JPH10195426A - Working fluid for refrigerator and refrigerator using the working fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject medium excellent in abrasion resistance by formulating a perfluoroalkylcarboxylic acid glyceride as a lubricity-improving agent to a working fluid for a refrigerator that comprises a fluorinated hydrocarbon refrigerant and a refrigerating machine oil. SOLUTION: This working fluid for refrigerator is prepared by formulating (A) mono-, di- or tri-glyceride of perfluoroalkylcarboxylic acid or their mixture to (B) a fluorinated hydrocarbon refrigerant such as difluoromethane or 1,1,1,1- tetrafluoroethene and (C) a working fluid for refrigeration such as polyol ester or a naphthenic mineral oil. The component A is, for example, pefluorobutanoic acid monoglyceride and its amount is preferably 0.1-1wt.% based on the component C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working medium for a refrigerant compression refrigeration system for a refrigerator and an air conditioner, and a refrigeration system using the medium.

[0002]

2. Description of the Related Art At present, the refrigerant of a refrigeration system is CFC12.
(Dichlorodifluoromethane) and HCFC22 (monochlorodifluoromethane) are used.
(Chlorofluorocarbon) -based refrigerants and HCFC (hydrochlorofluorocarbon) -based refrigerants have been completely abolished from the viewpoint of environmental protection. These alternative refrigerants include HFC (hydrofluorocarbon) [fluorohydrocarbon] type refrigerants that do not contain chlorine in the molecule and have a boiling point close to the boiling point of the currently used refrigerants, and a mixture of two or more of them. Refrigerants are mentioned.

[0003] Refrigerating machine oil is used in compressors for refrigerating and air-conditioning machines such as refrigerators, room air conditioners, package air conditioners, and refrigerating machines, and plays a role in lubrication, sealing, and cooling of sliding parts thereof. In recent years, compressors have been
Low noise and high efficiency are required, and the use conditions of refrigeration oil are becoming severer. For this reason, a refrigerating machine oil excellent in lubricity, especially in abrasion resistance is required from the viewpoint of securing the reliability of the compressor. Refrigeration oils are widely used because naphthenic and paraffinic mineral oils and alkylbenzenes have good compatibility with CFC and HCFC refrigerants. But,
These refrigerating machine oils do not dissolve in the HFC-based refrigerant at all. Accordingly, polyol esters, which are fatty synthetic oils having a polar group in the molecule, have been developed as refrigerating machine oils which are compatible with them, and are disclosed in JP-A-62-13912 and JP-A-3-505602.
And JP-A-4-183788.

[0004] Further, since the HFC-based refrigerant does not contain chlorine in the molecule, the lubricating effect of the refrigerant itself cannot be expected at all as compared with the conventional refrigerant. Therefore, further lubricity is required for the refrigerating machine oil.

Various additives are used in general refrigerating machine oil, and a lubricity improver is one of them. As a lubricity improver for a mineral oil-based refrigerating machine oil, for example, tertiary phosphate phosphorus compounds such as triphenyl phosphate and tricresyl phosphate are known (edited by Toshio Sakurai, Petroleum Product Additives, Koshobo, May 15, 1973). Further, lubricating oil improvers for refrigerating machine oil compatible with HFC-based refrigerants include (1) secondary phosphite and acid phosphite (JP-A-4-28792), and (2) phosphoric acid of polyoxyalkylene alkyl ether. Esters (JP-A-62-27929)
No. 5) and (3) amine salts of secondary phosphites or acid phosphites (JP-A-63-90597;
3-39400) and (4) an organic molybdenum compound (JP-A-5-39494). However, none of these additives provide sufficient effects in terms of ensuring wear resistance and reliability. In addition, heat resistance stability and solubility in a fluorocarbon-based refrigerant or refrigerating machine oil are inferior, so that there are drawbacks such as lowering the efficiency of the refrigeration cycle and lowering the reliability of the compressor.

[0006]

The refrigerant compressors for refrigerators and air conditioners include scroll, reciprocating, screw, rotary type equal displacement compressors and turbo type compressors. FIG. 1 shows a schematic structure of a scroll compressor as an example of the compression means.

As shown in FIG. 1, the compressor comprises a spiral wrap 5 standing upright on an end plate 3 of a fixed scroll member 1, and end plates 4 and wraps 6 having substantially the same shape as the fixed scroll member 1.
The orbiting scroll member 2 is formed with a wrap 5 and a wrap 6 facing each other and meshed with each other to form a compression mechanism. To make a swirl motion. Of the compression chambers 8 (8a, 8b,...) Formed by the fixed scroll member 1 and the orbiting scroll member 2, the outermost compression chamber has both scrolls while the volume gradually decreases with the orbital movement. Member 1,
Move towards the center of 2.

When the compression chambers 8a and 8b reach near the centers of the scroll members 1 and 2, the compression chambers 8a and 8b communicate with the discharge port 9, and the compressed gas in the compression chambers is discharged and fixed. The gas passes through the scroll member 1 and a gas passage (not shown) provided in the frame 10 to reach the inside of the compression container 11 at the lower part of the frame, and is discharged from the discharge pipe 12 provided on the side wall of the compression container 11 to the outside of the compressor. You.

In this compressor, an electric motor 13 is built in the pressure vessel 11, and the crankshaft 7 rotates at a rotation speed according to a voltage controlled by an inverter (not shown) outside the compressor, thereby performing a compression operation. Do. An oil reservoir is provided at a lower portion of the motor 13, and the oil passes through an oil hole 14 provided in the crankshaft, and slides between the orbiting scroll member 2 and the crankshaft 7, a sliding bearing 16 and the like. Provided for lubrication.

Next, the refrigeration cycle will be described. FIG. 2 shows a configuration diagram of a heat pump refrigeration cycle such as a room air conditioner or a package air conditioner that also serves as cooling and heating.

When cooling the room, the high-temperature and high-pressure refrigerated gas adiabatically compressed from the discharge pipe of the compressor 18 passes through the four-way valve 19 and is cooled by the outdoor heat exchanger 20 (used as a condensing means). , Becomes a high-pressure liquid refrigerant. This refrigerant is adiabatically expanded by expansion means 21 (for example, a capillary tube or a temperature-type expansion valve) and becomes a low-temperature low-pressure liquid containing a slight amount of gas to the indoor heat exchanger 22 (used as evaporating means). Then, heat is obtained from the air in the room, and the refrigerant reaches the compressor 18 again through the four-way valve 19 in the state of a low-temperature gas. When heating the room, the flow of the refrigerant is changed in the opposite direction by the four-way valve 19, and the operation is reversed.

In this scroll type compressor, a refrigerating machine oil having excellent wear resistance is required because the friction conditions of the slide bearing are severe.

An object of the present invention is to provide a working medium for a refrigerating apparatus having excellent wear resistance and a refrigerating apparatus using the medium.

[0014]

In order to solve the above-mentioned problems, the present invention provides a working medium for a refrigeration system comprising a fluorinated hydrocarbon-based refrigerant and a refrigerating machine oil represented by the following general formula. Provided is a working medium for a refrigerating apparatus, which contains a perfluoroalkylcarboxylic acid glyceride.

[0015]

Embedded image

(Wherein, R ₁ , R ₂ , and R ₃ each independently represent a perfluoroalkylcarboxylic acid residue having 4 to 12 carbon atoms or hydrogen. However, R ₁ , R ₂ , and R ₃ are the same. Although they may be different from each other, they do not become hydrogen at the same time.) 1,1,1,2-Tetrafluoroethane (CF) is used as a fluorinated hydrocarbon-based refrigerant which is a constituent component of the working medium for the refrigeration system. ₃ · CH ₂ F; HFC134a), difluoromethane (C
H ₂ F ₂ ; HFC32), pentafluoroethane (CF _3.
CHF ₂ ; HFC125), 1,1,2,2-tetrafluoroethane (CHF ₂ · CHF ₂ ; HFC134), 1,1,1-trifluoroethane (CF ₃ · CH ₃ ; HFC143a), or Examples thereof include R407C, RA410A, and R410B in which a plurality of these fluorinated hydrocarbon-based refrigerants are mixed. Among them, in the case of R410A used as a substitute refrigerant for the HCFC22, when used in the same environment, the discharge pressure of the compressor reaches about 1.6 times that of the HCFC22, and the sliding conditions of the compressor become severe.

The refrigerating machine oil includes polyol ester, polyether, polycarbonate, naphthenic mineral oil, paraffinic mineral oil, alkylbenzene and the like. Among them, the most typical polyol ester will be described.
The polyol ester includes a polyol ester synthesized from a polyhydric alcohol and a monovalent fatty acid, or a complex type synthesized from a polyhydric alcohol and a divalent fatty acid, or a mixed divalent and monovalent fatty acid. For example, polyhydric alcohols include neopentyl glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol. Monovalent fatty acids are pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid,
-Ethylhexanoic acid, isooctanoic acid, 3,5,5-trimethylhexanoic acid and the like, and these alone or a plurality of kinds of mixed fatty acids are used. The divalent fatty acids include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like.

The perfluoroalkylcarboxylic acid glyceride as a lubricity improver is obtained from glycerin and a perfluoroalkylcarboxylic acid or a carboxylic acid derivative thereof. The obtained perfluoroalkylcarboxylic acid glyceride is shown below. Perfluorobutanoic acid monoglyceride, perfluorobutanoic acid diglyceride, perfluorobutanoic acid triglyceride, perfluoropentanoic acid monoglyceride, perfluoropentanoic acid diglyceride, perfluoropentanoic acid triglyceride, perfluorohexanoic acid monoglyceride, perfluorohexanoic acid diglyceride, perfluoro Hexanoic acid triglyceride, perfluoroheptanoic acid monoglyceride, perfluoroheptanoic acid diglyceride,
Perfluoroheptanoic triglyceride, Perfluorooctanoic monoglyceride, Perfluorooctanoic diglyceride, Perfluorooctanoic triglyceride, Perfluorononanoic monoglyceride, Perfluorononanoic diglyceride, Perfluorononanoic triglyceride, Perfluorodecanoic monoglyceride, Perfluoro There are diglyceride decanoate, triglyceride perfluorodecanoate, monoglyceride perfluoroundecanoate, diglyceride perfluoroundecanoate, triglyceride perfluoroundecanoate, monoglyceride perfluorododecanoate, diglyceride perfluorododecanoate, triglyceride perfluorododecanoate, and the like. It may be a mixture. The mixing ratio of the perfluoroalkylcarboxylic acid glyceride as the lubricity improver is 0.01% by weight to 5.0% by weight with respect to the above-mentioned refrigerating machine oil, and is 0.1 to 1.0% by weight.
It is more preferable to mix at 0% by weight. The mixing ratio of the amine salt of perfluoroalkyl carboxylic acid is set at 0.1.
This is because abrasion resistance cannot be sufficiently obtained with a mixing ratio of 01% by weight or less. On the other hand, when the blending ratio of perfluoroalkylcarboxylic acid glyceride is 5.0% by weight or more, it does not completely dissolve in the refrigerating machine oil, and causes a clogging phenomenon of a dryer or a capillary tube.

It is to be noted that an antioxidant, an acid scavenger, an antifoaming agent, a metal deactivator and the like may be added to the working medium for the refrigerating device within a range not to impair the object of the present invention.

By adding perfluoroalkyl carboxylic acid glyceride to the refrigerating machine oil, a strong adsorption film is formed on the sliding surface to prevent metal-to-metal contact, reduce the coefficient of friction, and dramatically improve wear resistance. To improve.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments. Example 1 shows a method for synthesizing a representative fluorinated glyceride derivative.

Example 1 50 purged with dry nitrogen
In a 0 ml three-necked flask, 2.2 g (0.024 mol) of sufficiently dehydrated glycerin and 1 ml of 1N hydrochloric acid are dissolved in 19.8 g of dimethylformamide, and sufficiently stirred.
5 g of perfluorooctanoic acid (0.012 mol
45 g of dimethylformamide in which l) was dissolved was slowly added dropwise, and the mixture was stirred at room temperature for 10 hours while flowing dry nitrogen to obtain a solution (1). Next, pyridine in the same mole as hydrochloric acid is added to the solution (1), and the mixture is further stirred at room temperature for 1 hour. After the reaction, the solution (1) is transferred to a separating funnel for 500 ml, and extracted three times with 100 ml of trichlorotrifluoroethane. The lower layer is separated to obtain solution (2). An appropriate amount of anhydrous sodium sulfate is added to remove water from the solution (2), and the mixture is stirred well and filtered. Next, the solvent is removed from the solution (2) by an evaporator to obtain 5 g of a mixture of white and solid perfluorooctanoic acid monoglyceride and perfluorooctanoic acid diglyceride. The structure of the synthesized compound was confirmed by an infrared absorption spectrometer.
FIG. 3 shows an infrared absorption spectrum of compound B synthesized with perfluorooctanoic acid A as a raw material. Since the synthesized compound showed absorption of an ester not present in the raw material perfluorooctanoic acid at around 1740 cm- ^1, it was confirmed that glycerin was esterified with perfluorooctanoic acid.

Examples 2 to 10 The following were used as fluorohydrocarbon-based refrigerant (HFC), refrigerating machine oil, and perfluoroalkylcarboxylic acid glyceride as a lubricity improver.

A fluorohydrocarbon refrigerant HFC134a was used.

Refrigerator oil A carboxylic acid ester of pentaerythritol was used. The viscosity grade is VG32.

Lubricity improver A: Perfluorobutanoic acid glyceride B: Perfluoropentanoic acid glyceride C: Perfluorohexanoic acid glyceride D: Perfluoroheptanoic acid glyceride E: Perfluorooctanoic acid glyceride F: Perfluorononanoic acid diglyceride G : Diglyceride perfluorodecanoic acid H: diglyceride perfluoroundecanoic acid I: diglyceride perfluorododecanoic acid 0.5% by weight of these lubricity improvers based on refrigerator oil.
The abrasion resistance of the added refrigerating machine oil was evaluated by the following method using a Falex tester. About 6mm in diameter
The rotating shaft (pin) is sandwiched between two V blocks symmetrically from left and right, and immersed in refrigerator oil filled in an oil cup. HFC134a is blown into the oil at a flow rate of 150 ml / min for 10 minutes to saturate the oil. Continue blowing during the test. Next, load 250lb, oil temperature 100 ° C, rotation speed 2
It was operated at 90 rpm for 5 hours, and the value obtained by calculating the total wear depth of the pin and the V block from the change in the scale of the ratchet, which is the load mechanism of the Falex tester, with the load corrected was taken as the amount of wear. The warm-up operation was performed at 50 lb for about 10 minutes while the temperature was raised from room temperature to 100 ° C.

[Comparative Examples 1-4] The following were used as a fluorinated hydrocarbon-based refrigerant (HFC), refrigerating machine oil, and a lubricity improver.

The fluorocarbon refrigerant HFC134a was used.

Refrigerator oil A carboxylic acid ester of pentaerythritol was used. The viscosity grade is VG32.

Lubricity improver J: tricresyl phosphate K: dilauryl hydrogen phosphite L: oleyl alcohol Evaluation was performed under the same conditions as in Examples 2 to 10.

Table 1 shows the results of the Falex test conducted on the polyol ester. As is evident from Table 1, the working medium for the refrigerating apparatus of the present invention has less abrasion and excellent abrasion resistance as compared with the base oil alone and the lubricity improver used in the comparative example.
At the same time, the coefficient of friction has been reduced.

[0032]

[Table 1]

[Examples 11 to 18] [Comparative Examples 5 to 11] Next, in Examples 2 to 10, a lubricity improver was used using a perfluoroalkyl carboxylic acid glyceride which was confirmed to improve abrasion resistance. Using a Falex tester, changing the amount of
The abrasion resistance was evaluated.

A fluorinated hydrocarbon refrigerant HFC134a was used.

Refrigerator oil Trimethylolpropane carboxylate (viscosity grade VG56) Polyether (viscosity grade VG68) Polycarbonate (viscosity grade VG68) Naphthenic mineral oil (viscosity grade VG56) Alkylbenzene (viscosity grade VG56) Abrasion resistance of the refrigerating machine oil in which the lubricity improver was blended at a predetermined ratio with each refrigerating machine oil was evaluated under the following test conditions. HFC134a flow rate 150ml / min, load 100l
b, the oil temperature was 120 ° C., the rotation speed was 290 rpm, the running time was 5 hours, and the running-in operation was 50 lb for about 10 minutes. The amount of wear was determined by the same method as in Example 1.

Table 2 shows the results of Examples and Comparative Examples.

[0037]

[Table 2]

As is evident from Table 2, the working medium for a refrigeration system of the present invention has a smaller amount of abrasion and is superior in abrasion resistance as compared with the comparative example using the base oil alone regardless of the type of the base oil. In addition, as shown in Comparative Example 6, when the perfluoroalkylcarboxylic acid glyceride was added in an amount of 0.01% by weight or less to the refrigerating machine oil, sufficient abrasion resistance was not obtained.
In addition, as shown in Comparative Example 7, a test in which 10% by weight of perfluoroalkylcarboxylic acid glyceride was added was not completely dissolved in refrigerator oil, so that the test could not be performed.

[Example 19] [Comparative examples 12 to 14] Next, in Examples 2 to 10 described above, a perfluoroalkylcarboxylic acid glyceride E, which was confirmed to improve abrasion resistance, was used. evaluated. For comparison, base oil alone and K as a lubricity improver were used.

A fluorocarbon refrigerant R407C was used.

Refrigerator oil A carboxylic acid ester of pentaerythritol was used. The viscosity grade is VG68.

The above-mentioned fluorohydrocarbon-based refrigerant and refrigerating machine oil were sealed in a glass ampule tube at a weight ratio of 1: 1 and a shield tube test was performed. The lubricity improver was added in an amount of 0.5% by weight to the refrigerating machine oil. Copper, iron, and aluminum coexist in the catalyst, and after heating at 175 ° C for 21 days, 1 oil is added.
The total acid value was determined by titration with an aqueous solution of / 10 N-KOH (in propanol).

Table 3 shows the evaluation results of the thermal stability.

[0044]

[Table 3]

As is clear from Table 3, the working medium for a refrigeration system of the present invention has a small increase in total acid value and is excellent in heat stability compared with the base oil alone and the lubricity improver of Comparative Example 12. . Also, no discoloration of the catalyst was observed.

Next, the compatibility between the fluorohydrocarbon-based refrigerant and the refrigerating machine oil containing the lubricity improver was evaluated. For comparison, a refrigerating machine oil alone and a lubricity improver L were used.

The fluorocarbon refrigerant HFC134a was used.

Refrigerator oil A carboxylic acid ester of pentaerythritol was used. The viscosity grade is VG32.

The compatibility between the above-mentioned fluorohydrocarbon-based refrigerant and the refrigerating machine oil was evaluated according to JIS K2211.

Table 3 shows the evaluation results of the compatibility. As is clear from Table 3, the working medium for a refrigerating apparatus of the present invention does not impair the compatibility between the fluorohydrocarbon-based refrigerant and the refrigerating machine oil, and has a higher fluidity than the lubricity improver of Comparative Example 13. Shows excellent solubility in chlorinated hydrocarbon refrigerants and refrigeration oils.

Example 20 A refrigerating machine in which a refrigerating machine oil alone and 0.5% by weight of perfluoroalkylcarboxylic acid glyceride E as a lubricity improver were added to a refrigerating cycle incorporating an actual scroll compressor, and lubrication. Using a refrigerating machine oil to which dilauryl hydrogen phosphite K was added in an amount of 0.5% by weight as a performance improver, each was operated under a predetermined condition and for a predetermined time, and the wear amount of the sliding bearing was compared.

R410A was used as the fluorinated hydrocarbon-based refrigerant, and the refrigerant oil shown in Example 11 was used as the refrigerating machine oil.

The scroll type compressor is a sliding bearing whose lubrication is severe. Therefore, the wear resistance was evaluated by measuring the wear amount of the shaft.

FIG. 4 shows the relationship between the amount of shaft wear and time. The refrigerating machine oil blended with dilauryl hydrogen phosphite K as a lubricity improver has a small initial wear amount, but the wear is greatly increased when the friction time is long. In addition, the total acid value of the oil after the test was high due to poor thermal stability, and deposits were observed on the capillary tube as the expansion means of the refrigeration cycle. On the other hand, refrigeration oil alone, R410A
Has increased the pressing force of the vane due to the high discharge pressure. Therefore, the amount of wear is slightly larger than that of the HCFC22 / mineral oil of the current combination, and the wear cannot be sufficiently suppressed. In contrast, a refrigerating machine oil containing perfluoroalkyl carboxylic acid glyceride E as a lubricity improver is
Compared to the refrigerating machine oil alone, the abrasion was small, the total acid value of the oil after the test was low, and no blockage of the capillary tube, which was the expansion means of the refrigerating cycle, was observed. From the above results,
By adding 0.01% by weight or more of these perfluoroalkylcarboxylic acid glycerides to the refrigerating machine oil, the wear resistance of the working medium for the refrigerating apparatus is remarkably improved regardless of the type of the refrigerating machine oil, and the friction coefficient is increased. Was confirmed to be reduced.

By using the working medium for a refrigerating apparatus of the present invention in a refrigerating apparatus, it was confirmed that the wear of the sliding portion was suppressed, and the refrigerating cycle was not blocked, and the reliability was greatly improved.

In the present invention, the results of the evaluation on the actual machine are described only for the polyol ester which is soluble in the chlorine-free alternative refrigerant. However, for example, an oil for ensuring the oil return from the refrigeration cycle to the compressor is used. Set up a recovery mechanism, or use fluorinated hydrocarbon refrigerants such as prohan, isobutane,
Mineral oil insoluble in hydrocarbon-based refrigerants, for example, by slightly mixing pentane, can be applied to a refrigeration cycle using alkylbenzene. Further, an antioxidant, an acid scavenger, an antifoaming agent, a metal deactivator, and the like may be mixed as long as lubricity and compatibility with the refrigerant are not impaired.

[0057]

The working medium for a refrigerating apparatus of the present invention is a composition comprising a fluorocarbon-based refrigerant and a refrigerating machine oil,
Perfluoroalkylcarboxylic acid glyceride is added to 0.0
By adding 1% by weight or more, the refrigeration cycle is not blocked, wear of the sliding portion of the compressor is suppressed, the friction coefficient is reduced, and a highly reliable refrigeration apparatus is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a scroll compressor.

FIG. 2 is an explanatory diagram of a refrigeration cycle of the refrigeration apparatus.

FIG. 3 is a characteristic diagram of wave number-absorbance.

FIG. 4 is a characteristic diagram of a wear amount.

[Explanation of symbols]

1: fixed scroll member, 2: orbiting scroll member,
3, 4 ... end plate, 5, 6 ... wrap, 7 ... crankshaft, 8 ... compression chamber, 9 ... discharge port, 10 ... frame, 11 ...
Pressure vessel, 12 ... Discharge pipe, 13 ... Motor, 14 ... Oil hole, 15 ... Aldam ring, 16 ... Slide bearing, 17 ...
Suction pipe.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Sasaki 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Mina Ishida 7-1 Omikacho, Hitachi City, Ibaraki Prefecture No. 1 Inside the Hitachi Research Laboratory, Hitachi, Ltd.

Claims (9)

[Claims] 1. A working medium for a refrigerating device comprising a fluorohydrocarbon-based refrigerant and a refrigerating machine oil, wherein a perfluoroalkylcarboxylic acid monoglyceride or perfluoroalkylcarboxylic acid synthesized from glycerin and a perfluoroalkylcarboxylic acid. A working medium for a refrigerating device, comprising a diglyceride, a perfluoroalkylcarboxylic acid triglyceride, or a mixture thereof. 2. The perfluoroalkyl carboxylic acid glyceride according to claim 1, wherein the perfluoroalkyl carboxylic acid monoglyceride, perfluoroalkyl carboxylic acid diglyceride, perfluoroalkyl carboxylic acid triglyceride or a mixture thereof is represented by the following general formula: Working medium for refrigeration equipment. Embedded image (In the formula, R ₁ , R ₂ , and R ₃ each independently represent a perfluoroalkylcarboxylic acid residue having 4 to 12 carbon atoms or hydrogen. However, even if R ₁ , R ₂ , and R ₃ are the same, It may be different, but will not be hydrogen at the same time.) 3. A working medium for a refrigerating apparatus, wherein the perfluoroalkylcarboxylic acid glyceride according to claim 2 is contained in an amount of 0.01% by weight to 5.0% by weight based on a refrigerating machine oil. 4. A working medium for a refrigerating device, wherein the perfluoroalkylcarboxylic acid glyceride according to claim 2 is perfluorooctanoic acid glyceride. 5. A working medium for a refrigeration system containing the perfluorooctanoic acid according to claim 4 in an amount of 0.01% by weight to 5.0% by weight relative to the refrigeration oil. 6. A refrigeration system having a refrigeration cycle comprising a compression means, a condensation means, an expansion means, and an evaporation means, wherein a fluorinated hydrocarbon-based refrigerant, a refrigerating machine oil, A refrigeration apparatus containing a perfluoroalkylcarboxylic acid glyceride represented by the general formula: Embedded image (In the formula, R ₁ , R ₂ , and R ₃ each independently represent a perfluoroalkylcarboxylic acid residue having 4 to 12 carbon atoms or hydrogen. However, even if R ₁ , R ₂ , and R ₃ are the same, It may be different, but will not be hydrogen at the same time.) 7. A refrigerating apparatus containing the perfluoroalkylcarboxylic acid glyceride according to claim 6 in an amount of 0.01% by weight to 5.0% by weight based on the amount of the refrigerating machine oil. 8. A working medium for a refrigerating device, wherein the perfluoroalkyl carboxylic acid glyceride according to claim 6 is perfluorooctanoic acid glyceride. 9. A refrigerating apparatus containing the perfluorooctanoic acid according to claim 8 in an amount of 0.01% by weight to 5.0% by weight relative to the refrigerating machine oil.