U.S. patent application number 11/728918 was filed with the patent office on 2008-01-17 for device for cooling food.
This patent application is currently assigned to SGL Carbon Aktiengesellschaft. Invention is credited to Gerrit Sonnenrein.
Application Number | 20080010999 11/728918 |
Document ID | / |
Family ID | 35500935 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080010999 |
Kind Code |
A1 |
Sonnenrein; Gerrit |
January 17, 2008 |
Device for cooling food
Abstract
An apparatus for cooling food, in particular water-based
beverages, includes a cold accumulator (6) that contains a phase
transition material. A conduit (8) for a water-based liquid that is
to be chilled is guided through the cold accumulator (6). Also
provided is a device (2) for dissipating heat from the cold
accumulator (6). In order to make such an apparatus less expensive,
easier to produce, and more effective, the cold accumulator (6) is
made from a composite material containing expanded graphite and a
phase transition material that undergoes a solid-liquid phase
transition at or above 273 K.
Inventors: |
Sonnenrein; Gerrit;
(Delbruck, DE) |
Correspondence
Address: |
LERNER GREENBERG STEMER LLP
P O BOX 2480
HOLLYWOOD
FL
33022-2480
US
|
Assignee: |
SGL Carbon
Aktiengesellschaft
|
Family ID: |
35500935 |
Appl. No.: |
11/728918 |
Filed: |
March 27, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/EP05/10379 |
Sep 26, 2005 |
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11728918 |
Mar 27, 2007 |
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Current U.S.
Class: |
62/3.64 |
Current CPC
Class: |
F25B 21/04 20130101;
F28D 20/023 20130101; Y02E 60/145 20130101; Y02E 60/147 20130101;
Y02E 60/14 20130101; F25D 2303/085 20130101; F25D 3/00 20130101;
F25D 31/002 20130101; C09K 5/066 20130101 |
Class at
Publication: |
062/003.64 |
International
Class: |
F25B 21/04 20060101
F25B021/04 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2004 |
DE |
10 2004 046 794.3 |
Mar 31, 2005 |
DE |
10 2005 014 742.9 |
Claims
1-12. (canceled)
13. An apparatus for cooling foods, comprising: a cold accumulator
containing expanded graphite and a phase change material configured
to pass through a solid-liquid phase change at or above 273 K; a
line for conducting a water-based liquid to be cooled through said
cold accumulator; and a device for removing heat from said cold
accumulator.
14. The apparatus according to claim 13, configured to cool
water-based beverages.
15. The apparatus according to claim 13, wherein said cold
accumulator contains a loose bed of graphite granules impregnated
with said phase change material.
16. The apparatus according to claim 13, wherein said phase change
material has a phase change temperature not above 10.degree. C.
17. The apparatus according to claim 13, wherein said phase change
material has phase change temperature above 0.degree. C. and not
above 10.degree. C.
18. The apparatus according to claim 13, wherein said device for
removing heat contains a Peltier element.
19. The apparatus according to claim 18, wherein said Peltier
element is connected to a reversible voltage supply and the liquid
flowing through said line is heatable for disinfection by reversing
a polarity of the voltage supply of said Peltier element.
20. The apparatus according to claim 13, wherein said device for
removing heat includes an absorber and/or evaporator refrigeration
unit.
21. The apparatus according to claim 13, configured as a cold
battery having at least one cold accumulator as a portable
unit.
22. The apparatus according to claim 21, wherein said portable unit
includes said device for removing heat.
23. The apparatus according to claim 13, wherein said line is
connected to a drink source and leads to a dispensing system.
24. The apparatus according to claim 13, wherein said line is
connectible to a central water supply.
25. The apparatus according to claim 13 configured as a cooling
container, which comprises a housing with an insulated wall and
said cold accumulator and said line integrated in said wall and/or
disposed in an interior of said housing.
Description
[0001] The invention relates to an apparatus for cooling foods, in
particular water-based drinks, which is described in the preamble
of claim 1.
[0002] Such an apparatus is disclosed by DE 198 56 214. In one
embodiment of the known apparatus, a cold accumulator is provided
in the form of an ice bank which is cooled via a coolant by the
cold side of a Peltier plate module. The drink to be cooled is
passed round or through the ice bank. The thermal conductivity of
the ice water and therefore the heat transfer properties of the ice
bank can be improved by distributing a good conductor, such as, for
example copper wool or copper pieces, in its volume. The cooling of
foods and drinks by ice is current practice, but has critical
disadvantages. A main disadvantage is the low thermal conductivity
of ice. The addition of copper material is firstly expensive and
secondly involves the risk that, for example, copper pieces, under
the influence of gravity, and with partial melting of the ice bank,
collect in the lower region and are depleted in the upper region. A
further disadvantage of ice which, however, has hitherto always
been accepted, is the unfavorable phase change temperature of ice
to water, with to date there always being the risk, which had to be
avoided by complex control technology, that also water-based drinks
froze. Although in this publication the use of a eutectic salt or
an aluminum block is mentioned as cold accumulator, the special
choice of the eutectic salt, in particular according to its
solid-liquid phase change temperature, is not described
however.
[0003] For industrial applications as tubular or plate heat
exchanger, EP 914 399 B1 discloses a composite material in which
pressed expanded graphite is impregnated with a phase change
material. The graphite acts as heat conductor which in addition is
able to take up the most varied phase change materials. As phase
change material, use can be made of paraffin, but preferably
likewise water/ice.
[0004] In industrial and commercial applications, generally use is
made of compression or absorption refrigeration units, the
relatively large dimensions of which and also high production
costs, oppose use in the domestic sector, however. For this reason,
for the provision of cooled drinking water in the lower price
segment, in particular in the field of small domestic units,
Peltier elements suggest themselves, in which, by applying an
electric field to two different electric conductors, one side heats
up and the other cools down.
[0005] Periodic provision of cooled drinking water for application
in the domestic sector, owing to the low thermal efficiencies of
Peltier elements, make effective storage of, for example during
night phases, a critical criterion for the capacity of a continuous
flow Peltier cooling.
[0006] The simplest form of such a cooling is disclosed, for
example, in DE 299 10 820, in which a closed water reservoir is
cooled down to the desired temperature by Peltier elements and
replenishing water replaces a corresponding fraction of the cooled
water. Since for storage of cold in this case only the specific
heat capacity of the water in the reservoir is available, large
volumes are required even for small capacities.
[0007] U.S. Pat. No. 5,544,489 discloses in this respect an
improvement in capacity by utilization of the melting enthalpy of
the water to be cooled. For this, on the cold side of the Peltier
element, ice is generated within a water reservoir, as a result of
which the energy density of the cold accumulator is markedly
increased.
[0008] However, both said apparatuses are opposed by the expected
high microbial loading due to stagnant water in a reservoir with
respect to approval under drinking water law.
[0009] EP 0 777 090 provides an aid in this respect with the
essential difference from U.S. Pat. No. 5,544,489 that the drinking
water to be cooled is passed through the ice-cooled reservoir in a
pipe coil and direct contact is therefore avoided. A problem in
this regard of the spatial dimensions of such an apparatus is that
the space filled by ice is no longer available for the drinking
water coil.
[0010] A fundamental problem of all known continuous-flow
Peltier-based chillers is the low efficiency of Peltier elements
which is predominantly determined by the temperature difference
between the cold and warm sides. Whereas the warm side, by use of
corresponding cooling bodies and aeration fans, is problem-free in
principle and technically solved, the cold side is a problem which
has not yet been solved to date. Owing to the low specific thermal
conductivity of the cold accumulator medium used [.lamda..sub.water
approximately 0.57 W/(mK), .lamda..sub.ice approximately 2.2
W/(mK)], there is an increase in the temperature difference and
thus an impairment of the efficiency.
[0011] The object of the present invention is to provide an
apparatus for cooling foods, in particular water-based drinks,
which is simple and inexpensive to produce and has a high cooling
capacity.
[0012] The object is achieved by the features specified in claim
1.
[0013] By means of the design according to the invention, for the
first time an apparatus for cooling foods, in particular
water-based drinks, is provided which represents a high-grade
solution for small equipment, in particular in the household or
restaurant. By means of the cold accumulator used according to the
invention and made of expanded graphite and a phase change material
which passes through its solid-liquid phase change at or above 273
K, that is the freezing temperature of water, preferably a few
.degree. C. (up to 10.degree. C.) above the freezing point of
water, a very effective cold accumulator is provided which firstly,
as a result of the graphite, has a high thermal conductivity, and
thereby ensures relatively rapid shock-like cooling, and which
secondly comprises a phase change material which, even without
complicated control technology, does not involve the risk that
water-based drinks freeze and form an ice block. In addition,
firstly the size of the cold accumulator required for good
performance is decreased, and secondly the space and costs of
comprehensive control are saved.
[0014] Both measures lead to optimum matching of the apparatus
according to the invention to the requirements in the chilling of
foods, in particular water-based drinks.
[0015] Advantageous developments may be found in the subclaims.
[0016] To remove the heat taken up by the cold accumulator,
preferably a Peltier element is provided which further has the
advantage that the liquid flowing through the line can be heated
for disinfection by reversing the polarity of the voltage supply of
the Peltier element. Peltier elements are very cheap. The
comparatively low thermal efficiencies of a Peltier element are of
less importance owing to the very effective storage material having
expanded graphite, in particular when there is the possibility of
being able to "charge" the cold accumulator in idle times of the
apparatus, for example during the night.
[0017] However, instead of a Peltier element, conventional
refrigerator technology can also be used, for example the absorber
or compressor technique for "charging" the cold accumulator. Thus
it is conceivable, for example, to integrate the cold accumulator
into a conventional refrigerator and there, either for equipping
the refrigerator for active and effective shock cooling, for
example to use it in the area of the freezer compartment, or to use
it for dispensing a drink, for example water, from a central water
supply, in or on the refrigerator, in the course of a shock-like
continuous-flow cooling.
[0018] In principle, however, the invention may also be used
advantageously wherever a high cooling capacity with periodic load
or fluctuating cooling power requirement must be provided
inexpensively with small spatial dimensions.
[0019] In order that the entire container is available for the
drinking water-bearing pipe geometry, in the invention use is made
of a material as cold accumulator medium which passes through a
phase change at, or a few .degree. C. above, the freezing point of
water, for which in principle salt hydrates, eutectic mixtures and
also paraffins are suitable.
[0020] To increase the efficiency of the Peltier element, the cold
accumulator medium is admixed with expanded graphite, as a result
of which the thermal conductivity can be increased by up to a
factor of 150.
[0021] The invention is in addition suitable for construction of a
cooling container, wherein the cold accumulator can be integrated
into an insulated wall of the cooling container, or into the
interior, wherein the interior can also be completely filled by the
cold accumulator. By means of the apparatus according to the
invention, for example inexpensively available commercially
conventional refrigerators can be refitted in this manner.
[0022] The invention can, for example, also be used as a
shock-cooling unit for dispensing drinking water into a cooling
container. The invention is also particularly suitable for
dispensing units, wherein, in the interior of a housing, a drink
source, for example a beer keg, can be received and the cold
accumulator is active both in the interior and in the dispense
line.
[0023] Examples of the invention will be described in more detail
hereinafter with reference to the drawings. In the drawings:
[0024] FIG. 1 shows a diagrammatic representation of a first
example of an apparatus according to the invention,
[0025] FIG. 2 shows the plan view onto FIG. 1,
[0026] FIG. 3 shows a diagrammatic representation of a further
example of an apparatus according to the invention,
[0027] FIG. 4 shows the depiction of the section A-A from FIG. 3
for a first arrangement of the line,
[0028] FIG. 5 shows the sectional view A-A from FIG. 3 for a second
arrangement of the line,
[0029] FIG. 6 shows a diagrammatic representation of an apparatus
according to the invention using refrigerator technology.
[0030] FIG. 1 shows a device according to the invention for
chilling foods having a cylindrical container 1 which has an
introduced line in the form of a pipe coil 8 through which passes a
water-based liquid to be cooled from an inlet 5 to an outlet 4. The
liquid to be cooled can be either the drink to be cooled,
preferably water with or without gas admixture (carbon dioxide
and/or oxygen) which originates from a water source, preferably the
central local water supply. Or, however, the liquid can be a
coolant, which is, however, preferably likewise water and
originates from the central water supply, but serves for cooling
foods or drinks at another point.
[0031] The container 1 is filled by a cold accumulator 6 which
comprises a composite material made of expanded graphite and also a
material which passes through a phase change at or above 273 K, the
phase change preferably being a few .degree. C. (up to 10.degree.
C., preferably 3.degree. to 5.degree. C.) above the freezing point
of water.
[0032] Suitable phase change materials are preferably salts and
also paraffins known for their phase change properties. In the
example shown, the graphite is present as free-flowing granules and
is impregnated with the phase change material. The heat taken up
from the liquid in the pipe coil 8 is taken off from the cold
accumulator 6 again by a suitable unit. The unit in the example
shown is a Peltier element 2 which is in intimate contact with the
cold accumulator 6 by its cold side. The hot side of the Peltier
element 2 is provided with an apparatus 3 for transporting away the
heat. The apparatus 3 can be any suitable apparatus and is in
particular a fan as is customarily used with Peltier elements. In
addition, measures can be taken to reverse the polarity of the
Peltier element 2 so that if appropriate the liquid flowing through
the line 8 can be heated for disinfection.
[0033] To improve the thermal conductivity, the point of the
container 1 at which the Peltier element 2 is mounted is made of a
readily-conducting material, in particular a metallic material.
[0034] Finally, a plurality of Peltier elements can be
provided.
[0035] In FIGS. 3 to 5, further examples of the apparatus according
to the invention for cooling foods are shown which differ from the
example according to FIGS. 1 and 2 only by the details described
hereinafter. The apparatus according to FIG. 3 also comprises a
container 1 which in this example, however, is rectangular, but can
equally be cylindrical, as in the first example. In the container
1, a cold accumulator 6 is accommodated which this time consists of
plate-type, expanded graphite which was impregnated with the same
phase change material which has already been described with
reference to FIG. 1. The cold accumulator has a layer structure,
with plates of the graphite material alternating with a layer-type
arrangement 7 of suitably shaped and laid lines which, however,
again extend from the container 1 by the water outlet 4 and the
water inlet 5. The layer-type arrangement 7 can contain, for
example, a meander-like line geometry 9 of FIG. 4 or a spiral-type
line geometry 10 of FIG. 5. Each line layer 7 is connected by inlet
and outlet in a manner which is not shown to the adjacent line
layers, with the first and last line layers being connected to the
water outlet 4 and the water inlet 5, respectively.
[0036] The line layers can either be laid as pipes, or in the shape
of profiled plates, wherein preferably two plates are provided in a
mirror image fashion with corresponding embossings of the size of
the half cross section of the line, and the plates are subsequently
laid one upon the other and are fastened to one another, so that
the embossings supplement each other to give continuous channels
which are closed on the periphery side. Not only the pipes but also
the profile plates consist of readily heat-conducting material, for
example metal. The lines 8, 9 or 10 preferably have a diameter
between 3 and 11 mm, in particular 4-10 mm, since, with this
diameter, in combination with a water pressure as is supplied on
average by a water pipe grid (1.5-4.5 bar) which, if appropriate,
can be set by a pump or a pressure-reducing valve to a constant
insignificantly varying pressure (.+-.0.5 bar), a strong flow
counteracting microbial infestation forms.
[0037] The layer-like arrangement according to FIGS. 3 to 5 is
preferably produced by compressing the line layers having the
graphite plates, which leads to a particularly intimate,
heat-transferring contact between the layers.
[0038] In this example also, the system for "charging" the cold
accumulator 6 preferably contains the Peltier element 2 already
described, wherein the Peltier element 2 is arranged in such a
manner that the surface normal to the graphite plates is oriented
in parallel to the surface of the Peltier element 2.
[0039] The examples corresponding to FIGS. 1 to 5 are preferably
constructed in the form of a cold battery, that is to say a
handleable unit. In this form, the apparatus according to the
invention can be installed anywhere where it is required, if
appropriate even retrospectively. It is only necessary that
measures are taken to connect the water inlet and outlet 4, 5 to a
water source, for example the local drinking water supply. However,
if appropriate, it is also possible to construct the apparatus
according to the invention as a cold battery without the Peltier
element and to use another technology for "charging" the cold
accumulator.
[0040] This can be, for example, the cooling unit of a conventional
refrigerator, for example an absorber or compressor refrigerator.
This case is illustrated in FIG. 6. FIG. 6 shows a conventional
refrigerator 11 which is provided with its own cooling unit 12. In
the refrigerator 11 a cold accumulator 6 of the invention is
installed which is constructed as a cold battery. The cold
accumulator 6 can, as shown in FIG. 6, be accommodated anywhere in
the interior 13 of the refrigerator 11, if appropriate also
retrospectively. In the example shown, it is accommodated in the
rear region opposite a door 14. The cold accumulator 6, however,
can also be accommodated anywhere in a wall 15 (including base and
upper cover or door 14) or in an intermediate base or the like.
[0041] The cold accumulator 6 is provided with the line 8 through
which a water-based liquid is passed. The water inlet 5 is
connected to a drinking water grid which is preferably detachable
via a valve 5a, for example a conventional water tap. The water
outlet 4 can be passed to a dispense point which is not shown.
[0042] The function of the Peltier element, here, however, is met
by the cooling unit 12 of the refrigerator 11. The cold accumulator
6 can, as shown, be provided only in one part of the interior 13,
but can also fill the entire interior 13.
[0043] The latter version leads to an apparatus for cooling drinks
which can be manufactured particularly inexpensively, the line
being passed through the entire interior filled with cold
accumulator 6.
* * * * *