FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
REFRIGERATION CYCLE DEVICE;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

- 2 -
DESCRIPTION
TITLE OF INVENTION:
Refrigeration Cycle Device
5 TECHNICAL FIELD
[0001] The present disclosure relates to a refrigeration cycle device.
BACKGROUND ART
[0002] The refrigerant used for a refrigeration cycle device is currently restricted by,
for example, the Fluorocarbon Emissions Control Act (enacted on April 2015).
10 Specifically, the upper limit is set on the Global Warming Potential (GWP) value of the
refrigerant to be used. Thus, use of a refrigerant having a further low GWP is needed.
[0003] In recent years, for example, hydrocarbons having 1 to 4 carbon atoms such as
R-290 (propane), R-1270 (propylene), R-600 (butane), and R-600a (isobutane) are
examined as the refrigerant having a low GWP value. The hydrocarbons having 1 to
15 4 carbon atoms have a further lower GWP value than saturated fluorinated hydrocarbon
compounds (hydrofluorocarbons), which are refrigerants having a relatively low GWP
value.
[0004] However, the hydrocarbons having 1 to 4 carbon atoms have higher
flammability than hydrofluorocarbons. For example, in the international standard
20 ISO-817, which defines safety classification for refrigerants, R-32 (difluoromethane),
one of the hydrofluorocarbons, is registered as lower flammability (Class 2L), and on
the other hand, R-290, R-1270, R-600, and R-600a are registered as higher
flammability (Class 3).
[0005] For example, when a refrigerant having high flammability, such as a
25 hydrocarbon having 1 to 4 carbon atoms, is used as the refrigerant for a refrigeration
cycle device, it is preferable to take a measure of making the refrigerant recognizable
by the sense of smell or the sense of vision.
[0006] As the measure of making the refrigerant recognizable by the sense of smell, for
example, Patent Literature 1 (WO 2021/166028) discloses a method including mixing a
- 3 -
sulfur-based odorant with the refrigerant and detecting the leakage of the refrigerant by
an unpleasant odor.
[0007] Patent Literature 2 (Japanese Patent Laying-Open No. 2002-38135) discloses
that tetrahydrothiophene (THT) is preferable as an odorant since it does not react with
5 the material for the refrigerating circuit, has compatibility with the refrigerant, and has
compatibility with refrigeration oil.
CITATION LIST
PATENT LITERATURE
[0008] PTL 1: WO 2021/166028
10 PTL 2: Japanese Patent Laying-Open No. 2002-38135
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0009] However, the inventors have found the following: sulfur-based odorants such as
THT have polarity due to the bias of charge in the molecule; thus, when a refrigeration
15 oil having high polarity is used, the sulfur-based odorant is dissolved in the
refrigeration oil in a compressor so that the amount of the sulfur-based odorant that
circulates in the refrigerant circuit with the refrigerant is reduced; and when the
refrigerant is released from the refrigeration cycle device, the refrigerant is hardly
detectable by the sense of smell. In particular, since polyalkylene glycol, polyol ester,
20 polyvinyl ether, and the like used as the base oil for the refrigeration oil contain a large
amount of oxygen (O), which is an element having a large electronegativity in the
molecular structure, they are refrigeration oils having high polarity and dissolve a large
amount of sulfur-based odorants depending on the composition.
[0010] The present disclosure has been made in view of the above problems, and an
25 object of the present disclosure is to provide a refrigeration cycle device that suppresses
the dissolution of a sulfur-based odorant in a refrigeration oil and makes the leakage of
a refrigerant recognizable by the sense of smell.
SOLUTION TO PROBLEM
[0011] A refrigeration cycle device according to one aspect of the present disclosure
- 4 -
includes a refrigerant circuit including a compressor, wherein
a refrigerant is enclosed in the refrigerant circuit,
the refrigerant contains a hydrocarbon having 1 to 4 carbon atoms and a sulfurbased odorant,
5 the compressor is filled with a refrigeration oil,
the refrigeration oil contains a base oil, and
the ratio of the number of oxygen atoms to the number of carbon atoms in the
molecular structure of the base oil is less than 0.50.
[0012] A refrigeration cycle device according to another aspect of the present
10 disclosure includes a refrigerant circuit including a compressor, wherein
a refrigerant is enclosed in the refrigerant circuit,
the refrigerant contains a hydrocarbon having 1 to 4 carbon atoms and a sulfurbased odorant,
the compressor is filled with a refrigeration oil,
15 the refrigeration oil contains a base oil, and
the difference between the HSP distance between the base oil and the sulfurbased odorant and the HSP distance between the base oil and the hydrocarbon having 1
to 4 carbon atoms is -2.0 or more.
ADVANTAGEOUS EFFECT OF INVENTION
20 [0013] According to the present disclosure, a refrigeration cycle device that suppresses
the dissolution of the sulfur-based odorant in the refrigeration oil and makes the
leakage of the refrigerant recognizable by the sense of smell can be provided.
BRIEF DESCRIPTION OF DRAWINGS
[0014] Fig. 1 is a schematic configuration diagram showing one example of a
25 refrigeration cycle device according to an embodiment 1.
Fig. 2 is a schematic cross-sectional view showing one example of a compressor
of the refrigeration cycle device according to embodiment 1.
Fig. 3 is a graph showing a relationship between the concentration of
tetrahydrothiophene in an enclosed refrigerant and the concentration of
- 5 -
tetrahydrothiophene in collected refrigerant gas.
Fig. 4 is a graph showing a relationship between the concentration of
tetrahydrothiophene in a sample gas and the odor index (equivalent value).
DESCRIPTION OF EMBODIMENTS
5 [0015] Hereinafter, the embodiments of the present disclosure will be described with
reference to the drawings. In the drawings, the dimensional relationship of the length,
width, thickness, depth, and the like is appropriately changed for the purpose of clarity
and simplification of the drawing, and does not indicate the actual dimensional
relationship.
10 [0016] Embodiment 1.
First, the outline of the refrigeration cycle device of the present embodiment is
briefly described. Fig. 1 is a schematic configuration diagram showing one example
of the refrigeration cycle device according to embodiment 1. An outdoor unit 1
includes a compressor 3, a condenser 4, an outdoor blower 5, and the others, and
15 compressor 3 and condenser 4 are connected via piping. An indoor unit 2 includes an
expansion valve 6, an evaporator 7, an indoor blower 8, and the others, and expansion
valve 6 and evaporator 7 are connected via piping.
[0017] Compressor 3 of outdoor unit 1 and evaporator 7 of indoor unit 2 are connected
via a gas pipe 10. Condenser 4 of outdoor unit 1 and expansion valve 6 of indoor unit
20 2 are connected via a liquid pipe 9.
[0018] A refrigerant circuit 100 is formed by such a refrigeration cycle device
configuration, and a refrigerant is circulated in refrigerant circuit 100 via liquid pipe 9
and gas pipe 10.
[0019] Compressor 3 compresses the refrigerant that has turned into a gaseous state in
25 gas pipe 10. Condenser 4 cools the gaseous refrigerant that has been compressed by
compressor 3 to form a high-pressure liquid refrigerant or a gas-liquid two-phase
refrigerant. Expansion valve 6 reduces the pressure of the high-pressure liquid
refrigerant or the gas-liquid two-phase refrigerant. Evaporator 7 heats the refrigerant
reduced in pressure to form a low-pressure gaseous refrigerant. Compressor 3 sucks
- 6 -
and recompresses the refrigerant that has turned into a low-pressure gaseous state by
evaporator 7.
[0020] Outdoor blower 5 is a constituent that sends air to condenser 4, and is provided
to promote the absorption and release of heat by the heat exchange of the refrigerant
5 flowing in condenser 4 with air. Indoor blower 8 is a constituent that sends air to
evaporator 7, and is provided to promote the absorption and release of heat by the heat
exchange of the refrigerant flowing in evaporator 7 with air.
[0021] In the present embodiment, the configuration for carrying out the heat exchange
of condenser 4 and evaporator 7 with air is described, but the configuration is not
10 limited to this configuration. For example, condenser 4 and evaporator 7 may be
configured so as to exchange heat with not air but a liquid such as water.
[0022] In the present embodiment, the configuration in which evaporator 7 is provided
in indoor unit 2 is described, but the configuration is not limited to this configuration.
For example, condenser 4 may be arranged on the inside, and evaporator 7 may be
15 arranged on the outside.
[0023] With respect to outdoor unit 1 as described above, for example, a four-way
valve or a combination of a plurality of valves may be arranged, or a switching
mechanism that switches an inlet pipe and a discharge pipe of compressor 3 may be
provided. By providing a switching mechanism, the heat exchanger in outdoor unit 1
20 functions as evaporator 7 and the heat exchanger in indoor unit 2 functions as
condenser 4, whereby heating of the indoor using the outdoor heat is enabled.
[0024] The refrigeration cycle device may be, for example, any of a device capable of
carrying out both cooling and heating, a device capable of carrying out only cooling, or
a device capable of carrying out only heating. The application of the refrigeration
25 cycle device according to the present embodiment is not limited to air conditioning, and
may be freezing, refrigerating, and hot water supply, for example.
[0025] In the present embodiment, the configuration in which expansion valve 6 is
provided in indoor unit 2 is described, but the configuration is not limited to this
configuration. For example, expansion valve 6 may be arranged in outdoor unit 1.
- 7 -
For example, expansion valve 6 may be provided on both outdoor unit 1 and indoor
unit 2. Further, for example, a plurality of indoor units 2 or a plurality of outdoor
units 1 may be provided in refrigerant circuit 100.
[0026]
5 Next, the refrigerant enclosed in the refrigerant circuit in the present
embodiment will be described. The refrigerant contains a main component that
functions as the refrigerant, and further contains a sulfur-based odorant for detecting
the leakage of the refrigerant.
[0027] Herein, the aforementioned "main component" is the component excluding the
10 sulfur-based odorant and impurities (such as air, moisture, and by-products that may be
mixed during the synthesis or purification of a refrigerant compound) from the
refrigerant. The main component of the refrigerant may be a single refrigerant or a
mixture of a plurality of refrigerants. The content of the main component in the
refrigerant is more than 50% by mass, preferably 90% by mass or more, and more
15 preferably 95% by mass or more.
[0028] The main component functions as the refrigerant is a hydrocarbon having 1 to 4
carbon atoms. Examples of the hydrocarbon having 1 to 4 carbon atoms include R290 (propane), R-1270 (propylene), R-600 (butane), and R-600a (isobutane). The
hydrocarbon having 1 to 4 carbon atoms is preferably propane, propylene, or a mixture
20 thereof. This is because they have an operating pressure suitable for use for the
refrigeration cycle device. In view of oxidation stability, propane is more preferable.
According to the Sixth Assessment Report of the IPCC, propane has a GWP value
significantly as low as 0.02 and high cooling performance, and may thus contribute to
the reduction in environmental load during the production and operation of the
25 refrigeration cycle device.
[0029] The refrigerant may further contain a halogenated hydrocarbon. Examples of
the halogenated hydrocarbon include chlorofluorocarbon, hydrochlorofluorocarbon,
hydrofluorocarbon, hydrofluoroolefin, hydrochlorofluoroolefin, and fluoroiodocarbon.
The halogenated hydrocarbon, in which a hydrogen atom of a hydrocarbon is replaced
- 8 -
with a halogen atom, has a lower flammability than the hydrocarbon, and can reduce
the flammability of the refrigerant by being mixed. The refrigerant circuit may be
filled with the halogenated hydrocarbon in a state of being mixed with the hydrocarbon
having 1 to 4 carbon atoms, or the refrigerant circuit filled with the halogenated
5 hydrocarbon or the refrigerant circuit in which the halogenated hydrocarbon slightly
remains may be additionally filled with the hydrocarbon having 1 to 4 carbon atoms.
[0030] The halogenated hydrocarbon preferably has an operating pressure similar to
that of the hydrocarbon having 1 to 4 carbon atoms. Consequently, azeotropy with the
hydrocarbon having 1 to 4 carbon atoms, which is the main component of the
10 refrigerant, increases, and high cooling performance can be obtained. Such a
halogenated hydrocarbon is a halogenated hydrocarbon having 1 to 4 carbon atoms, and
more preferably a halogenated hydrocarbon having 1 to 3 carbon atoms. This is
because the halogenated hydrocarbon has a large molecule by halogenation of a
hydrocarbon as compared with the hydrocarbon, and has a reduced operating pressure
15 as compared with a hydrocarbon having the same number of carbon atoms. Examples
of the halogenated hydrocarbon having 1 to 3 carbon atoms include HFC-23, HFC-32,
HFC-41, HFC-125, HFC-134, HFC-134a, HFC-143, HFC-143a, HFC-152, HFC-152a,
HFC-161, HFO-1141, HFO-1132a, HFO-1132 (E), HFO-1132 (Z), HFO-1123, HFO1225ye (Z), HFO-1225ye (E), HFO-1225zc, HFO-1234yf, HFO-1234ze (E), HFO20 1234ze (Z), HFO-1234ye (Z), HFO-1234ye (E), HFO-1243zf, HFO-1252zf, HFO1261yf, FIC-13I1 (CF3I), HCFC-22, and CFC-12.
[0031] The refrigerant may contain carbon dioxide (R-744). Carbon dioxide has a
GWP as low as 1 and may thus contribute to the reduction in environmental load during
the production of the refrigeration cycle device. In addition, carbon dioxide is non25 flammable and can thus reduce the flammability of the refrigerant by being mixed.
[0032] When air is contained in the refrigerant, the deterioration of the refrigerant, the
sulfur-based odorant, the refrigeration oil mentioned later, materials in the compressor,
and the others may be promoted, and thus, the air in the refrigerant circuit is preferably
removed before the refrigerant circuit is filled with the refrigerant.
- 9 -
[0033] (Sulfur-based odorant)
The sulfur-based odorant blended in the refrigerant is an odorant containing a
sulfur element. Examples of the sulfur-based odorant include mercaptans, sulfides,
and thiophenes. Examples of mercaptans include methyl mercaptan (MM), ethyl
5 mercaptan (EM), normal propyl mercaptan (NPM), isopropyl mercaptan (IPM), and
tert-butyl mercaptan (TBM); examples of sulfides include dimethyl sulfide (DMS),
diethyl sulfide (DES), and methyl ethyl sulfide (MES); and examples of thiophenes
include tetrahydrothiophene (THT). These sulfur-based odorants are compounds that
have been used in fuel gas and have an unpleasant odor. One of these sulfur-based
10 odorants may be used singly, or two or more thereof may be used in combination.
[0034] The sulfur-based odorant is preferably EM, NPM, IPM, TBM, DMS, MES,
THT, which are also used in fuel gas for households, or a mixture thereof. Mixing a
sulfur-based odorant used in fuel gas for households in the refrigerant enables the
leakage of the refrigerant to be easily detected by an unpleasant odor inherent in the
15 sulfur-based odorant.
[0035] The sulfur-based odorant is more preferably THT. THT is chemically stable
as compared with mercaptans and sulfides, so that it hardly causes a decomposition
reaction or a corrosion reaction in the refrigerant circuit, and THT also hardly causes
solidification in the refrigerant circuit because of its melting point as low as -96C.
20 [0036] The content of the sulfur-based odorant is preferably 50 ppm by mass or more
and less than 1,100 ppm by mass. The reason for this is as follows: when the content
of the sulfur-based odorant is within the above range, the leakage of the refrigerant
from the refrigerant circuit can be easily detected and a not excessively unpleasant odor
is obtained. The content of the sulfur-based odorant is more preferably 90 ppm by
25 mass or more and less than 1,026 ppm by mass, and further preferably 176 ppm by
mass or more and less than 987 ppm by mass.
[0037] However, the sulfur-based odorant may deteriorate due to, for example, the
reaction with mixed oxygen by the operation of the refrigeration cycle device over a
long period. For example, THT may be changed into an oxide such as tetramethylene
- 10 -
sulfoxide due to oxidative deterioration, and the odor may be reduced. Thus,
depending on the applications of the refrigeration cycle device, the concentration of the
sulfur-based odorant is preferably set high to sustain the effect of making the
refrigerant detectable by the sense of smell over a long period.
5 [0038] The sulfur-based odorant may be a compound that is not used as the odorant in
fuel gas, as long as it is a compound containing a sulfur element. For example,
hydrogen sulfide, carbonyl sulfide, and the like have an inherent unpleasant odor
similar to the aforementioned sulfur-based odorants, and can easily detect the leakage
of the refrigerant.
10 [0039] The refrigerant may further contain an odorant containing no sulfur. This is
because the odorant containing no sulfur hardly causes a corrosion reaction of metal in
the refrigerant circuit, as in the case of THT. Examples of the odorant containing no
sulfur include cyclohexene, acrylic acid esters, ammonia, amines, pyrazines, and
norbornenes. The refrigerant may further contain a compound having an inherent
15 odor as an odorant, other than these odorants containing no sulfur.
[0040]
In the present embodiment, the refrigeration cycle device includes a
compressor. The refrigerant passes through the inside of the compressor. The
compressor is filled with a refrigeration oil. The refrigeration oil contains a base oil.
20 [0041] Fig. 2 is a schematic cross-sectional view showing one example of the
compressor of the refrigeration cycle device according to the present embodiment.
Compressor 3 includes a shell 11, as shown in Fig. 2. Shell 11 includes a compression
mechanism 12 in the inside thereof, and includes an electric motor 13 which drives
compression mechanism 12. In addition, an inlet pipe 14 for allowing the refrigerant
25 to be flowed into the inside and a discharge pipe 15 for allowing the refrigerant to be
flowed to the outside are connected to shell 11. An accumulator 16 which separates
gas and liquid in the refrigerant and sends steam into inlet pipe 14 is connected to the
upstream side of inlet pipe 14.
[0042] The refrigerant that has passed through accumulator 16 flows from inlet pipe 14
- 11 -
into compression mechanism 12 in shell 11. The refrigerant that has flowed into
compression mechanism 12 is compressed to have high temperature and high pressure,
and is discharged from discharge pipe 15. That is, compression mechanism 12 is
configured to compress the refrigerant that has flowed from inlet pipe 14 into shell 11
5 and discharge the refrigerant from discharge pipe 15.
[0043] Compression mechanism 12 is a rotary-type compression mechanism composed
of a combination of a rolling piston 17 and a vane (not shown) and the like. The
refrigerant is compressed by changing the volume of a space surrounded by the inner
peripheral surface of a cylinder chamber 19 of a cylinder 18 and the outer peripheral
10 surface of rolling piston 17 and the vane (not shown) by an eccentric rotary motion of
rolling piston 17.
[0044] The compressed refrigerant is discharged from a discharge hole 21 of an upper
bearing 20 to a muffler space 22, and then discharged from a discharge hole 24 of a
discharge muffler 23 into shell 11. The discharged refrigerant passes through a gap in
15 electric motor 13 (such as a gap between an electric motor rotor 25 and an electric
motor stator 26 or a groove provided on the outer peripheral surface of the electric
motor stator 26), and is then discharged from discharge pipe 15 to the downstream side
of the refrigerant circuit 100.
[0045] Compressor 3 has a sliding part on the inside of compression mechanism 12.
20 For lubrication of the sliding part, a refrigeration oil is stored in an oil reservoir part 27,
which is located below compressor 3. The refrigeration oil stored in oil reservoir part
27 is supplied through an oil supply hole (not shown) provided in the shaft of a driving
shaft 28 to the sliding part in the inside of compression mechanism 12 by pumping
action. Since the refrigeration oil is brought into contact with the refrigerant in
25 compressor 3, a part of the refrigerant is dissolved in the refrigeration oil.
[0046] < Refrigeration oil>
Next, the refrigeration oil that fills the inside of the compressor for lubrication
in the present embodiment will be described. The refrigeration oil includes a base oil.
The base oil is at least one selected from the group consisting of an oxygen-containing
- 12 -
oil and a hydrocarbon oil. Examples of the oxygen-containing oil include
polyalkylene glycol (PAG), polyol ester (POE), and polyvinyl ether (PVE). Examples
of the hydrocarbon oil include polyalphaolefin (PAO), alkylbenzene (AB),
alkylnaphthalene (AN), and mineral oil.
5 [0047] Herein, the base oil is a component that lubricates the inside of the compressor
by the kinematic viscosity of the substance thereof. The base oil is preferably a
substance having a higher kinematic viscosity than the refrigerant, and more preferably
one having a kinematic viscosity at 40C of 5 mm2
/s or more and 250 mm2
/s or less.
The reason for this is as follows: when the base oil has a higher kinematic viscosity
10 than the refrigerant, the kinematic viscosity of the base oil is sufficient to lubricate the
sliding part of the compressor, and the cooling efficiency of the refrigeration cycle
device is prevented from being significantly reduced. The kinematic viscosity of the
base oil can be adjusted to be within the above range by changing the molecular
structure and the degree of polymerization of each base oil.
15 [0048] (Polyalkylene glycol)
PAG is a polymer of at least one selected from the group consisting of an
ethylene oxide group (EO group) and a propylene oxide group (PO group) and is
represented by the following chemical formula 1.
[0049]
20 [Formula 1]
[Chemical formula 1]
[0050] In the above chemical formula 1, m and n are each a numerical value of 0 or
more and representing the average of the number of EO groups and PO groups, and R1
and R2 25 are a hydrogen atom (H) or a hydrocarbon chain having one or more carbon
atoms. The arrangement of EO groups and PO groups may be any of a random
copolymer, an alternating copolymer, and a block copolymer.
[0051] In the above chemical formula 1, m and n preferably satisfy the relationships of
- 13 -
the following formulas (1) and (2). When the relationships of the following formulas
(1) and (2) are not satisfied, PAG may be solidified at low temperatures.
m + n  100 ... (1)
n/(m+n)  0.20 ... (2)
[0052] R1
and R2 5 are preferably a hydrocarbon chain having one or more carbon atoms.
When R1
and R2
are a hydrogen atom (H), the hygroscopicity of PAG increases, and
the moisture may be mixed.
[0053] PAG may be PAG having a single structure or a mixture of PAGs having
different structures. By using a mixture of PAGs having different structures, the
10 characteristics of the base oil can be adjusted.
[0054] (Polyol ester)
POE is an ester synthesized from a polyhydric alcohol and a fatty acid.
Examples of the method for synthesizing POE include, but are not particularly limited
to, dehydration condensation of a polyhydric alcohol and a fatty acid.
15 [0055] The fatty acid is a monovalent or divalent fatty acid. The fatty acid may be an
unsaturated fatty acid or a saturated fatty acid. The fatty acid may be a linear fatty
acid or a branched fatty acid. The fatty acid is preferably a saturated fatty acid. The
reason for this is as follows: the saturated fatty acid has high oxidation stability and
POE hardly causes deterioration by heat. The number of carbon atoms of fatty acid is
20 preferably 4 to 20. The reason for this is as follows: when the number of carbon
atoms of fatty acid is 4 to 20, the kinematic viscosity of POE is sufficient to lubricate
the sliding part of the compressor, and the cooling efficiency of the refrigeration cycle
device is prevented from being significantly reduced.
[0056] Examples of the monovalent fatty acid having 4 to 20 carbon atoms include
25 butanoic acid, 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, and icosanoic acid. These monovalent fatty acids may include all
isomers. These monovalent fatty acids may be linear or branched. More
- 14 -
specifically, the monovalent fatty acid may be a fatty acid having a branch on at least
one of -position and -position, and for example, 2-methylpropanoic acid, 2-
methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic
acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, and
5 2-ethylhexadecanoic acid are preferable, and 2-ethylhexanoic acid and 3,5,5-
trimethylhexanoic acid are further preferable. This is because the ester is excellent in
hydrolysis resistance due to the steric hindrance of the branch.
[0057] Examples of the divalent fatty acid having 4 to 20 carbon atoms include glutaric
acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.
10 [0058] The fatty acid may include fatty acids other than the fatty acid having 4 to 20
carbon atoms. Examples of fatty acids other than the fatty acid having 4 to 20 carbon
atoms include fatty acids having 21 to 24 carbon atoms, and specific examples thereof
include heneicosanoic acid, docosanoic acid, tricosanoic acid, and tetracosanoic acid.
These fatty acids may be linear or branched.
15 [0059] The fatty acid constituting POE may be any one of the aforementioned fatty
acids or may include two or more thereof.
[0060] The polyhydric alcohol is preferably a polyhydric alcohol having 2 to 6
hydroxyl groups. The reason for this is as follows: when the polyhydric alcohol is a
polyhydric alcohol having 2 to 6 hydroxyl groups, the kinematic viscosity of POE is
20 sufficient to lubricate the sliding part of the compressor, and the cooling efficiency of
the refrigeration cycle device is prevented from being significantly reduced. The
number of carbon atoms of the polyhydric alcohol is preferably 4 to 12, and more
preferably 5 to 10. As such a polyhydric alcohol, a hindered alcohol such as
neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, di25 (trimethylolpropane), tri-(trimethylolpropane), pentaerythritol, or dipentaerythritol is
preferable.
[0061] The polyhydric alcohol constituting POE may be any one of the aforementioned
polyhydric alcohols or may include two or more thereof.
[0062] POE may be a partial ester in which a part of the hydroxyl groups of a
- 15 -
polyhydric alcohol remains as hydroxyl groups without being esterified, a complete
ester in which all the hydroxyl groups are esterified, or a mixture of a partial ester and a
complete ester.
[0063] When the fatty acid is a divalent fatty acid, both carboxyl groups may be
5 esterified or only one carboxyl group may be esterified. When both carboxyl groups
of a divalent fatty acid are esterified, one carboxyl group may not be an ester with a
polyhydric alcohol, but may be an ester with a monovalent alcohol. The monovalent
alcohol preferably has 1 to 20 carbon atoms.
[0064] POE may be not only POE having a single structure, but also a mixture of POEs
10 having different structures. By using a mixture of POEs having different structures,
the characteristics of the base oil can be controlled.
[0065] (Polyvinyl ether)
PVE is a compound obtained by polymerization reaction of a vinyl ether
compound and has a polyvinyl ether structure shown in the following chemical formula
15 2.
[0066]
[Formula 2]
[Chemical formula 2]
[0067] In the above chemical formula 2, R1
, R2
, and R3 20 are each a hydrogen atom or a
hydrocarbon group having 1 to 8 carbon atoms, and may be the same as one another or
may be different from one other. R4
is a hydrocarbon group having 2 to 10 carbon
atoms, R5
is a hydrocarbon group having 1 to 10 carbon atoms, and k is a numerical
value of 0 or more and 10 or less and represents an average of the number of R4O. R1
- 16 -
to R5
for each constitutional unit may be the same or may be different. When there is
a plurality of R4O, the plurality of R4O may be the same or different from one another.
n is a numerical value of two or more and represents an average of the number of
constitutional units of the polyvinyl ether structure.
[0068] Examples of R1
, R2
, and R3 5 include a hydrogen atom (H), alkyl groups such as a
methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group,
an isobutyl group, a sec-butyl group, a tert-butyl group, various pentyl groups, various
hexyl groups, various heptyl groups, and various octyl groups; cycloalkyl groups such
as a cyclopentyl group, a cyclohexyl group, various methylcyclohexyl groups, various
10 ethylcyclohexyl groups, and various dimethylcyclohexyl groups; aryl groups such as a
phenyl group, various methylphenyl groups, various ethylphenyl groups, and various
dimethylphenyl groups; and arylalkyl groups such as a benzyl group, various
phenylethyl groups, and various methylbenzyl groups. Among them, a hydrogen
atom (H) or a hydrocarbon group having 1 to 5 carbon atoms is preferable, and a
15 hydrogen atom (H) or a hydrocarbon group having 1 to 3 carbon atoms is more
preferable.
[0069] Examples of R4
include hydrocarbon groups such as an ethylene group, a
phenylethylene group, a 1,2-propylene group, a 2-phenyl-1,2-propylene group, a 1,3-
propylene group, various butylene groups, various pentylene groups, various hexylene
20 groups, various heptylene groups, various octylene groups, various nonylene groups,
and various decylene groups; cycloaliphatic groups that have two binding sites on a
cycloaliphatic hydrocarbon, such as cyclohexane, methylcyclohexane,
ethylcyclohexane, dimethylcyclohexane, and propylcyclohexane; aromatic hydrocarbon
groups such as various phenylene groups, various methylphenylene groups, various
25 ethylphenylene groups, various dimethylphenylene groups, and various naphthylenes;
alkyl aromatic groups that have a monovalent binding site on each of the alkyl group
moiety and the aromatic moiety of an alkyl aromatic hydrocarbon, such as toluene,
xylene, and ethylbenzene; alkyl aromatic groups that have a binding site on an alkyl
group moiety of a polyalkyl aromatic hydrocarbon, such as xylene and diethylbenzene.
- 17 -
Among these for R4
, an alkyl group having 2 to 4 carbon atoms is preferable. k is
preferably a numerical value of 0 or more and 5 or less.
[0070] Examples of R5
include alkyl groups such as a methyl group, an ethyl group, an
n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl
5 group, a tert-butyl group, various pentyl groups, various hexyl groups, various heptyl
groups, various octyl groups, various nonyl groups, and various decyl groups;
cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, various
methylcyclohexyl groups, various ethylcyclohexyl groups, various propylcyclohexyl
groups, and various dimethylcyclohexyl groups; aryl groups such as a phenyl group,
10 various methylphenyl groups, various ethylphenyl groups, various dimethylphenyl
groups, various propylphenyl groups, various trimethylphenyl groups, various
butylphenyl groups, and various naphthyl groups; and arylalkyl groups such as a benzyl
group, various phenylethyl groups, various methylbenzyl groups, various phenylpropyl
groups, and various phenylbutyl groups. Among these for R5
, a hydrocarbon group
15 having 8 or less carbon atoms is preferable. When k is 0, an alkyl group having 1 to 6
carbon atoms is more preferable, and when k is 1 or more, an alkyl group having 1 to 4
carbon atoms is more preferable.
[0071] PVE may be not only PVE having a single structure, but also a mixture of PVEs
having different structures. By using a mixture of PVEs having different structures,
20 the characteristics of the base oil can be controlled.
[0072] (Polyalpha olefin)
Examples of PAO include one obtained by polymerizing a hydrocarbon
monomer having an olefinic double bond. Examples of the hydrocarbon monomer
having an olefinic double bond include ethylene, propylene, various butenes, various
25 pentenes, various hexenes, various heptenes, various octenes, diisobutylene,
triisobutylene, styrene, -methylstyrene, and various alkyl-substituted styrenes. The
hydrocarbon monomers having an olefinic double bond may be used singly or in
combination of two or more.
[0073] PAO may be not only PAO having a single structure, but also a mixture of
- 18 -
PAOs having different structures. By using a mixture of PAOs having different
structures, the characteristics of the base oil can be controlled.
[0074] (Alkylbenzene)
AB is a compound in which at least one of the hydrogen atoms of benzene is
5 replaced with a hydrocarbon group. AB is preferably one in which one to four of the
hydrogen atoms are each replaced with a hydrocarbon group, and more preferably one
in which one or two of the hydrogen atoms are each replaced with a hydrocarbon
group. This is because stability and availability are excellent. As the hydrocarbon
group, a hydrocarbon group having 1 to 19 carbon atoms is preferable. The reason for
10 this is as follows: when the hydrocarbon group is a hydrocarbon group having 1 to 19
carbon atoms, the kinematic viscosity of AB is sufficient to lubricate the sliding part of
the compressor, and the cooling efficiency of the refrigeration cycle device is prevented
from being significantly reduced.
[0075] Examples of the hydrocarbon group having 1 to 19 carbon atoms include a
15 methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl
group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group,
a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl
group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an eicosyl
group. These hydrocarbon groups may include all isomers. These hydrocarbon
20 groups may be linear or branched.
[0076] AB may be not only AB having a single structure, but also a mixture of ABs
having different structures. By using a mixture of ABs having different structures, the
characteristics of the base oil can be controlled.
[0077] (Alkylnaphthalene)
25 AN is a compound in which at least one of the hydrogen atoms (H) of
naphthalene is replaced with a hydrocarbon group. AN is preferably one in which one
to four of the hydrogen atoms (H) are each replaced with a hydrocarbon group, and
more preferably one in which one to three of the hydrogen atoms (H) are each replaced
with a hydrocarbon group. This is because stability and availability are excellent.
- 19 -
The hydrocarbon group is preferably a hydrocarbon group having 1 to 19 carbon atoms.
The reason for this is as follows: when the hydrocarbon group is a hydrocarbon group
having 1 to 19 carbon atoms, the kinematic viscosity of AN is sufficient to lubricate the
sliding part of the compressor, and the cooling efficiency of the refrigeration cycle
5 device is prevented from being significantly reduced.
[0078] Examples of the hydrocarbon group having 1 to 19 carbon atoms include a
methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl
group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group,
a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl
10 group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an eicosyl
group. These hydrocarbon groups may include all isomers. These hydrocarbon
groups may be linear or branched.
[0079] AN may be not only AN having a single structure, but also a mixture of ANs
having different structures. By using a mixture of ANs having different structures, the
15 characteristics of the base oil can be controlled.
[0080] (Mineral oil)
Mineral oil is a lubricating oil that can be obtained by separation and
purification of crude oil. Mineral oil includes paraffinic mineral oil and naphthenic
mineral oil, and the mineral oil may be either paraffinic mineral oil or naphthenic
20 mineral oil, or may be a mixture thereof.
[0081] (Lubricant additive)
The refrigeration oil may contain an antioxidant, an acid scavenger, or an
extreme-pressure agent (anti-wear agent) as a lubricant additive.
[0082] Examples of the antioxidant include phenol-based antioxidants such as 2,6-di25 tert-butyl-4-methyl phenol, 2,6-di-tert-butyl-4-ethylphenol, and 2,2'-methylenebis(4-
methyl-6-tert-butylphenol), and amine-based antioxidants such as phenyl--
naphthylamine and N,N'-di-phenyl-p-phenylenediamine. The antioxidant not only
suppresses the deterioration of the refrigeration oil, but also has the effect of
suppressing the oxidative deterioration of the sulfur-based odorant.
- 20 -
[0083] The content of the antioxidant is preferably 0.05% by mass or more and 2% by
mass or less, and more preferably 0.2% by mass or more and 1% by mass or less, based
on the refrigeration oil. When the content of the antioxidant is less than 0.05% by
mass based on the refrigeration oil, the effect of the antioxidant may not be obtained.
5 When the content of the antioxidant is more than 2% by mass based on the refrigeration
oil, the kinematic viscosity of the refrigeration oil may be reduced or the deteriorated
antioxidant may block the refrigerant circuit as an impurity.
[0084] Examples of the acid scavenger include epoxy compounds such as phenyl
glycidyl ether, alkyl glycidyl ester, alkyl glycidyl ether, alkylene glycol glycidyl ether,
10 cyclohexene oxide, -olefin oxide, and epoxidized soybean oil. The acid scavenger is
preferably alkyl glycidyl ester, alkyl glycidyl ether, or -olefin oxide. The acid
scavenger captures the acid generated by the deterioration of organic materials (such as
an insulating film and a sealing film) that are present in the refrigeration oil and the
refrigerant circuit, and thus has the effect of suppressing the deterioration of the sulfur15 based odorant caused by acid.
[0085] The content of the acid scavenger is preferably 0.05% by mass or more and
10% by mass or less, and more preferably 0.1% by mass or more and 10% by mass or
less, based on the refrigeration oil. When the content of the acid scavenger is less
than 0.05% by mass based on the refrigeration oil, the effect of the acid scavenger may
20 not be obtained. When the content of the acid scavenger is more than 10% by mass
based on the refrigeration oil, the kinematic viscosity of the refrigeration oil may be
reduced or the deteriorated acid scavenger may block the refrigerant circuit as an
impurity.
[0086] Examples of the extreme-pressure agent (anti-wear agent) include phosphorus25 based extreme-pressure agents such as phosphate esters, thiophosphate esters, acidic
phosphate esters, phosphite esters, acidic phosphite esters and amine salts thereof.
The extreme-pressure agent (anti-wear agent) is preferably a phosphate ester, a
thiophosphate ester, or a mixture thereof. Specifically, tricresyl phosphate (O=P-
(OC7H7)3), triphenyl phosphorothioate (S=P-(OC6H5)3), triphenyl phosphate (O=P-
- 21 -
(OC6H5)3), derivatives thereof, or a mixture thereof is preferable. Since the extremepressure agent reduces the friction of the sliding part of the compressor, it has the effect
of suppressing the deterioration of the sulfur-based odorant caused by friction heat.
[0087] The content of the extreme-pressure agent is preferably 0.05% by mass or more
5 and 5% by mass or less, and more preferably 0.1% by mass or more and 4% by mass or
less, based on the refrigeration oil. When the content of the extreme-pressure agent is
less than 0.05% by mass based on the refrigeration oil, the effect of the extremepressure agent may not be obtained. When the content of the extreme-pressure agent
is more than 5% by mass based on the refrigeration oil, metal may be corroded by the
10 extreme-pressure agent, the kinematic viscosity of the refrigeration oil may be reduced,
or the deteriorated extreme-pressure agent may block the refrigerant circuit as an
impurity.
[0088] The refrigeration oil may contain an oxygen scavenger. Examples of the
oxygen scavenger include sulfur-containing aromatic compounds such as 4,4'-thiobis(3-
15 methyl-6-tert-butylphenol), diphenyl sulfide, dioctyl diphenyl sulfide, dialkyl
diphenylene sulfide, benzothiophene, dibenzothiophene, phenothiazine,
benzothiapyran, thiapyran, thianthrene, dibenzothiapyran, and diphenylene disulfide;
aliphatic unsaturated compounds such as various olefins, diene, and triene; and cyclic
terpenes having an unsaturated bond, such as -pinene, -pinene, limonene, and
20 phellandrene. The oxygen scavenger is preferably an aliphatic unsaturated compound
or a cyclic terpene having an unsaturated bond. The oxygen scavenger not only
suppresses the oxidative deterioration of the refrigeration oil, but also has the effect of
suppressing the oxidation deterioration of the sulfur-based odorant.
[0089] The content of the oxygen scavenger is preferably 0.05% by mass or more and
25 5% by mass or less, and more preferably 0.1% by mass or more and 3% by mass or
less, based on the refrigeration oil. When the content of the oxygen scavenger is less
than 0.05% by mass based on the refrigeration oil, the effect of the oxygen scavenger
may not be obtained. When the content of the oxygen scavenger is more than 5% by
mass based on the refrigeration oil, the kinematic viscosity of the refrigeration oil may
- 22 -
be reduced or the deteriorated oxygen scavenger may block the refrigerant circuit as an
impurity.
[0090] (Others)
The refrigeration oil may contain a fluorescent agent, a colorant, or the like so
5 as to visually detect the refrigerant and the refrigeration oil. Preferably, the amount of
the fluorescent agent and colorant added is not more than the saturated solubility of the
refrigeration oil so as not to cause precipitation at low temperatures.
[0091] When moisture is contained in the refrigeration oil, the deterioration of the
refrigerant, refrigeration oil, metals in the refrigerant circuit, organic materials (such as
10 polyester) in the refrigerant circuit, and the others may be promoted, and thus, it is
necessary to control the amount of the moisture contained in the refrigeration oil to be
filled so as to be 300 ppm by mass or less, and preferably 100 ppm by mass or less.
[0092] The refrigeration cycle device has been described above with reference to a
mode in which a rotary compressor is used as compressor 3, but the refrigeration cycle
15 device is not limited thereto. For example, a low-pressure shell or high-pressure shell
scroll compressor, a screw compressor, or the others may be used as compressor 3.
[0093] (Ratio of number of oxygen atoms to number of carbon atoms in molecular
structure of base oil)
The ratio of the number of oxygen atoms (O) to the number of carbon atoms (C)
20 in the molecular structure of the base oil (O/C ratio) (hereinafter, also simply referred
to as the "O/C ratio") is less than 0.50. When the O/C ratio is less than 0.50, polarity
due to polarization is low, the intermolecular interaction between the base oil and the
sulfur-based odorant is small, the amount of the sulfur-based odorant dissolved in the
base oil is small, and the refrigerant released from the refrigerant circuit is recognizable
25 by the sense of smell. The O/C ratio is preferably 0.43 or less, and more preferably
0.39 or less. The lower limit of the O/C ratio is not particularly limited, and may be 0
like the hydrocarbon oil.
[0094] Other refrigeration oils may be mixed in the refrigeration oil, as long as the O/C
ratio in the molecular structure of PAG is lower than that of PAG. Examples of other
- 23 -
refrigeration oils include polyol ester, polyvinyl ether, alkylbenzene, alkylnaphthalene,
mineral oil, poly -olefin, or a mixture thereof. Since polyol ester and polyvinyl ether
have low miscibility with a hydrocarbon having 1 to 4 carbon atoms like PAG, the
amount of the refrigerant dissolved is small and the amount of the refrigerant to be
5 filled can be reduced. Accordingly, polyol ester and polyvinyl ether are preferable.
[0095] As long as the O/C ratio is less than 0.50, the base oil may not have a single
structure, and may be a mixture of base oils having different structures. The O/C ratio
of the mixture can be calculated by determining the weighted average of the O/C ratio
from the molar ratio of each base oil to the whole base oil. For example, in the case of
10 a base oil in which POE (a completely esterified product of pentaerythritol and 2-
ethylhexanoic acid) having an O/C ratio of 8/37 is mixed with PVE (a polymer in
which R1
, R2
, and R3
are hydrogen atoms (H), k is 0, R5
is an ethyl group, and n is 10 in
the aforementioned chemical formula 2) having an O/C ratio of 1/4 at a molar ratio of
1:1, the O/C ratio is 8/37  0.5 + 1/4  0.5 = 69/236.
15 [0096] The sulfur-based odorant contained in the refrigerant is a polar molecule having
a dipole moment due to deviation of charge, in a molecule. For example, according to
the literature (J. Am. Chem. Soc., Vol. 61, P. 1769-1780, 1939), the magnitude of the
dipole moment of THT is 1.87 D. Since the dipole moments of H2O and CH3OH,
which are considered as polar solvents, are 1.9 D and 1.7 D, respectively, THT is a
20 polar molecule having a large dipole moment. In addition, according to the literature
(J. Chem. Phys., Vol. 1, P. 337-340, 1933), it is reported that the dipole moments of
mercaptans are about 1.3 D to 1.5 D, and that the dipole moments of sulfides are about
1.4 D to 1.58 D. Thus, they are polar molecules like THT.
[0097] As described above, since the sulfur-based odorant is a polar molecule, the
25 sulfur-based odorant is dissolved in the base oil by an electrical interaction with polar
groups (moieties having a bond between C and O) of the base oil. Since a base oil
having a large O/C ratio has a large number of polar groups in the molecular structure,
a strong electrical interaction occurs between the polar groups and the sulfur-based
odorant. Consequently, when a base oil having a large O/C ratio is mixed with the
- 24 -
sulfur-based odorant, the sulfur-based odorant is hardly released.
[0098] Since the hydrocarbon having 1 to 4 carbon atoms that is the main component
functioning as the refrigerant does not have a polar group in the molecule, it is a
nonpolar molecule having a significantly small bias of charge. For example,
5 according to the literature (J. Chem. Phys., Vol. 33, No. 5, P. 1514-1518, 1960), the
dipole moment of R-290 is a value as small as 0.083 D, and R-290 is thus a nonpolar
molecule. According to the literature (J. Chem. Phys., Vol. 27, No. 4, P. 868-873,
1957), the dipole moment of R-1270 is 0.364 D, and according to another literature (J.
Chem. Phys., Vol. 29, No. 4, P. 914-920, 1958), the dipole moment of R-600a is 0.132
10 D. Thus, since the hydrocarbon having 1 to 4 carbon atoms does not have a polar
group in the molecule, it is a nonpolar molecule having a significantly small bias of
charge.
[0099] Since the hydrocarbon having 1 to 4 carbon atoms is a nonpolar molecule as
described above, the solubility of the sulfur-based odorant in the hydrocarbon having 1
15 to 4 carbon atoms is low. When the hydrocarbon having 1 to 4 carbon atoms is
dissolved in the base oil, the solubility of the sulfur-based odorant in the base oil is
reduced. Since a base oil having a larger O/C ratio has a larger number of polar
groups in the molecular structure, the solubility of the hydrocarbon having 1 to 4
carbon atoms, which is a nonpolar molecule, is low. Since a base oil having a smaller
20 O/C ratio has higher solubility of the hydrocarbon having 1 to 4 carbon atoms, a large
number of hydrocarbons having 1 to 4 carbon atoms is dissolved in the base oil.
Thus, the solubility of the sulfur-based odorant in the base oil is lower, and the sulfurbased odorant is more easily released.
[0100] For example, even when a base oil having an O/C ratio of 0.50 or more is mixed
25 with another base oil so as to reach a weighted average of the O/C ratio less than 0.50,
the polarity of the whole base oil is reduced, the amount of the sulfur-based odorant
dissolved is small, and the refrigerant released from the refrigerant circuit is
recognizable by the sense of smell.
[0101]
- 25 -
The difference between the HSP distance between the base oil and the sulfurbased odorant and the HSP distance between the base oil and the hydrocarbon having 1
to 4 carbon atoms ([the HSP distance between the base oil and the sulfur-based
odorant] - [the HSP distance between the base oil and the hydrocarbon having 1 to 4
5 carbon atoms]) is -2.0 or more. Hereinafter, the HSP distance between the base oil
and the sulfur-based odorant is sometimes referred to as "the HSP distance to the
sulfur-based odorant", and the HSP distance between the base oil and the hydrocarbon
having 1 to 4 carbon atoms is sometimes referred to as "the HSP distance to the
hydrocarbon", respectively.
10 [0102] Herein, "HSP" means "Hansen Solubility Parameter", and is a value used to
predict the solubility of substances based on the idea that "substances having similar
intramolecular interactions are easily dissolved in each other". Specifically, HSP is
represented as a three-dimensional vector by three parameters (dD, dP, and dH), which
are a dispersion term, a polar term, and a hydrogen bond term, respectively. As for
15 two substances, the solubility is higher, as their vectors (dD, dP, and dH) are similar.
[0103] The HSP of a substance can be cited from the database and calculated from the
molecular structure by using computer software, HSPiP (Hansen Solubility Parameter
in Practice) Ver. 5.3.
[0104] The "HSP distance" is the distance between HSP values of two substances, and
20 is a value indicating the similarity of vectors ((dD1, dP1, and dH1) and (dD2, dP2, and
dH2)) of two substances. Specifically, it is determined by the following formula (3)
based on the above three parameters (dD, dP, and dH). With respect to two
substances whose HSP distances are to be calculated, dD, dP, and dH of one substance
are represented by dD1, dP1, and dH1, and dD, dP, and dH of another substance are
25 represented by dD2, dP2, and dH2, in the following formula (3). As for two
substances, the solubility is lower, as the HSP distance is larger.
HSP distance = {4  (dD1-dD2)2
+ (dP1-dP2)2
+ (dH1-dH2)2}
0.5 ... (3)
[0105] As the amount of the sulfur-based odorant dissolved in the base oil is smaller,
the amount of the sulfur-based odorant that circulates in the refrigerant circuit is larger,
- 26 -
and the refrigerant released from the refrigerant circuit is recognizable by the sense of
smell. In addition, as the amount of the hydrocarbon having 1 to 4 carbon atoms
dissolved in the base oil is larger, the amount of the sulfur-based odorant dissolved in
the base oil is smaller for the reason described below, and as a result, the amount of the
5 sulfur-based odorant circulates in the refrigerant circuit is larger, so that the refrigerant
released from the refrigerant circuit is recognizable by the sense of smell. Namely, as
the difference between the HSP distance to the sulfur-based odorant and the HSP
distance to the hydrocarbon ([the HSP distance to the sulfur-based odorant] - [the HSP
distance to the hydrocarbon]) is larger, the amount of the sulfur-based odorant
10 dissolved in the base oil is smaller, a larger amount of the sulfur-based odorant is
contained in the refrigerant released from the refrigerant circuit, and the refrigerant
released from the refrigerant circuit is recognizable by the sense of smell.
[0106] When the difference between the HSP distance to the sulfur-based odorant and
the HSP distance to the hydrocarbon is -2.0 or more, the amount of the sulfur-based
15 odorant dissolved in the base oil is sufficiently small, and the refrigerant released from
the refrigerant circuit is recognizable by the sense of smell. The difference between
the HSP distance to the sulfur-based odorant and the HSP distance to the hydrocarbon
is preferably -0.5 or more, and more preferably -0.4 or more. The upper limit of the
difference between the HSP distance to the sulfur-based odorant and the HSP distance
20 to the hydrocarbon is not particularly limited, but the difference may be 10 or less, or
5.0 or less.
EXAMPLES
[0107] Hereinafter, the present disclosure will be described in detail with reference to
Examples, but the present disclosure is not limited to these Examples.
25 [0108]
Refrigerant gas in which a refrigerant, a sulfur-based odorant, and a
refrigeration oil were mixed was prepared under the conditions shown in Table 1 to
evaluate the amount of the sulfur-based odorant released with the refrigerant when the
refrigerant, the sulfur-based odorant, and the refrigeration oil were mixed. As the
- 27 -
refrigeration oil, one including PAG as the base oil was used. In the base oil, m was 7
(a value rounded off to the nearest integer), n was 36 (a value rounded off to the nearest
integer), and R1
and R2
were CH3, in the aforementioned chemical formula 1. The
concentration of the sulfur-based odorant (THT) in the refrigerant gas is shown in
5 Table 2.
[0109]
[Table 1]
[0110]
10 [Table 2]
[0111] The above refrigerant gas was enclosed in a test container, which was shaken at
140C to stir the refrigerant gas, and then, the test container was allowed to stand still
at 25C. 24 hours after the start of still standing, a tedlar bag (1-2711-05
15 manufactured by AS ONE Corporation) was connected to the discharge port of the test
- 28 -
container, and the refrigerant gas was collected at 25C. For the collected refrigerant
gas, the concentration of THT was measured by using a gas chromatography mass
spectrometer (JMS-K9 manufactured by JEOL Ltd.).
[0112] The relationship between the concentration of THT in the enclosed refrigerant
5 gas and the concentration of THT in the collected refrigerant gas is shown in Fig. 3.
The concentration of THT in the collected refrigerant gas was increased in a linear
relation in a range of the concentration of THT in the enclosed refrigerant gas from 2.3
ppm by mass to 987 ppm by mass, and increased in a linear relation with a larger
inclination in a range from 987 ppm by mass to 2,230 ppm by mass. The expression
10 of the approximate line in Fig. 3 was y = 0.047x in the range of the concentration of
THT from 2.3 ppm by mass to 987 ppm by mass, and y = 1.66x - 774 in the range from
987 ppm by mass to 2,230 ppm by mass. Specifically, in the range of the
concentration of THT in the enclosed refrigerant gas from 2.3 ppm by mass to 987 ppm
by mass, the amount of THT released with R-290 was about 4.7% of the enclosed THT,
15 and the remaining, about 95.3%, kept in a state dissolved in PAG and was not released
as the gas.
[0113] Even when THT was mixed in R-290 as described above, THT was dissolved in
PAG, so that only a part of THT in the enclosed refrigerant gas was released with R290, and the refrigerant was demonstrated to be hardly detectable by the sense of smell
20 when the refrigerant was released from the refrigeration cycle device.
[0114]
Each sample gas in which air was mixed with a sulfur-based odorant (THT) was
prepared under the conditions shown in Table 3 to quantitatively evaluate the
relationship between the concentration of the sulfur-based odorant in air and the
25 intensity of the odor. The concentration of THT in the sample gas is shown in Table
4.
[0115]
- 29 -
[Table 3]
[0116]
[Table 4]
5
[0117] The odor index (equivalent value) of the above sample gas was measured.
Herein, the "odor index" is a numerical expression for the degree of odor using the
human sense of smell, and is a value obtained by multiplying the common logarithm of
the odor concentration of an odor component (the concentration of the odor component
10 when the odor is diluted with air to the extent that the odor can no longer be sensed by
the human sense of smell) by 10. The "odor index (equivalent value)" is a numerical
value corresponding to the odor index and obtained by the measurement with an odor
identification device. In the measurement, nitrogen (N2) was used as the carrier gas,
and the dilution factor of the sample with the carrier gas was set to 100.
15 [0118] The relationship between the concentration of THT in the sample gas and the
odor index (equivalent value) is shown in Fig. 4. The concentration of THT in the
sample gas and the odor index (equivalent value) were in a logarithmic function
relationship. This means that the results following the rule of Weber-Fechner, which
- 30 -
represents the relationship between the concentration of an odor substance and the
intensity of the odor, were obtained. In the present test, high purity air was used as
the gas for diluting THT. However, also in the case where THT is diluted with R-290,
the same correlation is considered to be obtained for the concentration of THT and the
5 odor index (equivalent value) because R-290 is odorless.
[0119] The odor index has a relationship with the odor intensity in the 6-step odor
intensity display method as shown in Table 5. The concentrations of THT shown in
Table 5 were the results of the determination of the concentration of THT
corresponding to an odor intensity of 2.5 to 3.5, based on the relationship between the
10 concentration of THT and the odor index (equivalent value) in Fig. 4.
[0120]
[Table 5]
[0121] To recognize the refrigerant by the sense of smell, the presence of the sulfur15 based odorant contained in the refrigerant is needed to be recognized. Accordingly,
the odor intensity of the refrigerant is preferably 2 (a weak odor whose odor source can
be seen) or more, and more preferably 3 (an odor is sensed with ease) or more.
[0122] The refrigerant released from the refrigerant circuit into the atmosphere is
diluted with air, and the concentration of THT is reduced. The international standard
20 ISO-13734 relating to the odorization treatment of natural gas states that the natural gas
is needed to have an odor even when being diluted to 20% by volume of the lower
flammability limit (LFL). The LFL of R-290 is 21,000 ppm by volume in ISO-817,
and 20% of the LFL is thus 4,200 ppm by volume.
[0123] As for the odorization treatment of gas, the Japanese ordinance on the
- 31 -
odorization treatment of gas (an ordinance that establishes technical standards of gas
facilities (Ordinance of the Ministry of International Trade and Industry No. 111 of
2000)) states that it is necessary to enable "the presence or absence of an odor to be
sensed when the mixed volume ratio of gas to the air is 1/1,000". Accordingly, when
5 the concentration of R-290 is diluted to 1,000 ppm by volume in the air, R-290 needs to
be recognized by the odor, and thus, a stronger odorization treatment than ISO-13734 is
required.
[0124] In mixed gas of the air and THT in which 1,000 ppm of R-290 is contained,
THT needs to be contained in a concentration of 2.1 ppb by volume or more in order to
10 make the odor intensity of the mixed gas 2 or more. That is, in the mixed gas of R290 and THT, 2.1 ppm by volume (4.2 ppm by mass) or more of THT is needed to be
contained.
[0125] To make the odor intensity of the mixed gas to 3 or more, THT needs to be
contained in a concentration of 4.1 ppb by volume or more. That is, in the mixed gas
15 of R-290 and THT, 4.1 ppm by volume (8.2 ppm by mass) or more of THT needs to be
contained.
[0126] As described above, the concentration of THT needed to recognize the
refrigerant by the sense of smell was demonstrated by quantitatively clarifying the
relationship between the concentration of THT in the sample gas and the intensity of
20 the odor.
[0127] In the results of evaluation test 1 shown in Fig. 3, the concentrations of THT to
make the THT concentrations in the released refrigerant gas 4.2 ppm by mass and 8.2
ppm by mass are 90 ppm by mass and 176 ppm by mass, respectively. Thus, when
PAG used in evaluation test 1 is used in the refrigeration cycle device, the refrigerant
25 gas released from the refrigerant circuit diluted to 1/1,000 in the air is recognizable by
the sense of smell, as long as the concentration of THT in the refrigerant is 90 ppm by
mass or more.
[0128] Meanwhile, when the odor intensity of the air containing the refrigerant gas is 5
(intense odor), the released odor of the refrigerant gas is too unpleasant. In the results
- 32 -
of evaluation test 1 shown in Fig. 3, the concentration of THT to make the
concentration of THT in the released refrigerant 77 ppm by volume (154 ppm by mass)
is 514 ppm by volume (1,026 ppm by mass). In other words, when PAG shown in
Table 2 is used in the refrigeration cycle device, the refrigerant gas released from the
5 refrigerant circuit diluted to 1/1,000 in the air does not become a too unpleasant odor,
as long as the THT concentration in the refrigerant is less than 1,026 ppm by mass.
[0129] However, THT may deteriorate due to, for example, the reaction with mixed
oxygen by the operation of the refrigeration cycle device over a long period. Thus,
depending on the applications of the refrigeration cycle device, the concentration of
10 THT is preferably set high to sustain the effect of making the refrigerant detectable by
the sense of smell over a long period.
[0130] The correlation between the concentration of the sulfur-based odorant and the
odor index following the rule of Weber-Fechner is not limited to THT. Thus, with
respect to any kind of sulfur-based odorants, the concentration at which a sufficient
15 odor can be obtained can be determined by the aforementioned method.
[0131]
To demonstrate the influence on the results of evaluation test 1 by the molecular
structure of the refrigeration oil, each refrigerant gas in which R-290 containing the
sulfur-based odorant (THT) serving as the refrigerant was mixed with a refrigeration oil
20 containing PAG shown in Table 6 as the base oil was prepared under the conditions
shown in Table 7. The concentration of THT in the refrigerant was 600 ppm by mass
so that the odor intensity of the refrigerant described in Table 5 was 3.
[0132]
- 33 -
[Table 6]
[0133]
[Table 7]
5
[0134] The values for the molecular structure of PAG shown in Table 6 were
determined based on the number average degree of polymerization of the composition
of each PAG, and m and n are values rounded off to the nearest integer. The O/C
ratio is a value obtained by rounding off the ratio of the number of oxygen atoms (O) to
10 the number of carbon atoms (C) in the molecular structure to the second decimal place
- 34 -
and represented by two significant figures.
[0135] The above refrigerant gas was enclosed in a test container, which was shaken at
140C to stir the refrigerant gas, and then, the test container was allowed to stand still
at 25C. 24 hours after the start of still standing, a tedlar bag (1-2711-05
5 manufactured by AS ONE Corporation) was connected to the discharge port of the test
container, and the refrigerant gas was collected at 25C. The collected refrigerant gas
was diluted to 1/1,000 with high purity air (ZERO-A manufactured by Sumitomo Seika
Chemicals Company, Limited.), and then, the evaluation of the odor intensity was
carried out by the odor sensory test method with reference to the literature (Journal of
10 Japan Society of Air Pollution, Vol. 27, No. 2, P. A17-A24, 1992). The results of the
odor intensity of the collected refrigerant gas represented by the 6-level odor intensity
display method are shown in Table 8. The evaluation was such that the odor intensity
of 2 or more was rated as "A", and the odor intensity of 1 or less was rated as "B".
The evaluation was carried out by 5 examiners.
15 [0136]
[Table 8]
[0137] As a result of the above evaluation, the refrigerant gas in which PAG (No. 3 to
13) having an O/C ratio of less than 0.50 was mixed had a sufficiently small amount of
20 THT dissolved in PAG, as described above, and had an odor in the range of the odor
- 35 -
intensity of 2 (a weak odor whose odor source can be seen) to the odor intensity of 4
(strong odor), and THT was demonstrated to be contained in the refrigerant gas. The
refrigerant gas in which PAG (No. 1 and 2) having an O/C ratio of 0.50 or more was
mixed had an odor in the range of the odor intensity of 0 (odorless) to the odor intensity
5 of 1 (an odor is sensed with difficulty), and THT was not demonstrated to be contained
in the refrigerant gas.
[0138] These results mean that the amount of THT that is dissolved in PAG and not
released with the refrigerant gas can be explained by the ratio of the polar groups
(moieties having a bond between C and O) in the molecular structure of PAG.
10 [0139] As described above, since THT is a polar molecule having a dipole moment of
1.87 D, THT is incorporated into the molecular chain of PAG by an electrical
interaction with polar groups (moieties having a bond between C and O) of PAG and
dissolved therein. Since PAG having a large O/C ratio has a large number of polar
groups in the molecular structure, a strong electrical interaction of incorporating THT
15 occurs. Consequently, when PAG having a large O/C ratio is mixed with THT, THT
is hardly released.
[0140] As described above, since R-290 is a nonpolar molecule having a dipole
moment of 0.083 D, the solubility of THT in R-290 is low, and when R-290 is
dissolved in PAG, the solubility of THT in PAG is reduced. Since PAG having a
20 large O/C ratio has a large number of polar groups in the molecular structure, the
solubility of R-290, which is a nonpolar molecule, is low. Since PAG having a low
O/C ratio has high solubility of R-290, a larger amount of R-290 is dissolved in PAG.
Accordingly, that the solubility of THT in PAG is lower and THT is more easily
released.
25 [0141] It is considered that, when the O/C ratio is less than 0.50, the proportion of the
polarized group of atoms in the molecular structure of PAG becomes half or less and
that the effect of increasing the amount of THT released is achieved. Thus, the O/C
ratio is preferably less than 0.50.
[0142] From the above results, to circulate THT with R-290 in the refrigerant circuit by
- 36 -
suppressing the dissolution of THT in PAG, PAG having an O/C ratio of less than 0.50
is preferably used.
[0143] From the results shown in evaluation test 1, the relationship of the O/C ratio and
the odor intensity is considered to be obtained also when a hydrocarbon having 1 to 4
5 carbon atoms other than R-290, a sulfur-based odorant other than THT, and a
refrigeration oil other than PAG are used. This is because the amount of the sulfurbased odorant dissolved in the refrigeration oil is determined by the polarity of the base
oil, regardless of the type of hydrocarbon having 1 to 4 carbon atoms, sulfur-based
odorant, and base oil. Since hydrocarbons having 1 to 4 carbon atoms other than R10 290 are nonpolar molecules having a small dipole moment like R-290, as described
above, the same results as R-290 are considered to be obtained. Since sulfur-based
odorants other than THT are polar molecules having dipole moments similar to THT,
as described above, the same results are considered to be obtained. Although the
difference in the type of base oil generates the difference in the O/C ratio, it does not
15 change the principle of the dissolution of the sulfur-based odorant.
[0144]
The results of evaluation test 3 demonstrated that use of PAG as the base oil
having a low O/C ratio enabled reduction in the solubility of THT in PAG and release
of THT with R-290. However, the difference in the odor intensities of the refrigerants
20 of PAG 3 to 13 cannot be explained. Thus, the correlation between the molecular
structure of PAG and the amount of THT released was examined by using HSP. Each
HSP of THT, R-290, and PAG of each No. is shown in Table 9. For HSPs of THT
and R-290, numerical values registered in the database of HSPiP Ver. 5.3, which is
computer software, were used, and the HSP of PAG of each No. was calculated by the
25 Van Krevelen method which was a calculation method mounted on HSPiP Ver. 5.3.
[0145]
- 37 -
[Table 9]
[0146] The HSP distance between R-290 and THT is a larger value than the HSP
distance between PAG and THT, and the solubility of THT in R-290 is lower than the
5 solubility of THT in PAG. Accordingly, when R-290 is dissolved in PAG, R-290
reduces the solubility of THT in the base oil, and thus, the amount of THT dissolved in
PAG is considered to be reduced.
[0147] As the HSP distance between PAG and THT is larger, the solubility of THT in
PAG is lower. As the HSP distance between PAG and R-290 is smaller, the solubility
10 of R-290 in PAG is larger. Thus, a larger amount of R-290 is dissolved in PAG, and
THT is more hardly dissolved in PAG. Accordingly, it is considered that, as the
difference between the HSP distance between PAG and THT and the HSP distance
between PAG and R-290 is a larger value, the amount of THT dissolved in PAG is
smaller, and a large amount of THT is contained in the refrigerant gas released from the
15 refrigerant circuit. The relationship between the difference between the HSP distance
between PAG and THT and the HSP distance between PAG and R-290, and the odor
intensity in evaluation test 3 is shown in Table 10.
[0148]
- 38 -
[Table 10]
[0149] As a result of the above evaluation, the following was demonstrated: when the
difference between the HSP distance between PAG and THT and the HSP distance
5 between PAG and R-290 is -2.0 or more, the amount of the sulfur-based odorant
dissolved in the base oil is sufficiently small as described above and the released
refrigerant gas has an odor intensity of 2 or more; and when the difference is -0.5 or
more, the released refrigerant gas has an odor intensity of 3 or more.
[0150] From the above results, to circulate THT with R-290 in the refrigerant circuit,
10 PAG having a difference in the HSP distance of -2.0 or more is preferably used, and
PAG having a difference in the HSP distance of -0.5 or more is more preferably used.
[0151] As a result of the present test, the solubility of THT in PAG was successfully
demonstrated in detail with the use of HSP. HSP can explain the solubility between
substances regardless of the type of molecule. Thus, it is considered that, with respect
15 to the aforementioned relationship between the difference in the HSP distance and the
odor of the refrigerant gas, the same results can be obtained not only for PAG, but also
for POE, PVE, and hydrocarbon oil. It is also considered that the same results can be
obtained not only for R-290, but also for other hydrocarbons having 1 to 4 carbon
atoms, and that the same results can be obtained not only for THT, but also for sulfur20 based odorants other than THT.
- 39 -
[0152]
By using a commercially available air conditioner for households (indoor unit
model number: MSZ-GV5620S/outdoor unit model number: MUCZ-G5620S
manufactured by Mitsubishi Electric Corporation) having a refrigerant circuit, the
5 refrigerant gas released from the refrigerant circuit was collected. In the refrigerant
circuit, 450 g of R-290 was enclosed as the main component of the refrigerant, and 290
mg (643 ppm by mass based on the mass of the refrigerant) of THT was enclosed as the
sulfur-based odorant. In the compressor, 400 g of a refrigeration oil containing PAG
(PAG No. 10 of evaluation test 3) used in evaluation test 1 as the base oil was enclosed
10 as the refrigeration oil.
[0153] The air conditioner for households was operated, and then, while stopping the
air conditioner for households, the refrigerant gas was released from the point between
the expansion valve and the evaporator and collected in a tedlar bag (1-2711-05
manufactured by AS ONE Corporation). The collected refrigerant gas was diluted to
15 1/1,000 with using high purity air (ZERO-A manufactured by Sumitomo Seika
Chemicals Company, Limited.), and then, the sensory evaluation of the odor was
carried out. The sensory evaluation was carried out by 5 examiners as in evaluation
test 3.
[0154] As the result, the odor of the refrigerant gas was an odor intensity of 3 to 4.
20 For ascertainment, the concentration of THT of the collected refrigerant gas was
analyzed by using a gas chromatography mass spectrometer (JMS-K9 manufactured by
JEOL Ltd.) as in evaluation test 1, and as the result, THT was contained in the
refrigerant gas in a concentration of 80 ppm by mass (40 ppm by volume). That is,
the THT concentration was 40 ppm by volume when the collected refrigerant gas was
25 diluted to 1/1,000 with high purity air. Accordingly, it corresponds to the odor
intensity of 4 in the odor intensity in evaluation test 2, and it was demonstrated to be
not inconsistent with the results of the sensory evaluation.
[0155] From the above results, the following was demonstrated: when PAG having a
low solubility of THT is used, the dissolution of THT in PAG is suppressed, THT is
- 40 -
allowed to circulate in the refrigerant circuit with R-290, and the refrigerant gas
released from the refrigerant circuit is recognizable by the sense of smell.
[0156] The refrigerant, the sulfur-based odorant, and the refrigeration oil are not
limited to those used in evaluation tests 1 to 5, and the concentration of the sulfur-based
5 odorant is also not limited. Also, other sulfur-based odorants can be appropriately
adjusted by calculation of the O/C ratio, HSP distance, and the others of the
refrigeration oil so that a sufficient odor can be obtained.
[0157] The embodiments and examples disclosed herein should be considered to be
exemplary in all respects and not restrictive. The scope of the present disclosure is
10 indicated by the scope of claims rather than the above description, and is intended to
include the meaning equivalent to the scope of claims and all modifications within the
scope.
REFERENCE SIGNS LIST
[0158] 1 Outdoor unit; 2 Indoor unit; 3 Compressor; 4 Condenser; 5 Outdoor blower; 6
15 Expansion valve; 7 Evaporator; 8 Indoor blower; 9 Liquid pipe; 10 Gas pipe; 11 Shell;
12 Compression mechanism; 13 Electric motor; 14 Inlet pipe; 15 Discharge pipe; 16
Accumulator; 17 Rolling piston; 18 Cylinder; 19 Cylinder chamber; 20 Upper bearing;
21 Discharge hole of upper bearing; 22 Muffler space; 23 Discharge muffler; 24
Discharge hole of discharge muffler; 25 Electric motor rotor; 26 Electric motor stator;
20 27 Oil reservoir part; 28 Driving shaft; 100 Refrigerant circuit.

We Claim :
[Claim 1] A refrigeration cycle device comprising: a refrigerant circuit
comprising a compressor, wherein
5 a refrigerant is enclosed in the refrigerant circuit,
the refrigerant contains a hydrocarbon having 1 to 4 carbon atoms and a sulfurbased odorant,
the compressor is filled with a refrigeration oil,
the refrigeration oil contains a base oil, and
10 a ratio of a number of oxygen atoms to a number of carbon atoms in a
molecular structure of the base oil is less than 0.50.
[Claim 2] A refrigeration cycle device comprising: a refrigerant circuit
comprising a compressor, wherein
15 a refrigerant is enclosed in the refrigerant circuit,
the refrigerant contains a hydrocarbon having 1 to 4 carbon atoms and a sulfurbased odorant,
the compressor is filled with a refrigeration oil,
the refrigeration oil contains a base oil, and
20 a difference between an HSP distance between the base oil and the sulfur-based
odorant and an HSP distance between the base oil and the hydrocarbon having 1 to 4
carbon atoms is -2.0 or more.
[Claim 3] The refrigeration cycle device according to claim 1 or claim 2,
25 wherein the base oil is at least one selected from the group consisting of an oxygencontaining oil and a hydrocarbon oil.
[Claim 4] The refrigeration cycle device according to any one of claims 1 to
3, wherein the base oil contains polyalkylene glycol represented by the following
- 42 -
chemical formula 1:
[Formula 1]
[Chemical formula 1]
5
wherein m and n are each a numerical value of 0 or more and represent an average of
the number of ethylene oxide groups and propylene oxide groups, and R1
and R2
are a
hydrogen atom or a hydrocarbon chain having one or more carbon atoms.
10 [Claim 5] The refrigeration cycle device according to claim 4, wherein m and
n satisfy the following formula (1) and formula (2):
m + n  100 ... (1)
n/(m+n)  0.20 ... (2).
15 [Claim 6] The refrigeration cycle device according to any one of claims 1 to
5, wherein
the sulfur-based odorant is tetrahydrothiophene, and
the refrigerant is propane.
20 [Claim 7] The refrigeration cycle device according to any one of claims 1 to
6, wherein a concentration of the sulfur-based odorant in the refrigerant is 50 ppm by
mass or more and less than 1,100 ppm by mass.