U.S. patent number 3,866,435 [Application Number 05/366,279] was granted by the patent office on 1975-02-18 for cooling container.
This patent grant is currently assigned to Firma Burger Eisenwerke Aktiengesellschaft. Invention is credited to Karl Frank, Martin A. Frank, Dieter Tschentscher.
United States Patent |
3,866,435 |
Frank , et al. |
February 18, 1975 |
COOLING CONTAINER
Abstract
A transportable refrigerating container including descending
passage means operable to receive a gravity induced flow of coolant
gas and having flow controlling aperture means providing
individualized, controlled communication between the descending
passage means and individual product compartments.
Inventors: |
Frank; Karl (Linz/Rhine,
DT), Frank; Martin A. (Cologne, DT),
Tschentscher; Dieter (Mayen, DT) |
Assignee: |
Firma Burger Eisenwerke
Aktiengesellschaft (Burg/Dillkreis, DT)
|
Family
ID: |
5846866 |
Appl.
No.: |
05/366,279 |
Filed: |
June 4, 1973 |
Foreign Application Priority Data
Current U.S.
Class: |
62/382; 62/420;
62/457.1; 62/388; 62/441 |
Current CPC
Class: |
F25D
17/04 (20130101); F25D 3/125 (20130101) |
Current International
Class: |
F25D
3/00 (20060101); F25D 17/04 (20060101); F25D
3/12 (20060101); F25d 025/02 () |
Field of
Search: |
;62/384,388,382,457,419,420,440,441,443 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Perlin; Meyer
Assistant Examiner: Capossela; Ronald C.
Attorney, Agent or Firm: Burns, Doane, Swecker &
Mathis
Claims
1. In a transportable cooling container adapted to keep
temperature-sensitive products, such as food and pharmaceuticals,
cool during transportation thereof and having
a work space subdivided into several vertically spaced product
compartments for the cooled products including an uppermost product
compartment
a coolant compartment disposed above said product compartments,
there being a tendency during transportation of said container for
the compartments to become progressively warmer relative to a
downward direction of reference;
the improvement comprising:
at least one passage means descending from the coolant compartment
and adapted to receive a gravity flow of gasified coolant; and
a plurality of vertically spaced apertures branching from the
descending passage means and individually communicating with
individual ones of said product compartments;
the sizes of the inlet mouths of said apertures increase
progressively relative to a downward direction of reference such
that said apertures divide said gravity flow of gasified coolant
into increasingly larger portions relative to a downward direction
of reference, to maintain the
2. A cooling container as described in claim 1 wherein:
an upright baffle plate is located at an upper portion of said
descending passage means and is operable to provide a constricted
entrance into the
3. A cooling container as described in claim 1 wherein:
said descending passage means, at its lower end, and at a location
shielded
4. A cooling container as described in claim 1 wherein:
5. Apparatus according to claim 1 wherein said transportable
cooling container has support wheels, side walls, and front and
rear ends spaced in the direction of container travel; said passage
means extending laterally across and vertically along said rear
end; at least part of said coolant compartment being inclined
relative to horizontal toward said descending passage means to
facilitate gravitational flow of coolant gas thereto; the apertures
disposed beneath the uppermost product compartment including guide
tongues extending outwardly and upwardly from their respective
compartments and into said descending passage means; the horizontal
locations of said tongue-including apertures being generally
staggered relative to a vertical direction of reference to minimize
the extent to which the flow of cooling gas into said apertures is
impeded.
6. A cooling container as described in claim 1 wherein:
said descending passage means extends essentially over the entire
height of the container and reaches across one side of the
container;
said descending passage means is bounded on one side by an outside
wall means of the container and on another side by a separating
wall means extending essentially parallel to the outside wall
means; and
said separating wall means has sluice-like apertures, each leading
to an
7. A cooling container as described in claim 6, wherein:
said sluice-like apertures comprise openings in the separating wall
means and guide tongues extending from individual apertures and
projecting from the separating wall means into the descending
passage means at progressively greater angles of inclination along
a downward direction of
8. A cooling container as described in claim 7, wherein:
said container includes a door, located on a narrow side of said
container; said door being operable relative to said
compartments;
said descending passage means is disposed on a side of said
container opposite said door; and said descending passage means is
disposed in communicating relation with vent means communicating
with the exterior of
9. A cooling container as described in claim 8, wherein:
said coolant compartment supports a coolant inclined in relation to
the horizontal in such a way that it slopes downward toward said
descending
10. A cooling container as described in claim 9, wherein the entire
container, including said coolant and product compartments, has a
downward
11. A cooling container as described in claim 1 wherein:
said descending passage means comprise shaft means provided on
opposite ends of the container; and
at least an upper one of said product compartments includes vent
means communicating with the exterior of said container and located
on sides of
12. A cooling container as in claim 11, wherein:
said coolant compartment supports coolant inclined downwardly
toward respective ones of said shaft means to facilitate
gravitational flow of
13. A cooling container as described in claim 12, wherein:
each of said shaft means is defined, at least in part, by spaced
wall means
14. A cooling container as described in claim 1 wherein:
an aperture communicating with the uppermost product compartment
may be selectively closed; and
said uppermost product compartment is operable to be selectively
vented to
15. A cooling container as described in claim 14, wherein:
said container includes an insulating plate disposed between said
uppermost
16. A cooling container as described in claim 1 including:
movable closure means for said apertures located beneath the
uppermost product compartment; coolant flow control means operable
to operate said closure means to control flow of gasified coolant
through said apertures in response to the temperatures of the
respective product compartment
17. A cooling container as described in claim 16, wherein:
a plurality of said closure means are interconnected such that said
coolant flow control means is operable to simultaneously control
the flow of gasified coolant through said plurality of said
apertures.
Description
GENERAL BACKGROUND, OBJECTS, AND
SUMMARY OF INVENTION
The invention relates to a refrigerating container to keep
temperature sensitive products, such as food, pharmaceuticals,
chemical products, etc., fresh and cool. Particularly, the
invention relates to a transportable container having a work space
subdivided in several chambers to receive the goods to be
refrigerated and a compartment for a gasifying coolant, especially
CO.sub.2 in solid form (dry ice). Preferably, this latter
compartment is located above said work space.
For keeping temperature sensitive products cool and fresh, movable
containers are used today in which the cooling system consists of
added consumable coolants. Beside nitrogen and freon, carbon
dioxide especially comes into consideration as a consumable coolant
here. In gaseous form, carbon dioxide is heavier than air and in
solid form at standard atmosphere pressure, in its own gaseous
atmosphere has a temperature of -78.5.degree.C. This solid
CO.sub.2, called dry ice, sublimates, i.e., it passes from a solid
to a gaseous state, whereby at atmospheric pressure with the gas
heating to 0.degree.C of the neighborhood, 152.4 K. cal/kg are
withdrawn.
Heretofore, this coolant is placed in the container, in the case of
the known containers of the initially mentioned construction, in
the form of prismatic slabs (plates) together with the material to
be cooled, or it is arranged compactly above or beside the work
space. This, however, results in the essential disadvantage that
the cooling stream of gas fills the work space in an uncontrolled
manner and that the temperature pattern developing in the work
space is very uneven, in such a way that at certain places very low
temperatures prevail, with the consequence of local freezing of the
chilled goods, while at other places no sufficient cooling is
assured. These disadvantageous effects occur at an increased
degree, when using containers in air traffic, especially during the
starting and landing phases of the airplanes which cause
considerable inclinations of the containers.
To this it must be added that, particularly in air traffic, very
variable ambient conditions may occur. In case of a modern airport
with cold storage, the required quantity of dry ice is added to the
filled container which is at a temperature of
12.degree.-16.degree.C upon leaving the cold storage. The quantity
of coolant is here dimensioned such that the chilled goods remain
chilled until served on the airplane. If, however, there is no cold
storage at the airport, then such a quantity of dry ice must be
added to the container after it being filled, such that the dry ice
will be capable of cooling down the container itself and its
contents from ambient temperature to, for example, cold storage
temperature and to maintain this temperature of
12.degree.-16.degree.C until time for serving. From these variable
possibilities of use and requirements there result, however,
variable refrigerating problems, with which the customary
containers cannot cope.
It is the task of the invention, therefore to create a cooling
container of the initially mentioned type, in which the cooling
stream of gas flows controlled in such a way, that the temperature
field pattern in the work space of the container will be as even as
possible, even under unfavorable circumstances, as the beginning of
cooling, repeated opening of the container door, tipping and
sloping movements of the container,etc.
A further task of the invention consists in creating a container
which will cope with the stated variable condition, whereby the
degree of filling of the container with chilled goods and possibly
also requirements of the chilled goods for variable cooling needs
are still superposed as additional conditions.
According to the invention the solutio of these problems is
characterized by at least one descending shaft (passage means)
branching off from the coolant space, for receiving the developing
cooling gas, and from which shaft openings (i.e., apertures),
dividing the stream of cooling gas doseably or in segments into
partial streams, branch off into the individual work space
compartments.
In the invention one will insure that the cooling stream drops down
in a defined direction of flow in the descending shaft by the
action of gravity, whereby a partial stream is branched off for
each compartment having chilled goods and which can be dosed
exactly with a branch stream or segment which is adequate with
respect to its cooling performance. Detailed experiments have shown
that in this manner an even temperature field pattern quickly
occurs in the container which is essentially independent of outside
influences such as inclinations of the container during take-off of
the plane in which the container is located. Beyond that, however,
there also is the possibility, if desired, to produce temperature
field patterns which are even within themselves but variable among
each other, for instance, whenever chilled goods with variable
cooling needs are placed in the container.
A further development of the invention concerns a cooling container
with inserts arranged in levels one above the other, the topmost
level serving for the coolant, especially in a movable container
for keeping food in airplanes fresh and cool. Such containers,
mostly called trolleys, are developed according to the invention in
such a way that the descending coolant gas shaft, preferably
extending over the entire height of the container and across one
side or end of the device, is limited by an outside wall of said
container and by a separating wall essentially parallel to the
former, whereby the separating wall has sluice-like openings
leading to the insertable levels of the work space.
If this container has only one door, then the descending shaft can
be disposed on the container side opposite to the door, and the gap
space between the door and insertable shelves can have escape
openings for excess air and/or cooling gas, possibly in the form of
leaks of the door hinges. In this way one will achieve a
particularly exact guidance of the streams of cooling gas and
especially the development of an even temperature field at the
beginning of cooling will be accelerated, at a time when the
container is still filled with air.
In order to ensure that the desired pattern or direction of flow,
even in case of greater inclinations of the container, the
insertions for the coolant can be slightly slanted toward the
horizontal in such a way that it slopes toward the inlet for the
descending shaft.
In the case of cooling containers with doors at two opposed sides,
the arrangement advantageously is made such that two descending
shafts are provided on opposed sides of the container and that at
least one of the gap spaces, located between the other two
container sides and the insertion levels or goods areas, has escape
apertures for excess air and/or cooling gases, possibly in the form
of leaks of the door hinges. Further, the descending cooling gas
shafts can also be disposed on both sides of the container, in
which case it will be particularly effective to develop the doors
on their sides with double walls, and to use the two walls of each
door as boundaries for the descending shaft. These containers with
descending shafts at opposed sides of the container are
particularly insensitive --with regard to the temperature field
pattern -- to inclinations and tippings of the container.
In order to facilitate the controlled, segmented flow or division
of the cooling gas stream into partial streams, the apertures in
the separating wall or walls can be designed in such a way that
they consist of perforations of the separating wall and of guide
tongues or baffles assigned to the individual apertures and
projecting from the separating wall into the descending coolant gas
shaft. Advantageously, the apertures will have widths of passage
which are variable among themselves, in such a way that the cross
section increases from the topmost to the lowest inserting shelf,
whereby the width of passage is determined by the cross section of
the aperture and/or the position of the tongue. With that one will
achieve that the cooling effect over the entire height of the
container will be as even as possible. Nevertheless, it will not be
possible to prevent completely, the phenomenon that in the topmost
shelf for chilled goods, which is adjacent to the insert with the
coolant, the temperature will drop lower, particularly during the
period of the start of cooling. This may be desirable in some
cases, perhaps whenever edible ice (ice cream) is to be stored in
the topmost level. Whenever the same temperature is always wanted
in the topmost insertion shelf as exists in the lower shelves below
it, then according to the invention, the aperture of the topmost
insertion shelf for chilled goods adjacent to the insert for
coolants, can be provided with a closing lid and this insertion
shelf can have closable apertures leading outside.
It has proved to be particularly effective whenever, in the case of
the cooling container according to the invention, dry ice in form
of a heap of dry ice tablets, little rods or cubes is used as
coolant. This form of the dry ice, as compared to the customary
solid dry ice slabs, has a considerably larger evaporation surface.
This is of particular importance especially for the above-mentioned
cooling containers in air traffic since, there, mostly only
relatively short cooling times are required.
In a further development of the invention, provision is made such
that two longitudinally extending walls of a container are
developed as guides for the cooling gas in the form, each time, of
several flat channels which are connected on the one hand with the
compartment for the coolant and on the other hand with the work
space compartments, located at various horizontal levels, whereby
the cross section of passage of the channels is proportional to
their length.
In case of this further development therefore, the stream of
cooling gas is divided in partial streams and is fed to the
individual work space compartment such that the inflowing quantity
of gas is largely independent of inclinations of the longitudinal
sides of the container, which are generally pointing in the
direction of flight. Since guidance of the cooling gas takes place
at both longitudinal sides, the stream of cooling gas must pass
through relatively short paths in order to fill the space between
two adjacent goods levels, - - i.e., the coolant space for one
goods area.
In order to adapt the cooling effect furthermore to the various
conditions on the airport, the insertion of the coolant is
developed especially according to the invention as hereinafter
described and claimed. Especially, insertion of the coolant is
subdivided into shelves, which house the quantity of coolant
required for the pertinent cooling task, whereby a heap of small
dry ice rods is used advantageously, since such a heap has a larger
surface than the dry ice slabs of the same weight and thus the
quantity of cooling gas sublimated in the unit of time is
larger.
DRAWINGS
In the drawings, embodiments of the invention are shown by way of
example, namely:
FIG. 1 shows a cooling container in longitudinal section; FIG. 2 is
a perspective, fragmentary view of a separating wall of the FIG. 1
container showing sluice openings;
FIG. 3 is an end view of a separating wall of the FIG. 1
container;
FIG. 4 shows a section through the separating wall of FIG. 3 as
provided with automatically adjustable guide tongues;
FIG. 5 is a longitudinal section up to the axis of symmetry M/N, or
transverse median plane, through a prior art coolant trolley of
customary design;
FIG. 6 is a half segment of a trolley, modified, as in the
invention, with FIG. 6 being a view showing a section plane AB
oriented in a perpendicular plane and extending along the
longitudinal axis;
FIG. 7 shows the plane AB from FIG. 6, with half a side wall
exposed;
FIG. 8 shows, in a section format, the arrangement of the cooling
insert with the guidance of the cold stream as incorporated in the
trolley of FIG. 6;
FIG. 9 is an internal elevation view of the cooling gas channels in
the side wall of the trolley of FIG. 6;
FIG. 9A is a transverse sectional view of the cooling gas channels
depicted in FIG. 9;
FIG. 10 is a fragmentary top plane view of the cooling insert of
the FIG. 6 trolley provided with transverse divisions or
longitudinally spaced functional coolant zones;
FIG. 11 is a fragmentary, further enlarged view of FIG. 10, showing
the cooling insert with details;
Fig. 11a is a sectional view taken along the plane CD in FIG.
11;
Fig. 11b is a sectional view taken along the plane E-F in FIG. 11A;
and
FIG. 12 shows a special embodiment of a layer for absorbing the
condensate and additionally insulating the inside space against the
cooling insert.
DETAILED DESCRIPTION
In the embodiment shown in FIGS. 1 to 4, we are dealing with a
so-called trolley, therefore a mobile container for prepared food,
as used in airplanes. Here the requirements for cooling performance
are particularly high, because within a limited time, and in
consideration of the least possible weight of the device itself and
its charge of coolants, a heterogeneous combination of foods as to
quantity and type must be kept cool in an environment mostly of
24.degree.C., with the entire system being also subject to
movements, for example, at starting of the plane.
FIG. 1 shows such a container in longitudinal section, in which the
chilled goods 12 are kept on parallel flat shelves 11 and the dry
ice 14 is disposed on the topmost shelf 13, the cooling insert. A
door is located in this container at its left end, as viewed in
FIG. 1. This cooling insert is connected on one narrow side or end
of the container by means of a gap 15 with the work space of the
shelves, in a manner yet to be described.
For thermal screening of the work or goods space against the
cooling insert 13, an insulating plate (board) 16 has been
provided, which does not impede the gap 15. Another insulating
plate 17 curbs the heat transfer of the environment through the
covering surface 18 of the container.
In order to guide the cooling stream, the entire container
(including shelf 13) in this example has been inclined relative to
the horizontal by about 2.degree., so that the cold CO.sub.2 gas
developing in the cooling insert 13 will reach the gap 15 on
account of its specific gravity being 1.5 times greater than that
of the air still in the work space. This inclination of the entire
container is possible in case of the selected embodiment, since the
contents to be cooled are not liquid in open bins (containers).
Naturally the same effect could also be achieved by the fact that
only the cooling insert has such an inclination, the chilled good
inserts on the other hand being disposed horizontally.
A gate slit 25 is located at one end of shelf 13 and is followed by
a descending shaft 21. Shaft 21 is defined by the narrow side
(i.e., end) wall 19 of the device and a separating wall 20,
parallel thereto. The cold stream in shaft 21 sinks to the bottom
because of gravity. This cold descending stream can emerge from the
shaft 21 through sluice-like apertures 22 which communicate with
the work space between the shelves.
These sluice openings consist, according to FIG. 2, of perforations
of the separating wall 20 and of guide tongues 23. These tongues
are shown in case of the FIG. 2 embodiment simply by a rectangle
constituted by three cuts and a bent edge, each tongue being bent
into the inside of the descending shaft 21 and facing upwardly in
an inclined or "baffle" manner.
Naturally other geometric forms are also possible for the guide
tongues, and their position in the descending shaft 21 can be flat
or arched. It has furthermore been recognized that the descending
shaft 21, at its lowest point, may be connected by apertures (which
are not shown in the drawing) with the work space, so that
condensate can emerge into the latter.
According to FIG. 1 and FIG. 3, these sluice apertures, except for
the opening of the insert of the topmost chilled goods shelf which
is connected with the descending shaft 21 by way of a slit 24, are
provided for each of the chilled goods shelves, in such a manner
that the effective width of passage means for emergency of the
partial cooling stream into the shelves becomes larger with growing
distance of the shelves from gap 15. The projection of the aperture
in the direction of the cooling stream is to be understood here as
the width of passage. This width of passage is here defined
therefore by the effective size of the "mouth" of flow capacity of
each such passage in chute 15 as governed by width and/or height of
the guide tongue and the bending angle .alpha. in FIG. 2.
Preferably the arrangement of FIG. 3 is to be selected, in which
the sluice apertures 23 are disposed, displaced in the direction of
the cooling stream and, as can be recognized, the opening angle
.alpha. grows with the distance from the gap 25 and with it the
above-mentioned width of passage. The increase in the size of the
opening angle, in addition to increasing passage "mouth" size,
tends to minimize the extent to which upper baffles 23 might
"shield" lower baffles 23 and impede flow into their associated
passages.
It is furthermore essential that the baffle plate which constitutes
the slit 25, and which runs across the entire width, screen the
slit 24, which represents the connection of the uppermost shelf for
chilled goods with the descending shaft 12. The reason for this is
to avoid a too severe drop of temperature in the topmost cooling
shelf. For the same purpose, bores or vents 26 are provided in the
topmost cooling shelf, which lead into the open.
Each of the aperture means 24 and vent means 26 may be provided
with selectively manipulatable closure means operable to
selectively open (partially or fully) or close these openings.
The cooling container as in the invention can be filled in the
customary cooling space at, for example, 6.degree.C. with food
dishes of this temperature, and then be charged with dry ice and
put to use. By the inclination of the container or the shelf 13, a
path leading by gravity into the descending shaft 21 and through
the sluice apertures 22 into the work space is forced upon the
heavy CO.sub.2 gas. After a relatively short time an even
temperature field pattern develops in the container, as a result of
the distribution of the sublimated dry ice according to the
invention. The required pressure balance or differential takes
place via the leaks in the doors of the container and through the
above-mentioned small bores 26 in the opposed long container walls
between cooling insert and uppermost chilled goods shelf. By the
arrangement of the bores 26 precisely at this spot, the most
endangered topmost chilled goods shelf will be protected against
freezing of the chilled goods.
It is apparent from FIG. 4 that, by the further development of the
invention, an automatic control for the closing of the cooling
stream by influencing the width of passage of the sluice openings
22 and thus of the partial cooling stream to the chilled goods
shelves can be provided. In this connection, a rod 27 is provided
which is connected on the one hand with the housing of the
container and on the other hand with one movable guide tongue or
baffle 30 and which moreover has a large temperature expansion
coefficient. This rod 27 deflects the tongue 30, which is connected
via a swivel joint or pivot connection 28 with the separating wall
20. The deflection is accomplished in such a way that in case of
too much cooling the rod 27 contracts and the effective cross
section or "mouth" size of passage of the sluice apertures is
decreased. In case of too little cooling, the rod expands and this
"mouth" size is enlarged. With the aid of the coupling rod means 29
it is possible to operate the sluice openings of several adjacent
levels in the manner of levers by a single adjusting rod 27.
Naturally, the embodiment shown can have numerous
modifications.
Thus, the invention can also be realized in case of containers with
two doors at the two narrow sides (ends), by making the latter with
double walls and by developing the inside walls of the doors as
separating walls with baffle plate 25 and sluice apertures 22. In
case of this embodiment, the function of the cooling stream depends
even less on the inclination of the container. At a precisely
horizontal position, the same quantity of cooling gas flows through
the two descending shafts running on each end, inside the doors,
and emerges through the sluice openings from both sides in the work
space. The inflow of the cooling gas into the descending shafts can
be facilitated still more by the coolant insert being buckled or
bent in such a way that it slopes on both ends toward the inlet
slits 25.
Furthermore, the invention is not only limited to the described
movable small containers, but it can also be used in case of
stationary large containers, perhaps the well-known container in
the so-called igloo construction. It is always essential in this
case, however, that the developing cooling gas is guided as a
homogeneous cooling stream with a definite direction of flow and
that it is then doseably distributed to the individual chilled
goods compartments.
For the explanations of the modifications of the invention
according to FIGS. 6 to 12, first of all, a trolley of customary
construction will be described on the basis of FIG. 5. In the FIG.
5 arrangement, the inside trolley space is divided in parallel
planes 110 for the reception of the chilled goods 111. Above the
topmost work plane is the cooling insert 112 with the dry ice 113.
The stream of cooling gas drops, in this case, through a slot 114
along the door, without guidance, downward whereby either the left
(or right) side is acted on more or less by the cooling gas as a
result of the inclination and thus an undesirable, variable cooling
is brought about at the sides of the door.
According to the invention the container now is developed according
to FIG. 6 in such a way that the stream of cooling gas is fed under
control inside the long side walls 115 to the spaces between the
planes 110 which are to be cooled. The arrangement of the channels
for controllably carrying the streams of cooling gas, according to
FIG. 7 as shown by cut AB made longitudinally of the trolley, with
the channels exposed to the right of exposure line VT, is made such
that, with due consideration of the flow resistance, the channels
leading to the lower planes, for example, 116 and 117, are
developed broader than those which supply the upper planes, for
example, 118, and that the broader channels are located on the
sides of the door. (i.e., the channels on the right side of line VT
would be a mirror image of the channel arrangement on the left
side.)
One example for the guidance of the cooling stream in the side wall
is shown in FIGS. 8, 9 and 9A.
The shaped side wall 115 (in sandwich type construction) has on its
inside the channels, for example, 116, 117, 118, already described.
In the inside wall 119, deep-drawn supports 120 for the planes 110
(inserts) have been developed. A part of at least some of these
supports has outlet slits 121 on their underside for the cooling
gas, and they are adapted in size to the width of the channel,
i.e., the wider the channel, the wider the slit associated
therewith. In the upper planes there are small discharge slits,
since there the cold radiation of the walls suffices for the
cooling. There also is an insulating layer 122 applied to the wall
in order to dam up or limit the cold radiation through the wall
itself.
For reinforcement of the walls 119 at about half the height, a
plane surface connected detachably with the wall elements 119, and
not shown, may be provided.
In order to make possible a thorough cleaning of the trolley, the
inside wall 119 can be removed.
The molded part 123, closing the trolley on top, houses the cooling
insert or drawer 124 in which is located the dry ice 113. In the
FIGS. 10 11, 11A, and 11B and via the cuts or sections CD and EF,
this cooling insert 124 is shown in detail.
FIG. 10 shows half the insert with its axes of symmetry P/Q
(longitudinal) and R/S (transverse). The loading surface for the
dry ice heap has been transversely divided by continuous transverse
strips 125 and discontinuous longitudinal strips 126 into partial
surfaces in such a way that, depending on the intended duration of
cooling, the entire space of the cooling insert or partial spaces
are filled with dry ice. The dry ice itself rests on a perforated
bottom 127 on which there are formed continuous strips 129. As
shown in FIG. 11, supporting rails 128 may support tray means 127.
Up to certain inclinations of the device, the strips on ribs 129
will prevent the heap of dry ice from slipping during the starting
phase of an airplane. The above-mentioned strips 129 thus serve as
holding and isolating strips and may be at least partly adjustable
and/or variable in height.
The connection of the cooling insert with the channels in the
lateral walls is accomplished by openings 130. Between each two
adjacent apertures there is each time a rail 128, which rail tends
to cause equal quantities of cooling gas to flow downwards through
all the openings 130 even at an inclination of the trolley, as
shown by lines X/X. The straight line Y/Y can be drawn just the
same, which refers to a dry ice retention slope as provided by
strips 125. The oblong holes 130 can be of different lengths, in
accordance with the width of their associated channels in the side
walls.
As this juncture, it will be recognized that the FIG. 6-11B
embodiment is a species of the FIG. 1-4 invention, with the space
between 124 and 127 providing a descending chute, branching off of
which are central apertures 116, 117, 118.
The insulation 31 (FIG. 8) located on the underside of the cooling
insert is of particular significance in order to prevent any
undercooling of the topmost shelf or of the highest shelves by too
great a degree of cold radiation through the base of the dry ice
container.
In the first cooling phase, the heavy cold CO.sub.2 gas presses the
air in the container upwards, and through leaks of the container
into the open air. Water vapor condenses from this air and is
deposited mainly on the insulating layer as a top limitation of the
space, and finally drips onto the chilled goods of the topmost
shelf and generally defaces their appearance and value. The
invention provides for an additional insulating plate 132 to be
attached below the insulating layer 131 firmly connected with the
molded piece 123, the raw material of said plate 132 being
permeable and permitting water vapor to pass through, but absorbing
droplets of fog and holds them, whereby the originally great heat
resistance of the raw material is reduced by the water absorption.
At the outset, the lowest layer of the insulation 132 with a
0.degree.C.-isotherm will constitute a "cold brake" or thermal
barrier. The increase of the heat conductivity of this layer with
the water absorption, which occurs during the cooling process in
its first phase (the sublimation temperature of the dry ice does
lie considerably lower in atmospheric air than a pure CO.sub. 2
atmosphere), serves to permit conductive cooling of the upper goods
compartment while avoiding thermal shock due to a too abrupt
cooling action at the outset. In other words, thermal shock due to
excessive conductive cooling through layer 132, at the outset, is
avoided, but such conductive cooling is gradually implemented as
the thermal conductivity of layer 132 increases.
This insulating layer 132 can be produced for example by a fabric
of plastic, for example, PVC, which after use in a container is
removed and dried and is removed after repeated use for hygienic
reasons.
A further embodiment of barrier 132 is shown in FIG. 12, where a
"bag" 134 of special cellulose which absorbs or binds water is
stretched across a resilient, U-shaped clip 133. A holding device
135 secures this assembly. The 134 bag is detached from clip 135
and thrown away after use and, since it consists of cellulose, is
simply burned.
According to this example the dry ice is housed in a sliding drawer
124 which, for the purpose of being charged, is pulled out of the
molded piece 123. In order to simplify the charging process, and in
order to use dosing aggregates for the quantities of dry ice
required for the cooling task, and in order to be able to
accomplish the charging in series or on the conveyor, the top
covering 135 may be developed as a tightly closing lid (not
permitting any admission of air), which is swivelably articulated
by a hinge 136.
If there is any desire to produce lower temperatures in the space
of the top level, for example, for the storage of ice cream, etc.,
then a direct gas connection to the cooling insert and to this
space must be established by one or more closeable and in one
dimension cntrollable apertures, possibly communicating with
channel means such as 118, but which are not shown.
SCOPE OF INVENTION
In describing the invention, its principal advantages have been
delineated and made apparent, and a variety of structural and
functional modifications have been noted.
Those skilled in the refrigerating art and familiar with this
disclosure may recognize other additions, deletions, substitutes,
or other modifications which would be deemed to fall within the
scope of the invention as set forth in the appended claims.
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