U.S. patent application number 12/884239 was filed with the patent office on 2011-01-06 for refrigerator with moisture adsorbing device.
This patent application is currently assigned to WHIRLPOOL CORPORATION. Invention is credited to DIEGO BARONE, LORENZO BIANCHI, ENRICA MONTICELLI, LUCA NARDI, GIULIANO ROSI.
Application Number | 20110000235 12/884239 |
Document ID | / |
Family ID | 36617010 |
Filed Date | 2011-01-06 |
United States Patent
Application |
20110000235 |
Kind Code |
A1 |
BARONE; DIEGO ; et
al. |
January 6, 2011 |
REFRIGERATOR WITH MOISTURE ADSORBING DEVICE
Abstract
The present invention relates to a refrigerator or freezer
having a cabinet forming at least a freezer compartment, at least
one door for opening and closing the cabinet, and an adsorbing
device containing a desiccant material for collecting moisture from
air inside the cabinet, wherein the adsorbing device is mounted
inside the cabinet.
Inventors: |
BARONE; DIEGO; (Bergamo,
IT) ; MONTICELLI; ENRICA; (Varese, IT) ;
BIANCHI; LORENZO; (Varese, IT) ; ROSI; GIULIANO;
(Siena, IT) ; NARDI; LUCA; (Siena, IT) |
Correspondence
Address: |
WHIRLPOOL PATENTS COMPANY - MD 0750
500 RENAISSANCE DRIVE - SUITE 102
ST. JOSEPH
MI
49085
US
|
Assignee: |
WHIRLPOOL CORPORATION
BENTON HARBOR
MI
|
Family ID: |
36617010 |
Appl. No.: |
12/884239 |
Filed: |
September 17, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11668506 |
Jan 30, 2007 |
7797963 |
|
|
12884239 |
|
|
|
|
Current U.S.
Class: |
62/94 ;
62/271 |
Current CPC
Class: |
F25D 17/047 20130101;
F25D 2317/0411 20130101; F25D 17/042 20130101; F25D 2400/10
20130101; F25D 23/026 20130101; F25D 21/04 20130101; F25B 39/02
20130101 |
Class at
Publication: |
62/94 ;
62/271 |
International
Class: |
F25D 17/06 20060101
F25D017/06; F25B 15/00 20060101 F25B015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2006 |
EP |
06101048.4 |
Claims
1. A refrigeration apparatus comprising: a cabinet forming at least
a freezer compartment; at least one door for opening and closing
the cabinet; an evaporator; and an adsorbing device containing a
desiccant material for collecting moisture from air inside the
cabinet, wherein the adsorbing device is mounted inside the
cabinet.
2. The refrigeration apparatus of claim 1, further including a
fresh food storage compartment and a mullion separating the fresh
food storage compartment and freezer compartment and the adsorbing
device is provided in the mullion.
3. The refrigeration apparatus of claim 1, wherein the adsorbing
device is placed in contact with the evaporator.
4. The refrigeration apparatus of claim 1, wherein the adsorbing
device is mounted at the bottom of the freezer compartment.
5. The refrigeration apparatus of claim 3, wherein the adsorbing
device is mounted to the evaporator using a removable support
system.
6. The refrigeration apparatus of claim 1, wherein the adsorbing
device is removably mounted to the refrigeration apparatus.
7. An adsorbing device comprising: an enclosure; and a desiccant
material, wherein the adsorbing device is mounted inside a
refrigeration apparatus, and the desiccant material adsorbs
moisture from air inside the refrigeration apparatus.
8. The adsorbing device of claim 7, wherein the enclosure is
box-shaped and has openings to allow passage of air through the
desiccant material.
9. A method of defrosting an evaporator in a refrigeration
apparatus having a cabinet including a food storage compartment and
an adsorbing device inside the cabinet by adsorbing moisture from
air inside the food storage compartment.
10. The method of claim 9, wherein the adsorbing device further
adsorbs frost present on the evaporator.
11. The method of claim 9, further comprising the steps of:
removing the adsorbing device; regenerating the device; and
returning the device to the refrigeration apparatus.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of prior application Ser.
No. 11/668,506, filed Jan. 30, 2007.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a refrigerator comprising a
cabinet forming a food storage space and a door for opening and
closing the space.
[0004] 2. Description of the Related Art
[0005] It is well known that direct cooled freezers present the
problem of manual defrosting of evaporators, due to the frost
build-up during normal operation of the direct cooled freezer.
[0006] Manual defrosting of direct cooled freezers can be very time
consuming for users. A user must remove all of the frozen goods
from the freezer and manually initiate the defrosting routines.
This causes the user to schedule this activity carefully in
advance, to avoid spoiling the frozen goods during the defrost
operation.
[0007] The most prevalent alternative technique to manually defrost
is related to hot gas defrosting of a freezer evaporator, which
allows quick defrosting by hot gas circulation which melts the
frost layer. However, this is not an easy operation since the user
still must remove all of the frozen goods from the freezer, then
make the frost layer melt by the hot gas defrosting, and finally
put the goods back in the freezer before they thaw. Another
technology is the no-frost refrigerator/freezer where the cold
surfaces of the evaporator are located outside of the freezer
cavity in a separate space, and cold air is forced by a fan to flow
over the evaporator. In this way, the frost layer can be melted
using an electric heater and defrost water is discharged out of the
compartment by a drain pipe. This technology provides automatic
defrosting but consumes more energy.
[0008] The automatic defrosting offered by the no-frost freezers
has additional disadvantages, such as reduced volume available for
the frozen goods. Also, the no-frost freezers draw moisture from
the frozen goods, so the user must wrap the goods in plastic or
store the goods in boxes to prevent dehydration. Moreover, no-frost
freezers are costly and less energy efficient.
[0009] Thus, an improvement over the prior art would be to improve
defrosting of direct cooled freezers without the disadvantages of
present manual defrosting or the disadvantages of automatic
defrosting of no-frost freezers.
SUMMARY OF THE INVENTION
[0010] Accordingly, the present invention is directed to a
refrigerator having an adsorbing device to improve the defrosting
process.
[0011] One embodiment of the invention is a refrigerator having a
cabinet forming a fresh food storage compartment and a freezer
compartment, at least one door for opening and closing the cabinet,
and an adsorbing device containing a desiccant material for
collecting moisture from air inside the cabinet, wherein the
adsorbing device is mounted inside the cabinet.
[0012] The adsorbing device may be mounted inside the food storage
compartment. Additionally, it may be box-shaped and have inlet and
outlet apertures to allow passage of air. The adsorbing device may
comprise an enclosure having a plurality of openings. The desiccant
material may include at least one of the following: silica gel,
clay, zeolites, or mixtures thereof.
[0013] The adsorbing device may be mounted on the door and
connected to external ambient air through an opening in the door.
Additionally, the refrigerator may further comprise a valve at the
opening of the door to control flow of air through the adsorbing
device.
[0014] The refrigerator may further comprise a freezer compartment
and evaporator. In this embodiment, the adsorbing device may be
mounted on the door and connected to external ambient air through a
first opening and to the freezer compartment through a second
opening. Alternatively, the adsorbing device may be placed in
contact with the evaporator using a removable support system.
Alternatively, the adsorbing device may be placed at the bottom of
the freezer compartment.
[0015] The refrigerator may further include a mullion separating
the food storage space into two cavities, wherein the adsorbing
device is placed in the mullion.
[0016] The adsorbing device may be removably mounted to the
refrigerator.
[0017] Another embodiment of the invention is an adsorbing device
including an enclosure and a desiccant material, wherein the
adsorbing device is mounted within a refrigerator and the desiccant
material adsorbs moisture from air inside the refrigerator.
[0018] The enclosure may be box-shaped and may have openings to
allow passage of air through the desiccant material.
[0019] The invention further includes a method of defrosting an
evaporator in a refrigerator having a food storage compartment and
an adsorbing device by adsorbing moisture from air inside the food
storage compartment.
[0020] The adsorbing device may further adsorb frost present on the
evaporator.
[0021] The method may further comprise the steps of removing the
adsorbing device, regenerating the device, and returning the device
to the refrigerator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will now be described in more detail,
by referring to the attached drawings in which:
[0023] FIG. 1 is a cross sectional view of a freezer according to a
first embodiment of the invention;
[0024] FIG. 2 is an enlarged detail of FIG. 1;
[0025] FIG. 3 is a cross sectional view of a freezer according to a
second embodiment of the invention;
[0026] FIG. 4 is an enlarged detail of FIG. 3;
[0027] FIG. 5 is a cross sectional view of a refrigerator having a
freezer compartment in the lower portion of the cabinet, according
to a further embodiment of the present invention;
[0028] FIG. 6 is an enlarged view of a detail of FIG. 5;
[0029] FIG. 7 is a cross sectional view of a refrigerator having a
freezer compartment in the upper portion of the cabinet, according
to a further embodiment of the present invention;
[0030] FIG. 8 is an enlarged view of a detail of FIG. 7;
[0031] FIG. 9 is a table showing the results of the two embodiments
of FIGS. 1 and 3; and
[0032] FIG. 10 is a plot showing results from a freezer according
to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] With reference to FIGS. 1 and 2, a first embodiment of a
freezer 10 is shown. The freezer 10 includes a desiccant device 12
to replace the usual separator (mullion) which divides the cavity
in two zones, one of which may be above the compressor compartment.
As shown in FIGS. 1 and 2, the desiccant device 12 may be located
within the freezer compartment, may be box-shaped, and may hold at
least 1.5 kg of silica gel or other desiccant materials. The
position of the device inside the enclosure, the amount of
desiccant and the presence of a forced air circulation are several
of the key performance drivers of the device.
[0034] The desiccant device 12 generally includes an enclosure
which holds a sufficient amount of desiccant or moisture adsorbing
material according to the internal volume of the enclosure of the
freezer itself. The enclosure may comprise a box, disc, or various
other shapes and may be constructed of various materials, such as
plastic or metal. The enclosure may have solid walls, mesh walls,
or walls having a plurality of openings to allow air to flow
through the moisture adsorbing material. It may have one or more
inlet and outlet apertures for allowing passage of air. It can be
readily understood that the size, geometry and material of the
enclosure could be changed without altering the function of the
invention.
[0035] Moisture adsorption materials collect moisture from the air
by physically trapping water vapor molecules inside molecular
sieves located inside the material itself. An ideal moisture
adsorbing material collects moisture from the air inside the
freezer by adsorption, lowering the partial pressure of water vapor
and physically neglecting sublimation of water vapor to frost. Due
to this moisture adsorption, there is less free water vapor in the
air inside the enclosure to sublimate and form a frost layer on the
evaporator.
[0036] When frost is already present on the evaporator, lowering
the partial pressure of water vapor in the air makes the frost
physically de-sublimate and then it migrates into the desiccant
device by means of permeation and diffusion. This ensures that
until the desiccant capacity is depleted, all the water vapor
entering the freezer enclosure will be trapped in the desiccant
device instead of sublimating into frost.
[0037] Desiccant materials can be used at temperatures of the order
of -18.degree. C., and at such low temperature the water adsorption
behaviour of these materials is still satisfactory.
[0038] Many desiccant materials already known in the art can be
used, including silica gel, clay, and zeolites, among many others.
Additionally, specially engineered materials designed to improve
their moisture adsorbing capabilities at low temperatures may be
used. Zeolites have shown to be particularly suitable for use at
low temperatures. In particular, type A zeolites, which are
supported by clays which do not alter the adsorptive properties of
the molecular sieve, are especially suitable. These zeolites
include attapulgite, kaolin, sepiolite, palygorskite, kaolinite,
bentonite, montmorillonite, illite, chlorite, and bentonite-type
clay. Other types of zeolites may also be used, including chabazite
(zeolite D), clinoptiloite, erionite, faujasite (also referred to
as zeolite X and zeolite Y), ferrierite, mordenite, and zeolite
P.
[0039] In the embodiment shown in FIGS. 1 and 2, an axial fan 14
may be used to force air circulation through the desiccant device
12. However, the axial fan 14 is not necessary for the invention to
operate sufficiently. Furthermore, the axial fan may be used in
other embodiments of the invention.
[0040] The desiccant device 12 may be provided in several locations
in order to adsorb moisture from the air inside the freezer. For
example, it may be provided within the freezer compartment,
positioned to utilize a small portion of the available volume.
Alternatively, the desiccant device 12 may be provided within the
door to the freezer compartment or within the insulation of the
freezer. The desiccant device 12 may also be mounted to the
evaporator. In order to overcome the limitations in the performance
of the desiccant materials available on the market, the applicant
has optimized how the desiccant device is placed inside the
freezer, developing specific configurations that bring significant
advantages to the final user.
[0041] FIGS. 3 and 4 illustrate an alternative embodiment of the
invention. In this embodiment, the desiccant device 16 may be
placed on the inner door 15 of the freezer. The desiccant device 16
may be connected to the external ambient air by a pipe 18 equipped
with a one-way valve 20. The desiccant device 16 is able to hold at
least 1.5 kg of silica gel or other desiccant materials. When the
freezer 10 is operating, its pressure fluctuations draw moist air
inside through the door gasket. Using the present invention,
pressure equilibrium is achieved but the air drawn in passes
through the desiccant device 16 where its moisture content is
adsorbed.
[0042] An alternative embodiment of the invention includes placing
the desiccant device on the outer door of the freezer. The device
may be connected to the external ambient air by a pipe, and may be
connected to the internal ambient by a pipe equipped with a one-way
valve passing through the door. Locating the desiccant device
outside of the freezer has several advantages. For example, the
performance of the desiccant is higher at room temperature.
Additionally, placing the desiccant device outside of the enclosure
avoids loss of storage space in the freezer. However, this location
has the disadvantage of becoming saturated faster than in other
embodiments, resulting in higher maintenance costs and more
frequent replacements for the user.
[0043] Another embodiment of the present invention is shown in
FIGS. 5 and 6 which relates to a refrigerator 11 having a
bottom-mount freezer 22. In this embodiment a desiccant device 24
is preferably located on the upper evaporator grid 22a. The
desiccant device may alternatively be located within the freezer
compartment or mounted to the door of the freezer compartment. The
device 24 may hold at least 4.6 kg of silica gel or other desiccant
materials and may include at least one fan 24a to push air into the
desiccant. The device may also operate successfully using natural
air circulation without fans.
[0044] Another embodiment of the invention is shown in FIGS. 7 and
8, which relates to a refrigerator 26 having a "top mount" freezer
28. For this embodiment, the evaporator may be foamed into the
cabinet. The desiccant device 30 may be located on the bottom of
the freezer 28 and preferably in a rear portion thereof. The device
may alternatively be located elsewhere in the freezer, or mounted
to the door of the freezer compartment. The desiccant device 30 may
hold at least 2.5 kg of silica gel or other desiccant materials.
The device may include at least one fan 32 to push air into the
desiccant.
[0045] The present invention may also be used with other
refrigerator configurations, such as a side-by-side refrigerator.
The location, size and geometry of the desiccant device may change
and be optimized based on the refrigerator configuration without
altering the function of the invention.
[0046] The table shown in FIG. 9 includes experimental data from a
group of freezers according to the first two embodiments of the
invention, as shown in FIGS. 1 and 3. The table shows the moisture
adsorption process over 56 days, as measured by the weight of the
desiccant device. In this experiment, three freezers were equipped
with the desiccant device positioned in three different
configurations. For instance, in one configuration, the desiccant
device was placed in the separator without a fan (tests 3 and 4).
In a second configuration, the desiccant device was placed in the
separator with a fan (tests 5 and 6). Finally, in a third
configuration, the desiccant device was placed on the internal
surface of the door (tests 7 and 8). The weight in grams of these
devices was measured weekly. The results are evidence of the
adsorption process and were used to determine the quantity of
desiccant needed for each type of configuration and to determine
its capacity at saturation.
[0047] The plot of FIG. 10 shows the output of a mathematical model
developed to extrapolate the behavior of the desiccant device over
a long period of time. It shows that it is possible to delay the
manual defrosting of a freezer according to the embodiment shown in
FIGS. 5 and 6, from a 1-year frequency to a 2-year frequency. This
tool allows us to study the behavior of the device in any
embodiment and under a variable set of assumptions. The basic
assumptions have been confirmed by experimental activity, in
particular by measuring the maximum quantity of frost allowed in
the enclosure, the maximum quantity of adsorbed moisture in the
desiccant at saturation, and the speed of the adsorption inside the
desiccant. In the plot, the line "A" shows the amount of moisture
entering the enclosure, thus creating a frost layer in a
non-protected freezer. Line "B" shows the amount of moisture
available for frost formation when a desiccant device is included,
according to an embodiment of the present invention. Line "B"
relates to a desiccant device containing approximately 2.3 kg of
desiccant material. Line "D" is the weight of the desiccant device,
which increases over time due to adsorption of moisture. Therefore,
line "B" is the result of the difference between lines "A" and "D".
Line "C" is the equivalent of line "B" when approximately 4.5 kg of
desiccant material is used. The plot shows is that in a 1-year time
frame, only a fraction of the total amount of moisture remains
available for frost formation, thus postponing the required date
for manual defrosting.
[0048] The solution according to an embodiment of the invention
provides users with an improved method to perform manual defrosting
of a direct cooled freezer. Since moisture is collected inside the
desiccant device, it is easy to remove the device from the freezer
without turning it off. Thus, the device may be easily replaced or
regenerated in a microwave oven or cooking oven and then returned
to the freezer.
[0049] Additionally, according to the performance of the desiccant
material and to its adsorption capacity, the manual defrost can be
delayed in time, thus reducing the frequency of manual defrosting
for the user, or it can be completely avoided by regeneration of
the device.
[0050] The defrosting operation by using a desiccant device is an
improvement over the prior art because there is no need to remove
the frozen goods and turn the freezer off or do any operation to
initiate the defrosting process. Thus, the freezer operation is not
interrupted and the inconvenience of removing the frozen goods is
avoided.
[0051] While the present invention has been described with
reference to the above described embodiments; those of skill in the
art will recognize that changes may be made thereto without
departing from the scope of the invention as set forth in the
appended claims.
* * * * *