Refrigeration oil, working fluid compositions for refrigeration equipment, and refrigeration systems

Abstract

This application relates to the field of refrigeration systems, disclosing a refrigeration oil, a working fluid composition for refrigeration machines, and a refrigeration system. By adding a specific type of surfactant, this application significantly reduces the surface tension of the refrigeration oil, improves its compatibility with refrigerants such as hydrofluorocarbons, and reduces oil film formation or oil residue in the refrigeration system. The refrigeration oil described in this application has suitable viscosity and solubility viscosity, meeting the normal operating requirements of the compressor, while also effectively inhibiting the formation of oil film on the heat exchanger surface, thereby improving heat exchange efficiency. Furthermore, this refrigeration oil has good lubricity, low-temperature fluidity, and thermochemical stability, which can promote the circulation of the refrigeration oil in the refrigeration system pipeline, improve oil return efficiency, and extend the compressor's service life.

Description

Technical Field

[0001] This application relates to the field of refrigeration systems, and more particularly to a refrigeration oil, a working fluid composition for refrigeration machines, and a refrigeration system. Background Technology

[0002] In refrigeration systems, refrigeration oil (lubricating oil) is a crucial lubricating medium for ensuring the normal operation of the compressor. Its main functions include lubricating the internal moving parts of the compressor, sealing the gap between the piston and cylinder, and carrying away heat generated during compression. However, in actual operation, when the refrigerant is compressed into high-pressure gas by the compressor pump and discharged from the compressor through the pipeline, it carries away some lubricating oil. Furthermore, existing lubricating oils such as mineral oil, alkylbenzene, synthetic ester POE, and polyether have poor compatibility with refrigerants, especially in systems using HFCs (such as R410A and R32), leading to uneven oil distribution within the system. Particularly in heat exchangers such as evaporators and condensers, due to the incompatibility between the refrigerant and refrigeration oil, the refrigeration oil easily forms a thick oil film on the inner surface of the heat exchanger. This oil film significantly increases the thermal resistance of the heat exchanger, reduces heat exchange efficiency, and consequently affects the overall refrigeration performance of the system. In addition, the oil that remains on the pipe wall cannot effectively flow back to the compressor. This is especially true in long pipes and large refrigeration systems, which can easily cause insufficient oil in the internal moving friction pairs of the compressor, leading to poor lubrication and thus reliability problems such as mechanical wear, temperature rise, or even compressor damage.

[0003] Currently, common solutions to the problem of refrigeration oil return include optimizing system design, adding oil return devices, or using refrigeration oils with better compatibility. However, these methods still have certain limitations in practical applications, such as high cost, complex structure, high requirements for system modification, or inability to fundamentally solve the impact of oil film on heat exchange efficiency. Therefore, there is an urgent need for a new technical solution that can effectively improve the distribution of refrigeration oil in the heat exchanger, reduce oil film formation, improve heat exchange efficiency, and simultaneously promote the return of refrigeration oil to the compressor, in order to improve the overall performance of the refrigeration system and the operational reliability of the compressor. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a refrigeration oil that can effectively improve the distribution of refrigeration oil in a heat exchanger, reduce oil film formation, improve heat exchange efficiency, and promote the return of refrigeration oil to the compressor.

[0005] Another object of this application is to provide a working fluid composition for refrigeration machines based on the refrigeration oil described in this application, as well as a refrigeration system.

[0006] To achieve all or part of the above objectives, as a first aspect of this application, a refrigeration oil is provided, comprising a base oil and a surfactant; The surface activity is selected from one or more of polyoxyethylene ether surfactants, polyoxyethylene ester surfactants, sulfonate surfactants, and alkoxybenzoate surfactants; The general structural formula of the polyoxyethylene ether surfactant is R1-O-(CH2-CH2-O). n1 -H, R1 is a C10~C20 straight-chain alkyl group, and n1 is a degree of polymerization of 2~25; The general structural formula of the polyoxyethylene ester surfactant is R2-CO-(O-CH2-CH2). n2 -OH, R1 is a C10~C20 straight-chain alkyl group, and n2 is the degree of polymerization of 1~25; The general structural formula of the sulfonate surfactant is R3-SO3. - Na + R3 is a C6-C20 straight-chain alkyl group or a C6-C20 straight-chain alkylphenyl group; The general structural formula of the alkoxybenzoate surfactant is R4-OC6H4COO - Na + R4 is a straight-chain alkyl group from C11 to C20.

[0007] Optionally, it includes 70-99.9% base oil and 0.1-15% surfactant by weight.

[0008] Optionally, the polyoxyethylene ether surfactant includes polyethylene glycol monolaurate, the polyoxyethylene ester surfactant includes polyethylene glycol monostearate, the sulfonate surfactant includes one or more of sodium dodecylbenzenesulfonate, sodium decaalkyl sulfonate, sodium dodecyl sulfonate, and sodium tetradecyl sulfonate, and the alkoxybenzoate surfactant includes one or more of sodium 4-dodecoxybenzoate, sodium 4-hexadecoxybenzoate, and sodium 4-octadecoxybenzoate.

[0009] Further optionally, it also includes additives selected from one or more of antioxidants, acid scavengers, metal deactivators, anti-wear agents, and anti-foaming agents.

[0010] Optionally, the antioxidant includes one or more of phenolic antioxidants and amine antioxidants; the acid scavenger includes one or more of epoxy compounds; the anti-wear agent includes one or more of alkyl phosphates and alkyl phosphates, dialkyl dithiophosphates, and phosphate esters; the antifoaming agent includes one or more of silicone-containing and non-silicone-containing antifoaming agents; and the metal deactivator includes one or more of benzotriazole and benzotriazole derivatives, thiadiazole and thiadiazole derivatives, and heterocyclic compounds.

[0011] Optionally, the additive is in the form of 0.1 to 15 parts by weight.

[0012] As a second aspect of this application, a fluid composition for a refrigeration machine is provided, comprising a refrigerant and the refrigeration oil described in this application.

[0013] Optionally, the refrigerant includes a hydrofluorocarbon refrigerant.

[0014] As a third aspect of this application, a refrigeration system is provided, comprising the fluid composition for a refrigeration machine described in this application.

[0015] Optionally, the refrigeration system includes a compressor, a condenser, an expansion valve, an evaporator, a distributor, and the fluid composition for refrigeration described in this application; the compressor, condenser, expansion valve, evaporator, distributor, and compressor are sequentially connected by pipelines to form a circulation system, and the fluid composition for refrigeration fills the compressor and circulates throughout the entire refrigeration system during operation.

[0016] This application significantly reduces the surface tension of refrigeration oil by adding specific types of surfactants, thereby improving its compatibility with refrigerants such as hydrofluorocarbons and reducing oil film formation or oil residue in the refrigeration system. The refrigeration oil described in this application has suitable viscosity and solubility viscosity, meeting the normal operating requirements of the compressor while effectively inhibiting oil film formation on the heat exchanger surface, thus improving heat exchange efficiency. Furthermore, this refrigeration oil possesses good lubricity, low-temperature fluidity, and thermochemical stability, promoting oil circulation in the refrigeration system piping, improving oil return efficiency, and extending compressor lifespan. Attached Figure Description

[0017] Figure 1 The diagram shown is a schematic diagram of the refrigeration system structure of this application; Icon labels: 11: Compressor 11; 111: First pipeline; 12: Condenser; 121: Second pipeline (heat dissipation pipeline); 13: Third pipeline; 14: Expansion valve; 141: Fourth pipeline; 15: Evaporator; 151: Evaporator pipeline; 152: Fifth pipeline; 16: Distributor; 161: Sixth pipeline. Detailed Implementation

[0018] This application discloses a refrigeration oil, a working fluid composition for refrigeration machines, and a refrigeration system. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this application. The products and processes described in this application have been described through preferred embodiments. Those skilled in the art can obviously modify or appropriately change and combine the products and processes described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this application. Obviously, the described embodiments are only some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application.

[0019] It should be noted that, in this document, relational terms such as "first" and "second," "step 1" and "step 2," and "(1)" and "(2)" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Moreover, the embodiments and features described in this application can be combined with each other without conflict.

[0020] Current technologies for improving the oil return performance and heat exchange efficiency of refrigeration systems typically involve adding oil return devices, oil return systems, or optimizing refrigerant channel design. These improvements are not only complex and costly, but also suffer from low oil return efficiency and unsatisfactory oil film control under extreme operating conditions.

[0021] In a first aspect of this application, a refrigeration oil containing a specific surfactant is provided to address the aforementioned problems. This refrigeration oil comprises a base oil and a surfactant, as well as additives added as needed. The surfactant in the refrigeration oil is a nonionic or anionic surfactant selected from one or more of polyoxyethylene ether surfactants, polyoxyethylene ester surfactants, sulfonate surfactants, and alkoxybenzoate surfactants. The refrigeration oil has low surface tension, good compatibility and chemical stability with refrigerants such as HFCs, and while meeting the normal operating requirements of the compressor, it can reduce oil film formation in the piping system, promote the return of refrigeration oil to the compressor, and improve the heat exchanger efficiency.

[0022] In some embodiments of this application, the general structural formula of the polyoxyethylene ether surfactant is R1-O-(CH2-CH2-O). n1 -H, R1 is a C10~C20 straight-chain alkyl group, for example, a straight-chain alkyl group with 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 C atoms; n1 is a degree of polymerization of 2~25, for example 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25; The general structural formula of the polyoxyethylene ester surfactant is R2-CO-(O-CH2-CH2). n2 -OH, R1 is a C10~C20 straight-chain alkyl group, for example, a straight-chain alkyl group with 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 C atoms; n2 is the degree of polymerization from 1 to 25; for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25; The general structural formula of the sulfonate surfactant is R3-SO3. - Na + R3 is a C6-C20 straight-chain alkyl or a C6-C20 straight-chain alkylphenyl; for example, a straight-chain alkyl with 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 C atoms, or a straight-chain alkylphenyl with 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 C atoms; The general structural formula of the alkoxybenzoate surfactant is R4-OC6H4COO - Na + R4 is a straight-chain alkyl group from C11 to C20.

[0023] In the process of determining suitable surfactants in this application, it was found that branched surfactants (such as sodium dioctyl sulfosuccinate) or other short-chain surfactants (≤7 carbons) (such as sodium heptasulfate) can reduce interfacial tension, but problems such as emulsification or sludge formation exist, and therefore their subsequent application effects were not evaluated.

[0024] The alkoxybenzoate surfactants described in this application can be prepared by referring to the synthetic methods described in existing literature: for example, referring to the literature "Facile synthesis of an organically-derivatized hexavanadate containing the remote amino group, TBA2[V6O] 13 The synthesis of trihydroxymethylaminomethane hexavanadate derivatives is described in "[(OCH2)3CNH2}2]" (Cryst Eng Comm, 2016, 18(22): 4042-4045). Then, the trihydroxymethylaminomethane hexavanadate derivatives are subjected to a catalytic amidation reaction with the corresponding long-chain alkoxybenzoic acid. Common amidation catalysts such as DMAP, 1-hydroxybenzotriazole (HOBT) / benzotriazole-1-yl-oxytripyrrolidinephosphine hexafluorophosphate (PyBOT) are used to obtain a series of alkoxybenzoate surfactants (the reaction principle is described in the master's thesis "Synthesis and Characterization of Amphiphilic Organic-Inorganic Hybrid Materials Based on Polyvanadate," pages 22-26). Based on the above existing reaction route, this application selects corresponding long-chain alkoxybenzoic acids, such as 4-dodecyloxybenzoic acid and 4-hexadecyloxybenzoic acid, to synthesize sodium 4-dodecyloxybenzoate and sodium 4-hexadecyloxybenzoate.

[0025] In some embodiments of this application, when the amount of surfactant is too low, the surface tension of the oil is high and the oil circulation rate is poor; while when the amount is too high, although the surface tension of the oil is low and the oil circulation rate is good, the surfactant will quickly separate and precipitate in the oil phase, failing to form an effective interface. For better compatibility, the amount of surfactant needs to be controlled to balance compressor reliability and system performance. The refrigeration oil, by mass percentage, comprises 70-99.9% base oil and 0.1-15% surfactant, totaling 100%. The mass percentage of the base oil can be selected from 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9% or any value between any two. The mass percentage of the surfactant can be selected from 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15% or any value between any two.

[0026] In some embodiments of this application, the polyoxyethylene ether surfactant includes polyethylene glycol monolaurate, with a degree of polymerization n1 preferably of 4 to 10, such as 4, 5, 6, 7, 8, 9, or 10; the polyoxyethylene ester surfactant includes polyethylene glycol monostearate, with a degree of polymerization n2 preferably of 1 to 7, such as 1, 2, 3, 4, 5, 6, or 7; the sulfonate surfactant includes one or more of sodium dodecylbenzenesulfonate, sodium decaalkylsulfonate, sodium dodecylsulfonate, and sodium tetradecylsulfonate; and the alkoxybenzoate surfactant includes one or more of sodium 4-dodecoxybenzoate, sodium 4-hexadecoxybenzoate, and sodium 4-octadecoxybenzoate.

[0027] In some embodiments of this application, the base oil includes one or more of mineral oil and synthetic oil; wherein, the synthetic oil includes one or more of polyalkylene glycol, polyvinyl ether, and polyol ester, and more specifically includes, but is not limited to, PVE, PAO, PAG, POE oils, etc., which provide basic lubrication performance.

[0028] In some embodiments of this application, the refrigeration oil further includes additives, which are selected from one or more of antioxidants, acid scavengers, metal deactivators, anti-wear agents, and anti-foaming agents. The additives constitute 0.1% to 15% of the refrigeration oil by mass, specifically 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, or any value between these two ranges. The additives, base oil, and surfactants total 100%. When multiple additives are used, the amount of each additive can be adjusted according to actual needs, and this application does not impose any restrictions.

[0029] In other embodiments of this application, the refrigeration oil may be further supplemented with antioxidants to improve its antioxidant properties. These antioxidants include, but are not limited to, phenolic antioxidants and amine antioxidants. The phenolic antioxidants include, but are not limited to, 2,6-hydroxyl-2-ethylhexylene (HJ-2,HJ-3)-ethylhexylene (HJ-3 ... Second Uncle Ding Ji p-Cresol (DBPC), 2,6 Second Uncle Ding Ji Phenol, 4,4' Methylenebis(2,6) Second Uncle Ding Ji Phenol, etc. The amine-based antioxidants include, but are not limited to, phenyl-α-naphthylamines, dialkylated diphenylamines, etc. One antioxidant may be used alone, or two or more may be used in combination.

[0030] In other embodiments of this application, the refrigeration oil may be further supplemented with acid scavengers to improve stability. The acid scavengers include, but are not limited to, epoxy compounds (epoxy-based acid scavengers). These epoxy compounds include, but are not limited to, glycidyl ether type epoxy compounds, glycidyl ester type epoxy compounds, aryl ethylene oxide compounds, alkyl ethylene oxide compounds, alicyclic ethylene oxide compounds, epoxidized fatty acid monoesters, epoxidized vegetable oils, etc. These acid scavengers may be used alone, or two or more may be used in combination.

[0031] In other embodiments of this application, the refrigeration oil may be further supplemented with anti-wear additives to improve stability. These anti-wear additives include, but are not limited to, one or more of alkyl phosphates and alkyl phosphates, dialkyl dithiophosphates, and phosphate esters; for example, triphenyl phosphate, tricresyl phosphate, diphenyl-p-tert-butyl phosphate, etc. These secondary anti-wear additives may be used alone, or in combination of two or more.

[0032] In other embodiments of this application, the refrigeration oil composition may be further supplemented with an antifoaming agent to improve its antifoaming performance. The antifoaming agents include, but are not limited to, silicone-based and non-silicone-based agents. Silicone-based antifoaming agents include, but are not limited to, polydimethylsiloxane. Non-silicone-based antifoaming agents include, but are not limited to, homopolymers or copolymers of acrylates or methacrylates. These antifoaming agents may be used alone or in combination of two or more.

[0033] In other embodiments of this application, the refrigeration oil composition may be further supplemented with metal deactivators to protect the metals in the refrigeration system from corrosion. The metal deactivators include one or more of benzotriazole and benzotriazole derivatives, thiadiazole and thiadiazole derivatives, and heterocyclic compounds. The benzotriazole and benzotriazole derivatives include, but are not limited to, methylbenzazole (TTZ), N,N'-dialkylaminomethylenebenzazole, N,N'-di(2-ethylhexyl)-methyl-1H-benzazole-1-methylamine, etc.; the thiadiazole and thiadiazole derivatives include, but are not limited to, thiadiazole polysulfides, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium, etc. These metal deactivators may be used alone or in combination of two or more.

[0034] In a second aspect of this application, a fluid composition for a refrigeration unit is provided, comprising a refrigerant and the refrigeration oil described in this application.

[0035] In some embodiments of this application, the refrigerant includes hydrofluorocarbon refrigerants (HFCs). These HFCs include, but are not limited to, HFC-23 (R-23, trifluoromethane), HFC-32 (R-32, difluoromethane), HFC-125 (R-125, pentafluoroethane), HFC-134 (R134, 1,1,2,2-tetrafluoroethane), and HFC-134a (R-134a, 1,1,1,2-tetrafluoroethane).

[0036] In a third aspect of this application, a refrigeration system is provided, comprising the fluid composition for a refrigeration machine described in this application.

[0037] In some embodiments of this application, the refrigeration system includes a compressor, a condenser, an expansion valve, an evaporator, a distributor, and the refrigeration fluid composition described in this application; the compressor, condenser, expansion valve, evaporator, distributor, and compressor are sequentially connected by pipelines to form a circulation system, and the refrigeration fluid composition fills the compressor and circulates throughout the entire refrigeration system during operation. A schematic diagram is shown below. Figure 1 .

[0038] by Figure 1As an example, the refrigeration system of this application is further explained. During operation, the high-temperature, high-pressure gas discharged from the compressor 11 contains refrigerant oil, resulting in a reduced oil content. The discharged oil flows with the refrigerant and the first pipe 111 into the condenser 12. Excessive oil accumulation or adhesion to the heat dissipation pipes 121 in the condenser 12 leads to a decrease in heat exchange efficiency. The oil in this application, with its low surface tension, exhibits lower adhesion to the pipes, forming a thinner oil film. Furthermore, the heat dissipation pipes 121 have a higher temperature and lower oil viscosity, facilitating flow under refrigerant circulation. After flowing through the expansion valve 14 via the third pipe 13, the refrigerant oil in the fourth pipe 141 is in a low-temperature gas-liquid mixture state. Although the evaporator pipes 151 in the evaporator 15 have an even lower temperature and higher oil viscosity, the low surface tension reduces the oil circulation rate and weakens the adhesion between the oil and the pipe wall, resulting in a thinner oil film and thus improving heat exchange efficiency. Finally, the oil flows through the fifth pipe 152 to the distributor 16, and under the action of gravity and airflow, it returns to the oil sump of the compressor 11 through the sixth pipe 161, realizing the system circulation and return of the refrigeration oil.

[0039] In the comparative experiments provided in this application, unless otherwise specified, all experimental conditions and materials remain consistent to ensure comparability. Furthermore, all materials used in this application are commercially available.

[0040] The following provides a further description of a refrigeration oil, a working fluid composition for refrigeration machines, and a refrigeration system provided in this application.

[0041] Example 1: Base oil (Pentaerythritol isooctanoic acid-isononanoic acid mixed ester POE68-GL): 91.25%; Sodium 4-dodecyloxybenzoate: 5.20%; Antioxidant (2,6-di-tert-butyl-p-cresol BHT): 0.50%; Acid scavenger (ethylene oxide methyl neodecanoate E-10P): 1.0%; Metal deactivator (IRGAMET® 39): 1.0%; Anti-wear agent (trimethylbenzene phosphate T306): 1.0%; Antifoaming agent (polydimethylsilane PMX-200): 0.05%; Example 2: Base oil: 92.25%; Sodium 4-dodecyloxybenzoate: 4.20%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0042] Example 3: Base oil: 92.95%; Sodium dodecylbenzenesulfonate: 3.50%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0043] Example 4: Base oil: 91.45%; Sodium dodecylbenzenesulfonate: 5%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0044] Example 5: Base oil: 93.65%; Polyethylene glycol monostearate (n=4): 2.8%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0045] Example 6: Base oil: 91.65%; Polyethylene glycol monostearate (n=4): 4.8%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0046] Example 7: Base oil: 95.45%; Polyethylene glycol monolaurate (n=4): 1.50%; Antioxidant: 0.50%; Acid scavenger: 0.5%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0047] Example 8: Base oil: 92.45%; Polyethylene glycol monolaurate (n=4): 4.50%; Antioxidant: 0.50%; Acid scavenger: 0.5%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0048] Example 9: Base oil: 87.45%; Polyethylene glycol monolaurate (n=4): 9.0%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0049] Example 10: Base oil: 92.45%; Sodium 4-hexadecyloxybenzoate: 4.50%; Antioxidant: 0.50%; Acid scavenger: 0.50%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0050] Example 11: Base oil: 87.45%; Sodium 4-hexadecyloxybenzoate: 9.0%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0051] Comparative Example 1: Base oil: 96.45%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0052] Comparative Example 2: Base oil: 80.45%; Sodium 4-hexadecyloxybenzoate: 16.0%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0053] Comparative Example 3: Base oil: 96.40%; Sodium 4-hexadecyloxybenzoate: 0.05%; Antioxidant: 0.50%; Acid scavenger: 1.0%; Metal deactivator: 1.0%; Anti-wear agent: 1.0%; Antifoaming agent: 0.05%; The selection of each component is the same as in Example 1.

[0054] Experimental example: The examples and comparative examples were tested for various indicators when used with R32 refrigerant as working fluids. The results are shown in Table 1 and Table 2 below. Table 1

[0055] Table 2

[0056] According to the results in Tables 1 and 2, the surface tension of the refrigeration oil composition is significantly affected by the surfactant. When the surfactant content increases within a certain range, as in Examples 1-2, 3-4, and 5-6, both the surface tension and the oil circulation rate of the refrigeration oil system decrease accordingly. In particular, the oil circulation rate values ​​of Examples 10-11 and Comparative Examples 2-3 show a clear correlation with the surfactant content and surface tension changes in their oils. Furthermore, Comparative Example 1, which does not contain surfactant, exhibits high surface tension and a relatively high oil circulation rate. It is noteworthy that within a certain range, the addition of surfactants (as in Examples 1-2, 3-4, and 5-6, where different amounts and types of surfactants showed essentially consistent dissolution viscosity test data, and friction test data showed no significant difference in average wear scar diameter) does not affect the lubrication performance of the refrigeration oil composition. However, it is necessary to control the amount of surfactant used. For example, in Comparative Example 2, when the surfactant content exceeds 15%, although the surface tension of the oil is low and the oil circulation rate is good, the surfactant will rapidly separate and precipitate in the oil phase, failing to form an effective interface. Meanwhile, in Comparative Example 3, when the surfactant content was below 0.1%, the oil exhibited high surface tension and poor oil circulation rate. For better compatibility, the surfactant content needs to be controlled to balance compressor reliability and system performance. Furthermore, the average wear scar diameter of the refrigeration oil compositions in Examples 1-7 and Comparative Example 1 (which did not contain surfactant) showed no significant difference, indicating that the addition of surfactant does not affect lubrication performance.

[0057] Furthermore, according to the industry standard GB / T 5773 for performance testing of positive displacement refrigerant compressors, the compressor performance of the oil was tested using the "Rotor Compressor Performance Test Method". The refrigeration performance test results showed that the refrigeration capacity of Examples 1-11 was increased by 0.5-2% compared to Comparative Examples 1-3, demonstrating that the refrigeration oil provided in this application significantly improves the system's performance.

[0058] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A refrigeration oil, characterized in that, Including base oils and surfactants; The surface activity is selected from one or more of polyoxyethylene ether surfactants, polyoxyethylene ester surfactants, sulfonate surfactants, and alkoxybenzoate surfactants; The general structural formula of the polyoxyethylene ether surfactant is R1-O-(CH2-CH2-O). n1 -H, R1 is a C10~C20 straight-chain alkyl group, and n1 is a degree of polymerization of 2~25; The general structural formula of the polyoxyethylene ester surfactant is R2-CO-(O-CH2-CH2). n2 -OH, R1 is a C10~C20 straight-chain alkyl group, and n2 is the degree of polymerization of 1~25; The general structural formula of the sulfonate surfactant is R3-SO3. - Na + R3 is a C6-C20 straight-chain alkyl group or a C6-C20 straight-chain alkylphenyl group; The general structural formula of the alkoxybenzoate surfactant is R4-OC6H4COO - Na + R4 is a straight-chain alkyl group from C11 to C20.

2. The refrigeration oil according to claim 1, characterized in that, It comprises 70-99.9% base oil and 0.1-15% surfactant by weight percentage.

3. The refrigeration oil according to claim 1, characterized in that, The polyoxyethylene ether surfactants include polyethylene glycol monolaurate ether; the polyoxyethylene ester surfactants include polyethylene glycol monostearate; the sulfonate surfactants include one or more of sodium dodecylbenzenesulfonate, sodium decaalkyl sulfonate, sodium dodecyl sulfonate, and sodium tetradecyl sulfonate; and the alkoxybenzoate surfactants include one or more of sodium 4-dodecoxybenzoate, sodium 4-hexadecoxybenzoate, and sodium 4-octadecoxybenzoate.

4. The refrigeration oil according to any one of claims 1-3, characterized in that, It also includes additives, which are selected from one or more of antioxidants, acid scavengers, metal deactivators, anti-wear agents, and anti-foaming agents.

5. The refrigeration oil according to claim 4, characterized in that, The antioxidants include one or more of phenolic antioxidants and amine antioxidants; the acid scavengers include one or more of epoxy compounds; the anti-wear agents include one or more of alkyl phosphates and alkyl phosphates, dialkyl dithiophosphates, and phosphate esters; the antifoaming agents include one or more of silicone-containing and non-silicone-containing antifoaming agents; and the metal deactivators include one or more of benzotriazole and benzotriazole derivatives, thiadiazole and thiadiazole derivatives, and heterocyclic compounds.

6. The refrigeration oil according to claim 4, characterized in that, The additive is present in parts by weight of 0.1 to 15 parts.

7. A fluid composition for a refrigeration unit, characterized in that, It includes refrigerant and refrigeration oil as described in any one of claims 1-6.

8. The fluid composition for a refrigeration unit according to claim 7, characterized in that, The refrigerant includes hydrofluorocarbon refrigerants.

9. A refrigeration system, characterized in that, Includes the fluid composition for refrigeration machines as described in claim 7 or 8.

10. The refrigeration system according to claim 9, characterized in that, The system includes a compressor, a condenser, an expansion valve, an evaporator, a distributor, and a fluid composition for refrigeration as described in claim 7 or 8; the compressor, condenser, expansion valve, evaporator, distributor, and compressor are sequentially connected by pipelines to form a circulation system, and the fluid composition for refrigeration fills the compressor and circulates throughout the refrigeration system.

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