AU772143B2

AU772143B2 - Halogenated hydrocarbon refrigerant compositions containing hydrocarbon oil-return agents

Info

Publication number: AU772143B2
Application number: AU49942/99A
Authority: AU
Inventors: Donald Bernard Bivens; Barbara Haviland Minor; Hans O. Spauschus; Akimichi Yokozeki
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1999-01-15
Filing date: 1999-07-14
Publication date: 2004-04-08
Anticipated expiration: 2019-07-14
Also published as: EP1151054A1; CN1333806A; CA2359090A1; WO2000042118A1; JP2002534578A; AU4994299A; BR9917321A; CN1210368C

Description

WO 00/42118 PCT/US99/15935

TITLE

HALOGENATED HYDROCARBON REFRIGERANT

COMPOSITIONS

CONTAINING HYDROCARBON OIL-RETURN

AGENTS

FIELD OF THE INVENTION The present invention relates to refrigerant compositions containing hydrocarbon oil-return agents which solubilize mineral and synthetic oil lubricants with halogenated hydrocarbon refrigerants, thereby permitting efficient return of lubricants from non-compressor zones back to a compressor zone in a refrigeration system.

BACKGROUND

Mineral oils and alkylbenzenes have been conventionally used as lubricants in chlorofluorocarbon-based (CFC) refrigeration systems. However, the lack of solubility of these lubricants in the replacement, non-ozone depleting, hydrofluorocarbon (HFC) refrigerants has precluded their use and necessitated development and use of alternative lubricants for HFC refrigeration systems based on polyalkylene glycols (PAGs) and polyol esters (POEs). While the PAGs and POEs are suitable lubricants for HFC-based refrigeration systems, they are extremely hygroscopic and can absorb several thousand ppm (parts per million) of water on exposure to moist air. This absorbed moisture leads to problems in the refrigeration system, such as formation of acids which resultant in corrosion of the refrigeration system and formation of intractable sludges. In contrast, mineral oils and alkylbenzenes are much less hygroscopic and have low solubility, less than 100 ppm, for water. Additionally, PAG and POE lubricants are considerably more expensive than the hydrocarbon lubricants, typically on the order of three to six times more expensive. As a consequence, there is a need and an opportunity to resolve this solubility problem so that the refrigeration industry may utilize mineral oil and alkylbenzene lubricants with HFC-based refrigerants.

Hydrochlorofluorocarbon (HCFC) refrigerants are also replacing CFCs, and in instances as mixtures with HFCs. These HCFC-based refrigerant mixtures are less soluble than CFCs in conventional refrigeration lubricants such as mineral oil. A lubricant change from mineral oil to alkylbenzene is often required when the HCFCs or HCFC/HFC mixtures are used to replace pure CFCbased refrigerants, resulting in more expense to the refrigeration industry.

Consequently, there is a need and opportunity to resolve this low solubility problem so that the refrigeration industry may utilize HCFC and HCFC/HFC-based refrigerants with mineral oil lubricants.

For the foregoing reasons there is a need in the refrigeration industry for providing oil-return agents that create a solution of lubricant oil (dispersed phase) in a HFC- and/or HCFC-based refrigerant (continuous phase), which permits improved lubricant oil transport through a refrigeration system and lubricant oil return back to the refrigeration-system compressor from other refrigeration system zones.

SUMMARY

The present invention is directed to a refrigerant composition that satisfies the aforesaid need. In one form, the invention provides a refrigerant composition comprising: a halogenated hydrocarbon refrigerant having 1-6 carbon atoms, at least one fluorine atom and optionally chlorine and oxygen atoms, having a normal boiling point of from -90 0 C to 80 0

C;

a refrigeration oil selected from the group consisting of naphthenes, aromatics and polyalphaolefins; and a hydrocarbon oil-return agent selected from the group consisting of combustible, non-flammable hydrocarbons containing from 10 to 16 carbon atoms.

The invention also provides a process for returning oil from a non-compressor *i 20 zone to a compressor zone in a compression refrigeration system comprising: :i contacting a refrigeration oil, selected from the group consisting of naphthenes, aromatics and polyalphaolefins, in the non-compressor zone with halogenated i" hydrocarbon refrigerant having 1-6 carbon atoms, at least one fluorine atom and optionally chlorine and oxygen atoms, having a normal boiling point of from -90 0 C to 80 0 C, in the presence of a hydrocarbon oil-return agent selected from the group consisting of combustible, non-flammable aliphatic hydrocarbons containing from 10 to 16 carbon atoms, to form a solution comprising oil, refrigerant, and hydrocarbon oil return agent; and transferring the solution from the non-compressor zone to the compressor zone of the refrigeration system.

30 19 .0 30 19/02/04,atl 2120.specipgs, 14 WO 00/42118 PCT/US99/15935 DETAILED DESCRIPTION The present invention relates to refrigerant compositions comprising: a halogenated hydrocarbon containing at least one carbon atom and one fluorine atom; an oil selected from the group consisting of mineral oils and synthetic oils; and a hydrocarbon oil-return agent containing from ten to sixteen carbon atoms, wherein said hydrocarbon oil-return agent forms a solution of said halogenated hydrocarbon and said oil.

The present invention further relates to compositions comprising: (a) a halogenated hydrocarbon containing at least one carbon atom and one fluorine atom; and a hydrocarbon oil-return agent containing from ten to sixteen carbon atoms, wherein said hydrocarbon oil-return agent forms a solution of said halogenated hydrocarbon with an oil selected from the group consisting of mineral oils and synthetic oils.

The present invention further relates to lubricant compositions for use with halogenated hydrocarbon refrigerants in compression refrigeration apparatus, comprising: an oil selected from the group consisting of mineral oils and synthetic oils; and a hydrocarbon oil-return agent containing from ten to sixteen carbon atoms, wherein said oil-return agent forms a solution of said oil with halogenated hydrocarbon refrigerant.

The present invention further relates to a process for returning oil from a non-compressor zone to a compressor zone in a compression refrigeration system comprising: contacting an oil, selected from the group consisting of mineral oils and synthetic oils, in the non-compressor zone with a halogenated hydrocarbon, containing at least one carbon atom and one fluorine atom, in the presence of a hydrocarbon oil-return agent, containing from six to sixteen carbon atoms, to form a solution comprising oil, halogenated hydrocarbon, and hydrocarbon oil-return agent; and transferring the solution from the noncompressor zone to the compressor zone of the refrigeration system.

Halogenated hydrocarbons of the present invention contain at least one carbon atom and one fluorine atom. Of particular utility are halogenated hydrocarbons having 1-6 carbon atoms containing at least one fluorine atom, optionally containing chlorine and oxygen atoms, and having a normal boiling point of from -90°C to 80 0 C. By normal boiling point is meant the temperature at which a liquid composition's vapor pressure is equal to one atmosphere. These halogenated hydrocarbons may be represented by the general formula CwF2w+2.x.yHClyOz, wherein w is 1-6, x is 1-9, y is 0-3, and z is 0-2. Preferred of the halogenated hydrocarbons are those in which w is 1-6, x is 1-5, y is 0-1, and z .WO 00/42118 PCTIUS99/1 5935 is 0-1. Such halogenated hydrocarbons are commercial products available from a number of sources such as E. I. du Pont de Nemours Co., Fluoroproducts, Wilmington, DE, 19898, USA, or are available from custom synthesis companies such as PCR Inc., P.O. Box 1466, Gainesville, Florida, 32602, USA, and additionally by synthetic processes disclosed in art such as The Journal of Fluorine Chemistry, or Chemistry of Organic Fluorine Compounds, edited by Milos Hudlicky, published by The MacMilan Company, New York, 1962.

Examples of the halogenated hydrocarbons are: CC1 2

F

2 (CFC-12), CHC1 2

F

(HCFC-2 CHCIF 2 (HCFC-22), CHF 3 (HFC-23), CH 2 CIF (HCFC-3 CH 2

F

2 (HFC-32), CH 3 F (HFC-4 CF 3

CF

3 (PC- 116), CHCl 2 CF3 (HCFC- 123), CHCIFCClF 2 (HCFC-123a), CHCIFCF 3 (LICFC-124), C1HF 2 CClF 2 (HCFC-124a),

CHF

2

CF

3 (HFC-125), CH 2 ClCF 3 (HCFC-133a),

CHF

2

CHF

2 (HC-134),

CH

2

FCF

3 (HC- 134a), CCIF 2

CH

3 (HCFC- 142b), C1HF 2

CH

2 F (HFC- 143),

CF

3

CH

3 (HFC-143a), CHCIFCH 3 (HCFC-151a), CHF 2

CH

3 (HC-152a),

CHF

2

CC

2

CF

3 (HCFC-225aa), CHClFCCIFCF 3 (HCFC-225ba), CHF 2 COlFCCIF 2 (HCFC-225bb), CHCl 2

CF

2

CF

3 (HCFC-225ca), CHClFCF 2 CClF 2 (HCFC-225cb),

CEF

2

CF

2 CCl 2 F (HCFC-225 cc), CC1F 2 CHC1CF 3 (HCFC-225da),

CCIF

2 CHFCClF 2 (HCFC-225ea), CF 3 CHFCCl 2 F (HCFC-225eb), CHF 2 CC1FCF 3 (HCFC-226ba), CHClFCF 2

CF

3 (HCFC-226ca), CBF 2

CF

2 CClF 2 (HCFC-226cb),

CF

3

CHCICF

3 (HCFC-226da), CClF 2

CH-FCF

3 (HCFC-226ea),

CHF

2

CF

2

CF

3 WHC-227ca), CF 3

CFHCF

3 (HFC-227ea),

CHF

2 CClFCHF 2 (HCFC-235ba),

CH

2 FCC1FCF 3 (HCFC-235bb),

CHCIFCF

2

CHF

2 (HCFC-235ca), CH 2 ClCF 2

CF

3 (HCFC-23 5cb), CH 2

FCF

2 CClF 2 (HCFC-23 5cc), CHF 2 CHClCF 3 (HCFC-23 Sda),

CHCIFCHFCF

3 (HCFC-23 Sea), CHF 2 CHFCC1F 2 (H1CFC-235eb), CC1F 2

CH

2

CF

3 (HCFC-235fa), CH-F 2

CF

2

CHF

2 (HFC-236ca), CH 2

,FCF

2

CF

3 (HFC-236cb),

CHF

2

CHFCF

3 (HC-236ea), CF3CH 2

CF

3 (HC-236fa), CH 2

FCF

2 CII1F 2

(HFC-

245ca), CH 3

CF

2

CF

3 (HFC-245cb), CHF 2

CBFCHF

2 (HC-245ea), CH 2

FCHFCF

3 (HC-245eb), CIF 2

CH

2

CF

3 (HFC-245fa), CH 2

FCF

2

CH

2 F (HFC-254ca),

CH

2

CF

2

CHF

2 (HFC-254cb), CH 2

FCHFCHF

2 (HC-254ea), CH 3

CHFCF

3

WHC-

254eb), CHF 2

CH

2

CHF

2 (HFC-254fa), CH 2

FCH

2

CF

3 (IHFC-254fb), CH 3

CF

2

CH

3 (HFC-272ca), CH 3

CHFCH

2 F (BFC-272ea),

CH

2

FCH

2

CH

2 F (HFC-272fa),

CH

3

CH

2

CF

2 H (HFC-272fb), CH 3

CHFCH

3 (BFC-28 lea), CH 3

CH

2

CH

2 F (B:FC- 28 ifa), CF 3

CF

2

CF

2

CF

2 H (HFC-3 29p), CF 3

CF

2

CFHCF

3 (HFC-329rne),

CF

3

CF

2

CF

2

CFH

2 (HFC-338q), CF 3

CF

2

CH

2

CF

3 (IIFC-338mf), CF 3

CF

2

CFHCF

2

H

(HFC-338pe), CF 3

CFHCF

2

CF

2 H (IIFC-338pce), CHF 2

CF

2

CF

2

CF

2 H WHC- 33 8pcc), CF 3

CFHCFHCF

3 (BFC-33 8mee), CF 3

CF

2

CF

2

CF

2

CF

2 H (HFC-42- lip),

CF

3

CF

2

CFHCF

2

CF

3 (HFC-42-1 Ilmce), CF 3

CF

2

CF

2

CFHCF

3 (IIFC-42-1 Inme),

CF

3

CF

2

CH

2

CF

2

CF

3 (HFC-43- 1 mcf), CF 3

CF

2

CF

2

CH

2

CF

3 (HFC-43 -1Omf), WO 00/42118 PCT/US99/1 5935

CF

3

CF

2

CF

2

CF

2

CFH

2 (HC-43 -1 Oq), CF 3

CF

2

CF

2

CFHCF

2 H (HFC-43- 1 pe),

CF

3

CF

2

CFHCF

2

CF

2 H (HFC-43-I1Opce),

CF

3

CHFCHFCF

2

CF

3 (HC-43- l0mee),

CF

2

HCF

2

CF

2

CF

2

CF

2 H (HC-43-1 Opccc), CF 3

CFHCF

2

CF

2

CF

2 H (HC-43- 1 Opcce), CF 3

CFHCF

2

CFHCF

3 (HC-43- l0mece), CF 3

CF

2

CF

2

CF

2

CF

2

CF

2

H

(HFC-52-13p), C 4 FqOCH 3 and C 4 Fq0C 2

H

5 Preferred of the halogenated hydrocarbons are: CHCIF 2 (HCFC-22), CHF 3 (HC-23), CH 2 1F 2 (HC-32),

CHCIFCF

3 (HiCFC-124), CHF 2

CF

3 (FC-125), CHF 2

CHF

2 (HFC-134), CH 2

FCF

3 (HC-134a), CF 3

CH

3 (IIC-143a), CHF 2

CH

3 (HC-152a), CHF 2

CF

2

CF

3

(HFC-

227ca), CF 3

CFHCF

3 (H-FC-227ea), CF 3

CH

2

CF

3 (HFC-236fa), CHF 2

CH

2

CF

3 (HC-245fa), CHF 2

CF

2

CF

2

CF

2 H (HFC-338pcc), CF 3

CHFCHFCF

2

CF

3 (HFC-43l0mee), and azeotropic and azeotrope-like halogenated hydrocarbon compositions such as: HCFC-22/IFC-152aIHCFC-124 (RL-401A, R-401B, R-401C), HIFC- 125/HFC- 143 aIHFC- 134a (R-404A), HFC-3 2/HFC- 125IHFC- 134a (R-407A, R- 407B, R-407C), HCFC-22IHFC-143aIHFC-125 (R-408A), HCFC-22/HCFC- 124/HCFC-142b (R-409A), HFC-32IHFC-125 (R-410A), and HFC-125I/iFC- 143a (R-507).

The halogenated hydrocarbons of the present invention may further comprise up to 10 weight percent of at least one C 3 to C 5 hydrocarbon, e.g., propane, propylene, cyclopropane, n-butane, i-butane, and n-pentane. Examples of halogenated hydrocarbons containing such C 3 to C5 hydrocarbons are azeotrope-like compositions of HCFC-22/HFC- 125/propane (R-402A, R-402B) and HCFC-22/octafluoropropane/propane (R-403A, R-403B).

Oils of the present invention are oils conventionally employed as lubricants in refrigeration apparatus with CFC-based refrigerants. Such oils and their properties are discussed in the 1990 ASHRAE Handbook, Refrigeration Systems and Applications, chapter 8, titled "Lubricants in Refrigeration Systems" pages 8.1-8.21. Oils of the present invention comprise the family of compounds commonly known in this field as mineral oils. Mineral oils comprise paraffins (straight-chain and branched-carbon-chain, saturated hydrocarbons), naphthenes (cycloparaffins), aromatics (unsaturated, cyclic hydrocarbons containing one or more rings characterized by alternating double bonds), and nonhydrocarbons (molecules containing atoms such as sulfur, nitrogen, or oxygen in addition to carbon and hydrogen). Oils of the present invention further comprise the family of compounds commonly known in this field as synthetic oils. Synthetic oils comprise alkylaryls (such as linear and branched-alkyl-chain alkylbenzenes), synthetic paraffins, and polyalphaoleflns. Examples of commercially available lubricant oils of the present invention are Suniso@ 3GS, Sontex® 372LT, and WO 00/42118 PCT/US99/15935 Calumet® RO-30 (all previous three being naphthenes), Zerol® 150 (an alkylbenzene), and "BVM 100 N" (a paraffin).

The hydrocarbon oil-return agents of the present invention are employed in an effective amount in the present inventive compositions such that a solution of halogenated hydrocarbon and lubricating oil is formed. By "solution" is meant that halogenated hydrocarbon and oil become more miscible in the presence of hydrocarbon oil-return agents such that oil is returned as a homogenous solution with halogenated hydrocarbon from non-compressor zones to a compressor zone in a refrigeration system in a quantity, which maintains acceptable compressor lubrication and thus overall refrigeration system operation.

In the present inventive compositions comprising halogenated hydrocarbon containing at least one carbon atom and one fluorine atom, oil selected from the group consisting of mineral oils and synthetic oils, and hydrocarbon oil-return agent, it is preferred that less than about 10 weight percent of the total composition is hydrocarbon oil-return agent. In a more preferred sense, less than about 5 weight percent of the total composition (comprising halogenated hydrocarbon, oil, and hydrocarbon oil-return agent) is hydrocarbon oil-return agent. Hydrocarbon oil-return agent concentrations greater than about 10 weight percent of the total composition are typically not needed to obtain adequate oil return and have been observed to negatively influence the viscosity of the lubricating oil leading to inadequate lubrication and stress on, or mechanical failure of, the refrigeration apparatus. Higher oil-return agent concentrations than about 10 weight percent of the total composition have also been observed to negatively influence the capacity and performance of a refrigerant composition.

An effective amount of hydrocarbon oil-return agent in the present inventive compositions leads to halogenated hydrocarbon and oil becoming miscibilized to the extent that adequate return of oil in a compression refrigeration system from non-compressor evaporator) to compressor zones is obtained.

Hydrocarbon oil-return agent of the present inventive compositions comprises aliphatic, straight, branched, or cyclic chain hydrocarbons having at least seven carbon atoms and sixteen or less carbon atoms. For example, heptanes, octanes, nonanes, decanes, undecanes, kerosene, and mixtures thereof, and in particular refined kerosene with a sulfur content less than 0.2 weight%.

Preferred of the hydrocarbon oil-return agents are those which are classified as combustible (as opposed to flammable) by ASTM D-93. So-classified combustible hydrocarbons are preferred as oil-return agents as their use in any quantity will not result in flammability being rendered to a refrigeration composition. A preferred hydrocarbon oil-return agent has from seven to sixteen WO 00/42118 PCT/US99/15935 carbon atoms A more preferred hydrocarbon oil-return agent has from eleven to thirteen carbon atoms. A most preferred commercially available compound useful as hydrocarbon oil-return agent is Isopar@ H. Isopar® H is a high purity Cu to

C

1 2 iso-parafinic with low aromatics sold by Exxon Chemical, USA.

Compounds are typically considered flammable if the flash point is less than 37 0 C. Though flash points in the table below may be measured by slightly different methods, there is a trend of increasing flash point with carbon chain length. Chain lengths below ten carbon atoms may begin to become flammable. A nonflammable hydrocarbon oil-return-agent or carrier reduces flammability in refrigeration and air conditioning systems versus use of compounds such as propane, butane, isobutane and pentane, disclosed in the art as useful in promoting oil return. Also a larger amount of non-flammable hydrocarbon oil-return-agent than flammable hydrocarbon may be used without effecting system flammability.

Hydrocarbon Formula Flash Pt Boiling Pt Flammability Propane

CH

3

CH

2

CH

3 -104 -42 Flammable Isobutane (CH3)3CH -84 -12 Flammable Butane

CH

3

(CH

2 2

CH

3 -60 -1 Flammable Pentane

CH

3

(CH

2 3

CH

3 -40 36-38 Flammable Hexane CH3(CH 2 4

CH

3 -22 to -26 65-69 Flammable Heptane

CH

3

(CH

2

)SCH

3 -8 92-100 Flammable Octane

CH

3

(CH

2 6

CH

3 16 125-127 Flammable Nonane

CH

3

(CH

2 7

CH

3 31 151 Flammable Decane

CH

3

(CH

2 8

CH

3 46 174 Combustible Kerosene HC mixture 43-82 151-301 Combustible Isopar H CnI-C 12 57 182 Combustible Isoparaffin Undecane

CH

3

(CH

2 9

CH

3 60 196 Combustible Dodecane

CH

3

(CH

2 )ioCH 3 71 215-217 Combustible Tridecane

CH

3

(CH

2 1

CH

3 79 234 Combustible Tetradecane

CH

3

(CH

2 12

CH

3 100 252 Combustible Pentadecane

CH

3

(CH

2 13

CH

3 132 270 Combustible Hexadecane

CH

3

(CH

2 14

CH

3 135 287 Combustible Mineral oil Paraffin Oil 199 260-360 Combustible The present refrigerant compositions comprising halogenated hydrocarbon, oil, and hydrocarbon oil-return agent generally comprise 40-99 WO 00/42118 PCT/US99/15935 weight% halogenated hydrocarbon, 1-60 weight% oil, and 0.01-10 weight% hydrocarbon oil-return agent, based on the total composition weight. More preferably, such compositions comprise 50-90 weight% halogenated hydrocarbon, 10-50 weight% oil, and 0.01-5 weight% hydrocarbon oil-return-agent.

The further present compositions comprising: halogenated hydrocarbon, and hydrocarbon oil-return agent; and oil and hydrocarbon oil-return agent comprise weight ratios of components identical with those found in the present compositions comprising halogenated hydrocarbon, oil, and hydrocarbon oil-return agent. That is to say, in the present compositions, the weight ratio of halogenated hydrocarbon to oil is from about 0.6 (40/60) to about 99 and the weight ratio of oil to hydrocarbon oil-return agent is from about 0.1 (1/10) to about 6000 (60/.01).

The present invention further comprises processes for producing refrigeration comprising evaporating the present refrigeration compositions in the vicinity of a body to be cooled and processes for producing heat comprising condensing the present refrigeration compositions in the vicinity of a body to be heated.

The present invention further relates to processes for solubilizing a halogenated hydrocarbon in an oil comprising contacting the halogenated hydrocarbon with the oil in the presence of an effective amount of hydrocarbon oil-return agent which forms a solution of the halogenated hydrocarbon and the oil, wherein the halogenated hydrocarbon contains at least one carbon atom and one fluorine atom, and the oil is selected from the group consisting of mineral oils and synthetic oils.

The present invention further relates to processes for returning oil from a non-compressor zone to a compressor zone in a refrigeration system comprising: contacting the oil in the non-compressor zone with at least one halogenated hydrocarbon in the presence of an effective amount of a hydrocarbon oil-return agent and transferring the oil from the non-compressor zone to the compressor zone of the refrigeration system, wherein the halogenated hydrocarbon contains at least one carbon atom and one fluorine atom, and the oil is selected from the group consisting of mineral oils and synthetic oils.

The present invention further relates to processes for transferring an oil from a low pressure zone to a compressor zone in a refrigeration system, comprising: WO 00/42118 PCT/US99/15935 contacting the oil in the low pressure zone of the refrigeration system with at least one halogenated hydrocarbon in the presence of an effective amount of a hydrocarbon oil-return agent and transferring the oil from the low pressure zone to the compressor zone of the refrigeration system, wherein the halogenated hydrocarbon contains at least one carbon atom and one fluorine atom, and the oil is selected from the group consisting of mineral oils and synthetic oils.

EXAMPLES

In the following examples, percentages shown without a label refer to the weight percent of a given material in the total composition being discussed. The error in the oil return measurements reported is 0.5 wt%/o.

EXAMPLE 1 Oil return was tested in an oil-return apparatus as follows. Liquid refrigerant was fed from a pressurized cylinder through copper tubing to a heater where it was vaporized. The refrigerant vapor then passed through a pressure regulator and metering valve to control flow at a constant rate of 1,000-1,100 cc per minute and 1 atm pressure. The refrigerant vapor was fed to another copper tube 180 cm in length and 0.635 cm outer diameter formed into a U-shape placed in a constant temperature bath. The U-shaped tube (U-tube) began with a straight vertical section 37 cm long then bent to a horizontal section 27 cm long at the bottom of the bath. The tube then rose vertically in a zig-zag pattern with four 23 cm lengths, followed by another vertical straight section 23 cm long. The U-tube was filled with 10 grams of oil, optionally containing hydrocarbon oil-return agent, which was added to the U-tube through the 37 cm vertical tube. Vapor refrigerant passed slowly through the oil in the U-tube. Refrigerant and oil exiting the U-tube was collected in a receiver and refrigerant allowed to evaporate. Oil was then weighed to determine how much was carried out of the U-tube by the refrigerant.

Refrigerant R404A (44 wt% HFC-125, 52 wt% HFC-143a, and 4 wt% HFC-134a) was placed in the refrigerant cylinder. HAB 22 oil (HAB 22 is a branched alkylbenzene oil sold by Nippon Oil) or HAB plus hydrocarbon oilreturn-agent Isopar® H was placed in the copper U-tube, wherein total oil and oilreturn agent equaled 10 grams. The constant temperature bath was held at a temperature of -20°C. Refrigerant vapor was fed through the U-tube at a flow rate of 1,100 cubic centimeters per minute and weight of oil in the receiver measured WO 00/42118 PCT/US99/15935 at 6, 10, 20 and 30 minute time intervals. POE 22 polyol ester oil was compared as a baseline to HAB 22. Data are shown in Table 1 below.

TABLE 1 Wt% of Oil Returned Oil Composition in U-tube 6 Min 10 Min 20 Min POE 1.0 10.6 18.9 HAB 22 0 6.1 16.2 3% Isopar@ H in HAB 22 0 9.6 19.2 Results show oil return is equivalent to POE when Isopar@ H is added to hard alkylbenzene oil (HAB 22).

EXAMPLE 2 The apparatus and procedure of Example 1 was used to test refrigerant R401A (53 wt% HCFC-22, 13 wt% HFC-152a and 34 wt% HFC-124).

Suniso®3GS mineral oil with and without Isopar® H was compared to a baseline of Zerol® 150 alkyl benzene. Results are shown in Table 2.

TABLE 2 Weight of Oil Returned Oil Composition in U- 6 10 tube: Min Min Min 3GS 0 1.2 19.7 Zerol® 150 0 9.6 31.2 3% Isopar® H in 3GS 0.4 14.0 30.6 Results show addition of Isopar® H to 3GS mineral oil provides equivalent oil return to Zerol® 150 alkyl benzene.

EXAMPLE3 The apparatus and procedure of Example 1, with exceptions discussed below, was used to test refrigerant R407C (23 wt% HFC-32, 25 wt% HFC-125and 52 wt% HFC-134a). Suniso® 3GS mineral oil, with and without hydrocarbon oil WO 00/42118 PCT/US99/15935 return agent Isopar® H, was compared to POE. The constant temperature bath was held at -20°C. Results are shown in Table 3.

TABLE 3 Weight Oil Returned Oil Composition in U-tube 6 min 10 min 20 min POE 3.1 14.1 26.5 3GS 0 0 0 3% Isopar® H in 3GS 0 0 0.3 6% Isopar@ H in 3GS 0 0 6.7 Isopar@ H in 3GS 10.0 18.7 27.3 Results show addition of Isopar@ H to 3GS oil improves oil return and oil return performance of 15% Isopar@ H in 3GS is equivalent to POE.

EXAMPLE 4 The apparatus and procedure of Example 1, with exceptions discussed below, was used to test refrigerant R404A (44 wt% HFC-125, 52 wt 0 HFC-143a, and 4 wt% HFC-134a). Suniso® 3GS mineral oil, with and without hydrocarbon oil return agent Isopar® H, was compared to POE. The constant temperature bath was held at -20 0 C. Results are shown in Table 4.

TABLE 4 Weight Oil Returned Oil Composition in U-tube 6 min 10 min 20 min POE 0 6.2 18.9 12% Isopar® H in 3GS 4.2 13.3 23.3 Isopar@ H in 3GS 9.6 16.3 25.0 18% Isopar@ H in 3GS 17.1 24.3 33.8 Results show addition of Isopar@ H to 3GS oil improves oil return and oil return performance of 12, 15 and 18% Isopar® H in 3GS are improved versus POE lubricant.

EXAMPLE The kinematic viscosity in centistokes of Isopar@ H and pentane in 3GS mineral oil were compared to POE 22 oil at -15°C as shown in Table below. The test method used was ASTM method D446.

WO 00/42118 PCTIUS99/1 5935 TABLE Kinematic Viscosity, Cst At -15 0

C

POE 589.5 3GS 2936.7 3GS 6% Isopar@ H1277.3 3GS 12% Isopar® H 611.4 3GS 3% Pentane 971.6 The data show 12% Isopar® H in 3GS mineral oil approaches the viscosity of POE at -15 0 C. Addition of 3% pentane to 3GS provides less viscosity reduction.

Flammability is also increased when using pentane, while Isopar@ H is not flammable.

EXAMPLE 6 Tests were conducted to determine ifR404A (44 wt% HFC-125, 52 wt% HFC-143a, and 4 wt% HFC-134a) could be used in a Hussmann supermarket frozen food display case (Model HICA-0146-PLK), using conventional lubricant oil Suniso 3GS. The display case was outfitted with a Copeland semi-hermetic reciprocating compressor (Model KAL-016L) equipped with a sight glass in the oil sump. The frozen food case was installed in the indoor room of an environmental chamber and the condensing unit installed in the outdoor room.

The two units were connected by 5/8 inch outer diameter copper tubing in the suction line and by 1/2 inch outer diameter copper tubing in the liquid line. A 300 cc sample cylinder was installed between two valves in the liquid line. To determine oil circulation, the valves were closed to trap a refrigerant/oil sample during system operation. The sample cylinder was removed and weighed, refrigerant slowly evaporated, then cylinder reweighed to determine amount of refrigerant. Weight of oil remaining was used to calculate %oil in refrigerant or %oil circulation. Refrigerant R502 (48.8 wt% HCFC-22, 51.2 wt% CFC-115 (chloropentafluoroethane)) with 3GS oil was used as a baseline for comparison.

Capacity is intended to mean the change in enthalpy of the refrigerant in the evaporator per pound of refrigerant circulated, i.e. the heat removed by the refrigerant in the evaporator per time. Coefficient of performance (COP) is intended to mean the ratio of the capacity to compressor work. It is a measure of refrigerant energy efficiency. Results are shown in Table 6.

WO 00/42118 PCT/US99/15935 TABLE 6 Refrigerant/Oil Oil Circulation Capacity Combination (Kbtu/ COP R502/ 3GS 0.16 3.26 1.67 R404A/ 3GS* 0.12 3.31 1.70 R404A/6 Isopar H in 0.15 3.26 1.65 3GS** Oil level in sight glass dropped below view 0.3% Isopar® H based on refrigerant and oil The data show addition of 6 wt% Isopar® H provides similar COP, capacity, and oil circulation to the baseline R502/3GS system. Without Isopar® H, the oil level drops in the sight glass indicating insufficient oil return.

EXAMPLE 7 The Hussmann supermarket frozen food display case of Example 6 was used to study the concentration profile of Isopar@ H during system operation. 3GS mineral oil containing 15% Isopar@ H was charged to the oil sump and the system was charged with R407C. After 48 hours of operation, the oil located in the oil sump and the oil in the liquid line after the condenser were analyzed for Isopar® H concentration and a mass balance was calculated as shown in Table 7 below.

TABLE 7 Location Time (hrs) wt% Isopar® H Oil sump 0 15.0 Oil sump 48 2.3 Liquid line 48 3.2 Evaporator 48 The data show Isopar® H is volatile enough to be carried out of the oil sump and deposited in the evaporator. The presence of Isopar® H in the evaporator reduces oil viscosity allowing the oil in the evaporator to return to the compressor.

The reduction of Isopar® H concentration in the oil sump from 15% to 2.3% keeps oil viscosity sufficiently high in the sump to minimize impact on compressor lubrication.

Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification, they are to be interpreted as specifying the presence of the stated features, integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component or group thereof.

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Claims

1. A refrigerant composition comprising: a halogenated hydrocarbon refrigerant having 1-6 carbon atoms, at least one fluorine atom and optionally chlorine and oxygen atoms, having a normal boiling point of from -90 0 C to 80 0 C; a refrigeration oil selected from the group consisting of naphthenes, aromatics and polyalphaolefins; and a hydrocarbon oil-return agent selected from the group consisting of combustible, non-flammable hydrocarbons containing from 10 to 16 carbon atoms.

2. A refrigerant composition, comprising; a halogenated hydrocarbon refrigerant having 1-6 carbon atoms, at least one fluorine atom and optionally chlorine and oxygen atoms, having a normal boiling point of from -90 0 C to 80 0 C; and a hydrocarbon oil-return agent selected from the group consisting of combustible, non-flammable hydrocarbons containing from 10 to 16 carbon atoms.

3. A lubricant composition for use with a halogenated hydrocarbon refrigerant S" 20 having 1-6 carbon atoms, at least one fluorine atom and optionally chlorine and oxygen atoms, having a normal boiling point of from -90 0 C to 80 0 C, comprising: a refrigeration oil selected from the group consisting of naphthenes, aromatics and polyalphaoleflns; and a hydrocarbon oil-return agent consisting of combustible, non-flammable isoparaffins having 11 to 12 carbon atoms.

4. The composition of claim 1 wherein said hydrocarbon oil-return agent forms a solution of said refrigerant with said refrigeration oil. 30

5. The composition of claim 1 wherein said hydrocarbon oil-return agent comprises less than about 10 weight percent of said refrigerant composition.

6. The composition of claim 1 comprising from about 40 to about 99 weight percent refrigerant, from about 1 to about 60 weight percent refrigerant oil, and from about 19/02/04,atl 2120.specipgs, 14 0.01 to about 10 weight percent hydrocarbon oil-return agent.

7. The composition of claims 1 or 2 wherein said hydrocarbon oil-return agent comprises aliphatic hydrocarbons containing from 11 to 13 carbon atoms.

8. A process for producing refrigeration comprising evaporating a composition of claims 1 or 2 in the vicinity of a body to be cooled.

9. A process for producing heat comprising condensing a composition of claims 1 or 2 in the vicinity of a body to be heated.

A process for returning oil from a non-compressor zone to a compressor zone in a compression refrigeration system comprising: contacting a refrigeration oil, selected from the group consisting of naphthenes, aromatics and polyalphaolefins, in the non-compressor zone with halogenated hydrocarbon refrigerant having 1-6 carbon atoms, at least one fluorine atom and optionally chlorine and oxygen atoms, having a normal boiling point of from -90 0 C to 80 0 C, in the presence of a hydrocarbon oil-return agent selected from the group consisting of combustible, non-flammable aliphatic hydrocarbons containing from 10 to 16 carbon 20 atoms, to form a solution comprising oil, refrigerant, and hydrocarbon oil return agent; and transferring the solution from the non-compressor zone to the compressor zone of the refrigeration system.

11. The process of claim 10 wherein the hydrocarbon oil-return agent comprises less than 10 weight percent of the solution comprising refrigerant, refrigeration oil, and hydrocarbon oil-return agent. 0*

12. The process of claim 10 wherein the solution comprising refrigerant, refrigeration oil, and hydrocarbon oil-return agent comprises from 40 to 99 weight percent 30 refrigerant, from 1 to 60 weight percent refrigeration oil, and from 0.01 to 10 weight percent hydrocarbon oil-return agent.

13. The process of claim 10, wherein said hydrocarbon oil return agent is selected from aliphatic hydrocarbons containing from 11 to 13 carbon atoms. 18/02/04.at 12120. specipgs,

14. A refrigerant composition as defined in claim 1 and substantially as hereinbefore described with reference to any one of the examples.

15. A process as defined in claim 10 and substantially as hereinbefore described with reference to any one of the examples. DATED this 18 th day of February, 2004 E.I. DU PONT DE NEMOURS AND COMPANY By their Patent Attorneys: CALLINAN LAWRIE 0 18/02/04.at 12120.specipgs, 16