JP6736019B2 - Refrigerator, method for manufacturing refrigerator, and method for improving COP - Google Patents

Description

The present invention relates to a refrigerator, a refrigerator manufacturing method, and a COP improving method.

The refrigerator includes a refrigerant circulation system including a compressor, a condenser, an expansion mechanism, an evaporator, and the like. In the refrigerant circulation system, the phenomenon that heat is taken from the surroundings when the liquid is vaporized is used, and the vaporized refrigerant is compressed and heated by the compressor, and the refrigerant is liquefied by heat radiation condensation in the condenser. The cycle including decompression expansion of the above and vaporization of the refrigerant in the evaporator is repeated.

A coefficient of performance (COP) is often used as an index for evaluating the performance of such a refrigerator. COP represents a ratio (cooling capacity/consumed energy) of cooling capacity (also called refrigerating capacity) to energy consumed when operating the refrigerant circulation system. In recent years, further improvement of the COP of the refrigerator has been desired, and for example, Patent Literature 1 discloses an expander-integrated compressor capable of improving the COP of the refrigerator.

JP, 2005-94259, A

An object of the present invention is to provide a refrigerator having excellent COP, a method for manufacturing the same, and a method for improving COP.

The present invention is a refrigerator that includes a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, and is a refrigerator in which refrigerant and refrigeration oil are filled in the refrigerant circulation system. A working fluid composed of refrigerating machine oil provides a refrigerating machine showing a refrigerant dissolution viscosity of ^{2 to} 4 mm2/s under conditions of a temperature of 80°C and an absolute pressure of 3.4 MPa.

In this refrigerating machine, the refrigerant and refrigerating machine oil with which the refrigerant circulating system is filled exhibit a specific refrigerant melt viscosity as a working fluid, whereby the COP can be improved. That is, according to the study by the present inventors, if the refrigerant dissolution viscosity of the working fluid is too low, the refrigerating capacity or the cooling capacity will decrease due to the deterioration of the sealability, while the working fluid melts the refrigerant. It has been found that if the viscosity is too high, energy consumption increases due to an increase in stirring resistance or resistance at the time of starting the refrigerator, and the refrigerating capacity or the cooling capacity decreases. Then, the inventors of the present invention suppress the consumption energy and reduce the refrigerating capacity or the cooling capacity by using a working fluid having a refrigerant dissolution viscosity of ^{2 to} 4 mm ² /s under the conditions of a temperature of 80° C. and an absolute pressure of 3.4 MPa. It has been found that a balance with improvement can be secured and COP can be improved.

Further, the present invention is a method of manufacturing a refrigerator including a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, wherein the refrigerant circulation system is filled with a refrigerant and refrigerating machine oil. A working fluid comprising a refrigerant and refrigerating machine oil is provided, which has a step and exhibits a refrigerant dissolution viscosity of ^{2 to} 4 mm2/s under conditions of a temperature of 80°C and an absolute pressure of 3.4 MPa.

Further, the present invention includes a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, and improves the COP of a refrigerator in which the refrigerant circulation system is filled with a refrigerant and refrigerating machine oil. COP by using a working fluid having a refrigerant dissolution viscosity of ^{2 to} 4 mm ² /s under the conditions of a temperature of 80° C. and an absolute pressure of 3.4 MPa as a working fluid composed of a refrigerant and refrigerating machine oil. Provide a way to improve.

ADVANTAGE OF THE INVENTION According to this invention, the refrigerator excellent in COP, its manufacturing method, and the improvement method of COP can be provided.

It is a schematic diagram which shows one Embodiment of a refrigerator. It is a graph which shows an example of the relationship between a refrigerant|coolant melt viscosity and COP.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of a refrigerator. As shown in FIG. 1, a refrigerator 10 includes a compressor (refrigerant compressor) 1, a condenser (gas cooler) 2, an expansion mechanism 3 (capillary, expansion valve, etc.), and an evaporator (heat exchanger). At least a refrigerant circulation system 6 in which 4 and 4 are sequentially connected by a flow path 5 is provided.

In the refrigerant circulation system 6, first, the high-temperature (usually 70 to 120° C.) refrigerant discharged from the compressor 1 into the flow path 5 becomes a high-density fluid (supercritical fluid or the like) in the condenser 2. .. Subsequently, the refrigerant is liquefied by passing through the narrow flow path of the expansion mechanism 3, and further vaporized by the evaporator 4 to have a low temperature (usually −40 to 0° C.). The cooling by the refrigerator 10 uses a phenomenon that heat is taken from the surroundings when the refrigerant is vaporized in the evaporator 4.

In the compressor 1, a small amount of refrigerant and a large amount of refrigerating machine oil coexist under high temperature (usually 70 to 120° C.) conditions. The refrigerant discharged from the compressor 1 to the flow path 5 is in a gaseous state and contains a small amount (usually 1 to 10% by volume) of refrigerating machine oil as a mist. The refrigerant is dissolved (point a in FIG. 1).

In the condenser 2, the gaseous refrigerant is compressed into a high-density fluid, and a large amount of refrigerant and a small amount of refrigerating machine oil coexist under a relatively high temperature (usually 50 to 70° C.) condition (FIG. 1). Middle point b). Further, a mixture of a large amount of refrigerant and a small amount of refrigerating machine oil is sequentially sent to the expansion mechanism 3 and the evaporator 4 and suddenly becomes a low temperature (usually -40 to 0° C.) (points c and d in FIG. 1), It is returned to the compressor 1 again.

Examples of the refrigerator 10 include an automobile air conditioner, a dehumidifier, a refrigerator, a refrigerating/freezing warehouse, a vending machine, a showcase, a cooling device in a chemical plant, a residential air conditioner, a package air conditioner, a hot water supply heat pump, and the like. Can be mentioned.

As described above, the refrigerant circulation system 6 is filled with the refrigerant and the refrigerating machine oil. The refrigerant and the refrigerating machine oil may be appropriately selected so that the working fluid including the refrigerant and the refrigerating machine oil exhibits a refrigerant dissolution viscosity of ^{2 to} 4 mm ² /s under the conditions of a temperature of 80° C. and an absolute pressure of 3.4 MPa.

As the refrigerant, a saturated fluorohydrocarbon (HFC) refrigerant, an unsaturated fluorohydrocarbon (HFO) refrigerant, a hydrocarbon refrigerant, a fluorine-containing ether-based refrigerant such as perfluoroethers, a bis(trifluoromethyl)sulfide refrigerant, Examples include trifluoroiodomethane refrigerants and natural refrigerants such as ammonia (R717) and carbon dioxide (R744).

The saturated fluorohydrocarbon refrigerant is preferably a saturated fluorohydrocarbon having 1 to 3 carbon atoms, and more preferably 1 to 2 carbon atoms. The saturated fluorohydrocarbon refrigerant is, for example, difluoromethane (R32), trifluoromethane (R23), pentafluoroethane (R125), 1,1,2,2-tetrafluoroethane (R134), 1,1,1, 2-tetrafluoroethane (R134a), 1,1,1-trifluoroethane (R143a), 1,1-difluoroethane (R152a), fluoroethane (R161), 1,1,1,2,3,3,3 -Heptafluoropropane (R227ea), 1,1,1,2,3,3-hexafluoropropane (R236ea), 1,1,1,3,3,3-hexafluoropropane (R236fa), 1,1, It may be any one of 1,3,3-pentafluoropropane (R245fa) and 1,1,1,3,3-pentafluorobutane (R365mfc), or a mixture of two or more thereof.

Examples of the saturated fluorohydrocarbon refrigerant include R32 alone; R23 alone; R134a alone; R125 alone; R134a/R32=60 to 80 mass%/40 to 20 mass% mixture; R32/R125=40 to 70 mass%/ 60 to 30 mass% mixture; R125/R143a=40 to 60 mass%/60 to 40 mass% mixture; R134a/R32/R125=60 mass%/30 mass%/10 mass% mixture; R134a/R32/ R125=40 to 70% by mass/15 to 35% by mass/5 to 40% by mass; R125/R134a/R143a=35 to 55% by mass/1 to 15% by mass/40 to 60% by mass. As a preferable example. More specifically, a mixture of R134a/R32=70/30% by mass; a mixture of R32/R125=60/40% by mass; a mixture of R32/R125=50/50% by mass (R410A); R32/R125=45 R55/55 mass% mixture (R410B); R125/R143a=50/50 mass% mixture (R507C); R32/R125/R134a=30/10/60 mass% mixture; R32/R125/R134a=23/25 /52 mass% mixture (R407C); R32/R125/R134a=25/15/60 mass% mixture (R407E); R125/R134a/R143a=44/4/52 mass% mixture (R404A) and the like are preferable. Used.

Examples of unsaturated fluorohydrocarbon refrigerants include fluoroethylene having a fluorine number of 3 and fluoropropene having a fluorine number of 3 to 5. The unsaturated fluorohydrocarbon refrigerants are, for example, 1,1,2-trifluoroethylene (HFO-1123), 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 1,3,3. ,3-Tetrafluoropropene (HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,2,3,3-tetrafluoropropene (HFO-1234ye), and 3,3. , 3-trifluoropropene (HFO-1243zf), or a mixture of two or more thereof.

Examples of the hydrocarbon refrigerant include hydrocarbons having 1 to 5 carbon atoms. The hydrocarbon refrigerant is, for example, one or two of methane, ethylene, ethane, propylene, propane (R290), cyclopropane, normal butane, isobutane, cyclobutane, methylcyclopropane, 2-methylbutane, and normal pentane. It may be a mixture of the above.

The refrigerant preferably contains difluoromethane (R32), more preferably difluoromethane (R32) and pentafluoroethane (R125), from the viewpoint of easily obtaining high-temperature and high-pressure conditions of 80° C. or higher and 3.4 MPa or higher. ing. The refrigerant may further contain the above-mentioned refrigerants in addition to difluoromethane or difluoromethane and pentafluoroethane. The refrigerant used with difluoromethane or difluoromethane and pentafluoroethane is preferably 1,1,1,2-tetrafluoroethane (R134a), 2,3,3,3-tetrafluoropropene (HFO1234yf), 1 , 3,3,3-tetrafluoropropene (HFO1234ze(E) or (Z)) or trifluoroethylene (HFO1123).

The content of the refrigerant used with difluoromethane or difluoromethane and pentafluoroethane may be, for example, 80% by mass or less, and preferably 30 to 60% by mass, based on the total amount of the refrigerant.

Among these, as the refrigerant, a mixed refrigerant (R407C) of R32, R125 and R134a having a mass ratio (R32/R125/R134a) of 23/25/52, and a mass ratio (R32/R125/HFO1234yf/R134a) are used. The mixed refrigerant (R449A) of R32, R125, HFO1234yf and R134a, which is 24.3/24.7/25.3/25.7, and the mass ratio (R32/R125/HFO1234yf/R134a/HFO1234ze(E)) are 26. A mixed refrigerant (R448A) of R26, R125, HFO1234yf, R134a, and HFO1234ze(E), which is /26/20/21/7, is preferably used.

The refrigerant more preferably consists of difluoromethane and pentafluoroethane. The mass ratio (R32/R125) of difluoromethane (R32) and pentafluoroethane (R125) in the refrigerant may be, for example, 40/60 to 70/30. Examples of such a refrigerant include a refrigerant having a mass ratio (R32/R125) of 60/40, a refrigerant having a mass ratio (R32/R125) of 50/50 (R410A), and a mass ratio (R32/R125) of 45. A refrigerant (R410B) of /55 is preferably used, and R410A is particularly preferably used.

The refrigerating machine oil may be a refrigerating machine oil having a refrigerant dissolution viscosity of 2 to 4 mm ² /s in a state (working fluid) mixed with a refrigerant at a temperature of 80° C. and an absolute pressure of 3.4 MPa. The refrigerating machine oil must be selected in consideration of the viscosity of the refrigerating machine oil itself and the fact that the compatibility (solubility) between the refrigerant and the refrigerating machine oil varies depending on the type of the refrigerating machine oil. That is, by selecting an appropriate refrigerating machine oil in terms of both the viscosity of the refrigerating machine oil itself and the compatibility (solubility) with the refrigerant, the refrigerant dissolving viscosity of the working fluid falls within the above range.

Kinematic viscosity at 40 ° C. of the refrigerating machine oil is preferably ^{2 mm} 2 / s or more, more preferably 10 mm ² / s or more, more preferably at 20 mm ² / s or more, and preferably not more than 125 mm ² / s, more preferably Is 100 mm ² /s or less, more preferably 80 mm ² /s or less.

The kinematic viscosity of the refrigerating machine oil at 100° C. is preferably 1 mm ² /s or more, more preferably 2 mm ² /s or more, further preferably 3 mm ² /s or more, and preferably 11 mm ² /s or less, more preferably Is 10 mm ² /s or less, more preferably 9 mm ² /s or less.

The kinematic viscosity in the present invention means the kinematic viscosity measured according to JIS K-2283:1993.

The viscosity reduction rate before and after the refrigerating machine oil is dissolved in the refrigerant (hereinafter, also simply referred to as “viscosity reduction rate”) is calculated according to the following equation (1).
Viscosity decrease rate (%)=(kinematic viscosity-refrigerant dissolution viscosity)/kinematic viscosity×100 (1)
In the formula (1), the kinematic viscosity means the kinematic viscosity (mm ² /s) of the refrigerating machine oil at 80° C., and the refrigerant dissolution viscosity is the working fluid temperature consisting of the refrigerant and the refrigerating machine oil at 80° C. and the absolute pressure of 3.4 MPa. Means the refrigerant dissolution viscosity (mm ² /s).

The larger the viscosity decrease rate, the more easily the refrigerant dissolves in the refrigerating machine oil, but if the refrigerating machine oil dissolves in the refrigerant too much, the lubricity tends to decrease, so the viscosity decreasing rate of the refrigerating machine oil is from the viewpoint of excellent lubricity. , Preferably 85% or less, more preferably 80% or less. The lower limit of the viscosity reduction rate of the refrigerating machine oil is not particularly limited, but the smaller the viscosity reduction rate, the more difficult the refrigerant is to dissolve in the refrigerating machine oil, so from the viewpoint of compatibility, 60% or more, 70% or more, or It may be 75% or more.

The pour point of the refrigerating machine oil may be preferably -10°C or lower, more preferably -20°C or lower. The pour point in the present invention means the pour point measured according to JIS K2269-1987.

The refrigerating machine oil having the above characteristics contains a lubricating base oil and, if necessary, an additive. The lubricating base oil may be, for example, a hydrocarbon oil or an oxygenated oil. Examples of hydrocarbon oils include mineral oils, olefin polymers, naphthalene compounds and alkylbenzenes. Examples of the oxygen-containing oil include ester oils such as monoester, diester, polyol ester and complex ester, and ether oils such as polyalkylene glycol, polyvinyl ether, polyphenyl ether and perfluoroether. The oxygen-containing oil preferably contains at least one selected from polyol ester, polyalkylene glycol and polyvinyl ether as a main component, and more preferably contains a polyol ester or polyvinyl ether as a main component. The content of the lubricating base oil may be 80% by mass or more, 90% by mass or more, or 95% by mass or more based on the total amount of the refrigerating machine oil.

Examples of additives include acid scavengers such as epoxy compounds and carbodiimide compounds, antioxidants such as phenol compounds and amine compounds, extreme pressure agents such as phosphorus compounds and sulfur compounds, oiliness agents such as ester compounds, and deodorizers such as silicone compounds. Examples thereof include foaming agents, metal deactivators such as benzotriazole compounds, antiwear agents such as phosphorus compounds, and viscosity index improvers such as poly(meth)acrylate compounds. The content of the additive may be 5% by mass or less or 2% by mass or less based on the total amount of the refrigerating machine oil.

The content of the refrigerating machine oil in the working fluid may be 1 to 500 parts by mass, or 2 to 400 parts by mass with respect to 100 parts by mass of the refrigerant.

The refrigerant dissolution viscosity at a working fluid temperature of 80° C. and an absolute pressure of 3.4 MPa is 2 to 4 mm ² /s, preferably ^{2 to} 3.9 mm ² /s, ^{2 to} 3.8 mm ² /s, 2 ^{3.6mm 2 /s,2.1~4mm 2 /s,2.1~3.9mm 2 /s,2.1~3.8mm 2} /s,2.1~3.6mm 2 / s, 2 ^{.2~4mm 2 /s,2.2~3.9mm 2 /s,2.2~3.8mm 2 /s,2.2~3.6mm 2} /s,2.4~4mm 2 / s, 2.4~3.9mm ² /s,2.4~3.8mm ² / s, or a 2.4~3.6mm ² / s.

The refrigerant dissolution viscosity of the working fluid is measured according to the following procedure. First, 100 g of refrigerating machine oil filled in the refrigerant circulation system 6 is placed in a 200 mL pressure-resistant container containing a vibrating viscometer, and the inside of the container is vacuum deaerated, and then a refrigerant is added to prepare a working fluid. At this time, the pressure of the refrigerant and the temperature of the pressure vessel are adjusted so that the temperature is 80° C. and the absolute pressure is 3.4 MPa. Then, the viscosity of the working fluid in the container is measured.

The refrigerator 10 is, for example, filled in the refrigerant circulation system 6 with a refrigerant and a refrigerating machine oil that have a working fluid temperature of 80° C. and a refrigerant dissolution viscosity of ^{2 to} 4 mm ² /s under an absolute pressure of 3.4 MPa. It is manufactured by a manufacturing method including a step (filling step). In the filling step, the refrigerant circulation system 6 may be filled with the refrigerant and the refrigerating machine oil separately. The steps other than the filling step may be the same as the known refrigerator manufacturing method.

In the refrigerator 10 described above, the refrigerant circulation system 6 is filled with the refrigerant and the refrigerating machine oil in which the working fluid has a refrigerant dissolution viscosity of ^{2 to} 4 mm ² /s under the conditions of a temperature of 80° C. and an absolute pressure of 3.4 MPa. By doing so, it is possible to secure a balance between suppression of energy consumption and improvement of refrigerating capacity or cooling capacity, and it is possible to improve COP. It becomes possible to improve COP.

Here, the COP of the refrigerator 10 is calculated according to the following equation (2). The COP of the refrigerator 10 can also be calculated according to the following formula (3).
COP=cooling capacity (cooling amount) [W]/energy consumption [W] (2)
COP=(h ₁ −h ₂ )×G/P (3)
In the formula (3), h ₁ represents an outlet enthalpy [J/kg] of the evaporator (heat exchanger) 4, and h ₂ represents an inlet enthalpy [J/kg] of the evaporator (heat exchanger) 4, G represents the mass flow rate [kg/s] of the refrigerant circulating in the refrigerant circulation system 6, and P represents the power (power consumption) [W] of the motor (not shown) that drives the refrigerant circulation system 6.

FIG. 2 shows the refrigerant dissolution viscosity of the working fluid and the COP of the refrigerator 10 when a mixed refrigerant containing difluoromethane (for example, R410A) is used as the refrigerant and a refrigerator oil having the above-mentioned preferable kinematic viscosity is used as the refrigerator oil. It is a graph which shows an example of the relationship of. As shown in FIG. 2, when the refrigerant dissolution viscosity of the working fluid is less than 2 mm ² /s, the refrigerating capacity or the cooling capacity is deteriorated due to the deterioration of the sealability and the desired COP cannot be obtained. On the other hand, if the refrigerant dissolution viscosity of the working fluid exceeds 4 mm ² /s, energy consumption will increase due to an increase in stirring resistance or resistance at the time of starting the refrigerator, and the refrigerating capacity or cooling capacity will decrease. Therefore, the desired COP cannot be obtained. Therefore, the working fluid composed of the refrigerant and the refrigerating machine oil filled in the refrigerant circulation system 6 needs to exhibit a refrigerant dissolution viscosity of ^{2 to} 4 mm ² /s under the conditions of a temperature of 80° C. and an absolute pressure of 3.4 MPa. In this case, both suppression of energy consumption and improvement of refrigerating capacity or cooling capacity can be achieved, and an excellent COP can be realized. In particular, the refrigerating machine oil having a viscosity reduction rate of 70 to 80% before and after the dissolution of the refrigerant was preferable because compatibility and lubricity of the refrigerating machine oil and the refrigerant were easily compatible with each other.

1... Compressor, 2... Condenser, 3... Expansion mechanism, 4... Evaporator, 5... Flow path, 6... Refrigerant circulation system, 10... Refrigerator.

Claims (3)

A refrigerator having a compressor, a condenser, an expansion mechanism, and a refrigerant circulation system having an evaporator, wherein the refrigerant circulation system is filled with a refrigerant and refrigerating machine oil,
The refrigerating machine oil has a kinematic viscosity at 100° C. of 3 mm ² /s or more and 9 mm ² /s or less,
Working fluid consisting of the refrigerating machine oil and the refrigerant, the temperature 80 ° C., shows the refrigerant solution viscosity of 2.4~3.6mm ² / s at the conditions of absolute pressure 3.4 MPa,
The refrigerator in which the viscosity reduction rate of the refrigerator oil before and after the refrigerant is dissolved is 85% or less, which is calculated according to the following formula (1) .
Viscosity decrease rate (%)=(kinematic viscosity-refrigerant dissolution viscosity)/kinematic viscosity×100 (1)
[In the formula (1), the kinematic viscosity means the kinematic viscosity (mm ² /s) of the refrigerating machine oil at 80° C. , and the refrigerant dissolution viscosity is the refrigerant dissolution viscosity at a working fluid temperature of 80° C. and an absolute pressure of 3.4 MPa. It means (mm ² /s). ] A compressor, a condenser, an expansion mechanism, a method of manufacturing a refrigerator including a refrigerant circulation system having an evaporator,
A step of filling the refrigerant circulation system with a refrigerant and refrigerating machine oil;
The refrigerating machine oil has a kinematic viscosity at 100° C. of 3 mm ² /s or more and 9 mm ² /s or less,
Working fluid consisting of the refrigerating machine oil and the refrigerant, the temperature 80 ° C., shows the refrigerant solution viscosity of 2.4~3.6mm ² / s at the conditions of absolute pressure 3.4 MPa,
A method of manufacturing a refrigerator, wherein a viscosity reduction rate of the refrigerator oil before and after dissolution of a refrigerant is 85% or less calculated according to the following formula (1) .
Viscosity decrease rate (%)=(kinematic viscosity-refrigerant dissolution viscosity)/kinematic viscosity×100 (1)
[In the formula (1), the kinematic viscosity means the kinematic viscosity (mm ² /s) of the refrigerating machine oil at 80° C. , and the refrigerant dissolution viscosity is the refrigerant dissolution viscosity at a working fluid temperature of 80° C. and an absolute pressure of 3.4 MPa. It means (mm ² /s). ] A method for improving the COP of a refrigerator, which comprises a refrigerant circulation system having a compressor, a condenser, an expansion mechanism, and an evaporator, and in which the refrigerant circulation system is filled with a refrigerant and refrigerating machine oil. ,
As a working fluid composed of the refrigerant and the refrigerating machine oil, a working fluid having a refrigerant dissolution viscosity of 2.4 to 3.6 mm ² /s at a temperature of 80° C. and an absolute pressure of 3.4 MPa is used .
As the refrigerating machine oil, a refrigerating machine oil having a kinematic viscosity at 100° C. of 3 mm ² /s or more and 9 mm ² /s or less and a viscosity decrease rate before and after melting of a refrigerant calculated according to the following formula (1) is 85% or less. how to improve the COP by using.
Viscosity decrease rate (%)=(kinematic viscosity-refrigerant dissolution viscosity)/kinematic viscosity×100 (1)
[In the formula (1), the kinematic viscosity means the kinematic viscosity (mm ² /s) of the refrigerating machine oil at 80° C. , and the refrigerant dissolution viscosity is the refrigerant dissolution viscosity at a working fluid temperature of 80° C. and an absolute pressure of 3.4 MPa. It means (mm ² /s). ]

Images