U.S. patent application number 13/379316 was filed with the patent office on 2012-04-26 for refrigeration circuit and method for improving same.
Invention is credited to Hiromitsu Kamishima, Yuuichi Matsumoto, Tomoaki Matsuzaki.
Application Number | 20120096878 13/379316 |
Document ID | / |
Family ID | 43356172 |
Filed Date | 2012-04-26 |
United States Patent
Application |
20120096878 |
Kind Code |
A1 |
Kamishima; Hiromitsu ; et
al. |
April 26, 2012 |
Refrigeration Circuit and Method for Improving Same
Abstract
Disclosed is a refrigeration circuit in which a scroll
compressor is used as a compressor, an unsaturated fluorinated
hydrocarbon refrigerant is used as a refrigerant, and an
ether-based lubricant such as a polyalkylene glycol is used as a
refrigeration machine oil, and wherein a wax-like solid material,
which causes clogging of the refrigeration circuit or deterioration
of the refrigeration performance, is prevented from being
generated. Specifically, a wax-like solid material is prevented
from being generated in a refrigeration circuit by adding a
lubricant type component having no polyoxyalkylene structure such
as an ester-based lubricant, an alcohol-based friction modifier, an
olefin-based friction modifier, a polyolefin-based lubricant, an
alkyl aromatic lubricant or a silicone-based lubricant, or a metal
deactivation agent such as benzotriazole to an ether-based
lubricant such as a polyalkylene glycol.
Inventors: |
Kamishima; Hiromitsu;
(Gunma, JP) ; Matsuzaki; Tomoaki; (Gunma, JP)
; Matsumoto; Yuuichi; (Gunma, JP) |
Family ID: |
43356172 |
Appl. No.: |
13/379316 |
Filed: |
June 16, 2010 |
PCT Filed: |
June 16, 2010 |
PCT NO: |
PCT/JP2010/003980 |
371 Date: |
December 19, 2011 |
Current U.S.
Class: |
62/84 ;
62/468 |
Current CPC
Class: |
C10N 2020/101 20200501;
C10N 2040/30 20130101; C10M 2205/00 20130101; F25B 2500/04
20130101; C10N 2030/06 20130101; Y02P 30/48 20151101; C10M 2215/22
20130101; C10M 171/008 20130101; C09K 2205/126 20130101; C09K 5/045
20130101; C10M 2207/02 20130101; C10M 2209/1033 20130101; Y02P
30/40 20151101 |
Class at
Publication: |
62/84 ;
62/468 |
International
Class: |
F25B 41/00 20060101
F25B041/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 17, 2009 |
JP |
2009-144077 |
Sep 11, 2009 |
JP |
2009-210258 |
Claims
1. A refrigeration circuit provided with a scroll compressor as a
compressor for compressing a refrigerant, wherein said refrigerant
contains an unsaturated fluorinated hydrocarbon refrigerant as a
part or the whole thereof, a refrigeration machine oil comprises an
ether-based lubricant having a polyoxyalkylene structure, and said
ether-based lubricant contains one or more selected from a
lubricant type component having no polyoxyalkylene structure and a
metal deactivation agent.
2. A method for improving a refrigeration circuit provided with a
scroll compressor as a compressor for compressing a refrigerant,
wherein, by a condition where said refrigerant contains an
unsaturated fluorinated hydrocarbon refrigerant as a part or the
whole thereof, a refrigeration machine oil comprises an ether-based
lubricant having a polyoxyalkylene structure, and said ether-based
lubricant contains one or more selected from a lubricant type
component having no polyoxyalkylene structure and a metal
deactivation agent, decomposition of said unsaturated fluorinated
hydrocarbon refrigerant caused by operation of said compressor and
generation of a polymerized paraffin originating from
polymerization of a polymerizable decomposed substance are
prevented.
3. The refrigeration circuit according to claim 1, wherein said
unsaturated fluorinated hydrocarbon refrigerant is an unsaturated
fluorinated hydrocarbon refrigerant having a group of
CH.sub.2.dbd.CH-- or CH.sub.2.dbd.CF-- at an end of a molecule.
4. The refrigeration circuit according to claim 1, wherein said
unsaturated fluorinated hydrocarbon refrigerant is at least one of
HFO1234yf and HFO1234ze.
5. The refrigeration circuit according to claim 1, wherein said
lubricant type component is an ester-based lubricant.
6. The refrigeration circuit according to claim 1, wherein said
lubricant type component is an ester-based lubricant comprising a
polyol ester derived from a polyol and a univalent aliphatic
acid.
7. The refrigeration circuit according to claim 1, wherein said
lubricant type component is an alcohol-based friction modifier.
8. The refrigeration circuit according to claim 1, wherein said
lubricant type component is an alcohol-based friction modifier
comprising an aliphatic polyol having a carbon number in a range of
2 to 25.
9. The refrigeration circuit according to claim 1, wherein said
lubricant type component is an olefin-based friction modifier.
10. The refrigeration circuit according to claim 1, wherein said
lubricant type component is an olefin-based friction modifier
comprising an olefin having a carbon number in a range of 10 to
18.
11. The refrigeration circuit according to claim 1, wherein said
lubricant type component is a polyolefin-based lubricant comprising
a poly-.alpha.-olefin.
12. The refrigeration circuit according to claim 1, wherein said
lubricant type component is an alkyl aromatic lubricant.
13. The refrigeration circuit according to claim 1, wherein said
lubricant type component is an alkyl aromatic-based lubricant
selected from an alkyl benzene and an alkyl naphthalene.
14. The refrigeration circuit according to claim 1, wherein said
lubricant type component is a silicone-based lubricant.
15. The refrigeration circuit according to claim 1, wherein said
metal deactivation agent is a benzotriazole-based component.
16. The refrigeration circuit according to claim 1, wherein said
ether-based lubricant contains an acid capturing agent.
17. The refrigeration circuit according to claim 1, wherein said
ether-based lubricant contains an epoxy alkane having a carbon
number in a range of 8 to 25 as an acid capturing agent.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a refrigeration circuit in
which refrigerant containing unsaturated fluorinated hydrocarbon
compound typified by HFO-1234yf as a part or the whole thereof is
used, and also relates to a method for improving the refrigeration
circuit.
BACKGROUND ART OF THE INVENTION
[0002] In a refrigeration circuit used in an air conditioning
system for vehicles, etc., HFC134a which is a kind of fluorocarbons
is currently used as a typical refrigerant and polyalkylene glycol
(PAG) is currently used as a typical refrigerating machine oil.
[0003] At present, an approach for the prevention of global warming
is active on a worldwide scale. Particularly in EU countries, in
the F-gas regulation, a regulation on the high global warming
potential (GWP1430) of the typical refrigerant for vehicles HFC134a
has been promoted, and the prohibition of the use of this
refrigerant for a new car from 2012 and the prohibition of the use
of this refrigerant for every car from 2017 have been adopted. As a
result, similar regulations are being spread all over the world.
Corresponding to this trend, refrigerant manufacturers,
refrigerating machine oil manufacturers and air conditioning system
manufacturers are carrying out research and development of a new
refrigerant and a refrigerating machine oil for the new refrigerant
with the aim of further reducing and improving global warming
potential (GWP) while maintaining its safety. Presently, as a new
refrigerant with the aim of such an improvement, various
unsaturated fluorinated hydrocarbon refrigerants having an
evaporation temperature in a range of -50 to -10.degree. C. are
being developed by introducing an unsaturated bond into a molecule
thereof so as to lower its GWP so as to achieve next-generation
refrigerants. In particular, it is likely that unsaturated
fluorinated hydrocarbon refrigerants such as HFO1234yf and
HFO1234ze will be adopted on a global scale. Experimental research
with the objective of an improvement in order to apply these
materials to a refrigeration circuit such as an air conditioning
system for vehicles is becoming active.
SUMMARY OF THE INVENTION
Problems to be solved by the Invention
[0004] Although the unsaturated fluorinated hydrocarbon refrigerant
has low GWP value as one of its features, it has high reactivity,
low thermal stability and low chemical stability relative to a
conventional saturated fluorinated hydrocarbon refrigerant such as
HFC134a since it has an unsaturated bond in a molecule. Inventors
of the present invention carried out an experiment for studying the
thermal and chemical stability of the refrigerant in an actual
refrigeration circuit, and confirmed a fact that, in a
refrigeration circuit of an experimental system using a scroll
compressor as a compressor, HFO1234yf as refrigerant and
polyalkylene glycol as a refrigerating machine oil, a wax-like
solid is generated in the compressor especially under high-speed
and heavy load conditions. On the other hand, in a refrigeration
circuit of an experimental system where a reciprocating compressor
is used instead of the scroll compressor, it found out that a
wax-like solid is not generated even under high-speed and heavy
load conditions. Because this wax-like solid causes a clog of a
refrigeration circuit or deterioration of refrigeration
performance, a critical defect such as significant deterioration of
refrigeration performance or failure of the refrigeration circuit
might be caused. The wax-like solid is supposed to be generated not
only in the case of HFO1234yf, but also in the cases of other
unsaturated fluorinated hydrocarbon refrigerants having a similar
unsaturated bond in a molecule. Thus, if an unsaturated fluorinated
hydrocarbon refrigerant is used in a refrigeration circuit, it is
necessary to prevent such a wax-like solid from being generated in
a compressor and in the refrigeration circuit, especially even
under high-speed and heavy load conditions.
[0005] Therefore, an object of the present invention is to prevent
a wax-like solid, which can be a cause of clogging of the
refrigeration circuit and degradation in refrigeration performance,
from being generated in a refrigeration circuit provided with a
scroll compressor as a compressor, an unsaturated fluorinated
hydrocarbon refrigerant and an ether-based lubricant such as
polyalkylene glycol as refrigeration machine oil.
Means for solving the Problems
[0006] The inventors of the present invention carried out a
chemical analysis of the wax-like solid, and confirmed that this
solid is a polymerized paraffin with a low molecular mass having a
melting point in a range of approximately 50 to 72.degree. C.
According to the result of the analysis, the inventors assume a
generation mechanism for the wax-like solid as described below.
Namely, in a scroll compressor, a refrigerating machine oil used is
required to have high lubricating performance because a scroll
member of a movable scroll and a scroll member of a fixed scroll
come into sliding contact with each other in a state of being
pressed strongly by each other in order to oppose the action of
high-temperature and high-pressure refrigerant gas concurrently
with a rotational movement of the movable scroll. However,
lubricating performance of an ether-based lubricant such as
polyalkylene glycol to a refrigerant having an unsaturated bond
such as HFO1234yf is not quite enough for the scroll compressor.
Thus, under high-temperature and heavy load conditions, active
metal surface is liable to be exposed locally at the sliding
contact surface of the compression mechanism part as accompanying
with the rotational movement of the movable scroll. Meanwhile, an
unsaturated fluorinated hydrocarbon refrigerant has high
reactivity, low thermal stability and low chemical stability. As a
result, presumably, the exposed active metal surface acts as a
reaction catalyst and induces a reaction between the unsaturated
fluorinated hydrocarbon refrigerant and a polyoxyalkylene structure
of the ether-based lubricant under an atmosphere of
high-temperature and high-pressure refrigerant gas in the
compression mechanism part of the scroll compressor, and
accordingly, decomposition of the unsaturated fluorinated
hydrocarbon refrigerant and generation of a polymerizable olefin
which is a decomposed ingredient thereof occur, and further, this
polymerizable olefin polymerizes to form a polymerized paraffin by
the polymerization catalytic activity of the active metal surface
under pressure and heat in the compressor. Therefore, in order to
prevent generation of the wax-like solid, it can be an effective
means to compensate for the insufficiency of lubricating
performance of the ether-based lubricant by combined use of another
lubricant-type component having no polyoxyalkylene structure.
Additionally, it can also be an effective means to prevent the
ether-based lubricant and the unsaturated fluorinated hydrocarbon
refrigerant from coming into contact with this active metal surface
that the exposed active metal surface is deactivated immediately
with a metal deactivation agent. The present invention has been
completed according to such a technical knowledge and idea.
[0007] Namely, a refrigeration circuit according to the present
invention is a refrigeration circuit provided with a scroll
compressor for compressing a refrigerant, characterized in that the
refrigerant contains an unsaturated fluorinated hydrocarbon
refrigerant as a part or the whole thereof, a refrigeration machine
oil comprises an ether-based lubricant having a polyoxyalkylene
structure, and the ether-based lubricant contains one or more
selected from a lubricant type component having no polyoxyalkylene
structure and a metal deactivation agent. According to the present
invention, the lubricant-type component and the metal deactivating
agent function as a polymerized paraffin inhibitor preventing
decomposition of unsaturated fluorinated hydrocarbon refrigerant
caused by operation of the compressor and generation of polymerized
paraffin originating from polymerization of a polymerizable
decomposed substance.
[0008] Further, a method for improving a refrigeration circuit
according to the present invention is a method for improving a
refrigeration circuit provided with a scroll compressor as a
compressor for compressing a refrigerant, characterized in that, by
a condition where the refrigerant contains an unsaturated
fluorinated hydrocarbon refrigerant as a part or the whole thereof,
a refrigeration machine oil comprises an ether-based lubricant
having a polyoxyalkylene structure, and the ether-based lubricant
contains one or more selected from a lubricant type component
having no polyoxyalkylene structure and a metal deactivation agent,
decomposition of the unsaturated fluorinated hydrocarbon
refrigerant caused by operation of the compressor and generation of
a polymerized paraffin originating from polymerization of a
polymerizable decomposed substance are prevented. Where, chemical
structure of the ether-based lubricant can be a polyether structure
which has not been denatured, and can also be a polyether structure
that a terminal structure of either one end or both ends thereof
has been denatured by an ether group, an ester group, etc.
[0009] In the above-described configuration, even if an unsaturated
fluorinated hydrocarbon refrigerant having a CH2=CH-- or CH2=CF--
group at an end of a molecule where thermal and chemical stability
is particularly low is used, generation of polymerized paraffin can
also be prevented effectively. Further, even if HFO1234yf and
HFO1234ze, which are typical refrigerants as unsaturated
fluorinated hydrocarbon refrigerant, are used in the
above-described configuration, generation of polymerized paraffin
can also be prevented effectively. An ester-based lubricant such as
polyol ester, an alcohol-based friction modifier such as an
aliphatic polyol having a carbon number in a range of 2 to 25, an
olefin-based friction modifier such as an olefin having a carbon
number in a range of 10 to 18, a polyolefin-based lubricant
comprising poly-.alpha.-olefin, alkyl aromatic lubricant such as
alkylbenzene and alkylnaphthalene, and a silicone-based lubricant
are preferred as a lubricant-type component having no
polyoxyalkylene structure. Benzotriazole is preferred as a metal
deactivating agent. When an acid capturing agent for capturing
hydrogen fluoride generated by decomposition of the unsaturated
fluorinated hydrocarbon refrigerant is used together in the
above-described configuration, the polymerized paraffin can be
prevented from generating further effectively. Epoxy-alkane having
a carbon number in a range of 8 to 25 is preferred as an acid
capturing agent.
[0010] The refrigeration circuit and the method for improving the
refrigeration circuit of the present invention can be applied to
any refrigeration circuit used in the area of home electronics,
residential air conditioning system, distribution system, etc., and
is suitable for a refrigeration circuit for an automotive air
conditioning system in particular. By applying the present
invention to a refrigeration circuit for an automotive air
conditioning system, it is possible to realize a refrigeration
circuit wherein the environmental load is reduced by using
unsaturated fluorinated hydrocarbon refrigerant such as HFO1234yf
and the comparable operational stability as before can be
achieved.
Effect According to the Invention
[0011] According to the present invention, in a refrigeration
circuit using a scroll compressor as a compressor, an unsaturated
fluorinated hydrocarbon refrigerant as refrigerant and an
ether-based lubricant having a polyoxyalkylene structure as
lubricant, by compensating for shortage in lubricating performance
of the ether-based lubricant by combined use of another lubricating
component having no polyoxyalkylene structure, exposure of active
metal surface accompanying a sliding movement of a compression
mechanism part is prevented, and therefore it is possible to
prevent the unsaturated fluorinated hydrocarbon refrigerant and the
polyoxyalkylene structure of the ether-based lubricant from
reacting through catalytic activity of the exposed active metal
surface under an atmosphere of high-temperature and high-pressure
refrigerant gas in the compression mechanism part. As a result, it
is possible to prevent the generation of polymerized paraffin which
becomes a cause of clogging in the refrigeration circuit and
degradation of refrigeration performance.
BRIEF EXPLANATION OF THE DRAWINGS
[0012] FIG. 1 is a schematic framework showing an example of a
basic equipment layout of a refrigeration cycle as an object of the
present invention.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0013] FIG. 1 shows a basic configuration of a refrigeration
circuit used in an air conditioning system for vehicles, etc. In
FIG. 1, refrigeration circuit 1 has compressor 2 for compressing
refrigerant, condenser 3 for condensing compressed refrigerant,
expansion valve 4 as a pressure reduction and expansion means for
reducing in pressure and expanding condensed refrigerant, and
evaporator 5 for evaporating pressure-reduced and expanded
refrigerant, where the refrigerant is circulated in refrigeration
circuit 1 as changing its state.
[0014] The scroll compressor used in the present invention is not
particularly limited. As a configuration material for the
compressor, not only an Fe-based material but also a light
metal-based material such as aluminum, magnesium or an alloy
thereof can be used. In a scroll on a movable side in a compression
mechanism part, the light metal-based material such as aluminum,
magnesium or an alloy thereof, which has a lighter specific gravity
than the Fe-based material, is used in many cases in order to
reduce an inertial force. Though these Fe-based material and light
metal-based material have high reactivity in a state of pure metal
material, their surfaces are generally covered with an oxidized
coating layer, and further, by performing surface treatment for the
purpose of improvement of lubricity and protection, their surfaces
are in a state where activity of the metal material is suppressed.
However, if lubricating performance of refrigeration machine oil is
not quite enough, the active metal surface will be exposed because
the oxidized coating layer is lost due to friction, etc. caused by
a rotational movement of a rotational scroll. When the active metal
surface is exposed, the active metal surface exhibits extremely
high catalytic activity because of the high reactivity of the metal
material thereof. Thus, when an ether-based lubricant and an
unsaturated fluorinated hydrocarbon refrigerant come into contact
with the active metal surface under an atmosphere of
high-temperature high-pressure refrigerant, the unsaturated
fluorinated hydrocarbon refrigerant reacts with a polyoxyalkylene
structure of the ether-based lubricant by the catalytic activity of
the active metal surface. By this reaction, decomposition of the
unsaturated fluorinated hydrocarbon refrigerant and generation of a
polymerizable olefin as a decomposed substance occur, and further,
this polymerizable olefin polymerizes to form a polymerized
paraffin by the catalytic activity of the active metal surface
under the atmosphere of high-temperature and high-pressure
refrigerant gas. However, according to the present invention,
because the ether-based lubricant contains a lubricant type
component having no polyoxyalkylene structure and the lubricant
type component does not react with the unsaturated fluorinated
hydrocarbon refrigerant even under the atmosphere of
high-temperature and high-pressure refrigerant gas, the exhibition
of the active metal surface is prevented by compensating for a
shortage of lubricating performance of the ether-based lubricant,
and thereby preventing decomposition of the unsaturated fluorinated
hydrocarbon refrigerant, generation of the polymerizable olefin as
the decomposed substance, and generation of the polymerized
paraffin originating from polymerization of the polymerizable
olefin.
[0015] As the unsaturated fluorinated hydrocarbon refrigerant used
in the present invention, for example, a hydrofluoropropene such as
1,2,3,3-tetrafluoro-1-propene (HFC-1234ye);
1,3,3,3-tetrafluoro-1-propene (HFC-1234ze);
2,3,3,3-tetrafluoro-1-propene (HFC-1234yf);
1,1,2,3-tetrafluoro-1-propene (HFC-1234yc);
1,1,3,3-tetrafluoro-1-propene (HFC-1234zc);
2,3,3-trifluoro-1-propene (HFC-1243yf); 3,3,3-trifluoro-1-propene
(HFC-1243zf); 1,1,2-trifluoro-1-propene (HFC-1243yc);
1,1,3-trifluoro-1-propene (HFC-1243ye); 1,3,3-trifluoro-1-propene
(HFC-1243ze); and 3,3,3,-trifluoropropene (HFC-1243zf): a
hydrofluorobutene such as 2,3,3,4,4,4-hexafluoro-1-butene
(CF.sub.3CF.sub.2CF.dbd.CH.sub.2);
3,3,3-trifluoro-2-(trifluoromethyl)-1-propene
(CH.sub.2.dbd.C(CF.sub.3).sub.2); 1,1,1,3,4-pentafluoro-2-butene
(CF.sub.3CH.dbd.CFCH.sub.2F); 3,3,4,4,4-pentafluoro-1-butene
(CF.sub.3CF.sub.2CH.dbd.CH.sub.2); 2,3,3,4,4-pentafluoro-1-butene
(CH.sub.2.dbd.CFCF.sub.2CHF.sub.2); 3,3,4,4-tetrafluoro-1-butene
(CH.sub.2.dbd.CHCF.sub.2CHF.sub.2);
3,3-difluoro-2-(difluoromethyl)-1-propene
(CH.sub.2.dbd.C(CHF.sub.2).sub.2);
3,3,4,4,4-pentafluoro-2-(trifluoromethyl)-1-butene
(CH.sub.2.dbd.C(CF.sub.3)CF.sub.2CF.sub.3);
3,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene
((CF.sub.3).sub.2CFCH.dbd.CH.sub.2);
2,4,4,4-tetrafluoro-3-(trifluoromethyl)-1-butene
(CH.sub.2.dbd.CFCH(CF.sub.3).sub.2); and
4,4,4-trifluoro-3-(trifluoromethyl)-1-butene
(CH.sub.2.dbd.C(CF.sub.3)CH.sub.2CF.sub.3): a hydrofluoropentene
such as 3,3,4,4,5,5,5-heptafluoro-1-pentene
(CF.sub.3CF.sub.2CF.sub.2CH.dbd.CH.sub.2);
2,3,3,4,4,5,5-heptafluoro-1-pentene
(CH.sub.2.dbd.CFCF.sub.2CF.sub.2CHF.sub.2);
3,3,4,5,5,5-hexafluoro-1-pentene
(CH.sub.2.dbd.CHCF.sub.2CHFCF.sub.3); and
4,5,5,5-tetrafluoro-4-(trifluoromethyl)-1-pentene
(CH.sub.2.dbd.CHCH.sub.2CF(CF.sub.3).sub.2): and a
hydrofluorohexene such as 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene
(CF.sub.3CF.sub.2CF.sub.2CF.sub.2CH.dbd.CH.sub.2); and
4,4,5,5,6,6,6-heptafluoro-1-hexene
(CH.sub.2.dbd.CHCH.sub.2CF.sub.2CF.sub.2CF.sub.3) can be
exemplified. In particular, among unsaturated fluorinated
hydrocarbon refrigerants, one which has a group of CH2=CH-- or
CH2=CF-- at an end of the molecule is more significant in a degree
to generate a polymerized paraffin by reacting with an ether-based
lubricant having a polyoxyalkylene structure in a scroll compressor
than that which does not have such a group at an end of the
molecule. Therefore, in a refrigeration circuit using an
unsaturated fluorinated hydrocarbon refrigerant having such a
group, applying the present invention is particularly
effective.
[0016] The above-described compounds are used as a single one or a
mixture of two or more. In addition, the above-described compounds
can also be used in combination with a saturated halogenated
hydrocarbon refrigerant or hydrocarbon-based refrigerant. As the
typical saturated halogenated hydrocarbon refrigerant and
hydrocarbon-based refrigerant, for example,
1,1,1,2-tetrafluoroethane (R134a), 1,1,2-difluoroethane (R152a),
difluoromethane (R32), pentafluoroethane (R125),
1,1,1-trifluoroethane (R143a), 1,1,1,2,3,3,3-heptafluoropropane
(R227ea), 1,1,1,2,3,4,4,5,5,5-decafluoropentane (R43-10mee),
1,1,1,3,3-pentafluorobutane (R365mfc),
2,2-dichloro-1,1,1-trifluoroethane (R123),
1,1,1,3,3-pentafluoropropane (R245fa),
1,2-dichloro-1,1,2,2-tetrafluoroethane (R114),
1,1,1,3,3,3-hexafluoropropane (R236fa) and dichlorodifluoromethane
(R12) can be exemplified. As a typical hydrocarbon refrigerant, for
example, propane, propylene, cyclopropane, n-butane, isobutane,
n-pentane, 2-methylbutane (isopentane), cyclobutane, cyclopentane,
2,2-dimethylpropane, 2,2-dimethylbutane, 2,3-dimethylbutane,
2,3-dimethylpentane, 2-methylhexane, 3-methylhexane,
2-methylpentane, 3-ethylpentane, 3-methylpentane, cyclohexane,
n-heptane, methylcyclopentane, and n-hexane can be exemplified.
[0017] As the lubricant type component having no polyoxyalkylene
structure used as a polymerized paraffin inhibitor in the present
invention, for example, an alcohol-based friction modifier; an
olefin-based friction modifier; an ester-based lubricant such as a
diester, a polyol ester, etc.; an alkyl aromatic lubricant such as
alkylbenzene and alkylnaphthalene, etc.; and a silicone-based
lubricant can be exemplified, and particularly, the alcohol-based
friction modifier, the olefin-based friction modifier and the
ester-based lubricant are preferred due to their significant effect
on preventing a polymerized paraffin. The ester-based lubricant is
preferred in particular.
[0018] As the alcohol-based friction modifier used as a polymerized
paraffin inhibitor in the present invention, for example, a higher
alcohol having a carbon number in a range of 6 to 20 such as an
octyl alcohol, a decyl alcohol, myristyl alcohol, lauryl alcohol,
lauryl alcohol, myristyl alcohol, a dodecyl alcohol, cetyl alcohol,
palmityl alcohol, oleyl alcohol, stearyl alcohol, linoleyl alcohol,
etc.; a dihydric alcohol having a carbon number in a range of 2 to
25 such as ethylene glycol, diethylene glycol, propylene glycol,
dipropylene glycol, neopentyl glycol, 1,3-propanediol,
1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol,
1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol,
2-methyl-2,4-pentanediol, 1,7-heptanediol,
2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol,
1,8-octanediol, 1,9-nonanediol, 2-butyl-2-ethyl-1,3-propanediol,
1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol,
1,13-tridecanediol, 1,14-tetradecanediol, 1,15-heptadecanediol,
1,16-hexadecanediol, 1,17-heptadecanediol, 1,18-octadecanediol,
1,19-nonadecanediol, 1,20-icosanediol, etc.; a trihydric alcohol
such as glycerin, trimethylolethane, trimethylolpropane,
trimethylolbutane, 1,2,4-butanetriol, 1,3,5-pentanetriol,
1,2,6-hexanetriol, etc.; and a polyol having a carbon number in a
range of 3 to 20 such as a dimer and a trimer thereof. Among
above-described compounds, the aliphatic polyol having a carbon
number in a range of 2 to 25 is preferred. An amount of addition of
the alcohol-based friction modifier to the ether-based lubricant is
preferably in a range of 0.1 to 10 wt. %, and the amount of
addition thereof to an amount of refrigerant enclosed is preferably
in a range of 0.02 to 2 wt. %.
[0019] As the olefin-based friction modifier used as a polymerized
paraffin inhibitor in the present invention, for example, 1-hexene,
1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene,
1-tridecene, 1-tridecene, 1-tetradecene, 1-pentadecene,
1-hexadecene, 1-heptadecene, 1-octadecene, a linear .alpha.-olefin;
a branched .alpha.-olefin such as 4-methyl-1-pentene,
8-methyl-1-nonene, 7-methyl-1-decene, 6-methyl-1-undecene,
6,8-dimethyl-1-decene, etc. can be exemplified, and among these
compounds, a linear .alpha.-olefin having a carbon number in a
range of 10 to 16 is preferred. An amount of addition of the
olefin-based friction modifier to an ether-based lubricant is
preferably in a range of 0.5 to 10 wt. %, and the amount of
addition thereof to an amount of refrigerant enclosed is preferably
in a range of 0.1 to 2 wt. %.
[0020] As the ester-based lubricant used as a polymerized paraffin
inhibitor in the present invention, for example, a diester derived
from an aliphatic diacid and monohydric alcohols, and a polyol
ester derived from a polyol having a valence number of three or
more and monovalent aliphatic acids can be exemplified. As the
aliphatic diacid which can be a raw material of the diester, for
example, an aliphatic diacid having a carbon number in a range of 5
to 10 such as glutaric acid, pimelic acid, suberic acid, azelaic
acid, sebacic acid, 1,2-cyclohexane dicarboxylic acid,
4-cyclohexene-1,2-dicarboxylic acid, etc. can be exemplified, and
as the monohydric alcohol, for example, a monohydric alcohol having
a carbon number in a range of 4 to 18 such as butanol, pentanol,
hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol,
tridecanol, tetradecanol, pentadecanol, etc. can be exemplified. As
the polyol which can be a raw material of the polyol ester, for
example, a dihydric alcohol having a carbon number in a range of 2
to 15 such as ethylene glycol, 1,3-propanediol, propylene glycol,
1,4-butanediol, 1,2-butanediol, 1,2-butanediol,
2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol,
1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 1,7-heptanediol,
2-methyl-2-propyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol,
1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol,
1,12-dodecanediol, etc.; a trihydric alcohol having a carbon number
in a range of 3 to 8 such as trimethylol ethane, trimethylol
propane, trimethylol butane, glycerin, etc.; a polyol having a
valence number of 3 or more such as pentaerythritol,
dipentaerythritol, diglycerin, sorbitol, xylitol, etc. can be
exemplified, and, in particular, a hindered alcohol such as
neopentyl glycol, trimethylol ethane, trimethylol propane,
trimethylol propane, trimethylol butane, pentaerythritol is
preferred. As the aliphatic acid which can be a raw material of a
polyol ester, for example, an aliphatic acid having a carbon number
in a range of 5 to 20 such as pentanoic acid, hexanoic acid,
heptanoic acid, octanoic acid, nonanoic acid, decanoic acid,
undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic
acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid,
octadecanoic acid, nonadecanoic acid, icosanoic acid, oleic acid,
etc. can be exemplified. The polyol ester may have two or more
ester groups, may be a partial ester in which some of the hydroxyl
groups of a polyol remain unesterified, or may be a total ester in
which all the hydroxyl groups are esterified. An amount of content
of the ester-based lubricant to the ether-based lubricant is
preferably in a range of 1 to 99 wt. %. An amount of addition of
the ester-based lubricant to an amount of refrigerant enclosed is
preferably in a range of 0.2 to 20 wt. %.
[0021] As the polyolefin-based lubricant used as a polymerized
paraffin inhibitor in the present invention, for example, an
oligomer or co-oligomer of .alpha.-olefin having a carbon number in
a range of 2 to 16 such as an octene oligomer, a decene oligomer,
an ethylene-propylene co-oligomer, etc. can be exemplified. An
amount of addition of the olefin-based lubricant to the ether-based
lubricant is preferably in a range of 0.1 to 3 wt. %, and the
amount of addition thereof to an amount of refrigerant enclosed is
preferably in a range of 0.02 to 0.6 wt. %.
[0022] As the alkyl aromatic lubricant used as a polymerized
paraffin inhibitor in the present invention, for example, an
alkylbenzene, which has 1 to 4 alkyl groups having a carbon number
in a range of 1 to 15 and in which the total carbon number of these
alkyl groups is in a range of 9 to 15, can be exemplified. As the
alkyl group, for example, methyl group, ethyl group, propyl group,
butyl group, pentyl group, hexyl group, heptyl group, octyl group,
nonyl group, decyl group, undecyl group, dodecyl group, tridecyl
group, tetradecyl group, pentadecyl group, hexadecyl group,
heptadecyl group, octadecyl group, nonadecyl group, etc. can be
exemplified. Further, as the alkyl aromatic lubricant, an
alkylnaphthalene such as a n-propyl naphthalene, an isopropyl
naphthalene, a butyl naphthalene, a pentyl naphthalene, an
ethyl-propyl naphthalene, a methyl-pentyl naphthalene, an
ethyl-butyl naphthalene, a dimethyl-butyl naphthalene, a
methyl-hexyl naphthalene, an ethyl-pentyl naphthalene, a
propyl-butyl naphthalene, a dimethyl-pentyl naphthalene, a
methyl-heptyl naphthalene, an ethyl-hexyl naphthalene, a
propyl-pentyl naphthalene, a dimethyl-hexyl naphthalene, an
ethyl-methyl naphthalene, a diethyl naphthalene, a methyl-propyl
naphthalene, a methyl-isopropyl naphthalene, a dipropyl
naphthalene, a butyl-methyl naphthalene, a dibutyl naphthalene, a
trimethyl naphthalene, a triethyl naphthalene, an ethyl-dimethyl
naphthalene, a diethyl-methyl naphthalene, a dimethyl-propyl
naphthalene, a methyl-dipropyl naphthalene, a butyl-dimethyl
naphthalene, etc. can be exemplified. It is preferred that an
amount of addition of the alkyl aromatic lubricant to the
ether-based lubricant is in a range of 0.5 to 10 wt. %, and it is
preferred that the amount of addition thereof to the refrigerant
enclosed is in a range of 0.1 to 2 wt. %.
[0023] As the metal deactivation agent which is used as the
polymerized paraffin inhibitor in the present invention, for
example, a triazole derivative such as triazole and
N,N-dialkyl-triazole-alkylamine, a benzotriazole derivative such as
benzotriazole and N,N-dialkyl-benzotriazole-methylamine; a
thiadiazole derivative such as thiadiazole, benzotriazole
thiadiazole and 2,5-dialkylmercapto-1,3,4-thiadiazole; a
benzimidazole derivative such as benzimidazole and
2-alkyldithio-benzimidazole can be exemplified. Among these
compounds, benzotriazole and its derivatives are preferred. An
amount of addition of the metal deactivation agent to the
ether-based lubricant is preferably in a range of 0.5 to 10 wt. %,
and the amount of addition thereof to an amount of refrigerant
enclosed is preferably in a range of 0.1 to 2 wt. %.
[0024] Even when generation of the polymerized paraffin in a
refrigeration circuit is prevented by a condition where the
ether-based lubricant contains a lubricant type component having no
polyoxyalkylene structure, there is a fear that hydrogen fluoride
originating from decomposition of the unsaturated fluorinated
hydrocarbon refrigerant may be generated in the refrigeration
circuit. If hydrogen fluoride is generated, there is a fear that it
may promote further decomposition of the unsaturated fluorinated
hydrocarbon refrigerant. Therefore, in addition to a lubricant type
component as a polymerized paraffin inhibitor, it is preferred that
an appropriate amount of an acid capturing agent is added to the
refrigeration circuit. This acid capturing agent may be added
individually to the refrigeration circuit apart from refrigerant
and refrigeration machine oil, or may be added at an appropriate
amount as a preparative mixture with refrigerant or in combination
with various additive agents, which are typically contained in
refrigeration machine oil, such as an antioxidant and an extreme
pressure agent. The acid capturing agent can also contribute to
prevention of corrosion and deterioration of a compressor and pipe
of the refrigeration circuit. As the acid capturing agent, for
example, an epoxy compound such as an epoxide alkane, an aliphatic
acid glycidyl ester, an aromatic carboxylic acid glycidyl ester; an
orthoester; an oxirane compound; acetals; a carbodiimide can be
exemplified. Among these compounds, for example, a glycidyl ester
of an aliphatic monocarboxylic acid having a carbon number in a
range of 6 to 16 such as 2-ethylhexanoic acid glycidyl ester,
3,5,5-trimethylhexanoic acid glycidyl acid, capric acid glycidyl
ester, lauric acid glycidyl ester, versatic acid glycidyl ester,
myristic acid glycidyl ester, etc. is preferred; and the epoxy
alkane having a carbon number in a range of 8 to 25 such as
1,2-epoxynonane, 1,2-epoxydecane, 1,2-epoxyundecane,
1,2-epoxydodecane, 1,2-epoxytetradecane, 1,2-epoxypentadecane,
1,2-epoxyhexadecane, 1,2-epoxyheptadecane, 1,2-epoxyoctadecane,
1,2-epoxynonadecane, etc. is preferred in particular. An amount of
addition of the acid capturing agent to the ether-based lubricant
is preferably in a range of 0.5 to 15 wt. %, and the amount of
addition thereof to an amount of refrigerant enclosed is preferably
in a range of 0.1 to 3 wt. %.
Practical Examples
[0025] The effect of prevention of generation of polymerized
paraffin by the present invention can be confirmed by the following
practical examples and comparative examples. In the practical
examples and comparative examples, the refrigeration circuit shown
in FIG. 1 is used. A scroll compressor in the refrigeration circuit
has a movable scroll made of an aluminum alloy and a fixed scroll
anodized with an aluminum alloy. The refrigeration circuit is
filled with a specific amount of HFO1234yf refrigerant, and the
scroll compressor is filled with a specific amount of a mixture
whose prescription is described in Table 1. In the practical
examples and comparative examples, tricresyl phosphate as the
extreme pressure agent is added to the ether-based lubricant at
1.0% thereto. The rotational speed of the scroll compressor is set
at 6,000 rpm, and the refrigeration circuit is operated
continuously for 400 hours at this rotational speed. After the
operation is finished, the inside of the compressor and the inside
of the pipe of the refrigeration circuit are inspected in order to
confirm the presence or absence of generation of a wax-like solid
(a polymerized paraffin). By this confirmation examination, the
result described in Table 1 is obtained. The criteria in the column
of effect in Table 1 are as follows.
[0026] .smallcircle.: There is no solid which can be confirmed
visually.
[0027] x: There is a solid which can be confirmed visually.
TABLE-US-00001 TABLE 1 Lubricant Type Component Effectiveness
Having No Polyoxyalkylene of Inhibiting Ether-based Structure
(Polymerized Acid Capturing Polymerized Lubricant Paraffin
Inhibitor) Agent Paraffin Practical PPG Trimethylolpropane- --
.smallcircle. Example 1 trilaurate 1% Practical PPG the same as
above 1,2-Epoxy- .smallcircle. Example 2 dodecane 1% Practical PPG
Ethyleneglycol 1% -- .smallcircle. Example 3 Practical PPG the same
as above 1,2-Epoxy- .smallcircle. Example 4 tetradecane 1%
Practical PPG 1-Hexadecene 1% -- .smallcircle. Example 5 Practical
PPG Decene olygomer 1% -- .smallcircle. Example 6 Practical PPG
Dibuthyl Naphthalene 1% -- .smallcircle. Example 7 Practical PPG
Silicone Oil 1% -- .smallcircle. Example 8 Practical PPG
Benzotriazole 1% -- .smallcircle. Example 9 Comparative PPG -- -- x
Example
[0028] In the above-described table, PPG means a polyalkylene
glycol that a polypropylene glycol as a main structure is denatured
with an ether at an end of the molecule, and % means wt. % to an
amount of refrigerant enclosed.
[0029] As shown in Table 1, in case such as practical examples 1 to
8 where any of various lubricant type components having no
polyoxyalkylene structure is added as the polymerized paraffin
inhibitor to an ether-based lubricant (PAG), a polymerized paraffin
is not generated even under a high-speed and high-load condition at
a rotational speed of 6,000 rpm and a continuous operating time of
400 hours, whereas in case such as comparative example where a
lubricant type component having no polyoxyalkylene structure is not
added, a polymerized paraffin is generated under the same
condition.
INDUSTRIAL APPLICATIONS OF THE INVENTION
[0030] The present invention can be applied to any refrigeration
circuit used in the area of home electronics, air conditioning
systems for housing, logistics, etc., and specifically, in a
refrigeration circuit for an air conditioning system for vehicles,
it is possible to realize a refrigeration circuit which reduces the
environmental load by using an unsaturated fluorinated hydrocarbon
refrigerant such as HFO1234yf and which achieves a conventional
operation stability.
EXPLANATION OF SYMBOLS
[0031] 1: refrigeration circuit [0032] 2: compressor [0033] 3:
condenser [0034] 4: expansion valve as pressure reduction and
expansion means [0035] 5: evaporator
* * * * *