JPH06248286A - Refrigerator - Google Patents

Abstract

PURPOSE:To improve performance and reliability of a refrigerator by using R134. CONSTITUTION:A refrigerator has a fluorinated hydrocarbon not containing chlorine and a refrigerator oil 18 sealed in a refrigerating cycle A. The refrigerator oil 18 uses a mixed oil obtained by adding 10-50% of a polyol ester-based oil composed of a polyhydric alcohol and a fatty acid to at least one base oil selected from a group consisting of an alkylbenzene oil and a mineral oil. The polyol ester-based oil is obtained from a raw material prepared by polymerizing a tri or polyhydric polyol such as trimethylolpropane or pentaerythritol with a straight-chain or side-chain alkyl-based fatty acid in the absence of a catalyst and has <=-40 deg.C pour point, <=-20 deg.C two liquid separating point, <=0.02 mg KOH/g total acid value, 8-100 cst viscosity at 40 deg.C and >=80 viscosity index.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is applicable to refrigerants of 1, 1, 1, 2
Refrigeration using a fluorohydrocarbon-based refrigerant that does not contain chlorine, such as tetrafluoroethane (hereinafter referred to as R134a), and refrigeration that uses a refrigerating machine oil in which a mineral oil or alkylbenzene oil is mixed with a polyol ester oil as a base oil Regarding the device.

[0002]

2. Description of the Related Art Refrigerators, vending machines, and compressors for showcases have conventionally used a large amount of dichlorodifluoromethane (hereinafter referred to as R12) as a refrigerant. This R12
Is subject to CFC regulations due to the problem of ozone layer depletion. Then, as an alternative refrigerant of this R12, R134a
Fluorohydrocarbon-based refrigerants containing no chlorine (HF)
C, FC) are being considered for refrigerators (for example,
See Japanese Patent Application Laid-Open No. 1-271491).

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
134a has poor compatibility with refrigerating machine oils such as currently used mineral oils and alkylbenzene oils, leading to deterioration of oil return to the compressor, sucking of separated refrigerant at the time of start-up, and poor lubrication of the compressor. There was a problem.

Therefore, the present inventors have examined a polyol ester oil as a refrigerating machine oil compatible with the refrigerant R134a. However, when this polyol ester oil is used in a refrigerant compressor, particularly a rotary compressor, it causes corrosion of the sliding member by the fatty acid generated by decomposition by heat,
It was found to cause wear.

Then, the present inventors used R134 as a refrigerant.
As a result of repeated research to use a in combination with a polyol ester-based oil as a refrigerating machine oil in a refrigerant compressor, the polyol ester-based oil undergoes hydrolysis due to the influence of moisture to cause total acid Price increases, metal soap is produced and becomes sludge, which adversely affects the refrigeration cycle, and due to the influence of oxygen and chlorine, decomposition, oxidative deterioration, and polymerization reactions occur, and metal soap and polymer sludge are produced and frozen. It was found that the cycle was adversely affected.

On the other hand, the present inventors have used R134a as a refrigerant.
It has been found that, when the above is used, the refrigerating machine oil can be returned to the compressor in the refrigeration cycle by adding a special polyol ester oil to the mineral oil or the alkylbenzene oil as the refrigerating machine oil.

Therefore, the present inventors have added a special polyol ester oil to a mineral oil or an alkylbenzene oil, used a specific raw material for the polyol ester oil, and used it in a specific physical range, or added a special additive. It has been found that the above problems can be solved by adding the same, maintaining the purity of the fluorohydrocarbon refrigerant at a high value, and suppressing the equilibrium water content of the refrigeration cycle.

An object of the present invention is to obtain a good refrigeration system by solving the above problems.

[0009]

According to a first aspect of the present invention, there is provided a refrigeration system in which a chlorine-free fluorohydrocarbon-based refrigerant and a refrigerating machine oil are enclosed in a refrigerating cycle. , Alkylbenzene oil or at least one base oil selected from the group consisting of mineral oils and 10 to 10 of a polyol ester oil composed of a polyhydric alcohol and a fatty acid.
A mixed oil containing 50% (hereinafter referred to as a mixed oil) is used, and the polyol ester oil is a trivalent or higher polyol such as trimethylolpropane or pentaerythritol, and a linear or side chain alkyl-based oil. Raw material obtained by polymerizing fatty acid without catalyst, pour point is −40 ° C. or lower, two-liquid separation temperature is −20 ° C. or lower, and total acid value is 0.02 mgK0H / g
In the following, the viscosity is 40 to 100 ° C. and the viscosity index is 80 or more.

According to a second aspect of the present invention, there is provided a refrigerating apparatus using a mixed oil in a refrigeration cycle using a fluorohydrocarbon-based refrigerant containing no chlorine, wherein the fluorohydrocarbon-based refrigerant is
Purity is 99.95 wt% or more and chlorine-based refrigerant is mixed in 8
The refrigeration apparatus according to claim 1 having a content of 0 ppm or less.

Further, as set forth in claim 3, the equilibrium water content (shown by the following formula I) in the refrigeration cycle is 200 ppm or less in the initial state of operation. Further, as described in claim 4, the residual oxygen amount in the refrigeration cycle is set to 0.01 vol% or less of the internal volume of the refrigeration cycle.

Further, as described in claim 5, the mixed oil contains
As an additive, a phenolic antioxidant such as 2,6 ditertiarybutyl paracresol (DBPC) is 0.1 to 0.1%.
The refrigeration apparatus according to claim 1, wherein 0.5 wt% is added.

According to the sixth aspect, the mixed oil contains
The refrigeration system according to claim 1, wherein a copper deactivator such as benzotriazole (BTA) of 20 ppm or less is added.

Further, as described in claim 7, in the mixed oil,
2 wt% or less tricresyl phosphate (TCP)
The refrigerating apparatus according to claim 1, wherein an extreme pressure additive such as is added.

Further, as described in claim 8, the mixed oil comprises:
The refrigeration apparatus according to claim 1, wherein 0.1 to 0.5 wt% of an epoxy additive is added.

[0016]

The present invention is constructed as described above,
The following effects are achieved.

According to the structure of claim 1, the polyol ester oil in the mixed oil of the present invention has good compatibility with the fluorohydrocarbon type refrigerant in the entire temperature range used in the refrigerating apparatus, and the refrigerant and the oil are Bilayer separation can be eliminated.

Therefore, the polyol ester oil always exists in a state of being dissolved in the fluorohydrocarbon refrigerant (for example, 134a) in the low temperature region of -30 ° C. or lower in the refrigeration cycle, and the viscosity becomes low as a whole, so that the compression is performed. Good oil return to the machine.

On the other hand, since the mixed oil uses mineral oil or alkylbenzene oil as the base oil, the harmful effect of the polyol ester oil, that is, hydrolysis due to frictional heat of the sliding portion of the compressor can be reduced as much as possible, and the metal Sludge can be almost eliminated by suppressing the generation of soap. Therefore, the oil level of the compressor is not lowered, it is possible to secure oil supply to the bearing sliding portion, and prevent biting and seizure.

Moreover, in the polyol ester oil in the mixed oil of the present invention, the ester bond possessed by the oil itself is mainly molecularly oriented to the surface of the iron-based sliding portion of the shaft and the bearing of the compressor to enhance lubricity. And the action of easily dissolving in the refrigerant (134a), the actual viscosity can be reduced, the mechanical loss can be reduced, and the coefficient of performance of the compressor can be improved.

Further, according to the second aspect of the present invention, since the purity of the fluorohydrocarbon type refrigerant is extremely high, chlorine is decomposed into the polyol ester oil with almost no inclusion of foreign matter or CFC in the refrigeration cycle. Then, it becomes a fatty acid, and it is possible to suppress the reaction with a metal to generate a metal soap, to reduce the precipitation of sludge, to ensure the compatibility between the polyol ester oil and the refrigerant, and to obtain stable performance.

According to the third aspect of the present invention, it is possible to prevent the oil from being hydrolyzed at the initial stage of operation of the refrigerating apparatus, to reduce the total oxidation and to suppress the generation of sludge due to the formation of metal soap. Lubrication characteristics can be secured in the sliding parts.

According to the fourth aspect of the present invention, it is possible to prevent the oxidative deterioration of the polyol ester oil and the sludge due to the polymerization, and it is possible to provide a refrigerating apparatus having excellent reliability.

According to the fifth aspect of the invention, this polyol ester oil can improve the stability against oxidative deterioration as compared with glycol oil and the like, and can improve the performance and reliability of the compressor.

Further, according to the structure of claim 6, it is possible to adsorb on the copper surface which becomes the sliding surface of the bearing, suppress its catalytic action, and suppress hydrolysis.

Further, according to the structure of claim 7, a strong chemical adsorption film can be formed on the bearing sliding surface, the lubricity of the sliding portion can be improved, and biting and seizure can be prevented.

Further, according to the structure of claim 8, hydrolysis can be suppressed, the total acid value can be reduced to suppress the generation of metal soap, and the reliability of the apparatus can be improved.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a vertical sectional view of the rotary compressor. In FIG. 1, A is a refrigerating cycle which constitutes a refrigerating apparatus, and is constituted by connecting a compressor B, a condenser C, a pressure reducing device D, an evaporator E, and a drier F by piping. And the compressor B
Has the following structure:

Reference numeral 1 denotes a closed container in which an electric element 2 is housed on the upper side and a rotary compression element 3 driven by the electric element is housed on the lower side. The electric element 2 is composed of a stator 5 having a winding 4 insulated with an organic material, and a rotor 6 provided inside the stator. The rotary compression element 3 includes a cylinder 7 and a roller 10 that rotates along an inner wall of the cylinder 7 by an eccentric portion 9 of a rotary shaft 8.
And a vane 12 pressed by a spring 11 so as to be pressed against the peripheral surface of the roller to partition the inside of the cylinder 7 into a suction side and a discharge side, and an opening of the cylinder 7 is sealed, and a rotary shaft 8 is pivotally supported. It is composed of an upper bearing 13 and a lower bearing 14.

Further, the upper bearing 13 is provided with a discharge hole 15 which communicates with the discharge side of the cylinder 7. Further, a discharge valve 16 that opens and closes the discharge hole 15 and a discharge muffler 17 that covers the discharge valve are attached to the upper bearing 13.

The rollers 10 and the vanes 12 are made of an iron material.

The bottom of the closed container 1 has poor compatibility with the R134a refrigerant, but is excellent in abrasion resistance, oxidation stability, electrical insulation, etc., and has a kinematic viscosity of 36.2 cst at 40 ° C. A naphthene-based mineral oil or an alkylbenzene oil is compatible with the R134a refrigerant described later, and a polyol ester-based oil composed of a polyhydric alcohol and a fatty acid having a kinematic viscosity of 30.7 cst at 40 ° C. (detailed later). The mixed oil 18 containing is stored as refrigerating machine oil.

The mixed oil 18 contains 10 to 50% by weight of a polyol ester oil. And, the polyol ester oil is preferably contained in an amount of 20% by weight.

Generally, the refrigerating machine oil discharged from the closed container 1 to the condenser C side together with the refrigerant discharged from the discharge pipe 20 of the rotary compressor B in a high temperature region where the refrigerant pressure is high. Although the refrigerant flows through the refrigeration cycle A, in the low temperature region where the refrigerant pressure is low, the oil viscosity increases and the fluidity is lost, and the refrigeration cycle A tends to be stagnant. That is, the refrigerating machine oil is likely to remain in the evaporator E. Refrigerating machine oil such as paraffin-based or naphthene-based mineral oil or alkylbenzene oil, which has a poor compatibility with the refrigerant, does not lower the freezing point of the refrigerating machine oil due to the refrigerant.
Oil viscosity becomes high inside and fluidity is impaired. In order to solve this, in this embodiment, as described above, R134 is added to the base oil such as mineral oil or alkylbenzene oil.
There are 10 polyol ester oils that are compatible with the refrigerant of a.
˜50% by weight. And this mixed oil 18
The R134a refrigerant that dissolves in the polyol ester-based oil lowers the freezing point temperature, suppresses an increase in viscosity, and prevents the fluidity in the evaporator E from being impaired.

By limiting the content of the polyol ester oil contained in the mineral oil or the alkylbenzene oil to 10 to 50% by weight, the chemical stability of the mixed oil 18 is not impaired.

This was confirmed by the following experiment.
That is, the return state of the mixed oil 18 was confirmed with a refrigeration cycle tester as shown in FIG. 3, and the total acid number of the refrigerating machine oil was evaluated using iron and copper as catalysts in the air atmosphere, and the result was displayed. Shown in 1.

[0038]

[Table 1]

Reference numeral 25 is a rotary compressor corresponding to the rotary compressor B, 26 is a heat exchanger corresponding to the condenser C, 27 is a pressure reducing device corresponding to the pressure reducing device (capillary tube) D, 28
Is a heat exchanger corresponding to the evaporator E, and these are connected by piping. A sight glass 29 for confirming the amount of refrigerating machine oil is attached to the rotary compressor 25. The test conditions were as follows: the capacity of the rotary compressor 25 was 175 W, the condensing temperature of the heat exchanger 26 was 40 ° C., the evaporation temperature of the heat exchanger 28 was −25 ° C., the refrigerant used was R134a, and alkylbenzene oil and polyol ester oil were used. The oil return property of the mixed oil 18 was confirmed when the mixing ratio was changed.

A mixed oil 1 in which the mixing ratio of the alkylbenzene oil and the polyol ester oil in the air atmosphere is changed
The catalyst of iron and copper was put in 8, heated at 90 ° C., and the total acid value after 30 days was measured.

As a result, it can be seen from Table 1 that the oil-returning property and the heat stability of the mixed oil 18 are good when the alkylbenzene oil contains 10 to 50% by weight of the polyol ester oil. By using less oil than the alkylbenzene oil, the rotary compressor 25
It is considered that the hydrolysis of the polyol ester-based oil due to the frictional heat at the sliding portion is suppressed. Further, the higher the mixing ratio of the polyol ester-based oil is, the better the oil return property of the mixed oil 18 is that the polyol ester-based oil has R
It is considered that the refrigerant of 134a is melted and the freezing point temperature of the mixed oil 18 is lowered, and the decrease in the viscosity of the mixed oil 18 in the evaporator 28 is suppressed.

That is, if the content of the polyol ester oil exceeds 50%, friction heat of the sliding portion of the rotary compressor 25 causes the polyol ester oil to hydrolyze, and the sliding portion causes fatty acid corrosion. There is danger.

The polyol ester-based oil mixed with the mixed oil 18 will be described in detail below. The polyol-based oil does not include trihydric or higher-valent polyols such as trimethylolpropane and pentaerythritol, and linear or side chain alkyl fatty acids. It is composed of a raw material polymerized with a catalyst, has a pour point of -50 ° C, a two-liquid separation temperature of -30 ° C, a total acid value of 0.01 mgKOH / g or less, a viscosity of 32 cst at 40 ° C, and a viscosity index of 95. use.

To the polyol ester oil, 0.3 wt% of a phenolic antioxidant of 2,6 ditertiarybutyl paracresol (DBPC) was added as an additive for the purpose of preventing oxidative deterioration under long-term storage. And again
An epoxy additive of 0.25 wt% is added for the purpose of preventing hydrolysis.

If necessary, 5 ppm of a copper deactivator of benzotriazole (BTA) and 1 wt% of a tricresyl phosphate (TCP) extreme pressure additive were added to the polyol ester oil. It

The refrigeration cycle A is filled with a chlorine-free fluorohydrocarbon type refrigerant, for example, R134a.

R134a has a purity of 99.97 wt%.
Then, the mixing amount of the chlorine-based refrigerant is adjusted to 56 ppm. Further, the equilibrium water content (shown by the following formula I) in the refrigeration cycle A is adjusted to be 150 ppm in the initial state of operation. The dryer F used in the refrigeration cycle A has a water adsorbent having a pore diameter of about 3Å. Further, the residual oxygen amount in the refrigeration cycle A is adjusted to 0.005 vol% of the cycle internal volume.

In the electric element 2 of the compressor B, the winding 4 has a two-layer structure in which a layer made of heat resistant ester (THEIC) or ester imide is applied on the inside and a layer made of amido imide is applied on the outside. Is coated with the insulating material of No. 3, and a PET film having a low oligomer specification (0.6 wt% or less as trimer) is used as the insulating paper H that insulates between the windings 4 and the like.

The oil 18 lubricates the sliding surface between the vane 12 and the roller 10 which is the sliding member of the rotary compression element 3.

The refrigerant that flows into the cylinder 7 of the rotary compression element 3 and is compressed by the cooperation of the roller 10 and the vane 12 is R compatible with the polyol ester oil in the mixed oil 18.
It is formed of 134a.

Reference numeral 19 is a suction pipe attached to the closed container 1 to guide the refrigerant to the suction side of the cylinder 7. Reference numeral 20 is attached to the upper wall of the closed container 1 and is compressed by the rotary compression element 3 via the electric element 2. A discharge pipe for discharging the refrigerant to the outside of the closed container 1.

In the refrigerating machine oil composition used in the rotary compressor thus constructed, the refrigerant R134a flowing from the suction pipe 19 to the suction side in the cylinder 7 is the roller 10
Is compressed by the cooperation of the vane 12 with the vane 12 and is discharged through the discharge hole 15 into the discharge muffler 17 by opening the discharge valve 16.
The refrigerant in the discharge muffler passes through the electric element 2 and the discharge pipe 2
It is discharged from 0 to the outside of the closed container 1. And oil 18
Is supplied to the sliding surfaces of sliding members such as the rollers 10 and the vanes 12 of the rotary compression element 3 to perform lubrication. Further, the refrigerant compressed in the cylinder 7 is prevented from leaking to the low pressure side.

According to the present embodiment, the above-described structure has the following effects.

According to the constitution of claim 1, the mixed oil 1 of the present invention
No. 8 has a good compatibility with R134a in the entire temperature range used in the refrigerating machine A due to the polyol ester type oil,
It is possible to eliminate the two-layer separation of the refrigerant and the oil.

Therefore, the polyol ester oil always exists in the state of being dissolved in 134a in the low temperature region of -30 ° C. or lower in the refrigeration cycle A, and the viscosity becomes low as a whole.
The oil return to the compressor B becomes good. Therefore, the oil level of the compressor B is not lowered, and it is possible to secure oil supply to the bearing sliding portions 8, 13, 14 and prevent biting and seizure.

Moreover, in the mixed oil 18 of the present invention, the ester bond possessed by the polyol ester oil itself is molecularly oriented mainly on the surfaces of the shaft 8 of the compressor B and the iron-based sliding parts of the bearings 13 and 14 to lubricate them. Due to the action of improving the property and the action of easily dissolving in the refrigerant (134a), the actual viscosity can be lowered, the mechanical loss can be reduced, and the coefficient of performance of the compressor B can be improved.

According to the second aspect of the present invention, the refrigeration cycle A has a very high purity of the refrigerant 134a.
Almost no foreign matter or CFC mixed in, and mixed oil 18
It is possible to secure compatibility with the refrigerant and obtain stable performance.

Further, according to the third aspect of the invention, it is possible to prevent the oil from being hydrolyzed at the initial stage of operation of the refrigerating apparatus, reduce the total oxidation and suppress the generation of sludge due to the formation of metal soap. Lubrication characteristics can be secured in the sliding parts.

According to the structure of claim 4, the mixed oil 18
It is possible to prevent oxidative deterioration of the inside polyol ester oil and sludge due to polymerization, and to provide a refrigerating apparatus having excellent reliability.

According to the structure of claim 5, the mixed oil 18
The polyol ester oil in the inside can improve the stability against oxidative deterioration as compared with glycol oil and the like, and can improve the performance and reliability of the compressor B.

This was also confirmed from the experimental result by the shield tube test in which the polyol ester type oil in the mixed oil 18 of the present invention to which DBPC was added was enclosed.

That is, according to the polyol ester-based oil 18 of the present invention to which DBPC was added under the condition that the water content was adjusted to 200 ppm by aging at 90 ° C. for 29 days, the total acid value was 0.01 at the initial stage. Below,
Good results have been obtained.

Further, according to the structure of claim 6, it can be adsorbed on the copper surface to be the bearing sliding surfaces 8, 10, 13, 14 and its catalytic action can be suppressed, and hydrolysis can be suppressed.

Further, according to the structure of claim 7, a strong chemical adsorption film can be formed on the bearing sliding surfaces 8, 10, 13, 14 and the sliding parts 8, 10, 13, 14 are lubricated. Better and can prevent chewing and seizure.

Further, according to the constitution of claim 8, hydrolysis can be suppressed, the total acid value can be reduced to suppress the generation of metal soap, and the reliability of the apparatus can be improved.

The above-mentioned effects were confirmed from the result of the durability test by the actual machine shown in FIG.

That is, in the graph of FIG. 2 in which the horizontal axis shows the time of the durability test and the vertical axis shows the amount of contamination (sludge amount), the mixed oil 18 of the present invention to which an additive (DBPC, epoxy, etc.) was added Sample V according to the standard B (the purity of the refrigerant, the amount of water, chlorine, and oxygen in the refrigeration cycle A is limited) using the sample Z of No. 1 as the production standard of the apparatus is the best result. Indicated.

It was also confirmed that the mixed oil 18 of the present invention has a smaller amount of contamination than the conventional mixed oil of the polyol ester type even when no additive is added.

The contents of Samples I to IV in FIG. 2 are as follows.

[0070]

[Table 2]

However, additive X: DBPC + BTA, however, additive Y: DBPC + BTA + TCP additive Z: DBPC + BTA + TCP + epoxy Production standard A: (conventional standard) Refrigerant purity: 99.90 wt% Equilibrium water content in refrigeration cycle A: 600 ppm Residual oxygen content in refrigeration cycle A: 0.03 vol% Remaining chlorine content in refrigeration cycle A: 400 ppm Production standard B: (standard of the present invention) Refrigerant purity: 99.95 wt% Equilibrium water content in refrigeration cycle A: 200 ppm Residual oxygen amount in the refrigeration cycle A: 0.01 vol% Chlorine residual amount in the refrigeration cycle A: 100 ppm In the present embodiment, R134a was described as an example of a fluorohydrocarbon refrigerant containing no chlorine. However, the polyol ester of the present invention can be applied to other HFC refrigerants. The system oil exhibits excellent compatibility and can be applied to these refrigerants.

[0072]

As described above, according to the present invention, since the refrigerating machine oil is the mixed oil and the mineral oil or the alkylbenzene oil is the base oil, the harmful effect of the polyol ester oil, that is, the friction of the sliding portion of the compressor is Hydrolysis due to heat or the like can be reduced as much as possible, the generation of metal soap can be suppressed, and sludge can be almost eliminated. Further, by using a specific raw material for the polyol ester oil in the mixed oil, it can be used in a specific physical property range, a special additive can be added, or the purity of the fluorohydrocarbon refrigerant can be maintained at a high value, By suppressing the equilibrium water content of the refrigeration cycle, R134a can be returned to the compressor in a state of being dissolved in the polyol ester oil, and the oil return can be improved, and hydrolysis due to the effect of water content can be achieved. Suppress the total acid number by suppressing the generation of metal soap to prevent the adverse effect on the refrigeration cycle, and suppress the decomposition, oxidative deterioration, and polymerization reaction due to the effect of oxygen and chlorine to suppress the metal soap. It is possible to prevent the formation of polymer sludge and to obtain a good refrigeration system.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a rotary compressor showing an embodiment of the present invention.

FIG. 2 is a graph showing a result of a durability test using an actual refrigerating machine.

FIG. 3 is a circuit diagram of a refrigeration cycle tester.

[Explanation of symbols]

 A Refrigerator B Rotary compressor F Dryer 1 Closed container 3 Rotary compression element 10 Roller 12 Vane 18 Mixed oil

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display area C10M 105: 06 129: 18 105: 38 129: 10 133: 40 137: 04) C10N 20:00 A 8217-4H 20:02 30:00 A 8217-4H Z 8217-4H 30:06 30:10 30:14 40:30 (72) Inventor Kiyoshi Tanaka 2-18 Keisei-hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. ( 72) Inventor Masato Watanabe 2-18 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd.

Claims (8)

[Claims] 1. A refrigerating apparatus in which a fluorohydrocarbon-based refrigerant containing no chlorine and a refrigerating machine oil are enclosed in a refrigerating cycle, wherein the refrigerating machine oil is at least selected from the group consisting of alkylbenzene oils or mineral oils. Mixed oil (hereinafter referred to as mixed oil) in which 10 to 50% of a polyol ester-based oil composed of a polyhydric alcohol and a fatty acid is contained in one kind of base oil
The polyol ester-based oil is a raw material obtained by polymerizing a trivalent or higher-valent polyol such as trimethylolpropane or pentaerythritol and a linear or side chain alkyl fatty acid without a catalyst, and has a pour point of −. 40 ° C or lower, two-liquid separation temperature is -20 ° C or lower, and total acid value is 0.02 mgK0
A refrigerating device having a viscosity of 8 to 100 cst at 40 ° C. and a viscosity index of 80 or more at H / g or less. 2. A refrigeration cycle using a fluorohydrocarbon-based refrigerant that does not contain chlorine, and a refrigerating apparatus that uses mixed oil, wherein the fluorohydrocarbon-based refrigerant has a purity of 99.95 wt% or more,
The refrigerating apparatus according to claim 1, wherein the content of the chlorine-based refrigerant is 80 ppm or less. 3. The refrigerating apparatus according to claim 1, wherein the equilibrium water content (shown by the following formula I) in the refrigerating cycle is 200 ppm or less in the initial state of operation. 4. The refrigerating apparatus according to claim 1, wherein the amount of residual oxygen in the refrigerating cycle is 0.01 vol% or less of the internal volume of the refrigerating cycle. 5. The mixed oil contains 0.1 to 0.5 wt% of a phenolic antioxidant such as 2,6 ditertiarybutyl paracresol (DBPC) as an additive. The refrigerating apparatus according to Item 1. 6. The refrigerating apparatus according to claim 1, wherein the mixed oil is added with a copper deactivator such as benzotriazole (BTA) at 20 ppm or less. 7. The refrigerating apparatus according to claim 1, wherein an extreme pressure additive such as tricresyl phosphate (TCP) of 2 wt% or less is added to the mixed oil. 8. The refrigerating apparatus according to claim 1, wherein the mixed oil contains 0.1 to 0.5 wt% of an epoxy additive.