Note: Descriptions are shown in the official language in which they were submitted.
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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,
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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-
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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
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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.
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. 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:
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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
EXAMPLE 3
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
EXAMPLE 4
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.
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EXAMPLE 5
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
EXAMPLE 6
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:
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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
EXAMPLE 7
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:
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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.
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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.
EXAMPLE 9
~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
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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.
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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
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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.
..
