JP2002194375A - Working medium composition for refrigeration / air conditioning and refrigeration / air conditioning apparatus using the composition - Google Patents

Abstract

(57) [Problem] To provide a refrigeration / air-conditioning working medium composition and a refrigeration / air-conditioning apparatus that improve the lubricity of a refrigerant / oil mixture and greatly improve the reliability of a compressor. In a working medium composed of a refrigerant (A) composed of isobutane or propane and a refrigerating machine oil (B) composed of a naphthenic mineral oil or a paraffinic mineral oil, a sorbitan ester is used in an amount of 0.1 to 0.1% based on a base oil. A refrigeration / air-conditioning working medium composition containing 5.0% by weight and the amount of Na in the compound is 100 ppm or less, and a refrigeration / air-conditioning apparatus using the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a working medium composition for refrigeration and air conditioning, and a refrigeration / air conditioning apparatus using a refrigerant compressor using the composition.

[0002]

2. Description of the Related Art CFCs conventionally used in refrigerators
(Chlorofluorocarbon) has been totally abolished from the viewpoint of protection of the ozone layer. HCFC2 is used in room air conditioners and has an ozone depletion potential smaller than CFC.
2 is also scheduled to be abolished from the viewpoint that ozone depletion is becoming more serious. As these alternative refrigerants, there are HFC (hydrofluorocarbon) -based refrigerants that do not contain chlorine in the molecule and do not destroy the ozone layer. Specifically, CFC12
HFC134a (1,1,1,2-tetrafluoroethane), which has thermodynamic properties close to that of (dichlorodifluoromethane), is used in refrigerators.
R410A (HFC32 / 125:
50/50% by weight) and R407C (HFC32 / 125
/ 134a: 23/25/52% by weight) is employed in room air conditioners.

[0003] However, although these HFCs do not contribute to the ozone layer depletion, regulations for HFCs are in the direction of progress from the viewpoint of preventing global warming. In Europe, refrigerators using a hydrocarbon-based refrigerant having a small global warming potential, a so-called natural refrigerant, have been commercialized as substitute refrigerants for refrigerators. In Japan, HFC was designated as a greenhouse substance at the Kyoto Conference on Global Warming Prevention (COP3) held in December 1997, and isobutane (R60) was used as a refrigerant.
0a) and the development of refrigerators and room air conditioners using propane (R290) have attracted attention.

On the other hand, refrigerating machine oil is used for a refrigerant compressor,
It plays a role of lubrication, sealing and cooling of the sliding part. In recent years, refrigerant compressors have been required to have energy saving, downsizing, low noise, and high efficiency, and the use conditions of refrigerating machine oil have become severer. For this reason, from the viewpoint of securing the reliability of the compressor, a refrigerating machine oil having excellent lubricating properties, particularly excellent wear resistance, is required.

As refrigeration oils, naphthenic or paraffinic mineral oils and alkylbenzenes have been widely used because of their good compatibility with CFC-based refrigerants and their low cost.

[0006] Hydrocarbon refrigerants compatible with global warming have too high a solubility in these refrigerating machine oils, and there is a concern that poor lubrication of the compressor occurs due to a decrease in the viscosity of the refrigerant / oil mixture. In addition, the working medium using a hydrocarbon-based refrigerant is different from CFC and HCFC-based refrigerants containing chlorine and fluorine in molecules.
The lubricity of the refrigerant itself cannot be expected. Furthermore, in order to increase the efficiency of reciprocating refrigerant compressors, which are the mainstream compressors in refrigerators, the viscosity of refrigerating machine oil tends to decrease, lubricating properties decrease, and the reliability of the compressor decreases. There is. In addition, a refrigerating machine oil excellent in lubricity is expected from a viewpoint of high efficiency also in a scroll type refrigerant compressor which is a mainstream as a compressor of a room air conditioner.

[0007] In connection with the above problem, as an additive for improving the lubricity of the refrigerating machine oil, Japanese Unexamined Patent Application Publication No. 11-029766 has been used.
JP-A-9-157676, JP-A-3-199926
, WO 91/09097 and JP-A-4-337391 are known. However, these additives do not provide sufficient lubricating properties, or they are poorly soluble in hydrocarbon refrigerants and precipitate at low temperatures, causing clogging of the refrigeration cycle. In addition, there is a problem that the electric insulation property is reduced by being blended in the composition.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above,
An object of the present invention is to provide a working medium composition for refrigeration and air conditioning that does not reduce the lubricity of a refrigerant / oil mixture, low-temperature solubility with a refrigerant, and electrical insulation.

Further, a refrigerating / air-conditioning apparatus which suppresses abrasion of a sliding portion of a compressor, does not cause clogging of a capillary tube, an expansion valve, and piping, has excellent electrical insulation properties, and greatly improves reliability. To provide.

[0010]

Means for solving the problems Specific means for solving the problems are as follows. (1) In a working medium containing a base oil from a naphthenic mineral oil or a paraffinic mineral oil as a refrigerating machine oil,

[0011]

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Wherein R is an alkyl group having 11 to 17 carbon atoms or a hydrocarbon group having an unsaturated bond, the sorbitan ester represented by the formula:
% By weight and Na in the sorbitan ester
A working medium composition for refrigeration / air conditioning characterized in that the amount is 100 ppm or less. (2) A refrigeration / air-conditioning apparatus provided with a refrigeration cycle for circulating refrigerant gas discharged from a refrigerant compressor having a refrigeration / air-conditioning working medium through a condensing means, an expansion means, and an evaporating means. The medium includes a refrigerant composed of isobutane or propane, and a base oil composed of naphthenic mineral oil or paraffinic mineral oil as a refrigerating machine oil, wherein R is an alkyl group having 11 to 17 carbon atoms or a non-alkyl group. Sorbitan ester represented by the formula (1) is contained in an amount of 0.1 to 5.0% by weight based on the base oil, and the amount of Na in the sorbitan ester is 100 ppm or less. A refrigeration / air-conditioning device characterized by the following.

The sorbitan ester may be a sorbitan ester of cis-9-octadecenoic acid.

The refrigerant for the working medium composition for refrigeration and air conditioning includes isobutane and propane. These refrigerants cannot expect lubricity of the refrigerant itself as compared with CFC or HCFC-based refrigerants containing chlorine in the molecule, and reduce the wear resistance of the compressor.

By using the working medium composition for refrigeration / air conditioning of the present invention, the working medium for refrigeration / air conditioning which can greatly improve the lubricity of the refrigerant / oil mixture, and has excellent solubility and electrical insulation. A composition can be obtained.

The refrigerating machine oil is based on a naphthenic mineral oil or a paraffinic mineral oil, and the viscosity grade used depends on the type of compressor. The viscosity at 40 ° C of the reciprocating refrigerant compressor is 7 to 25 mm ² / s, and the viscosity at 40 ° C of the scroll refrigerant compressor is 50 to 70 mm ² / s.
Is preferable.

The sorbitan ester as an additive is sorbitan of dodecanoic acid represented by the following general formula (wherein R represents an alkyl group having 11 to 17 carbon atoms or a hydrocarbon group having an unsaturated bond). Esters, sorbitan esters of tetradecanoic acid, sorbitan esters of hexadecanoic acid, sorbitan esters of octadecanoic acid, cis
Sorbitan ester of -4-dodecenoic acid, sorbitan ester of cis-4-tetradecenoic acid, sorbitan ester of cis-5-tetradecenoic acid, sorbitan ester of cis-9-tetradecenoic acid, sorbitan ester of cis-6-hexadecenoic acid, cis Sorbitan ester of -9-hexadecenoic acid, sorbitan ester of cis-6-octadecenoic acid, sorbitan ester of cis-9-octadecenoic acid, sorbitan ester of trans-9-octadecenoic acid, sorbitan ester of cis-11-octadecenoic acid, trans And sorbitan esters of -11-octadecenoic acid.

The mixing ratio of the additives is 0.1 to 0.1 with respect to the base oil.
The content is 5.0% by weight, and more preferably 0.1 to 1.0% by weight. If the amount of the sorbitan ester is less than 0.1% by weight, sufficient lubricity cannot be obtained, and
If it exceeds 0% by weight, solubility in a refrigerant is poor, and precipitation at a low temperature becomes easy. For this reason, it causes a clogging phenomenon of the capillary tube, the expansion valve, and the piping, which are components of the refrigeration cycle. In general, the refrigerant compressor has a built-in motor and a terminal for supplying power. If the compounding ratio is too large, the electrical insulation property is reduced, and there is a risk that a short circuit between terminals or an increase in leakage current may occur.

In the present invention, an antioxidant, an acid scavenger, an antifoaming agent, a metal deactivator, and the like may be added to the working medium composition.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The sorbitan ester used in the present invention is widely used as a nonionic surfactant for foods and cosmetics. However, Na (IC
P: analyzed by inductively coupled plasma emission spectroscopy) is usually 300
Since it is mixed in about １０００1000 ppm (analyzed by atomic absorption spectroscopy), adding it to refrigerating machine oil causes a significant decrease in electrical insulation. Therefore, the additive was treated with an ion-exchange resin to reduce the amount of Na in the additive to 100 ppm or less. The processing method is described below.

The additive is diluted with a good solvent having a boiling point of about 40 to 80 ° C. in a container, treated with NaOH in advance, washed with water and dried, and ion-exchange resin Amberlyst A-27 (manufactured by Organo) and Amberlyst 15 (Manufactured by the company) is mixed in a certain ratio, and the mixture is put in a predetermined amount in a solvent. After stirring with a stirrer for 3 hours (the ion exchange resin was replaced three times), the ion exchange resin was removed with a filter paper. The fine powder of the ion exchange resin was removed with a 0.2 μm millipore filter. Evaporate the solvent at a temperature near the boiling point and remove it to some extent. Solvent with a vacuum pump (heat the vessel to near the boiling point)
Was completely removed. The amount of Na in the additive after treatment is 100
ppm or less.

Similar results were obtained by the column method for the treatment with the ion exchange resin. The amount of Na in the additive is 10
Any method may be used as long as it can be set to 0 ppm or less. (Examples 1 to 5 and Comparative Examples 1 to 5) In Examples 1 to 5 and Comparative Examples 1 to 5, the following compounds were used. Refrigerant: (A) Propane (R290) Base oil: (A) Naphthenic mineral oil 40 ° C viscosity 54.6 mm ² / s Additive: (A) Sorbitan ester of dodecanoic acid (Na content: 10)
(0 ppm or less) (B) Sorbitan ester of tetradecanoic acid (Na content:
(C) Sorbitan ester of hexadecanoic acid (Na content:
(D) Sorbitan ester of octadecanoic acid (Na content:
(E) sorbitan ester of cis-9-octadecenoic acid (Na content: 100 ppm or less) (F) cis-9-octadecenoate glyceride

[0023]

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(G) Sorbitan ester of octadecenoic acid (Na content: about 500 ppm) (H) Sorbitan ester of cis-9-octadecenoic acid (Na content: about 200 ppm) (I) Sorbitan ester of cis-9-octadecenoic acid ( Na amount: about 600 ppm) In Examples 1 to 5 and Comparative Examples 1 to 5, the type of additive was changed, and a lubricating test of a refrigerant / oil mixture, a precipitate confirmation test in the presence of a refrigerant, and a test of refrigerating machine oil were performed. Volume resistivity measurements were performed.
The test method is shown below. (Lubricity test) In the lubricity test, the mixing ratio of the refrigerant and the refrigerating machine oil was set to 20/80 (weight ratio). A high-pressure atmosphere friction tester capable of evaluating the lubricity of the refrigerating machine oil in the presence of a refrigerant was used for the apparatus. In this device, the friction portion is present in the pressure vessel. For the test specimen material, gray cast iron was used for both the rotating test piece and the fixed test piece. The shape of the rotating test piece was outer diameter φ20 × inner diameter φ10 × height 12 mm, and the fixed test piece was outer diameter φ20 × inner diameter φ.
10 × 8 mm high, 4 mm wide ×
3mm deep oil groove is cut. The test method is as follows. First, a jig and a load cell are set in a pressure vessel, and a test piece sufficiently washed with toluene (10 min × 3 times) is set. Refrigerant / refrigeration oil mixed liquid amount is 1 beforehand
Refrigerant and refrigerating machine oil were collected in a pressure-resistant glass container so that the volume became 60 ml.
A refrigerant / oil mixture is introduced into the pressure vessel.

The test conditions were as follows.
The test was performed at 49 kN and a rotation speed of 1200 min ^-1 for 15 minutes. After that, load 0.98kN (contact pressure 7.16MPa),
The rotation speed was 1200 min ^-1 (slip speed 1.0 m / s), the ambient temperature was room temperature, and the friction time was 10 hours. The measurement items are the test specimen weight before and after operation and the coefficient of friction. The amount of abrasion was defined as the total amount of abrasion of the rotating test piece and the fixed test piece, and the coefficient of friction used was the total average value at 10-sec intervals. The mixing ratio of all additives was 0.5% by weight with respect to the base oil. (Precipitate Confirmation Test) The precipitate confirmation test in the presence of a refrigerant was conducted by placing the refrigerant and the refrigerating machine oil in a pressure-resistant glass container at 80/20 (weight ratio).
And a precipitate was observed when the mixture was left in a low-temperature constant temperature bath at −30 ° C. for 12 hours. If the solubility of the additive in the refrigerant is poor, a white precipitate accumulates at the bottom of the container. (Volume resistivity measurement) The volume resistivity of the refrigerating machine oil was measured in accordance with JIS C 2101 using an insulating oil measuring electrode made of nickel-plated brass.

Table 1 shows the above test results.

[0027]

[Table 1]

It is desired that the working medium composition for refrigeration and air conditioning not only has the lubricity of the additive but also satisfies all the properties of solubility and electrical insulation. Therefore, the target values in the examples are as follows: wear amount 3.0 mg or less, friction coefficient 0.05 or less, no precipitate at low temperature, and volume resistivity of 1 ×
It was 10 ¹³ Ω · cm or more.

The working medium composition for refrigeration and air conditioning which does not contain the additives shown in Comparative Example 1 of Table 1 has a large amount of wear and a very high coefficient of friction, and therefore has poor lubricity. In addition, in the case of Comparative Example 2, although the lubricity was improved, precipitates were confirmed at a low temperature, and further, the volume resistivity was significantly reduced. The sorbitan esters having a Na content of 100 ppm or more in Comparative Examples 3 to 5 have a low volume resistivity.

On the other hand, as is apparent from Examples 1 to 5, the working medium composition for refrigeration and air conditioning of the present invention is obtained by blending a sorbitan ester having a Na content of 100 ppm or less with a naphthenic mineral oil. In addition, a working medium composition for refrigeration and air-conditioning that can significantly reduce the amount of wear and the coefficient of friction, has no precipitates at low temperatures, and satisfies the volume resistivity can be obtained. (Examples 6 to 11 and Comparative Examples 6 to 10) Examples 6-1
1, In Comparative Examples 6 to 10, the following compounds were used. Refrigerant: (B) Isobutane (R600a) Base oil: (B) Naphthenic mineral oil 40 ° C viscosity 12.3 mm ² / s (C) Naphthenic mineral oil 40 ° C viscosity 18.9 mm ² / s (D) Paraffinic mineral oil 40 ° C Viscosity 15.3 mm ² / s (E) Paraffinic mineral oil 40 ° C viscosity 21.8 mm ² / s Additives: (E) Sorbitan ester of cis-9-octadecenoic acid (N
(a quantity: 100 ppm or less) In Examples 6 to 11 and Comparative Examples 6 to 10, the effect was obtained in Example 5 in which isobutane was used as a refrigerant, and naphthenic mineral oil and paraffinic mineral oil having different viscosities were used as base oils. Table 1 shows the results of the same tests as in Examples 1 to 5 performed using the additive E and changing the mixing ratio.

In the working medium for refrigeration and air conditioning in which the additives of Comparative Examples 6, 9, and 10 are not blended, the amount of wear is large and the coefficient of friction is very high, so that the lubricity is inferior. In particular, Comparative Example 9,
In the working medium composition for refrigeration / air-conditioning indicated by 10, the test pieces were in contact with each other during the test and caused seizure causing transfer, and the measurement of the wear amount and the friction coefficient could not be performed.

On the other hand, as shown in Examples 6, 8, 10, and 11, the working medium composition for refrigeration and air conditioning of the present invention can be used in Example 1 even when isobutane is used as the type and viscosity of the base oil and the refrigerant. As in the case of Nos. 1 to 5, the amount of wear and the coefficient of friction can be greatly reduced, and a working medium composition for refrigeration and air conditioning that has no precipitate at low temperature and satisfies the volume resistivity can be obtained.

Further, as shown in Comparative Examples 7 and 8, when the blending ratio of the sorbitan ester is less than 0.1% by weight, sufficient lubricity cannot be obtained, and when it exceeds 5% by weight, the additive precipitates at a low temperature. , And the volume resistivity further decreases. On the other hand, as shown in Examples 7 to 9, the compounding ratio with respect to the base oil was 0.1%.
By setting the content to 1 to 5.0% by weight, a working medium composition for refrigeration and air conditioning satisfying the target value can be obtained. The mixing ratio of the additive is more preferably 0.1 to 1.0% by weight from the viewpoint of low-temperature solubility and decrease in electrical insulation. (Examples 12 to 18 and Comparative Examples 11 to 17) Refrigeration compressors for refrigeration / air conditioners include scroll, reciprocating, screw, rotary type fixed displacement compressors and turbo type displacement compressors.

FIG. 1 schematically shows a room air conditioner which is used for both cooling and heating in this embodiment. In order to cool the room, the high-temperature and high-pressure refrigerant gas adiabatically compressed from the discharge pipe of the compressor 1 passes through the four-way valve 2 and is cooled by the outdoor heat exchanger 3 (used as a condensing means). It becomes a refrigerant. This refrigerant is expanded by expansion means 4 (for example, a capillary tube or a temperature-type expansion valve), becomes a low-temperature low-pressure liquid containing a slight amount of gas, reaches an indoor heat exchanger 5 (used as evaporating means), and Then, heat is obtained from the air to reach the compressor 1 again through the four-way valve 2 in the state of a low-temperature gas. When heating the room, the flow of the refrigerant is changed by the four-way valve 2 in the opposite direction, and the operation is reversed.

A scroll compressor was used as the compressor. The schematic structure is shown in FIG. The compressor wraps a spiral wrap 8 standing upright on an end plate 7 of a fixed scroll member 6 and an orbiting scroll member 9 composed of an end plate 9 and a wrap 10 having substantially the same shape as the fixed scroll member 6. The compression mechanism is formed by meshing the wrap 10 with the wrap 10 facing each other, and the orbiting scroll member 9 is orbited by the crankshaft 11. Of the compression chambers 12 formed by the fixed scroll member 6 and the orbiting scroll member 9, the outermost compression chamber has its center gradually reduced with the orbital movement while its volume is gradually reduced. Move toward. When the compression chambers 12a and 12b reach the vicinity of the centers of the scroll members 6 and 9, the compression chambers 12a and 12b communicate with the discharge port 13 and the compressed gas in both compression chambers is discharged from the discharge pipe 16 to the outside of the compressor. Is discharged.

In this compressor, an electric motor 17 is built in the pressure vessel 15, and the compressor rotates the crankshaft 11 at a constant speed or at a rotation speed corresponding to a voltage controlled by an inverter (not shown). Perform the operation. An oil reservoir is provided at a lower portion of the motor 17, and the oil passes through an oil hole 18 provided in the crankshaft due to a pressure difference, and slides between the orbiting scroll member 9 and the crankshaft 11. It is used for lubrication of the bearing 19 and the like.

In Examples 12 to 18 and Comparative Examples 11 to 17, the room air conditioner shown in FIG. 1 was used.
(75% humidity) and an operation test for 2160 hours. As the combination of the refrigerant, the base oil, and the additive, the same compounds as those in Examples 1 to 5 were used. Comparative Examples 11 to
For 17, the compounds described in Comparative Examples 1 to 5 were used. In the evaluation of the room air conditioner, the wear state of the scroll compressor was observed, and the amount of increase in the gap due to wear between the frame and the shaft before and after the test was measured. It shows that the amount of wear increases as the amount of increase in the gap between the frame and the shaft increases,
Generally, vibration and noise increase as the amount of increase in the gap increases.

In Examples 12 to 18 and Comparative Examples 11 to 17 using the room air conditioner shown in FIG. 1, the Japan Refrigeration and Air Conditioning Industry Association Standard (JRA4046: Standard for calculating the period power consumption of the room air conditioner). Based on the above, a power consumption test was performed to calculate the period power consumption. Here, the period power consumption of Comparative Example 11 is shown as 100%.

Further, after the test, the evaporator, the expansion valve, and the pipe were opened to check for the presence of the deposit. If a large amount of additive precipitates in the evaporator and reaches a large amount, the efficiency of the room air conditioner is reduced. Since the motor for the room air conditioner is arranged in the compressor, a high-frequency leakage current flows between the motor winding and the case. Leakage current is regulated by the Electrical Appliance and Material Handling Law to ensure safety to the human body. Therefore, Examples 12 to 18
In the example, after operating at the rated voltage and the rated frequency under the cooling and heating conditions and the refrigerating cycle was stabilized, the maximum leakage current between the charged part and the ground was measured. Here, the maximum leakage current of Comparative Example 11 is shown as 100%.

The target value of this test is that the amount of increase in the gap due to wear between the frame and the shaft is 15 μm or less, and the periodical power consumption is less than 100% when the comparative example 11 is 100%. The goal was to satisfy all of the following criteria: no deposits on the piping, and a maximum leakage current of less than 200%. Table 2 shows the results of Examples and Comparative Examples.

[0041]

[Table 2]

As is clear from Table 2, Examples 12 to 1
The room air conditioner of the present invention indicated by 6 has a Na content of 100
By using the working medium for refrigeration and air conditioning blended with the sorbitan ester of not more than ppm, compared with the working medium for refrigeration and air conditioning without blending the additive of Comparative Example 11,
The amount of increase in the gap between the shafts can be greatly reduced and wear can be suppressed, so that high reliability can be obtained in a room air conditioner. No deposits were found on the evaporator, expansion valve, or piping. Further, as compared with Comparative Example 11, the frictional resistance inside the compressor is reduced, the period power consumption is reduced, and the increase in the maximum leakage current is also small.

On the other hand, in the case of Comparative Example 12, although the amount of increase in the gap between the frame and the shaft was suppressed, precipitates were confirmed at a low temperature, and the maximum leakage current value was significantly increased. . In Comparative Examples 13 to 15, the amount of Na was 100 pp.
Even when a sorbitan ester of m or more is used, the maximum leakage current value greatly increases.

Further, as shown in Comparative Examples 16 and 17 in Table 2, in a room air conditioner using a refrigeration / air conditioning working medium containing less than 0.1% by weight of a sorbitan ester, a gap between a frame and a shaft was used. When the amount of increase is not sufficiently suppressed, if it exceeds 5% by weight, the additive is deposited on the evaporator, the expansion valve, and the piping, and the maximum leakage current value also increases. On the other hand, as shown in Examples 16 to 18, a room air conditioner satisfying the target value can be obtained by setting the blending ratio to the base oil to be 0.1 to 5.0% by weight. The mixing ratio of the additive is more preferably 0.1 to 1.0% by weight from the viewpoint of precipitation at low temperatures and increase in leakage current value. (Examples 19 to 24 and Comparative Examples 18 to 22) FIGS. 3A and 3B show specific examples of the refrigerator of this example. The refrigerator box 20 has a refrigerator compartment 21 and a freezer compartment 22, both of which are separated by a wall. The refrigerating cycle for cooling the inside of the refrigerator includes a compressor 23, a condenser 24, a dehydrator 25, a capillary tube, an evaporator 26, and a blower fan 27. The cool air cooled by the evaporator 26 is supplied to a blower fan 27.
Is sent to the freezer compartment 22, and then passes through the damper 28 as shown by the arrow in the drawing, and is sent to the refrigerator compartment 21 to be sent to the refrigerator compartment 21.
The flow path is again cooled by the evaporator 26 through the flow path. Next, the refrigerating cycle of the refrigerator shown in FIG. 3 will be described. FIG. 4 shows a basic refrigeration cycle configuration diagram of the refrigerator.

The compressor 23 compresses the low-temperature, low-pressure refrigerant gas, discharges the high-temperature, high-pressure refrigerant gas and sends it to the condenser 24. The refrigerant gas sent to the condenser 24 becomes a high-temperature, high-pressure refrigerant liquid while releasing its heat into the air,
Through the capillary tube 29. The high-temperature, high-pressure refrigerant liquid passing through the capillary tube 29 becomes low-temperature, low-pressure wet vapor by the throttle effect and is sent to the evaporator 26. The refrigerant that has entered the evaporator 26 absorbs heat from the surroundings and evaporates, and sends cool air into the box by the blower fan 27. The low-temperature, low-pressure refrigerant gas exiting the evaporator 26 is supplied to the compressor 2
3, and the same cycle is repeated thereafter.

Refrigerant compressors for refrigerators are mainly reciprocating and rotary type equal displacement compressors. FIG. 5 shows a schematic structure of a reciprocating refrigerant compressor as an example of the compression means.

In general, a reciprocating type refrigerant compressor has a compressor 31 and a motor 31 housed in a sealed container 30 and stores refrigeration oil 32 at the bottom of the sealed container. A slidable piston 34 is fitted into the inner diameter of the cylinder 33 constituting the compression section, and the piston 34 reciprocates in the cylinder 33 due to the eccentric rotation of the crankshaft 35 of the rotating shaft that transmits the rotating force of the motor 31. And thereby sucks in refrigerant gas,
It has a structure to compress and discharge. The compressed refrigerant gas is discharged to an external refrigeration cycle by a discharge pipe 36. An oil reservoir is provided at a lower portion of the motor 31, and the oil is supplied to an oil hole 3 provided in a crankshaft 35.
7 to the lubrication of each sliding part of the compressor.

In Examples 19 to 24, isobutane was used as a refrigerant, a naphthenic mineral oil and a paraffinic mineral oil having different viscosities were used as a base oil, and an additive E obtained in Examples 16 to 18 was used. The test was performed by changing the mixing ratio. An actual machine test was conducted in which the working medium composition for refrigeration / air conditioning of the present invention was sealed in a refrigerator shown in FIG. 3 and operated in a constant temperature room (40 ° C.) for 2160 hours. In the evaluation of the refrigerator, the wear state of the reciprocating compressor was focused on, and the increase in the gap due to the wear between the frame and the shaft before and after the test was measured. flame~
This indicates that the greater the amount of increase in the clearance between the shafts, the greater the amount of wear. Generally, as the amount of increase in the clearance increases, vibration and noise increase. In addition, the capillary tube after the test was opened to examine the presence or absence of attached matter. When a large amount of deposits are contained in the capillary tube and the blockage occurs, the refrigerator may be poorly cooled.

Further, using the refrigerators of Examples 19 to 24, a power consumption test was performed in accordance with the new JIS C 9801 (characteristics and test method of household electric refrigerator and electric freezer) to calculate the annual power consumption. Here, the annual power consumption of Comparative Example 18 is shown as 100%.

The target value of this test is that the amount of increase in the gap due to wear between the frame and the shaft is 15 μm or less, and the annual power consumption is less than 100% when Comparative Example 18 is 100%. The goal was to satisfy all items of no kimono and a maximum leakage current value of less than 200%. Table 3 shows the results of Examples 19 to 24 and Comparative Examples 18 to 22.

[0051]

[Table 3]

As apparent from Table 3, Examples 19 to 2
The refrigerator of the present invention indicated by No. 4 was a comparative example 18, 21, 22.
Compared with the working medium composition for refrigeration and air-conditioning using only naphthenic mineral oil and paraffinic mineral oil alone, the amount of increase in the gap between the frame and the shaft can be greatly reduced, and high reliability is obtained in the refrigerator by suppressing wear. Can be Also, no deposit was found on the capillary tube. Furthermore,
As shown in Examples 19 to 24, compared to Comparative Example 18, the refrigerator of the present invention has a reduced frictional resistance inside the compressor, and thus has a reduced annual power consumption.

As shown in the refrigerators of Comparative Examples 19 and 20, in the refrigerator using the working medium for refrigeration and air conditioning in which the blending ratio of the sorbitan ester to the base oil was less than 0.1% by weight, the gap between the frame and the shaft was used. When the amount of increase is not sufficiently suppressed, when the amount exceeds 5% by weight, the additive precipitates in the capillary tube, and the maximum leakage current value also increases.
On the other hand, a refrigerator satisfying all target values can be obtained by setting the blending ratio with respect to the base oil to 0.1 to 5.0% by weight as shown in Examples 20 to 22. The mixing ratio of the additive is more preferably from 0.1 to 1.0% by weight from the viewpoint of precipitation at low temperatures and an increase in leakage current value.

From the above results, in the working medium composed of the refrigerant (A) composed of isobutane or propane and the refrigerating machine oil (B) composed of naphthenic mineral oil or paraffinic mineral oil, the following general formula (wherein R is carbon number 1
And 1 to 17 alkyl groups or hydrocarbon groups having an unsaturated bond. The working medium composition for refrigeration / air conditioning, which contains the sorbitan ester represented by the formula (1) in an amount of 0.1 to 5.0% by weight with respect to the base oil and has a Na content of 100 ppm or less in the compound, It was confirmed that the lubricating property was improved and the thermal stability was excellent.

In a refrigeration / air-conditioning apparatus using the composition, wear of a compressor in the refrigeration / air-conditioning apparatus is suppressed,
In addition, it was confirmed that there was no deposit in the low temperature part of the refrigeration cycle, no clogging occurred, the leakage current value was not increased, and the annual power consumption was reduced.

[0056]

The working medium composition for refrigeration and air conditioning of the present invention has an effect of improving lubricity. In addition, the frozen /
The air conditioner has the effect of suppressing poor lubrication of the compressor in the refrigeration / air conditioner without lowering the electrical insulation, preventing blockage in the refrigeration cycle low temperature part, and further reducing annual power consumption. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a room air conditioner.

FIG. 2 is a sectional view illustrating a scroll-type refrigerant compressor.

FIG. 3 is a sectional view illustrating a refrigerator.

FIG. 4 is a diagram illustrating a refrigeration cycle of a refrigerator.

FIG. 5 is a cross-sectional view illustrating a reciprocating refrigerant compressor.

[Explanation of symbols]

1,23 ... Compressor, 2 ... 4-way valve, 3 ... Outdoor heat exchanger, 4
... Expansion means, 5 ... Indoor heat exchanger, 6 ... Fixed scroll member, 7 ... End plate, 8 ... Swirl wrap, 9 ... Swirl scroll member, 10 ... Lap, 11 ... Crank shaft, 12 ...
Compression chamber, 13: discharge port, 14: frame, 15: compression container, 16, 36: discharge pipe, 17: electric motor, 18
... oil hole, 19 ... sliding bearing, 20 ... box body, 21 ... refrigerator compartment, 22 ... freezer compartment, 24 ... condenser, 25 ... dehydrator, 26
... Evaporator, 27 ... Blower fan, 28 ... Damper, 29 ...
Capillary tube, 30: sealed container, 31: motor, 32: refrigerating machine oil, 33: cylinder, 34: piston, 35: crankshaft, 37: oil hole.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C10N 40:30 C10N 40:30 (72) Inventor Toshi Iizuka 800 Tomita, Odaira, Ohira-cho, Shimotsuga-gun, Tochigi Prefecture Hitachi Tochigi Technology Co., Ltd. F-term (reference) 4H104 BB35C DA02A PA20

Claims (4)

[Claims] 1. A working medium containing a refrigerant consisting of isobutane or propane and a base oil consisting of naphthenic mineral oil or paraffinic mineral oil as a refrigerating machine oil. (Wherein R is an alkyl group having 11 to 17 carbon atoms or a hydrocarbon group having an unsaturated bond) containing 0.1 to 5.0% by weight based on the base oil, And the amount of Na in the sorbitan ester is 100
A working medium composition for refrigeration and air conditioning, characterized in that the content is less than ppm. 2. The refrigeration / air-conditioning working medium composition according to claim 1, wherein the sorbitan ester is a sorbitan ester of cis-9-octadecenoic acid. 3. A refrigeration / air-conditioning apparatus comprising a refrigeration cycle for circulating refrigerant gas discharged from a refrigerant compressor having a refrigeration / air-conditioning working medium through a condensing means, an expansion means, and an evaporating means. The working medium for use includes a refrigerant composed of isobutane or propane, and a base oil composed of naphthenic mineral oil or paraffinic mineral oil as a refrigerating machine oil, and has a general formula (1). (Wherein R is an alkyl group having 11 to 17 carbon atoms or a hydrocarbon group having an unsaturated bond) containing 0.1 to 5.0% by weight based on the base oil, And the amount of Na in the sorbitan ester is 100
A refrigeration / air-conditioning system characterized by being below ppm. 4. The refrigeration / air-conditioning apparatus according to claim 3, wherein the sorbitan ester is a sorbitan ester of cis-9-octadecenoic acid.