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Oct. 8,1946. ‘
Filed Jan. 15, 1940
2 Sheet‘s-Sheet 1
. Oct- 3, 1946-
e. w. MILLER El'AL
Filed Jan. 15, 1940
2 Sheets-Sheet 2
‘M {$44M .
Patented Oct. 8, 1946
Glen W. Miller, Glendale, Edward L. Kells,
Montrose, and Delmar H. Larsen, Los Angeles,
Application January 15, 1940, Serial No. 313,858
9 Claims.
(Cl. 62-119)
This invention relates to the art of absorption
refrigeration, and embodies a new and useful
type of absorption cycle using new combinations
of absorbent and refrigerant.
One of the objects of the invention is to pro
vide a new cycle in that low boiler temperatures
are thereby made possible.
Another object is to provide ameans of using re
frigerant-solvent combinations otherwise unutili
zable because of relatively high solvent Volatility. 10
the difference in boiling points is much less than
240 deg. F. and which di?erence may be as low
as 91 deg. F. and is preferably not more than 150
deg. F. In order to utilize these combinations
efficiently, it is necessary when heat is applied to
the refrigerant-solvent combination to secure a
separation into a relatively pure solvent return
The foregoing and many other speci?c features
of the invention are set forth in the following
and a relatively pure refrigerant return, This
is accomplished by the substitution of a fraction
ating tower for the usual boiler and analyzer,
wherein the solution passes preferably into the
fractionating tower at a point wherein the liquid
present in the fractionating tower has approxi
mately the same composition and temperature as
the solution from the absorber and applying heat
to the solvent.
It has always been recognized that a really
effective solvent should be quite non-volatile with
respect to the refrigerant in order that the sepa
ration of the two by the applied heat may be as
complete as possible. For example, the combina
tion of ammonia with water is commonly used;
water with sulphuric acid; and gaseous chloro
speci?cation, where we describe what we con
fluorohydrocarbons with high boiling organic sol
Another object is to disclose several novel re-‘
frigerant-solvent combinations, and their method
of use.
Another object is to disclose the application
of an internally energized pump to absorption
refrigeration machines which will permit hermetic
sealing of the machine and effect certain econ
Another object is to provide a means of obtain
ing both pure solvent return and low boiler tem
vents of the “plasticizer” type are combinations
sider the preferred embodiments of the inven
which have also been employed. In all of these,
tion. These are illustrated in the accompanyingv
there exists a su?icientlylarge difference in vola
drawings where-—
tilities that simple heating suf?ces to drive
Figure 1 is a diagrammatic drawing of the
enough refrigerant in a relatively pure state from
cycle in which the transfer of ?uid is effected by
an internally energized pump.
30 the refrigerant-solvent elllux of the absorber to
continue the operation of the cycle.
Figure 2 discloses the invention as applied to
The apparatus usually employed to separate the
a three ?uid, or diffusion absorption cycle.
refrigerant from the solvent-refrigerant mixture
In absorption refrigeration systems, the refrig
consists of a container wherein heat may be sup
erating effect is produced by the evaporation of
a liquid refrigerant by allowing it to expand from O: CH plied to the introduced mixture, whereby some of
the refrigerant therein is driven off. Often a
a pressure greater than its vapor pressure at cool
few entrainment plates, comprising what ‘is
ing water temperature to a pressure less than its
known as the analyzer, are placed above the boil
vapor pressure at the refrigerating temperature.
er, and sometimes a so-called dephlegmater, a
In order to re-cycle the refrigerant, it is absorbed
into a liquid of high solvent power; thus dis 40 partial condenser, is placed above the analyzer.
However, these last two devices serve principally
solved, it is pumped to the higher pressure and
to enrich the refrigerant, and have only a rela
driven from the solvent by heat. The function of
tively small enriching e?ect upon the solvent
the solvent is thus to reduce to a minimum the
refrigerant mixture in the boiler, which is gen
mechanical work necessary in bridging the low
and high pressure sides of this system, since the 45 erally drawn off for re-cycling from the same
container which it enters from ‘the absorber.
volume of the refrigerant as pumped is reduced.
It has generally been considered that the re—
The remainder of the necessary energy used to
frigerant and solvent must differ greatly in
drive the refrigerant from this solution can then I
‘ volatility in order that the former may be readily
be supplied by heat.
There are, however, great disadvantages to the 50 driven off from the latter in the still, as has been
mentioned. For example, the boiling points (at
present combinations of refrigerant and solvent
atmospheric pressure) of ammonia and water
either as a ?re hazard or danger of the escape
differ by 240 deg. F. This great difference en
of a gas poisonous to the human system. Here
ables the ammonia driven o? to be relatively an
tofore, the selection of refrigerants and solvents
has been limited because of the necessity of main 55 hydrous, but if ammonia-free ‘water were desired
to issue from the boiler, it would require for the
taining a large difference in the boiling points
usual cooling water temperature available, a
of the refrigerant and solvent; as for example,
boiler temperature in the neighborhood of 390
ammonia and water boiling points differ by 240 I
deg. F. Accordingly, in the usual ammonia
deg. F. However, by the method of refrigeration
which we disclose herein, it is possible to use com 60 water absorption machine, the solvent returned
to the absorber contains in the neighborhood of
binations of refrigerants and solvents wherein
20% ammonia. The present invention comprises,
an external source of energy, gives continuous
operation and rids the machine ofpany packing
aside from features mentioned hereinafter, a
means of securing both low boiler temperatures
and pure solvent return, in that a solvent is
chosen having a boiling point (at atmospheric
pressure) not to exceed by more than 150 deg. F.
that of the refrigerant, and in that both refrig
glands. Used in a machine with a customary
generator as the separating means this device
should be slightly less e?icient than the pressure
equalizing devices but affords great advantages
in allowing the use of an adequate heat exchanger
between ‘the absorber and separating means.
erant and solvent are obtained in a relatively
However the vapor driving the pump, just as the
pure state by the substitution of a fractionating
tower for the usual boiler and analyzer. It is 10 vapor needed to equalize the pressures, would be
largely refrigerant vapor, or at least the vapor
also highly desirable that the low side pressure
that ordinarily goes to the recti?er and thus
much refrigerant would be returned to the ab
sorber without being expanded in the evaporator
and usefully absorbing heat. If, however, as is
proposed'here, such‘aproposed pump is used in
connection with a fractionating tower, it is ap
parent that substantially pure solvent vapor is
that is, the pressure prevailing in the absorber
be not excessively low, say not less than lit/sq. in.
abs., as otherwise in practice it becomes virtually
impossible to maintain'the system free from air
?ltered in through ‘leaks in the system. To be
sure, so-called-di?usion machines have been con
structed which employ an inert gas to build up
the-total pressure in the low pressure side of the
available near the base of the tower and can be
apparatus, but many complications are thereby 20 used to drive the pump. This vapor can then
be exhausted into the absorber without a loss of
introduced which'make it highly desirable from
refrigerant, the only loss being the heat neces
a practical standpoint to dispense with the use
of-an-inert gas whenever possible.
sary to do the pumping and a, slight increase in
‘ Intwo ?uid absorption machines a pump is
the heat abstracted by the cooling coil in the
commonlyemployed to circulate the refrigerant
rich'solventfrom’the absorber through the heat
exchangers against the pressure in the separating
can then perform its ‘normal function. This
would cause a slight decrease in the e?iciency,
but it would be‘ only a fraction of the loss caused
means. To cause such av circulation requires that
thepump impress upon the refrigerant rich liquid
It is also apparent that this solvent
by using vapor which contained considerable re
frigerant and .would of course ‘be operatively
much cheaper than an externally energized pump,
as in general heat energy is the cheapest avail
No details of the proposed pump are included
from the absorber a pressure substantially greater
than‘ the pressure in the separating'means'. This
pump is driven by external energy, such as an
electrically operated motor. Such a pump, how
ever, has the disadvantage of complex packing
glands which may leak-and also it requires high 35 as it is obvious that a common pump of the
double piston, duplex boiler feed type would op
grade energy to drive it. There is much to be
erate and that numerous developments of this
gained in making the machine self -contained and
type and the diaphragm types could be used.
independentof this external-source of energy.
Thus the novelty does not reside in the pump
This is done in somemachines by the introduc
tion of a third ‘fluid to balance the pressure
but in the means employed in supplying energy
throughout, the refrigerant expanding and'con
densing due ‘to differences in partial pressure. In
other machines automatic valve systems operate
at intervals toequalize-thepressure in part of
the system, thus allowinganaccumulation of
the refrigerantrich solvent to ?owby gravity
There follows,v a list of refrigerant-solvent com
binations which not only meet the requirements
speci?ed above, but which are individually new
in themselves, and have been moreover chosen
to represent combinations highly useful from the
practical standpoints of temperatures and pres
into-the separating means. Three ?uid machines
have not, as yet, proven very e?icient and ma
sures involved and chemical stability. There is
given for-each combination the difference in boil
ing points, the condenser and evaporator pres
sures, maximum boiler temperatures, and theo
retical minimum energy ratios (ratio of total
heat input to total useful refrigerating effect,
both in. heat units, vallowingia.20% stack loss in
chines with equalizers lose due to wasted refrig
erant. richvapor for pressure equalizing.
1' Wepropose to, utilize a pump which is ener
gized-by vapor fromthe separating means and
which operates. whenever a quantity of refrig
erantrich solvent liquor from the absorber has
accumulated. lfl‘hiseliminates the necessity of 55 heat input to boiler).
Table I
° F.
Freon 12, C012]?
Carrene, CHaCli..__ Freon 113, CzClgF;
.- D-48, CzHzClzw,
Methyl chloride, CHgCl. Carlene, CHzClz...
6.. ________________ __
__do ________________ _.
Freon 114, CCl2F4.__
..(l0 _____ __
o _____ __
° F.
° F.
° F.
-—21. 7
—.21. 7
139. 7139.7
l. 85
2. 30
114. 7
Freon 113, CzChF: .... __
1. 73
V 91
5. 65
74. 7
~ 91.3
_ ,
8 ___________ ._do ________________ __
9. _
‘ 1BS1122
Bfgiit gm‘
1.: 100°
atmos. '1' atmos
“1 4°
C01. ............
_. Trichloro ethylene,
1. 72
13 _____ __ Freon 21, CHCIzF___._
CCh _____________ ._‘___._
14 __________ __do ________________ _. Trichloro ethylene,
16 _____ __
Ethyl chloride, CzH5C1.
C014 _________ h...‘ .... -.
17 __________ __do ________________ __ Trichloro
Freon 11, 00131?‘ ___________ "(10,. ______________ __
SO, ___________________ __
Acetone C3H6O _______ ._
' 154
. 22 __________ ________________ -.
Methylacetate, CzHaOz.
.14 ‘.
It is to be noted that those combinations shown
above which comprise for both refrigerant and
solvent halogenated hydro-carbons having fewer
may again bylsuitable means be taken up by the
solution from the absorber. It is understood that
heat may also be conserved at other points in the
than three hydrogen atoms and at least one
?uorine atom are particularly desirable for use
system where desirable and possible. The re
frigerant-rich gas is carried from the tower l9
by’ means of the pipe 29 to the condenser 30,
cooled-to condensation by the coil>3l or the sur;
rounding medium, and the arrow 32 indicates
heat out of the cycle. The liquid from the con-'
because of low toxicity and great chemical sta~
bility. Such compounds are in use as refriger
ants, but we propose to use them as well for sol
In the disclosure and claims of this applica 10 denser is piped to the evaporator H] by the pipe
33, in which there is interposed a flow controlling
tion, the terms 11-48 and D-60 refer, respectively,
means 34. The entry of the solvent into the
to the “trans” and “cis” forms of dichloroethyl
absorber is regulated by the ?ow ‘controlling
ene. They are known as such commercially'since
means 35.
their boiling points on the centigrade scale are,
The pump 36 may be a well known unequal
respectively, 48° and 60", although their chemical 15
area double-piston duplex pump which is actu
formulae are the same.
ated by solvent vapor through pipe 31 emitting
The manner of use of these novel combinations
may be seen by reference to the ?gures and .to I from the point 38 in the tower I9, which point is
between the fractionating section of the tower
the explanations thereof which follow,
In Figure 1 the evaporator 10 receives the liquid 20 and the liquid level in the still thereof. The
vapor passes from the pump 36 by the pipe 39 to
refrigerant, which evaporates at the low pres
the absorber. The pump 36 is adapted to utilize
sure, thereby absorbing heat from the medium to
the pressure difference prevailing between the
be cooled in coil H or from the surrounding me
point 38 and the absorber, and is of sufficient
dium. Arrow I2 indicates heat input to the cycle.
power to force the refrigerant-rich solution from
From the evaporator the gas is conducted by pipe
the absorber through the heat exchanger and
i3 to the absorber [4, which is of a suitable type _
into the fractionating tower, Check valves 2|’
with means , of introducing solvent therein
and 2! control the flow of the solution. It is evi
through the pipe l5 and the rose I6. In the ab
dent that there will be more than enough energy
sorber the refrigerant vapor is absorbed into the
solvent. A ?n tube coil I‘! represents means to 30 available to carry out the transfer of solution
from the absorber because the volume of solvent
remove the heat in the solvent and the heat pro
available as vapor can be many times the volume
duced by the absorption of the refrigerant into
of liquid solvent and refrigerant which must be
the solvent. Arrow l8 shows that at this point
returned to the tower l9. The solvent vapor is
heat is being taken out of the cycle.
exhausted from the pumping means into the ab
The solution is returned from the bottom of the
sorber in addition to the bulk of the solvent ar
absorber M to the fractionating tower [9 by
riving there directly in the liquid state.
means of the pipe 20, wherein there is-interposed
Figure 2 shows in diagrammatic form an ab
pumping means 36, which maybe an unequal
» sorption'refrigeration system, likewise adapted to
area, double diaphragm pump, An ordinary mo
tor driven pump may be substituted. The solu 40 the use of the combinations hereinbefore speci_
?ed as forming part of this invention, and in
tion passes through the heat exchanger 22,
which system an inert gas is used to obviate the
whereby there is effected a heat exchange be
necessity of a pumping means. In this system
tween the relatively pure solvent in pipe I5 and
the fractionating tower 40 operates precisely as
the refrigerant-rich solution in pipe 20. The
solution heated in this manner passesv into the b4. On in the systems shown in Figure 1, with the ex
ception that a vapor lift pump shown at 4|
fractionating tower H] at the point 23, which is
serves to lift the solvent through a riser 42 into
that point at which the liquid present in the frac
a standpipe 43, in order that sufficient head'may
tionating tower has approximately the same com
be supplied to cause the solvent to flow by gravity
position, or preferably composition and tempera
ture, as the solution from the absorber. Other 50 through the heat exchanger 44 into the absorber
45. The vapor used to perform the lift returns
points may be chosen, but are less effective. _
to the base of the tower just above the liquid
In the fractionating tower Hi there is mutual
level therein through the connecting tube 46. As
contact throughout the length of the fractionat
ing portion thereof between liquid passing down- _ in the previously described systems, the substan:
ward‘ and vapor passing upward, whereby the 55 tially pure refrigerant from the top of the tower
passes through the condenser 41, whence it
former becomes enriched in solvent and the latter
passes through liquid seal 48, into the evaporator
becomes enriched in refrigerant, Liquid for the
49, wherein evaporation takes place and the gase
upper portion of the tower is provided by the
ous refrigerant passes through the heat ex
partial condenser 24. Heat to the fractionating
tower is supplied by suitable means such as the 60 changer 50 into the absorber 45. From the point
at which refrigerant vapor commences to liquefy
burner 25, which heats the substantially pure
in the condenser to the liquid level in the ab
solvent which is in liquid form in the bottom of
sorber, there exists an inert gas, such as for ex
the tower l9.
ample, helium, the partial pressure of which is
It will be noted that the solution for the ab
sorber is drawn off from the bottom of the frac 65 everywhere equal to the difference between the
partial pressures of the refrigerant (plus that of
tionating tower and consists of substantially pure
the solvent) and the total pressure in the system.
solvent. At the same time the ef?ux from the top
The inert gas carried to the absorber by the ?ow
of the tower consists of substantially pure re
of refrigerant vapor thereto is returned to the
frigerant. The fractionating portion of the tower
I9 is packed with helices or Raschig rings, or the 70 top of the evaporator 49, circulation taking place
because of the difference in density between the
like, or may be provided with bubble plates.
refrigerant laden inert gas and the inert gas freed
These helices or equivalents are indicated by the
from refrigerant by the solvent in the absorber.
number 26.
A gas heat exchanger 50 serves to lower the tem
The arrow 28 indicates heat into the cycle and
arrow 2'! indicates heat out from the cycle, which 75 perature of the inert gas returning to the evapo
rator. An inert gas reservejl is. provided to com
.6. Theprocess ofabsorption refrigeration com
pensate for_pressure changes due to changes in
atmospheric temperature, and is connected to the
prisingcireulating arefrigerant through an evap
orator, absorbing the vaporized refrigerant in a
condenser at a point ahead of the liquid seal 48
solvent and vforming an enriched liquor, intro
in order that the latter may function as. such. IA ducing the enriched liquor into a fractionating
The refrigerant-laden solvent ?ows through. the
tower?and therein separating the refrigerant and
heat exchanger 44 by gravity into the fraction
ating tower at a point52, chosen as the optimum
in accordance with the principles hereinabove
set forth.
solvent by fractionation, passing liquid solvent
from the tower to the absorber in indirect heat
exchange with the enriched liquor, and separate
The following systems may be also used but
ly;passmg @0123!“ ‘2am; under glpfessure from
suffer from the disadvantage of too high a differ-ence in boiling point. In some cases they may
even be used without fractionation.
_sa>ld'tqwer ° 935°? er an? r V ng 3' pump‘
mg means TO!‘ the em‘lched llquor by Such Das
sage ofrlthe solvent vapor.
Table II
Diff. in
Max. boiler
° F.
4f _____ _.
Freon 12, 0012172., ____ -. ,D-60, C2H2Clz ________ ._
is ..... __
° F.
-° F. '
° r‘.
Freon 21, CHOhF _________ "310.". ______________ __
Ethyl chloride. cursor. _____do _______ ._
1. 75
12 ..... __ Freon 114,0;OhF4 ____ __ Pertbliloro ethylene,
20,___.,___‘. Freon l1, OChF____, _______ ________________ ._
We claim:
1. As a refrigerant-solvent combination for use
7. A process according to claim 6 wherein said
refrigerant and solvent differ in boiling points by
in absorption refrigeration systems, Freon 2'1 30 less than about 150° F,
(CHClzF) asthe refrigerantand Trichloro ethyl3_ A process according, to Claim 6 wherein Said
6116 (0211013) as the Solvent}
refrigerant and solvent are halogenated hydro
2- A Process of absorptlon l'e?'lgeratmn com‘
prising vaporizing Freon 21 (CIiClzF), absorb-
mg Said Freon '21 (CHCIZF) .by tnchloroethylerte 35
carbons and differ in boiling points by less than
about 150° F.
9. An absorption refrigerating apparatus com
(CzHCla), and separating said Freon 2'1 and mprising, in combination, an evaporator, an ab
chloroethyletle by fractlonaplon' .
sorber connected to receive refrigerant therefrom,
A machme for absorptlon refngera'tmn “ima fractionating tower, means including a conduit
pnsmg an evaporator’ .an akF-Sm'bM’ a’ Separatmg
and a pump for delivering solvent and absorbed
means empmymg fractmnanon' apd 3’ charge of 40 refrigerant from the absorber to the tower, means
Freonl 2i (CHChF) and‘ tncmoroethylene
for‘ ‘actuating said pump comprising a conduit
(CZHC 3)‘
communicating with the fractionating tower ad
The Proms? of absorptionrefngelmtxon com"
jacent thelower end thereof and adapted to de
pnsmg clrculatmg Freon 2'1 (CI-I012?) through
liver solvent vapor under pressure from the tower
an evaporator.and to {m absorber’ abs-orpltlg the 45 to the absorber, a conduit delivering solvent from
vaporized refngera’nt m a’ Solvent. conslstmg of
the tower to the absorber means for producing
t.n°h1°r°ethy1en.e (CFHCISL pumpmg the? s01“?
indirect heat exchange "between the solvent
tlolifto 1'1 fragttonatmg towel!" aim ther'eln sep'
am mg t e re ngerant and §0 ven '.
travelling in said conduit from the tower and the
solvent and refrigerant travelling in the conduit
The pmfiis of absorptlon refngemtlon com‘ 5" from the absorber to the tower, a condenser, and
prlslng vapol'lzmg Freqn 21 (CHCIZF) and ab‘
means for delivering refrigerant from the upper
sorbing the same by trichloroethylene (CZHCIs),
end of the tower to the condenser and from the
separating the aforesaid refrigerant and absorbéon'denser to the evaporator.
ent by fractionation, condensing and cooling. said
refrigerant, and utilizing the separated andcon- 55
densed refrigerant vapor for. extractingheat from
a refrigerable material.
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