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Патент USA US2122361

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June 28, 1938.
Filed Feb. 6, 1937
3 Sheets-Sheet 1
| I
June 28, 1938.
Filed_ Feb. 6, 1937
3 Sheets-Sheet 2
June 28, (1938‘.
Filed Feb. 6, 1937
3 Sheets-Sheet 3
A670 24, W
Patented June 28, 1938
1 Hugo M. Ullstrand, Evansville, Ind., assignor tov
Servel, Inc., New York, N. Y., a corporation of
Application February 6, 1937, Serial No. 124,354
4 Claims.
(01. 62-95)
My invention relates to refrigeration, and
erator. V, A suitable combustible gas is delivered
more particularly to evaporators or cooling units
from a source of supply through conduit i9 to
the burner I1, and the ?ow of gas to the lat
ter may be controlled by a control valve 20 which
for refrigeration apparatus.
In refrigerators, particularly of the househol
5 type, the evaporator or cooling unit is arranged
is connected by a tube 2i to a thermal bulb or
element 22 secured to and in thermal contact
with the cooling unit Ill.
The heat applied to the generator ll causes
‘space at a desired low temperature for properly ammonia vapor and absorption liquid to pass
through an opening 23 at the lower end of a 10
preserving foods.
It is an object of my invention to provide an 'conduit 24 which constitutes a vapor-lift and
evaporator or cooling unit which will eifectively conducts ammonia vapor and absorption liquid
conduct heat from trays adapted to contain into the'upper part of a stand-pipe or separa
tor 25. The liberated ammonia vapor entering
water to be frozen and will also present an em
the stand-pipe 25 ?ows downward through a 15
cient heat transfer surface for cooling air flow
ing in contact therewith. I accomplish this by ' vertical conduit 26 into the analyzer l6 and, to
providing a metallic bodyv which is so formed that gether with the ammonia expelled from solution
the heat conductive path between a part utilized ‘in the generator ll, ?ows upward to an air
for cooling air in a storage space and a part em
cooled condenser 28. The ammonia is lique?ed
ployed for freezing is su?iciently small so that a in the condenser 28 and flows through a con- 20
temperature differential is maintained between duit 30 and conduit 55-into the upper section of
these parts which will insure maximum thermal the cooling unit lll which is arranged in a ther
efficiency of the cooling unit.
mally insulated storage space 3|.
The above and other objects and advantages of
An inert gas, such as hydrogen, enters the low
this invention will become apparent from the er section of the cooling unit it! through a eon- - 25
in a thermally insulated storage space and pro
vides refrigeration both for making ice cubes
and the like and for maintaining the 'air in the
following description taken in conjunction with
the accompanying drawings of which Fig. 1 dia
grammatically illustrates refrigeration appara
tus provided with a cooling unit or evaporator
duit 51 from the outer passage 32 of a gas heat
exchanger 33. The liquid ammonia evaporates
and diifuses into the hydrogen with consequent
absorption of heat from the cooling unit In and
30 embodying the invention; Fig. 2 is a top plan
its surroundings. The resulting mixture of am- 30
monia and hydrogen, that is, gas rich in am
is a vertical sectional view taken on lines 3-3 'monia, ?ows downward from the upper section
of Figs. 2 and 5 respectively; Fig. 4 is a sec
of the cooling unit Ill through conduit 55 and
tional view taken on line 4-4 of Fig. 3; Fig. 5 the inner passage or conduit 34 of the gas heat
is a front perspective view of the cooling unit exchanger 33 which is connected at its lower end 35
shown in Figs. 1 and 2; and Fig. 6 is a vertical to the upper partof a vessel 35. The gas rich
sectional view taken on line 6-6 of Fig. 3.
in ammonia ?ows from the vessel 35 into the .
Referring to Fig. 1, I have shown my improved lower end of an air-cooled absorber 33 in which
cooling unit or evaporator ill in connection with i the ammonia is absorbed into weak absorption
view of the cooling unit shown in Fig. 1; Fig. 3
refrigeration apparatus of a uniform pressure
absorption type and like that described in ap
plication Serial No. 53,376 of H. M. Ullstrand
and A. R. Thomas, ?ied December 7, 1935. The
refrigeration apparatus comprises a generator
45 ll having a partition I! provided with an open
ing I3 to provide communication between a for
liquid that enters the upper part of the absorber 40
ward chamber l4 and a rear chamber l5 which
is connected to an analyzer vessel It. The gen
erator ll contains a body of absorption liquid,
50 such as water, having a suitable refrigerant,
The absorption liquid flowing downward
through the absorber 36 becomes enriched in
ammonia and ?ows into the vessel 35 and thence
such as ammonia, in solution therein.
The generator ll may be heated in any suit
able manner, as by a gas burner ll, which pro
jects its ?ame into the forward end of a hori
55 zontal flue l8 which extends through the ‘gen
through a vertically extending conduit 31. The
hydrogen, which is practically insoluble and
weak in ammonia, flows upward from the ab
sorber 36 through a conduit 38 and the outer
passage 32 of the gas heat exchanger 33 into the 45
lower section of the cooling unit Ill.
through the outer passage 40 of a liquid heat ex- 50
changer and the analyzer l6 into chamber i5
of the generator ll. Liberated ammonia vapor
and absorption liquid are caused to' flow upward
through the vertical conduit 24 into the upper
part of the stand-pipe 25 to a higher level than /
it is in the absorber 36, and the absorption liquid
weak in ammonia flows from the stand-pipe 25
through the inner passage or conduit 4| of the
ment, the top wall 46 of the cooling unit is formed
with a plurality of spaced upward extending‘
cooling ?ns 69 of the general shape shown in
liquid heat exchanger and conduit 31 into the . Figs. 5 and 6. The uppermost loop 5| of the
conduit 45, which is located at the top wall 46,
upper end of the absorber 36.
The lower end of the condenser 28 is connect
ed by a conduit 42, vessel 43, and conduit 44 to
the gas circuit, so that any hydrogen which may
pass through the condenser can ?ow to the gas
,10 circuit and not be trapped in the condenser. If
ammonia is not lique?ed in the condenser‘ due to
an increase in air temperature, the ammonia
vapor will ?ow through conduit 42 to displace
is utilized to cool the top wall and the ?ns formed
integrally therewith, whereby air circulating over
these surfaces is cooled and maintained at a de
sired low temperature.
It will now be understood that the upper part
of the cooling unit is primarily utilized for cool
ing air in the storage compartment and that the
hydrogen in the vessel 43 and force hydrogen
15 through conduit 44 into the gas circuit,vthereby
remaining or lower part is employed to provide
refrigeration formaking ice cubes and the like.
The air in the storage compartment is preferably
raising the total pressure in the system so that
maintained at a desired low temperature which
an adequate condensing pressure is obtained for
is above freezing while trays containing water
the increased air temperature.
or the like positioned in the cooling unit must
be cooled to a temperature which is below freez
In accordance with this invention, the evapo
20 rator or cooling unit l9 comprises a looped coil
or conduit 45 which is arranged in good ther
mal relationwith a metallic body having a‘ top
wall 46, bottom wall 41, side walls 48, and spaced
shelves 49 and 50 extending between the side
The coil 45 is formed to provide a plu
rality of U-shaped loops 5|, one of which is
shown in Fig. 4, the loops being disposed one
above the other with the closed ends of the loops
at the forward end of the cooling unit III.
In order to effect efficient heat transfer be
tween the metallic body and the coil 45, the
-walls and shelves are cast about the loops 5|
with the loops positioned at the under sides of
the top and bottom walls 46 and 41 and the
35 shelves 49_and 56. As shown most clearly in~
25 walls 48.
Figs. 3 and 6, the sides of the loops 5| extend
along the side walls 48 and the closed ends extend >
ing. Since the upper part of the cooling unit I9 20
is formed with cooling fins to provide an exten
sive heat transfer surface, the temperature of the
uppermost loop of the conduit 45 will be higher
than the temperature of the other loops 5| lo
cated at the shelves 49 and 50 and bottom wall 25
41. With the loopr5| located at the shelf 49 at a
lower temperature than the uppermost loop 5|,
the ability of the loop 5| at the shelf 49 to pro
duce refrigeration for making ice cubes and the
like is impaired in that this loop of the conduit 30'
45'tends to elTect removal of heat from the cool
ing ?ns 60 and the top wall 46.
In order that as great a temperature differen
tial as possible will be maintained between the
loops 5| located at the shelf 49 and the top wall 35
46, the side walls 48 are formed with elongated
slots or openings 6| which. are parallel to the
across the forward open end of the cooling unit shelf 49 and at a region forming a boundary be
Ill. The bends 52 between successive loops 5| . tween the latter and the, top wall 46. By pro
are formed on opposite side walls 48 which ex
viding the slots 6| the heat conductive path be
tend or project beyond the rear of the top and tween the shelf 49 and top wall 46 is reduced con
bottom walls 46 and 41 and the shelves 49 and siderably, whereby the loop 5| located at the
59. The projected side walls 48 are cast about shelf 49 effects less withdrawal, of heat from the
half the circumference of the conduit 45 at the upper part of the cooling unit "I. In this man
bends 52, as shown at 53 in Fig. 4.
ner the loop 5| at the shelf 49 is maintained at a
The upper .end 54 of the pipe 45 is adapted lower temperature and the removal of heat from 45
to be connected to the conduit 55 which is con
a tray positioned thereon is effected more rapidly
nected at its other end to the inner passage 34
to hasten the production of ice cubes and the
of the gas heat exchanger 33, and the lower end like.’ Not only is the temperature of the loop 5|
56 thereof is adapted to be connected to the con
at the shelf 49 maintained at- a lower. tempera
duit 51 which is connected at its other end to ture by providing the slots 6|, but the tempera 50
the outer passage 32 of the gas heat exchanger.
ture of the cooling ?ns 60 and top wall 46 is
The under side of the bottom wall 41 of the cool
such that air circulating in the storage space is
ing unit is provided with a sleeve 58 having an maintained at a desired value above the freezing
opening to receive the thermal bulb 22 of the
temperature. It will therefore be understood 55
expansible ?uid thermostat.
that by making the heat conductive path suffi
The shelves 49 and 50 and the bottom ‘wall 41 ciently small between the part of the cooling unit .
are adapted to receive trays containing water utilized primarily for cooling air and the part
to be frozen. The evaporation and diffusion of employed for producing ice cubes and the like,
ammonia into the hydrogen within the conduit a higher temperature differential is maintained
45 takes place with consequent absorption of heat between these parts than would otherwise ob
from its surroundings, as explained above. When tain, and the thermal efficiency of the cooling
the trays are positioned in the cooling unit, _ unit is improved.
therefore, heat is removed from the bottom of
While a particular embodiment of the inven
the trays through the shelves 49 and 59 and tion has been shown and described, such varia 65
-bottom wall 41 which are in thermal relation tions and modi?cations are contemplated as fall
with conduit 45. The shelves‘ 49 and 50 and the within the true spirit and scope of the inven
tion, as pointed out in the following claims.
bottom wall 41 are provided with central open
I claim:
ings 59 to permit water to drain therefrom when
1.’An evaporator comprising a coil having a 70
the cooling unit In is being defrosted. A tray or
pan (not shown) may be arranged below the plurality of spaced loops disposed one above the
cooling unit to collect water formed during such other, a metallic body having top, bottom and
defrosting periods.
side walls, and shelves extending between said
In order to provide an extensive heat transfer side walls, a plurality of ?ns extending vertical
75 surface for cooling air in the storage compart
1y upward from said top wall, said body being 76
cast about said coil so that said loops are located
at said top wall and said shelves, at least one
of said side walls having horizontally elongated
opening between said top wall and the uppermost
shelf directly beneath said top wall to reduce the
heat conductive path between said top wall and
said loop located at said uppermost shelf.
parts to reduce the heat conductive path there
3. A cooling element as set forth in claim 2 in
which said casing is formed by casting metal and
the refrigerator passages are formed by a coil
cast as an insert.
4. In a cooling element for a refrigerator, a
metal casing having side walls and forming a
freezing compartment for ice trays or the like,
said side walls having openings suitably located 10
and of su?icient size to materially reduce the heat
forming a freezing compartment for ice trays conductive path between the upper and lower
or the like, the upper part of said casing hav
parts of-said casing, one of said parts having a
ing more extensive heat transfer surface for cool
greater extent of heat transfer surface for cool
1.5 ing air than the lower part, and openings in said I ing air than‘the other part.
side walls intermediate said upper and lower
2. A cooling element for a refrigerator com
prising a unitary metal casing containing re
10 frigerant passages and having side walls and
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