U.S. patent application number 15/357679 was filed with the patent office on 2017-05-18 for method for selecting lubricants for heat pumps.
The applicant listed for this patent is HONEYWELL INTERNATIONAL INC.. Invention is credited to CHRISTOPHER J. SEETON, MARK W. SPATZ, RAYMOND H. THOMAS, DAVID P. WILSON, SAMUEL F. YANA MOTTA.
Application Number | 20170137680 15/357679 |
Document ID | / |
Family ID | 41115077 |
Filed Date | 2017-05-18 |
United States Patent
Application |
20170137680 |
Kind Code |
A1 |
THOMAS; RAYMOND H. ; et
al. |
May 18, 2017 |
METHOD FOR SELECTING LUBRICANTS FOR HEAT PUMPS
Abstract
Provided is a method for selecting a lubricant and a refrigerant
for use in a vapor-compression refrigeration device such that the
combination of the lubricant and refrigerant produces a fluid
system having a lubricant-rich phase and a refrigerant-rich phase,
yet exhibits miscible-type properties.
Inventors: |
THOMAS; RAYMOND H.;
(Pendleton, NY) ; SEETON; CHRISTOPHER J.; (East
Amherst, NY) ; WILSON; DAVID P.; (East Amherst,
NY) ; YANA MOTTA; SAMUEL F.; (East Amherst, NY)
; SPATZ; MARK W.; (East Amherst, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONEYWELL INTERNATIONAL INC. |
MORRIS PLAINS |
NJ |
US |
|
|
Family ID: |
41115077 |
Appl. No.: |
15/357679 |
Filed: |
November 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14261882 |
Apr 25, 2014 |
9528037 |
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15357679 |
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13666166 |
Nov 1, 2012 |
8739559 |
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14261882 |
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12416734 |
Apr 1, 2009 |
8322149 |
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13666166 |
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61041474 |
Apr 1, 2008 |
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61043486 |
Apr 9, 2008 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 2209/1033 20130101;
C10N 2030/70 20200501; C09K 2205/24 20130101; C10M 2209/1085
20130101; C10M 2207/2835 20130101; C10N 2020/101 20200501; C09K
2205/126 20130101; C10N 2030/06 20130101; F25B 45/00 20130101; C10M
171/008 20130101; C09K 5/044 20130101; C09K 5/045 20130101; C10N
2040/30 20130101; F25B 31/002 20130101 |
International
Class: |
C09K 5/04 20060101
C09K005/04; F25B 31/00 20060101 F25B031/00; F25B 45/00 20060101
F25B045/00; C10M 171/00 20060101 C10M171/00 |
Claims
1. A method for selecting a refrigerant and lubricant for a
vapor-compression refrigeration device system comprising: a.
determining a lower operating temperature range of a
vapor-compression refrigeration device; b. determining an upper
operating temperature range of the vapor-compression refrigeration
device; and c. selecting a refrigerant comprising at least one
C.sub.2 to C.sub.5 fluoroalkene at a first concentration and
selecting a lubricant comprising at least one polyol ester,
polyalkylene glycol, or polyalkylene glycol ester at a second
concentration to produce a fluid system having a refrigerant-rich
phase and a lubricant-rich phase at a first temperature within said
lower operating temperature range and at a second temperature
within said upper operating temperature range provided that said
second temperature is higher than said first temperature, wherein
the refrigerant-rich phase is denser relative to the lubricant-rich
phase at said first temperature and wherein the lubricant-rich
phase is denser relative to the refrigerant-rich phase at said
second temperature, provided that the relative difference in
densities between the two phases is less than 20% at said first
temperature and less than 20% at said second temperature.
2. The method of claim 1 wherein said refrigerant-rich phase and
said lubricant-rich phase are liquid and are substantially
immiscible with each other at said first and second
temperatures.
3. The method of claim 1 wherein said refrigerant has a density
within a range of about 0.8 g/cm.sup.3 to about 1.2 g/cm.sup.3 when
measured at a temperature within a range of about 25.degree. C. to
about 50.degree. C. and wherein said lubricant has a density within
a range of about 0.7 g/cm.sup.3 to about 1.0 g/cm.sup.3 when
measured at a temperature within a range of about 25.degree. C. to
about 50.degree. C.
4. The method of claim 1 wherein the fluoroalkene is a C.sub.3 or
C.sub.4 fluoroalkene.
5. The method of claim 1 wherein the fluoroalkene has a formula
XCF.sub.zR.sub.3-z wherein X is a substituted or unsubstituted
vinyl or allyl radical, R is independently Cl, Br, I or H, and z is
1 to 3.
6. The method of claim 5 wherein z is 3.
7. The method of claim 1 wherein the fluoroalkene is selected from
the group consisting of trifluorpropene, tetrafluoropropene, and
pentafluoropropene.
8. The method of claim 1 wherein the fluoroalkene is selected from
the group consisting of cis-1,3,3,3-tetrafluoropropene;
trans-1,3,3,3-tetrafluoropropene; 1,1,1,2-tetrafluoropropene;
1,1,1-trifluoro-3-chloro-2-propene; 3,3,3-trifluoropropene; and
combinations thereof.
9. The method of claim 1 wherein said polyalkylene glycol is a
branched or straight chain polymer having from about 5 to about 50
units of oxyethylene, oxypropylene, oxybutylene, oxypentylene, or
combinations thereof.
10. The method of claim 9 wherein said polymer comprises at least
50 weight percent oxypropylene units.
11. The method of claim 1 wherein said polyol ester has a structure
according to formulae I or II: RO(R.sup.1O).sub.nC(O)R.sup.2 (I)
R.sup.3(O)C(O)R.sup.2 (II) wherein R is a hydrocarbyl group having
at least 2 carbon atoms, R.sup.1 is a hydrocarbylene group, R.sup.2
is H, hydrocarbyl, --CF.sub.3, --R.sup.4CN, --R.sup.4NO.sup.2 or
R.sup.5OCH(R.sup.6)--, R.sup.3 is a --R.sup.4CF.sup.3, --R.sup.4CN
or --R.sup.4NO.sub.2 group, provided that R.sup.3 may be a
hydrocarbyl group when R.sup.2 is --R.sub.4CN, n is an integer from
1 to about 50, R.sup.4 is a hydrocarbylene group, R.sup.5 is H, a
lower hydrocarbyl group or R.sup.7C(O)-- where R.sup.7 is a
hydrocarbyl group, and R.sup.6 is H or a lower hydrocarbyl
group.
12. The method of claim 1 wherein the relative difference in
densities between the two phases is less than 10% at said first
temperature and less than 10% at said second temperature.
13. The method of claim 1 wherein the relative difference in
densities between the two phases is less than 5% at said first
temperature and less than 5% at said second temperature.
14. The method of claim 1 wherein said higher operating temperature
range is about +30.degree. C. to about +75.degree. C. and said
lower operating temperature range is about -40.degree. C. to about
+25.degree. C.
15. The method of claim 1 wherein said higher operating temperature
range is about +40.degree. C. to about +50.degree. C. and said
lower operating temperature range is selected from the group
consisting of: about -40.degree. C. to about -5.degree. C.,
-20.degree. C. to about 5.degree. C., and about 0.degree. C. to
about 15.degree. C.
16. The method of claim 1 wherein fluid system comprises from about
60 to about 90 weight percent refrigerant and from about 10 to
about 40 weight percent lubricant, wherein weight percents are
relative to the total weight of said fluid system.
17. The method of claim 1 wherein fluid system comprises from about
70 to about 99 weight percent refrigerant and from about 1 to about
30 weight percent lubricant, wherein weight percents are relative
to the total weight of said fluid system.
18. The method of claim 1 wherein said fluid system further
comprises one or more of extreme pressure additives, anti-wear
additives, oxidation stabilizers, thermal stabilizers, pour and
floc point depressants, anti-foaming agents, lubricants soluble in
fluoroolefins, mineral oils, alkylbenzenes, polyalpha-olefins,
alkylated naphthalenes, polyalkylene glycol esters, surfactants,
compatibilizers, and solubilizing agents.
19. A method for introducing a refrigerant and lubricant into a
vapor-compression refrigeration device system comprising: a.
providing a vapor-compression refrigeration device comprising a
heat transfer circuit, a compressor having an inlet side and an
outlet side, and refrigerant and lubricant reservoir, wherein said
reservoir is in fluid communication with the inlet side of the
compressor and with said heat transfer circuit, and said heat
transfer circuit is in fluid communication with said outlet side of
the compressor; b. determining the lower operating temperature
range of the vapor-compression refrigeration device; c. determining
the upper operating temperature range of the vapor-compression
refrigeration device; d. selecting a refrigerant comprising at
least one C.sub.2 to C.sub.5 fluoroalkene at a first concentration
and selecting a lubricant comprising at least one polyol ester or
polyalkylene glycol at a second concentration to produce a fluid
system having a refrigerant-rich phase and a lubricant-rich phase
at a first temperature within said lower operating temperature
range and at a second temperature within said upper operating
temperature range provided that said second temperature is higher
than said first temperature, wherein the refrigerant-rich phase is
denser relative to the lubricant-rich phase at said first
temperature and wherein the lubricant-rich phase is denser relative
to the refrigerant-rich phase at said second temperature; and e.
introducing said refrigerant and lubricant into the
vapor-compression refrigeration device.
20. A method for lubricating a vapor-compression refrigeration
device system comprising: a. providing a vapor-compression
refrigeration device comprising a heat transfer circuit, a
compressor having an inlet side and an outlet side, and refrigerant
and lubricant reservoir, wherein said reservoir is in fluid
communication with the inlet side of the compressor and with said
heat transfer circuit, and said heat transfer circuit is in fluid
communication with said outlet side of the compressor; b.
determining the lower operating temperature range of the
vapor-compression refrigeration device; c. determining the upper
operating temperature range of the vapor-compression refrigeration
device; d. selecting a refrigerant comprising at least one C.sub.2
to C.sub.5 fluoroalkene at a first concentration and selecting a
lubricant comprising at least one polyol ester or polyalkylene
glycol at a second concentration to produce a fluid system having a
refrigerant-rich phase and a lubricant-rich phase at a first
temperature within said lower operating temperature range and at a
second temperature within said upper operating temperature range
provided that said second temperature is higher than said first
temperature, wherein the refrigerant-rich phase is denser relative
to the lubricant-rich phase at said first temperature and wherein
the lubricant-rich phase is denser relative to the refrigerant-rich
phase at said second temperature; e. introducing said refrigerant
and lubricant into the vapor-compression refrigeration device at
said first temperature; and f. lubricating said vapor-compression
refrigeration device with said lubricant, wherein said lubricating
involves increasing the temperature of the vapor-compression
refrigeration device to produce an inversion of the refrigerant and
lubricant-rich phases.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Division of U.S. application Ser. No.
14/261,882, filed Apr. 25, 2014, which application is a
Continuation of U.S. application Ser. No. 13/666,166, filed Nov. 1,
2012, (now U.S. Pat. No. 8,739,559, filed Jun. 3, 2014), which is a
Divisional of U.S. application Ser. No. 12/416,734, filed Apr. 1,
2009 (now U.S. Pat. No. 8,322,149), which claims the priority
benefit of U.S. Provisional Application No. 61/041,474, filed Apr.
1, 2008, and U.S. Provisional Application No. 61/043,486, filed
Apr. 9, 2008, each of which are incorporated herein by reference in
their entirety.
BACKGROUND
[0002] 1. Field of Invention
[0003] The present invention relates to methods for selecting
lubricants used in heat pumps. More particularly, the invention
relates to methods used to select lubricants and hydrofluoroolefins
refrigerant combinations for use in compressor-type heat pumps.
[0004] 2. Description of Prior Art
[0005] The use of chlorine-containing refrigerants, such as
chlorofluorocarbons (CFC's) and hydrochlorofluorocarbons (HCFC's),
in a compression-type refrigeration device (e.g., heat pumps, air
conditioners, refrigerators, and the like) is disfavored because
these refrigerants can damage the Earth's ozone if they leak or are
otherwise discharged from the device. Accordingly, it is desirable
to retrofit chlorine-containing refrigeration systems by replacing
chlorine-containing refrigerants with non-chlorine-containing
refrigerant compounds that will not deplete the ozone layer, such
as hydrofluoroalkanes (HFCs) or hydrofluoroolefins (HFOs). Of
these, HFOs are more desirable because they are typically
characterized as having a much lower Global Warming Potential
(GWP).
[0006] Preferably, these replacement refrigerants are compatible
(e.g., miscible) with conventional compression-type refrigeration
device lubricants. Such compatibility allows lubricant to flow more
easily with the refrigerant throughout the system thereby
increasing the system's efficiency and expected life span. The lack
of compatibility can result in separation of the refrigerant and
lubricant into different phases. If phase separation occurs between
the refrigerant and lubricant while the refrigerator is running, it
affects the life and efficiency of the apparatus seriously. For
example, if phase separation of the refrigerant and the lubricating
oil occurs in the compressor, the moving parts would be
inadequately lubricated, resulting in seizure or other troubles and
thereby the life of apparatus is shortened considerably. If phase
separation occurs in the evaporator, a lubricating oil having high
viscosity exists and thereby the efficiency of heat exchange is
decreased. Unfortunately, many non-chlorine-containing
refrigeration fluids, including HFCs and HFOs, are relatively
insoluble and/or immiscible in conventional lubricants, including,
for example, mineral oils, alkylbenzenes or polyalpha-olefins. In
order for a refrigeration fluid-lubricant combination to work
efficiently within a compression refrigeration, air-conditioning or
heat pump system, the lubricant is preferably compatible with a
refrigerant over a wide range of operating temperatures.
[0007] Generally, a compression-type refrigeration device is
composed of a compressor, a condenser, expansion valve, and an
evaporator, having a mechanism wherein the mixture of a refrigerant
and a lubricating oil is circulating in the closed system. In said
compression-type refrigeration device, though it depends on the
kind of apparatus, generally the temperature in the compressor
rises to about 50.degree. C. or higher, while in the cooler, the
temperature comes to be about -40.degree. C. Accordingly, the
refrigerant and the lubricating oil must circulate in this system
without phase separation usually in the range of about -40 to
+50.degree. C. (See, e.g., U.S. Pat. No. 5,536,881, which is
incorporated herein by reference.)
[0008] Accordingly, the selection of a lubricant for a
compression-type refrigeration device should include an analysis of
the lubricant's miscibility with the desired refrigerant. Achieving
miscibility reduces the need for an oil separator, which can be
installed immediately after the compressor to capture immiscible
oil and return it to the compressor to maintain a desired level of
lubrication. Maintaining good lubrication reduces problems
associated with low oil return, including fouling of the heat
exchanger surfaces and burn-out of the compressor. However, as
noted above, many desirable HFC and HFO refrigerant are immiscible
in conventional lubricants at room temperature. Although various
mixtures of HFO and lubricants are known (see, e.g., US Patent
Application Publication No. 2004/00898, which is incorporated
herein by reference in its entirety), there remains a need for a
method of selecting a lubricant that is compatible with HFC, and
particularly HFO, refrigerants.
SUMMARY OF THE INVENTION
[0009] It has been surprisingly found that certain
refrigerant/lubricant combinations used in compression-type
refrigeration devices did not result in oil return problems,
despite the lack of miscibility between the refrigerant and
lubricant. For example, a fluid system comprising certain HFO
refrigerants and certain lubricants have been found to exhibit a
miscible-type property during the operation of a compression-type
refrigeration devices even though the refrigerant and lubricant
form two phases at the upper operating temperature of the device
and also at lower operating temperatures.
[0010] As used herein, the term "upper operating temperature" means
the temperature of the refrigerant at the outlet of the condenser
during normal device operation and is generally between about
+30.degree. C. and about +75.degree. C., and preferably about
+40.degree. C. to about +50.degree. C. The term "lower operating
temperature" means the temperature of the refrigerant at the outlet
of the expansion value during normal device operation and is
generally between about -40.degree. C. to about +25.degree. C. In
certain preferred embodiments, particularly for embodiments wherein
the device is refrigeration equipment, the lower operating
temperature is in a range of -40 to -5.degree. C. In certain other
preferred embodiments, particularly for embodiments wherein the
device is a refrigerator or heat pump, the lower operating
temperature is in a range of about -20 to +5.degree. C. In certain
other preferred embodiments, particularly for embodiments wherein
the device is an air conditioner, the lower operating temperature
is in a range of about 0 to +15.degree. C.
[0011] As used herein, the term "phase" means a compositional
region of a fluid system that is substantially chemically uniform
and physically distinct. The phase size may be microscopic or, more
preferably, macroscopic.
[0012] The term "lubricant" means a substance that when disposed
between two moving surfaces, tends to reduce the friction between
the surfaces, thereby improving efficiency and reducing wear.
Lubricants may optionally have the function of dissolving and/or
transporting foreign particles in a device.
[0013] The term "refrigerant" means one or more compounds that
undergo a phase change from a gas to a liquid and back in a
conventional compression-type refrigeration device to effectively
transfer heat to or from an environment.
[0014] The term "lubricant-rich phase" means a phase in a fluid
system comprising a majority of lubricant relative to refrigerant
(i.e., more than about 50 weight % and less than 100 weight %). In
certain embodiments, the lubricant-rich phase comprises from about
10 to about 90 wt. % lubricant relative to refrigerant, more
preferably about 25 to about 70 wt. %, and even more preferably
about 40 to about 60 wt %.
[0015] The term "refrigerant-rich phase" means a phase in a fluid
system comprising a majority of refrigerant (i.e., more than about
50 weight % and less than 100 weight %), preferably at least about
75 wt. % to less than 100 wt. % refrigerant relative to lubricant,
and more preferably at least about 90 to about 98 wt. % refrigerant
relative to lubricant.
[0016] With respect to a fluid system comprising a refrigerant-rich
phase and a lubricant-rich phase, inversion of the phases occurs as
the density of each phase inversely changes with respect to a
change in temperature, i.e., a first phase that is more dense with
respect to a second phase at one temperature changes to become less
dense compared to the second phase as a different temperature. More
particularly, at relatively low temperatures, the refrigerant-rich
phase is denser than the lubricant-rich phase and, accordingly,
settles to the bottom of the fluid system. As the temperature
rises, the lubricant-rich phase becomes heavier and sinks to the
bottom. This phase inversion is believed to produce the
miscible-type characteristic observed in the fluid system.
Lubricant return to the compressor is therefore improved.
[0017] Accordingly, an aspect of the invention is a method for
selecting a refrigerant and lubricant for a vapor-compression
refrigeration device system comprising the steps of: (a)
determining a lower operating temperature range of a
vapor-compression refrigeration device; (b) determining an upper
operating temperature range of the vapor-compression refrigeration
device; and (c) selecting a refrigerant comprising at least one
C.sub.2 to C.sub.5 fluoroalkene at a first concentration and
selecting a lubricant comprising at least one polyol ester,
polyalkylene glycol, or polyalkylene glycol ester at a second
concentration to produce a fluid system having a refrigerant-rich
phase and a lubricant-rich phase at a first temperature within said
lower operating temperature range and at a second temperature
within said upper operating temperature range provided that said
second temperature is higher than said first temperature, wherein
the refrigerant-rich phase is denser relative to the lubricant-rich
phase at said first temperature and wherein the lubricant-rich
phase is denser relative to the refrigerant-rich phase at said
second temperature, provided that the relative difference in
densities between the two phases is less than 20% at said first
temperature and less than 20% at said second temperature.
[0018] In another aspect of the invention, provided is a method for
introducing a refrigerant and lubricant into a vapor-compression
refrigeration device system comprising the steps of: (a) providing
a vapor-compression refrigeration device comprising a heat transfer
circuit, a compressor having an inlet side and an outlet side, and
refrigerant and lubricant reservoir, wherein said reservoir is in
fluid communication with the inlet side of the compressor and with
said heat transfer circuit, and said heat transfer circuit is in
fluid communication with said outlet side of the compressor; (b)
determining the lower operating temperature range of the
vapor-compression refrigeration device; (c) determining the upper
operating temperature range of the vapor-compression refrigeration
device; (d) selecting a refrigerant comprising at least one C.sub.2
to C.sub.5 fluoroalkene at a first concentration and selecting a
lubricant comprising at least one polyol ester or polyalkylene
glycol at a second concentration to produce a fluid system having a
refrigerant-rich phase and a lubricant-rich phase at a first
temperature within said lower operating temperature range and at a
second temperature within said upper operating temperature range
provided that said second temperature is higher than said first
temperature, wherein the refrigerant-rich phase is denser relative
to the lubricant-rich phase at said first temperature and wherein
the lubricant-rich phase is denser relative to the refrigerant-rich
phase at said second temperature; and (e) introducing said
refrigerant and lubricant into the vapor-compression refrigeration
device.
[0019] In yet another aspect of the invention, provided is a method
for lubricating a vapor-compression refrigeration device system
comprising the steps of: (a) providing a vapor-compression
refrigeration device comprising a heat transfer circuit, a
compressor having an inlet side and an outlet side, and refrigerant
and lubricant reservoir, wherein said reservoir is in fluid
communication with the inlet side of the compressor and with said
heat transfer circuit, and said heat transfer circuit is in fluid
communication with said outlet side of the compressor; (b)
determining the lower operating temperature range of the
vapor-compression refrigeration device; (c) determining the upper
operating temperature range of the vapor-compression refrigeration
device; (d) selecting a refrigerant comprising at least one C.sub.2
to C.sub.5 fluoroalkene at a first concentration and selecting a
lubricant comprising at least one polyol ester or polyalkylene
glycol at a second concentration to produce a fluid system having a
refrigerant-rich phase and a lubricant-rich phase at a first
temperature within said lower operating temperature range and at a
second temperature within said upper operating temperature range
provided that said second temperature is higher than said first
temperature, wherein the refrigerant-rich phase is denser relative
to the lubricant-rich phase at said first temperature and wherein
the lubricant-rich phase is denser relative to the refrigerant-rich
phase at said second temperature; (e) introducing said refrigerant
and lubricant into the vapor-compression refrigeration device at
said first temperature; and (f) lubricating said vapor-compression
refrigeration device with said lubricant, wherein said lubricating
involves increasing the temperature of the vapor-compression
refrigeration device to produce an inversion of the refrigerant and
lubricant-rich phases.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows a graph of the density of the polyalkylene
glycol lubricant ND 8 oil with HFO-1234yf.
[0021] FIG. 2 shows a graph of the density of the polyalkylene
glycol lubricant Idemitsu PAG 46PS with HFO-1234yf.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
[0022] Preferred embodiments of the invention involve the selection
of a fluoroalkene refrigerant and a lubricant which, when combined,
produce a fluid system having a miscible-type property. Such a
fluid system is useful in the operation of vapor-compression
refrigeration device.
[0023] Useful refrigerants preferably comprises at least one
C.sub.2 to C.sub.5 fluoroalkene, and more preferably a C.sub.3 to
C.sub.4 fluoroalkene. Preferred fluoroalkenes are those having the
formula: XCF.sub.zR.sub.3-z wherein X is a substituted or
unsubstituted vinyl or allyl radical, R is independently Cl, Br, I
or H, and z is 1 to 3, preferably 3. Particularly preferred
fluoroalkanes include trifluorpropenes, tetrafluoropropenes, and
pentafluoropropenes. Examples of preferred isomers of these
compounds include cis-1,3,3,3-tetrafluoropropene;
trans-1,3,3,3-tetrafluoropropene; 1,1,1,2-tetrafluoropropene;
1,1,1-trifluoro-3-chloro-2-propene; and 3,3,3-trifluoropropene. The
refrigerant can include one of these compounds of some combination
thereof.
[0024] Useful lubricants include polyol ester and polyalkylene
glycols. The polyalkylene glycol lubricants suitable for use with
the present invention typically contain from about 5 to 50
oxylakylene repeating units that have from 1 to 5 carbon atoms. The
polyalkylene glycol can be straight chain or branched and can be a
homopolymer or co-polymer of 2, 3 or more oxyethylene,
oxypropylene, oxybutylene or oxypentylene groups or combinations
thereof in any proportions. Preferred polyalkylene glycols contain
at least 50% oxypropylene groups. Compositions according to the
present invention may contain one or more polyalkylene glycols as
the lubricant, one or more polyalkylene glycol esters as the
lubricant, one or more polyol esters as the lubricant, or a mixture
of one of more polyalkylene glycols, one or more polyalkylene
glycol esters and one or more polyol esters. Vinyl ethers are also
useful in this invention.
[0025] Useful polyalkylene glycols are described in U.S. Pat. Nos.
4,971,712; 4,948,525 and 5,254,280, and 4,755,316, the printed
specifications of which are incorporated herein by reference. While
suitable polyalkylene glycols include glycols terminating at each
end with a hydroxyl group, other suitable lubricants include
polyalkylene glycols in which either or both terminal hydroxyl
group is capped. The hydroxyl group may be capped with alkyl groups
containing from 1 to 10 carbon atoms, 1 to 10 carbon atom alkyl
groups containing heteroatoms such as nitrogen, the fluoroalkyl
groups described by U.S. Pat. No. 4,975,212, the printed
specification of which is incorporated herein by reference. When
both polyalkylene glycol hydroxyl groups are end capped, the same
type or a combination of two different types of terminal capping
groups can be used. Either or both hydroxyl groups can also be
capped by forming the ester thereof with a carboxylic acid as
disclosed by U.S. Pat. No. 5,008,028, the specification of which is
also incorporated herein by reference.
[0026] The carboxylic acid can also be fluorinated. When both ends
of the polyalkylene glycol are capped, either or both ends may be
capped with an ester, or one end may be capped with an ester and
the other not capped or capped with one of the aforementioned
alkyl, heteroalkyl or fluoroalkyl groups.
[0027] Commercially available polyalkylene glycol lubricants
include Goodwrench Refrigeration Oil for General Motors and
MOPAR-56 from Daimler-Chrysler, which is a polyalkylene glycol that
is bis-capped by acetyl groups. A wide variety of polyalkylene
glycol lubricants are also available from Dow Chemical or Shrieve
Chemical Products. Commercially available polyol esters include
Mobil EAL Arctic 22CC available from Exxon-Mobil and Solest 120
available from CPI Engineering Services, Inc.
[0028] Preferred polyol esters have a structure according to
formulae (I) or (II):
RO(R.sup.1O).sub.nC(O)R.sup.2 (Formula I)
R.sup.3(O)C(O)R.sup.2 (Formula II)
wherein R is a hydrocarbyl group having at least 2 carbon atoms,
R.sup.1 is a hydrocarbylene group, R.sup.2 is H, hydrocarbyl,
--CF.sub.3, --R.sup.4CN, --R.sup.4NO.sup.2 or
R.sup.5OCH(R.sup.6)--, R.sup.3 is a --R.sup.4CF.sup.3, --R.sup.4CN
or --R.sup.4NO.sub.2 group, provided that R.sup.3 may be a
hydrocarbyl group when R.sup.2 is --R.sub.4CN, n is an integer from
1 to about 50, R.sup.4 is a hydrocarbylene group, R.sup.5 is H, a
lower hydrocarbyl group or R.sup.7C(O)-- where R.sup.7 is a
hydrocarbyl group, and R.sup.6 is H or a lower hydrocarbyl
group.
[0029] These are more fully described in U.S. Pat. No. 5,008,028,
the printed specification of which is incorporated herein by
reference. Preferably the fluoroalkene and the lubricant are
substantially immiscible with one another.
[0030] The lubricants of this invention typically have a density of
when measured at a temperature of from about 25.degree. C. to about
50.degree. C. ranging from about 0.7 g/cm.sup.3 to about 1.2
g/cm.sup.3; preferably from about 0.9 g/cm.sup.3 to about 1
g/cm.sup.3; and more preferably from about 0.95 g/cm.sup.3 to about
1 g/cm.sup.3.
[0031] The fluoroalkenes of this invention typically have a density
of when measured at a temperature of from about 25.degree. C. to
about 50.degree. C. ranging from about from about 0.8 g/cm.sup.3 to
about 1.4 g/cm.sup.3; preferably from about 0.99 g/cm.sup.3 to
about 1.09 g/cm.sup.3; and more preferably from about 1.04
g/cm.sup.3 to about 1.19 g/cm.sup.3.
[0032] In a typical automobile refrigeration system, the
fluoroalkene may be present in an amount of from about 60 to about
90 weight percent, preferably from about 65 to about 80 weight
percent based on the weight of the total refrigerant and lubricant
charge.
[0033] In a typical automobile refrigeration system, the lubricant
may be present in an amount of from about 10 to about 40 weight
percent, preferably from about 20 to about 35 weight percent based
on the weight of the total refrigerant and lubricant charge.
[0034] In a typical stationary refrigeration system, the
fluoroalkene may be present in an amount of from about 70 to about
99 weight percent, preferably from about 80 to about 85 weight
percent based on the weight of the total refrigerant and lubricant
charge.
[0035] In a typical stationary refrigeration system, the lubricant
may be present in an amount of from about 1 to about 30 weight
percent, preferably from about 15 to about 20 weight percent based
on the weight of the overall total refrigerant and lubricant
charge.
[0036] In preferred embodiments, the refrigerant-lubricant mixture
compositions of this invention may have viscosities of from about 1
to 1000 centistokes at about 37.degree. C., more preferably in the
range of from about 2 to about 200 centistokes at about 37.degree.
C. and even more preferably of from about 4 to about 40 centistokes
at about 37.degree. C.
[0037] In addition to the HFO refrigerant and lubricant,
compositions according to the present invention can include other
additives or materials of the type used in refrigeration,
air-conditioning and heat pump compositions to enhance their
performance. For example, the compositions can also include extreme
pressure and anti-wear additives, oxidation and thermal stability
improvers, pour and floc point depressants, anti-foaming agents,
other lubricants soluble and insoluble in HFO's, and the like.
Examples of such additives are disclosed in U.S. Pat. No.
5,254,280, the printed specification of which is incorporated
herein by reference
[0038] Compositions of the present invention can thus further
include a quantity of mineral oil, alkyl benzene, polyalpha-olefin
or alkylated naphthalene lubricants or combinations thereof that
would not otherwise be miscible or soluble with the HFO but is at
least partially miscible or partially soluble when added to the HFO
in combination with a polyalkylene glycol, polyalkylene glycol
ester or polyol ester. Typically, this is a quantity up to about
5-20 weight %, however in some embodiments may range up to 90
weight %. A surfactant may also be added to compatibilize the
mineral oil with the polyalkylene glycol, polyalkylene glycol ester
or polyol ester and the HFO, as disclosed in U.S. Pat. No.
6,516,837, the disclosure of which is incorporated herein by
reference.
[0039] The compositions of the present invention may include other
components for the purpose of enhancing or providing certain
functionality to the composition, or in some cases to reduce the
cost of the composition. For example, the present compositions may
also include a compatibilizer, such as propane, for the purpose of
aiding compatibility and/or solubility of the lubricant. 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 stabilizer, 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.
[0040] The composition of this invention may optionally include
alkylbenzenes, or hydrocarbon based lubricants in amounts of from 0
to about 30 weight percent.
[0041] The fluoroalkene and lubricant forms an immiscible
composition having two or more distinct phases, preferably having a
distinct interface which can be determined either visually or by
refractometry. Provided that the density of each phase is close to
that of the other, the fluids can be easily kept in circulation in
the compression-type refrigeration device. Preferably, the
composition has a refrigerant-rich phase and one or more
lubricant-rich phases wherein the difference in density between the
refrigerant-rich phase and the lubricant-rich phase is about 20% or
less, preferably about 10% or less, and more preferably about 5% or
less.
[0042] At temperatures below the "phase inversion temperature" the
lubricant-rich phase is on top of the refrigerant-rich phase and at
temperatures above the "phase inversion temperature" the
refrigerant-rich phase is on top of the lubricant-rich phase. The
temperature at which a particular composition flips from one phase
on top to the other phase on top is the phase inversion
temperature. Usually for temperatures less than the phase inversion
temperature a majority of lubricant floats on top of the
refrigerant-rich phase before the circulation is started. For a
temperature near the phase inversion temperature, stable emulsions
are produced at all flow rates and once produced, the equilibrium
phase separation time is very long, on the order several hours for
complete separation. For temperatures greater than the phase
inversion temperature, the lubricant-rich phase is present at the
bottom of reservoirs, and once flow has begun, a stable emulsion is
created. For vessels or components where the withdrawal piping is
located at the bottom, at temperatures greater than the phase
inversion temperature, circulation rates higher than the charged
composition indicate that conglomeration of lubricant-rich phase
sinks to the bottom of the reservoir where it is drawn again into
circulation. This emulsion and phase inversion temperature behavior
allows the reliable operation of the compression-type refrigeration
device. That is, the composition is in a form wherein either the
refrigerant-rich phase is positioned on the lubricant-rich phase or
the lubricant-rich phase is positioned on the refrigerant-rich
phase, and a temperature exists at which the positions of the
refrigerant-rich phase and the lubricant-rich phase reverse
positions relative to one another. Such phase inversion
temperatures may range from about -15.degree. C. to about
75.degree. C., preferably from about 10.degree. C. to about
60.degree. C., and more preferably from about 20.degree. C. to
about 50.degree. C.
[0043] Any of a wide range of methods for introducing the
refrigeration compositions of the present invention to a
compression refrigeration, air-conditioning or heat pump system can
be used from the present invention. For example, one method
comprises attaching a refrigerant container to the low-pressure
side of a refrigeration system and turning on the refrigeration
system compressor to pull the refrigeration composition into the
system. In such embodiments, the refrigerant container may be
placed on a scale such that the amount of refrigeration composition
entering the system can be monitored. When a desired amount of
refrigeration composition has been introduced into the system,
charging is stopped. Alternatively, a wide range of charging tools,
known to those skilled in the art, are commercially available.
Accordingly, in light of the above disclosure, those of skill in
the art will be readily able to introduce the HFO refrigerant and
refrigeration compositions of the present invention into
compression refrigeration, air-conditioning and heat pump systems
without undue experimentation.
Example 1
[0044] A calorimetric performance test system using a full
automotive air conditioning system utilizing production heat
exchangers, lines and compressor was run using PAG RL897 as
lubricant and HFO-1234yf as refrigerant. There were no oil return
problems. This was because of the surprising emulsion like behavior
of the refrigerant/oil mixture. This is due in part to the
similarity in density as shown by the inversion in density.
Example 2
[0045] A circulation loop was constructed to investigate the charge
concentration of the loop compared to the circulating composition
at various temperatures for an Idemitsu PAG 46PS/HFO-1234yf
mixture. The apparatus was constructed such that a large reservoir
was drained slowly from the bottom and the liquid was pumped and
returned to the top of the reservoir. The pumping rates were
regulated to traditional automotive system refrigerant flow rates
from 5 to 60 g/sec and the large reservoir was used to simulate an
worse case high pressure side liquid receiver. The results are
shown in Table 1. For temperatures less than the phase inversion
temperature (34.degree. C.) the lubricant-rich phase floats on top
of the refrigerant-rich phase before the circulation is started.
For flows greater than 15 g/sec, the turbulence in the reservoir is
high enough to create a stable emulsion and the circulation
concentration is the same as the charged concentration; while even
for low flow, the circulating flow still contains a very large
percentage of the charged lubricant as the static equilibrium
separation concentration is approximately 4%, but a small amount of
lubricant rich phase is still present at the surface. For a
temperature near the phase inversion temperature, stable emulsions
are produced at all flow rates and once produced, the static
equilibrium separation time is very long, on the order several
hours. For temperatures greater than the phase inversion
temperature, the lubricant-rich phase is present at the bottom of
the reservoir, and once flow has begun, a stable emulsion is
created. The circulation rates higher than the charged composition
indicated that conglomeration of lubricant-rich phase sinks to the
bottom of the reservoir where it is drawn again into circulation,
and is indicative of the experimental setup, whereas in an
operating heat pump, AC or refrigeration system the oil that
travels into a high pressure liquid receiver will flow through and
out of the withdrawal piping and will not be logged vessels or
manifolds.
TABLE-US-00001 TABLE 1 Circulation Rates for Bottom draw of
HFO-1234yf and Idemitsu PAG 46 PS Temperature Temperature
Temperature 20.degree. C. 35.degree. C. 45.degree. C. Min. Flow
Charged: 10.7% Charged: 10.8% Charged: 10.8% Rate Circulating: 8.9%
Circulating: 16.3% Circulating: 47.4% 5 g/sec. Avg. Flow Charged:
10.7% Charged: 10.7% Charged: 10.8% Rate Circulating: Circulating:
11.9% Circulating: 18.8% 30 g/sec. 10.8% Max. Charged: 10.6%
Charged: 10.4% Charged: 10.3% Flow Circulating: Circulating: 11.0%
Circulating: 19.5% Rate 10.9% 50 g/sec.
[0046] Phase inversion and immiscibility has also been measured
with polyol ester lubricants at temperatures approximately
equivalent to polyalkylene lubricants. Alkylbenzene, mineral oils,
polyalpha-olefins and alkylated naphthalenes have phase inversion
temperatures greater than 70.degree. C. which limits their
application in air conditioning, residential heat pump and
refrigeration equipment; however, these mixtures could have
application in high temperature heat pump applications. The
mixtures of hydrocarbon lubricants such as alkylbenzene, mineral
oil, polyalpha-olefin and alkylated naphthalenes with polyol ester
have phase inversion temperatures between the POE-HFO mixture and
the hydrocarbon lubricant --HFO mixture temperature depending on
the POE-hydrocarbon lubricant blending ratio.
Example 3
[0047] FIGS. 1 and 2 show the densities of constant concentrations
of HFO-1234yf with two different polyalkylene glycol lubricants,
Denso ND 8 oil and Idemitsu PAG 46 PS, respectively. While the ND 8
oil and the 46PS lubricants are similar in type classification and
viscosity grade, the base molecules for which the final lubricant
product is constructed are different. The density curves were
experimentally determined by mixing a constant weight percentage of
HFO-1234yf with lubricant and measuring the mixture liquid density
over the range of temperatures from 0.degree. C. to 150.degree. C.
This was repeated for each lubricant--refrigerant ratio progressing
from pure lubricant up to 50% HFO-1234yf. For both lubricants at
the 50% refrigerant-lubricant blend, the liquid solution becomes
immiscible and splits into fluoroalkene rich and fluoroalkene lean
phases. This concentration and for concentrations greater than 50%
fluoroalkene this mixture exhibits a density phase inversion where
the fluoroalkene rich phase becomes lighter than the fluoroalkene
lean phase upon heating. This phase inversion occurs at
approximately 35.degree. C. for the Denso ND 8 oil, while the
Idemitsu PAG 46PS lubricant exhibits a density inversion
temperature from approximately 25.degree. C. and 35.degree. C. that
varies slightly as the refrigerant lean phase concentration
varies.
Prophetic Examples 4-18
[0048] The procedure of Example 3 is repeated with the following
refrigerant-oil mixtures which produced acceptable results.
Example 4--cis-1,3,3,3-tetrafluoropropene/PAG Example
5--trans-1,3,3,3-tetrafluoropropene/PAG Example
6--1,1,1,2-tetrafluoropropene/PAG Example
7--1,1,1-trifluoro-3-chloro-2-propene/PAG Example
8--3,3,3-trifluoropropene/PAG Example
9--cis-1,3,3,3-tetrafluoropropene/PEG Example
10--trans-1,3,3,3-tetrafluoropropene/PEG Example
11--1,1,1,2-tetrafluoropropene/PEG Example
12--1,1,1-trifluoro-3-chloro-2-propene/PEG Example
13--3,3,3-trifluoropropene/PEG Example
14--cis-1,3,3,3-tetrafluoropropene/POE Example
15--trans-1,3,3,3-tetrafluoropropene/POE Example
16--1,1,1,2-tetrafluoropropene/POE Example
17--1,1,1-trifluoro-3-chloro-2-propene/POE Example
18--3,3,3-trifluoropropene/POE
[0049] While the present invention has been particularly shown and
described with reference to preferred embodiments, it will be
readily appreciated by those of ordinary skill in the art that
various changes and modifications may be made without departing
from the spirit and scope of the invention. It is intended that the
claims be interpreted to cover the disclosed embodiment, those
alternatives which have been discussed above and all equivalents
thereto.
* * * * *