JP2009298918A - Liquid composition and refrigeration cycle apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid composition in which the constituent hydrofluoroolefin is kept chemically stable so as to be applied to an actual machine, and to provide a refrigeration cycle apparatus using the same. <P>SOLUTION: The liquid composition comprises tetrafluoropropene as a refrigerant, a lubricating oil containing carbon and hydrogen or a lubricating oil containing carbon, hydrogen, and oxygen, and a radical reaction inhibitor which inhibits a radical reaction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid composition that circulates in a refrigeration cycle and a refrigeration cycle apparatus using the same, and in particular, a liquid composition using tetrafluoropropene as a refrigerant constituting the liquid composition and a refrigeration cycle using the same. It relates to the device.

  From the viewpoint of ozone layer protection, refrigerants used in refrigeration cycle apparatuses such as air conditioners, refrigeration apparatuses, and heat pump systems include refrigerants for refrigeration air conditioners containing chlorine, such as CFC (Chloro Fluoro Carbon) -12 and HCFC (Hydro). Instead of the Chloro Fluoro carbon (22) and the like, an HFC (Hydro Fluoro Carbon) refrigerant (for example, HFC 134a, R410A, R407c, etc.) mainly composed of only carbon, hydrogen and fluorine is used. However, due to further increasing interest in global environmental issues in recent years, the use of HFC refrigerants with a large global warming potential is being avoided, and the substitution of HFC refrigerants with refrigerants with a low global warming potential is being investigated. .

  As such, hydrofluoroolefins (also called fluoroalkenes) have become promising candidates for alternative refrigerants (see, for example, Patent Document 1). This hydrofluoroolefin has a characteristic that the global warming potential is small because of its low chemical stability compared to HFC-based refrigerants. The global warming potential of R410A, one of the HFC refrigerants, is about 2000 times the global warming potential of carbon dioxide, whereas the global warming potential of hydrofluoroolefins is It is about 4 times the global warming potential. Hydrofluoroolefin also has a characteristic that the pressure is comparable to that of conventional HFC refrigerants. The global warming potential is a value indicating the degree of the greenhouse effect based on the greenhouse effect of carbon dioxide.

JP-T-2007-510039 (Example 3)

  In Example 3 of the invention according to Patent Document 1, aluminum, copper and steel are enclosed in a thick glass tube together with refrigerant and refrigerating machine oil, heated at a predetermined temperature and time, and discoloration of the refrigerating machine oil after heating, etc. Thus, it is evaluated that there is no problem with the chemical stability of the hydrofluoroolefin under such conditions.

However, when operation in an actual machine is considered using hydrofluoroolefin as a refrigerant, problems that cannot be assumed under the conditions described in Example 3 of the invention according to Patent Document 1 occur in the following points.
That is, the following problems (1) and (2) occur.
(1) In an actual machine, since there is a sliding part in the compressor, and the metal always rubs in that part, the inactive oxide present on the metal surface is removed.
(2) In actual equipment, water, air, processing oil, etc. may be mixed during the manufacturing process or installation work.

  In the third embodiment of the invention according to Patent Document 1, the condition (1) is not considered, and the chemical reaction of the active metal surface cannot be simulated. That is, the hydrofluoroolefin is assumed to be radicalized by electrons released from the active metal on the active metal surface present in the actual machine and cause various deterioration reactions. Embodiment 3 of the invention according to Patent Document 1 Therefore, the stability of the hydrofluoroolefin is evaluated without taking this point into consideration.

  In Example 3 of the invention according to Patent Document 1, since the refrigerant is added after the thick glass tube is exhausted, the condition (2) is not considered, and contaminants such as water, air, and processing oil are present. A chemical reaction in a certain state cannot be simulated. That is, hydrofluoroolefin is assumed to be deteriorated due to the addition reaction of contaminants such as water, air, and processing oil due to its chemical structure, but Example 3 of the invention according to Patent Document 1 does not consider this point. The stability of hydrofluoroolefins is evaluated. Moreover, if it is going to implement | achieve the situation like Example 3 of the invention which concerns on patent document 1 with a real machine, it will also require special attention and cost.

  The above fact is due to the chemical nature of hydrofluoroolefins. Therefore, in order to realize a refrigeration cycle apparatus using hydrofluoroolefin as a refrigerant, it is necessary to take measures against the chemical properties of the hydrofluoroolefin. In other words, unlike natural refrigerants and HFC refrigerants, hydrofluoroolefins have low chemical stability, so when used as refrigerants, refrigeration cycles must be taken without taking into account chemical changes within the refrigeration cycle. The reliability of the device will be reduced.

  Possible causes of the decrease in the reliability of the refrigeration cycle apparatus include deterioration due to chemical changes in hydrofluoroolefins and an increase in sludge (precipitate) generated due to chemical changes in hydrofluoroolefins. When the hydrofluoroolefin deteriorates, the amount of refrigerant enclosed in the refrigeration cycle decreases, and the refrigeration cycle apparatus cannot exhibit a predetermined capacity. In addition, the increase in sludge blocks the refrigerant piping and hinders the circulation of the refrigerant, and the refrigeration cycle apparatus cannot exhibit a predetermined capacity.

The following can be considered as the causes of hydrofluoroolefin degradation and sludge generation.
(1) Alcohol is produced by adding water mixed in the refrigeration cycle to the hydrofluoroolefin. This alcohol becomes acidic due to the electron withdrawing effect of fluorine. This acidic alcohol reacts with the metal constituting each device such as a compressor to produce a metal salt. This metal salt becomes sludge. Moreover, since hydrofluoroolefin will also decompose | disassemble, it will also degrade hydrofluoroolefin.

(2) A hydrofluoroolefin having a double bond is polymerized by a polymerization reaction (radical, cationic or anionic polymerization). By this polymerization, sludge having a reduced solubility in refrigerating machine oil is obtained. In addition, since the polymerized product does not have the chemical properties of hydrofluoroolefin, it also degrades the hydrofluoroolefin.
(3) Hydrofluoroolefins have double bonds and are less chemically stable than natural refrigerants and HFC refrigerants, so they easily react with radicals (free radicals) generated in the refrigeration cycle. . As a result, the hydrofluoroolefin is decomposed and deteriorated. Moreover, the decomposition product also becomes sludge.

  The present invention has been made to solve the above-mentioned problems, and provides a liquid composition that stabilizes the chemical properties of hydrofluoroolefin and can be applied to an actual machine, and a refrigeration cycle apparatus using the same. The purpose is that.

  The liquid composition according to the present invention contains tetrafluoropropene as a refrigerant, a lubricating oil containing carbon and hydrogen or a lubricating oil containing carbon, hydrogen and oxygen, and a radical reaction inhibitor that suppresses a radical reaction. It is characterized by that.

  The refrigeration cycle apparatus according to the present invention is characterized in that the liquid composition described above is circulated in a refrigeration cycle in which a compressor, a condenser, a throttling device, and an evaporator are mounted and sequentially connected by piping.

  According to the liquid composition of the present invention, since radical reaction can be suppressed, deterioration of the refrigerant composed of tetrafluoropropene and generation of sludge can be prevented. Moreover, since deterioration of tetrafluoropropene and generation of sludge can be prevented, the chemical properties of tetrafluoropropene are stabilized, and the reliability of the refrigeration cycle apparatus using this liquid composition is improved.

  Further, according to the refrigeration cycle apparatus according to the present invention, since the lubricating oil composition is circulated, the chemical properties of the refrigerant are stabilized, sludge generated in the refrigeration cycle can be reduced, and reliability is improved. Can be achieved.

Embodiments of the present invention will be described below.
Embodiment 1 FIG.
In Embodiment 1 of the present invention, the chemical properties of 2,3,3,3-tetrafluoropropene, which is one of hydrofluoroolefins (fluoroalkenes), and 2,3,3,3-tetrafluoropropene The examination when using as a refrigerant of the refrigeration cycle apparatus will be described. The chemical formula of this 2,3,3,3-tetrafluoropropene is represented by CF ₃ CF═CH ₂ . The refrigeration cycle apparatus is an apparatus using a refrigeration cycle (refrigerant circuit) that circulates refrigerant, such as an air conditioner, a refrigeration apparatus, a heat pump system, a heat pump water heater, a refrigerator, or a vending machine.

  As a result of studying the case where 2,3,3,3-tetrafluoropropene is used as a refrigerant for a refrigeration cycle device for practical use, 2,3,3,3-tetrafluoropropene constitutes a refrigeration cycle device. It has been confirmed that when there is no inactive oxide film such as the surface of each device, for example, the sliding surface of a compressor, it takes in electrons emitted from the active metal surface and generates radicals. This radical decomposes 2,3,3,3-tetrafluoropropene by further radical polymerization reaction with another 2,3,3,3-tetrafluoropropene, and converts the fluorine-based polymer compound into Form. The fluorine-based polymer compound is insolubilized (sludge) in the refrigerant and the refrigerating machine oil by increasing the molecular weight. The insolubilized polymer compound is deposited in the refrigeration cycle.

  The depositing place is often a narrow portion such as a capillary tube, an expansion valve valve seat, an expansion valve drive unit, or the like, but may also be a sliding portion in a compressor. If the fluorine-based polymer compound is deposited on the capillary, the flow of the refrigerant is hindered, and the ability of the refrigeration cycle apparatus cannot be exhibited, for example, it becomes uncooled. When the fluorine-based polymer compound is deposited on the valve seat of the expansion valve, the refrigerant flow is inhibited in the same manner as when it is deposited on the capillary tube. Further, when the fluorine-based polymer compound is deposited on the drive portion of the expansion valve, the drive portion is fixed, resulting in malfunction. In any case, the capacity of the refrigeration cycle apparatus cannot be exhibited, and for example, it becomes uncooled. If the fluorine-based polymer compound is deposited on the sliding portion of the compressor, the flow of the refrigerating machine oil is hindered, a good lubricating state is hindered, and seizure or the like is caused.

  As a result of the above studies, it has been found that radical reaction inhibitors are effective in suppressing radical reactions. The radical reaction inhibitor may be a stable radical, or may be one that generates a stable radical by reacting with a radical generated by deterioration of the refrigerant. Examples of stable radicals include phenolic compounds, diphenylpicrylhydrazyl, galvinoxyl, and ferdazil. Examples of those that generate stable radicals include p-benzoquinone, benzoquinone derivatives, and nitro compounds. In addition, as a compound that easily causes a destructive chain transfer reaction, for example, diphenylpicrylhydrazine, diphenylamine, tertiary catecholamine, and the like can be used.

Here, the first embodiment will be described in detail.
In this embodiment, as a refrigerating machine oil (lubricating oil), a commercially available hindered ester refrigerating machine oil is used which is prepared by adding 1 to 10% of a phenolic compound or a benzoquinone compound as a radical reaction inhibitor. Yes. This refrigerating machine oil and fluoroolefin compound are mixed at a weight ratio of 10: 3, and generated by operating for 72 hours at 175 ° C. in a wear tester having a sliding part made of the same material as the refrigeration cycle apparatus used The amount of sludge was weighed. In the experiment, air in the experimental apparatus is removed in advance. As the lubricating oil, esters, ethers, alkylbenzenes, mineral oils and the like can be used as the base oil.

  Under these conditions, the inactive oxide film on the surface of the sliding material that existed at the start of the test at the sliding part of the abrasion tester is removed by abrasion, and the active metal surface is exposed. become. The free electrons on the active metal surface radicalize refrigeration oil and fluoroolefin compounds. The radicalized fluoroolefin compound is polymerized with a non-radical fluoroolefin compound by a radical polymerization reaction to become a polymer compound.

  The relationship between the sludge generation amount generated by this experiment and the radical reaction inhibitor addition amount is shown in FIG. In FIG. 1, the horizontal axis represents the concentration (%) of the radical reaction inhibitor, and the vertical axis represents the normalized value of the amount of sludge generated when no radical reaction inhibitor is added. Moreover, the line (a) shown in FIG. 1 represents the case where the phenolic compound is used as the radical reaction inhibitor, and the line (a) shown in FIG. 1 represents the case where the benzoquinone compound is used as the radical reaction inhibitor. .

  As shown in FIG. 1, when a benzoquinone compound is added as a radical reaction inhibitor, a sludge reduction effect is hardly observed when the amount of the benzoquinone compound is 1% or less. Thereafter, the amount of sludge decreases according to the amount of benzoquinone compound added, and becomes a substantially constant value when the amount added is about 5% or more. It was confirmed that the sludge amount did not become zero even if the radical reaction inhibitor was effective under the conditions as in this experiment. That is, the sludge is not limited to those generated by radical polymerization. Therefore, when adding a benzoquinone compound as a radical reaction inhibitor, an addition amount of 3% or more is sufficient from the viewpoint of sludge suppression.

  In addition, when a phenolic compound is added as a radical reaction inhibitor, an effect of reducing sludge is hardly observed when the amount of the phenolic compound added is 1% or less. In the case of this phenol-based compound, the sludge amount showed a minimum value at an addition amount of 5%, and thereafter the sludge amount increased. As a result of analyzing the sludge generated when 10% of the phenolic compound was added, the main component of this sludge is a fatty acid salt which is a chemical reaction product of fatty acid generated by hydrolysis of ester oil and iron which is a sliding agent. I found out. Since the phenolic compound exhibits acidity, when the addition amount is large, hydrolysis degradation of the ester-based refrigeration oil is promoted, and the amount of sludge is increased. By the way, when a proton compound is used as a radical reaction inhibitor, it is considered that the concentration has an effective upper limit value from the viewpoint of sludge suppression.

  Therefore, when an aprotic compound is used as a radical reaction inhibitor, or when a refrigerating machine oil that does not cause hydrolysis like a polyether other than an ester is used as a lubricating oil, the amount added is from the viewpoint of sludge suppression. There is no upper limit on the concentration of. However, the radical reaction inhibitor is a solid or low-viscosity liquid, and when mixed in large quantities, it affects the viscosity characteristics of the refrigerating machine oil and causes a significant decrease in lubricity. For this reason, there is a restriction that such an additive must be used at a concentration within a range of 1% or more and 8% or less.

  Compared to the case where a phenolic compound is used as a radical reaction inhibitor, the use of an aprotic compound as a radical reaction inhibitor is limited and the concentration control becomes more strict when used. It doesn't mean you can't use it. That is, the addition amount of the radical reaction inhibitor cannot be determined only from its effect. For this reason, even when a proton radical inhibitor is used, the maximum addition amount is determined by the characteristics of the refrigerating machine oil. That is, in order for the refrigerating machine oil to maintain good lubricity, a viscosity of 5 to 70 cSt (centistokes) (that is, an ISO (International organization for standardization) viscosity grade within a range of VG = 5 to 100) is necessary. When such a viscosity is exhibited with a radical reaction inhibitor added, it can be used in a refrigeration cycle apparatus.

  From the above, when 2,3,3,3-tetrafluoropropene is used as a refrigerant, a refrigerating machine oil (a lubricating oil containing carbon and hydrogen or a lubricating oil containing carbon, hydrogen and oxygen, such as a hindered ester) System refrigerating machine oil) and radical reaction inhibitors (for example, fluoroolefin compounds) stabilize the chemical properties of 2,3,3,3-tetrafluoropropene and prevent the refrigerant function from being reduced. The ability of the cycle device can be demonstrated. In other words, when 2,3,3,3-tetrafluoropropene is used as a refrigerant, the refrigerant itself that did not need to be considered in the conventional refrigerant (natural refrigerant and HFC refrigerant) that is chemically stable. Therefore, the above-described liquid composition is prepared with sufficient consideration of this point.

Embodiment 2.
In the second embodiment of the present invention, as in the first embodiment, the chemical properties of 2,3,3,3-tetrafluoropropene and 2,3,3,3-tetrafluoropropene are used as the refrigerant of the refrigeration cycle apparatus. The examination when used as will be described. In the first embodiment, the case where the chemical properties of 2,3,3,3-tetrafluoropropene are stabilized by adding a radical reaction inhibitor has been described, but in the second embodiment, it occurs in the refrigeration cycle. The case of stabilizing the chemical properties of 2,3,3,3-tetrafluoropropene by supplementing the acid to be described will be described.

2,3,3,3-tetrafluoropropene exhibits the same chemical reactivity as aldehydes as a whole molecule due to fluorine having strong electron-withdrawing property. For example, 2,3,3,3-tetrafluoropropene is considered to react with water to produce an alcohol (see Formula [1] below). That is, 2,3,3,3-tetrafluoropropene is deteriorated. This alcohol also exhibits acidity due to fluorine having a strong electron-withdrawing property.

And the acidic alcohol which generate | occur | produced in the freezing circuit reacts with the metal which comprises the sliding material of a compressor, etc., and produces | generates a salt (metal salt). This salt has poor compatibility with the refrigerating machine oil and the refrigerant, and becomes sludge. If the generated acidic alcohol is not captured, the deterioration of the refrigerant proceeds and sludge is deposited. In order to prevent the deterioration of 2,3,3,3-tetrafluoropropene and maintain the capacity of the refrigeration cycle apparatus, it is necessary to supplement the generated acidic alcohol. In order to capture the acidic alcohol, it is preferable to add an epoxy. The reaction formula of epoxy and acidic alcohol is shown in the following formula [2].

From the above formulas [1] and [2], it can be seen that the minimum required amount of epoxy is equimolar to the amount of water. From this saturated moisture content and the amount of refrigeration oil per refrigeration cycle apparatus, the amount of water m ₁ brought into the refrigeration circuit by the refrigeration oil is determined. Similarly, the amount of moisture m ₂ brought into the refrigeration circuit by the refrigerant is determined from the saturated moisture amount of 2,3,3,3-tetrafluoropropene and the amount of refrigerant per refrigeration cycle apparatus. Therefore, m = m ₁ + m ₂ is the amount of moisture brought in. The water content m can be set to a smaller value depending on the water management status of the refrigeration oil or the refrigerant. Further, when connecting the pipe or the like can also be those by adding the amount of water m ₃ being brought into the refrigerant circuit.

この量のエポキシを冷凍機油に予め添加してもよいし、冷媒に予め添加してもよいし、配管等から冷凍サイクル装置の組み立て後に添加してもよい。 The required amount of epoxy in this case can be represented by the following formula [3], where M is the molecular weight of the epoxy.

This amount of epoxy may be added in advance to the refrigerating machine oil, may be added in advance to the refrigerant, or may be added after assembling the refrigeration cycle apparatus from a pipe or the like.

  It is preferable that the amount of the epoxy added is larger than the amount determined by the above formula [3] from the viewpoint of capturing the acid generated by the reaction between the refrigerant and the alcohol. However, since epoxy is sludged by self-polymerization, it is better to avoid excessive addition from this viewpoint. The maximum addition amount of epoxy should be determined while measuring the amount of sludge generated, but the upper limit is 10% in order to avoid the amount that affects the viscosity of the refrigerating machine oil (insulating oil) determined in the first embodiment. It is desirable to do.

  As described above, the epoxy can be converted into a polymer compound by self-polymerization and become sludge. Therefore, it is required to use an epoxy that is difficult to be polymerized by self-polymerization. In the case of having two or more epoxy groups per epoxy molecule, polymerization is likely to occur due to polymerization reaction, and those having one epoxy group per epoxy molecule are suitable as additives. Examples of such include 1,2-epoxybutane, 1,2-epoxysiloxane, 1,2-epoxy-3-phenoxypropane, 1,2-epoxyoctane, and the like.

  From the above, 2,3,3,3-tetrafluoropropene, moisture brought into the refrigerant circuit by refrigerating machine oil, moisture brought into the refrigerant circuit by the refrigerant, and moisture brought into the refrigerant circuit when connecting pipes and the like Then, the acidic alcohol generated by the above is supplemented by adding an epoxy to suppress the generation of sludge so that the ability of the refrigeration cycle apparatus can be exhibited. That is, when 2,3,3,3-tetrafluoropropene is used as a refrigerant, the conventional refrigerant (natural refrigerant and HFC-type refrigerant) that is chemically stable does not need to be considered. The above-mentioned reaction must be taken into consideration, and the liquid composition as described above is prepared with sufficient consideration of this point. Note that the contents of the second embodiment may be combined with the contents of the first embodiment.

Embodiment 3.
FIG. 2 is a schematic configuration diagram showing a schematic configuration of the refrigeration cycle apparatus 100 according to Embodiment 3 of the present invention. Based on FIG. 2, the structure and operation | movement of the refrigerating-cycle apparatus 100 are demonstrated. This refrigeration cycle apparatus 100 uses the liquid composition according to the above embodiment for a refrigeration cycle. The refrigeration cycle apparatus 100 may be an apparatus using a refrigeration cycle (refrigerant circuit), and is, for example, an air conditioner, a refrigeration apparatus, a heat pump system, a heat pump water heater, a refrigerator, or a vending machine.

  The refrigeration cycle apparatus 100 is configured by sequentially connecting a compressor 101, a condenser 102, a dryer 105, an expansion device 103, and an evaporator 104 through a refrigerant pipe 110. The dryer 106 contains an adsorbent (for example, silica gel, zeolite, mesoporous inorganic material, etc.) for adsorbing moisture brought into the refrigeration cycle. Note that FIG. 2 shows an example in which the dryer 105 is connected in series with each device by the refrigerant pipe 110, but this dryer circuit is provided with a dryer circuit in which a part of the refrigerant pipe 110 is branched. A dryer 105 may be installed in the door.

  The compressor 101 sucks the refrigerant flowing through the refrigerant pipe 110 and compresses the refrigerant to bring it into a high temperature / high pressure state. The condenser 102 performs heat exchange between the refrigerant that is conducted through the refrigerant pipe 110 and a fluid (air, water, refrigerant, etc.), and condenses and liquefies the refrigerant. The expansion device 103 decompresses and expands the refrigerant conducted through the refrigerant pipe 110. The throttling device 3 may be composed of, for example, a capillary tube or a solenoid valve. The evaporator 104 performs heat exchange between the refrigerant that is conducted through the refrigerant pipe 110 and the fluid, and evaporates and gasifies the refrigerant. The drier 106 supplements the refrigerant pipe 110 by adsorbing moisture that is conducted along with the refrigerant and the refrigerating machine oil, and prevents deterioration of the refrigerant.

Here, the operation of the refrigeration cycle apparatus 100 will be briefly described.
The refrigerant that has been compressed by the compressor 101 and has become high temperature and high pressure flows into the condenser 102. In the condenser 102, the refrigerant exchanges heat with the fluid to condense, and becomes a low-temperature / high-pressure liquid refrigerant or a gas-liquid two-phase refrigerant. The refrigerant that has flowed out of the condenser 102 flows into the dryer 105. In the dryer 105, moisture that has flowed in along with the refrigerant is supplemented. The refrigerant flowing out of the dryer 105 is decompressed by the expansion device 103 and flows into the evaporator 104 as a low-temperature / low-pressure liquid refrigerant or a gas-liquid two-phase refrigerant. In the evaporator 104, the refrigerant exchanges heat with the fluid and evaporates to become high-temperature / low-pressure refrigerant gas, which is sucked into the compressor 101 again.

  As described in the second embodiment, 2,3,3,3-tetrafluoropropene used in the refrigeration cycle apparatus 100 reacts with water to produce acidic alcohol. Therefore, by providing the dryer 105 in the refrigeration cycle, moisture that has been taken into the refrigeration cycle can be supplemented, and moisture can be removed from the refrigeration cycle. Therefore, it is possible to prevent deterioration of 2,3,3,3-tetrafluoropropene and maintain the capacity of the refrigeration cycle apparatus 100.

  As described in Embodiments 1 to 3 above, a refrigerant having the characteristics that the global warming potential is small and the pressure is similar to that of a conventional HFC refrigerant can be used in a chemically stable manner. The ability of the refrigerant can be fully exhibited. In addition, since such a refrigerant is used in the refrigeration cycle apparatus, the refrigeration cycle apparatus can also be environmentally friendly. Furthermore, the chemical stability of the refrigerant can be further improved by effectively removing the water mixed in the refrigeration cycle.

It is a graph which shows the relationship between sludge generation amount and radical reaction inhibitor addition amount. FIG. 5 is a schematic configuration diagram showing a schematic configuration of a refrigeration cycle apparatus according to Embodiment 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Refrigeration cycle apparatus, 101 Compressor, 102 Condenser, 103 Throttling apparatus, 104 Evaporator, 105 Dryer, 110 Refrigerant piping.

Claims (7)

Tetrafluoropropene as refrigerant,
A lubricating oil containing carbon and hydrogen or a lubricating oil containing carbon, hydrogen and oxygen;
A liquid composition comprising: a radical reaction inhibitor that inhibits radical reaction. The viscosity of the mixture in which the lubricating oil and the radical reaction inhibitor are mixed,
The liquid composition according to claim 1, wherein VG is in the range of 5 to 100 in ISO viscosity grade. The liquid composition according to claim 1, wherein a predetermined amount of epoxy is added. The epoxy is
One epoxy group per epoxy molecule,
Mixing water content of the lubricating oil and m _1,
The amount of moisture contained in the refrigerant is m ₂ ,
The amount of moisture mixed in the refrigerant pipe is m ₃ ,
When the molecular weight of the epoxy is M,
Addition amount of the epoxy,
_{(M 1 + m 2 + m} 3) / 18 × liquid composition according to any one of claims 1 to 3, characterized in that more than the amount represented by M. Addition amount of the epoxy,
The liquid composition according to claim 4, wherein the liquid composition is in a range of more than (m ₁ + m ₂ + m ₃ ) / 18 × M and less than 10%. The liquid composition according to any one of claims 1 to 5,
A refrigeration cycle apparatus characterized by circulating a compressor, a condenser, a throttling device, and an evaporator in a refrigeration cycle in which refrigerant pipes are sequentially connected. The refrigeration cycle apparatus according to claim 6, further comprising a dryer that supplements moisture mixed in the refrigerant pipe.

Images