EP-4737532-A1 - METHOD FOR SUPPRESSING DISPROPORTIONATION REACTION OF WORKING MEDIUM FOR REFRIGERATION CYCLES, WORKING MEDIUM FOR REFRIGERATION CYCLES, AND REFRIGERATION CYCLE DEVICE

Abstract

Disclosed is a method of inhibiting a disproportionation reaction of a refrigeration-cycle working medium for a refrigeration cycle in which the refrigeration-cycle working medium circulates, the refrigeration-cycle working medium including a refrigerant component that causes the disproportionation reaction, the method including, in the refrigeration cycle, inhibiting the disproportionation reaction of the refrigerant component by capturing a carbene, generated by the disproportionation reaction of the refrigerant component, by a carbene scavenger having higher reactivity with the carbene than substances existing in the refrigeration cycle other than the carbene.

Inventors

• TSUNOYAMA, HIRONORI
• SAKATA, NAOYA
• NAGAO, NOBUAKI
• MURAKAMI, HIKARU
• HASHIMOTO, TAKAHIKO

Assignees

• Panasonic Intellectual Property Management Co., Ltd.

Dates

Publication Date

20260506

Application Date

20240625

Claims (19)

1. A method of inhibiting a disproportionation reaction of a refrigeration-cycle working medium for a refrigeration cycle in which the refrigeration-cycle working medium circulates, the refrigeration-cycle working medium including a refrigerant component that causes the disproportionation reaction, the method comprising in the refrigeration cycle, inhibiting the disproportionation reaction of the refrigerant component by capturing a carbene, generated by the disproportionation reaction of the refrigerant component, by a carbene scavenger having higher reactivity with the carbene than substances existing in the refrigeration cycle other than the carbene.
2. The method according to claim 1, wherein the carbene includes at least one selected from the group consisting of CF 2 , CHF, and C n F 2 (n is an integer of 2, 3, or 4).
3. The method according to claim 1 or 2, wherein capturing the carbene includes a process in which the carbene scavenger reacts with the carbene to convert the carbene into a singlet ground-state molecule which does not include an unpaired electron.
4. The method according to claim 1 or 2, wherein capturing the carbene includes a process in which the carbene scavenger reacts with the carbene and acts as a catalyst to convert two or more carbenes into a singlet ground-state molecule which does not include an unpaired electron.
5. The method according to claim 1 or 2, wherein: inhibiting the disproportionation reaction of the refrigerant component includes inhibiting an increase of the carbene in the refrigeration cycle; and inhibiting the increase of the carbene includes a process in which a concentration of the carbene falls below a preset upper limit of the concentration of the carbene or a process in which the concentration of the carbene is set to practically zero.
6. The method according to claim 1 or 2, wherein: the refrigeration cycle includes a compressor; the compressor includes an electric discharge region where electric discharge occurs and a slide region including a slide portion where a plurality of slide members slide in a state where sliding surfaces thereof are in contact with each other; and inhibiting the disproportionation reaction of the refrigerant component includes inhibiting an increase of the carbene existing in at least one of the electric discharge region or the slide region.
7. The method according to claim 6, wherein a mole fraction of the carbene existing in at least one of the electric discharge region or the slide region is set to 0.35 or less.
8. The method according to claim 7, wherein the increase of the carbene is inhibited by controlling a temperature in at least one of the electric discharge region or the slide region to 700 K or less.
9. The method according to claim 7, wherein the increase of the carbene is inhibited by controlling pressure in at least one of the electric discharge region or the slide region from a high-temperature high-pressure state to 2 MPa or less.
10. A method of capturing a carbene existing in a refrigeration cycle including a refrigeration-cycle composition, the refrigeration-cycle composition including a carbene scavenger having higher reactivity with the carbene than substances existing in the refrigeration cycle other than the carbene, the method comprising capturing the carbene existing in the refrigeration cycle by making the carbene scavenger react with the carbene existing in the refrigeration cycle.
11. A refrigeration-cycle composition comprising a carbene scavenger having higher reactivity with a carbene than substances other than the carbene.
12. The refrigeration-cycle composition according to claim 11, wherein the carbene scavenger is a singlet ground-state molecule including a π electron or an unshared electron pair.
13. The refrigeration-cycle composition according to claim 11, further comprising ethylene based fluoroolefin.
14. The refrigeration-cycle composition according to claim 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.
15. The refrigeration-cycle composition according to claim 11, further comprising difluoromethane.
16. The refrigeration-cycle composition according to claim 11, further comprising saturated hydrocarbon.
17. The refrigeration-cycle composition according to claim 16, wherein the saturated hydrocarbon includes n-propane.
18. The refrigeration-cycle composition according to claim 11, comprising haloalkane including one or two carbon atoms.
19. A refrigeration cycle apparatus comprising the refrigeration-cycle composition according to claim 11.

Description

Technical Field The present invention relates to a method of inhibiting a refrigeration-cycle working medium which can effectively inhibit or mitigate a disproportionation reaction of fluoroolefin (fluoroalkene), such as 1,1,2-trifluoroethylene, and a refrigeration-cycle working medium which uses this method. Background Art As a refrigeration-cycle working medium (a refrigerant or a heat medium), the use of fluoroolefin having an ozone depletion potential (ODP) of 0 and a lower global warming potential (GWP), especially hydrofluoroolefin (HFO), has been recently proposed. Known as representative HFOs are, for example, 1,1,2-trifluoroethylene (HFO1123) and difluoroethylene (HFO1132). The HFOs are lower in stability than conventional HFCs (hydrofluorocarbons) and the like. Therefore, the HFOs hardly remain in the atmosphere. It is also known that since the stability of the HFO is low, a self-polymerization reaction which is called a disproportionation reaction tends to occur (such reaction is hereinafter referred to as the disproportionation reaction). The disproportionation reaction tends to occur by being induced by, for example, heat generated during the use of the refrigeration-cycle working medium. In addition, it is also known that since large heat dissipation is caused by the occurrence of the disproportionation reaction, the disproportionation reactions occur successively. As a result, a large amount of soot is generated, and this may deteriorate the reliability of a refrigeration cycle system or the reliability of a compressor and the like constituting the refrigeration cycle system. For example, PTL 1 proposes that when the 1,1,2-trifluoroethylene is used as a refrigerant component of the refrigeration-cycle working medium, a radical scavenger be used as a component (disproportionation inhibitor) that inhibits the disproportionation reaction of the 1,1,2-trifluoroethylene. As examples of the specific radical scavenger, PTL 1 describes [1] a compound including a C-X (where X denotes Cl, Br, or I) bond, in which the bond energy of the C-X bond is equal to or less than the bond energies of other bonds in the molecule, [2] CX4 (where X denotes Cl, Br, or I, and four Xs are the same as each other), and [3] Rf-X (where Rf denotes a perfluoroalkyl group including 1 to 6 carbon atoms, and X denotes Cl, Br, or I). Citation List Patent Literature PTL 1: Japanese Patent No. 6455506 Summary of Invention Technical Problem However, according to further studies by the present inventors, it was found that there is a possibility that the use of the radical scavenger as described in PTL 1 cannot effectively inhibit or mitigate the disproportionation reaction of the fluoroolefin, such as the 1,1,2-trifluoroethylene. The present invention was made to solve the above problem, and an object of the present invention is to provide a new method of effectively inhibiting or mitigating a disproportionation reaction of fluoroolefin in a refrigeration-cycle working medium which contains the fluoroolefin as a refrigerant component. Solution to Problem The present inventors have diligently studied to solve the above problem. As a result, the present inventors have uniquely found that among substances generated in association with the disproportionation reaction of the fluoroolefin, a carbene, which has not attracted attention so far, may be involved in the chain progression of the disproportionation reaction. Thus, the present invention has been made. To solve the above problem, a method of inhibiting a disproportionation reaction of a refrigeration-cycle working medium according to the present disclosure is a method of inhibiting a disproportionation reaction of a refrigeration-cycle working medium for a refrigeration cycle in which the refrigeration-cycle working medium circulates, the refrigeration-cycle working medium including a refrigerant component that causes the disproportionation reaction, the method including, in the refrigeration cycle, inhibiting the disproportionation reaction of the refrigerant component by capturing a carbene, generated by the disproportionation reaction of the refrigerant component, by a carbene scavenger having higher reactivity with the carbene than substances existing in the refrigeration cycle other than the carbene. According to the above configuration, the carbene, which has been found to be involved in the chain progression of the disproportionation reaction of the refrigerant component, is captured by the carbene scavenger. Thus, since the increase of the carbene in the refrigeration cycle can be effectively inhibited, the disproportionation reaction of the refrigerant component can be inhibited or mitigated. Especially, it was found that: in the induction stage immediately before the chain progression of the self-decomposition of the refrigerant component in the disproportionation reaction of the refrigerant component, the carbene is gradually generated and accumulates; and when the conc