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Патент USA US2104882

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Jara. il, 1938.
T. MIDGLEY, JR.. ET AL
~
2,104,882
HEAT TRANSFER AND REFRIGERATION
‘
Original Filed NOV. 19, 193]
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INVENTORS
Thoma.:
Mid9 /e.y J'.e,
Alberi' L. Henne, and
‘ÃÉÍZÍF
` Z BY Pobcfr R New
ATTORNEYS
2,104,882
Patented Jan. li, 1938
TESv
treoA
PATENT OFFICE
-`2,104,882
l'HEAT TRANSFER AND REFRIGERATION
Thomas Midgley, Jr., Worthington, Albert L.
Henne, Columbus, and Robert R. McNary, Day
ton, Ohio,'assignors to General Motors Corpo
ration, Dayton, Ohio, a corporation _of Dela
x
original application November-:19, 1931, serial
Divided and this application May
1, 1934,' Serial N0. 723,372
` N0. 576,052.
(Cyl. l62---178)
s claims.
This application relates to the art of trans
ferring heat from one point to another and spe
cifìcally to the art of refrigeration and is a' divi
Because there are several variables, and be
cause- of the value of relative proportions, we have
placed the compounds of the group just discussed
sion of application Serial Number 516,052, pat
on plots wherein
ented July 31, 1934, No. 1,968,049.
A
p
Heretofore, as far as we are aware, refrigerants
and heat transfer agents have been chosen chiefly
for their boiling points and stability in the re
frigerati'ng or heat transfer cycle irrespective of
I
V
mability and non-toxicity.
corresponding to the numbers used in Fig. 2.'
Referring to the plots generally, the dashed
_It is the object of our invention, on the other
hand', to provide a process of refrigeration and,
lines indicate chlorine substitution.
other desirableproperties, such as non-infiam
generically, a process of heat transfer in which
15 these desirable properties, such as 'non-innam
mability and non-toxicity, are obtained- in com
lines indicate fluorine substitutions and the solid
SimilarV plots
are obtained with bromine and iodine in place of
chlorine except that the plot is elongated in the
direction of higher temperatures with bromine,
,
while with iodine the temperatures are still more
Broadly stated, the part of our processwhich
elevated. The amount of elongation is readily de
termined by applying the boiling points of some of
bination with the desired boiling points.
‘
deals with the controllingof the properties of the
20 refrigerating or heat transfer agents consists in
these compounds.
,
_
replacing hydrogen by iluorine or otherhalogen,
Referring speciñcally to Fig. y1, this plot con
or both, in aliphatic hydrocarbons in which at
least one hydrogen has already been replaced by
tains all the compounds which» can be derived
fluorine.
25
'
Fig. l is a plot applying the rules of substitution Ul
to typical groups having one carbon atom,
Fig. 2 is a plot applying the rules to groups hav
ing two carbon atoms, and
.
Fig. 3 is a key to Fig. 2, showing the radicals
,
’
,
`
Broadly stated, the <part of our process which
relates to the` transfer of heat or the production
of refrigeration comprises changing. the physical
Y state of,- for example, by condensing or evaporat
ing,_a halo-iiuoro derivative of an aliphatic hy
from CHaF by chlorine and/or fluoriñe substitu
tions, together with data which assist in the for
mation of the plot. On the base line appear the.
numerals zero to` four which show halogen Vcon
tent, and the vertical line gives the approximate
boiling points in degrees centigrade. At each
point of intersection is given the chlorine and
30 drocarbon, and dissipating to, or withdrawing
iiuorlne content and the complete formula of the
from, an object to be heated or cooled, thelatent
heat necessary for changing the physical state of
the said derivative. By a halo-nuoro derivative
corresponding compound is found by making this
halogen substitution for hydrogen in the formula
of an aliphatic hydrocarbon we mean aderivative
at about _25° centigrade to indicate approxi
' containing more than one ñuorlne atom with or
‘without other halogen atoms, or one ñuorine atom
with one or more other halogen atoms.
Referring now speciñcally to oui- mode of con-4
trolling the properties of the refrigerating or heat
40 .transfer agent, aliphatic monoñuorides form the
structural nucleus on which the agents are built.
Broadly speaking, if in the structural formula
CHSF we increase the ñuorine content (number of
atoms) by the substitution of fluorine for hydro
gen, the boiling point decreases, stability increases,
CH4.
We have drawn a horizontal dashed line
mately the optimum vapor pressure conditions “
which we desire for operating an air cooled re
frigerator. It is obvious that one may deviate
more or less from this line to obtain optimum
conditions which include someA other factors, so
that within the neighborhood of this line we can
provide a suitable refrigerant to meet a wide vari
>ation in limitations imposed. If under other re
frigerating conditions another optimum line is“
found desirable, the same choice may be made'in
inñammability decreases, and toxicity decreases.
the neighborhood of that line. In fact, the actual
operation of the refrigerator and the providing of
If we keep the fluorine contentconstant and sub
the characteristics of the refrigerant are here
stitute another halogen for` hydrogen in the
nucleus, the stability decreases, the toxicity in
desirable process of refrigeration under a given
combined as one problem so as to obtain the most
50
creases, -and the .inñammability decreases. 'The
set of conditions.
,
I
In Fig. 2 we have shown the same mode of
degree to which these variations take place de
pends on what the other halogen (chlorine, controlling the properties of a refrigerant carried
to compounds of the same type as in Fig. 1 but
bromine, or iodine) is. `As the ratio ofthe halo
gen content to the hydrogen content increases the , having two carbon atoms.A The key to the chart
A55 iniiammability decreases.
is given in Fig. 3. For example, compound 0.1 is
2,10%@82
2
CH3.CH2F, compound 2.9 is CHFaCCl-ZF, com
pound 1.5 is CHzFCI-IClz, _and compound 2.2 is
CHFz.CHFz.
When We choose as our nucleus a compound
having'two or more carbon atoms We find that
the structural formula gives a choice as to Where
the substitutions of the halogens shall be made.
For example, the structural formula of C‘2H5F is
CHsCHzF, which has a boiling point at about
derivative which contains more than one fluorine
atom with or without other halogen atoms, or one
ñuorine atom with one or more other halogen
atoms, and by dissipating to or withdrawing from
an object to be heated or cooled, the latent heat
necessary for the change in physical state. More
specifically, to produce refrigeration, we may
evaporate the desired derivative in the vicinity
of a body to be cooled, while if a heating effect
_32° C. If we_make a fiuorine substitution for
is desired, we may condense the derivative in the
vicinity of a body to be heated, it being under
refrigerating agent whose boiling point is about
stood, of course, that the terms “evaporation”
and “condensation” include the separation of a
gas from, and the absorption of a gas in, an ab
10 hydrogen in the second radical of this structural
formula so that it reads GHz-CHFz we have a
_26° C. If we make the fluorine substitution for
hydrogen onto the other carbon atom so that the
15 formula reads CHzF-_CHzF the boiling point of
this refrigerant is about _5° C. Thus the ñrst
type of substitution yields a compound boiling
substantially lower than the compound obtained
by the second type of substitution and the chart
20 shows this to be> general. The substitution of
chlorine, bromine or iodine for hydrogen raises
the boiling point, but the substitution in a radical
which does not already contain a halogen raises
the boiling point more than when the substitu25 tion is made in a radical which already contains a
halogen.
I
v
The plot may be expanded in like manner with
other aliphatic mono-iluorides. As the number of
carbon atoms increases the complexity and ex
tent of the plot will increase together with the
number of halogens present. These halogen
derivatives of aliphatic mono-fluorides may be
represented b-y the formula
35
sorbent respectively.
15
^
Our invention will probably ñnd its greatest
utility by adjusting both the mode of preparing
the refrigerant to obtain desirable characteristics
and the mode of using the refrigerant to obtain
a process of refrigeration or heat transfer which 20
meets the limitations imposed. We prefer to
employ refrigerants boiling above _60° C.
Obviously our invention is not limited in its
application to any specific form of apparatus for
carrying out the mode of operation described and
it will not be necessary for a complete under
standing of the invention to show a specific em
bodiment of apparatus. Nor is the present inven
tion limited to the examples set forth, for a par
ticular advance of the present invention resides 30
in the fact that a great number of new refriger
ants with graduated properties is rendered avail
able, and that one is accordingly enabled to se
cure the most suitable refrigerant for varied pur
poses.
W'hat is claimed is as follows:
1. The process of transferring heat which com
C represents carbon and n the number of car- -
bon atoms in the molecule which is always equal
to one or more.
40
'
.
2. The process of transferring heat which com
40
prises condensing and subsequently evaporating
CHsCClzF.
fulfill the requirements of our invention,
.
' F represents fluorine and p the number of
prises condensing and subsequently evaporating
more.
_
_
X represents chlorine, bromine or iodine or
combinations thereof and r the total number of
such atoms. r may be zero when p is greater
than one.
50
CHaCClFz.
H represents hydrogen and m the number of
atoms thereof, which may equal zero and still
atoms thereof which is always equal to one or
45
prises condensing and subsequently evaporating
v
3. The process of transferring heat which com
a halo-fluoro derivative of ethan -having the
general formula CzHaXmF(3-m) where X equals a
halogen other than fluorine and is never‘less
than one.
.
4. The process of transferring heat which com
prises condensing and subsequently evaporating
Among the chemical groups that these re
frigerants fall in are halogen derivatives of all
a halo-fluoro derivative of ethan having the
general formula C2H3ClmF(3_m) where m is never
phatic mono-fluorides, halogen derivatives of
less than one,
alkylv mono-fiuorides, aliphatic fluoro halides,
alkyl iiuoro halides, fluoro derivatives of methyl
lfluoride, ?luoro-halo derivatives of methane and
fluoro chloro derivatives of methane.
Thus by our mode of making fiuorine and/or
Aother halogen substitution in a mono-fluoride, We
can meet any conditions of Arefrigeration and
provide our refrigerant with the desired proper
ties, such as non-toxicity and non-infiammabili
ty, along with such properties as stability and
proper boiling points.
Referring more specifically to the part of our
65 process which relates to the actual transfer of
heat, We accomplish this transfer of heat by
\ changing the physical state of, for example, con
densing or evaporating our aliphatic hydrocarbon
‘
5. The process of transferring heat which com
prises condensing and subsequently evaporating `
any halo-nuoro derivative of ethane having the
general formula CzHnXmFs-(Mm) , where X equals
a halogen other than ñuorine and 11. and m are
never less than one.
-
‘
6. The process of producing refrigeration 60
which comprises evaporating in the vicinity of a
body to be cooled and subsequently condensing
any halo-fluoro derivative of ethane having they -
general formula czHnXmFs- (Mm) , where X equals
a halogen other than ñuorine and n and m are 65
never less than one.
'THOMAS MIDGLEY, JR.
ALBERT L. HENNE.
ROBERT R. MCNARY.
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