AU668120B2 - Compositions useful as refrigerants - Google Patents

Description

OPI DATE 03/08/93 APPLN. ID AOJP LATE 14/10/93 PCT NUMBER 31689/93 PCT/GB92/02384 I llllllll lllli IilI ll III AU9331689 INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 5 (11) International Publication Number: WO 93/14175 C09K 5/04 Al 9K 5/04 (43) International Publication Date: 22 July 1993 (22.07.93) (21) International Application Number: PCT/GB92/02384 (74)Agents: DEE, Ian, Mark et al.; ICI Group Patents Services Dept, P.O. Box 6, Shire Park, Bessemer Road, Wel- (22) International Filing Date: 23 December 1992 (23.12.92) wyn Garden City, Hertfordshire AL7 IHD (GB).

Priority data: (81) Designated States: AU, BR, CA, JP, KR, US, European 9200481.1 10 January 1992 (10.01.92) GB patent (AT, BE, CH, DE, DK, ES, FR, GB, GR, IE, IT, 9200522.2 10 January 1992 (10.01.92) GB LU, MC, NL, PT, SE).

(71) Applicant (for all designated States except US): IMPERIAL Published CHEMICAL INDUSTRIES PLC [GB/GB]; Imperial With internationalsearch report.

Chemical House, Millbank, London SWIP 3JF (GB).

(72) Inventors; and Inventors/Applicants (for US only) POWELL, Richard, LLewellyn [GB/GB]; 9 Sadler's Wells, Bunbury, Tarporley, Cheshire CW6 9NV MORRISON, James, David [GB/GB]; 12 Niddries Lane, Moulton, Northwich, Cheshire CW9 8QE (GB).

(54)Title: COMPOSITIONS USEFUL AS REFRIGERANTS (57) Abstract A refrigerant composition comprising a mixture of difluoromethyl trifluoromethyl ether and at least one other fluorine containing compound selected from 1,1,1,2-tetrafluoroethane, fluoromethyl trifluoromethyl ether and bis(difluoromethyl) ether is claimed.

L -1 i I- WO 93/14175 PCT/G B92/02384 COMPOSITIONS USEFUL AS REFRIGERANTS.

The present invention relates generally to refrigerant compositions for cooling and heating applications and to the use of such compositions in heat transfer devices. More particularly, the present invention is concerned with refrigerant compositions which are designed to replace dichlorodifluoromethane (Refrigerant R-12) and the azeotropic mixture of dichlorodifluoromethane with 1,1-difluoroethane (Refrigerant R-152a), the azeotrope being Refrigerant R-500.

Mechanical refrigeration systems and related heat transfer devices such as heat pumps and air-conditioning systems are well known. In such devices, a refrigerant liquid of a suitable boiling point evaporates at low pressure taking heat from a surrounding zone. The resulting vapour is then compressed and passed to a condenser where it condenses and gives off heat to a second zone, the condensate being returned through an expansion valve to the evaporator, so completing the cycle. The mechanical energy required for compressing the vapour and pumping the liquid may be provided by an electric motor or an internal combustion engine.

I In addition to having a suitable boiling point and a high latent heat of vaporisation, the properties i preferred of a refrigerant include low toxicity, noni flammability, non-corrosivity, high stability and freedom from objectionable odour.

Hitherto, heat transfer devices have tended to use fully and partially halogenated chlorofluorocarbon refrigerants such as dichlorodifluoromethane (Refrigerant R-12) and chlorodifluoromethane (Refrigerant R-22).

WO 93/14175 PCT/GB92/02384 2 In recent years, however, there has been increasing international concern that the fully and partially halogenated chlorofluorocarbons may be damaging the earth's protective ozone layer and there is general agreement that their manufacture and use should be severely restricted and eventually phased out completely.

Whilst heat transfer devices of the type to which the present invention relates are essentially closed systems, loss of refrigerant to the atmosphere can occur due to leakage during operation of the equipment or during maintenance procedures. It is important, therefore, to replace fully and partially halogenated chlorofluorocarbon refrigerants by materials having substantially lower, preferably zero, ozone depletion potentials.

In addition to the possibility of ozone depletion, it has been suggested that significant concentrations of chlorofluorocarbon refrigerants in the atmosphere might contribute to global warming (the so-called greenhouse effect). It is desirable, therefore, to use refrigerants which have relatively short atmospheric lifetimes as a result of their ability to react with other atmospheric constituents such as hydroxyl radicals.

The present invention provides a refrigerant composition which may be used in place of Refrigerants R-12 and R-500, particularly the former. The composition contains refrigerant compounds which have essentially zero ozone depletion potentials and comparatively low direct global warming potentials.

Accordingly, the present invention provides a refrigerant composition comprising a mixture of difluoromethyl trifluoromethyl ether (CF30CHF 2 and at i! c. I WO 93/14175 PCT/GB92/02384 3 least one other fluorine containing compound selected from 1,1,1,2-tetrafluoroethane

(CF

3

CH

2 fluoromethyl trifluoromethyl ether (CF 3 0CH 2 F) and bis(difluoromethyl) ether (CHF 2

OCHF

2 Refrigerant compositions in accordance with the present invention typicaliv contain from 5 to 95Z by weight of difluoromethyl rifluoromethyl ether and from 95 to 5Z by weight of at least one compound selected from 1,1,1,2-tetrafluoroethane, fluoromethyl trifluoromethyl ether and bis(difluoromethyl) ether.

Additionally, the refrigerant compositions of the invention may contain other refrigerant compounds which have low and preferably zero ozone depletion potentials, for example other hydrofluoroalkanes and/or other fluorinated ethers containing residual hydrogen atoms. Examples of other hydrofluoroalkanes which may be incorporated in the refrigerant compositions of the invention include difluoromethane (R-32), 1,1,1-trifluoroethane (R-143a), 1,1,2,2-tetrafluoroethane (R-134), pentafluoroethane (R-125) and 1,1-difluoroethane (R-152a). Examples of other fluorinated ethers which may be included in the refrigerant compositions of the invention are the fluorinated dimethyl ethers containing residual hydrogen atoms.

Although the refrigerant compositions of the invention may comprise other refrigerant compounds, the preferred refrigerant compositions of the invention 3O consist essentially of difluoromethyl trifluoromethyl ether and at least one other fluorine containing compound selected from 1,1,1,2-tetrafluoroethane, fluoromethyl trifluoromethyl ether and bis(difluoromethyl) ether.

IL WO 93/14175 PCT/GB92/02384 4 Although the refrigerant compositions of the invention may be zeotropic they are preferably azeotropic or azeotrope-like.

The preferred compounds for use in admixture with the difluoromethyl trifluoromethyl ether are 1,1,1,2-tetrafluoroethane and fluoromethyl trifluoromethyl ether, since the resulting refrigerant compositions may provide a particularly suitable replacement for Refrigerant R-12.

Therefore, according to one preferred embodiment i of the present invention there is provided a refrigerant composition comprising a mixture of ii difluoromethyl trifluoromethyl ether and 1,1,1,2-tetrafluoroethane. Such compositions may additionally comprise one or more further refrigerant compounds, such as fluoromethyl trifluoromethyl ether i and/or bis(difluoromethyl) ether and/or at least one other fluorinated ether containing residual hydrogen Satoms and/or at least one other hydrofluoroalkane.

Hjowever, refrigerant compositions which consist essentially of difluoromethyl trifluoromethyl ether and 1,1,1,2-tetrafluoroethane are preferred.

In the case of refrigerant compositions comprising difluoromethyl trifluoromethyl ether and 1,1,1,2-tetrafluoroethane as essential components, compositions comprising from 25 to 75 Z by weight of difluoromethyl trifluoromethyl ether and from 75 to Z by weight of 1,1,1,2-tetrafluoroethane are preferred, with compositions comprising from 25 to 50 Z by weight of difluoromethyl trifluoromethyl ether and from 75 to 50 Z by weight of 1,1,1,2-tetrafluoroethane being especially preferred.

Table 1 shows the results of analysing the performance of a number of refrigerant compositions of

L

WO 93/14175 PC/GB92/02384 5 the invention in a refrigeration cycle to assess the suitability thereof as a replacement for R-12. All the compositions analysed comprised difluoromethyl trifluoromethyl ether (E-125 in the Table) and 1,1,1,2-tetrafluoroethane (R-134a in the Table) in varying amounts. The percentage by weight of each component in the refrigerant compositions analysed is given in the second row of the Table. Thus, the results of analysing the performance of the following refrigerant compositions are given in Table 1: A composition comprising 75 Z by weight of 1,1,1,2-tetrafluoroethane and 25 Z by weight of difluoromethyl trifluoromethyl ether.

A composition comprising 50 Z by weight of 1,1,1,2-tetrafluoroethane and 50 Z by weight of difluoromethyl trifluoromethyl ether.

A composition comprising 25 Z by weight of 1,1,1,2-tetrafluoroethane and 75 Z by weight of difluoromethyl trifluoromethyl ether.

The operating conditions which were used for the analysis are comparable to those existing in a domestic refrigeration system. Specifically, these conditions were as follows: Evaporator Temperature: -25 0

C

Condenser Temperature: 40 0

C

Superheat: Subcooling: 10 0

C

Cooling Duty: 1 KW Isentropic Compressor Efficiency: 75 Z I r WO 93/14175 PCT/GB92/02384 6 The performance parameters of the refrigerant compositions which are presented in Table 1, i.e.

condenser pressure, evaporator pressure, discharge temperature, return gas temperature, volumetric flow, system efficiency (coefficient of performance, by which is meant the ratio of cooling duty achieved to mechanical energy supplied to the compressor), refrigeration capacity (cooling duty per unit swept volume of the compressor), and the glide in the evaporator (the temperature range over which the refrigerant composition boils in the evaporator), are all art recognised parameters.

The performance of Refrigerant R-12 under identical operating conditions is also shown in Table 1 by way of comparison.

From Table 1, it is apparent that refrigerant compositions according to the invention comprising difluoromethyl trifluoromethyl ether and 1,1,1,2-tetrafluoroethane can exhibit a performance in a refrigeration system which is comparable to that of Refrigerant R-12. It is also apparent that refrigerant compositions containing from 25 to 50 Z by weight of difluoromethyl trifluoromethyl ether and from 75 to 50 Z by weight of 1,1,1,2-tetrafluoroethane offer a particularly suitable alternative to Refrigerant R-12.

Furthermore, the glide in the evaporator for all the Smixed refrigerant compositions tested was 0.8 0 C or less showing that such compositions are azeotrope like.

S 30 According to another preferred embodiment of the present invention there is provided a refrigerant composition comprising a mixture of difluoromethyl trifluoromethyl ether and fluoromethyl trifluoromethyl ether. Such compositions may additionally comprise one or more further refrigerant compounds, such as i.

~II~_

WO 93/14175 PCT/GB92/02384 7- 1,1,1,2-tetrafluoroethane and/or bis(difluoromethyl) ether and/or at least one other fluorinated ether containing residual hydrogen atoms and/or at least one other hydrofluoroalkane. However, refrigerant compositions which consist essentially of difluoromethyl trifluoromethyl ether and fluoromethyl trifluoromethyl ether are preferred.

Compositions comprising difluoromethyl trifluoromethyl ether and fluoromethyl trifluoromethyl ether benefit from the high capacity (cooling duty per unit swept volume) of the former compound and high efficiency (coefficient of performance) of the latter compound. Such compositions preferably comprise from to 75 Z by weight of difluoromethyl trifluoromethyl ether and from 75 to 25 Z by weight of fluoromethyl trifluoromethyl ether.

Table 2 shows the results of analysing the 0 performance of a number of refrigerant compositions of the invention in a refrigeration cycle to assess the suitability thereof as a replacement for R-12. All the compositions analysed comprised difluoromethyl trifluoromethyl ether (E-125 in the Table) and fluoromethyl trifliromethyl ether (E-134a in the Table) in varying amounts. The percentage by weight of each component in the refrigerant compositions analysed is given in the second row of the Table. Thus, the results of analysing the performance of the following refrigerant compositions are given in Table 2: A composition comprising 75 Z by weight of difluoromethyl trifluoromethyl ether and 25 Z by weight of fluoromethyl trifluoromethyl ether.

i ii-IIICllpllt^ir~iiP1 WO 93/14175 PCT/GB92/02384 8 A composition comprising 50 Z by weight of difluoromethyl trifluoromethyl ether and 50 Z by weight of fluoromethyl trifluoromethyl ether.

A composition comprising 25 Z by weight of difluoromethyl trifluoromethyl ether and 75 Z by weight of fluoromethyl trifluoromethyl ether.

The operating conditions which were used for the analysis are comparable to those existing in a domestic refrigeration system. Specifically, these conditions were as follows: Evaporator Temperature: -25 0

C

Condenser Temperature: 40 0

C

Superheat: 45 0

C

Subcooling: 10 0

C

Cooling Duty: 1 KW Isentropic Compressor Efficiency: 75 Z The performance parameters of the refrigerant compositions which appear in Table 2 have been described previously in connection with Table 1.

The performance of Refrigerant R-12 under identical operating conditions is also shown in Table 2 by way of comparison.

From Table 2, it is apparent that refrigerant compositions according to the invention comprising difluoromethyl trifluoromethyl ether and fluoromethyl trifluoromethyl ether can exhibit a performance in a refrigeration system which is not too far removed from that of Refrigerant R-12. Furthermore, the glide in the evaporator for all the mixed refrigerant compositions tested was 1.9 0 C or less showing that such compositions are azeotrope like.

(i WO 93/14175 PCT/GB92/02384 9 The refrigerant compositions of the invention may be prepared by a simple mixing process.

The compositions are useful in all types of compression cycle heat transfer devices. Thus, they may be used to provide cooling by a method involving condensing the refrigerant composition and thereafter evaporating it in a heat exchange relationship with a.

body to be cooled. They may also be used to provide i0 ji heating by a method involving condensing the refrigerant composition in a heat exchange relationship with a body to be heated and thereafter evaporating it.

The compositions of the invention provide a good Scompromise between atmospheric lifetime, ozone depletion potential and efficiency. They are especially Svaluable for applications currently satisfied by R-12 isuch as domestic refrigeration.

I I L WO 93/14175 WO 9314175PCT/GB92/02384 10 TABLE 1

REFRIGERANT

Z BY WEIGHT R-12 R-134a/E-125 100 75/25 50/50 25/75

CONDENSER

PRESSURE (Bar) ZVAP ORATOR PRESSURE (Bar)

DISCHARGE

TEMPERATURE 0

C)

RETURN GAS TEMPERATURE (OC)

VOLUMETRIC

FLOW (M 3 /s x 10i) COOLING DUTY PER UNIT SWEPT VOLUME (KW/m-) COEFFICIENT OF

PERFORMANCE

BOILING BP* POINT (OC) DP** GLIDE IN EVAPORATOR 0

C)

9.60 10.87 11.56 12.29 1.23 1.21 1.36 99.5 120.8 106.0 1.54 93.8 20 .3 20.0 20 .3 20 .3 0.140 0.145 0.138 0.133 714 1.90 -29 .8 -29.8 0 690 1.82 -30 .11 -28.92 0.6 725 1'.7 6 -33.21 -31.66 0.8 752 1.67 -35 -34 0 .6 BP Bubble Point *DP Dew Point WO 93/14175 WO 9314175PCf/GB92/02384 11 TABLE 2

REFRIGERANT

Z BY WEIGHT R-12 E-125 /E-134a 100 75125 50/50 25/75

CONDENSER

PRESSURE (Bar)

EVAPORATOR

PRESSURE (Bar)

DISCHARGE

TEMPERATURE 0

C)

RETURN GAS TEMPERATURE (OC)

VOLUMETRIC

FLOW (H 3 Is x 102) COOLING DUTY PER UNIT SWEPT VOLUME (KW/m 3 COEFFICIENT OF

PERFORMANCE

BOILING BP* POINT (OC) DP** GLIDE IN EVAPORATOR (OC) 9.60 10.85 1.23 1 .38 9.*07 1.14 7 .73 0.96 120.8 90.2 91.4 92.0 20.0 20.7 20.8 20.5 0.140 0.149 0.173 0.200 714 1.90 -29.8 -29.8 0 671 1.70 -34.75 -32.15 1.7 578 1'.76 -30.60 -27.37 1.9 5 0 0) 1.78 -25.83 -23 .5 0 1.2 BP Bubble Point *DP Dew Point

Claims (12)

1. A refrigerant composition including from 25 to 50% by weight of difluoromethyl trifluoromethyl ether and from 75 to 50% by weight of 1,1,1,2-tetrafluoroethane.

2. A refrigerant composition as claimed in claim 1, consisting substantially of difluoromethyl trifluoromethyl ether and 1,1,1,2-tetrafluoroethane.

3. A refrigerant composition including difluoromethyl trifluoromethyl ether and fluoromethyl trifluoromethyl ether.

4. A refrigerant composition as claimed in claim 3, consisting substantially of difluoromethyl trifluoromethyl ether and fluoromethyl trifluoromethyl ether.

A refrigerant composition as claimed in claim 3 or claim 4, including from 25 to by weight of difluoromethyl trifluoromethyl ether and from 75 to 25% by weight of fluoromethyl trifluoromethyl ether.

6. A refrigerant composition consisting substantially of difluoromethyl trifluoromethyl 5 ether and bis(difluoromethyl) ether. S

7. A method fo; providing cooling which includes condensing a refrigerant composition including a mixture of difluoromethyl trifluoromethyl ether and at least one S other fluorine containing compound selected from the group consisting of fluoromethyl trifluoromethyl ether and bis(difluoromethyl) ether and thereafter evaporating it in a heat "0 ;0o exchange relationship with a body to be cooled.

8. A method for providing heating which includes condensing a refrigerant composition including a mixture of difluoromethyl trifluoromethyl ether and at least one other fluorine containing compound selected from the group consisting of fluoromethyl trifluoromethyl ether and bis(difluoromethyl) ether in a heat exchange relationship with a body to be heated and thereafter evaporating it.

9. A meth-d for providing cooling which includes condensing a refrigerant composition including from 25 to 50% by weight of difluoromethyl trifluoromethyl ether and from 75 to 50% by weight of 1,1,1,2-tetrafluoroethane and thereafter evaporating it in a heat exchange relationship with a body to be cooled.

10. A method for providing heating which includes condensing a refrigerant composition including from 25 to 50% by weight of difluoromethyl trifluoromethyl ether and from 75 to 50% by weight of 1,1,1,2-tetrafluoroethane in a heat exchange s relationship with a body to be heated and thereafter evaporating it. L

11. A heat transfer device containing a refrigerant composition as claimed in any one of claims 1 to 6.

12. A refrigerant composition as claimed in any one of claims 1, 3 and 6 substantially as hereinbefore described with reference to any one of the examples. DATED: 22 February, 1996 PHILLIPS ORMONDE FITZPATRICK Attorneys for: IMPERIAL CHEMICAL INDUSTRIES PLC I I I F e L i-i i -e INTEJRNATIONAL SEARCH REPORT. International Application No PCT/GB 92/02384 I. CLSSIFICATION OF SULWCTMATTU (If seve a lsificatloo sUhols ippyindicat J)C According to international Patent Cassification (IPC) or to both National Cassificaion and IPC Int.Cl. 5 C09K5/04 U. FIELDS SEARCHED Minimum Documentation Searched 7 Classification system assificaioti Symbols Int.C1. 5 C09K Documentation Searched other than Minimum Docu&mentation to the Extent that such Documents are Included in the Fields Searcheil U1I. DOCUMIENTS CONSIDERED TO BE RELEVANT 9 Category 0 Citation of Document, 11 with Indication, wlhere appropriate, of the relevant pasLs2 Relevant to Claim NoJ3 X DATABASE WPIL 1,3,4,11 Week 9122, Derwent Publications Ltd., London, GB; AN 91-159422 JP,A,3 093 883 (DAIKIN KOGYG) 18 April 1991 see abstract A EP,A,O 395 737 GRACE CO.) 1,12 September 1990 see the wthole document A WO,A,9 113 968 (DU PONT DE NEMOURS) 1-13 19 September 1991 see the whole document Special categories of cited documents: 10 Tr later document published after the International filing date A dotman defnin thegeneal tateof te ~or prioritydate and not in conflict with the application but A'dcundefi tohe f enerlaeancteci hc i o ted to unerstand the principle or theory untderlying the consderd t be f prtiularre~nceinvention 'E earlier document but published on or after the international -XI document of particular reancue; the claimed invention filing date cannot be considered nowel or cannot be considered to LV document which may throw doubts on priority claim(s) or Involve an inventive step which is cited to establish the publication date of another nf document of particular relevance; the claimed invention citation or other special reaon (a sSpecified) cannot be considered to Involve an inventive step when the 0' document "ef lg to an oral disclosure, use, exhibition or document Is combined with one or more other such docu- other mean menus, such comblnation bing obvious to a person skilled Pw document published prior to the international fling date but in the art. later than the priority date claimed W document member of the same patent family FV. CERTIFICATION Date of the Actual Completion of the International Search Date of Mailing of this International Search Report 24 MARCH 1993 2Bi14c3 International Searching Authority Signature of Authorizedl Officer EUROPEAN PATENT OFFCE PUETZ C. Fens PCTIL21 Imos 4shed)~1 4Jinr I"S PCT/GB 92/02384 International ADDlicittio No III. DOCUMET CONSIDERED TO BE RELEVANT (CONTINUED FROM THE SECOND SHEET) CategoryO Citation of Document, with Iodlad~oa, where appmoprate, of the relevant pags Rleangoilamo DATABASE WPIL Week 9122, Derwent Publications Ltd., London, GB; AN 91-159421 JP,A,3 093 882 (DAIKIN KOGYO) 18 April 1991 see abstract DATABASE WPIL Week 9221, Derwent Publications Ltd., London, GB; AN 92-172537 JP,A,4 110 386 (DAIKIN KOGYO) 10 April 1992 see abstract 1, 3,4, 11 1,11 Farm PCTIISAJ21O (extra mbd (Jemary ANNEX TO THE INTERNATIONAL SEARCH REPORT ON INTERNATIONAL PATENT APPLICATION NO. 9202384 68126 This anner lists the patent family memabers relating to the patent documents cted in fie above-mentioned international search report. The members are as contained in the European Patent Office EDP file on The European Patent Office is in no way liable for theme particulars which arm merely given for the purpose of information. 24/03/93 'W For more deta-is about this annex e Official Joual of the European Patent Office, No. 12/92 I