 using a refrigerant consisting
of HCFO-1233zd(E) is tested and compared to a single compressor
stage operating according to the configuration in Example 1. In
addition, the same set of comparative tests are run for the
refrigerant consisting of R11. The results of these comparative
tests are reported in Table 4A2 below:
TABLE-US-00012 TABLE 4A2 R1233zd(E)(E) R11 % % Compared Compared to
Single to Single COP Stage COP Stage Single stage 3.78 100.0% 4.01
100.0% Two-stage 4.17 110.4% 4.28 106.9% Three-stage 4.36 115.5%
4.41 110.1%
[0061] As can be seen from the results reported above, a dramatic
improvement in system efficiency (COP) is realized utilizing the
configuration of the present invention, according to the
embodiments of the type illustrated in FIG. 2 is realized as a
result of using 2 and 3 stage compression, in amounts up to 115%
improvement. In addition, the test results reported above indicate
that the use of HCFO-1233zd(E) in both a two-stage and a
three-stage compressor operation produces a substantially better
improvement in efficiency (COP) compared to the improvement which
is realized in the same system but utilizing R-11.
Example 5
1233zd and 1233zd Blends with Flash Gas Separator
[0062] An air conditioning system according to an arrangement
according to the present invention using a flash gas separator as
illustrated in FIG. 3 and using a refrigerant consisting of
HCFO-1233zd(E) and the blends identified in Table 5 below are s
tested according to the same operating parameters of Example 1 for
a single stage compressor operating at 80% isentropic efficiency.
The evaporator is operated in flooded configuration and results in
a reduced pressure drop across the evaporator and hence a higher
suction pressure in the compressor. In addition, since the since
the pressure in the system is relatively low as a result of the use
of a refrigerant consisting of HCFO-1233zd(E) and the blends in
Table 5, compact heat exchangers made from low cost materials can
be use. For example, round tube-fin and/or microchannel heat
exchangers could be made of aluminum instead of copper. This
configuration offers superior heat transfer performance, low weight
and compact heat transfer systems.
Example 6
1233zd(E) and 1233zd(E) Blends with Sensor Activated Relief
Valve
[0063] An air conditioning system according to an arrangement
according to the present invention using a sensor activated relief
valve as illustrated in FIGS. 4A and 4B and using a refrigerant
consisting of HCFO-1233zd(E) and each of the refrigerants disclosed
in Table 2B is tested. The sensor activated relief valve is
preferably a solenoid type valve. The sensor that is used measures
the natural gas concentration in a residential furnace unit. In
case of a fuel leak, such as for example a natural gas leak, of the
burner set up of the furnace the sensor would detect elevated gas
concentrations, for example 1000 ppm, activating the solenoid
valve. The activated valve would open and release the R1233zd(E)
into this flammable natural gas atmosphere. Due to the fire
suppressing properties of the R1233zd(E) the likeliness of a fire
would be reduced by inhibiting and/or eliminating the fire
condition in proximity to the relief valve which is located in
proximity to the sensed flammable atmosphere. Thus, fire conditions
or conditions indicating an increased likelihood of a fire is
detected by the sensor and the relief valve is opened, inhibiting
and/or eliminating the fire condition in proximity to the relief
valve which is located in proximity to the sensed flame and/or
sensed condition.
Example 7A
1234ze(E) Blends without Suction Line Heat Exchanger
[0064] An air conditioning system according to a typical
arrangement as shown in the figure labeled Prior Art uses a
refrigerant consisting of about 88% by weight of HFO-1234ze(E) and
about 12% by weight of R227ea according to the following
parameters:
[0065] Operating Conditions--Prior Art
[0066] 1--Evaporation temperature: 7.degree. C.
[0067] 2--Condensing temperature: Varying from 20.degree. C. to
60.degree. C.
[0068] 3--Isentropic efficiency: 0.7-0.8
[0069] 4--No subcooling or superheat
[0070] Since the system of this example has no superheat in the
vapor leaving the evaporator (which would be the case, for example,
with a flooded evaporator), a saturated vapor enters the suction
side of the centrifugal compressor. In normal operation with many
other refrigerants, the isentropic or near isentropic expansion of
the refrigerant vapor would produce a discharge gas with a
temperature that represents at least about 5.degree. C. of
superheat at the discharge pressures. This degree of super heat is
generally considered to be required in order to ensure safe and
reliable operation of the compressor to ensure that a "wet vapor"
does not exist in the compressor. For the system of the present
example, operation at several levels of near isoentropic
compression are evaluated to determine whether safe and reliable
operation is achieved using the above-noted blend of HFO-1234ze(E)
and R-227ea. These results are reported in Table 7A below:
TABLE-US-00013 TABLE 7A Compressor discharge superheat [.degree.
C.] Condensing Isentropic Isentropic Isentropic temperature
efficiency: efficiency: efficiency: [.degree. C.] 0.70 0.75 0.80
20.degree. 2.65 1.87 1.19 25.degree. 3.41 2.38 1.47 30.degree. 4.06
2.79 1.68 35.degree. 4.6 3.12 1.82 40.degree. 5.06 3.39 1.93
45.degree. 5.45 3.61 2 50.degree. 5.78 3.79 2.06 55.degree. 6.07
3.96 2.12 60.degree. 6.34 4.13 2.21
[0071] As can be seen from the results reported in Table 7 above,
all but five of the conditions tested fail to produce the minimum
level of of 5.degree. C. superheat in the compressor discharge, and
the conditions which do produce more than this minimum of super
heat use the undesirably low isentropic efficiency of 0.7 at high
condenser temperatures.
Example 7B
1234ze Blend with Suction Line Heat Exchanger
[0072] An air conditioning system according to an arrangement
according to the present invention using a suction line heat
exchanger (SLHX) as illustrated in FIG. 1 and using a refrigerant
consisting of about 88% by weight of HFO-1234ze(E) and about 12% by
weight of R227ea is tested according to the same operating
parameters of Example 7 for a single stage compressor operating at
80% isentropic efficiency. Several levels of heat exchanger
efficiencies for the suction line heat exchanger are examined, and
the results are reported in Table 7B below:
TABLE-US-00014 TABLE 7B Compressor discharge superheat [.degree.
C.] at 80% isentropic efficiency Condensing SLHX SLHX SLHX
temperature effectiveness effectiveness effectiveness [.degree. C.]
0.3 0.5 0.7 20.degree. 5.11 7.72 10.32 25.degree. 6.9 10.51 14.12
30.degree. 8.61 13.23 17.84 35.degree. 10.25 15.86 21.47 40.degree.
11.83 18.43 25.03 45.degree. 13.35 20.94 28.53 50.degree. 14.82
23.38 31.96 55.degree. 16.26 25.78 35.33 60.degree. 17.66 28.13
38.65
[0073] As can be seen from the results as reported in Table 7B
above, operation according to the embodiment of the invention as
illustrated in FIG. 1 produces at least about 5.degree. C. of
superheat at the compressor discharge for the whole range of
condensing temperatures tested.
Example 7C
1234ze Blend with Suction Line Heat Exchanger
[0074] An air conditioning system according to the present
invention as illustrated in FIG. 1 is tested using a suction line
heat exchanger (SLHX) with an SLHX effectiveness of 0.5 and 0.7 and
using a refrigerant consisting of about 88% by weight of
HFO-1234ze(E) and about 12% by weight of R227ea is tested according
to the same operating parameters of Example 7A. This testing
provides a comparison of the relative effectiveness of such systems
with the system described in Example 7A (both systems using a
compressor efficiency of 80%) which does not use a SLHX, and this
comparison is reported in Table 7C below:
TABLE-US-00015 TABLE 7C Cooling COP of system with SLHX Condensing
[% of system without SLHX] temperature Suction line heat exchanger
Suction line heat exchanger [.degree. C.] effectiveness: 0.5
effectiveness: 0.7 20.degree. 100.50% 100.73% 25.degree. 100.88%
101.27% 30.degree. 101.39% 101.99% 35.degree. 102.04% 102.90%
40.degree. 102.84% 104.04% 45.degree. 103.87% 105.46% 50.degree.
105.13% 107.21% 55.degree. 106.72% 109.39% 60.degree. 108.67%
112.05%
[0075] As can be seen from the results reported above in Table 7C,
in addition to overcoming the wet vapor problem, the systems
according to the configuration of FIG. 1 produce an improvement in
overall system efficiency (COP) for all tested conditions.
Example 8A
1234ze Blend with MultiStage Compressor
[0076] An air conditioning system according the present invention
using a two stage compressor and a three stage compressor according
to the system configurations as illustrated in FIG. 2 using a
refrigerant consisting of about 88% by weight of HFO-1234ze(E) and
about 12% by weight of R227ea is tested and compared to a single
compressor stage operating according to the configuration in
Example 1. In addition, the same set of comparative tests are run
for the refrigerant consisting of R134a. The results of these
comparative tests are reported in Table 8A below:
TABLE-US-00016 TABLE 8A R1234ze(E)/R227ea (0.88/0.12) R134a Single
stage 3.38 100.0% 3.44 100.0% Two-stage 3.92 116% 3.93 116.0%
Three-stage 4.10 121.3% 4.09 118.9%
[0077] As can be seen from the results reported above, a dramatic
improvement in system efficiency (COP) is realized utilizing the
configuration of the present invention, according to the
embodiments of the type illustrated in FIG. 2 as a result of using
2 and 3 stage compression, in amounts up to 115% improvement. In
addition, the test results reported above indicate that the use of
the HFO-1234ze(E)/227ea blend in both a two-stage and a 3 stage
compressor operation produces a substantially better improvement in
efficiency (COP) compared to the improvement which is realized in
the same system but utilizing R134a.
Example 9
[0078] In each of the Examples above the system includes plastic
components that in operation are in contact with the refrigerant.
These materials from which these components are made are compatible
and/or stable. Applicants have tested the stability of various
plastic materials when exposed to transHFCO-1233zd. Testing
comprises submerging samples of various plastics in
transHFCO-1233zd under ambient pressure conditions at room
temperature (approximately 24.degree. C.-25.degree. C.) for two (2)
weeks, after which the samples were removed from the
transHFCO-1233zd and allowed to outgas for 24 hours. The results
are reported in Table 9 below:
TABLE-US-00017 TABLE 9 AVE % AVE % SUBSTRATE (Plastics) WT. .DELTA.
VOL. .DELTA. ABS 3.35% 3.55% DELRIN .RTM. 0.54% 0.61% HDPE 1.70%
1.19% NYLON 66 -0.09% -0.09% POLYCARBONATE 3.55% 2.98% ULTEM .RTM.
Polyetherimide 0.035% -0.52% KYNAR .RTM. PVDF 0.13% -0.27% TEFLON
.RTM. 2.13% 3.93% POLYPROPYLENE 4.96% 3.68% PVC-TYPE 1 0.10% 0.04%
PET 0.08% 0.015%
As illustrated by the results in Table 5 above, the average percent
volume change for each of the tested plastic materials is less than
5%.
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