EP2125986A1

EP2125986A1 - Refrigerant composition

Info

Publication number: EP2125986A1
Application number: EP08718751A
Authority: EP
Inventors: John Edward Poole; Richard Powell
Original assignee: RPL Holdings Ltd
Current assignee: RPL Holdings Ltd
Priority date: 2007-03-19
Filing date: 2008-03-14
Publication date: 2009-12-02
Also published as: GB2447629A; WO2008113984A1; CA2681272A1; GB0705219D0

Abstract

A refrigerant composition consists essentially of three hydrofluorocarbon components selected from HFC134a, HFC125 and HFC143a which replaces HCFC22 in new equipment.

Description

REFRIGERANT COMPOSITION

This invention relates to refrigerant compositions, particularly to refrigerant compositions which have minimal adverse effect on stratospheric ozone. The invention particularly relates to compositions which are for use in new and existing refrigeration, air conditioning and heat pumping equipment. These refrigerant compositions are compatible with the new synthetic lubricants, including but not restricted to polyol ester oils and polyalkylene glycol oils.

It is well known that chlorofluorocarbons (CFCs) such as CFC12 and CFC502 and hydrochlorofluorocarbons such as HCFC22 while being energy efficient, non flammable and of low toxicity, migrate to the stratosphere where they are broken down by ultra violet light to attack the ozone layer. It is desirable to replace these Ozone Depleting Substances (ODS) by non ozone depleting alternatives such as hydro fluorocarbons (HFCs) which are also non flammable, efficient and of low toxicity. There are six main HFCs, namely HFC134a, HFC32, HFC125, HFC143a, HFC227ea and HFC 152a, which either individually or when blended into mixtures can replace CFCs and HCFCs. While HFC 134a, HFC227ea and HFC 152a can be used to replace ODS directly, HFC32, HFC143a and HFC125 are generally found in blends as replacements for ODS. HFCs do not have adequate solubility in traditional lubricants such as mineral and alkylbenzene oils so that synthetic oxygen containing lubricants have been introduced specifically in order that HFCs can be used in new equipment.

Refrigerant blends such as R404A, R507A and others have been commercialised as replacements for CFCs and HCFCs at low temperature, typically operating at around -35⁰C in the evaporator but their performance declines as the temperature rises so that they are not effective, for example, as replacements for ODS in air conditioning applications. R404A and R507A have been formulated primarily to replace CFC502 at low temperatures,

Refrigerant blends such as R407C, R410A and others have been commercialised as replacements for CFCs and HCFCs at medium to high temperatures, typically operating at around +5⁰C in the evaporator and condensing at around +35⁰C but their performance declines as the temperature decreases so that they are not effective, for example, as replacements for ODS in refrigeration applications such as are used in supermarkets. R407C and R410A have been formulated primarily to replace HCFC22 for air conditioning applications. R407C is a zeotrope, not an azeotrope or near azeotrope, so its application is further restricted by having a comparatively high temperature glide in the evaporator which can cause icing at the entry of the evaporator thus reducing the energy efficiency and the capacity of the system. Furthermore, R407C, being a zeotrope, is unacceptable for flooded systems where large composition shifts would occur resulting in large compression ratios and potential over-pressurisation of the condenser.

An object of this invention is to provide a refrigerant blend that can be readily used to replace R22 in new & existing equipment. It is especially important that such a blend should have an adequate refrigeration capacity. The capacity should be at least 90% of that of the fluid it is replacing, more preferably at least 95% of that of the fluid it is replacing and most preferably equal to or greater than that of the fluid it is replacing under similar operating conditions. It is an object of this invention to provide refrigerant compositions which have capacities similar to R22 across the range of applications for air conditioning & refrigeration from high to low temperatures where R22 is commonly found.

There is no HFC refrigerant blend which has been commercialised which has a safety classification of Al according to ASHRAE Standard 34, being of low toxicity and non flammable, which can match the capacity, performance and pressures of HFCF22 across the range of applications where HCFC22 is found including refrigeration and air conditioning applications including centrifugal chillers. An object of this invention is to provide refrigerant compositions with low temperature glides of less than 2⁰C that match the thermodynamic performance of HCFC22 across the temperature range of applications where HCFC22 is commonly found including refrigeration and air conditioning applications operating at evaporator temperatures ranging from +5⁰C to -40⁰C. It is known in the art that high compression ratios can result in increased energy usage and the potential for compressor damage. This invention relates to refrigerant compositions which have compression ratios which should be at least no more than 10% of that of the fluid it is replacing, more preferably no more than 5% of that of the fluid it is replacing and most preferably equal to or lower than that of the fluid it is replacing under similar operating conditions. Preferred aspects of this invention relate to refrigerant compositions which have compression ratios which are similar to R22 across the range of applications for air conditioning & refrigeration from high to low temperatures where R22 is commonly found.

Various terms have been used in patent literature to describe refrigerant mixtures. The following definitions are taken from Standard 34 of the American Society of Heating, Refrigerating & Air Conditioning Engineers (ASHRAE);

Azeotrope: an azeotropic blend is one containing two or more refrigerants whose equilibrium vapour and liquid phase compositions are the same at a given pressure. Azeotropic blends exhibit some segregation of components at other conditions. The extent of the segregation depends on the particular azeotrope and the application.

Azeotropic temperature: the temperature at which the liquid and vapour phases of a blend have the same mole fractionation of each component at equilibrium for a specified pressure.

Near azeotrope: a zeotropic blend with a temperature glide sufficiently small that it may be disregarded without consequential error in analysis for a specific application.

Zeotrope: blends comprising multiple components of different volatilities that, when used in refrigeration cycles, change volumetric composition and saturation temperatures as they evaporate (boil) or condense at constant pressure.

Temperature glide: the absolute value of the difference between the starting and ending temperatures of a phase-change process by a refrigerant within a component of a refrigerating system, exclusive of any subcooling or superheating. This term usually describes condensation or evaporation of a zeotrope.

According to the present invention, a refrigerant composition consists of: a refrigerant composition suitable for air conditioning, refrigeration and heat pumping applications consisting essentially of: Rl 34a 10 to 20%

Rl 25 40 to 65%

R143a 50 to 15% wherein the percentages above are selected to total 100%. A preferred composition consists essentially of:

Rl 34a 10 to 20%

R125 40 to 60%

Rl 43a 50 to 20%.

A further preferred composition consists essentially of: Rl 34a 10 to 20%

R125 40 to 55%

Rl 43a 50 to 25%.

A further preferred composition consists essentially of:

Rl 34a 10 to 20%

Rl25 40 to 50% R143a 50 to 30%

A further preferred composition consists essentially of: Rl 34a 10 to 20%

Rl25 40 to 45% R143a 50 to 35%

A further preferred composition consists essentially of: Rl 34a 15 to 20%

Rl 25 40 to 65%

R143a 45 to 15% A further preferred composition consists essentially of:

Rl 34a 15 to 20%

Rl 25 40 to 60% R143a 45 to 20%

A further preferred composition consists essentially of:

Rl 34a 15 to 20%

R125 40 to 55% Rl 43a 45 to 25%

A further preferred composition consists essentially of: Rl 34a 15 to 20%

Rl 25 40 to 50%

R143a 45 to 30% An especially preferred composition consists essentially of:

Rl 34a 15%

Rl 25 65%

Rl 43a 20%

A further especially preferred composition consists essentially of:

Rl 34a 15%

R125 60%

R143a 25%

A further especially preferred composition consists essentially of:

Rl 34a 15%

Rl 25 55%

R143a 30%

A further especially preferred composition consists essentially of:

Rl 34a 15%

Rl 25 50% Rl 43a 35% A further especially preferred composition consists essentially of:

Rl 34a 15%

Rl 25 45%

Rl 43a 40% A further especially preferred composition consists essentially of:

Rl 34a 20%

Rl 25 65%

R143a 15%

A further especially preferred composition consists essentially of:

Rl 34a 20%

Rl 25 60%

R143a 20%

A further especially preferred composition consists essentially of:

Rl 34a 20%

Rl 25 55%

R143a 25%

A further especially preferred composition consists essentially of:

Rl 34a 20%

Rl 25 50% Rl 43a 30%

A further especially preferred composition consists essentially of:

Rl 34a 20%

Rl 25 45%

R143a 35% A further especially preferred composition consists essentially of:

Rl 34a 20%

Rl 25 40%

R143a 40%

A further especially preferred composition consists essentially of:

Rl 34a 16%

Rl 25 42%

Rl 43a 42%

A further especially preferred composition consists essentially of:

Rl 34a 17%

Rl 25 42%

R143a 41%

A further especially preferred composition consists essentially of:

Rl 34a 19%

R125 41%

Rl 43a 41%

A further especially preferred composition consists essentially of:

Rl 34a 18%

Rl 25 41% R143a 40%

The compositions of this invention consist of the components mentioned above, optionally with small amounts of impurities or additives in an amount which is not sufficient to affect the essential properties of the composition. Preferably no additives are used. Preferred compositions meet the criteria for safety classifications Al and A2 of ASHRAE Standard 34 or meet the criteria for safety classification Al of ASHRAE Standard 34

The compositions may be used in an air conditioning unit with a synthetic oxygen- containing lubricant or may be used in a refrigeration unit with a synthetic oxygen containing lubricant.

The lubricant may be a polyol ester, a polyether or a mixture of oxygen- containing lubricants.

The compositions may be used in a hermetic or semi-hermetic refrigeration unit providing cold temperatures in a range between about 0 ⁰C and about -45 ⁰C, or may be used in an open refrigeration unit driven by an external power source providing cold temperatures in a range between about 0 ⁰C and about -45 ⁰C. The compositionsr may be used in an hermetic or semi-hermetic air conditioning unit providing cold temperatures in a range between about 0 ⁰C and about 20 ⁰C, or may be used in an hermetic or semi-hermetic heat pump unit providing warm temperatures in a range between about 15 ⁰C and about 50 ⁰C.

The composition may also be used in an open air conditioning unit driven by an external power source providing cold temperatures in a range between about 0 ⁰C and about 20 ⁰C.

The composition may be used in an open heat pump unit driven by an external power source providing warm temperatures in a range between about 15 ⁰C and about 50 ⁰C.

These compositions preferably meet the criteria for safety classification A2 of ASHRAE Standard 34 and more preferably meet the stricter Al classification.

Preferred compositions comprise near azeotropic and zeotropic refrigerant compositions, which are non flammable under all conditions of fractionation as defined under ASHRAE Standard 34, and which can be used to replace HCFC22 in new & existing equipment across the application ranges including refrigeration and air conditioning and centrifugal chillers. These refrigerant applications are compatible with the oxygen containing synthetic lubricants including but not restricted to polyol ester, polalkylbenzene & polether oils.

Not all HFCs are non flammable as defined under ASHRAE Standard 34. HFC 143a and HFC32 have not received a non flammable rating by ASHRAE. Preferred embodiments of this invention relate to compositions of refrigerants which cover blends of non flammable HFCs with flammable HFCs selected so that all such compositions are non flammable during fractionation while providing similar refrigerating effects and thermodynamic performances to HCFC22.

To avoid flammability in the blend, or in a fraction generated by a leak, for example as defined by ASHRAE Standard 34, the ratio of flammable HFC to non flammable HFC should be minimised but without adversely affecting the thermodynamic performance of the composition. One of the HFC components of this invention, namely HFC 143a, has an ASHRAE safety classification of A2 which makes limitation of the amount of HFC 143a used relative to the amounts of non- flammable components important to obtaining a non flammable rating of Al for the blend.

Preferred compositions in accordance with this invention may not contain any hydrocarbon compound.

Preferred compositions provide very similar performance to HCFC22 across the evaporating temperature range commonly associated with HCFC22.

Percentages and other proportions referred to in this specification are by weight unless indicated otherwise and are selected to total 100% from within the ranges disclosed.

The invention is further described by means of examples but not in a limitative sense. Example 1

Blends of R125, R143a and R134a were evaluated in a typical hermetic or semi- hermetic air conditioner using NIST's CYCLE D program. COOLING DUTY DELIVERED 10 kW EVAPORATOR

Midpoint evaporating temperature 7 ° C

Superheating 5.0 ⁰C

Suction line pressure drop (in saturated temperature) 1.5 ⁰C

CONDENSER Midpoint fluid condensing temperature 45.ⁱ O ⁰C

Subcooling 5.0 ⁰C

Discharge line pressure drop (in saturated temperature) 1.5 ⁰C LIQUID LINE/SUCTION LINE HEAT EXCHANGER Efficiency 0.3 COMPRESSOR

Compressor isentropic efficiency 0.7

Compressor volumetric efficiency 0.82

Motor efficiency 0.85

PARASITIC POWER Evaporator fan 0.3 kW

Condenser fan 0.4 kW

Controls 0.1 kW

The results of analysing the performances in an air conditioning unit using these operating parameters are shown in Table 1 , plus R22 for comparison.

Table 1 Air conditioning

Example 2

Blends of R125, R143a and R134a were evaluated in a typical open compressor refrigeration unit using NIST's CYCLE D program. COOLING DUTY DELIVERED 10 kW

EVAPORATOR

Midpoint evaporating temperature -35 ⁰C

Superheating 5.0 ⁰C

Suction line pressure drop (in saturated temperature) 1.5 ⁰C CONDENSER

Midpoint fluid condensing temperature 35.0 ⁰C

Subcooling 5.0 ⁰C

Discharge- line pressure drop (in saturated temperature) 1.5 ⁰C LIQUID LINE/SUCTION LINE HEAT EXCHANGER Efficiency 0.3

COMPRESSOR

Compressor isentropic efficiency 0.7

Compressor volumetric efficiency 0.82

Motor efficiency 0.85 PARASITIC POWER

Evaporator fan 0.3 kW

Condenser fan 0.4 kW

Controls 0.1 kW

The results of analysing the performances in a refrigerator unit using these operating parameters are shown in Table 2, plus R22 for comparison.

Table 2 Refrigeration

W

Claims

1. A refrigerant composition consisting essentially of: Rl 34a 10 to 20%

Rl 25 40 to 65% R143a 50 to 15% wherein the percentages of the ingredients are selected to total 100% by weight.

2. A refrigerant composition as claimed in claim 1 consisting essentially of: R134a 10 to 20%

R125 40 to 60%

R143a 50 to 20%

3. A refrigerant composition as claimed in claim 2 consisting essentially of: Rl 34a 10 to 20%

R125 40 to 55% Rl 43a 50 to 25%

4. A refrigerant composition as claimed in claim 3 consisting essentially of:

Rl 34a 10 to 20%

Rl 25 40 to 50%

R143a 50 to 30%

5. A refrigerant composition as claimed in claim 4 consisting essentially of:

Rl 34a 10 to 20%

R125 40 to 45%

R143a 50 to 35%

6. A refrigerant composition as claimed in claim 1 consisting essentially of:

R 134a 15 to 20%

R 125 40 to 65%

R143a 45 to 15%

7. A refrigerant composition as claimed in claim 6 consisting essentially of:

Rl 34a 15 to 20%

Rl 25 40 to 60% Rl 43a 45 to 20%

8. A refrigerant composition as claimed in claim 7 consisting essentially of:

Rl 34a 15 to 20%

Rl 25 40 to 55% .

Rl 43a 45 to 25%

9. A refrigerant composition as claimed in claim 8 consisting essentially of:

Rl 34a 15 to 20%

Rl 25 40 to 50%

R143a 45 to 30%

10. A refrigerant composition as claimed in claim 1 consisting essentially of:

R134a 15%

R125 65%

R143a 20%

11. A refrigerant composition as claimed in claim 2 consisting essentially of:

Rl 34a 15%

R125 60%

Rl 43a 25%

12. A refrigerant composition as claimed in claim 4 consisting essentially of:

Rl 34a 15%

R 125 55% R143a 30%

13. A refrigerant composition as claimed in claim 4 consisting essentially of:

Rl 34a 15%

Rl 25 50% R143a 35%

14. A refrigerant composition as claimed in claim 4 consisting essentially of:

R134a 15%

R125 45%

R143a 40%

15. A refrigerant composition as claimed in claim 1 consisting essentially of:

Rl 34a 20%

Rl 25 65%

R143a 15%

16. A refrigerant composition as claimed in claim 2 consisting essentially of: -

R134a 20%

Rl 25 60%

R143a 20%

17. A refrigerant composition as claimed in claim 3 consisting essentially of:

Rl 34a 20%

R125 55%

R143a 25%

18. A refrigerant composition as claimed in claim 9 consisting essentially of:

Rl 34a 20%

R125 50% R143a 30%

19. A refrigerant composition as claimed in claim 9 consisting essentially of:

Rl 34a 20%

R125 45% R143a 35%

20. A refrigerant composition as claimed in claims 9 consisting essentially of:

R134a 20%

R125 40%

R143a 40%

21. A refrigerant composition as claimed in claims 9 consisting essentially of:

R134a 16%

R125 42% ^*

Rl 43a 42%

22. A refrigerant composition as claimed in claims 9 consisting essentially of:

R134a 17%

R125 42%

Rl 43a 41%

23. A refrigerant composition as claimed in claims 9 consisting essentially of:

Rl 34a 19%

R125 41%

R143a 41%

24. A refrigerant composition as claimed in claims 9 consisting essentially of:

Rl 34a 18%

R125 41% R143a 40%

25. A refrigerant composition as claimed in any of claims 1-24 which meet the criteria for safety classifications Al and A2 of ASHRAE Standard 34

26. A refrigerant composition as claimed in any of claims 1-24 which meet the, criteria for safety classification Al of ASHRAE Standard 34

27. A refrigerantas claimed in any of claims 1 to 26 used in an air conditioning unit with a synthetic oxygen- containing lubricant.

28. A refrigerant composition as claimed in any of claims 1 to 26 used in a refrigeration unit with a synthetic oxygen containing lubricant.

29. A refrigerant composition as claimed in claims 27 and 28 in which the lubricant is a polyol ester.

30. A refrigerant composition as claimed in claim 27 or 28 in which the lubricant is a polyether.

31. A refrigerant composition as claimed in any of claims 1 to 26 used in an air conditioning unit in which the lubricant is a mixture of oxygen-containing lubricants.

32. A refrigerant composition as claimed in any of claims 1 to 26 used in a refrigeration unit in which the lubricant is a mixture of oxygen-containing lubricants.

33. A refrigerant composition as claimed in any of claims 1 to 32 used in an hermetic or semi-hermetic refrigeration unit providing cold temperatures in a range between about 0 ⁰C and about -45 ⁰C.

34. A refrigerant composition as claimed in any of claims 1 to 32 used in an open refrigeration unit driven by an external power source providing cold temperatures in a range between about 0⁰C and about -45 ⁰C.

35. A refrigerant composition as' claimed in any of claims 1 to 32 used in an hermetic or semi-hermetic air conditioning unit providing cold temperatures in a range between about 0 ⁰C inH about 20⁰C.

36. A refrigerant composition as claimed in any of claims 1 to 32 used in an open air conditioning unit driven by an external power source providing cold temperatures in a range between about 0 ⁰C and about 20 ⁰C.

37. A refrigerant composition as claimed in any of claims 1 to 32 used in an hermetic or semi-hermetic heat pump unit providing warm temperatures in a range between about 15 ⁰C and about 50 ⁰C.

38. A refrigerant composition as claimed in any of claims 1 to 32 used in an open heat pump unit driven by an external power source providing warm temperatures in a range between about 15 ⁰C and about 50 ⁰C.

39. A refrigerant composition as claimed in any preceding claim, the composition not including a hydrocarbon component.