JP6759017B2 - How to manage an air conditioner - Google Patents

Description

The present invention relates to an air conditioner, and more particularly to an air conditioner using a refrigerant containing a hydrofluoroolefin.

In an air conditioner using a refrigeration cycle system consisting of a compressor, a condenser, an expansion mechanism, an evaporator, etc., it is a big problem to reduce the global warming potential (GWP value) of the refrigerant used in the air conditioner. It has become. In particular, the currently used "R410A" has an ozone depletion potential of "0" but still has a high GWP value, and according to the Fifth Assessment Report of the "United Nations Intergovernmental Panel on Climate Change" (IPCC), the GWP value is about. It is as high as 1924.

As a countermeasure, it is known that the GWP value can be lowered by using a hydrofluoroolefin (hereinafter referred to as HFO) -based refrigerant having a double bond in the refrigerant molecule. For example, "HFO1234yf" has a GWP value of about "1" in the IPCC 5th report, and it is possible to significantly reduce the GWP value of the refrigerant used in the air conditioner. When actually used in an air conditioner, the HFO-based refrigerant has a characteristic of high evaporation temperature and low pressure, so that it is mixed with a high-pressure refrigerant such as "R410A" or "R32". It is used as a refrigerant.

As an air conditioner using an HFO-based refrigerant as the refrigerant, for example, an air conditioner shown in JP-A-2010-203759 (Patent Document 1) is known. Patent Document 1 proposes the use of an ester-based refrigerating machine oil containing an HFO-based refrigerant and an unsaturated fatty acid as constituent fatty acids. Then, in Patent Document 1, the unsaturated fatty acid residue in the refrigerating machine oil is reacted with hydrogen fluoride, which is a refrigerant decomposition product, to remove hydrogen fluoride in the refrigerating cycle system, and the constituent parts of the refrigerating cycle system are used. It states that deterioration can be suppressed.

JP-A-2010-203759

By the way, in a multi-type air conditioner for buildings where the length of the refrigerant pipe from the outdoor unit is long and a plurality of indoor units are used, the volume of each component including the length of the refrigerant pipe of the refrigeration cycle system is large, and the refrigeration cycle is performed during construction. Even if so-called vacuuming (vacuum degree control) is performed to reduce the pressure (vacuum degree) in the system to a predetermined value or less, there is a high possibility that a predetermined amount or more of air will remain as a whole. That is, even if the degree of vacuum is controlled, if the volume of the refrigeration cycle system is large, the total amount of remaining air increases.

Then, in Patent Document 1, an ester oil containing an unsaturated fatty acid as a constituent fatty acid is used, but even if the pressure in the refrigeration cycle system is controlled to a predetermined value or less at the time of construction, the degree of vacuum is controlled. Since a predetermined amount or more of air remains in the refrigeration cycle system, the ester oil may be hydrolyzed to raw material fatty acids and alcohols due to the moisture contained in the remaining air. In the presence of water, this hydrolysis can also occur in polyol ester oils (hereinafter, POE oils) often used as refrigerating machine oils, including ester oils containing unsaturated fatty acids described in Patent Document 1 as constituent fatty acids. The acid generated by hydrolysis deteriorates the refrigeration cycle system and raises the total acid value of the refrigerating machine oil. In particular, corrosion occurs on the sliding parts of the compressor that composes the refrigeration cycle system, and the reliability of the refrigeration cycle is increased. May be damaged early.

Similarly, in an air conditioner that uses an HFO-based refrigerant as the refrigerant and polyvinyl ether oil (hereinafter referred to as PVE oil) as the refrigerating machine oil, a predetermined amount or more of air is present during the refrigeration cycle. In such an environment, the deterioration of the refrigerant and PVE oil due to oxygen in the air progresses, the total acid value of the refrigerating machine oil rises, and the sliding parts of the compressor that compose the refrigerating cycle are corroded, resulting in the refrigeration cycle. There is a risk of premature loss of reliability.

As described above, oxygen and moisture in the air remaining in the refrigeration cycle system adversely affect the refrigeration cycle system using the HFO-based refrigerant and the refrigerating machine oil. Even if the degree of vacuum is controlled and the degree of vacuum is adjusted to a predetermined value, the total amount of air remaining in the refrigeration cycle system differs depending on the configuration of the refrigeration cycle system (for example, the length of the refrigerant pipe and the number of indoor units). It is a thing.

In particular, in multi-type air conditioners for buildings where many indoor units are installed and require a large air conditioning capacity, recently, one outdoor unit with a large capacity does not cover all the air conditioning load, but multiple units. In many cases, the outdoor unit is connected to the refrigeration cycle system of the same refrigerant to cover the air conditioning load. Since compressors are mounted on each of the multiple outdoor units, the relationship between the amount of refrigerating machine oil held in the refrigeration cycle system and the amount of air mixed during construction depends on the length of the refrigerant piping and the components of the refrigeration cycle. It is different for each harmonizer.

As can be seen from the above explanation, the method of setting the degree of vacuum to a predetermined value or less by controlling the degree of vacuum cannot control the total amount of residual air, and the refrigerating machine oil of the refrigerating cycle system using the HFO-based refrigerant cannot be controlled. It is not suitable for suppressing deterioration due to oxidation and the like, and it is important to control at least the amount of residual air in the refrigerating machine oil.

An object of the present invention is to provide a novel air conditioner that controls the allowable residual air amount for a refrigerating machine oil of a refrigerating cycle system using an HFO-based refrigerant and suppresses oxidative deterioration of the refrigerating machine oil of the refrigerating cycle system. is there.

A feature of the present invention is that in a refrigerating cycle system in which a refrigerant containing 20 wt% or more of an HFO-based refrigerant and refrigerating machine oil are sealed, the amount of air N [mol / g] remaining in the refrigerating cycle system with respect to 1 g of refrigerating machine oil determines the refrigerant piping length. When Xp [m] is set, the value is controlled so as not to exceed the air amount N [mol / g] determined by N = (4.0 × ^10-7 ) and Xp + (4.0 × ^10-6 ). There is.

According to the present invention, the GWP value can be lowered, the oxidative deterioration of the refrigerating machine oil can be suppressed, and the reliability of the refrigerating cycle system can be ensured for a long period of time.

It is a block diagram explaining the refrigerating cycle system of an air conditioner. It is sectional drawing which shows the structure of the scroll compressor shown in FIG. It is explanatory drawing which shows the GWP value of a refrigerant. It is explanatory drawing which shows the relationship between the amount of air per 1 g of refrigerating machine oil and the degree of deterioration of refrigerating machine oil. It is explanatory drawing explaining the relationship between the refrigerant pipe length of the air conditioner which uses HFO-based refrigerant, and the amount of air remaining in a refrigerating cycle system per 1 g of refrigerating machine oil.

The embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments, and various modifications and applications thereof are also included in the technical concept of the present invention. It is included in the range.

FIG. 1 shows a refrigeration cycle system of an air conditioner to which the present invention is applied. The outdoor unit 10 and the indoor unit 30 are connected by a gas connection pipe 11 and a liquid connection pipe 12, respectively, and the refrigerant flows between the outdoor unit 10 and the indoor unit 30.

The outdoor unit 10 includes a compressor 13, a four-way valve 14, an outdoor heat exchanger 15, an outdoor blower 16, an outdoor expansion valve 17, an accumulator 18, a compressor suction pipe 19, and a gas refrigerant pipe 20. Have. The compressor 13 and the accumulator 18 are connected by a compressor suction pipe 19, and the four-way valve 14 and the accumulator 18 are connected by a gas refrigerant pipe 20.

The compressor 13 compresses the refrigerant and discharges it into the pipe. By switching the four-way valve 14, the flow of the refrigerant changes, and the cooling operation and the heating operation are switched. The outdoor heat exchanger 15 exchanges heat between the refrigerant and the outside air. The outdoor blower 16 supplies outside air to the outdoor heat exchanger 15. The outdoor expansion valve 17 depressurizes the refrigerant to a low temperature. The accumulator 18 is provided to store the liquid return at the time of transient, and adjusts the refrigerant to an appropriate degree of dryness.

The indoor unit 30 includes an indoor heat exchanger 31, an outdoor blower 32, and an indoor expansion valve 33. The indoor heat exchanger 31 exchanges heat between the refrigerant and the inside air. The outdoor blower 32 supplies outside air to the outdoor heat exchanger 31. The indoor expansion valve 33 can change the flow rate of the refrigerant flowing through the indoor heat exchanger 31 by changing the throttle amount thereof.

Although the indoor unit 30 is not shown, a plurality of indoor units 30 are connected to the outdoor unit 10 to form a multi-type air conditioner. An air conditioner having the above configuration is already well known.

Next, the cooling operation in the air conditioner will be described. The solid arrow in FIG. 1 indicates the flow of the refrigerant in the cooling operation of the air conditioner. In the cooling operation, as shown by the solid line, the four-way valve 14 communicates the discharge side of the compressor 13 with the outdoor heat exchanger 15, and communicates the accumulator 18 and the gas connection pipe 11.

Then, the high-temperature and high-pressure gas refrigerant compressed and discharged from the compressor 13 flows into the outdoor heat exchanger 15 via the four-way valve 14, is cooled by the outdoor air blown by the outdoor blower 16, and is condensed. Will be done. The condensed liquid refrigerant passes through the outdoor expansion valve 17 and the liquid connection pipe 12 and is sent to the indoor unit 30. The liquid refrigerant that has flowed into the indoor unit 30 is decompressed by the indoor expansion valve 33, becomes a low-pressure / low-temperature gas-liquid two-phase refrigerant, and flows into the indoor heat exchanger 31.

In the indoor heat exchanger 31, the gas-liquid two-phase liquid refrigerant is heated by the indoor air blown by the indoor blower 32 and evaporated to become a gas refrigerant. At this time, the indoor air is cooled by the latent heat of vaporization of the refrigerant, and cold air is sent into the room. After that, the gas refrigerant is returned to the outdoor unit 10 through the gas connection pipe 11.

The gas refrigerant returned to the outdoor unit 10 passes through the four-way valve 14 and the gas refrigerant pipe 20, and flows into the accumulator 18. A series of refrigeration cycles are formed by being adjusted to a predetermined degree of dryness by the accumulator 18, sucked into the compressor 13 via the compressor suction pipe 19, and compressed again by the compressor 13.

Next, the heating operation in the air conditioner 1 will be described. The dotted arrow in FIG. 1 indicates the flow of the refrigerant in the heating operation of the air conditioner. In the heating operation, the four-way valve 14 communicates the discharge side of the compressor 13 with the gas connection pipe 11 and communicates the accumulator 18 and the outdoor heat exchanger 15 as shown by the dotted line.

Then, the high-temperature and high-pressure gas refrigerant compressed and discharged from the compressor 13 passes through the gas connection pipe 11 and the four-way valve 14 and is sent to the indoor unit 30. The gas refrigerant that has flowed into the indoor unit 30 flows into the indoor heat exchanger 31, and the refrigerant is cooled and condensed by the indoor air blown by the indoor blower 32 to become a high-pressure liquid refrigerant. At this time, the indoor air is heated by the refrigerant and warm air is sent into the room. After that, the liquefied refrigerant passes through the indoor expansion valve 33 and the liquid connection pipe 12 and is returned to the outdoor unit 10.

The liquid refrigerant returned to the outdoor unit 10 is decompressed by a predetermined amount by the outdoor expansion valve 17, becomes a low-temperature gas-liquid two-phase state, and flows into the outdoor heat exchanger 15. The refrigerant flowing into the outdoor heat exchanger 15 exchanges heat with the outdoor air blown by the outdoor blower 16 to become a low-pressure gas refrigerant. The gas refrigerant flowing out of the outdoor heat exchanger 15 flows into the accumulator 18 through the four-way valve 14 and the gas refrigerant pipe 20, is adjusted to a predetermined refrigerant dryness by the accumulator 18, is sucked into the compressor 13, and is compressed again. The machine 13 is compressed to form a series of refrigeration cycles.

FIG. 2 shows the internal structure of a high-pressure chamber type scroll compressor as a typical example of the compressor 13 used in the refrigeration cycle system of the air conditioner described above. The scroll type compressor 13 includes a pressure vessel 103 provided with a suction pipe 101 and a discharge pipe 102. The discharge pressure chamber (high pressure chamber) 103a is formed by the pressure vessel 103. The electric motor 104 and the compression mechanism portion 105 are housed in the pressure vessel 103, and the refrigerating machine oil is stored in the lower part.

The compression mechanism 105 includes a fixed scroll 106 having a spiral gas passage and a swirl scroll 108 having a spiral wrap 107. The swivel scroll 107 is arranged so as to be movable relative to the fixed scroll 106, and the fixed scroll 106 and the swivel scroll 107 mesh with each other to form the compression chamber 109. The swivel scroll 107 is connected to an old dam ring that revolves while preventing its rotation, and is also connected to an eccentric portion 111 of a crankshaft 110 that is rotationally driven by an electric motor 104. Further, a discharge port 106a is formed in the fixed scroll 106.

By driving the electric motor 104, the crankshaft 110 is rotated, and while the swivel scroll 108 is swiveled, the refrigerant sucked from the suction pipe 101 is introduced into the compression chamber 109 and is sequentially compressed. The compressed refrigerant is discharged from the discharge port 106a of the fixed scroll 106 to the discharge pressure chamber 103a. Further, the crankshaft 110 is supported by bearings 112 and 113.

The compression mechanism of the compressor, that is, the compression chamber composed of the fixed scroll 106 and the swivel scroll 107 in the scroll compressor, has a small dimensional tolerance, and when the bearings 112 and 113 are damaged due to lack of lubricating oil, the crankshaft 110 is eccentric. However, the swivel scroll 107 and the fixed scroll 106 come into contact with each other more than in the normal design, hindering a smooth compression process such as galling, and in the worst case, the scroll becomes astringent and cannot be compressed. Therefore, sufficient lubrication with refrigerating machine oil is required.

In the compressor, the high-pressure chamber system in which the compressed refrigerant passes through the discharge pressure chamber 103a and the inside of the discharge pressure chamber 103a is filled with high-pressure gas, and the low-pressure refrigerant after the compressor is immediately discharged to the refrigeration cycle side. There is a chamber method. In particular, in the high-pressure chamber system, since the inside of the discharge pressure chamber 103a of the compressor is filled with the high-temperature and high-pressure refrigerant, the refrigerating machine oil stored in the discharge pressure chamber 103a is also exposed to the high-temperature and high-pressure refrigerant. If a large amount of water-containing air remains in the refrigeration cycle system due to inadequate evacuation, the environment is such that the oxidative deterioration reaction of the refrigerating machine oil is likely to be promoted. Therefore, in the high-pressure chamber type compressor, it is particularly important to control the residual air amount.

FIG. 3 shows the GWP values of “R1234yf” and “R1234ze (E)” as typical examples of the current refrigerants and HFO-based refrigerants used in many air conditioners. It can be seen that the current refrigerants such as "R410A", "R404A", "R125", and "R134a" have considerably large GWP values. Further, "R32" is about 1/3 of "R410A", but the GWP value is still large. On the other hand, the HFO-based refrigerants “R1234yf” and “R1234ze (E)” are GWP values that cannot be displayed on the scale of FIG. Therefore, it can be seen that the use of an HFO-based refrigerant greatly contributes to the reduction of the GWP value. Although not shown in FIG. 3, it is also possible to use "HFO1123" as the HFO-based refrigerant.

On the other hand, the HFO-based refrigerant has a high evaporation temperature and a lower refrigerant pressure than the current refrigerant "R410A" or the like. For this reason, in an air conditioner (for example, a multi-type air conditioner for buildings) in which the length of the refrigerant pipe is long and the pressure loss in the refrigerant pipe cannot be ignored, "R32" and "R32" are used for the purpose of ensuring the pressure loss and capacity of the refrigerant pipe. It is desirable to mix it with the current refrigerants such as "R125" and "R134a".

However, since the current refrigerants of "R134a" and "R125" have a high GWP value, in the present embodiment, in order to reduce the GWP value to meet the regulation value and secure the refrigerant capacity, the HFO-based refrigerant is used. At least one of "R1234yf", "R1234ze (E)", and "HFO1123" is used as a mixed refrigerant containing 20 wt% or more. As a result, the GWP value can be kept low, and a practical mixed refrigerant that can be used in an actual machine can be obtained.

Next, FIG. 4 shows the relationship between the amount of air N [mol / g] per 1 g of the refrigerating machine oil sealed in the refrigerating cycle system and the total acid value, which is one of the deterioration indexes of the refrigerating machine oil. The amount of air N [mol / g] per 1 g of refrigerating machine oil is Vpipe for the total volume in the refrigerant pipe, Vidu for the total volume of the connected indoor units, P for the degree of vacuum during construction, gas constant R, and temperature T [ Using K] and the amount of refrigerating machine oil M [g], the air is assumed to be an ideal gas and is obtained as follows.
N [mol / g] = P · (Vpipe + Vidu) / (RT · M)
FIG. 4 shows the results of PVE oil and POE oil. Each refrigerating machine oil is placed in coexistence with "R1234yf" as a representative of the HFO-based refrigerant, and is heated and accelerated and deteriorated to correspond to the product life. Compared with POE oil, it can be seen that the total acid value of PVE oil increases due to oxidative deterioration of the refrigerant and refrigerating machine oil due to air as the amount of air N [mol / g] per 1 g of refrigerating machine oil increases.

Therefore, in the coexistence of HFO-based refrigerant and PVE oil, it is desirable to reduce the amount of air N [mol / g] per 1 g of refrigerating machine oil as compared with POE oil. Here, the capacity of the acid scavenger added to the refrigerating machine oil is determined in consideration of the lubrication performance required for the refrigerating machine oil. The amount of refrigerating machine oil sealed in the air conditioner is determined from the oil rising rate of the compressor constituting the refrigerating cycle, the amount of refrigerant circulating, the length of the refrigerant piping, and the like.

In the present embodiment, in order to keep the deterioration of the refrigerating machine oil within the permissible range when PVE oil is used, the maximum upper limit of the amount of air N [mol / g] per 1 g of the refrigerating machine oil remaining in the refrigerating cycle system. However, it was found that it is desirable to set and manage it to 5.0 × ^10-5 [mol / g] or less. Of course, since POE oil has a smaller total acid value than PVE oil, there is no problem if the above relationship is established.

Next, FIG. 5 shows the relationship between the refrigerant pipe length Xp in an air conditioner using an HFO-based refrigerant and the amount of air N [mol / g] per 1 g of refrigerating machine oil. As described above, in the case of an air conditioner having a long refrigerant pipe length (for example, a multi-type air conditioner for buildings), the allowable residual air amount is set and managed according to the refrigerant pipe length. .. Then, in this embodiment, assuming that the length of the refrigerant pipe is Xp [m] and the amount of air per 1 g of refrigerating machine oil is N [mol / g], N = (4.0 × ^10-7 ) · Xp + (4.0). The allowable residual air amount is set by a linear function (indicated by a straight line A) of × ^10-6 ). This straight line A indicates the upper limit of the amount of air N [mol / g] per 1 g of refrigerating machine oil of an air conditioner using an HFO-based refrigerant in the refrigerant pipe length Xp.

The intercept (4.0 × ^10-6 ) [mol / g] of the linear function shown by the straight line A corresponds to the volume of the indoor unit. When constructing an air conditioner, the space to be evacuated is the piping connecting the outdoor unit to the indoor unit and the internal volume of the indoor unit. Therefore, even if the length of the refrigerant pipe is "0" m, the space to be evacuated is generated only by integrating the contents of the indoor unit. For example, in a multi-type air conditioner for buildings in which multiple indoor units are connected, a model with a cooling capacity of 28 kW and 6 indoor units is 2.38 x ^10-6 [mol / g], and a model with a cooling capacity of 67 kW is an indoor unit. With 9 units, it will be about 2.55 × ^10-6 [mol / g].

Therefore, the number of compressors to be installed differs depending on the capacity of the outdoor unit to be installed, and in the case of a large-capacity model, multiple small-capacity outdoor units are connected to achieve that capacity, and the compressor is frozen by the outdoor unit of the configuration system. Since the amount of machine oil held is different, a section of about (4.0 × ^10-6 ) [mol / g] is required.

If the upper limit is exceeded, the vacuum drying in the refrigerating cycle system of the air conditioner is insufficient, and there is a possibility that a predetermined amount or more of oxygen and water remain in the refrigerating cycle system. It is expensive and may cause a malfunction of the compressor. Therefore, if the allowable residual air amount is set and managed below the upper limit shown in the straight line A according to the refrigerant pipe length Xp, oxygen and moisture exceeding the allowable amount will not remain in the refrigeration cycle system, so that the compressor may fail. It will be possible to suppress it.

Therefore, in addition to the condition of 5.0 × ^10-5 [mol / g] or less, which is the maximum upper limit value of the refrigeration cycle system described above, and the condition of the lower limit value described below, per 1 g of refrigerating machine oil in the region Am. By setting and managing the amount of air N [mol / g], it is possible to provide an air conditioner using an HFO-based refrigerant and PVE oil whose reliability is ensured for a long period of time. ..

Here, the lower limit of the amount of air N [mol / g] per 1 g of refrigerating machine oil is determined as follows. If the amount of residual air in the refrigeration cycle system is reduced as much as possible, the oxidative deterioration of the refrigerating machine oil can be further suppressed, but for this purpose, it is necessary to take a sufficient amount of time to evacuate, and in particular, It is unrealistic in the construction period of installation and relocation work of an air conditioner with a limited schedule such as a multi-air conditioner for buildings. Therefore, in the present embodiment, the amount of air N [mol / g] remaining in the refrigeration cycle system per 1 g of refrigerating machine oil is a linear function of N = (5.0 × 10 ⁻⁹ ) · Xp (indicated by a straight line B). ) Is set as the lower limit.

As described above, the straight line B indicates the lower limit of the amount of air N [mol / g] per 1 g of refrigerating machine oil in the air conditioner using the HFO-based refrigerant at the refrigerant pipe length Xp, and actually freezes. The allowable residual air amount N [mol / g] per 1 g of machine oil is 5.0 × 10 ^-5 [mol / g] or less, which is the maximum, and (5.0 × 10 ^-9 ) · Xp ≦ N ≦ (4. It is set and managed in the area Am determined by 0 × ^10-7 ) and Xp + (4.0 × ^10-6 ).

The refrigerating machine oil used in the present embodiment has a relatively high viscosity and pressure coefficient of POE from the viewpoint of forming an oil film under Hertz pressure on the sliding surface where the fixed scroll 106 and the swivel scroll 107 inside the bearing or compressor come into contact with each other. It is desirable to use oil or PVE oil, but among them, PVE oil has a high viscosity-pressure coefficient and good formation of an oil film, and is therefore advantageous in forming an oil film on a sliding surface. Therefore, in the present embodiment, the HFO-based refrigerant and PVE oil are used, and the allowable residual air amount N [mol / g] of the refrigeration cycle system per 1 g of refrigerating machine oil is set and managed in the above-mentioned region Am.

In the conventional compressor, a sliding bearing has been used for the bearing 113, but in the present embodiment, it is desirable to use a rolling bearing for the bearing 113. The rolling bearing uses a spherical or cylindrical roller as the rolling element. The plain bearing is in surface contact with the rotating shaft, whereas the rolling bearing uses a rolling element, so that it is in point contact or line contact.

For this reason, the frictional resistance is small against rotational movement, which leads to a reduction in the electrical input of the compressor, but from the viewpoint of lubrication, the conditions are harsh, and it is important to form an oil film with the refrigerating machine oil inside the compressor and secure an oil film. Become. Therefore, by using PVE oil or POE oil, which has a high viscosity-pressure coefficient and easily forms an oil film, it is possible to secure an oil film on the bearing, avoid bearing damage, and further improve the reliability of the air conditioner. it can.

Further, the refrigerating machine oil of the present embodiment, it is desirable that the viscosity of the refrigerating machine oil only when the oil temperature is 40 ° C. is 40mm ² / s~100mm ² / s. Refrigerating machine oil is dissolved in a liquid refrigerant and mixed with a gaseous refrigerant or a liquid refrigerant and circulated in the refrigeration cycle system. Especially when the actual viscosity in the state of being dissolved in the refrigerant decreases, the above-mentioned sliding It becomes difficult to form an oil film in the part.

Further, when the viscosity is lowered more than necessary, the airtightness of the compression chamber composed of the fixed scroll 106 and the swivel scroll 107 cannot be maintained, the refrigerant leaks in the compression process, and the problem of a decrease in compressor efficiency occurs. Further, when the viscosity of the oil alone is set high, the mechanical loss such as viscous resistance and frictional resistance increases, and in this case also, the compressor efficiency is lowered. Therefore, the viscosity of the refrigerating machine oil only when the oil temperature is 40 ° C. is using the refrigeration oil of 40mm ² / s~100mm ² / s.

Further, in the air conditioner of the present embodiment, the allowable residual air amount of the refrigeration cycle system is controlled, and the oxidative deterioration of the refrigerant and the refrigerating machine oil is kept within the permissible value within the product life of the air conditioner to ensure reliability. It is something to do. However, in the case of a commercial air conditioner that connects multiple indoor units, has a long refrigerant pipe length, and has a large refrigerating capacity, there is a high possibility that the equipment will be replaced or relocated even after the air conditioner is installed. .. In addition, it is desirable to add a stabilizer in order to cope with the increase in total acid value and oxidative deterioration due to the aged deterioration of the refrigerating machine oil and the refrigerant itself, and to ensure the lubricity of the refrigerating machine oil.

Examples of stabilizers are antioxidants that prevent oxidative deterioration of refrigerating machine oil, acid scavengers that capture acids that are generated as deteriorated substances when refrigerating machine oil and refrigerant deteriorate, and poles that ensure the lubricity of refrigerating machine oil. Examples include pressure agents. DBPC (2,6-di-t-butyl-p-cresol) is a typical example of an antioxidant in which at least two or more of these antioxidants, acid scavengers, and extreme pressure agents are desirable to be added. It is desirable to prevent oxidative deterioration of refrigerating machine oil by adding a phenolic antioxidant to ensure long-term reliability. Further, as the acid scavenger, by adopting glycidyl ether or glycidyl ester having an epoxy group or other carbodiimide-based compounds, these react with acids and water in the refrigerating machine oil and become harmless substances in the refrigerating cycle.

In particular, the acid scavenger may cause a decrease in the viscosity of the base refrigerating machine oil when the addition amount is excessive depending on the compound to be added. The effect of the decrease in viscosity is as described above. If the amount added is small, the acid scavenging ability itself is lost. Therefore, it is desirable to add an acid scavenger of about 0.1 wt% to 2.0 wt% from the balance between the two.

The present invention is not limited to the above-mentioned examples, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

10 ... outdoor unit, 11 ... gas connection piping, 12 ... liquid connection piping, 13 ... compressor, 14 ... four-way valve, 15 ... outdoor heat exchanger, 16 ... outdoor blower, 17 ... outdoor expansion valve, 18 ... accumulator, 19 ... Compressor suction piping, 20 ... Gas refrigerant piping, 30 ... Indoor unit, 31 ... Indoor heat exchanger, 32 ... Indoor blower, 33 ... Indoor expansion valve.

Claims (7)

At least a plurality of indoor units including an indoor expansion valve, an indoor heat exchanger, and an indoor blower, and at least a compressor connected to the plurality of indoor units by liquid connection pipes and gas connection pipes, and outdoor expansion. In the management method of an air conditioner composed of an outdoor unit including a valve, an outdoor heat exchanger, and an outdoor blower.
The refrigeration cycle system including the indoor unit and the refrigerant pipes constituting the outdoor unit is a refrigeration cycle system in which a refrigerant containing 20 wt% or more of a hydrofluoroolefin (hereinafter referred to as HFO) refrigerant and refrigerating machine oil are sealed. The amount of air N [mol / g] remaining in the refrigeration cycle system with respect to 1 g of the refrigerating machine oil is N = (4.0 × ^10-7 ) · Xp + when the pipe length of the refrigerant pipe is Xp [m]. A method for managing an air conditioner, which is controlled to a value that does not exceed the amount of air N [mol / g] determined by (4.0 × ^10-6 ). In the method for managing an air conditioner according to claim 1,
The maximum amount of air N [mol / g] remaining in the refrigeration cycle system per 1 g of the refrigerating machine oil is controlled to a value of 5.0 × 10 ⁻⁵ [mol / g] or less. How to manage an air conditioner. In the method for managing an air conditioner according to claim 2,
The amount of air N [mol / g] remaining in the refrigeration cycle system per 1 g of the refrigerating machine oil is N = (5.0 × 10 ^-9 ) when the pipe length of the refrigerant pipe is Xp [m]. A method for managing an air conditioner, which is controlled to a value larger than the amount of air N [mol / g] determined by Xp. In the method for managing an air conditioner according to any one of claims 1 to 3,
A method for managing an air conditioner, characterized in that at least one of "R1234yf", "R1234ze (E)", and "HFO1123" is sealed as the HFO-based refrigerant. In the method for managing an air conditioner according to any one of claims 1 to 4.
A method for managing an air conditioner, wherein the refrigerating machine oil is polyvinyl ether oil. In the management method of the air conditioner according to claim 5,
A method for managing an air conditioner, characterized in that at least two or more of an antioxidant, an acid scavenger, and an extreme pressure agent are added to the refrigerating machine oil. In the management method of the air conditioner according to claim 6,
A method for managing an air conditioner, wherein a rolling bearing is used for a bearing that supports a rotating shaft of a compression mechanism of the compressor.

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