US20120024007A1

US20120024007A1 - Compressor for refrigeration and air-conditioning and refrigerating and air-conditioning apparatus

Info

Publication number: US20120024007A1
Application number: US13/193,655
Authority: US
Inventors: Ryo Ota; Tsuneji Sugano; Kuninari Araki
Original assignee: Hitachi Appliances Inc
Current assignee: Hitachi Appliances Inc
Priority date: 2010-07-29
Filing date: 2011-07-29
Publication date: 2012-02-02
Also published as: KR20120023537A; KR101280701B1; CN102408936A; JP2012031239A

Abstract

A refrigerating machine oil including a refrigerating machine oil basis such as polyol ester oil and an additive polyol ester oil is mixed to a refrigerant including 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene or the like. A compressor for refrigeration and air-conditioning including the mixture charged therein is used. The composition of the additive polyol ester oil is 1 to 30 wt %.

The wear resistance of the compressor is improved, and the efficiency of a refrigerating and air-conditioning apparatus using the compressor is enhanced.

Description

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent application serial No. 2010-169889, filed on Jul. 29, 2010, the content of which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a compressor for refrigeration and air-conditioning and a refrigerating and air-conditioning apparatus using a heat pump cycle.
2. Description of Related Art
As the global environment measures in a refrigerating and air-conditioning system field, mention may be made of substitution of CFC (Chlorofluorocarbons) and HCFC (Hydrochlorofluorocarbons) used as refrigerants or heat insulating materials as ozone depleting substances, and substitution of HFC (Hydrofluorocarbons) used for enhancement of efficiency or refrigerants as global warming countermeasures. These have been positively pursued.
For substitutes of CFC and HCFC which are ozone depleting substances, selection of refrigerants and heat insulating materials, and development of equipment have been pursued with the aims of preventing the depletion of the ozone layer, providing low toxicity and flammability, and being capable of ensuring efficiency. As a result, for the heat insulating materials for refrigerators, substitution of the blowing agent from CFC11 to HCFC141b and cyclopentane has been done in this order. Currently, there has been made a shift to use in combination with a vacuum heat insulating material.
The refrigerant was sequentially changed from CFC12C to HFC134a (GWP (Global Warming Potential)=1430) in a refrigerator or a car air conditioner, and was changed from HCFC22 to R410A (HFC32/HFC125 (50/50 wt %) mixture: GWP=2088) in a room air conditioner or a package air conditioner.
However, in the third session of the Conference of Parties to the United Nations Framework Convention on Climate Change (COP3) held in Kyoto in 1997), the HFC emission was to be converted to the CO₂equivalent emission as a greenhouse gas, to be subject to the regulation. Accordingly, reduction of HFC has come to be pursued.
Thus, in home refrigerators, the amount of a refrigerant charged therein is small, and flammable refrigerants are also judged as usable from the viewpoint of manufacturing. Accordingly, HFC134a was substituted with flammable R600a (isobutane: GWP=3). Further, attention has currently also been directed to HFC134a for the car air conditioners, and R410A for room air conditioners and package air conditioners due to a groundswell of popular opinion. Whereas, in industrial refrigerators, the amount of R600a charged is large. Thus, HFC134a is used even at present because of a concern about the flammability.
In actuality, by the Home Appliance Recycling Law (Law for Recycling of Specified kinds of Home Appliances) enforced in 2001, and the End-of-life Vehicle Recycling Law (Act on Recycling, etc. of End-of-life Vehicles) enforced in 2003, recycling of equipment is obliged. Thus, HFC and the like used as refrigerants are recovered and treated. However, in EU (the European Union), in the 2006 Directive (the Directive 2006/40/EC), use of refrigerants with a GWP of more than 150 as the refrigerants for use in car air conditioners was prohibited from those shipped in January, 2011. In response to this, the car air conditioner industry shows various movements. Concerns are rising that R410A will be also regulated sometime for room air conditioners. There may be review of regulations including those on fixed air conditioners in 2011 based on the EU Directive. This accelerates the study on alternative refrigerants.
For the alternative refrigerants, 2,3,3,3-tetrafluoropropene (HFO1234yf (Hydrofluoroolefine)) (GWP=4) and 1,3,3,3-tetrafluoropropene (HFO1234ze) (GWP=10) become candidates alone or in mixture thereof because they have the same thermal physical properties as that of HFC134a, and each have a low GWP, a low toxicity, a low flammability and the like. The refrigerant to be mixed with 2,3,3,3-tetrafluoropropene is mainly difluoromethane (HFC32).
Further, it can be also considered that HFC134a or HFC125 is mixed according to GWP allowable for low flammability. As other refrigerants, mention may be made of hydrocarbons such as propane and propylene, and low GWP hydrofluorocarbons such as fluoroethane (HFC161), difluoroethane (HFC152a), and difluoromethane (HFC32).
On the other hand, a refrigerating machine oil is used for a closed electric compressor, and plays roles of lubrication, sealing, cooling and the like of the sliding part.
For air conditioners, APF (Annual Performance Factor) is adopted as an index indicating the energy saving performance in accordance with the actual usage by the Energy Saving Law (Law concerning the Rational Use of Energy) revised from 2006. Also for compressors, further saving in energy and higher efficiency are required. Thus, the use conditions become severe. This results in a demand for a refrigerating machine oil with good lubricity in view of ensuring the reliability.
As refrigerating machine oils for use in compressors using each single refrigerant of 2,3,3,3-tetrafluoropropene (HFO1234yf) and 1,3,3,3-tetrafluoropropene (HFO1234ze), or a mixed refrigerant including the refrigerants, there are disclosed polyalkylene glycol oils, mineral oils, poly-alpha-olefin oils, and alkylbenzene oils from the foregoing circumstances (e.g., Japanese Translation of PCT Application No. 2009-540170 (Patent Document 1)).
JP-A No. S58-93796 (Patent Document 2) discloses a refrigerating machine oil composition in which a fraction with a boiling point of 50 to 250° C. under ordinary pressure, and a viscosity of 5 centistokes/40° C. or less is contained in a refrigerating machine oil including at least one of paraffin type refrigerating machine oils, naphthene type refrigerating machine oils and synthetic refrigerating machine oils.
Other than these, Japanese Translation of PCT Application No. 2007-532767 (Patent Document 3), Japanese Translation of PCT Application No. 2007-538115 (Patent Document 4), Japanese Translation of PCT Application No. 2008-504374 (Patent Document 5), Japanese Translation of PCT Application No. 2008-505989 (Patent Document 6), Japanese Translation of PCT Application No. 2008-506793 (Patent Document 7), Japanese Translation of PCT Application No. 2008-524433 (Patent Document 8) and Japanese Translation of PCT Application No. 2008-239814 (Patent Document 9) disclose azeotrope-like compositions including HFO-1234yf, HFO-1225yeZ, trans-1,3,3,3-pentafluoropropane (transHFO-1234ze), 1,1-difluoroethane (HFC-152a), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,2,2-pentafluoroethane (HFC-125) and the like, and lubricants such as mineral oils (including paraffin oils or naphthene oils), silicone oil, polyalkylbenzene, polyol ester, polyalkylene glycol, polyalkylene glycol ester, polyvinyl ether, poly(alpha-olefin) and halocarbon oil.

SUMMARY OF THE INVENTION

2,3,3,3-Tetrafluoropropene (HFO1234yf) and 1,3,3,3-tetrafluoropropene (HFO1234ze) are lower-pressure refrigerants than R410A. Accordingly, it is essential to increase the volume of displacement of the compressor and increase the rotation speed thereof for gaining the circulating refrigerant amount. For this reason, in the case of the refrigerating machine oils, there remains a problem on the wear resistance in sliding parts such as compressor bearings.
Further, refrigerants such as HFO1234yf, HFO1234ze, propane, propylene and fluoroethane each have a very high miscibility with the refrigerating machine oils, and the amount of each refrigerant dissolved in the compressor is large. This results in reduction of the refrigerant dissolved viscosity in the refrigerating machine oil. This unfavorably causes reduction of the sealing property of the compression part, and further an increase in wear amount of the sliding part.
For the foregoing reasons, a refrigerating machine oil capable of ensuring both the improvement of efficiency and the wear resistance of the system is preferably used for a refrigerating and air-conditioning apparatus.
It is an object of the present invention to improve the wear resistance of a compressor for refrigeration and air-conditioning using refrigerants for refrigeration and air-conditioning such as refrigerants including 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene and the like, or hydrocarbons such as propane and propylene, fluoroethane (HFC161), difluoroethane (HFC152a), difluoromethane (HFC32) and R410A as refrigerants, and to implement a higher efficiency of the refrigerating and air-conditioning system using the compressor.
The compressor for refrigeration and air-conditioning of the present invention includes a mixture charged therein. The mixture includes a refrigerant including 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene or the like; and a refrigerating machine oil including a refrigerating machine oil basis such as polyol ester oil, and an additive polyol ester oil. The compressor is characterized in that the composition of the additive polyol ester oil is 1 to 30 wt %.
In accordance with the present invention, it is possible to obtain a compressor which has achieved both the improvement of the performances of the compressor and the wear resistance thereof without using a phosphorus-containing extreme pressure agent detrimental to environment as the additive of the refrigerating machine oil.
Further, in accordance with the present invention, it is possible to obtain an environmentally friendly refrigerating and air-conditioning apparatus capable of achieving both the improvement of performances and the long-term reliability of the refrigerating and air-conditioning apparatus without using the phosphorus-containing extreme pressure agent as the additive of the refrigerating machine oil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram showing a room air conditioner.

FIG. 2 is a cross-sectional view showing a scroll type closed compressor for a room air conditioner.

DETAILED DESCRIPTION OF THE INVENTION

Below, a description will be given to a compressor for refrigeration and air-conditioning in accordance with an embodiment of the present invention, and a refrigerating and air-conditioning apparatus using the same.
The compressor for refrigeration and air-conditioning includes a mixture therein. The mixture includes a charged refrigerant which is a refrigerant including 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene or difluoromethane, or R410A; and a refrigerating machine oil including a refrigerating machine oil basis including at least one base oil selected from the group consisting of polyol ester oils expressed by the following chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), and an additive polyol ester oil expressed by the following chemical formula (3) (where in the formula, R₂represents an alkyl group having 7 to 9 carbon atoms).
The compressor for refrigeration and air-conditioning is charged with a mixture of a charged refrigerant which is a refrigerant including 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, propane, propylene or fluoroethane; and a refrigerating machine oil basis including at least one base oil selected from the group consisting of mineral oils, polyvinyl ether oils, or polyol ester oils expressed by the chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), the refrigerating machine oil basis having a lower critical solution temperature of −30° C. or less; and an additive polyol ester oil expressed by the chemical formula (3) (where in the formula, R₂represents an alkyl group having 7 to 9 carbon atoms). Then, the composition of the additive polyol ester oil is 1 to 30 wt %.
In the compressor for refrigeration and air-conditioning, it is desirable that a kinetic viscosity at 40° C. of the refrigerating machine oil basis is within the range of 25 to 120 mm²/s, and the kinetic viscosity at 40° C. of the additive polyol ester oil is 180 mm²/s or more.
The refrigerating and air-conditioning apparatus includes the compressor for refrigeration and air-conditioning, a heat exchanger for dissipating the heat of the charged refrigerant discharged from the compressor for refrigeration and air-conditioning, a pressure reducing unit for reducing the pressure of the charged refrigerant flowed from the heat exchanger, and a heat exchanger for heating the charged refrigerant reduced in pressure in the pressure reducing unit.
In the refrigerating and air-conditioning apparatus, it is desirable that a kinetic viscosity at 40° C. of the refrigerating machine oil basis is 25 to 120 mm²/s, and the adsorption capability of the additive polyol ester oil to an iron-based material is two or more times higher than that of the refrigerating machine oil basis.
The compressor for refrigeration and air-conditioning is charged with a mixture including a refrigerant for refrigeration and air-conditioning which is a refrigerant having a global warming potential of 1000 or less, or R410A; and a refrigerating machine oil including a refrigerating machine oil basis including at least one base oil selected from the group consisting of polyol ester oils expressed by the following chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), the refrigerating machine oil basis having a kinetic viscosity at 40° C. of 25 to 120 mm²/s; and an additive polyol ester oil expressed by the following chemical formula (3) (where in the formula, R₂represents an alkyl group having 7 to 9 carbon atoms).
The composition of the additive polyol ester oil is desirably 1 to 30 wt %.
The compressor for refrigeration and air-conditioning includes a scroll or rotary closed compressor including a motor therein, and in addition, a twin rotary compressor, a two-stage compression rotary compressor, and a swing compressor including a roller and a vane integrated with each other. Desirably, the kinetic viscosity at 40° C. of the refrigerating machine oil basis is 25 mm²/s to 120 mm²/s or less, and the kinetic viscosity at 40° C. of the additive polyol ester oil is 180 mm²/s or more.
The compressor for refrigeration and air-conditioning includes a sliding part formed of an iron-based material. The contact surface pressure in the sliding part is 10 MPa or more.
In the compressor for refrigeration and air-conditioning, the additive polyol ester oil has an adsorption capability to the iron-based material two or more times higher than that of the refrigerating machine oil basis. Further, the adsorption capability of the additive polyol ester oil to the iron-based material is desirably two times higher, and further desirably 4 times higher.
The refrigerating and air-conditioning apparatus uses the scroll or rotary compressor.
Below, the present invention will be described in details by way of Examples.
Examples each disclose a compressor using 2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene, or a mixed refrigerant including these, or propane, propylene, fluoroethane, difluoromethane, or R410A as a refrigerant, and a refrigerating and air-conditioning apparatus using the compressor.
In this specification, the refrigerants for refrigeration and air-conditioning include refrigerants with a GWP of 1000 or less such as 2,3,3,3-tetrafluoropropene or 1,3,3,3-tetrafluoropropene, or a mixed refrigerant including these, or propane, propylene, fluoroethane and difluoromethane, and R410A.
The refrigerating machine oils of Examples include additive polyol ester oils with an extremely higher adsorption capability to an iron-based material than that of the base oil.
As base oils with a lower adsorption capability than that of the additive polyol ester oil, mention may be made of mineral oil, polyvinyl ether oil, and polyol ester oil having an ester group in the molecular structure.
As the mineral oils, there can be used naphthene type mineral oils and paraffin type mineral oils. As these mineral oils, mention may be made of, for example, burning oils obtained by refining distillate oils obtained by subjecting paraffinic crudes, intermediate base crudes, or naphthenic crudes to atmospheric distillation, or by subjecting atmospherically distilled residual oils to vacuum distillation according to the ordinary methods, deeply dewaxed oils obtained by further performing a deep dewaxing treatment after refining, and hydrogen-treated oils obtained by a hydrogen treatment. The refining methods at the steps have no particular restriction, and various methods are used.
The polyol ester oil is obtained from the condensation reaction between polyhydric alcohol and monohydric fatty acid.
The polyol ester oils are preferably of hindered type excellent in thermal stability. Preferred examples of polyhydric alcohols include neopentyl glycol, trimethylolpropane and pentaerythritol.
Monohydric fatty acids include n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, 3,5,5-trimethylhexanoic acid and the like. These are used alone, or in mixture of two or more thereof.
The additive polyol ester oils with a high adsorption capability to an iron-based material are desirably polyol ester oils including ester groups in a large amount in the molecular structure. Mention may be made of dipentaerythritol of a hindered type synthesized from polyhydric alcohol and monohydric fatty acid.
Monohydric fatty acids include n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, 2-methylbutanoic acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, isooctanoic acid, 3,5,5-trimethylhexanoic acid and the like. These are used alone, or in mixture of two or more thereof.
The viscosity grade of each refrigerating machine oil for use in the air-conditioning apparatuses and the refrigerating machines of Examples varies according to the type of the compressor. However, the kinetic viscosity at 40° C. is preferably within the range of 46 to 120 mm²/s in a scroll compressor. Whereas, the kinetic viscosity at 40° C. is preferably within the range of 25 to 70 mm²/s in a rotary compressor.
The heat resistance class of electrical insulation is specified according to the heat resistance class of electrical insulation and the heat resistance evaluation JEC-6147 (The Institute of Electrical Engineers of Japan, Japanese Electrotechnical Committee Standard). The insulation materials adopted for compressors for refrigeration and air-conditioning are also selected according to the heat resistance class of the standard. However, in the case of the organic insulating materials for the refrigerating and air-conditioning system, the insulating materials are used in specific environment such as in a refrigerant atmosphere. Therefore, it is necessary to consider the inhibition of deformation and alternation due to pressure other than temperature. Further, the insulating materials are also in contact with polar compounds such as refrigerants or refrigerating machine oils. Therefore, a consideration must be also given to solvent resistance, extraction resistance, stabilities concerning thermal, chemical and mechanical properties, refrigerant resistance (crazing (minute pleated crack formed upon immersion in a refrigerant after applying a stress to the film), blister (bubble in a film caused by temperature rising of the refrigerant absorbed in the film)), and the like.
For this reason, it is necessary to use an insulating material of a high heat resistance class (class E 120° C. or more).
The insulating material most frequently used in a compressor is PET (polyethylene terephthalate). As the uses thereof, a film material is used for coil insulation from the iron core of a distributed winding motor. Fibrous PET is used for the covering material of the coil binding thread and the lead wire of the motor.
As other insulation film than this, mention may be made of PPS (polyphenylene sulfide), PEN (polyethylene naphthalate), PEEK (polyether ether ketone), PI (polyimide), PA (polyamide) and the like.
Further, for the main insulation covering materials of the coil, there are used THEIC-modified polyester, polyamide, polyamideimide, polyesterimide, polyesteramideimide and the like. A double covered copper wire subjected to double coating of polyesterimide-amideimide is preferably used.
It does not matter at all if an extreme-pressure additive, an oxidation inhibitor, an acid scavenger, a defoamer, a metal deactivator, and the like are added to the refrigerating machine oil. Particularly, the polyol ester oil undergoes degradation caused by hydrolysis in the presence of moisture. Therefore, mixing of the oxidation inhibitor and the acid scavenger is essential.
The oxidation inhibitor is preferably DBPC (2,6-di-t-butyl-p-cresol) of a phenol type.
As the acid scavengers, there are generally used aliphatic epoxy type compounds and carbodiimide type compounds as compounds having epoxy rings. Particularly, the carbodiimide type compounds are high in reactivity with fatty acids, and trap hydrogen ions dissociated from fatty acids. Accordingly, the effect of inhibiting the hydrolysis reaction of the polyol ester oil is very large.
As the carbodiimide type compound, mention may be made of bis (2,6-isopropylphenyl) carbodiimide. The amount of the acid scavenger to be added is preferably set at 0.05 to 1.0 wt % based on the amount of the refrigerating machine oil.
Incidentally, an extreme pressure agent may generally be mixed in the refrigerant for use in a compressor. As the extreme pressure agents, there are conventionally used tertiary phosphates such as tricresyl phosphate and triphenyl phosphate.
In the compressor for refrigeration and air-conditioning of the present invention it is possible to improve the wear resistance by using the refrigerants and the refrigerating machine oils. This eliminates the necessity of using an extreme pressure agent.

Examples 1 to 12

(Refrigerating Machine Oil Component)
For the enhancement of efficiency of the compressor for refrigeration and air-conditioning, the dissolved viscosity of the refrigerant and the refrigerating machine oil in a mutually dissolved state (which will be hereinafter simply referred to as “dissolved viscosity”) is the important factor.
A refrigerant whose lower critical solution temperature at which liquid-liquid double layer separation starts to occur at low temperatures is −30° C. or less and a refrigerating machine oil are combined. In this case, the refrigerant is dissolved in a large amount in the refrigerating machine oil according to the compressor operation conditions. Accordingly, the dissolved viscosity is largely reduced. When the dissolved viscosity in the compressor is low, not only the compression part sealing property is reduced, but also the oil film strength at the compressor sliding part is reduced. Accordingly, wear proceeds, resulting in degradation of the reliability of the refrigerating and air-conditioning apparatus. For this reason, the adsorption property of the refrigerating machine oil component to the sliding part becomes an important parameter.
The large part of the sliding part includes an iron-based material, and on the surface thereof, iron oxide is formed.
The adsorption capability of the refrigerating machine oil to an iron-based material in this specification is substantially considered as the adsorption capability of the refrigerating machine oil to iron oxide.
Based on this point of view, in the present example, using a Fe₃O₄(triiron tetroxide) powder (specific surface area 1.57 m²/g) with a mean particle size of 1 μm, the adsorption capability of the refrigerating machine oil was evaluated.
The concentrations of the refrigerating machine oil component diluted with a solvent before and after adsorption were quantified by nuclear magnetic resonance spectrometry (NMR). Thus, the amount of the component adsorbed to the iron oxide powder was calculated. Hexane was used as the solvent, and adjustment was performed such that each refrigerating machine oil component was 0.3 mol-ppm. Into a 20-ml screw tube, the iron oxide powder was collected in an amount of 3 g. Then, a solution of the refrigerating machine oil components was charged in an amount of 10 g. The solution was dispersed for 30 minutes in an ultrasonic washer, and was allowed to stand for 48 hours. Then, the supernatant liquid was subjected to 1H-NMR analysis.
Herein, mol-ppm is ppm (parts per million) based on moles. Namely, mol-ppm is ppm calculated with the number of moles of the solution (mixture of solvent and solute) as the denominator and with the number of moles of the solute as the numerator.
The base oil used as the refrigerating machine oil component is as follows. Herein, the 40° C. kinetic viscosity means the kinetic viscosity at 40° C.
(A) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil of pentaerythritol type 2-methylhexanoic acid/2-ethylhexanoic acid): 40° C. kinetic viscosity 31.8 mm²/s;
(B) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil of neopentyl glycol/pentaerythritol type 2-ethylhexanoic acid/3,5,5-trimethylhexanoic acid): 40° C. kinetic viscosity 46.9 mm²/s;
(C) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil of neopentyl glycol/pentaerythritol type 2-ethylhexanoic acid/3,5,5-trimethylhexanoic acid): 40° C. kinetic viscosity 64.8 mm²/s;
(D) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil of pentaerythritol type 2-ethylhexanoic acid/3,5,5-trimethylhexanoic acid); 40° C. kinetic viscosity 91.3 mm²/s;
(E) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil of dipentaerythritol type 2-ethylhexanoic acid/3,5,5-trimethylhexanoic acid): 40° C. kinetic viscosity 190 mm²/s;
(F) Hindered type polyol ester oil (POE) (mixed fatty acid ester oil of dipentaerythritol type 2-ethylhexanoic acid/3,5,5-trimethylhexanoic acid): 40° C. kinetic viscosity 217 mm²/s;
(G) Hindered type polyol ester oil (POE) ( dipentaerythritol type 3,5,5-trimethylhexanoic acid ester oil): 40° C. kinetic viscosity 417 mm²/s;
(H) Polyvinyl ether oil (PVE): 40° C. kinetic viscosity 50.1 mm²/s;
(I) Polyvinyl ether oil (PVE): 40° C. kinetic viscosity 65 mm²/s;
(J) Polyalkylene glycol oil (PAG) (polypropylene glycol dimethyl ether): 40° C. kinetic viscosity 112 mm²/s;
(K) Naphthene type mineral oil: 40° C. kinetic viscosity 54.1 mm²/s; and
(L) Poly-alpha-olefin oil: 40° C. kinetic viscosity 61.8 mm²/s
The results of measurement of the adsorption amount of each compound to the iron oxide powder are shown in Table 1.

TABLE 1

Refrigerating	40° C. kinetic	Iron oxide	Initial	Post-adsorption	Adsorption
machine oil	viscosity	amount	concentration	concentration	amount
component	(mm²/s)	(g)	(mol-ppm)	(mol-ppm)	(mol/m²)

Example	1	A	31.8	3.0	0.30	0.255	4.85 × 10⁸
	2	B	46.9	3.0	0.30	0.250	5.39 × 10⁸
	3	C	64.8	3.0	0.30	0.260	4.31 × 10⁸
	4	D	91.3	3.0	0.30	0.265	3.77 × 10⁸
	5	E	190	3.0	0.30	0.110	2.05 × 10⁻⁷
	6	F	217	3.0	0.30	0.110	2.05 × 10⁻⁷
	7	G	417	3.0	0.30	0.130	1.83 × 10⁻⁷
	8	H	50.1	3.0	0.30	0.280	2.16 × 10⁻⁸
	9	I	65	3.0	0.30	0.280	2.16 × 10⁻⁸
	10	J	112	3.0	0.30	0.280	2.16 × 10⁻⁸
	11	K	54.1	3.0	0.30	0.290	1.08 × 10⁻⁸
	12	L	61.8	3.0	0.30	0.290	1.08 × 10⁻⁸

Each compound shows a different adsorption amount to the iron oxide powder (adsorption capability). It is indicated that the polar compounds are more likely to be adsorbed to the iron-based material.
It is indicated that the compounds (E), (F) and (G) each including a large amount of ester groups present in the molecular structure particularly exhibit a large adsorption amount in the polar compounds. Namely, the compounds (E), (F) and (G) are 2.0 or more times higher in adsorption capability to an iron-based material (iron oxide) than other refrigerating machine oil components (A) to (D) and (H) to (L).
This indicates that the refrigerating machine oil components (E), (F) and (G) each tend to form a film at the compressor sliding part.
This is considered to be due to the following reason.
The oxygen of carbonyl (C=0) included in an ester group tends to be negatively charged. In contrast, the surface of iron oxide is generally hydrated to be in a structure having a hydroxyl group. For this reason, the attractive force due to the Coulomb force is generated between the hydrogen included in the hydroxyl group in the surface of the iron oxide and the oxygen included in the ester group, which facilitates adsorption.
From the results, (E), (F) and (G) were determined to be used as additive polyol ester oils in the present invention.

Examples 13 to 25

A refrigerant and a refrigerating machine oil are charged in the compressor for refrigeration and air-conditioning.
The compatibility between the refrigerant and the refrigerating machine oil is one of important characteristics in terms of ensuring the reliability of the compressor such as oil return from the refrigeration cycle to the compressor (ensuring the oil amount inside the compressor) or reduction of the heat exchange efficiency. However, the dissolved viscosity of the liquid mixture largely varies according to the amount of the refrigerant dissolved in the refrigerating machine oil due to the presence of the refrigerant. A large dissolution amount results in a remarkable reduction of the viscosity of the oil. Accordingly, a sufficient oil film strength cannot be obtained at the sliding part. Further, the function as the sealing material of the compression part is impaired.
The compatibility between the refrigerant and the refrigerating machine oil was evaluated and measured according to JIS K 2211.
In a pressure resistant glass container, the refrigerant was charged at a given oil concentration. Thus, the temperature was changed to observe the contents. At this step, when the contents became whitish, the contents were determined as having undergone two-layer separation. For transparency, the contents were determined as having undergone dissolution. The oil concentration dependency of the temperature at which two-layer separation occurs is generally a curve having a maximum value. This maximum value is referred to as a lower critical solution temperature. The lower critical solution temperature is a parameter indicating the degree of the compatibility between the refrigerant and the refrigerating machine oil.
The refrigerating machine oil compatible with each refrigerant was selected. Thus, the results of measurement of the lower critical solution temperature are shown in Table 2.

TABLE 2

		40° C.
	Refrigerating	kinetic	Lower critical
	machine oil	viscosity	solution
Refrigerant	component	(mm²/s)	temperature

Example	13	HFO1234yf	C	64.8	−60° C. or less
	14	HFO1234yf	I	65	−60° C. or less
	15	Propane	C	64.8	−60° C. or less
	16	Propane	K	54.1	−60° C. or less
	17	Propylene	C	64.8	−60° C. or less
	18	Propylene	K	54.1	−60° C. or less
	19	HFC161	C	64.8	−60° C. or less
	20	HFC161	I	65	−60° C. or less
	21	HFC161	K	54.1	−40° C.
	22	HFC32	C	64.8	20° C. or more
	23	HFC32	I	65	20° C. or more
	24	R410A	C	64.8	9° C.
	25	R410A	I	65	−47° C.

The lower critical solution temperature largely varies according to the degree of compatibility between the refrigerant and the refrigerating machine oil. Particularly, when HFO1234yf, propane, propylene or fluoroethane is used as the refrigerant, the solubility in the refrigerating machine oil is very high, which causes a large reduction of the viscosity in the operation conditions of the compressor. Generally, the viscosity grade of the refrigerating machine oil is increased to take countermeasures thereagainst. However, the amount of the refrigerant dissolved increases according to the temperature and pressure in the operation conditions of the compressor for refrigeration and air-conditioning. Accordingly, in actuality, the viscosity does not increase largely.

Examples 26 to 31 and Comparative Examples 1 to 6

Using a shell type four-ball friction-wear tester, the lubricity of the refrigerating machine oil was evaluated.
Using a ½-inch SUJ2 steel ball as a specimen, the wear scar diameter (average of 3 balls) and the coefficient of friction of each fixed specimen after performing the test under load: 280 N, temperature: 120° C., rotation speed: 1200 min⁻¹, and time: 10 min were measured.
As the refrigerating machine oil bases, there were used the polyol ester oils (A) to (D), the polyvinyl ether oil (I), and the naphthene type mineral oil (K). The mixtures obtained by adding the additive polyol ester oil (F) in an amount of 5.0 wt % thereto were evaluated.
As Comparative Examples, evaluation was made on the cases of the polyol ester oils (A) to (D) used alone, the case of the polyvinyl ether oil (I) used alone, and the case of the naphthene type mineral oil (K) used alone.
The results of evaluation of the lubricity of each refrigerating machine oil are shown in Table 3.

TABLE 3

Refrigerating	40° C.
machine oil	kinetic	Wear scar
component	viscosity	diameter	Coefficient

	Basis	Additive	(mm²/s)	(mm)	of friction

Example	26	A	F (5 wt %)	34.7	0.57	0.23
	27	B	F (5 wt %)	50.4	0.51	0.22
	28	C	F (5 wt %)	68.6	0.49	0.23
	29	D	F (5 wt %)	95.2	0.48	0.21
	30	I	F (5 wt %)	68.9	0.46	0.18
	31	K	F (5 wt %)	57.5	0.45	0.18
Compar-	1	A	None	31.8	0.62	0.36
ative	2	B	None	46.9	0.57	0.35
Example	3	C	None	64.8	0.58	0.35
	4	D	None	91.3	0.55	0.33
	5	I	None	65	Seizure	Seizure
					occurred	occurred
	6	K	None	54.1	Seizure	Seizure
					occurred	occurred

The results indicate the following: for the refrigerating machine oils not including the additive polyol ester oil (F) mixed therein of Comparative Examples 1 to 4, each wear scar diameter is large, and each coefficient of friction is high; for Comparative Examples 5 and 6, the test was stopped because of the occurrence of seizure immediately after the start of the test.
In contrast, for the refrigerating machine oils each including the additive polyol ester oil (F) mixed therein shown in Examples 26 to 31, each wear scar diameter and each coefficient of friction were suppressed regardless of the oil species of the refrigerating machine oil basis. Thus, the lubricity improving effect was produced. This is due to the following fact. The adsorption capability of the additive polyol ester oil (F) to the iron-based material is larger than that of the refrigerating machine oil basis. Accordingly, the friction surface was rendered in a low surface energy state. This produced the wear resistance and an effect of reducing the coefficient of friction. Also when the refrigerating machine oil bases were the polyvinyl ether oil (I) and the naphthene type mineral oil (K), seizure did not occur. Particularly, when the refrigerating machine oil basis is the polyvinyl ether oil (I) or the naphthene type mineral oil (K) exhibiting a smaller adsorption amount than that of the additive polyol ester oil (F) as shown in Table 1, the additive polyol ester oil (F) becomes more likely to be adsorbed on the friction surface. For this reason, the lubricity improving effect tends to be produced.

Examples 32 to 37 and Comparative Examples 7 to 8

In order to observe the effects of the additive polyol ester oils (E) and (G), the same test as in Example 26 was performed using the shell type four-ball friction-wear tester, except for changing the type and the addition amount of the additive polyol ester oil.
The results of evaluation of the lubricity of each refrigerating machine oil are shown in Table 4.

TABLE 4

Refrigerating	40° C.
machine oil	kinetic	Wear scar	Co-
component	viscosity	diameter	efficient

	Basis	Additive	(mm²/s)	(mm)	of friction

Example	32	C	F (1 wt %)	65.5	0.52	0.23
	33	C	F (10 wt %)	72.7	0.48	0.22
	34	C	F (20 wt %)	81.7	0.49	0.23
	35	C	F (30 wt %)	91.9	0.48	0.21
	36	C	E (5 wt %)	68.2	0.51	0.25
	37	C	G (5 wt %)	70.6	0.52	0.25
Compar-	7	C	F (0.1 wt %)	64.9	0.58	0.35
ative	8	C	F (0.5 wt %)	65.2	0.57	0.33
Example

For the refrigerating machine oils of Examples 32 to 37 shown in this table, as compared with the refrigerating machine oil using (C) as the refrigerating machine oil basis, and not including an additive added thereto of Comparative Example 3 (shown in Table 3), the wear scar diameter and the coefficient of friction were suppressed. Thus, it was possible to observe the lubricity improving effect.
Whereas, in the cases of Comparative Examples 7 and 8 each having a small amount of the additive polyol ester oil (F) added therein, each wear scar diameter is large, and each coefficient of friction is high. Accordingly, the lubricity improving effect is less likely to be exerted. In contrast, for the refrigerating machine oils in each of which the additive polyol ester oil (F) is added in an amount of 1.0 wt % or more based on the amount of the refrigerating machine oil basis shown in Examples 32 to 35, each wear scar diameter and each coefficient of friction are suppressed. This produced the lubricity improving effect.

Examples 38 and 39, Comparative Examples 9 and 10

FIG. 1 shows the outline of a dual-purpose cooling/heating room air conditioner used in the present Examples.
When an inside of a room is cooled, a high-temperature high-pressure refrigerant gas (charged refrigerant) adiabatically compressed through a discharge pipe of a compressor 1 passes through a four-way valve 2 to be cooled in an outdoor heat exchanger 3 (used as a condensing means), resulting in a high-pressure liquid refrigerant. The refrigerant is expanded in an expansion means 4 (such as a capillary tube or a temperature type expansion valve, which is also referred to as a pressure reducing unit), resulting in a low-temperature low-pressure solution slightly containing a gas. The solution reaches the indoor heat exchanger 5 (used as an evaporation means), and gets heat from the air inside the room, resulting in a low-temperature gas form. The resulting gas passes through the four-way valve 2 again, and reaches the compressor 1. When the inside of the room is heated, the flow of the refrigerant is changed to the opposite direction by the four-way valve 2, resulting in the adverse effect. In the present example, a scroll compressor was used as the compressor.
FIG. 2 shows the schematic structure thereof.
In the compressor, a spiral wrap 8 standing upright on an end plate 7 of a fixed scroll member 6, and a rotary scroll member 9 having a wrap 10 in substantially the same shape as that of the fixed scroll member 6 are engaged with the wrap 8 and the wrap 10 facing each other. As a result, a compression mechanism part is formed. And the rotary scroll member 9 is caused to undergo rotary movement by a crank shaft 11. A compression chamber situated on the outermost side of compression chambers 12 a and 12 b formed by the fixed scroll member 6 and the rotary scroll member 9 moves toward the central part formed of the fixed scroll member 6 and the rotary scroll member 9 while gradually shrinking in volume with the rotary movement. When the compression chambers 12 a and 12 b reach the vicinity of the central part including the fixed scroll member 6 and the rotary scroll member 9, the compression chambers 12 a and 12 b communicate with the discharge port 13. Accordingly, the compressed gas in the compression chambers 12 a and 12 b is discharged through the discharge pipe 16 to the outside of the compressor.
In the compressor of the present example, an electric motor 17 is included in a pressure vessel 15. Thus, the compressor performs a compression operation by rotation of the crank shaft 11 at a given constant speed or at a rotation speed according to the voltage controlled by an inverter not shown. Further, an oil reservoir part 20 is provided below the motor 17. The oil in the oil reservoir part 20 passes through an oil path 19 provided in the crank shaft 11 due to the difference in pressure, and is subjected to lubrication of the sliding part between the rotary scroll member 9 and the crank shaft 11, a sliding bearing 18 and the like.
In Examples 38 and 39 and Comparative Examples 9 and 10, the indoor unit was set in a thermostatic chamber (35° C., humidity 75%) to perform an actual equipment test of 2160-hour operation using the room air conditioner shown in FIG. 1.
A heat-resistant PET film (type B 130° C.) was used for coil insulation from the iron core of the motor 17. There was used a double covered copper wire subjected to double coating of polyesterimide-amideimide for coil main insulation.
For evaluation of the room air conditioner, attention was given to the wear state of the scroll compressor. Thus, there was measured the clearance increment due to wear from the frame 14 to the crank shaft 11 (between the frame 14 and the crank shaft 11) before and after the test. A larger clearance increment from the frame 14 to the crank shaft 11 (which will be hereinafter also referred to as between the frame and the shaft) indicates a larger wear amount. Generally, as the clearance increment increases, vibration and noise increase.
HFO1234yf (2,3,3,3-tetrafluoropropene) was used alone as the refrigerant. The HFO1234yf is a low-pressure refrigerant. The amount of circulating refrigerant is small, resulting in an increase in pressure loss in piping. For this reason, evaluation was conducted in the following manner: the displacement amount of the compressor was set at two times higher than usual, and the diameter of the connection piping was increased, and the number of paths of the heat exchanger was increased; thus, the distribution balance was adjusted.
In a refrigerating and air-conditioning cycle using HFO1234yf and HFO1234ze, and a mixed refrigerant including these, the compatibility between the refrigerant and the refrigerating machine oil becomes an important characteristic for ensuring the amount of oil to be returned to the compressor. In the refrigerating and air-conditioning cycle, it is necessary that the refrigerating machine oil also circulates as with the refrigerant. When the compatibility is inferior, the refrigerating machine oil discharged by a mechanical element from the compressor does not circulate. Accordingly, the oil separated particularly at the low-temperature part is retained, resulting in a smaller oil amount of the compressor. This hinders the lubricating oil of the sliding part. For this reason, it is preferable that the refrigerant and the refrigerating machine oil are dissolved within the operating condition temperature range in the cycle.
With respect to HFO1234yf, hydrocarbon oils such as naphthene type mineral oils, paraffin type mineral oils, alkylbenzene oils and poly-alpha-olefin oils are less likely to be miscible. Therefore, a polyol ester oil or a polyvinyl ether oil is preferable.
In Example 38, evaluation was performed using the refrigerating machine oil ((C)+(F)) adopted in Example 28 having compatibility with HFO1234yf. Whereas, in Example 39, evaluation was performed using the refrigerating machine oil ((I)+(F)) adopted in Example 30.
As the refrigerating machine oil basis, the oil (C) or (I) was used. The oil (F) having a high adsorption capability thereto is mixed in an amount of 5 wt % therein. Thus, there was carried out a test with a refrigerating machine oil having a kinetic viscosity at 40° C. set at 68.6 mm²/s or 68.9 mm².
In Comparative Examples 9 and 10, the test was carried out with only the refrigerating machine oil bases in each of which the additive polyol ester oil in Examples 38 and 39 was not added.
As the target value of this test, the clearance increment due to wear between the frame and the shaft after the test is 10 μm or less.
The results of Examples 38 and 39 and Comparative Examples 9 and 10 are shown in Table 5.

TABLE 5

Refrigerating
machine oil	40° C. kinetic	Sliding bearing
component	viscosity	Clearance	Cooling intermediate conditions

	Refrigerant	Basis	Additive	(mm²/s)	increment (μm)	Viscosity (mPa · s)	COP(%)

Example	38	HFO1234yf	C	F (5 wt %)	68.6	3	1.8	101 (Ratio based
								on reference 1)
	39	HFO1234yf	I	F (5 wt %)	68.9	4	2.2	101.5 (Ratio based
								on reference 1)
	40	R290	C	F (5 wt %)	68.6	5	2.0	102 (Ratio based
								on reference 2)
	41	R290	K	F (5 wt %)	57.5	6	1.5	101 (Ratio based
								on reference 2)
	42	R410A	C	F (5 wt %)	68.6	2	3.8	101 (Ratio based
								on reference 3)
Comparative	9	HFO1234yf	C	None	64.8	12	1.2	100 (Reference 1)
Example	10	HFO1234yf	I	None	65	18	1.3	100 (Ratio based
								on reference 1)
	11	R290	C	None	68.6	15	1.1	100 (Reference 2)
	12	R290	K	None	57.5	24	0.9	98 (Ratio based
								on reference 2)
	13	R410A	C	None	68.6	8	3.7	100 (Reference 3)

As apparent from Table 5, for the room air conditioners of Examples 38 and 39, as compared with Comparative Examples 9 and 10, the frame-shaft clearance increment can be largely reduced. Accordingly, wear is inhibited. As a result, high reliability can be obtained in the room air conditioner.
Further, in Table 5, regarding each combination of the refrigerants and the refrigerating machine oils, the measurement results of the viscosity and an efficiency in a cooling intermediate conditions are also shown.
For the measurement of the viscosity, a piston type viscometer from Japan Controls Co., Ltd. was used.
Further, the efficiency is expressed as the ratio using Coefficient of Performance (COP) with Comparative Example 9 as the reference (100).
The results indicate as follows. In Comparative Examples 9 and 10, reduction of the viscosity occurred, so that a sufficient sealing property could not be obtained at the compression part. In contrast, the viscosity increased in Examples 38 and 39.
Further, as shown in Examples 28 and 30 of Table 3, the friction inhibiting effect due to the additive polyol ester oil was exhibited. Accordingly, the coefficient of performance was improved as compared with Comparative Example 9 (reference From the results of Examples up to this point, it has been indicated that there can be obtained a refrigerating and air-conditioning apparatus capable of inhibiting wear of the compressor, and sufficiently ensuring the long-term insulation reliability.
Further, although not shown, evaluation was performed by the same actual equipment test with a combination of a mixed refrigerant of HFO1234yf and HFC32 (20 wt % and 40 wt %) for the refrigerant and the refrigerating machine oil ((C)+(F)) adopted in Example 28. As a result, roughly the same results as those of Examples 38 and 39 were obtained. This has indicated that even use of a mixed refrigerant can produce effects, and produces no problem.

Examples 40 to 42 and Comparative Examples 11 to 13

In Examples 40 to 42, propane and R410A were used for the refrigerant. Thus, refrigeration cycles in accordance with respective refrigerants were prepared to perform the same actual equipment test as that of Example 38.
In Example 40, there were used propane as the refrigerant, and a refrigerating machine oil including the oil (C) as the refrigerating machine oil basis, and the oil (F) as an additive polyol ester oil mixed in an amount of 5.0 wt % therein.
In Example 41, there were used propane as the refrigerant, and a refrigerating machine oil including the oil (K) as the refrigerating machine oil basis, and the oil (F) as an additive polyol ester oil mixed in an amount of 5.0 wt % therein.
In Example 42, there were used R410A as the refrigerant, and a refrigerating machine oil including the oil (C) as the refrigerating machine oil basis, and the oil (F) as an additive polyol ester oil mixed in an amount of 5.0 wt % therein. In Comparative Examples 40 to 42, evaluations were respectively made on the refrigerating machine oils each not including the additive polyol ester oil added therein.
The evaluation results are shown in Table 5.
Propane has a high solubility in polyol ester oil, mineral oil or the like as shown in the evaluation results of the compatibility of Table 2. This causes a large reduction of viscosity in the compressor. Further, propane does not contain a halogen atom in the molecular structure, and hence does not form iron halide contributing to the lubricity at a friction-generating site. This results in a large increase in clearance increment due to friction between the frame and the shaft as shown in Comparative Examples 11 and 12.
In contrast, as shown in Examples 40 and 41, for the combination including the additive polyol ester oil (F) mixed to the refrigerating machine oil basis, the clearance increment due to the wear between the frame and the shaft was largely reduced, resulting in ease of friction. As a result, the Coefficient of Performance (COP) improved as compared with Comparative Example 11 (reference 2).
Further, in Example 42 using R410A as the refrigerant, as compared with Comparative Example 13 (reference 3), the clearance increment due to the wear between the frame and the shaft was suppressed, and the Coefficient of Performance (COP) also improved.
This indicates that even refrigerants such as difluoromethane, fluoroethane and propylene can provide the same effects regardless of the type of the refrigerant.
Other than these, the same effects can also be produced by a rotary compressor, a twin rotary compressor, a two-stage compression rotary compressor, and a swing compressor including a roller and a vane integrated with each other.
The present invention is applicable to a refrigerant compressor for a refrigerating and air-conditioning apparatus, and a refrigerating and air-conditioning apparatus.

Claims

1. A compressor for refrigeration and air-conditioning, comprising a mixture charged therein,

the mixture comprising:

a charged refrigerant which is a refrigerant including 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene or difluoromethane, or R410A; and

a refrigerating machine oil comprising a refrigerating machine oil basis including at least one base oil selected from the group consisting of polyol ester oils expressed by the following chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), and an additive polyol ester oil expressed by the following chemical formula (3) (where in the formula, R₂represents an alkyl group having 7 to 9 carbon atoms), a composition of the additive polyol ester oil being 1 to 30 wt %.

2. The compressor according to claim 1, wherein a kinetic viscosity at 40° C. of the refrigerating machine oil basis is within the range of 25 to 120 mm²/s, and the kinetic viscosity at 40° C. of the additive polyol ester oil is 180 mm²/s or more.

3. A refrigerating and air-conditioning apparatus comprising the compressor according to claim 1, a heat exchanger for dissipating the heat of the charged refrigerant discharged from the compressor, a pressure reducing unit for reducing the pressure of the charged refrigerant flowed from the heat exchanger, and a heat exchanger for heating the charged refrigerant reduced in pressure in the pressure reducing unit.

4. The refrigerating and air-conditioning apparatus according to claim 3, wherein an adsorption capability of the additive polyol ester oil to an iron-based material is two or more times higher than that of the refrigerating machine oil basis.

5. A compressor for refrigeration and air-conditioning, comprising a mixture charged therein,

the mixture comprising:

a charged refrigerant which is a refrigerant including 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, propane, propylene or fluoroethane; and

a refrigerating machine oil comprising a refrigerating machine oil basis including mineral oils or polyvinyl ether oils, or at least one base oil selected from the group consisting of polyol ester oils expressedby the following chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), the refrigerating machine oil basis having a lower critical solution temperature of −30° C. or less, and an additive polyol ester oil expressed by the following chemical formula (3) (where in the formula, R₂represents an alkyl group having 7 to 9 carbon atoms), a composition of the additive polyol ester oil being 1 to 30 wt %.

6. The compressor according to claim 5, wherein a kinetic viscosity at 40° C. of the refrigerating machine oil basis is within the range of 25 to 120 mm²/s, and the kinetic viscosity at 40° C. of the additive polyol ester oil is 180 mm²/s or more.

7. A refrigerating and air-conditioning apparatus comprising the compressor according to claim 5, a heat exchanger for dissipating the heat of the charged refrigerant discharged from the compressor, a pressure reducing unit for reducing the pressure of the charged refrigerant flowed from the heat exchanger, and a heat exchanger for heating the charged refrigerant reduced in pressure in the pressure reducing unit.

8. The refrigerating and air-conditioning apparatus according to claim 7, wherein an adsorption capability of the additive polyol ester oil to an iron-based material is two or more times higher than that of the refrigerating machine oil basis.

9. A compressor for refrigeration and air-conditioning comprising a mixture charged therein,

the mixture comprising:

a refrigerant for refrigeration and air-conditioning which is a refrigerant with a global warming potential of 1000 or less, or R410A; and

a refrigerating machine oil comprising a refrigerating machine oil basis including at least one base oil selected from the group consisting of polyol ester oils expressed by the following chemical formulae (1) and (2) (where in the formulae, R₁represents an alkyl group having 5 to 9 carbon atoms), the refrigerating machine oil basis having a kinetic viscosity at 40° C. of 25 to 120 mm²/s, and an additive polyol ester oil expressed by the following chemical formula (3) (where in the formula, R₂represents an alkyl group having 7 to 9 carbon atoms), a composition of the additive polyol ester oil being 1 to 30 wt %.

10. A refrigerating and air-conditioning apparatus comprising the compressor according to claim 9, a heat exchanger for dissipating the heat of the refrigerant discharged from the compressor, a pressure reducing unit for reducing the pressure of the refrigerant flowed from the heat exchanger, and a heat exchanger for heating the refrigerant reduced in pressure in the pressure reducing unit.

11. The refrigerating and air-conditioning apparatus according to claim 10, wherein an adsorption capability of the additive polyol ester oil to an iron-based material is two or more times higher than that of the refrigerating machine oil basis.