JP6924888B1 - Refrigeration cycle equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle apparatus using a mixed refrigerant containing trifluoroiodomethane, which suppresses deterioration of the refrigerant and prevents malfunction of equipment for a long period of time. A refrigeration cycle device 100 including a compressor 3 for compressing a refrigerant, a four-way valve 4 for switching a circulation direction of the refrigerant, a condenser, a decompressor, and an evaporator, wherein the refrigerant is trifluoro. It is a mixed refrigerant containing iodomethane and has a steam pressure of 1.1 MPa or more and 1.8 MPa or less at 25 ° C., and the compressor 3 has a compression mechanism unit and a motor for driving the compression mechanism unit in a closed container. It is a sealed electric compressor filled with refrigerating machine oil that lubricates the sliding parts. The refrigerating machine oil is a polyol ester oil having a total acid value of 0.1 mgKOH / g or less, and the refrigerating cycle is operated. The refrigerant pipe 120 in the section where the refrigerant reaches a high temperature of 70 ° C. or higher is a steel pipe, a stainless steel pipe, an aluminum pipe, or an aluminum alloy pipe. [Selection diagram] Fig. 1

Description

The present invention relates to a refrigeration cycle device using a refrigerant having a small Global Warming Potential (GWP).

Traditionally, various measures against climate change have been taken internationally to prevent global warming. At the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21) held in 2015, the Paris Agreement was adopted and long-term goals to be achieved in the future were set. The Paris Agreement aims to keep the global average temperature rise well below 2 ° C compared to before the Industrial Revolution and to pursue efforts to keep it at 1.5 ° C.

In Japan, legislation is underway to prevent global warming related to fluorine compounds. Regarding the use and management of fluorine-based refrigerants used in refrigeration and air-conditioning equipment, regulated equipment and regulated substances are stipulated in the "Act on the Rational Use of CFCs and the Appropriate Management (CFC Emission Control Act)".

The regulated substances are ozone-depleting substances (mainly fluorine compounds with chlorine or bromine bound) specified in the "Act on the Protection of the Ozone Layer by Regulation of Specified Substances, etc." and "Promotion of Global Warming Countermeasures". It is a greenhouse gas substance (mainly a high GWP substance consisting of hydrogen, fluorine and carbon) listed in the "Law".

Currently, GWP, which is an index showing the degree of environmental impact, is set as a target value by a weighted average for each designated product due to the revision of the Freon Emission Control Law. For home air conditioners, 750 by 2018, for store / office air conditioners, 750 by 2020, for condensin units and stationary refrigeration units (hereinafter abbreviated as refrigerators, etc.) The goal is to reach 1500 by 2025.

Most household air conditioners are being switched to slightly flammable HFCs (Hydrofluorocarbons) 32 due to amendments to other laws and regulations. On the other hand, in multi-air conditioners (multi-room air conditioners) and refrigerators for buildings, the amount of refrigerant filled is large and the risk of refrigerant leakage is high, so it is difficult to apply a slightly flammable refrigerant.

Traditionally, as an international measure to prevent global warming, regulations under the Montreal Protocol have been tightened. Initially, the substances subject to regulation were the specified substances stipulated in Japan's "Act on the Protection of the Ozone Layer by Regulation of Specified Substances, etc." However, at the 28th Montreal Protocol Conference of the Parties (MOP28) held in Kigali, Rwanda in October 2016, regulations were also imposed on CFC substitutes, etc. listed in Japan's "Act on Promotion of Global Warming". It was to be expanded.

In the Kigari revision, the production and consumption of regulated substances will be -10% in 2019, -40% in 2024, -70% in 2029, and -80% in 2034, based on 2011-2013. , It was agreed to be -85% in 2036. In response to this agreement, it is expected that the target value can be achieved by the current Freon emission control law until 2024. However, it is expected that it will be difficult to achieve the regulatory targets after 2029.

Conventionally, R410A [HFC32 / HFC125 (50/50% by weight)] and R404A [HFC125 / HFC143a / HFC134a (44/52/4% by weight)] have been used as the refrigerant of the refrigerating air conditioner. However, since R410A has a high GWP = 1924 and R404A has a high GWP = 3943, in recent years, replacement with an alternative refrigerant having a lower GWP has been promoted. The GWP of the refrigerant and the combustibility are in a contradictory relationship, and when the GWP of the refrigerant is lowered, the combustibility tends to increase.

As alternative refrigerants, difluoromethane (HFC32) (GWP = 677), 2,3,3,3-tetrafluoropropene (HFO (Hydrofluoroolefin) 1234yf) are available because of their thermophysical properties, low GWP, low toxicity, and low flammability. ) (GWP = 0), 1,3,3,3-tetrafluoropropene (HFO1234ze) (GWP = 1), trifluoroethane (HFO1123) (GWP <1), 3,3,3-trifluoropropene (HFO1243zf) ) (GWP = 0) is known.

Further, a mixed refrigerant of HFO and HFC32, HFC125, HFC134a and the like, hydrocarbons such as propane and propylene, and hydrofluorocarbons having a low GWP such as monofluoroethane (HFC161) and difluoroethane (HFC152a) are known. Further, a low boiling point compound which is halogenated with iodine, bromine, chlorine or the like to make it nonflammable is also known.

Slightly flammable HFC32 is used as a refrigerant for home room air conditioners and commercial package air conditioners. In the revision of the Refrigeration Safety Regulations of the High Pressure Gas Safety Act (November 2016), HFC32, HFO1234yf, and HFO1234ze were classified as "inert gas". However, since these refrigerants are slightly flammable, they are also labeled as "specific inert gas". For equipment with 5 tons or more of refrigeration, it is necessary to have a ventilation device / equipment structure to prevent the leaked refrigerant from staying, and it is necessary to install a detection and alarm equipment in a place where the leaked refrigerant tends to stay. Against this background, the application of low GWP microflammable refrigerants has not progressed in air conditioners such as multi-room air conditioners for buildings, and R410A is currently used.

On the other hand, as a refrigerant for a refrigerator, a nonflammable mixed refrigerant having a GWP of 1500 or less and containing HFO1234yf and HFO1234ze has attracted attention in relation to the Freon emission suppression method. For example, refrigerators using R448A (HFC32 / HFC125 / HFC134a / HFO1234ze / HFO1234yf) and R449A (HFC32 / HFC125 / HFC134a / HFO1234yf) have been commercialized. However, since R448A and R449A cannot be made incombustible unless the GWP is kept at about 1100 to 1400, it is necessary to suppress combustibility in order to further reduce the GWP.

Under such circumstances, R466a, which is a low GWP and nonflammable mixed refrigerant containing _{trifluoroiodomethane (CF 3 I), has attracted attention.} According to R466a, since it is possible to obtain a refrigerating capacity close to that of R410A used in current multi air conditioners for buildings, it is possible to provide an air conditioner with high environmental compatibility without complicated installation and no need for major design changes. Is expected.

Refrigerant cycle devices that utilize thermodynamic refrigeration cycles, such as air conditioners, are equipped with a refrigerant circuit for circulating refrigerant. Generally, as a refrigerant pipe constituting a refrigerant circuit, a copper pipe is used from the viewpoints of mechanical strength, high workability, low material cost, and the like. Patent Document 1 describes an air conditioner in which a refrigerant pipe is made of a ductile stainless steel material instead of a copper pipe.

Special Publication No. 2020-510808

According to the mixed refrigerant containing trifluoroiodomethane (CF ₃ I), it is possible to suppress the combustibility while keeping the GWP low. Therefore, a refrigeration cycle device using a refrigerant having both low GWP and low combustibility can be used. Obtainable. However, CF 3 _I, the water, oxygen, refrigerating machine oil, a resin material, the metal material or the like is present, resulting them and direct or indirect chemical reaction, with CF 3 _I itself is decomposed, hydrogen fluoride, Produces degradation products such as hydrogen iodide.

In particular, since a copper pipe is used as a refrigerant pipe in a refrigeration cycle device such as an air conditioner, copper iodide (CuI) is generated on the inner surface of the copper pipe through which a mixed refrigerant containing _{CF 3 I flows.} Has been confirmed. Copper iodide forms sparingly soluble granules and sludge, exfoliates from the inner surface of the copper tube, and circulates in the refrigerant circuit together with the refrigerant.

Copper iodide generated in the refrigerant circuit may cause clogging of the four-way valve, expansion valve, etc., or may cause biting into the sliding part of the valve, which may cause malfunction. There is. Further, the sealed compressor is provided with a screw pump for refueling in the shaft, and copper iodide is deposited in the flow path of the refueling pump, so that there is a concern about malfunction due to a decrease in the amount of refueling.

Further, in a portion where the copper tube is a refrigerant pipe becomes hot, not only generation of copper iodide, decomposition itself of the CF 3 _I is also likely to be promoted by the heat have been suggested. Therefore _{, with respect to a refrigeration cycle device using a mixed refrigerant containing CF 3} I, a technique for suppressing the production of copper iodide and the deterioration of the refrigerant itself and reducing the malfunction of equipment such as valves and pumps is desired.

In Patent Document 1, the refrigerant pipe is made of a ductile stainless steel material instead of a copper pipe. However, since R32 is used as the refrigerant, it is considered unnecessary to take measures against copper iodide on the air conditioner. Since this ductile stainless steel material has a large amount of Cu of 1.0 to 4.0 wt%, even if _{a mixed refrigerant containing CF 3} I is used, there is a high possibility that a large amount of copper iodide will be produced, and as a countermeasure. Insufficient.

Further, in a refrigerating cycle device such as an air conditioner, if the entire refrigerant pipe is changed to a pipe other than the copper pipe, it becomes difficult to process and connect the refrigerant pipe at the installation site or the like, which causes problems in strength and material cost.

Therefore, in the present invention, despite the use of a mixed refrigerant containing trifluoroiodomethane, deterioration of the refrigerant is suppressed, the amount of copper iodide produced by the reaction of the refrigerant is reduced, and malfunction of the device is long-term. It is an object of the present invention to provide a refrigerating cycle apparatus which is prevented from being prevented.

In order to solve the above problems, the refrigerating cycle apparatus according to the present invention condenses a compressor that compresses the refrigerant, a four-way valve that switches the circulation direction of the refrigerant compressed by the compressor, and the refrigerant flowing from the four-way valve. A refrigeration cycle device including a condenser, a decompressor for decompressing the refrigerant condensed by the condenser, and an evaporator for evaporating the refrigerant decompressed by the decompressor, wherein the refrigerant is trifluoroiode. It is a mixed refrigerant containing methane, and the steam pressure at 25 ° C. is 1.1 MPa or more and 1.8 MPa or less. It is a sealed electric compressor filled with refrigerating machine oil that lubricates the sliding parts, and the refrigerating machine oil is a polyol ester oil having a total acid value of 0.1 mgKOH / g or less, and is used in the refrigeration cycle. refrigerant pipe which connects between the compressor refrigerant is a section made of a high temperature above 70 ° C. during operation with the four-way valve, stainless steel weight C u is less than 0.5 mass%, Cu amount is aluminum tubes or Cu amount is less than 0.5% by mass Ri aluminum alloy tube der less than 0.5 wt%, the refrigerant pipe connecting between the evaporator and the condenser is copper tube.

According to the present invention, despite the use of a mixed refrigerant containing trifluoroiodomethane, deterioration of the refrigerant is suppressed, the amount of copper iodide produced by the reaction of the refrigerant is reduced, and malfunction of the device is long-term. A refrigeration cycle device that is prevented can be provided.

It is a refrigerating cycle block diagram which shows an example of the multi air conditioner for a building which is a refrigerating cycle apparatus. It is a vertical cross-sectional view which shows an example of a closed type electric compressor. It is a scanning electron microscope image which observed the surface of the metal tube after the accelerated deterioration test of 150 degreeC. It is a scanning electron microscope image which observed the surface after the durability test of the refrigerant pipe connected to the discharge side of a compressor.

Hereinafter, the refrigeration cycle apparatus according to the embodiment of the present invention will be described in detail with reference to the drawings.

<Refrigeration cycle equipment>
The refrigeration cycle device according to the present embodiment is a device having an ability to cool a cooling target by utilizing a thermodynamic refrigeration cycle using a refrigerant. The refrigeration cycle device may be capable of performing a thermal cycle opposite to the refrigeration cycle, as long as it is capable of performing cooling. This refrigeration cycle device can be applied to various refrigeration and air conditioning devices such as an air conditioner.

The refrigeration cycle apparatus according to the present embodiment includes a compressor that compresses the refrigerant, a four-way valve that switches the circulation direction of the refrigerant compressed by the compressor, a condenser that condenses the refrigerant flowing from the four-way valve, and a condenser. A decompressor for decompressing the decompressed refrigerant and an evaporator for evaporating the decompressed refrigerant by the decompressor are provided. As the compressor, a closed electric compressor having a compression mechanism and a motor for driving the compression mechanism and filled with refrigerating machine oil for lubricating the sliding portion is used in a closed container. ..

The refrigeration cycle apparatus according to the present embodiment includes an accumulator that separates droplets from a refrigerant containing droplets evaporated by an evaporator and temporarily stores them, a dryer that removes water in the refrigerant, and a dryer, if necessary. A receiver tank for adjusting excess refrigerant and an oil separator for separating refrigerating machine oil from the refrigerant discharged by the compressor can be provided.

In the refrigeration cycle apparatus according to the present embodiment _{, a mixed refrigerant containing trifluoroiodomethane (CF 3} I) is used as the refrigerant. When _{a mixed refrigerant containing CF 3} I is used, if the refrigerant pipe through which the refrigerant flows is a copper pipe, copper iodide (CuI) is generated on the inner surface of the copper pipe. CuI is caused by the decomposition of CF 3 _I, the amount generated in a section comprising a high temperature in the refrigerant circuit is often, it has been confirmed in actual.

Therefore, in the refrigeration cycle apparatus according to the present embodiment, a metal pipe having a low copper content is used as the refrigerant pipe in the section where the refrigerant becomes high temperature of 70 ° C. or higher during the operation of the refrigeration cycle. Examples of the section where the refrigerant reaches a high temperature of 70 ° C. or higher include a refrigerant pipe on the discharge side of the compressor. Specific examples of metal pipes having a low copper content include steel pipes, stainless steel pipes, aluminum pipes, aluminum alloy pipes, and the like, as will be described later.

Here, the refrigeration cycle apparatus according to the present embodiment and the compressor used in the refrigeration cycle apparatus will be described with reference to specific examples.

FIG. 1 is a refrigeration cycle configuration diagram showing an example of a multi air conditioner for a building, which is a refrigeration cycle device.
The refrigeration cycle device according to the present embodiment can be applied as an air conditioner such as a multi-room air conditioner for buildings as shown in FIG.

As shown in FIG. 1, the building multi air conditioner 100 includes an outdoor unit 1 and indoor units 2a and 2b. In FIG. 1, the building multi air conditioner 100 includes two indoor units 2a and 2b, but the building multi air conditioner 100 has three or more indoor units (2a, 2b, ...・ ・) Can be provided.

In FIG. 1, the outdoor unit 1 includes a compressor 3, a four-way valve 4, an outdoor heat exchanger (condenser / evaporator) 5, an outdoor expansion valve (decompressor) 6, a receiver tank 7, and a dryer 8. The accumulator 9 and the outdoor blower 10 are provided.

The indoor units 2a and 2b include indoor heat exchangers (evaporators / condensers) 11a and 11b, indoor expansion valves (decompressors) 12a and 12b, and indoor blowers 13a and 13b, respectively. When the multi air conditioner 100 for a building is provided with two or more indoor units (2a, 2b, ...), Each indoor unit is provided in the same configuration and is provided with a refrigerant pipe so as to form a parallel refrigeration cycle. You can connect.

The compressor 3, the four-way valve 4, the outdoor heat exchanger 5, the outdoor expansion valve 6, the receiver tank 7, the dryer 8 and the indoor heat exchangers 11a and 11b are connected in this order via a refrigerant pipe. The refrigerant pipe is connected to the four-way valve 4 from the indoor heat exchangers 11a and 11b, and is connected to the compressor 3 again from the four-way valve 4 via the accumulator 9.

The compressor 3 is a closed electric compressor, and has a compression mechanism unit for compressing the refrigerant and a motor for driving the compression mechanism unit built in the closed container. The compressor 3 includes a closed container constituting the main body, and has a suction port for sucking the refrigerant into the compression mechanism unit and a discharge port for discharging the refrigerant compressed by the compression mechanism unit.

A suction pipe 110 is connected to the suction side of the compressor 3. The other end of the suction pipe 110 is connected to the outflow side of the accumulator 9. Further, a discharge pipe 120 is connected to the discharge side of the compressor 3. The other end of the discharge pipe 120 is connected to the four-way valve 4.

The four-way valve 4 has a built-in valve body such as a slide valve for switching the flow path inside the valve body provided with the flow path, and has an inlet port for flowing the refrigerant into the flow path and a refrigerant in the flow path. It has an outlet port for flowing out from and two switching ports. The two switching ports are switched between the state of communication with the inlet side and the outlet side and the direction of fluid inflow and outflow depending on the operation of the valve body.

The accumulator 9 is a device that separates gas and liquid from the gas refrigerant and the liquid refrigerant, and separates the droplets from the refrigerant containing the droplets and temporarily stores the droplets. The accumulator 9 includes a container for storing the separated liquid refrigerant, and has an inflow pipe for allowing the refrigerant to flow into the container and an outflow pipe for allowing the refrigerant from which the droplets have been separated to flow out of the container. One end of the inflow pipe opens to the upper part in the container. The outflow pipe is provided as a U-shaped pipe, one end of which is open to the upper part of the container, and the droplets in the gas refrigerant are separated by centrifugal force or collision.

A refrigerant pipe 130 is connected to the inflow side of the accumulator 9. The other end of the refrigerant pipe 130 is connected to the outlet port of the four-way valve 4. A refrigerant pipe 140 connected to the outdoor heat exchanger 5 and a refrigerant pipe 150 including a liquid pipe connected to the indoor heat exchangers 11a and 11b are connected to the switching port of the four-way valve 4, respectively. The outdoor heat exchanger 5 and the indoor heat exchangers 11a and 11b are connected by a refrigerant pipe 160 including a gas pipe.

The suction pipe 110 and the discharge pipe 120 include a refrigerant pipe 130 that connects the four-way valve 4 and the accumulator 9, a refrigerant pipe 140 that connects the four-way valve 4 and the outdoor heat exchanger 5, and a four-way valve 4 and the indoor heat exchanger. Similar to the refrigerant pipe 150 connecting the 11a and 11b, and the refrigerant pipe 160 connecting the outdoor heat exchanger 5 and the indoor heat exchangers 11a and 11b via the outdoor expansion valve 6 and the indoor expansion valves 12a and 12b. , Corresponds to the refrigerant pipe through which the refrigerant flows.

These devices and the refrigerant pipes connecting the devices form a refrigerant circuit as a circulation path for circulating the refrigerant between the outdoor unit 1 and the indoor units 2a and 2b. _{A mixed refrigerant containing CF 3} I is sealed in the refrigerant circuit. Further, the compressor 3 is filled with a predetermined polyol ester oil as the refrigerating machine oil for the purpose of lubrication, sealing of the refrigerant, cooling and the like.

The compressor 3 sucks in the gas refrigerant, compresses the low-temperature low-pressure gas refrigerant adiabatically, and discharges the high-temperature and high-pressure gas refrigerant. The four-way valve 4 can switch the circulation direction of the refrigerant discharged from the compressor 3 in the refrigerant circuit according to the thermodynamic cycle. The outdoor heat exchanger 5 exchanges heat between the refrigerant and the outside air, and acts as a condenser during the cooling operation and as an evaporator during the heating operation. The outdoor blower 10 is provided to blow outside air to the outdoor heat exchanger 5, and promotes heat exchange between the refrigerant and the outside air.

The outdoor expansion valve 6 is composed of, for example, an electronic expansion valve, a temperature expansion valve, or the like, and functions as a decompressor during a heating operation. The receiver tank 7 is a container for adjusting the surplus refrigerant. The gas refrigerant separated from the liquid refrigerant is temporarily stored in the receiver tank 7. Although the receiver tank 7 is provided in FIG. 1, the receiver tank 7 may not be provided. The receiver tank 7 may not be installed depending on the model of the refrigeration cycle device.

The dryer 8 is provided to remove water in the refrigerant. The dryer 8 includes an in-line type container, and the container is filled with a desiccant. As the desiccant, for example, synthetic zeolite such as molecular sieve having a pore size for adsorbing water can be used. Although the dryer 8 is provided in the bypass branched from the mainstream pipe constituting the refrigerant circuit in FIG. 1, it can also be provided in the mainstream pipe.

The indoor heat exchangers 11a and 11b exchange heat between the refrigerant and the indoor air, and act as an evaporator during the cooling operation and as a condenser during the heating operation. The indoor expansion valves 12a and 12b are composed of, for example, an electronic expansion valve, a thermal expansion valve, and the like, and act as a decompressor during the cooling operation. The indoor blowers 13a and 13b are provided to blow indoor air to the indoor heat exchangers 11a and 11b, and promote heat exchange between the refrigerant and the indoor air.

Cooling by the building multi air conditioner 100 is performed by the following principle. The high-temperature and high-pressure refrigerant gas adiabatically compressed by the compressor 3 is sent to the outdoor heat exchanger 5 through the four-way valve 4. Then, the refrigerant gas is cooled by heat exchange with the outside air in the outdoor heat exchanger 5 that acts as a condenser to become a high-pressure liquid refrigerant. The high-pressure liquid refrigerant is depressurized by the indoor expansion valves 12a and 12b and expands to become a gas-liquid two-phase refrigerant (a low-temperature low-pressure liquid refrigerant containing a small amount of refrigerant gas).

The gas-liquid two-phase refrigerant is sent to the individual indoor heat exchangers 11a and 11b. Then, the indoor heat exchangers 11a and 11b that act as evaporators evaporate by heat exchange with the indoor air to take heat and become a low-temperature low-pressure gas refrigerant. The low-temperature low-pressure gas refrigerant passes through the four-way valve 4 and enters the accumulator 9, and the low-temperature low-pressure liquid refrigerant that has not completely evaporated is separated. The low-temperature low-pressure gas refrigerant from which the liquid refrigerant has been separated returns to the compressor 3. After that, the same cycle is repeated and cooling is continued.

Heating by the building multi air conditioner 100 is performed in a cycle opposite to that during cooling. The high-temperature and high-pressure refrigerant gas adiabatically compressed by the compressor 3 is sent to the individual indoor heat exchangers 11a and 11b by switching the four-way valve 4. Then, the indoor heat exchangers 11a and 11b acting as condensers give heat to the indoor air, and then the outdoor heat exchanger 5 acting as an evaporator removes heat from the outside air. Such a similar cycle is repeated to continue heating.

Although the four-way valve 4 is directly connected to the discharge side of the compressor 3 in FIG. 1, an oil separator is provided between the discharge side of the compressor 3 and the four-way valve 4. May be good. An oil separator is a device that separates refrigerating machine oil from a mixture of refrigerant and refrigerating machine oil. The oil separator includes a refrigerant pipe on the inlet side that sends the refrigerant from the compressor 3 to the oil separator, a refrigerant pipe on the outlet side that sends the refrigerant from the oil separator toward the four-way valve 4, and a refrigeration separated from the refrigerant. An oil return pipe that returns the machine oil to the compressor 3 or the accumulator 9 is connected.

Further, in FIG. 1, the building multi air conditioner 100 is configured such that a plurality of indoor units (2a, 2b, ...) Cool or heat at the same time, but the cooling or heating is switched for each indoor unit. May be. The switching operation for each indoor unit can be performed, for example, by using three pipes for the refrigerant circuit for each indoor unit and providing a switching valve for switching the flow of the refrigerant for each indoor unit and each refrigerant circuit.

Since the multi air conditioner 100 for buildings as shown in FIG. 1 has a large air conditioning capacity and a large amount of refrigerant filled, the use of a refrigerant having a lower flammability than HFC32 or the like is used from the viewpoint of reducing the risk of refrigerant leakage. Is desired. Further, for air conditioners such as multi air conditioners for buildings, a refrigerant having a GWP of 750 or less is recommended. Therefore, a mixed refrigerant containing _{CF 3} I, which achieves both low GWP and low combustibility, is preferably used.

In an air conditioner as shown in FIG. 1, there is a discharge side of the compressor 3 where the refrigerant becomes hot during the operation of the refrigeration cycle. Among the refrigerant pipes, a discharge pipe 120 connected to the discharge side of the compressor 3 can be mentioned as a section where the temperature becomes high during the operation of the refrigeration cycle. When an oil separator is provided between the discharge port of the compressor 3 and the four-way valve 4, the refrigerant pipe connecting the compressor 3 and the oil separator or the refrigerant pipe connecting the oil separator and the four-way valve 4 However, it corresponds to the section where the temperature becomes high during the operation of the refrigeration cycle.

FIG. 2 is a vertical cross-sectional view showing an example of a closed electric compressor.
The refrigeration cycle apparatus according to the present embodiment may include, for example, a scroll-type closed electric compressor as shown in FIG. 2 as a compressor for compressing the refrigerant. The sealed electric compressor can be used as the compressor 3 of the multi air conditioner 100 for buildings shown in FIG.

As shown in FIG. 2, the closed electric compressor 3 has a fixed scroll member 20 having a spiral fixed wrap 20a provided perpendicular to the end plate, and a spiral shape having substantially the same shape as the fixed wrap 20a. A swivel scroll member 21 having the swivel lap 21a, a frame 22, a crankshaft 23 for swiveling the swivel scroll member 21, a motor 24 for driving the crankshaft 23, and a closed container 25 incorporating these are provided. ing.

The fixed scroll member 20 is bolted to the frame 22. An old dam ring that regulates the rotation of the swivel scroll member 21 is slidably engaged with the back surface of the swivel scroll member 21. The swivel scroll member 21 is supported by a swivel bearing fitted with an eccentric pin that drives the swivel scroll member 21 eccentrically.

The fixed scroll member 20 and the swivel scroll member 21 are arranged so that the fixed lap 20a and the swivel lap 21a are opposed to each other so as to mesh with each other, and form a compression mechanism portion for compressing the refrigerant. A compression chamber 26 is formed between the fixed lap 20a and the swirling lap 21a.

The crankshaft 23 is supported in a state in which the main shaft portion is rotatable by the main bearing 30 which is a rolling bearing. Further, the sub-shaft portion is rotatably supported by the sub-bearing 31 which is a rolling bearing. A balance weight is attached to the middle portion of the crankshaft 23.

The rotation of the crankshaft 23 is driven by the motor 24 at a constant rotation speed or a rotation speed corresponding to a voltage controlled by an inverter. When the crankshaft 23 is rotated by the operation of the motor 24, the swivel scroll member 21 is eccentrically swiveled with respect to the fixed scroll member 20.

In the closed electric compressor 3, a suction pipe for sucking the refrigerant from the refrigerant pipe is provided in the upper part of the closed container 25. The suction pipe communicates with a suction port to the compression chamber 26 provided on the outside of the fixed scroll member 20. When the swivel scroll member 21 swivels, the outermost compression chamber 26 moves toward the center of the compression mechanism while gradually reducing its volume. Along with this operation, the refrigerant introduced into the compression chamber 26 through the suction port is continuously compressed.

When the compression chamber 26 moves to the center of the compression mechanism portion, it communicates with the discharge port 27 provided so as to penetrate the fixed scroll member 20. Inside the closed container 25, there are an upper space and a lower space with the fixed scroll member 20 sandwiched therein. The refrigerant gas compressed in the compression chamber 26 is discharged from the discharge port 27 into the upper space in the closed container 25. The refrigerant gas released into the upper space moves to the lower space through a plurality of discharge gas passages penetrating the fixed scroll member 20. Then, it is discharged to the refrigerant pipe from the discharge pipe 28 penetrating the closed container 25 provided in the lower space.

In the closed container 25, an oil reservoir 32 for accumulating refrigerating machine oil is provided below the motor 24. The refrigerating machine oil in the oil reservoir 32 is sucked during the operation of the compression mechanism. Then, through the oil hole 29 provided in the crankshaft 23, the sliding portion between the swivel scroll member 21 and the crankshaft 23, the rolling bearing of the main bearing 30 that supports the main shaft portion of the crankshaft 23, and the crankshaft. It is supplied to the rolling bearing or the like of the auxiliary bearing 31 that supports the auxiliary shaft portion of 23.

According to such a closed type electric compressor 3, since it is a scroll type, the refrigerant leakage and the area of the sliding portion are reduced, and high energy efficiency and operation reliability can be obtained. In FIG. 2, the sealed electric compressor 3 is a scroll compressor, but the compressor constituting the refrigeration cycle device includes, for example, a screw compressor and a rotary compressor in addition to the scroll compressor. , Twin rotary compressor, two-stage compressor rotary compressor, swing type compressor in which rollers and vanes are integrated, or the like may be used.

Next, the details of the refrigerant and the refrigerating machine oil used in the refrigerating cycle apparatus according to the present embodiment will be described.

<Refrigerant>
_{A mixed refrigerant containing trifluoroiodomethane (CF 3} I) is used as the refrigerant of the refrigeration cycle apparatus, but preferred refrigerants are difluoromethane (HFC32), pentafluoroethane (HFC125) and trifluoroiodomethane (CF ₃ I). ) Is a mixed refrigerant. The mixed refrigerant may contain only these three components as a refrigerant component, or may contain other refrigerant components in addition to these three components. Additives may or may not be added to the mixed refrigerant.

Of the refrigerant components, HFC32 is mainly used to ensure high refrigerating capacity and energy efficiency. Further, HFC125 is mainly used for reducing the temperature gradient. In addition, CF ₃ I is mainly used to reduce the GWP and combustibility of the mixed refrigerant itself. In the present specification, the temperature gradient means the temperature difference between the start temperature and the end temperature of the phase change (evaporation / condensation) of the refrigerant.

According to these three components, it is possible to obtain a mixed refrigerant having excellent refrigerating capacity and energy efficiency, a small temperature gradient, and low GWP and combustibility. Therefore, by using such a mixed refrigerant, it is possible to obtain a refrigeration cycle device having high safety and environmental compatibility, and excellent refrigerating capacity and power efficiency.

The refrigerant of the refrigeration cycle apparatus has a global warming potential (GWP) of 750 or less, preferably 500 or less, and more preferably 150 or less. When the GWP is 750 or less, the refrigerant has excellent environmental performance, is highly compliant with legal regulations, and can be used not only in refrigerators but also in air conditioners. The GWP of the refrigerant can be adjusted by changing the composition ratio of the mixed refrigerant. HFC32 is GWP = 677, HFC125 is, GWP = 3500, CF ₃ I is a GWP = 0.4.

The refrigerant of the refrigeration cycle apparatus preferably has a saturated vapor pressure of 1.1 MPa or more and 1.8 MPa or less at 25 ° C. When the saturated vapor pressure is in this range, it is equivalent to the conventional general refrigeration cycle device using R32, R410A, R404A, etc., without making major changes in the system, design, construction method of refrigerant piping, etc. Refrigerating capacity, refrigerant encapsulation, etc. can be obtained. The saturated vapor pressure of the refrigerant can be adjusted by changing the composition ratio of the mixed refrigerant. Saturated vapor pressure at 25 ° C. is, HFC32: about 1.69MPa, HFC125: about 1.38MPa, _CF 3 I: approximately 0.5 MPa.

As the refrigerant of the refrigeration cycle apparatus, HFC32 is preferably 10% by weight or more, more preferably 20% by weight or more and 80% by weight or less, further preferably 20% by weight or more and 60% by weight or less, and particularly preferably 30% by weight or more and 50% by weight or less. % Or less. Further, HFC125 is preferably 5% by weight or more and 25% by weight or less. Further, CF ₃ I is preferably 30% by weight or more and 60% by weight or less. With such a composition, a mixed refrigerant containing HFC32 is slightly combustible, and pseudo co fluorinated at HFC125, turned into a low GWP in CF ₃ I, and sufficiently non-flammable by a small amount of HFC125 and CF ₃ I Can be transformed.

In addition to the above three components, the refrigerant of the refrigeration cycle apparatus may contain CO ₂ , hydrocarbons, ether, fluoroether, fluoroalkene, HFC, HFO, HClFO, HBrFO and the like as other refrigerant components.

In addition, "HFC" indicates hydrofluorocarbon. "HFO" is a hydrofluoroolefin composed of a carbon atom, a fluorine atom and a hydrogen atom, and has at least one carbon-carbon double bond. "HClFO" consists of a carbon atom, a chlorine atom, a fluorine atom and a hydrogen atom, and has at least one carbon-carbon double bond. "HBrFO" consists of a carbon atom, a bromine atom, a fluorine atom and a hydrogen atom, and has at least one carbon-carbon double bond.

Examples of HFC include difluoromethane (HFC32), pentafluoroethane (HFC125), 1,1,2,2-tetrafluoroethane (HFC134), 1,1,1,2-tetrafluoroethane (HFC134a), and trifluoroethane. (HFC143a), difluoroethane (HFC152a), 1,1,1,2,3,3,3-heptafluoropropane (HFC227ea), 1,1,1,3,3,3-hexafluoropropane (HFC236fa), 1 , 1,1,3,3-pentafluoropropane (HFC245fa), 1,1,1,3,3-pentafluoroethane (HFC365mfc) are exemplified.

Examples of fluoroalkenes include fluoroethane, fluoropropene, fluorobutene, chlorofluoroethane, chlorofluoropropene, and chlorofluorobutene.

Fluoroethane includes 1,1-difluoroethane (HFO1132a), (E) -1,2-difluoroethene (HFO1132 (E)), (Z) -1,2-difluoroethene (HFO1132 (Z)), and tri. Fluoroethane (HFO1123) is exemplified.

Examples of fluoropropene include 3,3,3-trifluoropropene (HFO1243zf), 1,3,3,3-tetrafluoropropene (HFO1234ze), 2,3,3,3-tetrafluoropropene (HFO1234yf), and HFO1225. Illustrated.

Examples of fluorobutene include C ₄ H ₄ F ₄ (HFO 1354), C ₄ H ₃ F ₅ (HFO 1345), and C ₄ H ₂ F ₆ (HFO 1336).

The chlorofluorohydrocarbons _{ethene, C 2 F 3 Cl (CTFE} ) are exemplified. Examples of chlorofluoropropene include 2-chloro-3,3,3-trifluoro-1-propene (HCFO1233xf) and 1-chloro-3,3,3-trifluoro-1-propene (HCFO1233zd).

<Refrigerator oil>
As the refrigerating machine oil of the refrigerating cycle apparatus, polyol ester oil (POE) can be used. Polyvinyl ether oil (PVE) and the like are also known as chemically synthesized oils for refrigeration and air conditioning. However, PVE easily undergoes a chemical reaction and deteriorates when heated to a high temperature in the presence of _{CF 3 I.} On the other hand, with POE, long-term lubrication and other effects can be obtained even in the presence of _{CF 3 I.} Further, since POE forms an oil film that is hard to break on the sliding surface, good lubricity can be obtained regardless of the presence or absence of an extreme pressure agent.

The polyol ester oil can be obtained by a condensation reaction of a polyhydric alcohol and a monovalent fatty acid. Examples of the polyhydric alcohol include neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and the like. Examples of monovalent fatty acids include n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, and 2-ethylhexanoic acid. Isooctanoic acid, 3,5,5-trimethylhexanoic acid and the like can be mentioned. As the polyhydric alcohol or monovalent fatty acid, one kind may be used, or a plurality of kinds may be used.

As the polyol ester oil, a pentaerythritol-based compound represented by the following chemical formula (1), a dipentaerythritol-based compound represented by the following chemical formula (2), or a mixture thereof is preferable. [However, in the chemical formulas (1) and (2), R ¹ represents an alkyl group having 4 to 9 carbon atoms, and may be the same as or different from each other. ]

R ¹ may be either a linear alkyl group or a branched alkyl group. Specific examples of R ¹ include n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, 3-pentyl group, tert-pentyl group, neopentyl group. Examples include a group, a 1-ethylpentyl group, an isohexyl group, a 2-ethylhexyl group and the like.

Pentaerythritol-based compound represented by Formula (1), and, dipentaerythritol based compound represented by the following chemical formula (2) as R ^1, it is preferred to have only a branched alkyl group. If it is substituted with a branched alkyl group, the ester group is less likely to react with water or the like mixed in the refrigerant circuit, so that deterioration of the refrigerating machine oil can be suppressed.

In addition to polyol ester oil, polyalkylene glycol oil, paraffin-based mineral oil, naphthen-based mineral oil, poly-α-olefin oil, soft alkylbenzene oil, and the like are also known as general refrigerating machine oils. However, these oils are not suitable as refrigerating machine oils because they are thermochemically unstable and easily react when used in combination with a mixed refrigerant containing _{CF 3 I.}

The refrigerating machine oil of the refrigerating cycle apparatus preferably has a kinematic viscosity at 40 ° C. of 22 mm ² / s or more and 84 mm ² / s or less. Within this range, sufficient compatibility with the refrigerant can be obtained even at a low temperature, so that it can be used without any problem in various types of closed electric compressors. Regardless of the type of compressor, the lubricity of the sliding portion of the compressor and the airtightness of the compression chamber when it is compatible with the refrigerant can be appropriately ensured.

The kinematic viscosity of the refrigerating machine oil can be adjusted mainly by changing the composition of the polyol ester oil. The kinematic viscosity of refrigerating machine oil can be measured based on standards such as ISO (International Organization for Standardization) 3104, ASTM (American Society for Testing and Materials) D445, D7042 and the like.

It is preferable that the refrigerating machine oil of the refrigerating cycle apparatus has a water content of 300 ppm by weight or less in a state of being sealed together with the refrigerant in the refrigerant circuit. The water content of the refrigerating machine oil is more preferably 200 ppm by weight or less, further preferably 150 ppm by weight or less, and particularly preferably 100 ppm by weight or less.

Generally, the water content of refrigerating machine oil is reduced during production. However, the water may be mixed in the refrigerating machine oil when the compressor is filled, or may enter the refrigerant circuit in which the refrigerating machine oil circulates. Moisture in the refrigerant circuit is mainly localized in the refrigerating machine oil phase, not in the refrigerant phase, during operation of the refrigerating cycle apparatus.

When the water content of the refrigerating machine oil is reduced to 300 ppm by weight or less, _{the reaction amount between the water content and CF 3} I or POE becomes extremely small, so that _{the hydrolysis of CF 3} I or POE can be greatly suppressed. When _{the decomposition of CF 3} I is suppressed, hydrogen iodide is no longer produced, and it is considered that the production of copper iodide due to the reaction with hydrogen iodide is also suppressed. Therefore, deterioration of the refrigerant itself, deterioration of refrigerating machine oil, and malfunction of equipment such as valves and pumps can be suppressed for a long period of time.

The water content of the refrigerating machine oil is, for example, the degree of decompression (vacuum degree, etc.) of vacuuming applied when drying the refrigerating machine oil, adjusting the atmosphere when filling the refrigerating machine oil, installing the refrigerant pipe, and the dryer to the refrigerant circuit.・ It can be reduced by installing a desiccant. The means for reducing the amount of water may be used in combination as appropriate.

The water content of the refrigerating machine oil can be measured by collecting the refrigerating machine oil compatible with the refrigerant from the refrigerant circuit and using it as a measurement sample, and using the Carl Fisher type coulometric titration method. The amount of water in the refrigerating machine oil (water content in oil) shall be measured according to JIS K 2275-3: 2015 "Crude oil and petroleum products-How to obtain water-Part 3: Karl Fisher type coulometric titration method". Can be done.

The total acid value of the refrigerating machine oil is preferably maintained at 0.1 mgKOH / g or less from the time of initial filling in the refrigerant circuit to the end of the test for measuring the total acid value. The total acid value of the refrigerating machine oil is more preferably 0.05 mgKOH / g or less, still more preferably 0.03 mgKOH / g or less.

The total acid value is used as an index of deterioration of refrigerating machine oil, and the larger the value, the more the deterioration of refrigerating machine oil is progressing. When _{a mixed refrigerant containing CF 3} I is used in combination with refrigerating machine oil, not only hydrolysis and oxidation of refrigerating machine oil but also _{formation of acidic components by the reaction of CF 3} I increases the total acid value of refrigerating machine oil. If the total acid value exceeds 0.1 mgKOH / g, there is a risk of corrosion of metal materials such as refrigerant piping and poor lubrication of the sliding parts of the compressor.

On the other hand, when the total acid value of the refrigerating machine oil is reduced to 0.1 mgKOH / g or less, corrosion of the metal material and poor lubrication of the sliding portion are greatly suppressed. On the other hand, _{when the reaction of CF 3} I is not suppressed, that is, when the material of the refrigerant pipe is not selected or the water content of the refrigerating machine oil is not reduced, when a non-POE is used as the refrigerating machine oil, or when an additive is added to the refrigerating machine oil. If not added, it is difficult to keep the total acid value below 0.1 mgKOH / g until the end of the test to measure the total acid value after the operation time corresponding to the accelerated deterioration test of 504 hours at 50 to 150 ° C. Is.

The total acid value of the refrigerating machine oil can be reduced mainly by adding an additive to the refrigerating machine oil or reducing the water content of the refrigerating machine oil. _{In addition, copper may react directly with CF 3} I itself on the metal surface, and the material of the refrigerant piping, especially in the section where the refrigerant becomes hot at about 70 ° C or higher during the operation of the refrigeration cycle. It can also be made smaller by selecting the material. The total acid value is defined as the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize the total acidic components contained in 1 g of oil. The total acid value can be measured according to JIS K 2501: 2003 "Petroleum products and lubricating oil-neutralization value test method".

The refrigerating machine oil of the refrigerating cycle apparatus may be added with a lubricity improver, an antioxidant, a stabilizer, an acid scavenger, a defoaming agent, a metal inactivating agent and the like as additives.

Examples of the lubricity improver include extreme pressure agents composed of thermochemically stable tertiary phosphates, for example, tricresyl phosphate, triphenyl phosphate, trixylenyl phosphate, cresyldiphenyl phosphate, 2-ethylhexyl diphenyl phosphate. , Tris (2-ethylhexyl) phosphate and the like can be used.

When added as an additive, the extreme pressure agent is preferably 0.1% by mass or more and 2.0% by mass or less with respect to 100% by mass of the refrigerating machine oil. However, POE has good lubricity without adding an extreme pressure agent. In addition, phosphoric acid esters such as tertiary phosphates are easily decomposed into deterioration products such as hydrogen fluoride generated by the reaction of _{CF 3 I.} Therefore, it is not necessary to add an extreme pressure agent to POE.

As the antioxidant, for example, a phenolic antioxidant such as DBPC (2,6-di-t-butyl-p-cresol) can be used. In general, the environment in refrigerating machine oil is such that the antioxidant is not easily consumed. However, when a mixed refrigerant containing _{CF 3} I is used, it is preferable to use an antioxidant because _{iodic acid (HIO 3) having an oxidizing power is generated.}

The antioxidant is preferably 0.1% by mass or more and 21.0% by mass or less with respect to 100% by mass of the refrigerating machine oil.

As the acid scavenger, for example, an aliphatic epoxy compound, an alicyclic epoxy compound, a monoterpene compound and the like can be used. Since the aliphatic epoxy compound reacts with water at a low temperature, the water contained in the refrigerating machine oil can be quickly captured in the early stage of operation. In addition, _{acidic substances generated by the CF 3} I reaction can be efficiently captured. The alicyclic epoxy compound remains in the refrigerant circuit for a long period of time and exhibits an action of continuously suppressing the total acid value.

Examples of the aliphatic epoxy compound include an alkyl glycidyl ester compound and an alkyl glycidyl ether compound. As the alkyl glycidyl ester compound, a monoglycidyl ester in which an alkyl group having 4 to 12 carbon atoms is bonded is preferable. As the alkyl glycidyl ether compound, monoglycidyl ether to which an alkyl group having 4 to 12 carbon atoms is bonded is preferable.

The alkyl group of the aliphatic epoxy compound may be linear or branched. Specific examples of the alkyl group include n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, 3-pentyl group, tert-pentyl group and neopentyl group. Examples include a group, a 1-ethylpentyl group, an isohexyl group, a 2-ethylhexyl group and the like.

Examples of the alicyclic epoxy compound include 1,2-epoxycyclohexane, 1,2-epoxycyclopentane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and bis (3,4-epoxycyclohexyl). Methyl) adipate, exo-2,3-epoxynorbornane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 2- (7-oxabicyclo [4.1.0] hept-3-yl)- Spiro (1,3-dioxane-5,3'-[7] oxabicyclo [4.1.0] heptane, 4- (1'-methylepoxyethyl) -1,2-epoxy-2-methylcyclohexane, 4 -Epoxyethyl-1,2-epoxycyclohexane and the like can be mentioned.

The acid scavenger is preferably 0.1% by mass or more and 2.0% by mass or less with respect to 100% by mass of the refrigerating machine oil. As the acid scavenger, it is preferable to use an aliphatic epoxy compound and an alicyclic epoxy compound in combination.

Next, the details of the refrigerant piping used in the refrigeration cycle device according to the present embodiment will be described.

In the refrigeration cycle apparatus according to the present embodiment, a metal pipe having a low copper content is used as the refrigerant pipe in the section where the refrigerant reaches a high temperature of 70 ° C. or higher during the operation of the refrigeration cycle. As the metal pipe having a low copper content, a metal pipe having a Cu content of less than 0.5% by mass, for example, a steel pipe, a stainless steel pipe, an aluminum pipe, an aluminum alloy pipe, or the like can be used.

In conventional refrigeration cycle devices such as air conditioners, copper pipes are used as refrigerant pipes from the viewpoints of mechanical strength, high workability, low material cost, and the like. A typical refrigerant pipe is a seamless pipe made of copper or a copper alloy. As the material of the refrigerant pipe, alloy numbers C1020 which is oxygen-free copper, alloy numbers C1220 and C1201 which are phosphor deoxidized copper and the like are used.

In general, the specifications of the refrigerant piping need to comply with the technical standards stipulated in the High Pressure Gas Safety Act, the Refrigeration Safety Regulations, and the Refrigeration Safety Regulations-related example standards. Generally, the pressure resistance type and the minimum wall thickness of the refrigerant pipe are selected from the copper and copper alloy pipes for the refrigerant pipe listed in the appendix of JIS B 8607: 2020.

It has been confirmed that the copper constituting the conventional refrigerant pipe produces CuI on the inner surface of the copper pipe by the reaction of _{CF 3} I when a mixed refrigerant containing _{CF 3 I is used.} Copper may not only react with hydrogen iodide, etc. generated by the reaction of _{CF 3} I with water, etc., but also react directly _{with CF 3 I itself on the metal surface.}

It has been confirmed that the amount of CuI produced is large in the section of the copper pipe in the refrigerant circuit where the refrigerant has a high temperature of about 70 ° C. or higher. In particular, it is remarkably large in the refrigerant pipe connected to the discharge side of the compressor, and the section between the compressor and the four-way valve is the main source. It has been confirmed that CuI forms granules and sludge in the form of adhering to the inner surface of the copper tube, peels off from the inner surface of the copper tube, circulates in the refrigerant circuit, and accumulates in a narrow place in the refrigerant circuit. There is.

For example, when CuI flows into a valve body such as a four-way valve or an expansion valve, the flow path may be clogged or the sliding portion of the valve body or valve stem may be caught, resulting in malfunction. It becomes a factor. In addition, the closed compressor is equipped with a refueling pump in the shaft and around the crank, but when CuI flows into the compressor, it accumulates in the flow path of the refueling pump or in the refueling pocket, etc., due to insufficient refueling. Causes malfunction.

Further, the CuI granules and sludge may contain not only CuI but also organic components and secondary reaction products such as metal soap. Secondary reaction products include CF ₃ I itself, _{reaction products generated by the reaction of CF 3} I, organic materials such as refrigerating machine oil and sealing materials in refrigerant circuits, and metals derived from metal materials. There can be reaction products with ions and the like.

Generation of CuI and secondary reaction products, not only increase the likelihood of malfunction of the device, CF 3 _I deterioration of decomposition or refrigerant which means that in progress. As _{the decomposition of CF 3} I progresses, it is feared that the flame retardancy of the refrigerant will deteriorate and the GWP will increase due to the production of trifluoromethane (HFC23) and the like. In addition, there is a concern that CuI and secondary reaction products may be compounded, and sludge accumulation and clogging may easily occur.

In addition, the copper constituting the conventional refrigerant pipe _{may react directly with the CF 3} I itself, and may actively promote the deterioration of the refrigerant itself. The copper metal surface constituting the refrigerant pipe may act catalytically on _{CF 3 I and the like without being ionized.} In such a case, even if the amount of water in the refrigerant circuit is reduced, there is a concern that the decomposition of _{CF 3 I itself will proceed, including the location where the refrigerant becomes hot.}

In response to such problems caused by the use of copper pipes, if a metal pipe having a low copper content is used as the refrigerant pipe in the section where the refrigerant reaches a high temperature of 70 ° C. or higher during the operation of the refrigeration cycle, CuI or secondary Since the formation of the reaction product is suppressed, it is possible to prevent CuI and the secondary reaction product from sticking to and accumulating on the valve, the refueling pump and the like. In addition, since _{the direct reaction between the copper tube and CF 3} I is reduced, it is considered that the deterioration of the refrigerant itself can be suppressed. Therefore, CF 3 despite a mixed refrigerant containing _I, is suppressed deterioration of the refrigerant, and reduces the production of CuI caused by the reaction of the refrigerant, and various valves, the operation failure of equipment such as oil supply pump A refrigeration cycle device with high energy efficiency and operational reliability that can be prevented over a long period of time can be obtained.

Specific examples of the valve include a four-way valve, an outdoor expansion valve, an overcooling expansion valve that sends the overcooling refrigerant to a heat exchanger that exchanges heat with the overcooling refrigerant, a discharge pipe of the compressor, and the like built into the compressor. Check valve, overcooling bypass check valve provided in the bypass circuit that bypasses the overcooled refrigerant generated in the condenser toward the compressor, indoor expansion valve, safety valve in the refrigerant circuit, switching valve provided in the multi air conditioner, etc. Can be mentioned. Examples of the refueling pump include a refueling slit that raises oil by using a pressure difference, and a pump having various mechanisms such as a screw pump and a gear pump.

The refrigeration cycle device using a metal tube having a low copper content is not particularly limited in the type of device such as a multi air conditioner for buildings, a room air conditioner, a package air conditioner, etc., but is preferably a large air conditioner. , It is particularly preferable that the multi air conditioner for a building is provided with a plurality of indoor units.

A large air conditioner has a large amount of refrigerant filled, the length of the refrigerant pipe is long, and the compressor may be parallelized. In such an air conditioner, if a _{mixed refrigerant containing CF 3} I is used and a copper pipe is used as a refrigerant pipe in a section where the refrigerant becomes hot during the operation of the refrigeration cycle, a large amount of Cu I is generated. When there is a place in the refrigerant circuit where insoluble substances are likely to accumulate, a large amount of CuI is concentrated in that place, so that malfunction of the device or the like is likely to occur.

On the other hand, in a large air conditioner, if a metal pipe having a low copper content is used as the refrigerant pipe in the section where the refrigerant reaches a high temperature of about 70 ° C. or higher during the operation of the refrigeration cycle, CuI in the refrigerant circuit can be used. Since the amount of production is greatly reduced, it is effective in that it is possible to prevent malfunction of the device due to concentration of a large amount of CuI.

In the metal pipe having a low copper content used in the section where the refrigerant becomes hot, the Cu content of the material forming the pipe is less than 0.5% by mass, preferably 0.4% by mass or less, more preferably 0. .3% by mass or less, more preferably 0.2% by mass or less, still more preferably 0.1% by mass or less. If the amount of Cu is less than about 0.5% by mass, the generation of CuI and the deterioration of the refrigerant itself are sufficiently suppressed even in a place where the temperature becomes high of about 70 ° C. or higher during the operation of the refrigeration cycle. Can be used appropriately.

As metal pipes having a low copper content, steel pipes, stainless steel pipes, aluminum pipes, aluminum alloy pipes, etc. having a Cu content of at least 0.5% by mass are used for each material according to the pressure resistance required for the refrigerant pipe. Moreover, it is used as a dimension that satisfies the minimum wall thickness for each outer diameter. These metal pipes may be either extruded pipes or drawn pipes. Further, surface treatment such as plating and anodic oxidation treatment and coating such as rust preventive coating may be applied. However, the inner surface of the pipe does not have to be coated.

As the steel pipe, a carbon steel pipe for pressure piping specified in JIS G 3454: 2017 is preferable. Preferred materials for steel pipes include STPG370 and STPG410, which have a Cu content of 0.5% by mass or less.

STPG370 is C: 0.25% or less, Si: 0.35% or less, Mn: 0.30 to 0.90%, P: 0.040% or less, S: 0.040% or less, in mass%. tensile strength: 370N / mm ² or more, proof stress: 215 N / mm ² or more, elongation: at 16-30% or more depending on the specimen.

STPG410 has C: 0.30% or less, Si: 0.35% or less, Mn: 0.30 to 1.00%, P: 0.040% or less, S: 0.040% or less, in mass%. Tensile strength: 410 N / mm ² or more, proof stress: 245 N / mm ² or more, elongation: 11 to 25% or more depending on the test piece.

As the stainless steel pipe, the stainless steel pipe for piping specified in JIS G 3459: 2016 is preferable. Preferred materials for the stainless steel pipe include SUS304 and SUS316 having a Cu content of 0.5% by mass or less.

SUS304 is C: 0.08% or less (H: 0.04 to 0.10%, L: 0.030% or less), Si: 1.00% or less (H: 0.75% or less) in mass%. ), Mn: 2.00% or less, P: 0.045% or less (H: 0.040% or less), S: 0.030% or less, Ni: 8.00 to 11.00% (L: 9. 00~13.00%), Cr: 18.00~20.00% , tensile strength: 520N / mm ² or more (L: 480N / mm ² or more), strength: 205N / mm ² or more (L: 175 N / mm ² or more), elongation: 22 to 35% or more depending on the test piece.

SUS316 is C: 0.08% or less (H: 0.04 to 0.10%, L: 0.030% or less), Si: 1.00% or less (H: 0.75% or less) in mass%. ), Mn: 2.00% or less, P: 0.045% or less (H: 0.030% or less), S: 0.030% or less, Ni: 10.00 to 14.00% (H: 11. 00 to 14.00%, L: 12.00 to 16.00%), Cr: 16.0 to 18.00%, tensile strength: 520 N / mm ² or more (L: 480 N / mm ² or more), proof stress : 205 N / mm ² or more (L: 175 N / mm ² or more), Elongation: 22 to 35% or more depending on the test piece.

As the aluminum tube and the aluminum alloy tube, the aluminum and aluminum alloy seamless tube specified in JIS H 4080: 2015 is preferable. Preferred materials for the aluminum alloy tube include A1070, A1100, A3003, A3004, A3005, A3103, A6061, A6063 and the like having a Cu content of 0.5% by mass or less.

A1070 is Si: 0.20% or less, Fe: 0.25% or less, Cu: 0.04% or less, Mn: 0.03% or less, Mg: 0.03% or less, Zn: 0 in mass%. .04% or less, V: 0.05% or less, Ti: 0.03% or less, other elements: 0.03% or less individually, tensile strength of extrusion pipe: 55N / mm ² or more, strength of extrusion pipe : 15N / mm ² or more, the tensile strength of the drawn tube: is in accordance with the temper 55N / mm ² or more 95N / mm ² or less ~120N / mm ² or more.

A1100 is Si + Fe: 0.95% or less, Cu: 0.05 to 0.20%, Mn: 0.05% or less, Zn: 0.10% or less, and other elements: 0. 05% or less, 0.15% or less in total, tensile strength of extruded pipe: 75 N / mm ² or more, strength of extruded pipe: 20 N / mm ² or more, elongation of extruded pipe: 25% or more, tensile strength of drawn pipe is: is in accordance with the temper 75N / mm ² or more 110N / mm ² or less ~155N / mm ² or more.

A3003 is Si: 0.6% or less, Fe: 0.7% or less, Cu: 0.05 to 0.20%, Mn: 1.0 to 1.5%, Zn: 0.10 in mass%. % Or less, V: 0.05% or less, other elements: 0.03% or less individually, 0.15% or less in total, tensile strength of extrusion pipe: 95N / mm ² or more, strength of extrusion pipe: 35N / mm ² or more, the tensile strength of the drawn tube: according to temper 95N / mm ² or more 125N / mm ² or less ～185N / mm ² or more, strength of drawn tube: according to temper 35N / mm ² or more ～165N / mm ² or more, elongation of drawn tube: 30% or more to 2% or more depending on the quality.

A3103 is in mass%, Si: 0.50% or less, Fe: 0.7% or less, Cu: 0.10% or less, Mn: 0.9 to 1.5%, Mg: 0.30% or less, Cr: 0.10% or less, Zn: 0.20% or less, Zr + Ti: 0.10% or less, Other elements: 0.05% or less individually, 0.15% or less in total, tensile strength of extrusion pipe : depending on the temper 95N / mm ² or more ~95N / mm ² or more 125N / mm ² or less, the extruded tube strength: 35N / mm ² or more, elongation of the extruded tube: 20% or more, tensile strength of the drawn tube: quality separately accordance with 95N / mm ² or more ~95N / mm ² or more 125N / mm ² or less, strength of drawn tube: according to temper 35N / mm ² or more ~165N / mm ² or more, elongation of the drawn tube: according to temper It is 30% or more to 2% or more.

A6061 is Si: 0.40 to 0.8%, Fe: 0.7% or less, Cu: 0.15 to 0.40%, Mn: 0.15% or less, Mg: 0.8 in mass%. ~ 1.2%, Cr: 0.04 to 0.35%, Zn: 0.25% or less, Ti: 0.15% or less, Other elements: 0.05% or less individually, 0.15 in total % or less, tensile strength of the extruded tube: according to temper 145N / mm ² or less ~265N / mm ² or more, proof stress of the extruded tube: according to temper 110N / mm ² or less ~245N / mm ² or more, the extruded tube elongation: 16% or more to 8% or more, tensile strength of the drawn tube: according to temper 145N / mm ² or less ~295N / mm ² or more, strength of drawn tube: according to different quality 100 N / mm ² or less ～245N / mm ² or more, elongation of drawn tube: 20% or more to 10% or more depending on the quality.

A6063 is Si: 0.25 to 0.6%, Fe: 0.35% or less, Cu: 0.10% or less, Mn: 0.10% or less, Mg: 0.45-0. 9%, Cr: 0.10% or less, Zn: 0.10% or less, Ti: 0.10% or less, Other elements: 0.05% or less individually, 0.15% or less in total, extruded pipe tensile strength: according to temper 135N / mm ² or less ~245N / mm ² or more, proof stress of the extruded tube: according to temper 60N / mm ² or less ~200N / mm ² or more, elongation of the extruded tube: 16% or more and 8% or more, tensile strength of the drawn tube: according to temper 125N / mm ² or less ~275N / mm ² or more, strength of drawn tube: according to temper 75N / mm ² or more ~240N / mm ² or more, drawn tube Growth: 16% or more to 5% or more depending on the quality.

As the material of the aluminum alloy tube, A2011, A2014, A4032, A7075 and the like are not preferable in that the amount of Cu is 0.5% by mass or more. Aluminum pipes and aluminum alloy pipes have lower mechanical strength than copper pipes, so the wall thickness of the pipes must be increased.

When a metal pipe with a low copper content is used as a pressure pipe that receives pressure on the inner surface, it must be at least the minimum thickness required by the following correction formula (I) (Freezing Safety Regulations-related Example Standard 23.6). See .1).
t = P ・ Do / (2 ・ σa ・ η + 0.8P) ・ ・ ・ (I)
Here, t: minimum thickness of pipe (mm), P: design pressure (MPa), Do: outer diameter of pipe (mm), σa: allowable tensile stress of material (N / mm ² ), η: welded joint Represents the efficiency of.

Metallic tubes with a low copper content are preferably used at least in the section between the compressor and the four-way valve. The section between the compressor and the four-way valve is a section in which CuI is likely to be generated because the temperature of the refrigerant is 70 ° C. or higher. Therefore, if a metal pipe having a low copper content is used as the refrigerant pipe in such a section, the amount of CuI generated in the refrigerant circuit can be effectively reduced. A U-shaped trap for preventing backflow and a curved portion for suppressing vibration may be formed in the metal tube having a low copper content.

When an oil separator is provided between the compressor and the four-way valve, the metal pipe having a low copper content is preferably used at least for the refrigerant pipe connecting the compressor and the oil separator, and the compressor and oil are used. It is more preferable to use it for both the refrigerant pipe connecting the separator and the refrigerant pipe connecting the oil separator and the four-way valve. Further, when a flexible pipe such as a metal bellows is provided on the discharge side of the compressor in order to prevent vibration, liquid hammer, noise, etc., it is preferable to use it for the refrigerant pipe connected to the flexible pipe.

Metallic tubes with a low copper content may be used in other sections of the refrigerant circuit in addition to the section between the compressor and the four-way valve. Specific examples of other sections in the refrigerant circuit include a section between the four-way valve and the outdoor heat exchanger, a section between the four-way valve and the indoor heat exchanger, and the like. However, from the viewpoint of mechanical strength, high workability, low material cost, etc., these sections and the section between the outdoor heat exchanger and the indoor heat exchanger are composed of copper pipes. Is preferable.

The four-way valve may be made of brass, stainless steel, or the like. The connection between a metal pipe with a low copper content and the discharge side of a four-way valve or compressor is brazing or fusion welding using silver brazing, copper brazing, brass brazing, nickel brazing, aluminum brazing, etc., depending on the material. , Eutectic pressure welding or the like. A joint can be used on the discharge side of the compressor or the like in order to prevent contact between dissimilar metals, fatigue fracture due to vibration, and the like.

According to the refrigeration cycle apparatus according to the present embodiment described above, since a metal pipe having a low copper content is used as the refrigerant pipe in the section where the refrigerant becomes high temperature of about 70 ° C. or higher during the operation of the refrigeration cycle, CF ₃ I is used. Despite the use of the mixed refrigerant containing the mixture, the amount of CuI, organic components, metal soap and the like produced is reduced, and malfunction of the equipment due to clogging and the like is prevented for a long period of time. Since the direct reaction between copper and CF 3 _I itself is suppressed, a long period of time that exceeds the operation time corresponding to accelerated aging tests of 504 hours at 50 to 150 ° C., a total acid number of refrigerating machine oil 0 It can be kept below 1 mgKOH / g. Further, such a low total acid value may act in a direction of reducing the reaction between the copper tube and hydrogen iodide when the copper tube is used in the section where the refrigerant is at a low temperature. Therefore, it is possible to provide a refrigeration cycle apparatus having high energy efficiency and operational reliability using a mixed refrigerant containing _{CF 3} I, which has both low GWP and low combustibility.

Although the embodiment of the refrigeration cycle apparatus according to the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are included as long as it does not deviate from the technical scope. For example, the above embodiment is not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of a certain embodiment with another configuration, or to add another configuration to the configuration of a certain embodiment. It is also possible to add, delete, or replace some of the configurations of one embodiment.

Hereinafter, the present invention will be specifically described with reference to examples, but the technical scope of the present invention is not limited thereto.

<Tests 1-35>
An accelerated deterioration test by heating using an autoclave was conducted to evaluate the tendency of metal iodide formation for the combination of the mixed refrigerant containing trifluoroiodomethane (CF _{3 I), refrigerating machine oil, and the pipe material of the refrigerant piping.} rice field.

The refrigerant, assuming a multi-air conditioner for buildings _{HFC32: HFC125: CF 3 I =} 50 wt%: 10 wt%: with 40 wt% of the mixed refrigerant.

For tests 1 to 15, the following polyol ester oil (symbol POE) was used as the refrigerating machine oil. Each refrigerating machine oil contained 0.25% by weight of DBPC (2,6-di-t-butyl-p-cresol), which is an antioxidant. Further, 0.5% by weight of CGE (3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate), which is an alicyclic epoxy compound, was blended.

(Symbol POE) Hindered type polyol ester oil (pentaerythritol-based mixed fatty acid ester oil of 2-ethylhexanoic acid / 3,5,5-trimethylhexanoic acid, kinematic viscosity at 40 ° C. = 64.9 mm ² / s)

For tests 16 to 20, a polyol ester oil base oil (symbol POE-B) containing no additives was used as the refrigerating machine oil.

For tests 21 to 35, the following polyvinyl ether oil (symbol PVE) was used as the refrigerating machine oil. Each refrigerating machine oil contained 0.3% by weight of DBPC (2,6-di-t-butyl-p-cresol), which is an antioxidant. Further, an epoxy-based acid scavenger was blended in an amount of 0.3% by weight. Further, 1.0% by weight of TCP (tricresyl phosphate), which is an extreme pressure agent, was blended.

(Symbol PVE) Polyvinyl ether oil (polymer of alkoxyvinyl, copolymer ether oil in which the alkoxy group is ethyloxy group and isobutyloxy group, kinematic viscosity at 40 ° C. = 66.8 mm ² / s)

(Accelerated aging test using autoclave)
The accelerated deterioration test was carried out according to the following procedure. First, a container made of polytetrafluoroethylene (PTFE) was placed in a washed autoclave (pressure resistance: maximum 20 MPa, internal volume: 220 mL). Then, 24 g of refrigerating machine oil and a metal tube (outer diameter: 6.35 mm, wall thickness: 1.2 mm, length: 50 mm) were placed in this PTFE container.

The material of the metal tube was copper (phosphorylated copper: C1220), stainless steel (austenitic stainless steel: SUS304), and aluminum alloy (manganese-added aluminum alloy: A3005). Two metal tubes were placed in each PTFE container prepared for each refrigerating machine oil. The refrigerating machine oil adjusted the initial water content to less than 100 ppm by weight. The water content of the refrigerating machine oil was measured by the Carl Fischer type coulometric titration method according to JIS K 2275-3.

Subsequently, an autoclave containing a refrigerating machine oil and a metal tube in a PTFE container was depressurized to 100 Pa or less and evacuated, and then 12 g of a refrigerant was introduced to seal the autoclave. Then, this autoclave was placed in a constant temperature bath and heated. The heating time was 504 hours. The heating temperature was any of 50 ° C., 75 ° C., 100 ° C., 125 ° C., and 150 ° C. 75 to 125 ° C. corresponds to the high temperature range in the actual machine. After heating, the PTFE container was opened, and the total acid value and hue of the refrigerating machine oil and the weight change of the metal tube were measured.

The total acid value was measured according to JIS K 2501: 2003 "Petroleum products and lubricating oil-neutralization value test method". Hue was tested in ASTM color according to JIS K 2580: 2003 "Petroleum products-color test method". The weight change of the metal tube was determined as the amount of weight change per ^{unit area (m 2} ) of the surface area by measuring the increase in weight as compared with that before the test. It can be said that the increase in weight represents the total weight of the product due to the reaction of the metal tube, the product due to the reaction of the refrigerant and the refrigerating machine oil, and the like.

FIG. 3 is a scanning electron microscope image of the surface of the metal tube after the accelerated deterioration test at 150 ° C.
In FIG. 3, in _{the presence of a mixed refrigerant containing CF 3} I and refrigerating machine oil, a metal tube is heated to a high temperature of 150 ° C. for accelerated deterioration, and then the surface of the metal tube is subjected to a scanning electron microscope (Scanning Electron Microscope). The result observed by SEM) is shown. As shown in FIG. 3, in the case of the copper tube, fine granular products were observed on the surface. On the other hand, in the case of stainless steel pipes and aluminum alloy pipes, almost no products were observed.

Subsequently, the surface of the metal tube was elementally analyzed by SEM-EDX (Energy Dispersive X-ray Spectroscopy). As a result, the chemical composition of the product produced in the copper tube was carbon C: 4.6% by mass, iodine I: 61.7% by mass, and copper Cu: 33.7% by mass. From the molar ratio of iodine to copper, the product produced in the copper tube is copper iodide (CuI), and it is presumed that it contains organic components and the like. On the other hand, in the case of stainless steel pipes and aluminum alloy pipes, halogens such as iodine were not detected.

Tables 1 and 2 show the measurement results of the hue of the refrigerating machine oil, the total acid value of the refrigerating machine oil, and the weight change of the metal tube for tests 1 to 35.

Tests 1 to 15 used polyol ester oil to which an additive was added as the refrigerating machine oil, but the total acid value of the refrigerating machine oil after the test was relative to the initial value (0.01 mgKOH / g or less). It is suppressed to a small increase. The total acid value is 0.1 mgKOH / g or less in the case of all temperatures and pipe materials, and the deterioration of refrigerating machine oil is sufficiently suppressed.

The weight change of metal pipes was the largest in the case of copper pipes, followed by aluminum alloy pipes and stainless steel pipes. The weight change of the metal tube tends to be larger as the temperature is higher. It can be seen that the amount of metal iodide and the like produced is large in the case of copper tubes, and increases as the temperature rises. In the case of the copper tube, ^{a large weight change of 0.5 g / m 2} or more occurred at 75 to 150 ° C., whereas a small weight change occurred at 50 ° C.

From these results, it can be seen that the stainless steel pipe and the aluminum alloy pipe can suppress the formation of metal halides such as metal iodide even in the high temperature refrigerant pipe. Further, even if it is a conventional copper pipe, if the temperature is lower than about 75 ° C., the production of copper iodide is suppressed, so that it can be used as a refrigerant pipe in a place where the temperature does not become high during the operation of the refrigeration cycle. I can say.

In Tests 16 to 20, the base oil of the polyol ester oil containing no additive was used as the refrigerating machine oil, but the total acid value of the refrigerating machine oil after the test was significantly higher than that in Tests 1 to 15. Is increasing. The weight change of the metal tube also occurs at a low temperature of 50 ° C. Even when polyol ester oil is used as the refrigerating machine oil, if appropriate additives are not added, the total acid value should be kept at 0.1 mgKOH / g or less, and the amount of metal iodide produced. It can be said that it is difficult to keep the amount below 0.5 g / m ^2.

In tests 21 to 35, polyvinyl ether oil was used as the refrigerating machine oil, but the total acid value of the refrigerating machine oil after the test tended to be higher than that in tests 1 to 15. In particular, in the case of a copper tube, the total acid value is significantly increased to 0.1 mgKOH / g or more. The weight change of the metal tube tends to be large as compared with Tests 1 to 15.

In particular, as shown in Tests 21 to 25, in the case of the copper tube, the total acid value increased remarkably to 0.1 mgKOH / g or more even at a low temperature of 50 ° C., and the weight change of the metal tube. Is also significantly larger. At 75 to 150 ° C., the total acid value and weight change are further increased. From these results, it can be seen that polyvinyl ether oil is not preferable in the refrigerant circuit using the copper tube.

Further, as shown in Tests 26 to 30, in the case of the stainless steel pipe, the total acid value is suppressed at 50 to 100 ° C., and the weight change of the metal pipe is also small. However, at a temperature higher than 100 ° C., the total acid value slightly increases and the weight change of the metal tube ^{becomes large to 0.5 g / m 2} or more. When polyvinyl ether oil is used, even stainless steel pipes do not provide sufficient countermeasures, and it can be seen that polyol ester oil is preferable.

Further, as shown in Tests 31 to 35, in the case of the aluminum alloy pipe, the total acid value is suppressed at 50 to 75 ° C., and the weight change of the metal pipe is also small. However, at a temperature higher than 75 ° C., the total acid value increases and the weight change of the metal pipe becomes larger than in the case of the stainless steel pipe. When polyvinyl ether oil is used, even aluminum alloy pipes do not provide sufficient countermeasures and may react more than stainless steel pipes, indicating that polyol ester oil is preferable.

<Example 1>
In the refrigeration cycle device shown in FIG. 1, the refrigerant pipe between the compressor and the four-way valve is changed to a stainless steel pipe (material: SUS304, outer diameter: 15.88 mm, wall thickness: 1.0 mm) to achieve high speed and high load. A 3000 hour endurance test was performed under the conditions.

As the refrigeration cycle device, a device equipped with a scroll-type sealed electric compressor and having a cooling capacity of 28 kW was used for a multi air conditioner for buildings. The rotation speed of the compressor was set to 6000 min ^-1 . A heat-resistant PET film (class B, temperature index: 130 ° C.) having a thickness of 250 μm was used to insulate the iron core of the motor from the coil. For the coil, a double-coated copper wire coated with a double coat of polyesterimide-amideimide was used.

The refrigerant, in the same manner as in Test 1 to 35, assuming a multi-air conditioner for buildings _{HFC32: HFC125: CF 3 I =} 50 wt%: 10 wt%: with 40 wt% of the mixed refrigerant. As the refrigerant, 8000 g was sealed in the refrigerant circuit. As the refrigerating machine oil, as in Tests 1 to 15, a polyol ester oil to which an additive was added was used, and 1500 mL was sealed in the compressor.

<Comparative example 1>
In the refrigeration cycle device shown in FIG. 1, the refrigerant pipe between the compressor and the four-way valve is configured with a conventional copper pipe (material: C1220, outer diameter: 15.88 mm, wall thickness: 1.2 mm). Similar to Example 1, a 3000 hour endurance test was carried out under high speed and high load conditions.

(An endurance test)
The refrigeration cycle apparatus according to Example 1 and the refrigeration cycle apparatus according to Comparative Example 1 were operated for 3000 hours. After that, the refrigerant pipe between the compressor and the four-way valve was cut to cut out the inner surface, and the state of formation and adhesion of deterioration products was observed with a scanning electron microscope.

FIG. 4 is a scanning electron microscope image of the surface of the refrigerant pipe connected to the discharge side of the compressor after the durability test.
As shown in FIG. 4, in Example 1 in which the refrigerant pipe between the compressor and the four-way valve was a stainless steel pipe, almost no product was observed on the inner surface of the stainless steel pipe after the durability test. On the other hand, in Comparative Example 1 in which the refrigerant pipe between the compressor and the four-way valve was a copper pipe, a large amount of product adhered to the inner surface of the copper pipe after the durability test.

In Example 1, which is a stainless steel pipe, when the inner surface of the refrigerant pipe after the durability test was elementally analyzed by SEM-EDX, halogen such as iodine was not detected. Further, when the outdoor expansion valve and the indoor expansion valve of the outdoor heat exchanger after the durability test were disassembled and the state of adhesion of foreign matter was observed, no foreign matter was observed in any of the expansion valves. In addition, no valve seat leakage occurred in any of the expansion valves, and the operating voltage was within the standard range. Only a small amount of deposits such as copper iodide was present at the suction port of the refueling pump of the compressor.

On the other hand, in Comparative Example 1 which is a copper pipe, the outdoor expansion valve and the indoor expansion valve of the outdoor heat exchanger after the durability test were disassembled, and the state of adhesion of foreign matter was observed. A large amount of foreign matter was found to adhere to the surrounding area. Further, in the outdoor expansion valve of the outdoor heat exchanger, valve seat leakage occurred, and in the indoor expansion valve, the operating voltage was out of the standard range. A large amount of deposits such as copper iodide was found at the bottom of the refueling pump case where the suction port of the refueling pump of the compressor is located.

_{From the above results, regarding a refrigeration cycle device that uses a mixed refrigerant containing CF 3} I that has both low GWP and low flammability, the copper content is high as the refrigerant piping in the section where the refrigerant becomes hot during the operation of the refrigeration cycle. It was confirmed that the use of a low metal pipe reduces deposits and deposits on equipment such as valves and refueling pumps, and prevents malfunction of these equipment for a long period of time.

1 Outdoor unit 2 Indoor unit 3 Compressor 4 Four-way valve 5 Outdoor heat exchanger (condenser / evaporator)
6 Receiver tank 7 Dryer 8 Outdoor expansion valve (decompressor)
9 Accumulator 10 Outdoor blower 11 Indoor heat exchanger (evaporator / condenser)
12 Indoor expansion valve (decompressor)
13 Indoor blower 20 Fixed scroll member 20a Fixed lap 21 Swivel scroll member 21a Swivel lap 22 Frame 23 Crankshaft 24 Motor 25 Sealed container 26 Compression chamber 27 Discharge port 28 Discharge pipe 29 Oil hole 30 Main bearing 31 Sub-bearing 32 Oil reservoir 110 Suction pipe 120 Discharge pipe 130 Refrigerator pipe 140 Refrigerator pipe 150 Refrigerator pipe 160 Refrigerator pipe

Claims (1)

A compressor that compresses the refrigerant, a four-way valve that switches the circulation direction of the refrigerant compressed by the compressor, a condenser that condenses the refrigerant flowing from the four-way valve, and a depressurization that depressurizes the refrigerant condensed by the condenser. A refrigeration cycle device including a device and an evaporator for evaporating the refrigerant decompressed by the decompressor.
The refrigerant is a mixed refrigerant containing trifluoroiodomethane, and has a vapor pressure of 1.1 MPa or more and 1.8 MPa or less at 25 ° C.
The compressor is a closed electric compressor in which a compression mechanism portion and a motor for driving the compression mechanism portion are provided in a closed container, and refrigerating machine oil for lubricating the sliding portion is filled. ,
The refrigerating machine oil is a polyol ester oil having a total acid value of 0.1 mgKOH / g or less.
A stainless steel pipe having a Cu amount of less than 0.5% by mass in the refrigerant pipe connecting the compressor and the four-way valve, which is a section where the refrigerant becomes hot at 70 ° C. or higher during the operation of the refrigeration cycle. aluminum alloy tube der aluminum tube or Cu content Cu content is less than 0.5 mass% is less than 0.5 wt% is,
A refrigeration cycle device in which the refrigerant pipe connecting the condenser and the evaporator is a copper pipe.

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