JP2882279B2 - Refrigerant circulation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant circulation system mainly using, for example, a refrigerant mainly composed of hydrofluorocarbon or a third generation refrigerant.

[0002]

2. Description of the Related Art An example of a conventional refrigerant circulation system is shown in FIG.
Shown in Conventionally, for example, as shown in Tripolist Vol. 35, No. 9 (1990), pp. 621 to 626, when a refrigeration apparatus is constituted by using a HFC134a refrigerant which is a hydrofluorocarbon, mutual melting of the refrigerant and the refrigeration oil is performed. The property is one of the important characteristics, and PAG (polyether) or ester-based refrigerator oil has been used. FIG. 11 shows a refrigeration system using HFC134a refrigerant, 1 is a compressor for compressing refrigerant gas, 2 is a condenser for condensing high-pressure refrigerant gas discharged from the compressor 1, 3 is a throttle mechanism, and 4 is an evaporator. Reference numeral 5 denotes a four-way valve having a function of reversing the flow direction of the refrigerant, 8 denotes an accumulator having a refrigerant amount adjusting function, and 6 denotes lubrication of a sliding portion of the compressor 1 stored in the compressor 1. And PAG 6a or ester-based refrigerating machine oil 6b.

Next, the behavior of oil will be described. Compressor 1
Is discharged to the condenser 2. Most of the lubricating oil 6a or 6b used for lubrication of the compressor and sealing of the compression chamber returns to the bottom, but the oil 6a or 6b of about 0.5 to 3.0% in terms of the weight ratio with respect to the refrigerant is The refrigerant is discharged from the compressor 1 together with the refrigerant. Since the discharged oil 6a or 6b has mutual solubility with the refrigerant, it has good fluidity, passes through the condenser 2, the capillary tube 3, and the evaporator 4, enters the accumulator 8, and is dissolved in the surplus liquid refrigerant 7a.
It returns to the compressor 1 through the oil return hole 82. Therefore, the lubricating oil 6 does not disappear from the compressor 1 and normal lubrication becomes possible.

FIG. 15 shows another example of a conventional refrigerant circulation system.
Shown in Conventionally, for example, as disclosed in JP-A-5-17789, a highly soluble refrigerant such as an ester-based refrigerating machine oil has been used in a refrigerant circulation system using a mixed refrigerant containing HFC32 which is a flammable refrigerant. Was. For example,
FIG. 15 shows an air conditioner using a mixed refrigerant constituted by HFC32, HFC125, and HFC134a,
1 is a compressor for compressing the refrigerant gas, 2 is a condenser for condensing the high-pressure refrigerant gas discharged from the compressor 1, 3 is a throttle mechanism, 4 is an evaporator, and 5 has a function of reversing the flow of the refrigerant. Reference numeral 8 denotes an accumulator having a refrigerant amount adjusting function. Reference numeral 6 denotes a refrigerating machine oil for lubricating a sliding portion of the compressor 1 and sealing of a compression chamber, and is an ester-based refrigerating machine oil 6b. The refrigerant sucked into the compressor 1 cools the electric motor 12 in the closed vessel 11 and then cools the compressor mechanism 13.
And is discharged to the condenser 2 through the four-way valve 5. In this process, the refrigerating machine oil 6 stored at the bottom of the closed container 11 is structurally exposed to the refrigerant atmosphere sucked into the compressor 1. However, since the refrigerating machine oil 6 has high solubility, a large amount of refrigerant is used. Will dissolve.

[0005]

The conventional HFC134a
Is configured as described above,
PAG (polyether) 6a has a volume resistivity of 10 ⁷ to 1
0 ¹⁰ Ω · cm, the saturated water content is about 25000 ppM, and the characteristics of the ester-based refrigerating machine oil are 10 ¹² to 1 respectively.
Although it has been improved to 0 ¹⁴ Ω · cm and about 1500 ppM, the characteristics of the current refrigerating machine oil for CFC12 10 ¹⁵ Ω · cm,
Compared with about 300 ppM, it shows considerably inferior properties in electrical insulation and hygroscopicity.

[0006] Hydrofluorocarbon (HFC)
Is a promising alternative to CFC12 and HCFC22, which are subject to reduction and decommissioning plans due to environmental issues. In general, this hydrofluorocarbon is
Refrigeration oil having higher polarity than HCHC22 or HCHC22 and having high mutual solubility generally has higher polarity. Therefore, oil having mutual solubility with hydrofluorocarbon is easily adsorbed to highly polar water. As a result, moisture is introduced into the refrigerant circulation system, and the electrical insulation is reduced. Further, hydrolyzable substances such as ester oil as a refrigerating machine oil and organic materials used in a compressor are easily deteriorated. There is a possibility that the performance of the refrigerant circulation system may be degraded due to accumulation of the objects in the throttle mechanism.

Therefore, when assembling the refrigerant circulation system,
There are many production handling problems such as shortening the time that the system is left open to the atmosphere, and if too much water enters the system, it accelerates the generation of sludge and freezes the water, causing the squeezing mechanism to operate. There were problems such as blockage and poor cooling.

Further, in the conventional refrigerant circulation system of the HFC134a, in the case of after-sales service such as repair and replacement of system components, the moisture in the air is adsorbed by the refrigerator oil due to the high hygroscopicity of the refrigerator oil, and the throttle mechanism Capillary tubes and expansion valves freeze and easily block, and the formation of sludge due to the promotion of hydrolysis of ester oil by water,
Sludge is generated due to promotion of hydrolysis of polyethylene terephthalate used as an insulating material for the motor. In order to prevent such defects in the manufacturing process and after-sales service, it is necessary to carefully remove the water of the refrigerating machine oil and the water in the refrigerant cycle as compared with the system using the CFC12 refrigerant, and to install a dryer in the refrigerant cycle. There is a problem that it is necessary to provide a water supplement function.

When a refrigerating machine oil having high mutual solubility is used, the refrigerating machine oil or the refrigerant in contact with the refrigerating machine oil rapidly refrigerates as the temperature approaches the saturation temperature of the refrigerant at the atmospheric pressure where the refrigerating machine oil is placed. The amount of refrigerant dissolved in the machine oil increases. Therefore, since the refrigerating machine oil is diluted into a refrigerant having a lower viscosity than the refrigerating machine oil, the viscosity of the liquid supplied to the sliding portion is extremely reduced, and the lubricating characteristics of the sliding portion are deteriorated, which may cause seizure. was there.

[0010] When the bottom of the compressor in which the refrigerating oil having high mutual solubility is stored is disposed on the high pressure side, the surface pressure of the sliding portion in the compressor becomes higher, and the higher the pressure in the high pressure atmosphere in which lubrication is required, the more the refrigerant becomes. The solubility was increased, the viscosity of the liquid supplied to the sliding portion was reduced, and the lubricating properties of the sliding portion were deteriorated, possibly causing seizure or the like. Therefore, conventionally, when the bottom of the compressor where the refrigerating oil having high mutual solubility is stored is disposed on the high pressure side, the refrigerating oil having a high viscosity has been used in consideration of the melting and mixing of the refrigerating oil at the high pressure. Conversely, in a low-pressure atmosphere, the viscosity of the refrigerant becomes very high because the refrigerant is less dissolved, and the ratio of the mechanical loss generated by the shearing force of the oil in the sliding bearing portion to the compression work becomes large, resulting in a problem that the efficiency is reduced. .

In the case of using refrigerating machine oil having high mutual solubility, a large amount of refrigerant is contained in oil leaked to the suction side of the compression chamber at the oil seal portion, and this refrigerant re-expands and re-compresses in the compression process. As a result, there is a problem that a loss occurs and efficiency is reduced.

Further, the conventional refrigerant circulation system is a mixed refrigerant of a plurality of refrigerants and at least one of the constituent refrigerants.
The species are flammable refrigerants, such as HFC32, which is flammable as a sole refrigerant, and HFC1, which is nonflammable as a sole refrigerant.
25, when a mixed refrigerant of HFC134a is used, a large amount of refrigerant is dissolved in the refrigerant oil because the refrigerant oil has high refrigerant solubility. At this time, the amount of the refrigerant dissolved in the refrigerating machine oil differs depending on the polarity of each refrigerant.
FIG. 16 shows HFC32 and HF for ester-based refrigerating machine oil.
FIG. 3 is a view showing the solubility of C125 and HFC134a.
HFC125 and HFC134a, which have relatively weak polarities, are selectively dissolved in the refrigerating machine oil in a larger amount than HFC32, which has relatively strong polarity. As a result, the refrigerant mixture ratio in the refrigerant circulation cycle that is not dissolved in the refrigerating machine oil has a larger ratio of the flammable HFC32 alone than the non-flammable mixture ratio before being filled in the refrigerant circulation cycle. However, there is a possibility that the mixture ratio changes to a flammable one. Therefore, when the refrigerant in this state is released into the air due to some trouble or the like and there is an ignition heat source, there is a problem that a fire may occur and a fire may be caused.

In addition, at least one of the conventional constituent refrigerants
In a refrigerant circulation system that uses a mixed refrigerant of multiple refrigerants that are flammable, the refrigerant oil used is a flammable substance. There is a problem that, when the heat is released and an ignition heat source is present, there is a risk of firing and causing a fire.

Here, the term "flammable refrigerant" refers to a refrigerant that ignites when it comes into contact with an ignition heat source at a mixing ratio with air in a practical temperature range.
32 (R32), HFC143a (R143a), HF
C152a (R152a), propane (R290), butane (R600), pentane, ammonia (R717)
In addition, the non-combustible refrigerant refers to a refrigerant that does not ignite even in contact with an ignition heat source at a mixing ratio with any air in a practical temperature range. Here, the practical temperature range is -40.
C. to +100 C.

The present invention has been made to solve the above problems, and has excellent electrical insulation and moisture resistance.
It is another object of the present invention to provide a sufficiently reliable refrigerant circulation system by maintaining the management level of the manufacturing process and after-sales service at the conventional level.

The present invention has been made in order to solve the above-mentioned problems, and does not ignite even if it is released due to some trouble or the like and an ignition heat source is present.
It is an object of the present invention to provide a highly safe refrigerant circulation cycle that does not cause a fire or the like.

The present invention provides a refrigerant circulation system in which refrigerant and oil do not stay at inappropriate places in the refrigerant system.

[0018]

The refrigerant circulating system of the present invention uses a refrigerant containing hydrofluorocarbon as a main component, in which the refrigerating machine oil is insoluble or weakly soluble, and the refrigerant is flammable. It is a product using a mixed refrigerant of a plurality of refrigerants including:

The refrigerant circulation system of the present invention uses a refrigerant mainly containing fluoroamine, fluoroether, fluoropropane, fluoroethane, fluorosilane or fluorosulfur, and the refrigerating machine oil is insoluble or weak in the refrigerant. The refrigerant has solubility and uses a mixed refrigerant of a plurality of refrigerants containing flammability.

The refrigerant of the present invention is a plurality of refrigerants obtained by mixing non-azeotropic refrigerants.

The refrigerant circulation system according to the present invention includes a compressor that sucks a gas refrigerant or a gas refrigerant containing a liquid refrigerant partially and discharges it as a high-pressure gas refrigerant, and a liquid refrigerant that contains a liquid refrigerant or a gas refrigerant partially. The refrigerant is circulated by connecting a throttle mechanism that reduces the pressure, a condenser that condenses the high-pressure gas refrigerant discharged from the compressor, and an evaporator that evaporates the liquid refrigerant or gas-liquid two-phase refrigerant discharged from the throttle mechanism. In the refrigerant circulation system, a refrigerating machine oil for performing a lubrication or sealing function is stored in a compressor provided in the system or in a separate tank, and a part or all of the refrigerating machine oil is exposed to a refrigerant atmosphere. In the structure, the refrigerating machine oil has insolubility or weak solubility with respect to the refrigerant and at least one of the constituent refrigerants is composed of a plurality of flammable refrigerants. It is obtained by using the case refrigerant.

The refrigerating machine oil of the present invention is nonflammable.

[0023]

[0024]

[0025]

[0026]

[0027]

The present invention uses a refrigerating machine oil which is insoluble or slightly soluble in a refrigerant mainly composed of hydrofluorocarbon having a high polarity, and uses a refrigerant mixture of a plurality of refrigerants containing flammable refrigerants. Therefore, the mixture ratio of the refrigerant in the cycle hardly changes, and the mixture ratio of the combustible refrigerant hardly increases.

The present invention uses a refrigerant containing fluoroamine, fluoroether, fluoropropane, fluoroethane, fluorosilane or fluorosulfur as a main component, and the refrigerating machine oil is insoluble or weakly soluble in the liquid refrigerant. Therefore, the mixture ratio of the refrigerant in the cycle hardly changes, and the mixture ratio of the combustible refrigerant hardly increases.

[0029]

[0030]

If a non-azeotropic mixed refrigerant is used, the refrigerant is less transferred into the compressor when the system is stopped for a long time.

[0032]

The refrigerant of the present invention uses a mixed refrigerant of a plurality of flammable refrigerants, and at least one of the constituent refrigerants does not dissolve or slightly dissolves in the liquid refrigerant. The mixture ratio of the refrigerant hardly changes, and the mixture ratio of the flammable refrigerant hardly increases.

[0034]

The refrigerant circulation system does not catch fire even if the refrigerant is discharged into the atmosphere due to some trouble or the like and there is an ignition heat source, thereby avoiding the danger of causing a fire.

[0036]

[0037]

[0038]

【Example】

Embodiment 1 FIG. Hereinafter, Embodiment 1 corresponding to the present invention will be described with reference to FIGS. FIG. 1 shows an example of a refrigerant circulation system applied to, for example, a small-capacity air conditioner. In FIG. 1, reference numeral 1 denotes a compressor for compressing refrigerant gas, and reference numeral 2 denotes a condenser for condensing high-pressure refrigerant gas discharged from the compressor 1. Condenser, 3 is a throttle mechanism, 4 is an evaporator, 5 is a four-way valve having a function of reversing the flow direction of the refrigerant, 6 is stored in the compressor 1, and 6 is a sliding part of the compressor 1. Refrigeration oil for lubricating and sealing the compression chamber. FIG. 2 shows a liquid refrigerant HFC of this embodiment.
13 shows the weight dissolution rate of refrigerating machine oil alkylbenzene in 134a. It has a solubility of 0.5 to 7% by weight in the liquid refrigerant in the condenser and a non-soluble or weakly soluble in the liquid refrigerant in the evaporator of 0 to 2% by weight. Having.

Next, the behavior of the refrigerant and the oil will be described.
A part of the refrigerating machine oil that has performed the function of sealing the compression chamber is mixed with the refrigerant compressed by the compressor 1 and discharged to the condenser 2. The pipe diameter of the condenser 2 through which the refrigerant gas flows is set such that the flow rate of the refrigerant gas secures a flow velocity sufficient to convey the refrigerating machine oil downstream. The refrigerant is condensed on the inner wall surface of the pipe of the condenser 2, and the thickness of the condensed liquid increases toward the downstream side, but the gap diameter of the central portion of the pipe through which the gas flows decreases accordingly. Therefore, the gas flow velocity decreases slowly, and a critical flow velocity sufficient to continue transporting the refrigerating machine oil and the pipe wall refrigerant liquid downstream is maintained. In the vicinity of the rear end of the pipe of the condenser 2, most of the refrigerant is liquefied and the flow velocity in the pipe is remarkably reduced. However, since the refrigerating machine oil has weak compatibility with the condensed liquid refrigerant, it is dissolved in the liquid refrigerant and conveyed downstream. Is done. At the entrance of the expansion mechanism 3, the refrigerant is almost liquefied, and the refrigerating machine oil having weak compatibility is conveyed downstream together with the liquid refrigerant. In the downstream area of the expansion mechanism 3, the temperature and pressure of the refrigerant are significantly reduced, and the refrigerating machine oil has only a slight solubility in the liquid refrigerant or turns into insoluble.

However, due to the gasification of a part of the liquid refrigerant generated in the downstream area of the throttle mechanism 3, the flow velocity of the refrigerant increases rapidly, and the refrigerating machine oil is conveyed downstream. The pipe of the evaporator 4 is set to a pipe diameter sufficient for the refrigerant gas generated by the pressure drop of the throttle mechanism 3 to convey the liquid refrigerant and the refrigerating machine oil downstream.
Regardless of whether the refrigerating machine oil is insoluble or slightly soluble in the liquid refrigerant, the refrigerating machine oil is transported downstream. In the evaporator 4, the amount of the vaporized refrigerant increases toward the downstream, so that the refrigerant gas is accelerated to maintain a gas flow velocity sufficiently exceeding the critical flow velocity necessary for transporting the refrigerating machine oil, and the refrigerant gas is supplied to the compressor 1. Is sucked, and the refrigerating machine oil joins the refrigerating machine oil 6 stored at the bottom in the compressor 1.

Therefore, the refrigerating machine oil 6 does not disappear from the compressor 1, and the normal lubricating oil and the sealing function are maintained.

In the refrigerant circulation system configured as described above, a refrigerant mainly containing hydrocarbon is used as the refrigerant, and the refrigerating machine oil is alkylbenzene, polyalphaolefin, paraffinic mineral oil, or naphthenic mineral oil.
Since oil or chlorinated paraffin or the like as a main component can be used, the level of hygroscopicity of the refrigerating machine oil and the strength of the electric insulator are maintained at substantially the same level as those of the mineral oil in the conventional refrigerant circulation system. Also, the present invention has a saturated water content of 300 pp.
M or less refrigeration oil is used. CFC1 for moisture management during assembly and after-sales service of refrigerant cycle
It may be the same as the conventional one for two refrigerants.

It should be noted that a four-way valve is provided at a connecting portion where two connecting pipes arranged between the evaporator and the compressor and between the compressor and the condenser are combined, and the flow path of the four-way valve is switched. Accordingly, it is possible to provide control means for reversing the circulation direction of the refrigerant and reversing the functions of the evaporator and the condenser.

Since the present invention has the above configuration, this refrigerant circulation system mainly uses a refrigerant mainly composed of hydrofluorocarbon, is compatible with the liquid refrigerant on the condensation side, and has a compatibility with the liquid refrigerant. Since the refrigerating machine oil having incompatibility or weak compatibility is used, it is excellent in electric insulation and moisture resistance, and has good oil return to the compressor and high reliability.

Generally, in a compressor used in a refrigerant circulation system, at least 0.5% of a refrigerating machine oil in a weight ratio of the refrigerating machine oil to the circulating refrigerant is taken out into a refrigerant circuit. Therefore, when the refrigerating machine oil having a weight dissolution rate of 0.5% or less in the liquid refrigerant under the conditions of the condensing pressure and the condensing temperature is used, the rear end portion of the condenser pipe where the refrigerant is liquefied and the flow velocity is significantly reduced. In the vicinity, the refrigerating machine oil that cannot be dissolved in the liquid refrigerant stays, and the refrigerating machine oil in the compressor is depleted. In addition, when using a refrigerant having a high polarity such as hydrofluorocarbon, in order to ensure the solubility of the liquid refrigerant and the refrigerant oil so that the refrigerant oil does not stay in the liquid refrigerant near the rear end of the condenser pipe, the polarity of the refrigerant must be high. It is necessary to use high refrigerating machine oil, but refrigerating machine oil of high polarity that dissolves 7% or more has high hygroscopicity, and it is easy to bring a large amount of refrigerating machine oil into the refrigerant circuit.
There has been a risk of causing a decrease in the electrical insulation and a decrease in the chemical stability of the insulating material used for the refrigerant, the refrigerating machine oil, and the motor. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a refrigerating machine having a solubility of 0.5 to 7% by weight of a refrigerating machine oil in a liquid refrigerant under condensing pressure and condensing temperature conditions. Since the machine oil is used, the refrigerating machine oil taken out of the compressor into the refrigerant circuit can be reliably returned to the inside of the compressor, and since the refrigerating machine oil having low hygroscopicity is used, a highly reliable refrigerant circulation system is obtained. be able to.

The location where the refrigerating machine oil may accumulate is located in the middle of the condenser (usually closer to the outlet than half, but when the refrigerant has a low circulation amount, the liquid may be located at a location substantially upstream of the condenser. Only in some cases), the oil in the compressor is reduced, and when the piping from the condenser outlet to the throttle is long, oil in the compressor may be depleted. Was. The condensation pressure is determined by the condensation temperature condition and the refrigerant characteristics. The condensation temperature is determined by the ambient temperature at which the condenser of the refrigerant circulation system is placed, and the balance between the performance of the condenser (heat exchange efficiency) and the latent heat of the refrigerant. For example, the ambient temperature of a refrigerator is generally 0 to 45 ° C.
The condensation temperature at this time (depending on the performance of the condenser of the refrigerator) is 0 to 15 ° C. at an ambient temperature of 0 ° C. and 45 to 68 ° C. at an ambient temperature of 45 ° C. The condensation pressure at this time is determined by the characteristics of the refrigerant. For example, when R134a is used as the refrigerant, the condensation pressure is 1.96 kg / c at 0 ° C.
m ² G, 19.6 Kg / cm ² G at 68 ° C.

Whether the polarity is high or low is a relative matter. In this case, hydrofluorocarbons and third-generation refrigerants such as fluoroamines, fluoroethers,
Fluoropropane, fluoroethane, fluorosilane,
A refrigerant such as fluorosulfur has a higher polarity than CFC12 or HCFC22. As for the refrigerating machine oil, alkylbenzene, polyalphaolefin and the like have a lower polarity than the conventional ester oil and PAG. Generally, in terms of ease of dissolution, highly polar substances and low polar substances are easily dissolved. Accordingly, only a highly polar ester oil or PAG is dissolved in a relatively polar hydrofluorocarbon. Water is a substance having a relatively high polarity, and is easily dissolved in a similarly high-polarity ester oil or PAG. That is, oil that is easily dissolved in hydrofluorocarbon or the like has high hygroscopicity.
Conversely, oils that are difficult to dissolve in hydrofluorocarbons have low hygroscopicity. In addition, when using a refrigerant having a high polarity such as hydrofluorocarbon, in order to ensure the solubility of the liquid refrigerant and the refrigerant oil so that the refrigerant oil does not stay in the liquid refrigerant near the rear end of the condenser pipe, the polarity of the refrigerant must be high. It is necessary to use a high refrigerating machine oil, but a refrigerating machine oil with a high polarity that dissolves 7% or more has a high hygroscopicity, easily brings a large amount of the refrigerating machine oil into the refrigerant circuit, lowers the electrical insulation, reduces the refrigerant, the refrigerating machine oil and the motor. There is a possibility that the chemical stability of the insulating material used for the method may be deteriorated.

It should be noted that the polarity is said to have polarity when the centers of gravity of the positive and negative charges do not match in the molecule. When a specific chemical bond has a positive or negative charge, the bond is said to be polar. Generally means electrical polarity. When it has polarity, it tends to approach ions of the opposite sign or atoms of a polar bond, which affects the adsorption, the reaction rate, the dielectric constant, and the like.

Also, hydrofluorocarbon (HFC)
Alternatively, refrigerants such as fluoroamines, fluoroethers, fluoropropanes, fluoroethanes, fluorosilanes, and fluorosulfurs are promising alternatives to CFC12 and HCFC22, which have been targeted for reduction and decommissioning due to environmental issues. Generally, this hydrofluorocarbon has a higher polarity than CFC12 or HCHC22, whereas a refrigerator oil having low mutual solubility generally has a lower polarity. Therefore, refrigerating machine oil having a low mutual solubility with a highly polar refrigerant such as hydrofluorocarbon is unlikely to be adsorbed with highly polar water. As a result, the introduction of moisture into the refrigerant circulation system is suppressed, and the deterioration of electrical insulation and the degradation of hydrolyzable substances such as organic materials used in the compressor are unlikely to occur. The deterioration of the performance of the refrigerant circulation system due to accumulation in the section can be suppressed.

Further, hydrofluorocarbon (HF)
C) is effective as an alternative refrigerant to CFC12 and HCFC22, which are targeted for reduction and abolition due to environmental problems. However, since this hydrofluorocarbon does not contain chlorine atoms in the molecule, CFC12 having chlorine molecules and HC
As in FC22, a sliding portion placed under the boundary lubrication condition of a compressor forms a compound such as iron chloride on a metal surface and cannot expect an effect of increasing abrasion resistance. Furthermore, ester oils having high mutual solubility in hydrofluorocarbons have lower extreme pressure properties (high pressure viscosity index) than paraffinic oils or naphthenic oils used in refrigerant circulation systems using CFC12 or HCFC22 as a refrigerant. Sliding parts of the compressor are likely to be in boundary lubrication conditions. Therefore, particularly in a refrigerant circulation system using hydrofluorocarbon as a refrigerant, when an ester oil having mutual solubility is used as a refrigerating machine oil, there is a problem in abrasion resistance of a sliding portion of the compressor.

Although the present invention has been described with reference to an embodiment using a single or mixed refrigerant containing a hydrofluorocarbon as a main component, fluoroamines, fluoroethers, fluoropropanes, fluoroethanes, and so-called "third generation refrigerants" are used. Refrigerants such as fluorosilane and fluorosulfur are considered to be all refrigerants having high polarity when inferred from the molecular structure, and the same action and effect as hydrofluorocarbon can be expected.

Further, in this refrigerant circulation system, since refrigerating machine oil having low mutual solubility is used, the polarity of the refrigerating machine oil is low,
Since it is difficult to be adsorbed with highly polar water, it has an effect of suppressing a decrease in electrical insulation and a decrease in performance of the refrigerant circulation system due to accumulation of degraded substances in the throttle mechanism.

Further, in this refrigerant circulation system, since the refrigerating machine oil having low mutual solubility is used, the viscosity of the liquid supplied to the sliding portion is maintained at a high level, and the sliding portion is less likely to seize and has high reliability. A refrigerant circulation system can be obtained.

Embodiment 2 FIG. Hereinafter, Example 2 of the present invention will be described with reference to FIG.
It will be described based on. FIG. 3 shows an example of a system applied to, for example, a large-capacity air conditioner. 1 is a compressor for compressing refrigerant gas, 2 is a condenser for condensing high-pressure refrigerant gas discharged from the compressor 1, and 3 is a capillary tube. 4 is an evaporator, 8
Is a refrigerant reservoir accumulator having a refrigerant amount adjusting function, 6 is a refrigerating machine oil stored in the compressor 1 for lubricating sliding portions of the compressor 1 and sealing the compression chamber, and 5 is a refrigerant flow. It is a four-way valve that reverses.

Under the conditions of the evaporating pressure and the evaporating temperature, the refrigerating machine oil 6c has no or low solubility in the liquid refrigerant 7a, so that the refrigerating machine oil 6c forms a separation layer above the liquid refrigerant 7a. A plurality of oil return holes 82a, 82b, 82 having different heights from the accumulator lower end 8a are provided in an outlet pipe 81 in the accumulator 8 for guiding the refrigerant to the outside.
c and 82d are provided, and it is possible to accumulate surplus refrigerant according to the load condition of the device without accumulating a large amount of oil in the accumulator 8. The refrigerating machine oil 6c surely returns to the compressor 1.

Embodiment 3 FIG. Hereinafter, Example 3 of the present invention will be described with reference to FIG.
It will be described based on. FIG. 4 shows an example of a system applied to an air conditioner that is integrally attached to a window of a room, for example, inside and outside of a room, and a refrigerant pressurized by a compression mechanism 13 in the compressor 1 is discharged into a closed container 11. Later discharge pipe 1
4 to the outside. Therefore, the refrigerating machine oil 6 stored in the bottom of the compressor 1 is located in the high-pressure side refrigerant space, and the refrigerating machine oil contained in the discharged refrigerant gas is discharged from the high-pressure space, which is the space inside the closed casing 11, to the discharge pipe. Since the refrigerant gas has a specific gravity higher than that of the refrigerant gas in the space before it arrives at 14, it falls by its own weight. For this reason, the mixing ratio of the refrigerating machine oil in the refrigerant gas discharged from the discharge pipe 14 is extremely low, that is, the amount of the discharged oil is less than the dissolution rate of the refrigerating machine oil in the liquid refrigerant under condensing pressure conditions. Refrigeration oil discharged from the compressor surely returns to the compressor 1.

This refrigerant circulation system lubricates the compressor,
In addition to suppressing the refrigerating machine oil used for seals from flowing out to the condenser, throttling mechanism, and evaporator, the amount of discharged oil is small, so that the refrigerating machine oil that has flowed out can be reliably returned to the compressor. Does not reduce heat exchange efficiency.

That is, even when the bottom of the compressor in which the refrigerating machine oil is stored is arranged on the high pressure side, if the refrigerating machine oil having low mutual solubility is used, the change in viscosity due to the difference in the solubility of the refrigerant in the refrigerating machine oil may occur. The use of refrigerating machine oil of appropriate viscosity ensures both the reliability of the sliding part of the compressor when the ambient pressure where the refrigerating machine oil is placed at high pressure and the efficiency at low pressure. .

Embodiment 4 FIG. Hereinafter, Example 4 of the present invention will be described with reference to FIG.
It will be described based on. FIG. 5 shows an example of a system applied to, for example, a refrigerator. Reference numeral 9 denotes a check valve, which is provided between the compressor 1 and the evaporator 4. Since the refrigerant and the refrigerating machine oil are almost completely separated, the viscosity of the refrigerant alone becomes lower than the viscosity in which the refrigerant and the refrigerating machine oil are dissolved. Therefore, when the compressor 1 is stopped, the viscosity of the refrigerant alone is low, so that the fluidity is improved, and the liquid refrigerant 7 a separated in the lower layer of the refrigerating machine oil 6 is supplied to the compressor 1.
The amount of the refrigerant that tends to flow back to the evaporator 4 through the gap between the sliding portions in the inside increases, and as a result, the temperature of the evaporator 4 increases, and the power consumption of the refrigeration apparatus increases. Therefore, by providing the check valve 9 between the compressor 1 and the evaporator 4, it is possible to suppress the backflow of the refrigerant and suppress the temperature rise of the evaporator 4. Further, a check flow prevention function having a similar function may be provided instead of the check valve 9.

Embodiment 5 FIG. Hereinafter, Example 5 of the present invention will be described with reference to FIG.
It will be described based on. FIG. 6 shows an example of a system applied to, for example, an air conditioner dedicated to cooling. A refrigerant pressurized by a compression mechanism 13 in the compressor 1 is discharged into a closed container 11 and then discharged to an outside by a discharge pipe 14. Derived. The refrigerant gas inlet end 14a of the discharge pipe 14 is disposed at the center of the rotary fan 16 provided at the upper end of the rotor 12a of the electric motor 12, and the refrigerating machine oil having a large specific gravity is scattered to the outer peripheral portion by centrifugal force. . For this reason, the amount of oil discharged from the discharge pipe 16 is small, and the mixing ratio of the refrigerating machine oil in the refrigerant gas is extremely low, so that the refrigerating machine oil dissolution rate in the liquid refrigerant under the condensing pressure condition is significantly lower. The refrigerating machine oil returns to the compressor 1 without fail.

Embodiment 6 FIG. Hereinafter, Example 6 of the present invention will be described with reference to FIG.
It will be described based on. FIG. 7 shows an example of a system applied to, for example, a refrigerator or the like. When the refrigerant gas discharged from the compressor 1 is introduced into the middle of the oil separator 20 and guided to the pipe to the condenser 2, the oil separator The oil is separated by the inner net 83 and reaches the condenser 2. Refrigeration oil 6c separated by oil separator
Passes through the oil return capillary 21 derived from the oil separator,
Returning to the compressor 1 sucked into the suction pipe 15, the compressor 1
The lubrication and sealing functions are reliably maintained. Further, since the refrigerating machine oil contained in the refrigerant gas entering the condenser 2 is extremely low, the refrigerating machine oil is maintained at a dissolution rate of less than the refrigerating machine oil in the liquid refrigerant under the condensing pressure condition, and the refrigerating machine oil accumulates and remains upstream of the throttle mechanism. The system will not fail and the spilled refrigeration oil will surely return to the compressor. The discharge pipe 14
May be provided so as to surround the outlet in the oil separator 20.

The refrigerating machine oil 6 stored at the bottom of the compressor 1 is placed under the evaporating pressure and hardly dissolves in the liquid refrigerant together with the refrigerating machine oil 6c staying in the accumulator 8. However, since the specific weight of the liquid refrigerant 7a and the specific weight of the refrigerating machine oil 6c are substantially equal, they are mixed at a substantially uniform ratio. Therefore, even when a large amount of the liquid refrigerant 7 a accumulates in the accumulator 8, the oil return hole 8
2 ensures that the refrigerating machine oil is returned to the compressor 1. Even if the liquid refrigerant 7a returns to the inside of the compressor 1, since the stored refrigerant oil 6 and the liquid refrigerant 7a are mixed at a substantially uniform mixing ratio, the liquid refrigerant 7a flows through the oil absorption hole 17 provided at the lowermost end. Only the refrigerant 7a is not sucked up, and the refrigerating machine oil corresponding to the mixing ratio is reliably sucked up, and the lubrication and sealing functions are maintained.

Embodiment 7 FIG. Hereinafter, a seventh embodiment of the present invention will be described with reference to FIG.
It will be described based on. FIG. 8 shows an example of a system applied to, for example, an air conditioner. The refrigerating machine oil 6, for example, chlorofluorocarbon stored in the compressor 1 is placed under an evaporation pressure, and the refrigerating machine oil 6 c stays in the accumulator 8.
At the same time, it hardly dissolves in a liquid refrigerant such as HFC134a. However, relative to the specific weight of the liquid refrigerant 7a,
6c has a large specific weight of 1.9 times.
c forms a separation layer at the bottom. Therefore, even when a large amount of the liquid refrigerant 7 a accumulates in the accumulator 8, the refrigerating machine oil is reliably returned to the compressor 1 through the oil return hole 82 of the outlet pipe 81. Even if the liquid refrigerant 7a returns to the inside of the compressor 1, a separation layer is formed above the stored refrigerating machine oil 6, so that
Only the refrigerating machine oil is sucked up from the oil suction hole 17 provided at the lowermost end, and the lubrication and sealing functions of the compressor 1 are maintained.

In this case, a refrigerant mainly containing hydrofluorocarbon is used, and a refrigerating machine oil is mainly composed of chlorofluorocarbon polymer, perfluorocarbon polymer, perfluoroalkyl polyether, modified silicone or chlorinated aromatic. Is used.

Embodiment 8 FIG. Hereinafter, Embodiment 8 corresponding to the present invention will be described with reference to FIG. A refrigerant mixture of a plurality of refrigerants, and at least one of the constituent refrigerants is a flammable refrigerant, for example, HFC32 which is flammable as a single refrigerant.
And HFC125 and HFC1 which are nonflammable as sole refrigerants
In the case of using the refrigerant mixture of No. 34a, in the present invention, since a refrigerating machine oil which is insoluble or slightly soluble in the refrigerant is used, a large amount of the refrigerant does not dissolve in the refrigerating machine oil. Therefore, the refrigerant mixture ratio in the refrigeration cycle that is not dissolved in the refrigeration oil hardly changes with respect to the nonflammable mixture ratio before being filled in the refrigerant cycle,
There is no possibility that the mixture ratio becomes flammable. Therefore, even if the refrigerant in this state is released into the atmosphere due to some trouble or the like and there is an ignition heat source, there is no danger of ignition and fire.

FIG. 9 shows an example of a system applied to, for example, an air conditioner. The refrigerant sucked into the compressor 1 cools the electric motor 12 in the airtight container 11 and then is compressed in the compression mechanism 13 to form a four-way compressor. It is discharged to the condenser 2 through the valve 5. In this process, the refrigerating machine oil 6 stored at the bottom of the closed container 11 is structurally exposed to the refrigerant atmosphere sucked into the compressor 1, but the refrigerating machine oil 6 is insoluble or only slightly soluble. Since it does not have it, a large amount of refrigerant does not dissolve in the refrigerator oil 6.

Embodiment 9 FIG. Hereinafter, a ninth embodiment corresponding to the present invention will be described with reference to FIG. A refrigerant mixture of a plurality of refrigerants, and at least one of the constituent refrigerants is a flammable refrigerant, for example, HFC32 which is flammable as a single refrigerant.
And HFC125 and HFC1 which are nonflammable as sole refrigerants
In the case of using the refrigerant mixture of No. 34a, in the present invention, since a refrigerating machine oil which is insoluble or slightly soluble in the refrigerant is used, a large amount of the refrigerant does not dissolve in the refrigerating machine oil. Therefore, the refrigerant mixture ratio in the refrigeration cycle that is not dissolved in the refrigeration oil hardly changes with respect to the nonflammable mixture ratio before being filled in the refrigerant cycle,
There is no possibility that the mixture ratio becomes flammable. further,
Since the refrigerating machine oil used is a non-combustible substance, even if the refrigerant and the refrigerating machine oil are mist-like and are released into the air due to some trouble or the like and there is an ignition heat source, there is no risk of ignition and fire.

FIG. 10 shows an example of a system applied to, for example, an air conditioner. Refrigerant sucked into a compressor 1 is compressed in a compression mechanism 13 in a closed container 11 and then compressed by an electric motor 12.
Is cooled and discharged to the condenser 2 through the four-way valve 5. In this process, the refrigerating machine oil 6 stored at the bottom of the closed container 11
Is structurally exposed to the refrigerant atmosphere compressed by the compression mechanism 13, but since the refrigerating machine oil 6 has insolubility or only weak solubility, a large amount of refrigerant is dissolved in the refrigerating machine oil 6. Never do.

Embodiment 10 FIG. Hereinafter, a tenth embodiment corresponding to the present invention will be described with reference to FIG. If the refrigerating machine oil has low mutual solubility with the refrigerant and has a value smaller than the specific gravity of the liquid refrigerant measured at the same temperature and its saturated vapor pressure in the ambient temperature range of the refrigerant circulation system, When an azeotropic mixed refrigerant is used even if it is a refrigerant or a plurality of mixed refrigerants, the temperature of the evaporator 4 or the condenser 2 is slightly higher than the temperature of the compressor 1 when the compressor 1 is stopped. In this case, the refrigerant moves to the compressor 1 and stays in a large amount as the liquid refrigerant 7a at the bottom of the compressor. However, as shown in the present invention, when a non-azeotropic mixed refrigerant is used as the refrigerant,
Since the constituent refrigerant having a low boiling point in the refrigerant evaporates first, the constituent refrigerant in the refrigerant to which the refrigerating machine oil in the compressor 1 is exposed is higher in boiling point than the liquid refrigerant stored in the evaporator 4 and the condenser 2. Therefore, even if the temperature of the evaporator 4 or the condenser 2 is slightly higher than the temperature of the compressor 1, the refrigerant does not move to the compressor 1 side. Therefore, even at the time of startup after a long-term stop, the amount of liquid refrigerant 7a staying at the bottom of the compressor is suppressed, and the time during which the liquid refrigerant 7a is supplied to the sliding portion of the compressor 1 and the lubrication effect is reduced can be suppressed. Here, the term “azeotropic refrigerant” means that the condition that the vapor composition and the liquid composition of the refrigerant are the same is at least one within the pressure and temperature range used.
A dot refers to something that exists. On the other hand, the non-azeotropic refrigerant mixture means that the conditions under which the vapor composition and liquid composition of the refrigerant are the same are not within the pressure and temperature ranges used.

Incidentally, the mutual solubility of the refrigerating machine oil and the refrigerant is generally determined in accordance with JIS K2211 Appendix 3 under “Method of Testing Compatibility with Refrigerant”, “Take sample oil and refrigerant in a test tube and place at room temperature or in a hot water bath. In the test tube, cool the sample oil and refrigerant to make it evenly transparent.Next, cool the test tube, and determine the temperature at which the solution separates into two layers or the whole solution becomes milky. The two-layer separation temperature at the oil content (percentage of the sample oil in the sample oil / refrigerant mixed solution) is used to evaluate the compatibility of the refrigerating machine oil with the refrigerant. " That is, the oil having high mutual solubility is an oil having a low two-layer separation temperature, and a refrigerating machine oil conventionally used in a refrigerant circulation system using a refrigerant containing hydrofluorocarbon as a main component is represented by an ester oil. As can be seen, at least under the conditions of the condensing pressure and the condensing temperature, there was compatibility under all the mixing ratios of the refrigerant and the refrigerating machine oil. Further, the oil having a low mutual solubility is an oil having a high two-layer separation temperature,
As shown in the present invention, at least a certain mixing of the refrigerant and the refrigerating machine oil at the condensing pressure and the condensing temperature conditions, as represented by a hard alkylbenzene oil used in a refrigerant circulation system using a refrigerant whose main component is hydrofluorocarbon. There is no compatibility below the ratio. That is, although the maximum two-layer separation temperature (UCST) of the refrigerant and the refrigerating machine oil is equal to or higher than the condensing temperature, there is compatibility in the oil fraction at which the weight mixing ratio is 0.5 to 7% (depending on the condensing temperature) or lower. .

An embodiment will be described with reference to FIG. FIG. 12 shows an HFC known as a non-azeotropic refrigerant mixture.
32, a mixed refrigerant of HFC125 and HFC134a and a refrigerant circulating system using a mixed refrigerant of HFC32 and HFC125 known as an azeotropic refrigerant, the transfer rate of the refrigerant sealed in the refrigerant circulating system to the compressor is reduced by the refrigerant circulating rate. It shows a state that changes as the system stop time elapses. This is because the boiling point of HFC32 is-
54.8 ° C, boiling point of HFC125 is -48.6 ° C,
HFC134a has a boiling point of −26.2 ° C. and HFC3
2. Since the boiling point of HFC125 is far lower than that of HFC134a, the composition in the refrigerant circuit is higher than that of the liquid refrigerant.
C32 and HFC125 increase. As a result, the gas refrigerant in contact with the refrigerating machine oil in the compressor has a relatively low boiling point and is hardly liquefied, so that the transfer amount is limited. Therefore, if a non-azeotropic mixed refrigerant is used, the mutual solubility is low, and even when using a refrigerating machine oil having a lower specific gravity than the liquid refrigerant, the amount of the refrigerant transferred to the compressor is small. Thus, the amount of liquid refrigerant supplied to the sliding part of the compressor during the start-up after the long-term stoppage of the refrigerant circulation system can reduce the time during which the lubrication characteristics are reduced.

The transition rate indicates the following. Transfer rate = (amount of refrigerant transferred to the compressor) / (amount of refrigerant enclosed in the refrigerant circulation system) × 100 [%] The force for promoting the transfer is Δp = (pressure of the liquid refrigerant reservoir in the refrigerant circuit) − (Pressure in the pressure machine) It is assumed that this Δp exists. Here, the pressure is determined by the refrigerant characteristics and the temperature. In the case of a single or azeotropic refrigerant, Δt = (temperature of the liquid refrigerant reservoir in the refrigerant circuit) − (compressor temperature) The greater the Δt, the easier the transition. Even when Δt = 0, the transition is made when a refrigerating machine oil having strong mutual solubility is used.
Therefore, there is no mutual solubility and if Δt = 0, there is no transition. If Δt> 0 for a single or azeotropic refrigerant, the transition starts, and finally all the liquid refrigerant transitions to the low temperature side. In the non-azeotropic mixed refrigerant, even if Δt> 0, the composition of the gas and the liquid is different, so that the amount of the refrigerant finally transferred differs depending on the magnitude of Δt. This amount is determined by the difference between the composition of the gas and the liquid, and the above-mentioned difference in boiling point explains this. The difference between the composition of the gas and the liquid is determined by the type of the mixed refrigerant, the mixing ratio,
It is affected by the liquid-gas ratio (that is, temperature and pressure), temperature distribution, and solubility of refrigeration oil.

The following is an example of a non-azeotropic refrigerant mixture of HFC32 and HFC32.
The mixed refrigerant of FC134a will be described with reference to FIG. It is assumed that the two connected containers are under an atmosphere of -2.5 ° C. HFC32: HFC134a = 2 in one container
If there is a liquid refrigerant of 5: 75: wt% (assuming a liquid refrigerant reservoir in the refrigerant circuit), the gas composition of the other connected (assuming a compressor) is HFC32: HFC134a = 46:
It is 54 wt%, and since both are equalized at 3.7 Kg / cm ² G, the transfer of the refrigerant does not occur. From this state, the temperature of only the gas side container, that is, the side corresponding to the compressor is set to -2.
Reduce from 5 ° C to -7.5 ° C. If this refrigerant is a single refrigerant or an azeotropic refrigerant mixture, the transition on the low-temperature side is always low, so that the transition is performed continuously, and finally, all the liquid refrigerant is transitioned. However, since it is non-azeotropic, even if all the liquid refrigerant does not move, a part of the gas refrigerant on the compressor side is liquefied, and the liquid phase is HFC32: HFC134a = 41: 5 as shown in the figure below.
9 wt%, gas phase is HFC32: HFC134a = 6
3: In the state of 37% by weight, a state of equalization with the high-temperature side container can be achieved, so that no further transfer of the refrigerant occurs. Although migration by diffusion in the gas phase is also conceivable, the diffusion rate of the gas phase is generally very slow and does not pose a practical problem.

As described above, the transition is improved irrespective of the refrigeration oil as long as a non-azeotropic refrigerant mixture is used. However, the solubility of the refrigerating machine oil is also involved in the transfer, and the transfer can be further suppressed by using an oil having no mutual solubility.
Heavy oils and light oils do not have an advantage in terms of migration, but oils that do not have mutual solubility, especially light oils, have a great effect on securing reliability. -Oil with no mutual solubility + single or azeotropic refrigerant: Δt>
At 0, all liquid refrigerant is transferred. (It does not shift when Δt = 0) ・ Insoluble oil + non-azeotropic refrigerant: Δt even when Δt> 0
Is smaller, all liquid refrigerant does not migrate. Further, the amount of the refrigerant transferred from the mutually soluble oil is further suppressed.

In this case, the refrigerating machine oil may be a chlorofluorocarbon polymer or a perfluorocarbon polymer or a perfluoroalkyl polyether or a modified silicone oil.
A substance containing a cone or chlorinated aromatic as a main component is used.

In the above description, HFC32, HFC
125, HFC134a mixed refrigerant is shown. This is a non-azeotropic refrigerant mixture of three kinds as an alternative refrigerant of HCFC22 mainly used for air conditioners, which is the target of reduction and decommissioning due to environmental problems. Are most powerful in terms of efficiency, capacity, pressure and safety. HF in this mixed refrigerant
By entering C32, efficiency and performance are improved as compared with the case where C32 is not inserted. Although HFC32 is flammable by itself, it can be safely used because it is practically nonflammable at a certain mixing ratio with non-flammable HFC125 and HFC134a. In order to ensure a margin in terms of safety, the ratio of the HFC 32 may be reduced, but the efficiency tends to decrease accordingly. Therefore, under the same margin in terms of safety, the ratio of the flammable HFC 32 can be increased by using the immiscible oil as compared with the case using the compatible oil, and an efficient refrigerant can be used. Such a system is a technology corresponding to an alternative refrigerant to the HCFC 22 used in an air conditioner.
For example, the flammable refrigerant H is similarly used as a substitute refrigerant for the refrigerant R502 used in a refrigeration / refrigeration system used in a refrigerator.
Similarly, a mixed refrigerant (azeotropic) containing FC143a may be used. As for the non-combustibility of refrigeration oil,
For example, it can be distinguished by the presence or absence of a flash point defined in the flash point measurement method of JIS K2265.

The specific gravity of the oil in the above description is compared with
In the case of the mixed refrigerant, the specific gravity is the liquid refrigerant specific gravity in the composition of the mixed refrigerant in the refrigeration circuit. In addition, an azeotropic refrigerant exists even in a refrigerant containing a combustible refrigerant. For example, two types of mixed refrigerants of HFC143a and HFC125 including the combustible refrigerant HFC143a have close boiling points to each other and are azeotropic refrigerants. (HFC143
boiling point of a: -47.7 ° C, boiling point of HFC125: -4
8.1 ° C.) The non-azeotropic refrigerant is one in which the conditions under which the vapor composition and liquid composition of the refrigerant are the same are not within the pressure and temperature ranges used. In addition, CST (Critical Solub)
(ILITY TEMPERATURE) is JIS K2
At the two-layer separation temperature itself shown in 211 (P106), the test method shown in JIS K2211 claims "the oil content is in the range of 5 to 60% by mass".
This is because it generally has a maximum value in this range. This maximum value is referred to as UCST (Uppermost Crit
cal Solvity Temperatur
e).

In this refrigerant circulation system, since the refrigerant uses a non-azeotropic mixed refrigerant, the refrigeration oil is a liquid refrigerant measured at the same temperature and its saturated vapor pressure in the ambient temperature range of the refrigerant circulation system. Even when a material having a value smaller than the specific gravity is used, there is an effect that, at the time of startup after a long-term stop, the time during which the liquid refrigerant is supplied to the sliding portion of the compressor and the lubrication effect is reduced can be suppressed.

Further, since the saturated water content of the refrigerating machine oil is suppressed, the same or higher quality can be ensured by the same water management as the conventional one. In addition, the saturated water content was determined by using a refrigerator oil at a temperature of 30 ° C.
The sample was left in the air at a temperature of 85 ° C. and a humidity of 85 RH%, and the time-dependent change of the water content in the oil was measured.

Although the refrigerating machine oil of the above embodiment satisfies the performance required as a refrigerating machine oil without using additives, it uses a hindered phenol-based, amine-based or sulfur-based antioxidant such as 2 , 6-Di-t-butyl-4-
Methylphenol, 4,4'-methylenebis (2,6-
Di-t-butylphenol), 2,2′-thiobis (4
-Methyl-6-t-butylphenol), trimethyldihydroquinone, p, p'-dioctyldiphenylamine, 3,7-dioctylphenothiazine, alkylphenothiazine-1-carboxylate, phenyl-2-
0.2 to 5% by weight of naphthylamine, 2,6-di-t-butyl-2-dimethyl-p-cresol, 5-ethyl-10,10'-diphenylphenazaline, alkyl disulfide, etc., extreme pressure Agent, anti-wear agent, phosphate ester, phosphite ester, alkyl or aryl phosphorothionate, halogenated hydrocarbon, halogenated carboxylic acid, metal dialkyl or diaryldithiophosphate, metal dialkyldithiocarbamate, oil-soluble 1 to 30% by weight of a molybdenum sulfide-containing compound,
Additives such as 0.2 to 5% by weight of an epoxy compound as a thermal stability improver and 0.001 to 0.1% by weight of a dimethylpolysiloxane or a metal carboxylate as an antifoaming agent, alone or in combination. By doing so, the performance of the refrigerating machine oil such as abrasion resistance, load resistance and thermal stability can be further improved.

Since the present invention has the above configuration, this refrigerant circulation system mainly uses a refrigerant mainly composed of hydrofluorocarbon, has low compatibility with the liquid refrigerant on the condensation side, and Since a refrigerating machine oil having incompatibility or weak compatibility on the side is used, it is excellent in electric insulation and moisture resistance, and has good oil return to the compressor and high reliability.

In this refrigerant circulation system, a plurality of oil return holes are provided in the refrigerant outlet pipe from the accumulator, so that a large amount of oil does not accumulate in the accumulator.
Refrigerator oil can be reliably returned to the compressor, and excess refrigerant can be accumulated according to the load status of the device.

Further, in this refrigerant circulation system, since the refrigerating machine oil of the compressor is arranged in the high-pressure side refrigerant space, the mixing ratio of the refrigerating machine oil mixed with the discharge gas and flowing out to the system is suppressed, so that the reliability and the heat efficiency are improved. A system with high exchange efficiency can be obtained.

Further, in this refrigerant circulation system, a backflow prevention mechanism from the compressor to the evaporator is provided between the evaporator and the compressor. Therefore, when the compressor is stopped, gas leaking from the high pressure side is sucked. It is possible to prevent the temperature of the evaporator or the like from rising along the pipe by reaching the evaporator, thereby reducing the power consumption of the apparatus. In this case, a plurality of oil return holes can be provided in the refrigerant outlet pipe from the accumulator to reliably return the oil.

The refrigerant circulation system suppresses the mixing ratio of the refrigerating machine oil in the discharge gas discharged from the compressor and ensures the return of the refrigerating machine oil flowing out to the system. Become. Further, by combining a configuration in which a plurality of oil return holes are provided in the refrigerant outlet pipe from the accumulator, more reliable oil return is possible.

In this refrigerant circulation system, an oil separator is provided on the discharge side of the compressor, and the mixing ratio of the refrigerating machine oil mixed with the discharge gas and flowing out to the system is suppressed, so that the reliability and the heat exchange efficiency are high. A good system is obtained. It is more effective to combine this configuration with the other oil return measures described above.

When an on-off valve is provided between the evaporator and the compressor, the refrigerant circulation system includes a control means for closing the on-off valve when the compressor is stopped. The on-off valve prevents the compressor from flowing into the compressor, thereby preventing problems such as shaft seizure caused by lubrication oil in the compressor.

This refrigerant circulation system mainly uses a refrigerant mainly composed of hydrofluorocarbon, uses a refrigerating machine oil that is incompatible or weakly compatible with the liquid refrigerant on the evaporation side, and has a specific ratio of the refrigerating machine oil. When a material having a weight approximately equal to the specific weight of the liquid refrigerant is used, the refrigerant has excellent electrical insulation and moisture resistance, has good oil return to the compressor, and has high reliability.

This refrigerant circulation system mainly uses a refrigerant mainly composed of hydrofluorocarbon, uses a refrigerating machine oil that is incompatible or weakly compatible with the liquid refrigerant on the evaporation side, and has a specific ratio of the refrigerating machine oil. Since the weight used is larger than the specific weight of the liquid refrigerant, the sealing function and lubrication function of the compressor are remarkably stabilized, and the electrical insulation and moisture resistance are excellent, and the leakage of the refrigerating machine oil to the system is small, It has good oil return properties and high reliability.

According to the present invention, the molecules of hydrofluorocarbon are composed of hydrogen (H), carbon (C) and fluorine (F) atoms. As the atoms, atoms having at least the atomic weight of fluorine are required, but in general, a substance composed of a substance having a higher atomic weight is more expensive.
A light refrigerating machine oil as in the present invention can be realized at a low cost because it may be a substance composed of atoms such as hydrogen, carbon, and oxygen.

When a refrigerating machine oil having a low mutual solubility is used, the refrigerating machine oil or the refrigerant in contact with the refrigerating machine oil can reach the saturation temperature of the refrigerant at the atmospheric pressure where the refrigerating machine oil is placed. Low dissolution of refrigerant in machine oil. Therefore, the viscosity of the liquid supplied to the sliding portion is maintained at a high level, and seizure of the sliding portion hardly occurs.

In the case of using a refrigerating machine oil having low mutual solubility, the amount of the refrigerant contained in the oil leaking to the suction side of the compression chamber at the oil seal portion is small, so that the refrigerant re-expands and re-compresses in the compression process. The loss due to this is small, and the decrease in efficiency can be suppressed.

If a non-azeotropic mixed refrigerant is used as the refrigerant, the refrigerating machine oil has a specific gravity lower than the specific gravity of the liquid refrigerant measured at the same temperature and its saturated vapor pressure at least in the ambient temperature range of the refrigerant circulation system. Even when the compressor takes a value, when the compressor is stopped, the refrigerant moves from the evaporator or the condenser to the compressor, and the amount of liquid refrigerant remaining at the bottom of the compressor is suppressed. In the above, the time during which the liquid refrigerant is supplied to the sliding portion of the compressor and the lubricating effect is reduced can be suppressed.

This refrigerant circulation system is used to lubricate the compressor,
In addition to suppressing the refrigerating machine oil used for seals from flowing out to the condenser, throttling mechanism, and evaporator, the amount of discharged oil is small, so that the refrigerating machine oil that has flowed out can be reliably returned to the compressor. Does not reduce heat exchange efficiency.

This refrigerant circulation system is used to lubricate the compressor,
In addition to suppressing the refrigerating machine oil used for seals from flowing out to the condenser, throttle mechanism and evaporator, the refrigerating machine oil that has flowed out can be reliably returned to the compressor, reducing the heat exchange efficiency of the condenser and evaporator. Do not let.

The refrigerant circulation system of the present invention can reliably return the refrigerating machine oil used for lubrication and sealing of the compressor to the condenser, the throttle mechanism, and the evaporator, to the compressor. And does not reduce the heat exchange efficiency of the evaporator.

The refrigerant circulation system does not ignite even if the refrigerant is released into the atmosphere due to some trouble or the like and there is an ignition heat source, thereby avoiding the danger of causing a fire. Further, this refrigerant circulation system makes the refrigerating machine oil non-combustible and does not ignite even if it is discharged into the atmosphere in the form of mist.

Further, in this refrigerant circulation system, since a large amount of refrigerant is not dissolved in the refrigerating machine oil, a refrigerant mixture of a plurality of refrigerants and at least one of the constituent refrigerants is a flammable refrigerant. At this time, the refrigerant mixture ratio in the refrigeration circulation cycle hardly changes from the mixture ratio before being enclosed in the refrigerant circulation cycle in which non-combustibility has been confirmed. The ratio does not change and nonflammability can be maintained, so that the refrigerant in this state is released to the atmosphere due to some kind of trouble and does not ignite even if there is an ignition heat source, and there is no risk of causing a fire etc. A highly efficient refrigerant circulation cycle can be obtained.

In this refrigerant circulation system, since a large amount of refrigerant is not dissolved in the refrigerating machine oil, a refrigerant mixture of a plurality of refrigerants and at least one of the constituent refrigerants is a flammable refrigerant. At this time, the refrigerant mixture ratio in the refrigeration circulation cycle hardly changes from the mixture ratio before being enclosed in the refrigerant circulation cycle in which non-combustibility has been confirmed. Incombustibility can be maintained without changing the ratio, and the refrigerating machine oil used is incombustible, so even if a refrigerant in this state is released to the atmosphere due to some trouble etc. and there is an ignition heat source, it will ignite Therefore, it is possible to obtain a highly safe refrigerant circulation cycle that does not cause fire or the like.

Also, hydrofluorocarbon (HFC)
Is a promising alternative to CFC12 and HCFC22, which are subject to reduction and decommissioning plans due to environmental issues. However, since this hydrofluorocarbon does not contain chlorine atoms in the molecule, CFC12 or HCFC with chlorine molecules
As in the case of No. 22, the effect of increasing the wear resistance by forming a compound such as iron chloride on the metal surface by the sliding portion placed under the boundary lubrication condition of the compressor cannot be expected. Furthermore, ester oils having high mutual solubility in hydrofluorocarbons have lower extreme pressure properties (high pressure viscosity index) than paraffinic oils or naphthenic oils used in refrigerant circulation systems using CFC12 or HCFC22 as a refrigerant. Sliding parts of the compressor are likely to be in boundary lubrication conditions. Therefore, particularly in a refrigerant circulation system using hydrofluorocarbon as a refrigerant, when a mutually soluble ester oil is used as a refrigerating machine oil, there is a problem in terms of abrasion resistance of a sliding portion of a compressor. The use of compatible oils eliminates this problem.

[0101]

According to the present invention having the above-described structure, there is an effect that a highly reliable system having excellent electrical insulation and moisture resistance can be obtained.

[0102]

Since the present invention has the above-described structure, there is an effect that a highly safe refrigerant circulation cycle which does not cause a fire or the like can be obtained.

Since the present invention has the above-described configuration, there is an effect that a highly reliable system can be obtained without any abnormality in the sliding portion of the compressor at the time of startup after a long-term stop.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a refrigerant circulation system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a weight dissolution rate of refrigerating machine oil in a liquid refrigerant according to an embodiment of the present invention.

FIG. 3 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 4 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 6 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 7 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 8 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 9 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 10 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 11 is a configuration diagram of a refrigerant circulation system according to another embodiment of the present invention.

FIG. 12 is a characteristic diagram of a transfer rate of a mixed refrigerant to a compressor.

FIG. 13 is an explanatory diagram of refrigerant transfer in a mixed refrigerant.

FIG. 14 is a configuration diagram of a conventional refrigerant circulation system.

FIG. 15 is a configuration diagram of a refrigerant circulation system according to another example of the related art.

FIG. 16 is a diagram showing a weight dissolution rate of a refrigerant in refrigerating machine oil according to another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Throttle mechanism 4 Evaporator 5 Four-way valve 6 Refrigerator oil 7 Refrigerant 8 Accumulator 9 Check valve 10 Open / close valve 11 Sealed container 12 Electric motor 13 Compression mechanism 14 Discharge pipe 15 Suction pipe 16 Rotary fan 17 Oil absorption hole 20 Oil separator 21 Oil return thin tube 81 Accumulator outlet pipe 82 Oil return hole of accumulator outlet pipe

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C10N 40:30 (72) Inventor Takuho Hirahara 3-18-1, Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka Works ( 72) Inventor Susumu Kawaguchi 3-18-1, Oka, Shizuoka-shi, Mitsubishi Electric Corporation Shizuoka Works (72) Inventor Tatsuaki Shimizu 3-1-1, Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka Works (72) Inventor Kawa-Saki ▼ Katsuyuki 3-181, Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka Works (72) Inventor Noboru Masuda 3-1-1, Oka, Shizuoka City Mitsubishi Electric Corporation Shizuoka Works (72 Inventor Shinobu Ogasawara 3-18-1, Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka Works (72) Inventor Hiroshige Konishi 3-1-1, Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka In-house (72) Inventor Maruyama, etc. 3-181-1, Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka Works (72) Inventor Satoshi Suzuki 3-1-1, Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka Works ( 72) Inventor Yasuyuki Akahori 3-18-1 Oka, Shizuoka-shi Mitsubishi Electric Corporation Shizuoka Works (56) References JP-A-2-37256 (JP, A) JP-A-1-120065 (JP, U) 55-96373 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F25B 1/00-13/00 C10M 105/08 C10M 105/50 C10M 107/38 C10N 40: 30

Claims (5)

(57) [Claims] 1. A method comprising a hydrofluorocarbon as a main component .
With that refrigerant, the gaseous refrigerant including a liquid refrigerant is sucked into the gas refrigerant or a part, a compressor for discharging a high pressure gas refrigerant, a diaphragm mechanism for reducing the pressure of the liquid refrigerant containing gaseous refrigerant to liquid refrigerant or a part A condenser for condensing the high-pressure gas refrigerant discharged from the compressor and an evaporator for evaporating the liquid refrigerant or the gas-liquid two-phase refrigerant discharged from the throttle mechanism to circulate the refrigerant to form a refrigerant circulation system. In the above, provided at least a part of the compressor is provided in the system or stored in a separate tank or the like and is exposed to the refrigerant at least in part , and includes a refrigerating machine oil that performs a lubrication or sealing function.
The refrigerating machine oil is insoluble or weakly soluble in refrigerant.
The refrigerant has a plurality of refrigerants including flammable
A refrigerant circulation system using a mixed refrigerant of a medium . 2. A high-pressure gaseous refrigerant using a refrigerant having fluoroamine, fluoroether, fluoropropane, fluoroethane, fluorosilane or fluorosulfur as a main component, sucking a gaseous refrigerant or a gaseous refrigerant partially containing a liquid refrigerant. A compressor that discharges the liquid refrigerant, a throttle mechanism that decompresses the liquid refrigerant or a liquid refrigerant that partially contains a gas refrigerant, a condenser that condenses the high-pressure gas refrigerant discharged from the compressor, and a liquid that flows out of the throttle mechanism. In a refrigerant circulating system in which a refrigerant or an evaporator for evaporating a gas-liquid two-phase refrigerant is connected to circulate the refrigerant, at least a part of the refrigerant stored in the compressor or a separate tank or the like provided in the system is the A refrigerating machine oil which is exposed to a refrigerant and performs a lubrication or sealing function, etc .;
Freezing machine oil has insolubility or weak solubility
The refrigerant uses a mixed refrigerant of a plurality of refrigerants containing flammability
Refrigerant circulation system, characterized in that the. 3. A refrigerant comprising a plurality of refrigerants mixed with a non-azeotropic refrigerant.
3. The refrigerant according to claim 1, wherein the refrigerant is a medium.
Circulation system. 4. A gas refrigerant or a gas refrigerant partially containing a liquid refrigerant.
A compressor that sucks a body refrigerant and discharges it as a high-pressure gas refrigerant
And decompress the liquid refrigerant or liquid refrigerant partially containing gas refrigerant
And a high-pressure gas cooler discharged from the compressor
The condenser that condenses the medium and the liquid refrigerant that comes out of the throttle mechanism also
Properly is ligated and steam Hatsuki evaporating the gas-liquid two-phase refrigerant, the
A refrigerant circulation system for circulating the refrigerant by
Inside the compressor or in a separate tank provided in the
Stores refrigerating machine oil to perform lubrication or sealing functions.
Part or all of the refrigerating machine oil
In the structure to be exposed,
Refrigeration oil is considered to be insoluble or weakly soluble.
In addition, at least one of the constituent refrigerants is flammable.
It is characterized by using a mixed refrigerant of a plurality of refrigerants
Refrigerant circulation system. 5. Use of a non-combustible refrigerating machine oil.
The refrigerant circulation system according to claim 3 or 4, wherein
M