Method for suppressing disproportionation reaction of working medium for refrigeration cycle, working medium for refrigeration cycle, and refrigeration cycle device

Abstract

Provided is a method for suppressing a disproportionation reaction in a working medium for a refrigeration cycle in which a working medium for a refrigeration cycle, which contains a refrigerant component that can undergo a disproportionation reaction, is circulated. Carbenes generated by a disproportionation reaction of a refrigerant component are trapped by using a reactive carbene trapping agent having higher reactivity with carbene than substances other than the carbene present in a refrigeration cycle, and the disproportionation reaction of the refrigerant component is suppressed.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for inhibiting a refrigeration cycle working medium, which is capable of effectively inhibiting or alleviating a disproportionation reaction of a fluoroolefin such as 1,1,2-trifluoroethylene, and a refrigeration cycle working medium using the same. BACKGROUND

[0002] As a refrigeration cycle working medium (refrigerant or heat medium), a fluoroolefin, particularly a hydrofluoroolefin (HFO), having an ozone layer destruction coefficient (ODP) of 0 and a global warming potential (GWP) of less than that of a conventional HFC (hydrofluorocarbon) has recently been proposed. As a representative HFO, 1,1,2-trifluoroethylene (HFO1123) or difluoroethylene (HFO1132) is known, for example. The HFO has low stability compared to the conventional HFC, and thus is less likely to remain in the atmosphere.

[0003] However, it is also known that the HFO is susceptible to a self-polymerization reaction called a disproportionation reaction (hereinafter referred to as a disproportionation reaction) due to its low stability. It is also known that the disproportionation reaction is induced by heat generation during use of the refrigeration cycle working medium, and that the disproportionation reaction occurs in a chain reaction manner because the disproportionation reaction is accompanied by a large amount of heat generation. As a result, a large amount of smoke is generated, which can cause a decrease in reliability of the refrigeration cycle system or a compressor or the like constituting the system.

[0004] Therefore, for example, in Patent Literature 1, when 1,1,2-trifluoroethylene is used as a refrigerant component of a refrigeration cycle working medium, a radical scavenger is proposed as a component (disproportionation inhibitor) for inhibiting the disproportionation reaction of the 1,1,2-trifluoroethylene. In Patent Literature 1, as a specific radical scavenger, a compound having a C-X (X is Cl, Br, or I) bond and a C-X bond energy lower than that of other bonds in the molecule is listed as [1], CX4 (X is Cl, Br, or I, and the four Xs are the same) is listed as [2], and Rf-X (Rf is a perfluoroalkyl group having 1 to 6 carbon atoms, and X is Cl, Br, or I) is listed as [3].

[0005] PRIOR ART DOCUMENTS PATENT LITERATURE Patent Literature 1: Japanese Patent No. 6455506 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION However, according to further studies by the inventor of the present application, it was confirmed that when the radical scavenger described in Patent Literature 1 is used, the disproportionation reaction of the fluoroolefin such as 1,1,2-trifluoroethylene can not be effectively inhibited or alleviated.

[0007] The present application has been achieved in order to solve such a technical problem, and has an object to provide a novel method capable of well inhibiting or mitigating the disproportionation reaction of a fluoroolefin in a working medium for a refrigeration cycle containing the fluoroolefin as a refrigerant component.

[0008] Technical solution for solving the technical problem In order to solve the above-described technical problem, the inventors of the present application have conducted intensive studies, and as a result, have independently found that, among substances generated in association with the disproportionation reaction of a fluoroolefin, a carbene which has not been focused on before sometimes participates in the chain progression of the disproportionation reaction, thereby completing the present application.

[0009] In order to solve the above-described technical problem, the present application relates to a method for inhibiting the disproportionation reaction of a working medium for a refrigeration cycle, which is configured to: in a refrigeration cycle in which a working medium for a refrigeration cycle containing a refrigerant component which undergoes a disproportionation reaction is circulated, capture a carbene generated by the disproportionation reaction of the refrigerant component, using a carbene trapping agent having a reactivity higher than that of a substance other than the carbene present in the refrigeration cycle, and inhibit the disproportionation reaction of the refrigerant component.

[0010] By the above-described configuration, the carbene which is confirmed to participate in the chain progression of the disproportionation reaction of the refrigerant component is captured using the carbene trapping agent. Thereby, the increase of the carbene in the refrigeration cycle can be well inhibited, and thus the disproportionation reaction of the refrigerant component can be inhibited or mitigated.

[0011] It is particularly confirmed that, in the disproportionation reaction of the refrigerant component, the carbene is slowly generated and remains in an induction stage before the autocatalysis of the refrigerant component is about to proceed in a chain, and the chain reaction occurs when a prescribed upper limit value which is a critical condition is exceeded. By the above-described configuration, since the reactivity of the carbene trapping agent with the carbene is higher than that with a substance other than the carbene present in the refrigeration cycle (for example, a free radical), the carbene remaining in the induction stage can be well captured. As a result thereof, the concentration of the carbene can be effectively avoided or inhibited from exceeding the critical condition, and thus the chain progression of the disproportionation reaction of the refrigerant component can be inhibited or mitigated.

[0012] In addition, the present application also includes a method for trapping a carbene present in a refrigeration cycle, which is configured to: in a refrigeration cycle containing a refrigeration cycle composition, the refrigeration cycle composition containing a carbene trapping agent having a reactivity higher than that of a substance other than the carbene present in the refrigeration cycle, trap the carbene present in the refrigeration cycle by allowing the carbene trapping agent to react with the carbene present in the refrigeration cycle.

[0013] Further, the present application also includes a composition for a refrigeration cycle, which is configured to include a carbene trapping agent having higher reactivity with a carbene than with a substance other than the carbene. The present application also includes a refrigeration cycle device including the composition for a refrigeration cycle.

[0014] The above objects, other objects, features and advantages of the present application will be made clearer by referring to the accompanying drawings and the following preferred embodiments.

[0015] Effects of Invention With the present application, the following effects can be obtained: By the above configuration, a novel method for inhibiting or mitigating the disproportionation reaction of a fluoroolefin in a working medium for a refrigeration cycle including the fluoroolefin as a refrigerant component can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a schematic diagram showing an example of a state in which the carbene trapping agent reacts with the carbene to generate a singlet ground state molecule in the present application.

[0017] Figure 2 is a schematic diagram showing an example of a process in which the carbene trapping agent functions as a catalyst to generate a singlet ground state molecule from a carbene in the present application.

[0018] Figure 3 is a schematic diagram showing a main part configuration of an inside of a compressor possessed by a refrigeration cycle according to an embodiment of the present application.

[0019] Figure 4 in Figure 4 A and Figure 4 B is a schematic block diagram showing an example of a refrigeration cycle system to which a refrigeration cycle according to an embodiment of the present application is applied. DETAILED DESCRIPTION

[0020] The method for inhibiting the disproportionation reaction of the working medium for a refrigeration cycle according to the present application is configured to: in a refrigeration cycle in which a working medium for a refrigeration cycle including a refrigerant component that undergoes a disproportionation reaction is circulated, trap the carbene generated due to the disproportionation reaction of the refrigerant component using a carbene trapping agent having higher reactivity with the carbene than with a substance other than the carbene present in the refrigeration cycle, and inhibit the disproportionation reaction of the refrigerant component.

[0021] By the above configuration, the carbene that definitely participates in the chain progress of the disproportionation reaction of the refrigerant component is trapped using the carbene trapping agent. Thus, the increase of the carbene in the refrigeration cycle can be well inhibited, and thus the disproportionation reaction of the refrigerant component can be inhibited or mitigated.

[0022] It is particularly clear that in the disproportionation reaction of the refrigerant component, in the induction stage before the self-decomposition of the refrigerant component is about to proceed in a chain, carbenes are slowly generated and remain, and when the prescribed upper limit value as a critical condition is exceeded, a chain reaction occurs. With the above configuration, since the reactivity of the carbene trapping agent with carbenes is higher than the reactivity with substances other than carbenes (e.g., radicals) present in the refrigeration cycle, the carbenes remaining in the induction stage can be well trapped. As a result, the concentration of carbenes can be effectively prevented or inhibited from exceeding the critical condition, and thus the progress of the chain of the disproportionation reaction of the refrigerant component can be inhibited or mitigated.

[0023] In the method of inhibiting the disproportionation reaction of the working medium for a refrigeration cycle according to the above configuration, the carbene can include at least one selected from CF2, CHF, and CF2 n F2 (where n is any integer of 2, 3, 4).

[0024] In the method of inhibiting the disproportionation reaction of the working medium for a refrigeration cycle according to the above configuration, when trapping the carbene, the step of including the reaction of the carbene trapping agent with the carbene to convert the carbene into a singlet ground state molecule having no unpaired electron can be included.

[0025] In the method of inhibiting the disproportionation reaction of the working medium for a refrigeration cycle according to the above configuration, when trapping the carbene, the step of including the reaction of the carbene trapping agent with the carbene to convert the carbene into a singlet ground state molecule having no unpaired electron can be included.

[0026] In the method of inhibiting the disproportionation reaction of the working medium for a refrigeration cycle according to the above configuration, the inhibition of the disproportionation reaction of the refrigerant component can be the inhibition of the increase of the carbene in the refrigeration cycle, and when inhibiting the increase of the carbene, the step of making the concentration of the carbene lower than the upper limit value of the concentration of the carbene set in advance or making the concentration of the carbene substantially 0 can be included.

[0027] In the method of inhibiting the disproportionation reaction of the working medium for a refrigeration cycle according to the above configuration, the refrigeration cycle can have a compressor, and the compressor can include a discharge region in which discharge can occur and a sliding region having a plurality of sliding members to slide in a state of contacting each other's sliding surfaces, and the inhibition of the disproportionation reaction of the refrigerant component can be the inhibition of the increase of the carbene present in at least one of the discharge region and the sliding region.

[0028] Further, in the method for inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to the above configuration, the mole fraction of the carbene in at least one of the discharge region and the sliding region can be 0.35 or less.

[0029] Further, in the method for inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to the above configuration, the temperature of at least one of the discharge region and the sliding region can be controlled to 700 K or less to inhibit the increase of the carbene.

[0030] Further, in the method for inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to the above configuration, the pressure of at least one of the discharge region and the sliding region can be controlled from a high-temperature high-pressure state to 2 MPa or less to inhibit the increase of the carbene.

[0031] Further, the present application also includes a method for capturing a carbene present in a refrigeration cycle, which is configured to capture a carbene present in a refrigeration cycle containing a composition for a refrigeration cycle, the composition for a refrigeration cycle containing a carbene trapping agent having a reactivity higher than that of a substance other than the carbene present in the refrigeration cycle, by allowing the carbene trapping agent to react with the carbene present in the refrigeration cycle.

[0032] Further, the present application also includes a composition for a refrigeration cycle, which is configured to contain a carbene trapping agent having a reactivity higher than that of a substance other than the carbene.

[0033] In the composition for a refrigeration cycle according to the above configuration, the carbene trapping agent can be a singlet ground state molecule containing π electrons or a lone pair of electrons.

[0034] Further, in the composition for a refrigeration cycle according to the above configuration, the composition can further contain an ethylene-based fluoroolefin.

[0035] Further, in the composition for a refrigeration cycle according to the above configuration, the ethylene-based fluoroolefin can be 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene, or monofluoroethylene.

[0036] Further, in the composition for a refrigeration cycle according to the above configuration, the composition can further contain difluoromethane.

[0037] Further, in the composition for a refrigeration cycle according to the above configuration, the composition for a refrigeration cycle according to claim 11 can further contain a saturated hydrocarbon.

[0038] Furthermore, in the above-described composition for refrigeration cycles, the saturated hydrocarbon may contain n-propane.

[0039] Furthermore, the composition for refrigeration cycling described above may be configured to contain a haloalkane having 1 or 2 carbon atoms.

[0040] The present invention also includes a refrigeration cycle apparatus comprising a refrigeration cycle composition having the above-described structure.

[0041] The following describes in detail the representative embodiments and representative applications of the method for suppressing the disproportionation reaction of the working medium for refrigeration cycles involved in this invention.

[0042] [Fluoroolefins] The object of the method for suppressing disproportionation reaction involved in this invention, namely the working medium for refrigeration cycle involved in this invention, is at least a fluorinated olefin (fluorinated olefin, fluorinated alkene) that will undergo disproportionation reaction as a refrigerant component.

[0043] Examples of fluorinated alkenes that undergo disproportionation reactions include, but are not specifically limited to, ethylene-based fluorinated alkenes such as 1,1,2-trifluoroethylene (CF2=CHF, HFO1123), trans-1,2-difluoroethylene (CHF=CHF(E), HFO1132(E)), cis-1,2-difluoroethylene (CHF=CHF(Z), HFO1132(Z)), 1,1-difluoroethylene (CF2=CH2, HFO1132a), tetrafluoroethylene (CF2=CF2, FO1114), and monofluoroethylene (CFH=CH2). These fluorinated alkenes can be used as a refrigerant component in isolation, either individually or in combination of two or more.

[0044] These fluoroolefins have the following chemical structures: an ethylene structure as the backbone, i.e., carbon-carbon double bonds, where at least one of the two hydrogen atoms bonded to one carbon atom is replaced by a fluorine atom, or at least one of the four hydrogen atoms bonded to two carbon atoms is replaced by a fluorine atom. Additionally, in fluoroolefins, some hydrogen atoms may be replaced by other atoms or other substituents.

[0045] For example, 1,1,2-trifluoroethylene has the following structure: both hydrogen atoms bonded to one carbon atom (the carbon atom at position 1) in the ethylene structure are replaced by fluorine atoms, and one of the two hydrogen atoms bonded to the other carbon atom (the carbon atom at position 2) is replaced by a fluorine atom.

[0046] Alternatively, trans-1,2-difluoroethylene has the following structure: one of the two hydrogen atoms bonded to the carbon atom at position 1 of the ethylene structure is replaced by a fluorine atom, and in the two hydrogen atoms bonded to the carbon atom at position 2, from the perspective of the fluorine atom bonded to the carbon atom at position 1, the hydrogen atom separated only by the opposite position of the double bond, rather than the adjacent position, is replaced by a fluorine atom.

[0047] As mentioned above, such fluorinated alkenes contain an ethylene backbone, i.e., a carbon-carbon double bond, which is easily decomposed. Specifically, atmospheric ozone generates hydroxyl radicals (OH radicals) through photochemical reactions, and these hydroxyl radicals can undergo addition reactions with the double bonds, thus fluorinated alkenes readily decompose. Therefore, fluorinated alkenes have a small impact on ozone layer depletion and global warming.

[0048] Here, it is also known that fluoroolefins, due to their excellent decomposition properties, can initiate vigorous disproportionation reactions. As a representative example of fluoroolefins, 1,1,2-trifluoroethylene is cited as an example for explanation. In this disproportionation reaction, a self-decomposition reaction occurs, in which the 1,1,2-trifluoroethylene molecule decomposes. Following this self-decomposition reaction, polymerization reactions occur where the active free radicals or carbenes generated from the decomposition (hereinafter collectively referred to as active species) react with the surrounding 1,1,2-trifluoroethylene, or a soot formation reaction occurs where carbon fragments generated from dissociation polymerize to form soot. When active species are generated under high temperature and high pressure conditions due to exothermic reactions, these active species react with 1,1,2-trifluoroethylene in a polymerization reaction or a soot formation reaction, or both reactions are repeated, thus resulting in a disproportionation reaction. This disproportionation reaction is accompanied by exothermic reactions; therefore, active free radicals are generated due to this exothermic reaction, and these active free radicals further initiate disproportionation reactions. Thus, the generation of active free radicals and the occurrence of disproportionation reactions proceed in a chain reaction, and spontaneous self-decomposition reactions are transferred to other 1,1,2-trifluoroolefins, thereby causing the disproportionation reaction to proceed violently.

[0049] The inventors previously conducted in-depth research and clarified that the active free radicals that initiate the disproportionation reaction of 1,1,2-trifluoroethylene are mainly fluorine free radicals (F free radicals) and trifluoromethyl free radicals (CF3 free radicals).

[0050] Furthermore, the inventors of this invention independently discovered that by including a substance capable of efficiently capturing these active free radicals in the working medium used for freezing cycles as a "disproportionation inhibitor," severe disproportionation reactions can be suppressed or alleviated. Additionally, as disclosed in Patent Document 1 above, it is also known that the use of free radical scavengers can achieve the suppression or mitigation of disproportionation reactions.

[0051] However, further in-depth research by the inventors of this invention has clarified that when using free radical scavengers, it may not be possible to effectively inhibit or alleviate the disproportionation reaction of fluorinated alkenes such as 1,1,2-trifluoroethylene.

[0052] [Carbene trapping agent] The disproportionation reaction of fluoroolefins proceeds rapidly and can be divided into an initial stage, an induction stage, and a chain reaction stage. In the initial stage, induced by factors such as discharge within a compressor, the initial self-decomposition of the fluoroolefin occurs. At this time, reactive free radicals are readily generated. The induction stage occurs immediately after the initial stage and just before the chain reaction stage, i.e., just before the explosive self-decomposition of the fluoroolefin. In this stage, carbenes, such as CF2, are slowly generated and retained. During this induction stage, it can be considered that the self-decomposition reaction of the fluoroolefin proceeds rapidly when the carbene concentration exceeds an upper limit.

[0053] Therefore, even if the active free radicals are captured and eliminated by free radical scavengers in the initial stage, the carbene will remain slowly in the induction stage. If its concentration exceeds the specified value (critical condition), it will move to the chain process stage, and the self-decomposition of fluoroolefins will proceed explosively.

[0054] Here, in Patent Document 1, without fully clarifying the self-decomposition reaction pathway of 1,1,2-fluoroolefin (HFO1123), based on research using computer chemistry, it is predicted that carbene species will be generated in the initial stage of the reaction due to the breaking of carbon-carbon double bonds, and free radical species will be generated along with the movement of halogen atoms (paragraph

[0022] of Patent Document 1).

[0055] Based on this prediction, Patent Document 1 suggests that by capturing free radical species and carbene species that are assumed to be generated in the early stage of the self-decomposition process at the initial stage of the reaction, a chain reaction of self-decomposition (disproportionation reaction) can be prevented (paragraph

[0027] of Patent Document 1). As a result, Patent Document 1 proposes free radical scavengers as follows: [1] compounds having C-X (X is Cl, Br or I) bonds and C-X bond energy is lower than other bond energies in the molecule; [2] CX4 (X is Cl, Br or I, and the four Xs are the same); [3] Rf-X (Rf is a perfluoroalkyl group with 1 to 6 carbon atoms, and X is Cl, Br or I).

[0056] However, as the name suggests, these "free radical scavengers" are designed to scavenge reactive free radicals, not carbenes. That is, these free radical scavengers [1] to [3] are molecules with fractured sites possessing free radical properties, readily reacting with free radicals, but exhibiting low reactivity with carbenes. In other words, while Patent Document 1 suggests the generation of carbenes accompanying the self-decomposition of fluoroolefins, the primary cause of the chain reaction of self-decomposition is determined to be reactive free radicals.

[0057] In this regard, according to the inventors' research based on the present invention, as described above, it has been clarified that in the initial stage of the self-decomposition of fluoroolefins, the generation of active free radicals is dominant, and carbene is slowly generated in the subsequent induction stage. Therefore, it has been independently discovered in the present invention that, in order to suppress the chain process of the self-decomposition of fluoroolefins, it is very important to keep the carbene retained in the induction stage below a specified value.

[0058] Therefore, in this invention, a carbene scavenger is added to the working medium for the refrigeration cycle, exhibiting a higher reactivity with carbene than with substances other than carbene present in the refrigeration cycle. Consequently, the carbene generated during the induction phase is captured by the carbene scavenger. As a result, the increase of carbene within the refrigeration cycle can be suppressed, effectively inhibiting or mitigating the disproportionation reaction of fluoroolefins.

[0059] The method for suppressing the disproportionation reaction of the working medium for refrigeration cycles involved in this invention can be, for example, as follows: Figure 1 As shown in the illustration. Figure 1 In the diagram, compressor 16 is schematically represented by a large circle. Within compressor 16, the location of discharge, which is one of the inducing factors of disproportionation reaction (self-decomposition reaction of fluoroolefins), is schematically represented as discharge region 201 located in the center of the schematic compressor 16.

[0060] Assuming the temperature of discharge region 201 reaches approximately 3,000 K to 10,000 K, effluent is generated around discharge region 201. Figure 1 Region 201a, represented by grid lines, represents temperatures ranging from approximately 400 K to 1,000 K. Products generated from the self-decomposition of fluoroolefins are retained in region 201a. These products are not the final products of the self-decomposition reaction but are positioned as "intermediates." For ease of explanation, this region 201a is referred to here as the reaction intermediate retention region 201a. Carbene 31 is slowly retained in this reaction intermediate retention region 201a.

[0061] In this invention, the working medium for the refrigeration cycle contains a carbene scavenger 32. The carbene scavenger 32 is highly reactive with carbene 31, but relatively less reactive with other substances present in the refrigeration cycle, including the reaction intermediate retention region 201a. Therefore, the carbene scavenger 32 scavenges carbene 31, converting it into a singlet ground-state molecule 33 without unpaired electrons. As a result, the chain reaction of self-decomposition of fluoroolefins can be suppressed or avoided, and the disproportionation reaction can be effectively suppressed or mitigated.

[0062] The carbene scavenger involved in this invention can be any substance whose reactivity with carbene is higher than its reactivity with substances other than carbene present in the freezing cycle; typically, it can be a singlet ground-state molecule containing π electrons or unshared electron pairs. Such a carbene scavenger can react with carbene, converting the carbene into a singlet ground-state molecule without unpaired electrons.

[0063] A singlet ground-state molecule without unpaired electrons is a stable molecule with sufficiently low reactivity, having an energy level difference of more than 200 kJ / mol from the first excited triplet state. By converting carbene into such a stable molecule, the chain reaction of self-decomposition of fluoroalkenes can be substantially avoided, effectively suppressing or mitigating disproportionation reactions.

[0064] In this invention, the singlet ground-state molecules containing π electrons or non-shared electron pairs listed as representative examples of carbene scavengers differ from, for example, the "free radical scavengers" disclosed in Patent Document 1, and may not have free radical breakage sites. For example, dissociable σ bonds with bond energies of 300 kJ / mol or less can be listed as bonds that can be free radical breakage sites. Therefore, the carbene scavenger in this invention can be a molecule that does not have dissociable σ bonds with bond energies of 300 kJ / mol or less.

[0065] In this invention, the specific type of carbene targeted as a carbene scavenger is not particularly limited, as long as it is a carbene generated through the self-decomposition of fluoroolefins. Representative examples include those selected from CF2, CHF, and C. n At least one of F2 (where n is any integer of 2, 3, or 4). Among these, CF2 can be listed as a representative carbene.

[0066] The carbene scavenger involved in this invention is a substance that is highly reactive with, for example, CF2, and more specifically, the following [1] or [2] substances can be listed.

[0067] [1] Compounds with the lowest empty orbital (LUMO) that is close in energy to the highest occupied orbital (HOMO: ionization energy 11.4 eV) of CF2, i.e., compounds with high electron affinity and high Lewis basicity.

[0068] [2] Molecules with HOMO (electron affinity 0.2 electron volts) that are close in energy to CF2’s LUMO (electron affinity 0.2 electron volts), i.e. molecules with low ionization energy.

[0069] Examples of such carbene scavengers include ketones with non-shared electron pairs. Representative ketones include, for example, 1,1,1-trifluoroacetone (1,1,1-trifluoro-2-acetone, CF3-CO-CH3), 1,1,1,3,3-pentafluoroacetone (1,1,1,3,3-pentafluoro-2-acetone, CF3-CO-CHF2), 1,1,1,3-tetrafluoroacetone (1,1,1,3-tetrafluoro-2-acetone, CF3-CO-CH2F), acetone (2-acetone, CH3-CO-CH3), etc., but there are no particular limitations.

[0070] Alternatively, the carbene scavenger involved in this invention may not be a substance that reacts with carbenes to capture them, but rather a substance that acts as a catalyst. That is, in this invention, the carbene scavenger can also act as a catalyst, being a substance that converts two or more carbenes into a singlet ground-state molecule without unpaired electrons.

[0071] exist Figure 1 The schematic diagram illustrating the method for inhibiting the disproportionation reaction schematically represents the process by which a carbene scavenger reacts with a carbene, thereby generating a singlet ground-state molecule from the carbene. In contrast, in... Figure 2 The schematic diagram of the method for inhibiting the disproportionation reaction illustrates the process by which a carbene scavenger acts as a catalyst to generate a singlet ground-state molecule from a carbene.

[0072] like Figure 2 As shown, when carbene 31 is generated due to the self-decomposition of fluorinated olefins, the carbene scavenger 34, acting as a "catalyst," adsorbs (or binds, etc.) carbene 31 to form "metastable state 1." Then, the catalyst (carbene scavenger 34) of metastable state 1 further adsorbs (or binds, etc.) carbene 31 to form "metastable state 2." In metastable state 2, the two carbene 31 remain in a state where they are each adsorbed (or bound, etc.) by the catalyst (carbene scavenger 34). Subsequently, through the catalytic action of the carbene scavenger 34, the two carbene 31 react in a manner that binds to each other, thus converting these carbene 31 into a singlet ground-state molecule 33 without unpaired electrons.

[0073] Furthermore, through the inventors' dedicated research according to the present invention, it has been clarified that carbene is easily generated not only in the aforementioned discharge region 201 within the compressor, but also in regions where sliding portions exist. Here, "sliding portion" refers to a location where multiple sliding components slide in contact with each other's sliding surfaces.

[0074] If we evaluate the ease of carbene formation on a time axis, as mentioned above, carbene is easily formed immediately after the discharge that triggers self-decomposition, or after the free radicals generated by self-decomposition disappear, or just before a chain reaction of self-decomposition is about to occur. Furthermore, if we evaluate the ease of carbene formation within the compressor's internal area, it is formed in the region where the discharge that triggers self-decomposition can occur, i.e., the discharge region (refer to...). Figure 1 Of course, carbene is easily generated. It is also known that carbene is easily generated in and around parts of the compressor, such as sliding parts, where high temperature and high pressure occur.

[0075] In this invention, the region containing the sliding portion within the compressor is designated as a "sliding region." In the method for suppressing the disproportionation reaction according to this invention, it is sufficient that at least one of these discharge regions and sliding regions, or both the discharge regions and sliding regions, can suppress the increase of carbene.

[0076] For a representative example of the discharge region and sliding region in a compressor, refer to... Figure 3 Please provide a detailed explanation. Figure 3 An example of a rotary (or scroll) compressor is shown. Additionally, in Figure 3 In order to facilitate the explanation of the discharge region and the sliding region, only the main components related to these regions are shown in the figure. The main components of a representative compressor are not all shown.

[0077] Furthermore, the freezing cycle to which the method for suppressing disproportionation reactions according to the present invention is applicable is not limited to... Figure 3 The diagram shows the configuration of a rotary (or scroll) compressor. The refrigeration cycle to which this invention is applicable can have a piston compressor or other known compressor types.

[0078] Similarly, in this invention, the constituent elements of the compressor are not limited to, regardless of whether it is rotary (or scroll) type. Figure 3 The main components are schematically represented in the diagram. In various known compressor types, the parts where discharge can occur and their surroundings can be referred to as "discharge areas," and the parts that will become high-temperature and high-pressure areas and their surroundings can be referred to as "sliding areas" (or high-temperature and high-pressure areas).

[0079] Figure 3 The compressor 16 shown in this embodiment has an electric motor section 162 and a compression mechanism section 163 within a sealed container 161. The electric motor section 162 and the compression mechanism section 163 are connected by a rotating shaft 166. The electric motor section 162 consists of at least a stator 164 fixed to the inner surface of the sealed container 161 and a rotor 165 rotating within the stator 164.

[0080] An airtight power terminal 173 is sealed and welded within a sealed container 161. The airtight power terminal 173 is electrically connected to an external power source and is also electrically connected to the stator 164 of the motor unit 162 within the sealed container 161 via a wiring 174. Thus, power can be supplied to the motor unit 162 from an external power source.

[0081] In compressor 16, the compression mechanism section 163 includes a first compression mechanism section 163A and a second compression mechanism section 163B. The first compression mechanism section 163A has a first piston 169A disposed in a first cylinder and vanes separating the first cylinder. By revolving within the first cylinder, the first piston 169A draws in low-pressure refrigerant gas (working medium for the refrigeration cycle) and compresses it. By arranging the first piston 169A in a manner that allows it to revolve within the first cylinder, a first compression chamber 172A is formed.

[0082] The second compression mechanism 163B, like the first compression mechanism 163A, has a second piston 169B disposed within the second cylinder and vanes separating the second cylinder. The second piston 169B revolves within the second cylinder, drawing in low-pressure refrigerant gas (working medium for the refrigeration cycle) and compressing it. By arranging the second piston 169B within the second cylinder in a manner capable of revolving, a second compression chamber 172B is formed.

[0083] Rotating shaft 166 fixes rotor 165 and is rotatably supported by main bearing 167 and secondary bearing 168. In addition, first piston 169A and second piston 169B are fixed on rotating shaft 166 with a phase difference of 180 degrees from each other.

[0084] The bottom of the sealed container 161 stores lubricating oil, which lubricates the sliding part formed by the rotating shaft 166 and the main bearing 167 or the sliding part formed by the rotating shaft 166 and the secondary bearing 168 through the oil supply path formed on the rotating shaft 166.

[0085] A first suction pipe 171A and a second suction pipe 171B are connected to the side of a sealed container 161. The first suction pipe 171A is connected to a first compression chamber 172A, and the second suction pipe 171B is connected to a second compression chamber 172B. A liquid receiver 170 is provided upstream of the first suction pipe 171A and the second suction pipe 171B. The liquid receiver 170 separates the refrigerant, which is in a gas-liquid mixed state and returns from the refrigeration cycle, into liquid refrigerant and gaseous refrigerant. The gaseous refrigerant flows in the first suction pipe 171A and the second suction pipe 171B.

[0086] Rotation of the rotating shaft 166 causes the first piston 169A and the second piston 169B to revolve within the first compression chamber 172A and the second compression chamber 172B. Through this revolve motion, the gaseous refrigerant drawn into the first compression chamber 172A and the second compression chamber 172B from the first suction pipe 171A and the second suction pipe 171B is compressed within the chambers and then discharged into the sealed container 161. During its ascent through the motor section 162, lubricating oil is separated and discharged from the discharge pipe outside the sealed container 161.

[0087] exist Figure 3 In the configuration example shown, the discharge regions 201A and 201B within the compressor 16 are the areas enclosed by dashed frames, and the sliding region is the area enclosed by dotted frames. Specifically, discharge region 201A is the coil portion of the stator 164 constituting the motor section 162 and its surrounding area, and discharge region 201B is the hermetically sealed power terminal 173 and its surrounding area.

[0088] On the other hand, Figure 3 In the configuration example shown, the sliding parts (the parts in which multiple sliding components are combined and slide in contact with each other on their sliding surfaces) that are prone to high temperature and high pressure within the compressor 16 can be listed as the first piston 169A or the second piston 169B and the blades, the main bearing 167 and the rotating shaft 166, the rotor 165 and the main bearing 167, etc.

[0089] Therefore, in Figure 3 For example, the sliding region 202A is defined as the area between the first piston 169A and the blade and its surroundings, and the area between the second piston 169B and the blade and its surroundings. Similarly, the sliding region 202B (the area enclosed by the dotted line frame) is defined as the area between the main bearing 167 and the rotating shaft 166 and its surroundings, and the sliding region 202C (the area enclosed by the dotted line frame) is defined as the area between the rotor 165 and the main bearing 167 and its surroundings.

[0090] In this invention, it is sufficient that the increase of carbene can be suppressed by using a carbene scavenger within the refrigeration cycle including the compressor 16. Furthermore, it is sufficient that the increase of carbene can be suppressed by using a carbene scavenger within the refrigeration cycle, within the compressor 16, in at least any one of the discharge regions 201A, 201B, and sliding regions 202A to 202C.

[0091] In particular, if the increase of carbene in discharge regions 201A and 201B can be suppressed by using a carbene scavenger, the allowable discharge energy, i.e., the discharge energy of the non-chain self-decomposition of fluoroolefins, can be increased. Therefore, the disproportionation reaction can be better suppressed or mitigated.

[0092] Among them, Figure 3 In the example shown, two discharge regions and three sliding regions are illustrated within the compressor 16, but the number of discharge regions and sliding regions in this invention is not limited to this. Figure 4 The example shown illustrates this. The compressor 16 may contain multiple discharge regions or only one sliding region. In this invention, "at least one of the discharge regions and sliding regions" refers to at least one of the discharge regions and sliding regions present in the compressor 16. Furthermore, "at least one of the discharge regions and sliding regions" also includes cases with only one or more discharge regions, cases with one or more sliding regions, and cases with all discharge regions and sliding regions.

[0093] In the method for suppressing the disproportionation reaction of the working medium for refrigeration cycles according to the present invention, the aforementioned carbene scavenger can suppress the increase of carbene in the refrigeration cycle. As a result, the disproportionation reaction of fluoroolefins contained in the working medium for refrigeration cycles can be suppressed or alleviated. Therefore, in the present invention, in order to suppress the increase of carbene, an upper limit value of the carbene concentration is preset in the refrigeration cycle. When the carbene concentration is lower than the upper value using the carbene scavenger, it can be determined that the increase of carbene has been suppressed.

[0094] Alternatively, in this invention, it can be determined that the increase of carbene has been suppressed when the carbene concentration is substantially zero within the refrigeration cycle. That is, when the carbene concentration within the refrigeration cycle is reduced to a level that can be considered an impurity of the working medium for the refrigeration cycle, and is in a state that is substantially free of carbene, it is considered that the carbene concentration is substantially zero, and it can be determined that the carbene concentration has been suppressed.

[0095] The upper limit of carbene concentration can be appropriately set according to various conditions, including the specific configuration of the refrigeration cycle or compressor, and is not particularly limited. As a representative upper limit, in at least one of the above-mentioned discharge region and sliding region, the upper limit of carbene concentration can be set to a mole fraction of 0.35 (mol / mol) or less.

[0096] According to the simulation results of the embodiments described later (Table 1), if the mole fraction of carbene is 0.4 (comparative example), the disproportionation reaction suppression fails at an initial temperature of 423 K and initial pressures of 0.6 MPa, 2.0 MPa, and 6.0 MPa. On the other hand, if the mole fraction of carbene is 0.3, the disproportionation reaction suppression succeeds at an initial temperature of 423 K and initial pressures of 0.6 MPa, 2.0 MPa, and 6.0 MPa.

[0097] As described below, when conducting a comprehensive study of the results of the examples, if the molar fraction of carbene is below 0.35, it is determined that the disproportionation reaction can be suppressed. As mentioned above, since carbene is readily generated in the discharge region or the sliding region, by ensuring that the upper limit of the carbene concentration, in molar fraction, is below 0.35 in at least one of the discharge region and the sliding region, adding a carbene scavenger to bring it below this upper limit can effectively suppress or alleviate the disproportionation reaction of fluoroolefins.

[0098] Furthermore, in this invention, not only is there an upper limit to the concentration of carbene, but the increase of carbene can also be suppressed by lowering the temperature or pressure at which carbene is easily generated due to the self-decomposition of fluoroolefins.

[0099] For example, in this invention, the increase of carbene can be suppressed by controlling the temperature of at least one of the discharge region and the sliding region below 700K. Alternatively, the increase of carbene can also be suppressed by controlling the pressure of at least one of the discharge region and the sliding region from a high temperature and high pressure state to below 2MPa.

[0100] In the discharge or sliding regions, when the upper temperature limit is below 700 K or the upper pressure limit is below 2 MPa, the high-temperature and high-pressure conditions required for the spontaneous decomposition reaction of fluoroolefins cannot be fully met. As a result, even if the fluoroolefins undergo spontaneous decomposition, carbene formation can be significantly suppressed. Consequently, the increase of carbene can be effectively suppressed in the discharge or sliding regions.

[0101] Furthermore, in the method for suppressing the disproportionation reaction of the working medium for refrigeration cycles according to the present invention, the specific method for capturing carbene is not necessarily limited to the above-described configuration. In the present invention, capturing carbene only requires the step of reacting the carbene scavenger described above with the carbene to convert the carbene into a singlet ground-state molecule without unpaired electrons. Alternatively, in the present invention, capturing carbene only requires the step of reacting the carbene scavenger described above with the carbene, allowing the carbene scavenger to act as a catalyst to convert two or more carbenes into singlet ground-state molecules without unpaired electrons.

[0102] Therefore, the present invention includes not only a method for suppressing the disproportionation reaction of the working medium for a refrigeration cycle, but also a method for capturing carbene present in the refrigeration cycle. Specifically, the carbene capturing method of the present invention can be configured such that, in a refrigeration cycle containing a composition for a refrigeration cycle, the composition for a refrigeration cycle (described later) contains a carbene capturing agent that has a higher reactivity with carbene than with substances other than carbene present in the refrigeration cycle, and that the carbene capturing agent reacts with carbene present in the refrigeration cycle, thereby capturing carbene present in the refrigeration cycle.

[0103] [Example of a refrigeration cycle system] Below, refer to Figure 4 A, Figure 4 The representative “freezing cycle system (freezing cycle apparatus)” shown in B illustrates a freezing cycle in which the method for suppressing the disproportionation reaction of the working medium for freezing cycle according to the present invention is applied.

[0104] The specific configuration of the refrigeration cycle system involved in this invention is not particularly limited, as long as it consists of components such as a compressor, condenser, expansion mechanism, and evaporator connected by piping. The specific applications of the refrigeration cycle system involved in this invention are also not particularly limited, including, for example, air conditioning units (air conditioners), refrigerators (household and commercial), dehumidifiers, display cabinets, ice makers, heat pump water heaters, heat pump washer-dryers, vending machines, etc.

[0105] As a representative example of the applicable refrigeration cycle system involved in this invention, an air conditioning device is described. Specifically, as follows... Figure 4 As schematically shown in the block diagram of A, the air conditioning device 10 according to this embodiment has an indoor unit 11 and an outdoor unit 12, and piping 13 connecting them. The indoor unit 11 has a heat exchanger 14, and the outdoor unit 12 has a heat exchanger 15, a compressor 16, and a pressure reducing device 17.

[0106] The heat exchanger 14 of the indoor unit 11 and the heat exchanger 15 of the outdoor unit 12 are connected in a loop via piping 13, thereby forming the refrigeration cycle involved in this invention. Specifically, the heat exchanger 14 of the indoor unit 11, the compressor 16, the heat exchanger 15 of the outdoor unit 12, and the pressure reducing device 17 are connected in a loop via piping 13. Furthermore, a four-way valve 18 for switching between cooling and heating is provided on the piping 13 connecting the heat exchanger 14, the compressor 16, and the heat exchanger 15. In addition, the indoor unit 11 has a blower (not shown), a temperature sensor, an operating unit, etc., and the outdoor unit 12 has a blower (not shown), a liquid receiver, etc. The piping 13 is also provided with various valve devices (including the four-way valve 18), filters, etc. (not shown).

[0107] The indoor unit 11 has a heat exchanger 14 that exchanges heat between indoor air drawn into the indoor unit 11 by the blower fan and the refrigerant flowing inside the heat exchanger 14. When heating, the indoor unit 11 delivers warmed air through heat exchange into the room; when cooling, it delivers cooled air through heat exchange into the room. The outdoor unit 12 has a heat exchanger 15 that exchanges heat between external gas drawn into the outdoor unit 12 by the blower fan and the refrigerant flowing inside the heat exchanger 15.

[0108] The specific configuration of the indoor unit 11 and the outdoor unit 12, or the heat exchanger 14 or 15, the compressor 16, the pressure reducing device 17, the four-way valve 18, the air supply fan, the temperature sensor, the operating unit, the blower, the liquid receiver, other valve devices, the filter, etc., is not particularly limited, and known configurations can be appropriately applied.

[0109] right Figure 4 An example of the operation of the air conditioning unit 10 shown in Figure A will be explained in detail. First, during cooling or dehumidification operation, the compressor 16 of the outdoor unit 12 compresses and discharges gaseous refrigerant, which is then sent to the heat exchanger 15 of the outdoor unit 12 via a four-way valve 18. The heat exchanger 15 allows heat exchange between the external gas and the gaseous refrigerant, causing the gaseous refrigerant to condense and liquefy. The liquefied liquid refrigerant is then depressurized by the pressure reducing device 17 and sent to the heat exchanger 14 of the indoor unit 11. In the heat exchanger 14, through heat exchange with the indoor air, the liquid refrigerant evaporates into gaseous refrigerant. This gaseous refrigerant returns to the compressor 16 of the outdoor unit 12 via the four-way valve 18. The compressor 16 compresses the gaseous refrigerant and discharges it back to the heat exchanger 15 via the four-way valve 18.

[0110] Additionally, during heating operation, the compressor 16 of the outdoor unit 12 compresses and discharges gaseous refrigerant, which is then sent to the heat exchanger 14 of the indoor unit 11 via the four-way valve 18. In the heat exchanger 14, the gaseous refrigerant condenses and liquefies through heat exchange with indoor air. The liquefied refrigerant is then depressurized by the pressure reducing device 17, becoming a two-phase refrigerant, which is then sent to the heat exchanger 15 of the outdoor unit 12. The heat exchanger 15 allows heat exchange between the external gas and the two-phase refrigerant, causing the two-phase refrigerant to evaporate and return to the compressor 16. The compressor 16 then compresses the gaseous refrigerant and discharges it back to the heat exchanger 14 of the indoor unit 11 via the four-way valve 18.

[0111] Furthermore, as another representative example of the applicable refrigeration cycle system (refrigeration cycle device) involved in this invention, a refrigerator is cited for illustration. Specifically, for example... Figure 4 As schematically shown in the block diagram of B, the refrigerator 20 according to this embodiment includes a compressor 21, a condenser 22, a pressure reducing device 23, an evaporator 24, and piping 25. In addition, the refrigerator 20 also includes a main body casing (not shown), a blower, an operating unit, and a control unit.

[0112] Compressor 21 compresses the refrigerant gas, making it a high-temperature, high-pressure gaseous refrigerant. Condenser 22 cools and liquefies the refrigerant. Pressure reducing device 23, for example, a capillary tube, reduces the pressure of the liquefied refrigerant (liquid refrigerant). Evaporator 24 evaporates the refrigerant, making it a low-temperature, low-pressure gaseous refrigerant. Compressor 21, condenser 22, pressure reducing device 23, and evaporator 24 are connected in a loop in sequence by piping 25 through which the refrigerant gas flows, thus forming a refrigeration cycle.

[0113] The configuration of the compressor 21, condenser 22, pressure reducing device 23, evaporator 24, piping 25, main body casing, blower, operating unit, control unit, etc., is not particularly limited, and known configurations can be appropriately applied. Alternatively, the refrigerator 20 may also have other known configurations besides these.

[0114] right ​ The operation of refrigerator 20 shown in Figure B will be specifically explained using an example. Compressor 21 compresses the gaseous refrigerant and discharges it to condenser 22. Condenser 22 cools the gaseous refrigerant into liquid refrigerant. The liquid refrigerant is depressurized by pressure reducing device 23 and sent to evaporator 24. In evaporator 24, the liquid refrigerant vaporizes by acquiring heat from the surrounding environment, becoming gaseous refrigerant and returning to compressor 21. Compressor 21 compresses the gaseous refrigerant and discharges it to condenser 22 again.

[0115] Such an air conditioning unit 10 or refrigerator 20 has a refrigeration cycle (refrigeration cycle system) constructed using the aforementioned refrigeration cycle working medium. The fluoroolefins used as a refrigerant component in the refrigeration cycle working medium have good properties and low ODP and GWP. Furthermore, as described above, this refrigeration cycle working medium contains a carbene scavenger.

[0116] Therefore, the carbene generated during the self-decomposition of fluorinated alkenes is captured by the carbene scavenger. Consequently, the increase of carbene can be effectively suppressed during refrigeration cycles, thus inhibiting or preventing the chain reaction of self-decomposition of fluorinated alkenes. This also allows for the suppression or mitigation of the disproportionation reaction of fluorinated alkenes.

[0117] [Working media and compositions for refrigeration cycles] The present invention also includes the aforementioned working medium for refrigeration cycles containing a carbene scavenger. Specifically, the working medium for refrigeration cycles according to the present invention, as a refrigerant component, as described above, contains a fluoroolefin that undergoes a disproportionation reaction, and may contain a carbene scavenger to capture the carbene generated accompanying the disproportionation reaction. Regarding specific carbene scavengers, as described above, any component whose reactivity with carbene is higher than its reactivity with substances other than carbene is acceptable. Representative examples include singlet ground-state molecules containing π electrons or non-shared electron pairs; ketones are a more specific example of such compounds.

[0118] Furthermore, in the working medium for refrigeration cycles according to the present invention, in addition to fluorinated olefins, difluoromethane (HFC32, R32, chemical formula: CH2F2) may also be contained as a refrigerant component. In this case, if fluorinated olefins are considered as the "main component (main refrigerant component)" of the refrigerant component in the working medium for refrigeration cycles according to the present invention, then difluoromethane is positioned as a "secondary component (secondary refrigerant component)" of the refrigerant component in the working medium for refrigeration cycles according to the present invention.

[0119] As mentioned above, difluoromethane has an ozone depletion potential (ODP) of 0 compared to currently used HCFCs (hydrochlorofluorocarbons) and exhibits excellent refrigeration performance.

[0120] Furthermore, in the working medium for the refrigeration cycle according to the present invention, refrigerant components other than difluoromethane may be included as auxiliary refrigerant components. Examples of such other auxiliary refrigerant components include: hydrofluorocarbons (HFCs) such as difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluoropropane, hexafluoropropane, heptafluoropropane, pentafluorobutane, and heptafluorocyclopentane; and hydrofluoroolefins (HFOs) such as monofluoropropylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, and hexafluorobutene, but there are no particular limitations.

[0121] In addition, as a secondary refrigerant component, saturated hydrocarbons such as ethane, n-propane, cyclopropane, n-butane, cyclobutane, isobutane (2-methylpropane), methylcyclopropane, n-pentane, isopentane (2-methylbutane), neopentane (2,2-dimethylpropane), and methylcyclobutane, or carbon dioxide, can also be used.

[0122] These secondary refrigerant components are known to have minimal impact on ozone layer depletion and global warming; therefore, they can be used in combination with fluorinated olefins, or with fluorinated olefins and difluoromethane, as refrigerant components. Other refrigerant components mentioned above can be used individually or in appropriate combinations of two or more.

[0123] The content of the auxiliary refrigerant component is not particularly limited. In this invention, as long as fluoroolefins are the main refrigerant component, the content of fluoroolefins in the working medium for the refrigeration cycle involved in this invention is greater than the content of the auxiliary refrigerant component.

[0124] However, in the working medium for the refrigeration cycle involved in this invention, it is very important to keep the GWP as low as possible. Specifically, the GWP is preferably 200 or less (GWP≤200), more preferably 150 or less (GWP≤150). When fluorinated olefins are used as the main refrigerant component and difluoromethane is used as a secondary refrigerant component, the upper limit of the difluoromethane content can be 30% or less by mass of the total amount of refrigerant-related components, or 25% or less by mass, or even 20% or less by mass.

[0125] When the content of difluoromethane is 30% by mass or less, the GWP of the working medium for refrigeration cycles can be 200 or less; when it is 20% by mass or less, the GWP of the working medium for refrigeration cycles can be 150 or less. Furthermore, there is no particular limitation on the lower limit value of difluoromethane. The working medium for refrigeration cycles according to the present invention may also be free of difluoromethane, therefore its content can be 0% by mass or more.

[0126] Furthermore, in this invention, the working medium for the refrigeration cycle may contain not only a carbene scavenger but also a disproportionation inhibitor. Examples of such disproportionation inhibitors include saturated hydrocarbons or haloalkanes.

[0127] Saturated hydrocarbons can be listed as hydrocarbons with 2 to 5 carbon atoms, such as ethane, n-propane, cyclopropane, n-butane, cyclobutane, isobutane (2-methylpropane), methylcyclopropane, n-pentane, isopentane (2-methylbutane), neopentane (2,2-dimethylpropane), and methylcyclobutane. Only one of these saturated hydrocarbons can be used, or two or more can be appropriately combined. A representative example of these saturated hydrocarbons is n-propane.

[0128] There are no particular limitations on halogenated alkanes that act as disproportionation inhibitors, as long as they have disproportionation inhibitory effects. Representative examples include halogenated alkanes with 1 or 2 carbon atoms. Specifically, examples include halogenated alkanes with 2 carbon atoms, namely halogenated ethane (ethane halide), and halogenated alkanes with 1 carbon atom, namely halogenated methane (methane halide).

[0129] Among halogenated alkanes with 1 or 2 carbon atoms, halogenated methanes can specifically be compounds having the structure shown in formula (1).

[0130] CH m X n … (1) In formula (1), X is a halogen atom selected from fluorine (F), chlorine (Cl), bromine (Br) and iodine (I), m is an integer greater than or equal to 0 and n is an integer greater than or equal to 1, and the sum of m and n is 4. When n is greater than or equal to 2, X is the same or different types of halogen atoms.

[0131] That is, the halomethane represented by formula (1) can be at least one of the following: monohalomethane represented by formula (11), dihalomethane represented by formula (12), trihalomethane represented by formula (13), and tetrahalomethane represented by formula (14). X in these halomethanes represented by formulas (11) to (14) 1 X 2 X 3 and X 4 Each halogen atom can be represented independently. Therefore, X 1 ~X 4 They can be halogen atoms of different kinds, or at least two of them can be of the same kind while the others are of different kinds, or they can all be halogen atoms of the same kind.

[0132] CH3X 1 … (11) CH2X 1 X 2 … (12) CHX 1 X 2 X 3 … (13) CX 1 X 2 X 3 X 4 … (14) Examples of halomethanes represented by formula (1) include (mono)iodomethane (CH3I), diiodomethane (CH2I2), dibromomethane (CH2Br2), monobromomethane (CH3Br), dichloromethane (CH2Cl2), chloroiodomethane (CH2ClI), dibromochloromethane (CHBr2Cl), tetraiodomethane (CI4), carbon tetrabromoside (CBr4), bromotrichloromethane (CBrCl3), dibromodichloromethane (CBr2Cl2), tribromofluoromethane (CBr3F), difluoroiodomethane (CHF2I), fluorodiiodomethane (CHFI2), difluorodiiodomethane (CF2I2), dibromodifluoromethane (CBr2F2), and trifluoroiodomethane (CF3I), but there are no particular limitations. Only one of these halomethanes may be used, or two or more may be used in appropriate combinations.

[0133] Among halogenated alkanes with 1 or 2 carbon atoms, halogenated ethanes can specifically be compounds having the structure shown in formula (2).

[0134] C2H p X q … (2) In formula (2), X is the same as the halomethane mentioned above, and is a halogen atom selected from F, Cl, Br, I. p is an integer greater than or equal to 0 and q is an integer greater than or equal to 1. The sum of p and q is 6. When q is greater than or equal to 2, X is the same or different types of halogen atoms.

[0135] In other words, the haloethane shown in formula (2) can be at least one of the following: monohaloethane shown in formula (21), dihaloethane shown in formula (22), trihaloethane shown in formula (23), tetrahaloethane shown in formula (24), pentahaloethane shown in formula (25), and hexahaloethane shown in formula (26).

[0136] The X in these halogenated ethanes represented by formulas (21) to (26) 1 X 2 X 3 X 4 X 5 and X 6 Each halogen atom can be represented independently. Therefore, X 1 ~X 6 The halogen atoms can be of different types, or at least two can be of the same type while the others are of different types, or all of them can be of the same type.

[0137] CH2X 1 CH3 … (21) CHX 1 X 2 CH3 … (22) CX 1 X 2 X 3 CH3 … (23) CX 1 X 2 X 3 CH2X 4 … (twenty four) CX 1 X 2 X 3 CHX 4 X 5 … (25) CX 1 X 2 X 3 CX 4 X 5 X 6 … (26) The specific ethane haloide shown in formula (2) is not particularly limited. Examples include 1,1,1-trifluoro-2-iodoethane (CF3CH2I), monoiodoethane (CH3CH2I), monobromoethane (CH3CH2Br), and 1,1,1-triiodoethane (CH3CI3). Only one of these ethane haloides may be used, or two or more may be used in appropriate combinations.

[0138] The working medium for refrigeration cycles involved in this invention can be used in conjunction with lubricating oil (refrigeration oil) that lubricates the compressor of the refrigeration cycle system for use in refrigeration cycle systems.

[0139] The working medium for refrigeration cycles according to the present invention, as described above, comprises a refrigerant and uses fluoroolefins (e.g., 1,1,2-trifluoroethylene, etc.) and difluoromethane that undergo disproportionation reactions, and also contains a carbene scavenger. Furthermore, in the present invention, when the working medium for refrigeration cycles is used in conjunction with lubricating oil, it can be considered as a composition for refrigeration cycles (or a composition containing the working medium) consisting of the refrigerant component, the carbene scavenger, the lubricating oil component, and other components. In the working medium for refrigeration cycles according to the present invention, the carbene scavenger can be mixed into the refrigerant component, but it may also be mixed into the lubricating oil component, depending on the circumstances.

[0140] The lubricating oil component contained in the composition for refrigeration cycles (used in conjunction with the working medium for refrigeration cycles) may appropriately use various lubricating oils known in refrigeration systems. Specific lubricating oils may include ester-based lubricating oils, ether-based lubricating oils, diol-based lubricating oils, alkylbenzene-based lubricating oils, fluorinated lubricating oils, mineral oils, and hydrocarbon-based synthetic oils, but there are no particular limitations. Only one of these lubricating oils may be used, or two or more may be appropriately combined.

[0141] In addition, various known additives other than disproportionation inhibitors can be added to the compositions for refrigeration cycles. Specific additives include various stabilizers, antioxidants, moisture traps, metal passivators, anti-wear agents, defoamers, leak detection substances, etc., but there are no particular limitations. Antioxidants are used to improve the thermal stability, oxidation resistance, and chemical stability of refrigerant components or lubricating oils. Moisture traps are used to remove moisture when it has entered the refrigeration cycle system, especially to inhibit changes in the properties of lubricating oils. Metal passivators are used to inhibit or prevent chemical reactions caused by the catalytic action of metal components. Anti-wear agents are used to reduce wear on sliding parts within the compressor, especially wear during high-pressure operation. Defoamers are specifically used to inhibit the formation of bubbles in the lubricating oil.

[0142] There are no particular limitations on the specific types of these additives, and known compounds may be used appropriately depending on various conditions. Furthermore, only one compound may be used as an additive, or two or more compounds may be used in appropriate combinations. Additionally, there are no particular limitations on the amount of these additives added; they may be added within known limits as long as they do not impair the properties of the working medium for refrigeration cycles or the refrigeration cycle composition containing the working medium as described in this invention.

[0143] In other words, the composition for freezing cycles involved in this invention only needs to contain a carbene scavenger as described above, which has a higher reactivity with carbene than with substances other than carbene. As described above, the carbene scavenger only needs to be a singlet ground-state molecule containing π electrons or non-shared electron pairs.

[0144] Furthermore, the composition for refrigeration cycling according to the present invention may also contain ethylene-based fluorinated olefins. These ethylene-based fluorinated olefins may be 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene, or monofluoroethylene, but are not particularly limited thereto.

[0145] Furthermore, the refrigeration cycle composition according to the present invention may also contain difluoromethane and saturated hydrocarbons. These saturated hydrocarbons may include n-propane. The refrigeration cycle composition according to the present invention may also contain haloalkanes having 1 or 2 carbon atoms. Additionally, the above-described refrigeration cycle system (refrigeration cycle apparatus) may contain (have) the above-described refrigeration cycle composition.

[0146] Example The present invention will be described in more detail based on embodiments and comparative examples, but the invention is not limited thereto. Various changes, modifications, and alterations can be made by those skilled in the art without departing from the scope of the invention. In the following embodiments, the simulation of the disproportionation reaction of fluoroolefins is carried out as described below.

[0147] (Simulation of disproportionation reaction) In the disproportionation reaction of 1,1,2-trifluoroethylene as a fluoroolefin, the equilibrium structure was calculated using density functional theory for all reactants and products, and the reaction pathway and intrinsic reaction pathway were determined using the Global Reaction Route Mapping (GRRM) method.

[0148] For the determined intrinsic reaction pathway, the reaction rates in the forward and reverse directions at various temperatures are calculated using transition state theory. The temperature dependence of the calculated reaction rates is then fitted using the extended Arrhenius equation.

[0149] Based on the obtained fitting parameters of the reaction rate, the reaction time evolution in a closed homogeneous reactor (CHR) was calculated in the multiphysics analysis platform ChemkinPro (product name, manufactured by Ansys Inc.).

[0150] (Example 1) Using the CHR method described above, under the conditions of initial temperature of 423 K, initial pressure of 0.6 MPa, 2.0 MPa and 6.0 MPa, and carbene concentration of 0.1 mole fraction (mol / mol), the mole fraction of 1,1,2-trifluoroethylene molecules and the carbene generated by its thermal decomposition were varied to simulate the reaction progression of 60 seconds.

[0151] Under each initial pressure, all reactants were converted into the final products (carbon, CF4, HF) within a specified time (within 60 seconds). A case where a sharp increase in pressure and temperature (indicating spontaneous reaction propagation) was observed was considered a failure of inhibition (×), while a case where partial conversion into products did not result in a sharp increase in pressure and temperature was considered a successful inhibition (○). The results are shown in Table 1.

[0152] (Example 2) The carbene concentration was set to a mole fraction of 0.2 (mol / mol), and simulations were performed in the same manner as in Example 1, evaluating inhibition failure or success at various initial pressures. The results are shown in Table 1.

[0153] (Example 3) The carbene concentration was set to a mole fraction of 0.3 (mol / mol), and simulations were performed in the same manner as in Example 1, evaluating inhibition failure or success at various initial pressures. The results are shown in Table 1.

[0154] (Comparative example) The carbene concentration was set to a mole fraction of 0.4 (mol / mol), and simulations were performed in the same manner as in Example 1, evaluating inhibition failure or success at various initial pressures. The results are shown in Table 1.

[0155] [Table 1] (Comparison of Examples 1-3 with Comparative Example 1) According to the results in Table 1, when the carbene concentration is 0.1–0.3 mol / mol, the disproportionation reaction can be effectively suppressed regardless of the initial pressure. However, when the carbene concentration is 0.4 mol / mol, the disproportionation reaction cannot be suppressed under any initial pressure.

[0156] In particular, in the simulations of Examples 1-3 and Comparative Example 1, even at the most stringent initial pressure of 6.0 MPa, successful suppression was achieved when the carbene concentration was 0.35 or less in mole fraction. Therefore, it can be seen that in the present invention, setting the upper limit of the carbene concentration to 0.35 or less is effective in the refrigeration cycle, especially in the compressor.

[0157] (Experimental system for disproportionation reaction) A pressure sensor for measuring the internal pressure of the pressure container, a thermocouple for measuring the internal temperature of the pressure container, and a discharge device for causing a discharge inside the pressure container are installed in a sealed pressure container (internal volume 50 mL).

[0158] In addition, a gas cylinder (HFO1123) containing 1,1,2-trifluoroethylene as a refrigerant (and 5% limonene (liquid phase) as a stabilizer) was connected to a pressure vessel in a way that allowed for pressure adjustment. A pressure sensor and thermometer installed in the pressure vessel were connected to a data logger. Thus, an experimental system for the disproportionation reaction was constructed.

[0159] (Comparative Example 2) In the above experimental system, 1,1,2-trifluoroethylene was introduced from the HFO1123 gas cylinder into the pressure vessel. Therefore, the content of 1,1,2-trifluoroethylene in the working medium for refrigeration cycling inside the pressure vessel was 100% by mass.

[0160] To initiate the disproportionation reaction of 1,1,2-trifluoroethylene, a discharge device was used to discharge at a voltage of 100V under conditions of 25°C and an internal pressure of 1.3 MPa. Afterwards, once the internal pressure and temperature had sufficiently decreased, the interior of the pressure vessel was inspected, confirming the generation of a considerable amount of smoke and the occurrence of the 1,1,2-trifluoroethylene disproportionation reaction.

[0161] (Example 4) In the above experimental system, 1,1,2-trifluoroethylene was introduced from the HFO1123 gas storage cylinder into the pressure-resistant container, and 1,1,1-trifluoroacetone (CF3-CO-CH3) was added at a content of 9.7% by mass as a disproportionation inhibitor.

[0162] In addition, the same procedure as in Comparative Example 2 was followed to induce discharge inside the pressure vessel, but no significant increase in pressure or temperature was observed. Subsequently, the interior of the pressure vessel was examined, and no disproportionation reaction of 1,1,2-trifluoroethylene was confirmed.

[0163] However, the present invention is not limited to the embodiments described above. Various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical solutions disclosed in different embodiments and multiple variations are also included within the technical scope of the present invention.

[0164] Furthermore, based on the foregoing description, those skilled in the art will be able to clearly understand the numerous improvements and other embodiments of the present invention. Therefore, the foregoing description is merely illustrative and is provided to inspire those skilled in the art to implement the present invention. Substantial changes can be made to the details of its structure and / or function without departing from the spirit of the invention.

[0165] (Postscript) Based on the descriptions of the various embodiments above, the following technologies are disclosed in this specification.

[0166] (Technology 1) A method for suppressing the disproportionation reaction of a working medium for a refrigeration cycle, comprising: in a refrigeration cycle in which a working medium for a refrigeration cycle containing a refrigerant component that undergoes a disproportionation reaction is circulated, using a carbene scavenger that has a higher reactivity with carbene than with substances other than carbene present in the refrigeration cycle, to scavenge the carbene generated by the disproportionation reaction of the refrigerant component and suppress the disproportionation reaction of the refrigerant component.

[0167] (Technology 2) A method for suppressing the disproportionation reaction of a working medium for refrigeration cycles as described in Technology 1, wherein the carbene comprises a mixture selected from CF2, CHF, and C. n At least one of F2 (where n is any integer of 2, 3, or 4).

[0168] (Technology 3) A method for suppressing the disproportionation reaction of a working medium for refrigeration cycles as described in Technology 1 or Technology 2, wherein, in capturing the carbene, the method includes a step in which the carbene capturing agent reacts with the carbene to convert the carbene into a singlet ground-state molecule without unpaired electrons.

[0169] (Technology 4) A method for suppressing the disproportionation reaction of a working medium for refrigeration cycles as described in Technology 1 or Technology 2, wherein, in capturing the carbene, the method includes a step in which the carbene scavenger reacts with the carbene to act as a catalyst, thereby converting two or more carbene into singlet ground-state molecules without unpaired electrons.

[0170] (Technology 5) A method for suppressing the disproportionation reaction of the working medium for a refrigeration cycle as described in any one of Technologies 1 to 4, wherein suppressing the disproportionation reaction of the refrigerant component is to suppress the increase of the carbene in the refrigeration cycle, and suppressing the increase of the carbene includes the steps of making the concentration of the carbene lower than a predetermined upper limit of the concentration of the carbene or making the concentration of the carbene substantially zero.

[0171] (Technology 6) A method for suppressing the disproportionation reaction of a working medium for a refrigeration cycle as described in any one of Technologies 1 to 5, wherein the refrigeration cycle has a compressor, the compressor includes a discharge region capable of discharge and a sliding region, the sliding region having a sliding portion of a plurality of sliding components that slide in contact with each other on their sliding surfaces, and suppressing the disproportionation reaction of the refrigerant components is to suppress the increase of the carbene present in at least one of the discharge region and the sliding region.

[0172] (Technology 7) A method for suppressing the disproportionation reaction of a working medium for a refrigeration cycle as described in Technology 6, wherein the mole fraction of the carbene present in at least one of the discharge region and the sliding region is 0.35 or less.

[0173] (Technology 8) A method for suppressing the disproportionation reaction of a working medium for a refrigeration cycle as described in Technology 7, wherein the increase of the carbene is suppressed by controlling the temperature of at least one of the discharge region and the sliding region to below 700K.

[0174] (Technology 9) A method for suppressing the disproportionation reaction of a working medium for a refrigeration cycle as described in Technology 7 or Technology 8, wherein the increase of the carbene is suppressed by controlling the pressure of at least one of the discharge region and the sliding region from a high temperature and high pressure state to below 2 MPa.

[0175] (Technology 10) A method for capturing carbene present in a freezing cycle, comprising: in a freezing cycle containing a freezing cycle composition, the freezing cycle composition contains a carbene capture agent whose reactivity with the carbene is higher than that with substances other than the carbene present in the freezing cycle, and capturing the carbene present in the freezing cycle by reacting the carbene capture agent with the carbene present in the freezing cycle.

[0176] (Technology 11) A composition for refrigeration cycling, comprising: a carbene scavenger having a higher reactivity with carbene than with substances other than carbene.

[0177] (Technology 12) The composition for cryogenic cycling as described in Technology 11, wherein the carbene trapping agent is a singlet ground-state molecule containing π electrons or non-shared electron pairs.

[0178] (Technology 13) The composition for refrigeration cycling as described in Technology 11 or Technology 12, wherein it further contains an ethylene-based fluoroolefin.

[0179] (Technology 14) The composition for refrigeration cycling as described in Technology 13, wherein the ethylene-based fluoroolefin is 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene or monofluoroethylene.

[0180] (Technology 15) The composition for refrigeration cycle as described in any one of Technologies 11 to 14, wherein it further comprises difluoromethane.

[0181] (Technology 16) The composition for refrigeration cycle as described in any one of Technologies 11 to 15, wherein it further comprises saturated hydrocarbons.

[0182] (Technology 17) The composition for refrigeration cycle as described in Technology 16, wherein the saturated hydrocarbon contains n-propane.

[0183] (Technology 18) The composition for refrigeration cycling as described in any one of Technologies 11 to 17, wherein it contains a haloalkane having 1 or 2 carbon atoms.

[0184] (Technology 19) A refrigeration cycle apparatus comprising a refrigeration cycle composition as described in any one of Technologies 11 to 18.

[0185] Industrial availability This invention is applicable to the field of working media used in refrigeration cycles, and is also widely applicable to refrigeration cycle systems such as air conditioning units (air conditioners), refrigerators (household and commercial), dehumidifiers, display cabinets, ice makers, heat pump water heaters, heat pump washer-dryers, and vending machines.

[0186] Symbol Explanation 10: Air conditioning unit (refrigeration cycle system); 11: Indoor unit; 12: Outdoor unit; 13: Piping; 14: Heat exchanger; 15: Heat exchanger; 16: Compressor; 17: Pressure reducing device; 18: Four-way valve; 20: Refrigerator (refrigeration cycle system); 21: Compressor; 22: Condenser; 23: Pressure reducing device; 24: Evaporator; 25: Piping; 31: Carbene; 32: Carbene scavenger (carbene direct reaction type); 33: Singlet ground state molecule; 34: Carbene scavenger (catalyst type); 161: Sealed container; 162: Electric motor section; 163: Compression mechanism section; 163A: First compression mechanism section ; 163B: Second compression mechanism; 164: Stator; 165: Rotor; 166: Rotating shaft; 167: Main bearing; 168: Secondary bearing; 169A: First piston; 169B: Second piston; 170: Liquid reservoir; 171A: First suction pipe; 171B: Second suction pipe; 172A: First compression chamber; 172B: Second compression chamber; 173: Airtight power terminal; 174: Wiring; 201: Discharge area; 201a: Reaction intermediate retention area; 201A: Discharge area; 201B: Discharge area; 202A: Sliding area; 202B: Sliding area; 202C: Sliding area.

Claims

1. A method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle, characterized by: in a refrigeration cycle in which a working medium for a refrigeration cycle containing a refrigerant component that undergoes disproportionation reaction is circulated, capturing a carbene generated by the disproportionation reaction of the refrigerant component with a carbene trapping agent having reactivity higher than that of the carbene with a substance other than the carbene present in the refrigeration cycle, and inhibiting the disproportionation reaction of the refrigerant component.

2. The method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to claim 1, characterized by:

3. The method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to claim 1 or 2, characterized by: in capturing the carbene, including a step of reacting the carbene trapping agent with the carbene to convert the carbene into a singlet ground state molecule having no unpaired electron. The carbene comprises at least one selected from CF2, CHF and C n F2, wherein n is any integer of 2, 3, 4.

4. The method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to claim 1 or 2, characterized by: in capturing the carbene, including a step of reacting the carbene trapping agent with the carbene to convert two or more carbene into a singlet ground state molecule having no unpaired electron, with the carbene trapping agent functioning as a catalyst.

5. The method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to claim 1 or 2, characterized by: inhibiting the disproportionation reaction of the refrigerant component is inhibiting an increase in the carbene in the refrigeration cycle, in inhibiting the increase in the carbene, including a step of making the concentration of the carbene lower than an upper limit value of the concentration of the carbene set in advance, or making the concentration of the carbene substantially 0.

6. The method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to claim 1 or 2, characterized by: the refrigeration cycle has a compressor, in the compressor, including a discharge region in which discharge occurs and a sliding region having a plurality of sliding members that slide in contact with each other on sliding surfaces thereof, inhibiting the disproportionation reaction of the refrigerant component is inhibiting an increase in the carbene present in at least one of the discharge region and the sliding region.

7. The method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to claim 6, characterized by: making the mole fraction of the carbene present in at least one of the discharge region and the sliding region 0.35 or less.

8. The method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to claim 7, characterized by: inhibiting the increase in the carbene by controlling the temperature of at least one of the discharge region and the sliding region to 700 K or less.

9. The method of inhibiting disproportionation reaction of a working medium for a refrigeration cycle according to claim 7, characterized by: inhibiting the increase in the carbene by controlling the pressure of at least one of the discharge region and the sliding region from a high-temperature high-pressure state to 2 MPa or less.

10. A method of capturing a carbene present in a refrigeration cycle, characterized by: in a refrigeration cycle in which a composition for a refrigeration cycle is circulated, ​ ​ ​ The composition for a refrigeration cycle contains a carbene-trapping agent having a reactivity higher than that of a substance other than the carbene present in the refrigeration cycle, The carbene-trapping agent traps a carbene present in the refrigeration cycle by reacting with the carbene present in the refrigeration cycle.

11. A composition for a refrigeration cycle, characterized by: containing a carbene-trapping agent having a reactivity higher than that of a substance other than the carbene.

12. The composition for a refrigeration cycle according to claim 11, characterized by: The carbene-trapping agent is a singlet ground state molecule containing π electrons or a lone pair of electrons.

13. The composition for a refrigeration cycle according to claim 11, characterized by: Further containing an ethylene-based fluoroolefin.

14. The composition for a refrigeration cycle according to claim 13, characterized by: The ethylene-based fluoroolefin is 1,1,2-trifluoroethylene, trans-1,2-difluoroethylene, cis-1,2-difluoroethylene, 1,1-difluoroethylene, tetrafluoroethylene or monofluoroethylene.

15. The composition for a refrigeration cycle according to claim 11, characterized by: Further containing difluoromethane.

16. The composition for a refrigeration cycle according to claim 11, characterized by: Further containing a saturated hydrocarbon.

17. The composition for a refrigeration cycle according to claim 16, characterized by: The saturated hydrocarbon contains n-propane.

18. The composition for a refrigeration cycle according to claim 11, characterized by: Containing a halogenated alkane having 1 or 2 carbon atoms.

19. A refrigeration cycle device, characterized by: Containing the composition for a refrigeration cycle according to claim 11.

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