CA2231111A1

CA2231111A1 - Hydrofluorocarbon refrigerants

Info

Publication number: CA2231111A1
Application number: CA 2231111
Authority: CA
Inventors: Ian Robert Shankland; David Paul Wilson; Rajiv Ratna Singh
Original assignee: Individual
Current assignee: Honeywell International Inc
Priority date: 1995-09-14
Filing date: 1996-09-13
Publication date: 1997-03-20
Also published as: WO1997010312A1; EP0850286A1; JPH10511135A; AU6977696A

Abstract

This invention relates to hydroflurorocarbons useful in refrigeration and heat pump applications. The invention provides hydrofluorocarbons selected from the group of 1,1,2,3,3-pentafluoropropane, 1,1,1,3,3-pentafluoropropane, 1,1,1,2,3-pentafluoropropane, and mixtures thereof that are environmentally suitable replacements for chlorofluorocarbons in refrigeration applications such as centrifugal chillers.

Description

2 PCT~US96/14736 HYDROFI.UOROCARBON REFRIGERAMIS

Field of the Invention This invention relates to hydrofluorocarbons useful in refiigeration and heat pump appLications as well as foam blowing agents. More sperific~ lly, the invention provides l,ydlonuorocarbons that are e..v;.u.~ ly desirable rep!Ace....,.~ls for10 chlorofluorocarbons and hydrochlorofluorocarbons in refrigeraliion applications, such as centrifugal chillers, and foam blowi,.g agent applications.

Bac~ ~)u--d of the Invention Fluorocarbon based fluids have found widespread use in industry for 15 refrigeration applications such as air con~litioning and heat pump applicA~tione Vapor co",prcss;ol- is one type of refrigeration. In iltS ~ !e : form, vapor co--lples~ion involves cl1Allgii~ the .cLige.~.l from the liquid to the vapor phase through heat ~so,~lion at a low pressure and then ~from the vapor to the liquid phase through heat removal at an elevated p, ~,~;,u. c.
While the plilllaly purpose of refrigeration is to remove energy at low Le.--pc-ahlre, the plhlla~ ~ purpose of a heat pump is ~o add energy at higher ,p~,.alure. Heat pumps are considered reverse cycle systems because, for h~Ating the ope.alion of the con~ipnc~r is illLerchal ged with that of the 25 lt;Li~se~Lion e~apGl~or.

The art is cor~timl~lly seeking new fluorocarbon based ~~,Lige.~u-L~ and blowing agents that offer alternatives to fluids ~.;UI ~ LIy in use. Of particular interest as alh.,.ali~,es are fluorocarbon based compositions that are considered to 3 0 be enviroh.. .~ lly safe substitutes .

Ideally, reFIAc~m~rlt l-,rli clall~ co..,?osiLons possess those l~lo?c.~ies unique to the composition being ~placed inrlllding ehernical stability, low toxicity, non-fl~mm~bility, and efficiency-in-use. The latter characteristic is important in refrigeration and air-conditioning applications especially where a loss in refrigerant thermodynarnic pt;lrollllance or energy efficiency may have secondary environm~nt~l imp~r.t.c through increased fossil fuel usage arising from an increased r dem~n~l for electrical energy. Furthermore, the ideal substitute would not require major e~g;i~e~ ~ ing changes to conventional equipment currently used.

Previously, 1,1,2,2,3-pe~ n..Qropropane, HFC-245ca, has been proposed as an alternative to l, l-dichloro-2,2,2-trifluoroethane, R- 123, and trichlorofluorometh~ne, R-11. See N.D. Smith et aL, "R-245ca: A Potential Far Term Alternative For R-11", 35 ASHRAE J. 19 -23 (1993). The present invention provides additional compounds and compositions that are suitable replacements for R- 11 and, in addition, may be used as foam blowing agents.

De3~ )lion ofthe Invention In accordance with the invention, it has been discovered that the compounds 1,1,1,2,3-pPnt~flllQtupl~,palle ("HFC-245eb"), 1,1,1,3,3-pent~fl-lolopropane ("HFC-245fa"), 1,1,2,3,3-pent~fll-olopl~,palle ("HFC-245ea"), and mixtures thereof are useful as l~Çlig~ s, heat ~I~l..r~. fluids, and 2 o blowing agents. More specifically it has been discovered that these compounds and ll~lules meet the need for a no~n~ hlc refrigerant which has a low ozone depletion pot~ l;al and is a negligihle contributor to green-house global warming colll?a~ed with currently used refrigerants, such as R-l l and 123. Further, it has been discovered that these compounds and mixtures have COP's and capacities 2 5 that render them suitable for use in refrigeration applications, int~ 1ing in centrifugal chillers. Also, the compounds and mixtures of the invention exhibit low co,llprcssor dischalge t~ pe.dlures.

For purposes of the invention, by centrifugal chillers is meant refrigeration 3o eq~ip~ nt that uses centrifugal coll-plts~ion to COIllplCSS the refrigerant.
In one ensbodiment, the invention provides a method for producing refrigeration using a compound selected from HFC-245eb, HFC-245fa, HFC-W O 97/10312 PCT~US96/14736 245ea, and mixtures thereof. In still another embodiment, a method for producingrefrigeration using a centrifilgal chiller is provided using a compound selected from HFC-245eb, HFC-245fa, HFC-245ea, and mixtures thereof. In another embodiment of the invention, a method for produciing heating is provided using acompound s~lected from HFC-245eb, HFC-245fa, ~C-245ea, and mixtures thereof. For purposes of this invention, by rnixture:s is meant both nonazeotropic and azeollope-like compositions of at least two ofthe compounds.

Thus, in yet another embodiment, this invention provides azeotrope-like compositions comprising effective amounts of at least two colllpounds s~lected from HFC-245eb, HFC -245fa, and HFC-245ea. E~y effective amount is meant an amount of each component that, when co,-,bined with the other component, resultsin the formation of an aLeotlope or azeo~lopc-like mixture. Plere.ably, the invention provides azeol~ope-like compositions co~ lising from about lO to about90 weight percent 245fa and from about 90 to about lO weight percent 245ea, the compositions having a boiling point 25~ C +7~ C at: 760 mm Hg. More pr~;rel~bly,the composition comprises from about 30 to about 70 weight percent HFC-245fa and from about 70 to about 30 weight percent HF('-245ea, more pl~ bly about 50 weight percent HFC-245fa and about 50 weight percent E~C-245ea.
For purposes of this invention, azec,~lope-like composi~ions are colnl)os;liolls that behave like aLeoL,o~ic mixtures. From filnd~m~nt~l principles, the thermodynamic state of a fluid is defined by pre~ssure, temperature, liquid colllpos;lion, and vapor composition. An azeollopic mixture is a system of two or 2 5 more colllpon~ s in which the liquid composition and vapor composition are equal at the state pressure and te.l.p~.~Lure. In practice, ~his means that the components of an azeoL~upic mixture are con~ t boiling and cannot be s~pa,aLed during a phase change.

3 o Azeol,ope like compositions behave like az~eo~, opic mixtures, L~, or are CQn'~ boiling or essenti~lly con~ l boiling. In other words, for azeotrope-like compositionc~ the composition of the vapor formed during boiling or evapora~ion is W O 97/10312 PCT~US96/14736 identical, or subst~nti~lly identical, to the original liquid composition. Thus, with boiling or evaporation, the liquid composition changes, if at all, only to a minim~l or ne~ligible extent. This is to be contrasted with nonazeotrope-like compositions in which, during boiling or evaporation, the liquid composition changes to a 5 substantial degree.

The compounds and nli~lules ofthe invention may be used in a method for producing refrigeration that comprises condencing a refrigerant and thereafter evapol alhlg the refrigerant in the vicinity of a body to be cooled. Alternatively, the 10 compounds and mixtures of the invention may be used in a method for producingheating which conl~li3es conrlçnging a refrigerant in the vicinity of a body to be heated and therea~er evaporating the refrigerant.

In yet another embodiment, the compounds and llliAIUl~,S of the invention 15 may be used in a method.for producing refrigeration using a c~ntrifi~g~l chiller that co~ ises co",pl~s;ng the compound or mixture of the invention by centrifi~gal con,pre~ion and evapo~aling the refrigerant in the vicinity of a body to be cooled.

In still another embo~lim~ont~ the compounds and mixtures of the present 2 o invention may be used in a method for producing foam comprising blending a heat pl~cl;..;,,d resin with a volatile blowing agent comprising the fluids ofthe present invention and introducing the resin/volatile blowing agent blend into a zone of lower p[e~ .u,~ to cause fo~ming 2 5 In yet another embodiment the compounds and mixtures of the present invention may also be used in a method of dissolving c0~ 5 or removing con~ nl c from the surface of a substrate which comprises the step of cont~ctir.g the substrate with the compositions of the present invention. In another embodiment, the compounds and mixtures of the present invention may also be used as fire e~ctin~ishing agents.

W O 97J10312 PCT~US96/14736 . 5 The compounds and mixtures of the preserlt invention are known materials. Preferably, the materials should be used in sufficiently high purity so as to avoid the introduction of adverse infl~lencP5 upon the cooling or heating properties, constant-boiling properties, or blowing agent properties of the system.

Additional components may be added to the compounds and compositions of this invention to tailor their propellies acco-ding to the need. For example, in the art, pro~arle may be added to refrigerant compositions to aid oil solubility and may be added to the fluids of the present invention. Nitrom~oth~nç may also be 0 added as a stabilizer. Similar materials may be added to the present compositions~

The present invention is more fully illustrated by the following non-limiting s EXAMPLE I
The critical t~mp~ lule of ~C-245ea was meacured by me~cllring the te~llpel~Lult; where the m~niscl~c between the liquid and vapor phase disappea.t;d and was found to be 193.0~ C.

2 o EXAMPLE 2 The liquid density of material HFC-245ea was measured, as a function of t~n~pel~lule, using glass flotation beads of precisely known denci~ies The following data were obtained:

W O 97/10312 PCT~US96/14736 Table I
Te,ni)e.~LLIre (C) Density (~/cc) 191.10 0.69887 185.86 0.79875 175.99 0.89868 161.26 0.99867 140.05 1.09876 113.75 1.19895 81.00 1.29928 42.74 1.39974 -0.27 1.50033 The vapor pressure of ~C-245ea was measured by loading a sample of 5 the material in a stainl~Cc steel cylinder and placing the cylinder in a t~..,pe.~ re controlled bath. The cylinder was connected to a pressure tr~nC~Ilcer. The following data were obtained:

Table 2 Tc.l-~e.al-lre (C) Pressure (psia) ~~~ 2.50 12.06 4.60 22.08 6.80 26.10 8.30 39.16 14.10 42.13 16.20 58.92 28.30 76.55 48.50 91.53 74.30 The critical temperature of HFC-245eb was measured by measuring the temperature where the m~niccl~s b~ . ell the liquid and vapor phase disappeared and was found to be 164.90~ C.

The liquid density of material ~C-245eb was measured as a fiunction of te",~ re using glass flotation beads of precisely hlown densities. The 5 following data were obtained:

Table 3 Te.llp .. aL.Ire (C) Density (s~/cc) -27.36 1.50073 14.19 1.40012 51.67 1 2~964 84.02 1.19930 110.40 1.09908 131.59 0.99896 146.66 0.89893 156.95 0.79897 162.40 0.69906 The vapor pressure of E~C-245eb was measured by loading a sample of the material in a ~Laillless steel cylinder and placing ~he cylinder in a temperature controlled bath. The cylinder was conn.octed to a pressure tr~n~duc~r. The following data were obtained:

WO 97/10312 PCT~US96/14736 Table 4 Temperature (C) Pressure (psia) -20.85 l.go -14.89 2.60 0.00 5.50 6.11 7.40 9.66 8.60 15.08 lo.go 20.34 13.so 21.13 13.90 23.86 15.30 39.38 27.20 54.69 44.80 67.79 66.30 33.65 22.30 33 57 22.20 40.26 27.80 40.25 27.80 123.68 239.50 140.54 330.00 155.56 419 30 The vapor pressure of ~C-245fa was measured by loading a sample of the material in a s~inl~c~ steel cylinder and placing the cylinder in a t- .llpel~ re controlled bath. The cylinder was connrc~ed to a pressure tr~n~d~lçPr. The following data were obtained:

w o 97J~a312 PCTAUS96/14736 Table 5 Temperature (C) Pressure (psia) -29.10 1.83 -20.84 2.85 -10.09 4.81 0.01 7.88 12.0~ 13.02 12.05 13.13 14.05 14.22 14.06 14.27 14.60 14.58 16.34 15.62 20.47 18.30 Example 8 This .oY~mple shows that ~C-245ea, HFC-245fa and HFC-245eb have ~ 5 certain advantages when co~ t;d to other refrigerants which are currently used in certain refrigeration cycles.

The theoretical pe.roln~ce of a lerlig~ at specific op~,~a~ing conditions can be e,~ ed from the thennodynarnic plopci. lies of the refrigerant using lo standard refrigeration cycle analysis techniques as described, for example, in RC
Downing, Fluorocarbon Refrigerants Handbook Chapter 3, Prentice-Hall, 1988.
The coeffici~nt of pc.ru.l..allce, COP is a universally accepted measure, especially useful ;n ~c~- ~v .l ;ng the relative ther nodynamic efl~lciency of a refrigerant in a specific heating or cooling cycle involving evaporation or condene~tiQn of the 15 refrigerant. In refrigeration ~ngineering, this term expresses the ratio of useful refrigeration to the energy applied by the co.llplessor in colllpl~;s~.ing the vapor.
The capacity of a refrigerant I epres_.lL~. the volumetric efflciency of the refrigerant.
To a cG..lpl~ssor ~ngine~or~ this value expresses the c~apability of a conll)ressor to pump q~l~ntities of heat for a given volumetric flow rate of refrigerant. In other 2 o words, given a specific CGlllpl cssor, a refl i~,c~ ant with a higher capacity will deliver more cooling or heating power.

W O 97/10312 PCT~US96/14736 We have pclÇu,llled this type of calculation for a water chiller refrigeration cycle where the condenser temperature is typically 100~ F and the evaporator teml)cl~L-Ire is typically 30~ F. We have further ac~ ed colllplc~sion efficiency of 5 80 % in a saturated cycle. The compressor has a displ~cem~Pnt of 1000 cubic feet per hour. Such c~lc~ tions were performed for HFC-245ea, HFC-245eb and HFC-245fa and for R-123. R-123 is plcsen~ly being used as an alternative for R-11 in centrifilgal chillers. Table 6 lists the COP, discharge te~llp~ Luft and capacity of the various refrigerants.

Table 6 R-123 HFC-245fa HFC-245ea E~C-245eb COP 4.90 4.74 4.94 4.82 Capacity 8234 12752 4937 9767 (~) Temp. 114 103 116 107 Colllprcssion Ratio 4.58 4.48 5.66 4.76 It can be seen that, conlpa.ed to the c,~isling alternatives to R-l l, such as R-123, HFC-245fa and 245eb have higher refrigeration capacity. HFC-245fa and 15 245eb have lower colll~re~ion ratios which ratios are advantageous from the point of in~..,~ed reliability of ~p~h~ cal m~hinPry in which these refrigerantsarc likely to be employed. Also, HFC-245ea exhibits higher energy Pffi~iPnCy in colllp~ison to the other fluids.

~ppl~ tely 10 g HFC-245fa were added to the rererence and sample "
arms of a ~li~re.llial ebulliometer to obtain boiling point measu. t:llle.lls. See W.
Swietoslawski, Ebulliometric Measul~.lle.l~ (1945). The system was brought to total reflux by gently heating the lower part of the ebulliometer. The temperature 2 5 of the boiling liquid was measured with reference to pure ~C-245fa using a W O 97/10312 PCT~US96/14736 m~trhed pair ofthermistors precise to i 0.01~ C~ Boiling points were recorded after steady state was attained. Aliquots of HFC-245ea were added to the sample side and the change in boiling te-n~ re noted. Dlata was obtained up to appro~ ately 42 weight percent of HE~C-245ea and indicated that the two 5 components formed a constant boiling composition c)ver a range of compositionsof the two components. The boiling point at 760 mm Hg was constant within 2~ C
firom about 1 to about 27 weight percent ~C-245ea and from about 99 to about 73 weight percent HFC-245fa.

Table 7 Weight Po~nt 245CI BP (~C~Weight Pe~ent 245ea BP (~C) 0 14.5 9.7 16.0 0.4 14.6 10.0 16.0 0.7 14.~ 10.3 16.0 1.1 14.7 10.6 16.0 1.4 14.8 10.9 16.1 1.8 14.9 11.1 16.1 2.1 14.9 11.4 16.2 2.4 15.0 Il.~ 16.2 2.8 15.0 12.0 16.2 3.1 15.1 12.3 16.2 3.5 15.1 12.8 16.3 3.8 15.2 13.9 16.4 4.1 15.2 15.0 16.5 4.4 15.3 17.4 16.8 4.8 15.3 19.8 17.0 5.1 15.4 22.0 17.2 5.4 15.4 24.2 17.4 5.7 15.5 26.2 17.6 6.1 15.5 26.2 17.6 6.4 15.6 28.1 1~.8 6.7 15.6 29.9 17.9 7.0 15.6 31.6 18.1 7.3 15.~ 33.2 18.3 7.6 15.7 34.8 18.6 7.9 15.7 36.3 19.2 8.2 15.8 37.7 19.7 8.5 15.8 39.1 19.9 8.8 15.9 40.4 19.9 9.1 15.9 41.6 20.1 9.4 16.0 42.8 20.4 The data from Table 7 may be co-l-pa~- ed to the boiling point of the HFC-245fa/HFC-245ea n~ixture obtained accor-ling to Raoult's Law. The co---pa,ison, 5 illustrated on Table 8, shows that the actual boiling point does not change as much W ~ 97~10312 PCT~US96/14736 on the addition of HFC-245ea as is predicted and the mixture therefore, is unexpectedly constant boiling.

t Table 8 Wt % 245fa Actual BP (o C) Raoult s Law BP (o C) 1 14.5 1~.6 lS.3 15.4 16.0 16.3 17.0 18.1 17.9 20 19.8 22.1 23.2 2~.4 ~~d v.lue FY~mrle 10 From the data of Example 9 -the theoretical pe,ru,l,-ance of rnixtures of 30/70 weight percent, 50!50 weight percent, and 70/30 weight percent HFC-245fal~C-245ea are c~lç~ t~d using the method of Example 8. The c~lcnl~ti~ n is pclru""ed for a water chiller refrigeration cycle in which the condenser te",p~ .aL~Ire is typically 100~ F and the e~,a~)o,aLor te."~.aL.Ire is 30~ F.
Co",~ ion e~ ncy of 80 % in a saturated cycle is ~e-lme~l The comp-essor disphcement is 1000 cubic feet per hour. The results are that ~he compositions 15 have rcLi~e. alion ç~paciti~e closer to R- 1 1 than either of the two components singly and thus, are suitable repl~c~ for those en~iro~ ly undesirable refrigerants ~;u~ Lly used in chiller applications.

..

Claims

What is claimed is

1. A method for producing refrigeration comprising condensing a refrigerant which is an azeotrope-like composition consisting essentially of at least two ompounds selected from the group consisting of 1,1,1,2,3-pentafluoropropane, 1,1,1,3,3-pentafluoropropane, 1,1,2,3,3-pentafluoropropane, and mixtures thereof, and thereafter evaporating the refrigerant in the vicinity of a body to be cooled.

2. The method of claim 1 wherein the refrigerant is a mixture which is an azeotrope-like composition consisting essentially of 1,1,1,2,3-pentafluoropropane and 1,1,1,3,3-pentafluoropropane.

3. The method of claim 1 wherein the refrigerant is a mixture which is an azeotrope-like composition consisting essentially of 1,1,1,2,3-pentafluoropropane and 1,1,2,3,3-pentafluoropropane.

4. The method of claim 1 wherein the refrigerant is a mixture which is an azeotrope-like composition consisting essentially of 1,1,1,3,3-pentafluoropropane and 1,1,2,3,3-pentafluoropropane.

5. A method for producing refrigeration using a centrifugal chiller comprising compressing a refrigerant selected from the group consisting of 1,1,1,2,3-pentafluoropropane, 1,1,1,3,3-pentafluoropropane, 1,1,2,3,3-pentafluoropropane, and mixtures thereof, and thereafter evaporating the refrigerant in the vicinity of a body to be cooled.

6. The method of claim 5 wherein the refrigerant is 1,1,1,3,3-pentafluoropropane.

7. The method of claim 5 wherein the refrigerant is 1,1,2,3,3-pentafluoropropane.

8. The method of claim 5 wherein the refrigerant is a mixture which is a nonazeotropic composition comprising at least two compounds selected from the group consisting essentially of 1,1,1,2,3-pentafluoropropane, 1,1,1,3,3-pentafluoropropane, and 1,1,2,3,3-pentafluoropropane.

9. The method of claim 5 wherein the refrigerant is a mixture which is an azeotrope-like composition consisting essentially of at least two compounds selected from the group consisting essentially of 1,1,1,2,3-pentafluoropropane, 1,1,1,3,3-pentafluoropropane, and 1,1,2,3,3-pentafluoropropane.

10. The method of claim 5 wherein the refrigerant is a mixture which is a nonazeotropic composition comprising 1,1,1,2,3-pentafluoropropane and 1,1,1,3,3-pentafluoropropane.

11. The method of claim 5 wherein the refrigerant is a mixture which is an azeotrope-like composition consisting essentially of 1,1,1,2,3-pentafluoropropane and 1,1,1,3,3-pentafluoropropane.

12. The method of claims 5 wherein the refrigerant is a mixture which is a nonazeotropic composition comprising 1,1,1,2,3-pentafluoropropane and 1,1,2,3,3-pentafluoropropane.

13. The method of claim 5 wherein the refrigerant is a mixture which is an azeotrope-like composition consisting essentially of 1,1,1,2,3-pentafluoropropane and 1,1,2,3,3-pentafluoropropane.

14. The method of claim 5 wherein the refrigerant is a mixture which is a nonazeotropic composition comprising 1,1,1,3,3-pentafluoropropane and 1,1,2,3,3-pentafluoropropane.

15. The method of claim 5 wherein the refrigerant is a mixture which is an azeotrope-like composition consisting essentially of 1,1,1,3,3-pentafluoropropane and 1,1,2,3,3-pentafluoropropane.

16. The azeotrope-like composition consisting essentially of effective amounts of 1,1,1,3,3-pentafluoropropane and 1,1,2,3,3-pentafluoropropane which composition boils at 25° C ~ 7° at 760 mm Hg.