JP2012087959A - Refrigeration apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration apparatus that prevents a deterioration product of a refrigerant from promoting wears of sliding parts even when using hydrofluoroolefin as the refrigerant and can stably operate.SOLUTION: The refrigeration apparatus is enclosed with a single refrigerant composed of hydrofluoroolefin having a double bond between carbons or refrigerant having the hydrofluoroolefin as a basic component and prepared by being mixed with hydrofluorocarbon not having a double bond and includes a refrigerant circulation route in which the refrigerant circulates through a compressor 1, a condenser 2, an expansion mechanism 3 and an evaporator 4, wherein a refrigerant oil of the compressor contains a sulfur-based extreme-pressure additive agent. In the refrigeration apparatus, the sulfur-based extreme-pressure additive agent reacts with a sliding surface to form a sulfur-containing extreme-pressure layer before a hydrogen fluoride generated by an oxidation reaction of the refrigerant and other reaction products attack the sliding surface of the compressor, thereby preventing a stick and slip caused between sliding surfaces and reducing a frictional wear. Accordingly, the refrigeration apparatus secures reliability of the sliding surfaces.

Description

  The present invention relates to a refrigeration apparatus including a compressor, a condenser, an expansion mechanism, and an evaporator, in which a hydrofluoroolefin having no chlorine atom and having a double bond between carbon and carbon is used as a refrigerant, and refrigeration oil is enclosed. .

  Conventionally, for example, in a refrigeration cycle formed in an air conditioner or a car air conditioner, a fluorinated hydrocarbon (HFC) containing fluorine and hydrogen has been used as a refrigerant. Further, in such a refrigeration apparatus, from the viewpoint of compatibility with HFC as a refrigerant, a refrigerating machine oil having a polarity such as polyalkylene glycol (PAG), polyol ester (POE) or polyvinyl ether (PVE) is used. Has been used.

  Conventionally, in such a refrigeration cycle, it is known that sludge is generated due to wear powder or a degradation product of refrigeration oil in the system when severe wear occurs in the sliding portion of the compressor. In order to prevent such intense wear, the sliding part is hardened on the compressor side, and on the refrigerator oil side, it is possible to add additives such as extreme pressure additives, phosphorus-based antiwear agents and oiliness agents. I have done it. Moreover, deterioration was prevented by managing the moisture and air mixed in the refrigeration cycle.

  In recent years, hydrofluoroolefin, which is a new refrigerant having a small global warming potential, has been studied as a refrigerant in place of HFC in order to prevent global warming (for example, Patent Document 1).

JP 2009-2222033 A

  The hydrofluoroolefin refrigerant disclosed in the patent document has a double bond in the molecule, and has a relatively unstable molecular structure with respect to moisture, oxygen and the like as compared with a conventional HFC. For this reason, the deteriorated product of the refrigerant reacts particularly at a portion where the temperature is high, such as a sliding portion of the compressor, and wear of the sliding portion is promoted, which may impair the reliability of the refrigeration apparatus.

  Therefore, the object of the present invention is to prevent the deterioration product of the refrigerant, which is a reaction of the hydrofluoroolefin, which is the refrigerant, with moisture, oxygen, etc. An object of the present invention is to provide a refrigeration apparatus that can suppress deterioration and operate stably over a long period of time.

  In order to achieve the above object, the present invention provides a single refrigerant of a hydrofluoroolefin having a double bond between carbons or a refrigerant mixed with a hydrofluorocarbon having such a base component and having no double bond. The refrigerant is provided with a refrigerant circulation path through which the refrigerant circulates through a compressor, a condenser, an expansion mechanism, and an evaporator, and contains a sulfur-based extreme pressure additive in the refrigerating machine oil of the compressor.

According to the above configuration, since the sulfur-based extreme pressure additive is contained in the refrigerating machine oil in the refrigeration apparatus,
Before the hydrogen fluoride and other reaction products generated by the oxidation reaction of the hydrofluoroolefin-based refrigerant attack the sliding surface of the compressor, the sulfur-based extreme pressure additive reacts with the sliding surface to cause a sulfur-containing electrode. A pressure layer is formed. This sulfur-containing extreme pressure layer has a coating with a C—S bond that is easy to shear and prevents stick-and-slip between sliding surfaces to reduce frictional wear. The extreme pressure effect can be exhibited even in a situation where there is little oil, and the reliability of the sliding surface can be secured.

Cycle diagram of the refrigeration apparatus in Embodiment 1 of the present invention Characteristic chart showing the global warming potential depending on the mixing ratio of refrigerant mixed with two components

  According to a first aspect of the present invention, a single refrigerant of hydrofluoroolefin having a double bond between carbons or a refrigerant mixed with a hydrofluorocarbon having the base component and not having a double bond is sealed. A refrigerant circulation path that circulates through a compressor, a condenser, an expansion mechanism, and an evaporator is provided, and a sulfur-based extreme pressure additive is contained in the refrigerating machine oil of the compressor.

  Thus, before the hydrogen fluoride and other reaction products generated by the oxidation reaction of the hydrofluoroolefin refrigerant attack the sliding surface of the compressor, the sulfur-based extreme pressure additive reacts with the sliding surface, A sulfur-containing extreme pressure layer is formed. This sulfur-containing extreme pressure layer has a coating with a C—S bond that is easy to shear and prevents stick-and-slip between sliding surfaces to reduce frictional wear. The extreme pressure effect can be exhibited even in a situation where there is little oil, and the reliability of the sliding surface can be secured.

  The second invention uses the sulfur-based extreme pressure additive in which the number of sulfur bridges of the sulfur-based extreme pressure additive is 3 or less and the number of sulfur bridges is 3 or less in the refrigerating machine oil according to the first invention. Therefore, even if the sliding surface becomes high temperature, sulfur atoms are not easily liberated, and reaction with copper in the refrigeration apparatus due to sulfur atoms can be prevented, so that the reliability in the refrigeration apparatus can be ensured.

  The third invention includes a metal deactivator in the refrigerating machine oil according to the first or second invention, and adheres to the surface of copper used for piping or the like in the refrigeration apparatus. Reaction with the pressure additive can be prevented.

  In a fourth aspect of the invention, the refrigerating machine oil according to any one of the first to third aspects of the invention contains both a sulfur type extreme pressure additive and a phosphorus type extreme pressure additive. When the system extreme pressure additive is a high load, the sulfur system extreme pressure additive effectively acts on the sliding surface, so that the sliding characteristics in a wide load range of the compressor can be improved.

  In a fifth aspect of the present invention, the refrigerating machine oil according to the first to fourth aspects of the present invention comprises at least one of a polyol ester, polyvinyl ether, and polyalkylene glycol as a main component. These polyol ester, polyvinyl ether, and polyalkylene glycol are: Since the compatibility with the refrigerant is good, the refrigeration oil can be circulated together with the refrigerant in the refrigeration apparatus, and the refrigeration oil discharged from the compressor can be returned. Therefore, it is possible to prevent poor lubrication due to a shortage of refrigerating machine oil in the compressor.

  In a sixth aspect of the invention, in the first to fifth aspects of the invention, the sliding member constituting the sliding portion of the compressor has a surface modification layer, and the sliding member constituting the sliding portion of the compressor is surfaced. Since the modified layer is provided, the polarity of the surface of the sliding portion can be maintained, and since the uniform extreme pressure layer is formed on the sliding surface, the reliability of the sliding surface can be ensured.

  According to a seventh invention, in the first to sixth inventions, the hydrofluoroolefin has tetrafluoropropene as a base component, difluoromethane and pentafluoroethane as hydrofluorocarbons, and a global warming coefficient of 5 or more and 750 or less. In addition, it is preferable to enclose a refrigerant mixed with two or three components so as to be 300 or less, and even if unrecovered refrigerant is released to the atmosphere, the influence on global warming can be kept to a minimum. .

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

(Embodiment 1)
FIG. 1 is a cycle diagram of a refrigeration apparatus in Embodiment 1 of the present invention. In FIG. 1, the refrigeration apparatus includes, as a refrigerant circulation path, a compressor 1 that compresses refrigerant, an outdoor heat exchanger 2 that condenses or evaporates the refrigerant, an expansion mechanism 3 that expands the refrigerant such as an expansion valve, and the like. And an indoor heat exchanger 4 for evaporating or condensing the refrigerant. The refrigeration apparatus further includes a pipe 5, a four-way valve 6, and an accumulator 7 that connect the above-described configurations, and uses refrigerant and refrigerating machine oil as working media. Refrigerating machine oil is usually enclosed in a compressor, and a small part of it circulates in the refrigeration cycle together with the refrigerant during use.

  2,3,3,3-tetrafluoro-1-propene (hereinafter referred to as “HFO-1234yf”) is used as the refrigerant in the present embodiment.

  Furthermore, in FIG. 1, the refrigerating machine oil enclosed in the compressor 1 includes a base oil having compatibility with the refrigerant. In this embodiment, it is possible to use a refrigerating machine oil whose main component is at least one base oil of polyol ester, polyvinyl ether, or polyalkylene glycol.

  Of the three types of refrigerating machine oil according to the present embodiment, refrigerating machine oil mainly composed of polyol ester is used. Here, the polyol ester refrigerating machine oil is synthesized by a dehydration reaction between a polyhydric alcohol and a saturated or unsaturated fatty acid. As the polyhydric alcohol, neopentyl glycol, pentaerythritol, dipentaerythritol and the like are used according to the viscosity of the refrigerating machine oil. One saturated fatty acid includes straight-chain fatty acids such as hexanoic acid, heptanoic acid, nonanoic acid, and decanoic acid, and branched such as 2-methylhexanoic acid, 2-ethylhexanoic acid, and 3,5,5-trimethylhexanoic acid. Chain fatty acids are used. Note that polyol ester oils containing linear fatty acids have good sliding properties but poor hydrolyzability, and ester oils containing branched chain fatty acids have the advantage of being difficult to hydrolyze, although they have slightly poor sliding properties. Should.

  Further, the refrigerating machine oil of the present embodiment includes various sulfur-based extreme pressure additives and, if necessary, an antioxidant such as dibutyl-p-cresol, an acid scavenger such as an epoxy-containing compound, and an antifoaming agent. Additives are selectively added.

  Examples of sulfur-based extreme pressure additives include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized olefins, dialkyl polysulfides, dibenzyl disulfides, oligomer polysulfides, and the like. These sulfur-based extreme pressure additives preferably have 3 or less sulfur bridges. If the sulfur cross-linking length is 4 or more, sulfur is likely to be released into the refrigerating machine oil, which may corrode copper used in piping or the like in the refrigeration cycle.

  It is also preferable to use a metal deactivator for the purpose of preventing sulfur copper pipe corrosion. In the present embodiment, benzotriazoles are used as a metal deactivator.

  Furthermore, it is preferable to use a phosphorus-based extreme pressure additive at the same time to improve the extreme pressure effect. Phosphorus extreme pressure additives include phosphate esters such as tricresyl phosphate and triphenyl phosphate, phosphite esters, amine salts of acidic phosphate esters, etc., but excellent compatibility with refrigerating machine oil Acid phosphates such as tricresyl phosphate and triphenyl phosphate are optimal. Phosphorus extreme pressure additives are effective at lower loads than sulfur extreme pressure additives, so using sulfur extreme pressure additives and phosphorus extreme pressure additives in a wide frequency range with inverter control Ideal for use in compressors of refrigeration cycles.

  The compressor used in the present embodiment is a general rotary compressor, in which a piston rotates eccentrically in a cylinder and sucks, compresses, and discharges refrigerant while pushing a vane tip. Therefore, a surface modification layer is formed at the tip of the vane that becomes the sliding portion. The surface modification layer at the tip of the vane has a polarity maintaining effect, and is formed by dispersing, for example, graphite having connected benzene rings. When refrigerating machine oil approaches, it is induced by its polarity and polarization occurs in the surface modification layer, indicating polarity. As a result, the extreme pressure additive in the refrigerating machine oil is adsorbed to further form an extreme pressure layer. When the extreme pressure layer formed causes severe sliding conditions, for example, when left for half a day at a low outside temperature of −10 ° C. or less and then starts up with heating and starts operating at maximum capacity, the sliding part has insufficient lubricating oil. However, since the extreme pressure layer is sufficiently formed in the sliding portion as in the present embodiment, abnormal wear of the sliding portion does not occur.

  In a refrigeration cycle containing a sulfur-based extreme pressure additive in refrigeration oil as shown in FIG. 1, during cooling operation, high-temperature and high-pressure refrigerant gas discharged from the compressor 1 is transferred to the four-way valve 6 and the outdoor heat exchanger 2. Condensed and liquefied. The liquefied refrigerant is reduced in pressure through the expansion mechanism 3 and enters the indoor heat exchanger 4. Further, the low-temperature and low-pressure liquid refrigerant evaporates and exchanges heat with room air, becomes a low-temperature and low-pressure gas refrigerant, passes through the accumulator 7 and returns to the compressor 1.

  Further, since the flow path is reversed by the four-way valve 6 during the heating operation, the refrigerant that has exited the compressor 1 passes through the four-way valve 6 and exchanges heat with indoor air in the indoor heat exchanger 4 to be condensed and liquefied. The liquefied refrigerant is decompressed through the expansion mechanism 3, evaporated in the outdoor heat exchanger 2, becomes a low-temperature and low-pressure gas, returns to the compressor 1 through the accumulator 7.

  In the refrigeration apparatus, the motor portion and the discharge portion in the compressor 1 are the highest temperature portions, and the sliding portion is further heated. In such a high temperature part, the extreme pressure additive contained in the refrigerating machine oil decomposes and reacts with the surface to form an extreme pressure layer.

  In the above embodiment, the refrigerant sealed in the refrigeration apparatus is a hydrofluoroolefin, for example, tetrafluoropropene (HFO1234yf) as a basic component, either difluoromethane (HFC32) or pentafluoroethane (HFC125). Or it is the refrigerant | coolant which mixed 2 components or 3 components, respectively, so that a global warming potential (GWP) might be 5 or more and 750 or less, desirably 5 or more and 300 or less. Alternatively, a single refrigerant (GWP = 4) of hydrofluoroolefin may be used.

  FIG. 2 is a characteristic diagram showing a global warming potential according to a mixing ratio of a refrigerant in which two components of tetrafluoropropene and difluoromethane or pentafluoroethane are mixed. Specifically, as shown in FIG. 2, in the case of mixing two components, in order to mix tetrafluoropropene and difluoromethane to make GWP300 or less, the content of difluoromethane is 44 wt% or less, tetrafluoropropene and pentafluoroethane. In order to make GWP750 or less by mixing the above, pentafluoroethane is 21.3 wt% or less, and in order to make GWP300 or less, pentafluoroethane is mixed with 8.4 wt% or less.

  Also, when the refrigerant is a single refrigerant of tetrafluoropropene, it becomes GWP4 and shows a very good value. However, since the refrigerating capacity is reduced due to the large specific volume as compared with the refrigerant mixed with hydrofluorocarbon, a larger cooling cycle device is required. In other words, if a refrigerant in which a hydrofluoroolefin having a double bond between carbon and carbon is used as a basic component and a hydrofluorocarbon having no double bond is used, the refrigerant is refrigerated as compared with a single refrigerant of hydrofluoroolefin. It is possible to improve the predetermined characteristics such as capacity and make it easier to use as a refrigerant. Therefore, in the refrigerant to be sealed, the ratio of tetrafluoropropene including a single refrigerant is appropriately selected according to the purpose of the cooling cycle apparatus incorporating the compressor and the above-mentioned conditions such as the GWP restriction. That's fine.

  Even if the refrigerant | coolant which is not collect | recovered by this is discharge | released to air | atmosphere, the influence can be kept to the minimum with respect to global warming. In addition, the mixed refrigerant mixed at the above ratio can reduce the temperature difference in spite of the non-azeotropic mixed refrigerant and behaves more like a pseudo-azeotropic mixed refrigerant, improving the cooling performance and cooling performance coefficient (COP) of the refrigeration system. can do.

  In this embodiment, the refrigeration apparatus mainly composed of an air conditioner for air conditioning is described. However, the effect is the same as long as the refrigeration apparatus is not an open type, and a refrigerator, a freezer, a dehumidifier, and a heat pump type dryer are used. Needless to say, this technology can be applied to washing machines, heat pump water heaters, beverage vending machines, and the like.

  The refrigerating apparatus according to the present invention includes a sulfur-based extreme pressure additive in the refrigerating machine oil to form an extreme pressure layer that easily shears on the sliding surface of the compressor, and the oil on the sliding surface such as when the refrigerating apparatus is started up. The extreme pressure effect can be exhibited even in a small amount of conditions, and the reliability of the sliding surface of the compressor can be secured, so the air conditioner, car air conditioner, hot water heater, freezer refrigerator, freezer, dehumidifier, heat pump type It can be applied to applications such as dry washing machines, heat pump water heaters, and beverage vending machines.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Outdoor heat exchanger 3 Expansion mechanism 4 Indoor heat exchanger 5 Piping 6 Four-way valve 7 Accumulator

Claims (7)

A single refrigerant of hydrofluoroolefin having a double bond between carbon or carbon, or a refrigerant mixed with hydrofluorocarbon not having a double bond, which is a base component thereof, is enclosed in a compressor, a condenser, A refrigerating apparatus comprising a refrigerant circulation path for circulating an expansion mechanism and an evaporator, and containing a sulfur-based extreme pressure additive in the refrigerating machine oil of the compressor. The refrigeration apparatus according to claim 1, wherein the sulfur-based extreme pressure additive has 3 or less sulfur bridges. The refrigerating apparatus according to claim 1 or 2, wherein the refrigerating machine oil contains a metal deactivator. The refrigerating apparatus according to any one of claims 1 to 3, wherein the refrigerating machine oil contains both a phosphorus-based extreme pressure additive in addition to the sulfur-based extreme pressure additive. The refrigerating apparatus according to any one of claims 1 to 4, wherein the refrigerating machine oil contains at least one of polyol ester, polyvinyl ether, and polyalkylene glycol as a main component. The refrigeration apparatus according to any one of claims 1 to 5, wherein the sliding member constituting the sliding portion of the compressor has a surface modification layer. Hydrofluoroolefin is composed of tetrafluoropropene as the base component, and difluoromethane and pentafluoroethane as hydrofluorocarbons are mixed in two components so that the global warming potential is 5 or more and 750 or less, preferably 300 or less. Or the refrigeration apparatus of any one of Claims 1-6 which enclosed the refrigerant | coolant which mixed 3 components.