FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
REFRIGERATION CYCLE APPARATUS;
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

5 TECHNICAL FIELD
[0001] The present disclosure relates to a refrigeration cycle apparatus.
BACKGROUND ART
[0002] Currently, usage of refrigerant in refrigeration cycle apparatuses is restricted by
the Law Concerning the Discharge and Control of Fluorocarbons (enforced in April,
10 2015), more specifically by global warming potential (GWP).
[0003] Because of this, refrigerants that are compliant with the GWP requirements
have been in use. As such a refrigerant, a refrigerant mixture containing a
halogenated hydrocarbon having a C-I bond such as trifluoroiodomethane which is low
in GWP and non-flammable is disclosed by PTL 1 (Japanese National Patent
15 Publication No. 2008-505989).
[0004] However, trifluoroiodomethane is an unstable compound that is easily
decomposed, so, how to deal with this unstable nature has been a problem to solve in
order to maintain long-term reliability of refrigeration cycle apparatuses and
compressors.
20 [0005] To address this problem, PTL 2 (Japanese National Patent Publication No.
2019-527286) discloses adding a diene-based compound, a phenol-based compound, a
phosphorus compound, and a nitrogen compound as a stabilizer to a compressor
lubricant oil to inhibit an increase of the concentration of acid generated due to
decomposition of a trifluoroiodomethane-containing refrigerant and to scavenge
25 radicals generated due to decomposition of a trifluoroiodomethane-containing
refrigerant, for inhibiting further decomposition of trifluoroiodomethane, deterioration
of refrigerator oil, and corrosion of metal.
[0006] However, the trifluoroiodomethane decomposition inhibiting effect of the
compound described in PTL 2 is insufficient to maintain long-term reliability of
- 3 -
refrigeration cycle apparatuses and compressors. A compound described by PTL 3
(the specification of U.S. Patent Laying-Open No. 2019/0233698) has a higher
trifluoroiodomethane decomposition inhibiting effect than that of PTL 2, but the former
has another problem of not having a vapor-phase trifluoroiodomethane decomposition
5 inhibiting effect.
CITATION LIST
PATENT LITERATURE
[0007]
PTL 1: Japanese National Patent Publication No. 2008-505989
10 PTL 2: Japanese National Patent Publication No. 2019-527286
PTL 3: U.S. Patent Laying-Open No. 2019/0233698 specification
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0008] The present disclosure has been devised in light of the above problems, and an
15 object of the present disclosure is to provide a refrigeration cycle apparatus that uses a
trifluoroiodomethane-containing refrigerant and maintains long-term reliability.
SOLUTION TO PROBLEM
[0009] A refrigeration cycle apparatus according to the present disclosure includes a
refrigeration circuit that includes a compressor, an outdoor heat exchanger, an indoor
20 heat exchanger, and an expansion valve. A refrigerant is sealed within the
refrigeration circuit, and the refrigerant includes trifluoroiodomethane. The
compressor is filled with a refrigerator oil, and the refrigerator oil contains at least one
of a first compound represented by the following chemical formula 1 and a second
compound represented by the following chemical formula 2.
25 [0010]
- 4 -
[Chemical Formula 1]
[0011]
5 [Chemical Formula 2]
[0012] In the above chemical formula 1, each of R1 to R5 is a substituent composed of
at least one of carbon atom, hydrogen atom, and oxygen atom, and at least one of R6 to
R8 is a hydrogen atom with the remainder being a substituent composed of at least one
of carbon atom, hydrogen atom, and oxygen atom. In the above chemical formula 2,
10 R1 is a substituent forming a ring structure with neighboring carbon atoms, each of R2
to R5 is a substituent composed of at least one of carbon atom, hydrogen atom, and
oxygen atom, and at least one of R6 to R7 is a hydrogen atom with the remainder being
a substituent composed of at least one of carbon atom, hydrogen atom, and oxygen
atom.
15 ADVANTAGEOUS EFFECTS OF INVENTION
[0013] The present disclosure makes it possible to provide a refrigeration cycle
apparatus that uses a trifluoroiodomethane-containing refrigerant and maintains longterm reliability.
BRIEF DESCRIPTION OF DRAWINGS
20 [0014] Fig. 1 is a schematic diagram of the configuration of a refrigeration cycle
apparatus according to Embodiment 1.
- 5 -
DESCRIPTION OF EMBODIMENTS
[0015] Hereinafter, embodiments of the present disclosure will be described with
reference to the drawing.
Embodiment 1.
5 Firstly, an overview of a refrigeration cycle apparatus according to the present
embodiment will be described briefly. Fig. 1 is a schematic diagram of the
configuration of the refrigeration cycle apparatus according to Embodiment 1. The
refrigeration cycle apparatus includes a refrigeration circuit that includes a compressor
1, a flow path switching valve 2 for switching the flow direction between cooling
10 operation and heating operation, an outdoor heat exchanger 3, an expansion valve 4,
and an indoor heat exchanger 5. For a refrigeration cycle apparatus that is not
required to switch between cooling and heating, flow path switching valve 2 is not
necessary.
[0016] For cooling, gaseous refrigerant of high temperature and high pressure
15 generated by compression by compressor 1 flows via flow path switching valve 2 (the
flow path indicated by the solid line) into outdoor heat exchanger 3, where it is
condensed. The liquid refrigerant thus condensed in outdoor heat exchanger 3 flows
via expansion valve 4 into indoor heat exchanger 5, where it is evaporated (vaporized).
Finally, the gaseous refrigerant thus evaporated in indoor heat exchanger 5 returns to
20 compressor 1 via flow path switching valve 2 (the flow path indicated by the solid
line). In this way, for cooling, refrigerant circulates in the refrigeration circuit of the
refrigeration cycle apparatus in the direction indicated by the solid-line arrows shown
in Fig. 1.
[0017] In contrast, for heating, gaseous refrigerant of high temperature and high
25 pressure generated by compression by compressor 1 flows via flow path switching
valve 2 (the flow path indicated by the dotted line) into indoor heat exchanger 5, where
it is condensed. The liquid refrigerant thus condensed in indoor heat exchanger 5
flows via expansion valve 4 into outdoor heat exchanger 3, where it is evaporated
(vaporized). The refrigerant thus evaporated in outdoor heat exchanger 3 returns to
- 6 -
compressor 1 via flow path switching valve 2 (the flow path indicated by the dotted
line). In this way, for heating, refrigerant circulates in the refrigeration circuit of the
refrigeration cycle apparatus in the direction indicated by the broken-line arrows shown
in Fig. 1.
5 [0018] The above-described elements of the configuration are the fewest possible
components required of a refrigeration cycle apparatus capable of cooling and heating
operation. The refrigeration cycle apparatus according to the present embodiment
may further include other devices such as a gas-liquid separator, a receiver, an
accumulator, and a high and low pressure heat exchanger.
10 [0019] (Refrigerant)
Next, a refrigerant to be sealed inside the refrigeration circuit according to the
present embodiment is described. The refrigerant contains trifluoroiodomethane.
[0020] Moreover, the refrigerant used in the present embodiment may contain
trifluoroiodomethane alone, or may further contain an additional component.
15 Examples of the additional component include natural refrigerants including
chlorofluorocarbon (CFC), hydrochlorofluorocarbon (HCFC), hydrofluorocarbon
(HFC), hydrofluoroolefin (HFO), and hydrocarbon. The content of the additional
component, for example, is determined so as not to impair major effects of the present
embodiment. When such an additional component is contained in addition to
20 trifluoroiodomethane, the content of trifluoroiodomethane is preferably from 1 to 70
mass% relative to the total amount of the refrigerant.
[0021] (Refrigerator Oil)
Next, a refrigerator oil to be filled for lubricating inside the compressor
according to the present embodiment is described. Examples of the refrigerator oil
25 include commonly used refrigerator oils (such as ester-based lubricant oils, ether-based
lubricant oils, fluorine-based lubricant oils, mineral-based lubricant oils, and
hydrocarbon-based lubricant oils). In this case, preferably, a refrigerator oil with
excellent compatibility with the refrigerant and excellent stability, among others, is
selected. Specific but non-restrictive examples of the refrigerator oil that can be used
- 7 -
include polyalkylene glycols, polyol esters, polyvinyl ethers, alkyl benzenes, and
mineral oils.
[0022] The refrigerator oil contains, as an additive, at least one of a first compound
represented by a chemical formula 1 and a second compound represented by a chemical
5 formula 2.
[0023] Trifluoroiodomethane decomposition reaction, and reaction in which
decomposition-generated radicals are scavenged by the compound, are as represented
by the following chemical formula 3.
[0024]
10
[Chemical Formula 3]
[0025] According to the above chemical formula 3, the basic structure of a compound
having trifluoroiodomethane decomposition inhibiting effect is either the first
compound represented by chemical formula 1 or the second compound represented by
15 chemical formula 2.
[0026]
[Chemical Formula 1]
[0027]
- 8 -
[Chemical Formula 2]
[0028] In the first compound represented by chemical formula 1, each of R1 to R5 is a
substituent composed of at least one of carbon atom, hydrogen atom, and oxygen atom,
5 preferably at least one of a hydrogen atom, a methoxy group, an ethoxy group, and an
alkyl group. R1 to R5 may be the same or different from each other. Moreover, at
least one of R6 to R8 substituents is a hydrogen atom. The remainder are each a
substituent composed of at least one of carbon atom, hydrogen atom, and oxygen atom,
preferably at least one of a hydrogen atom, a methoxy group, an ethoxy group, and an
10 alkyl group. R6 to R8 may be the same or different from each other.
[0029] Also, in chemical formula 1, R3 may be -O-R9, R9 may be a hydrocarbon group
having 1 to 10 carbon atoms, R7 may be -COO-R10, R10 may be a hydrocarbon group
having 1 to 10 carbon atoms, and each of R1 to R2, R4 to R6, and R8 may be a hydrogen
atom or a hydrocarbon group having 1 to 10 carbon atoms. The above ranges of the
15 number of carbon atoms contained by R1 to R2, R4 to R6, and R8 to R10 are given by
way of illustration, and the scope of the present disclosure is not limited to the above
ranges.
[0030] Examples of the first compound include ethylhexyl methoxycinnamate,
anethole, cinnamyl acetate, and the like, and ethylhexyl methoxycinnamate and
20 anethole are preferable.
[0031] The content of the first compound in the refrigerator oil is preferably from 5
mass% to 20 mass%, more preferably from 10 mass% to 15 mass%, further preferably
from 12 mass% to 14 mass%, relative to the total amount of the refrigerator oil.
[0032] In the second compound represented by chemical formula 2, each of R2 to R5 is
25 a substituent composed of at least one of carbon atom, hydrogen atom, and oxygen
- 9 -
atom, preferably at least one of a hydrogen atom, a methoxy group, an ethoxy group,
and an alkyl group. R2 to R5 may be the same or different from each other.
Moreover, at least one of R6 to R7 substituents is a hydrogen atom. The remainder is a
substituent composed of at least one of carbon atom, hydrogen atom, and oxygen atom,
5 preferably at least one of a hydrogen atom, a methoxy group, an ethoxy group, and an
alkyl group. R6 to R7 may be the same or different from each other. Further, R1
forms a ring structure with two neighboring carbon atoms of the benzene ring to which
R1 is bonded. The ring structure is a 5- to 8-membered carbon ring or heterocyclic
ring, preferably a 6-membered heterocyclic ring.
10 [0033] In chemical formula 2, each of R2 to R6 may be a hydrogen atom or a
hydrocarbon group having 1 to 10 carbon atoms. The above ranges of the number of
carbon atoms contained by R2 to R6 are given by way of illustration, and the scope of
the present disclosure is not limited to the above ranges.
[0034] Examples of the second compound include coumarin (see the following
15 chemical formula 4), coumarone, and the like, and coumarin is preferable. There is a
prior art involving adding fluorescent coumarin or coumarin derivative as a refrigerant
leakage detecting agent, but a compound that has a practical level of performance as a
fluorescent agent is a coumarin derivative and coumarin itself is not very fluorescent.
[0035]
20
[Chemical Formula 4]
[0036] The content of the second compound in the refrigerator oil is preferably from 1
mass% to 10 mass%, more preferably from 2 mass% to 5 mass%, further preferably
from 3 mass% to 4 mass%, relative to the total amount of the refrigerator oil.
25 [0037] The first compound and the second compound, each of which has a basic
structure enabling radical scavenging reaction shown by chemical formula 3, are highly
effective to scavenge radicals resulting from trifluoroiodomethane decomposition,
- 10 -
leading to inhibition of decomposition of non-decomposed trifluoroiodomethane,
degradation of refrigerator oil, and corrosion of metal. With this high radical
scavenging effect, the first compound and the second compound are capable of
scavenging trifluoroiodomethane radicals generated in a vapor phase (even when the
5 amount of vaporized matter is very small), that is, they have a vapor-phase
trifluoroiodomethane decomposition inhibiting effect.
[0038] In the present embodiment, as long as an object of the present disclosure is not
impaired, the refrigerator oil may contain at least one additive selected from an extreme
pressure agent, an oily agent, an antioxidant, an acid scavenger, a metal inactivator, and
10 a defoaming agent.
(Refrigeration Cycle Apparatus)
In the present embodiment, the refrigeration cycle apparatus is not particularly
limited, but may be an air conditioner for commercial use or household use, an
automobile air conditioner, a heat pump for vending machines, a cooling cabinet, a
15 refrigerator for cooling the interior of containers and cooling cabinets for maritime
transportation or the like, a chiller unit, a turbo refrigerator, or the like.
[0039] The refrigeration cycle apparatus according to the present embodiment can also
be used for a unit that is dedicated for heating cycle operation, such as floor heating
apparatuses and snow melting apparatuses. The refrigeration cycle apparatus
20 according to the present embodiment is especially useful as an air conditioner for
commercial use or household use for which downsizing of the apparatus is required.
[0040] The description herein regarding the refrigeration cycle apparatus according to
the present embodiment is directed to a configuration that has a pair of an outdoor unit
and an indoor unit connected to each other, but other configurations having a pair of
25 one outdoor unit and multiple indoor units and configurations having a pair of multiple
outdoor units and one indoor unit may also be possible.
[0041] The refrigeration cycle apparatus according to the present embodiment may also
be a room air conditioner, a packaged air conditioner, or the like capable of switching
between cooling and heating, or may also be a refrigeration cycle apparatus for low-
- 11 -
temperature apparatuses such as refrigerators.
[0042] The refrigeration cycle apparatus according to the present embodiment is
preferably a refrigeration cycle apparatus for air conditioning (an air conditioner).
[0043] Examples of the refrigeration cycle apparatus for air conditioning (air
5 conditioner) include room air conditioners, packaged air conditioners, multi air
conditioners for buildings, window-mounted air conditioners, mobile air conditioners,
and the like.
[0044] Embodiment 2.
A refrigeration cycle apparatus according to this embodiment is different from
10 the one according to Embodiment 1 in that the former contains a dissolution aid in
addition to at least one of the first compound and the second compound as an additive
for the refrigerator oil.
[0045] Addition of the dissolution aid allows for inhibiting the first compound and the
second compound from precipitating when the refrigerator oil is cooled.
15 [0046] Non-restrictive examples of the dissolution aid include polyol esters, polyvinyl
ethers, alkyl benzenes, polyalkylene glycols, and the like. The dissolution aid is
preferably a polyalkylene glycol. The other fundamental structures are the same as
those of Embodiment 1, and therefore the description will not be repeated herein.
[Examples]
20 [0047]
Samples obtained by mixing the refrigerant and the refrigerator oil according to
Embodiment 1 (Examples 1 to 7, Comparative Examples 1 to 3) were subjected to an
experiment method that was in conformity with JIS K2211:2009 (appendix B, Sealed
Tube Test) to assess their chemical stability. Table 1 below gives testing conditions,
25 and Table 2 below gives refrigerator oil mixing compositions and evaluation results.
[0048] The evaluation results include the concentration of iodide ions (I-
)
(trifluoroiodomethane decomposition product) in the refrigerator oil, the acid value and
the hue of the refrigerator oil (indicative of the degree of deterioration of the
refrigerator oil), and the presence of luster on a metal surface used in the above
- 12 -
experiment.
[0049] The results were judged as follows: the higher the trifluoroiodomethane
decomposition inhibiting effect, the smaller the iodide ion concentration and the acid
value.
5 [0050] Moreover, the higher the trifluoroiodomethane decomposition inhibiting effect
is, the slower the refrigerator oil deterioration proceeds and thereby the more colorless
and transparent the hue is. In contrast, the lower the trifluoroiodomethane
decomposition inhibiting effect is, the faster the refrigerator oil deterioration proceeds,
causing a change in hue to yellow and then to brown as well as causing a decrease in
10 the degree of transparency.
[0051] Similarly, the higher the trifluoroiodomethane decomposition inhibiting effect
is, the less the metal surface discolors, leaving the metallic luster preserved. In
contrast, the lower the trifluoroiodomethane decomposition inhibiting effect is, the
more the metal surface corrodes, causing a loss of metallic luster.
15 [0052] In light of the above, inhibition of trifluoroiodomethane decomposition is
judged based on (1) iodide ion (I-
) concentration, (2) acid value, (3) hue, and (4) luster
on the metal surface. When the values of (1) and (2) are equal or less than the upper
limits, or when the degree of transparency of (3) is high, or when metallic luster is
observed in (4), trifluoroiodomethane decomposition can be inhibited.
20 [0053] Although any of copper, iron, and aluminum may be used as the metal catalyst,
copper is the most susceptible to change, so the results in Table 2 below are given
according to judgement on the presence of luster on a copper surface.
[0054] "Vapor phase" in Table 2 below refers to when the refrigerant is in the gas state,
"Liquid phase" refers to when the refrigerant is in the liquid state; and whether luster
25 was observed on the metal surface was checked when the refrigerant in each state was
brought into contact with the metal catalyst.
[0055]
- 13 -
Table 1
Test vessel 50 cm3
Refrigerant Trifluoroiodomethane
Weight of refrigerant 7 g
Refrigerator oil Polyol ester (POE)
Weight of refrigerator oil 15 g
Metal catalyst Copper, iron, aluminum
Size of metal catalyst 1 mm (diameter) × 50 mm × 2
Temperature 140C
Time 72 hours
[0056]
Table 2
Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Comp.
Ex. 1
Comp.
Ex. 2
Comp.
Ex. 3
Refrigerator
oil mixing
composition
[mass%]
Base oil POE oil VG46 90 88 86 98 97 96 85 100 99 96
Additive
First
compound
Ethylhexyl
methoxycinnamate
10 12 14 12
Second
compound Coumarin 2 3 4 3
Stabilizer
Farnesene 1
Alkyl
naphthalene 4
Evaluation
results
Refrigerator
oil
Iodide ion conc. [ppm] < 1 < 1 < 1 < 1 < 1 < 1 < 1 200 130 10
Acid value [mg KOH/g] 0.1 0.1 0.1 < 0.1 < 0.1 < 0.1 < 0.1 > 1.0 > 0.5 0.1
Hue
Colorless and
transparent
Colorless and
transparent
Colorless and
transparent
Colorless and
transparent
Colorless and
transparent
Colorless and
transparent
Colorless and
transparent
Brown
Yellow
and
transparent
Colorless and
transparent
Metal
catalyst
Luster (Liquid phase) No Yes Yes No Yes Yes Yes No No Yes
Luster (Vapor phase) No Yes Yes No Yes Yes Yes No No No
- 14 -
[0057] As shown in Table 2 above, referring to the evaluation results regarding
refrigerator oil, Examples 1 to 7 had low iodide ion (I-
) concentrations, low acid values,
and colorless transparent hues, indicating that they had a high trifluoroiodomethane
decomposition inhibiting effect.
5 [0058] Referring to the evaluation results regarding metal catalyst, Example 1 and
Example 4 had no luster either for the vapor phase or for the liquid phase, while
Example 2, Example 3, and Examples 5 to 7 had luster for both the vapor phase and the
liquid phase. From these, Examples 2, 3, and 5 to 7 seemed to have a higher
trifluoroiodomethane decomposition inhibiting effect than Examples 1 and 4.
[0059] Comparative Example 1 had a high iodide ion (I- 10 ) concentration, a high acid
value, a brown hue, and no luster on the metal surface either for the vapor phase or for
the liquid phase, indicating that it had a low trifluoroiodomethane decomposition
inhibiting effect.
[0060] Comparative Example 2 had a high iodide ion (I-
) concentration, a high acid
15 value, a yellow transparent hue, and no luster on the metal surface either for the vapor
phase or for the liquid phase, indicating that it had a low trifluoroiodomethane
decomposition inhibiting effect.
[0061] Comparative Example 3 had a high iodide ion (I-
) concentration. Although the
other evaluation results were good, it seems to have a low trifluoroiodomethane
20 decomposition inhibiting effect.
[0062]
Samples obtained by mixing the refrigerant and the refrigerator oil (Examples 8
to 11) were subjected to an evaluation that involved checking the presence of
precipitation of the additive, namely the first compound and the second compound; as
25 shown in Table 3 below, the temperature was lowered from -20C at 5C intervals,
with each temperature being maintained for 1 hour, and when precipitation of the
additive occurred within the retention time, the temperature was recorded as "Additive
precipitation temperature".
[0063] As one of the evaluation results, the temperature at which precipitation occurred
- 15 -
during cooling of a mixture of refrigerator oil (the mixing composition is shown in
Table 4 below) and refrigerant is defined as "Additive precipitation temperature". The
better the solubility of the compound in the refrigerator oil, the lower the precipitation
temperature. Although it depends on the type of the apparatus used, in the case of a
5 refrigeration cycle apparatus, for example, the temperature inside the refrigeration
circuit can decrease to below -10C. Because of this, the temperature at which
additive precipitation occurs in refrigerator oil is preferably as low as possible.
[0064]
- 16 -
Table 3
Test vessel 96 cm3
Refrigerant Trifluoroiodomethane
Weight of refrigerant 5 g
Refrigerator oil Polyol ester (POE)
Weight of refrigerator oil 45 g
Temperature Lowered from -20C at 5C intervals
Retention time 1 Hour at each temperature
Judgement Temperature at which additive precipitation occurred
within the retention time is defined as "Additive
precipitation temperature".
[0065]
Table 4
Ex. 8 Ex. 9 Ex. 10 Ex. 11
Refrigerator
oil mixing
composition
[mass%]
Base oil POE oil VG46 80 74 96 90
Additive
First
compound
Ethylhexyl
methoxycinnamate
20 20
Second
compound
Coumarin 4 4
Dissolution
aid
Polyalkylene
glycol
6 6
Evaluation
results
Additive precipitation temperature [C] -20 -55 -20 -55
- 17 -
[0066] As shown in Table 4 above, in Example 9 and Example 11 in which
polyalkylene glycol was mixed as a dissolution aid, the first compound and the second
compound precipitated at low temperatures as compared to Example 8 and Example 10
in which polyalkylene glycol was not mixed as a dissolution aid.
5 [0067] It should be construed that the embodiments and examples disclosed herein are
given by way of illustration in all respects, not by way of limitation. It is intended that
the scope of the present disclosure is defined by claims, not by the description above,
and encompasses all modifications and variations equivalent in meaning and scope to
the claims.
10 REFERENCE SIGNS LIST
[0068] 1 compressor; 2 flow path switching valve; 3 outdoor heat exchanger; 4
expansion valve; 5 indoor heat exchanger
- 18 -
We Claim :
1. A refrigeration cycle apparatus comprising:
a refrigeration circuit, the refrigeration circuit including a compressor, an
5 outdoor heat exchanger, an indoor heat exchanger, and an expansion valve, wherein
a refrigerant is sealed within the refrigeration circuit,
the refrigerant contains trifluoroiodomethane,
the compressor is filled with a refrigerator oil,
the refrigerator oil contains at least one of a first compound represented by the
10 following chemical formula 1 and a second compound represented by the following
chemical formula 2:
[Chemical Formula 1]
15 [Chemical Formula 2]
in the chemical formula 1,
each of R1 to R5 is a substituent composed of at least one of carbon atom,
hydrogen atom, and oxygen atom, and
at least one of R6 to R8 is a hydrogen atom with the remainder being a
20 substituent composed of at least one of carbon atom, hydrogen atom, and oxygen atom,
and
- 19 -
in the chemical formula 2,
R1 is a substituent forming a ring structure with neighboring carbon atoms,
the ring structure is a 5- to 8-membered carbon ring or heterocyclic ring,
each of R2 to R5 is a substituent composed of at least one of carbon atom,
5 hydrogen atom, and oxygen atom, and
at least one of R6 to R7 is a hydrogen atom with the remainder being a
substituent composed of at least one of carbon atom, hydrogen atom, and oxygen atom.
2. The refrigeration cycle apparatus according to claim 1, wherein a content of
10 trifluoroiodomethane in the refrigerant is from 1 to 70 mass% relative to a total amount
of the refrigerant.
3. The refrigeration cycle apparatus according to claim 1 or 2, wherein, in the
chemical formula 1,
15 R7 is -COO-R10, and
R10 is a hydrocarbon group having 1 to 10 carbon atoms.
4. The refrigeration cycle apparatus according to any one of claims 1 to 3,
wherein, in the chemical formula 1,
20 R3 is -O-R9, and
R9 is a hydrocarbon group having 1 to 10 carbon atoms.
5. The refrigeration cycle apparatus according to any one of claims 1 to 4,
wherein, in the chemical formula 1,
25 each of R1 to R2, R4 to R6, and R8 is a hydrogen atom or a hydrocarbon group
having 1 to 10 carbon atoms.
6. The refrigeration cycle apparatus according to claim 1 or 2, wherein, in the
chemical formula 2,
- 20 -
each of R2 to R6 is a hydrogen atom or a hydrocarbon group having 1 to 10
carbon atoms.
7. The refrigeration cycle apparatus according to claim 1 or 2, wherein the
5 second compound is a compound represented by the following chemical formula 4.

[Chemical Formula 4]
8. The refrigeration cycle apparatus according to any one of claims 1 to 7,
10 wherein the refrigerator oil contains a dissolution aid.
9. The refrigeration cycle apparatus according to claim 8, wherein the
dissolution aid is polyalkylene glycol.
Dated this 06th 15 day of December, 2022
For MITSUBISHI ELECTRIC CORPORATION
By their Agent