U.S. patent application number 10/620177 was filed with the patent office on 2005-01-20 for absorption refrigerator with ice-maker.
This patent application is currently assigned to Dometic Appliances AB. Invention is credited to Hallin, Anders Bengt Ingemar.
Application Number | 20050011222 10/620177 |
Document ID | / |
Family ID | 34062725 |
Filed Date | 2005-01-20 |
United States Patent
Application |
20050011222 |
Kind Code |
A1 |
Hallin, Anders Bengt
Ingemar |
January 20, 2005 |
Absorption refrigerator with ice-maker
Abstract
Absorption refrigerator (1) including a cabinet having outer
walls (2, 3, 4, 5, 6) and at least one door (7, 8) encasing a low
temperature storage compartment (9) and a higher temperature
storage compartment (10), said compartments being separated by a
partition wall (11). An ice-maker is arranged in one of the
compartments. The refrigerator is cooled by an absorption
refrigerating system which includes an evaporator tube (20) in
which a refrigeration medium flows from an upstream end to a
downstream end of the evaporator tube, and which evaporator tube
comprises a first tube section (21) which is arranged to absorb
heat from the low temperature compartment, a second tube section
(22), which is arranged to cool the higher temperature compartment
and a third tube section (23) which is arranged to cool the
ice-maker. The first, second and third tube sections are connected
in series and the first tube section is arranged upstream of the
second tube section. In order to minimize the negative influence of
the operation of the ice-maker on the temperature in the freezer
compartment, the third tube section is arranged downstream of said
first tube section and upstream of said second tube section.
Inventors: |
Hallin, Anders Bengt Ingemar;
(Lidingo, SE) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET
SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
Dometic Appliances AB
|
Family ID: |
34062725 |
Appl. No.: |
10/620177 |
Filed: |
July 15, 2003 |
Current U.S.
Class: |
62/526 ; 62/340;
62/476; 62/524 |
Current CPC
Class: |
F25D 2400/30 20130101;
F25B 39/026 20130101; F25C 2400/10 20130101; F25D 11/027 20130101;
F25C 1/04 20130101; F25C 5/08 20130101 |
Class at
Publication: |
062/526 ;
062/524; 062/340; 062/476 |
International
Class: |
F25C 001/00; F25B
015/00; F25B 039/02 |
Claims
1. Absorption refrigerator (1) comprising: a cabinet having outer
walls (2,3,4,5,6) and at least one door (7,8), said cabinet
enclosing a low temperature storage compartment (9) and a higher
temperature storage compartment (10), said compartments being
separated by a partition wall (11), a device for ice fabrication,
and an absorption refrigerating system including an evaporator tube
(20) in which a refrigeration medium flows from an upstream end to
a downstream end of the evaporator tube, said evaporator tube
comprising a first tube section (21), arranged to absorb heat from
the low temperature compartment, a second tube section (22),
arranged to absorb heat from the higher temperature compartment,
and a third tube section (23) arranged to absorb heat from the ice
fabrication device, wherein the first, second and third tube
sections are connected in series and the first tube section is
arranged upstream of the second tube section, and wherein said
third tube section (23) is arranged to predominantly absorb heat
from the ice fabrication device by heat conduction and is arranged
downstream of said first tube section (21) and upstream of second
tube section (22).
2. Absorption refrigerator according to claim 1, wherein the first
(21) and third (23) tube sections are arranged in the low
temperature compartment (9) and the second tube section (22) is
arranged in the higher temperature compartment (10).
3. Absorption refrigerator according to claim 1, wherein the third
tube section is arranged in a separate ice fabrication
compartment.
4. Absorption refrigerator according to any of claims 1 to 3,
wherein the upstream end of the third tube section (23) is
connected directly to the downstream end of the first tube section
(21).
5. Absorption refrigerator according to any of claims 1 to 3,
wherein the upstream end of the second tube section (22) is
connected to the downstream end of the third tube section (23)
through a passive gas beat exchange tube section (28), arranged
inside one of the walls (2) of the cabinet.
6. Absorption refrigerator according to any of claims 1 to 3,
wherein the first tube section (21) comprises two non-coaxial tube
portions (21a), the axes of the non-coaxial tube portions of the
first tube section together defining a general extension plane of
the first tube section, and wherein the third tube section (23)
comprises two non-coaxial tube portions (23a), the axes of the
non-coaxial tube portion of the third tube section together
defining a general extension plane of the third tube section,
whereby said general extension plane of the first tube section is
essentially perpendicular to the general extension plane of the
third section.
7. Absorption refrigerator according to claim 6, wherein the
general extension plane of the first tube section (21) is
essentially vertical and generally parallel to the general
extension plane of the partition wall (11).
8. Absorption refrigerator according to any of claims 1 to 3,
wherein the ice fabrication device comprises heating means for
effecting partial melting of the ice for facilitating harvesting of
the ice.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an absorption refrigerator
including; a cabinet having outer walls and at least one door
encasing a low temperature storage compartment and a higher
temperature storage compartment, said compartments being separated
by a partition wall, a device for ice fabrication, and an
absorption refrigerating system including an evaporator tube in
which a refrigeration medium flows from an upstream end to a
downstream end of the evaporator tube, and which evaporator tube
comprises a first tube section which is arranged to absorb heat
from the low temperature compartment, a second tube section, which
is arranged to absorb heat from the higher temperature compartment
and a third tube section which is arranged to absorb heat from the
ice fabrication device, wherein the first, second and third tube
sections are connected in series and the first tube section is
arranged upstream of the second tube section.
BACKGROUND OF THE INVENTION
[0002] Such absorption refrigerators are commonly used e.g. in
recreation vehicles, mobile homes or at homes were AC power supply
is not available at all times.
[0003] Normally, at the prior art refrigerators of this type, the
lower temperature compartment is a freezer, which at modern
absorption refrigerators normally is maintained at -18.degree. C.
The freezer also accommodates the device for fabrication of ice,
often referred to as the ice-maker. The ice maker may in it's
simplest form be an ice-cube container but it may also comprise
more sophisticated devices with means for automatic water supply
and ice harvesting means including mechanical members and
electrical heating elements. The higher temperature compartment is
normally maintained at around +5.degree. C. and could be referred
to as a refrigerator compartment.
[0004] The evaporator tube includes an upstream tube section, which
is dedicated for cooling the ice-maker. Downstream of this
ice-maker tube section and in direct connection to its downstream
end, an intermediate tube section is arranged for cooling the
freezer. Downstream of the freezer section, a downstream
refrigerator section of the evaporator tube is arranged for cooling
the higher temperature refrigerator compartment. At some
applications both the freezer and the ice-maker are cooled together
by one single evaporator tube section which is arranged upstream of
the refrigerator tube section.
[0005] The evaporator may be provided with various types of heat
conducting members for conducting heat from the items to be cooled,
i.e. the freezer and refrigerator compartments and the ice maker,
to the respective evaporator tube sections. As an example, the
ice-maker section of the evaporator may be provided with a heat
conducting plate, which is arranged to support the ice-cube
container and which conducts heat from the container to the
ice-maker section of the evaporator. The freezer and refrigerator
sections may be provided with flanges or baffles, which conduct
heat from the air in the freezer and refrigerator compartments to
the evaporator freezer and refrigerator section respectively.
[0006] The evaporator reaches its lowest evaporation temperature at
the upstream end. Downstream of the upstream end, the evaporation
temperature rises gradually when the cooling medium in the
evaporator tub absorbs heat from the ice-maker, freezer compartment
and refrigerator compartment.
[0007] A problem at this known type of absorption refrigerator is
that it is difficult to achieve a high enough cooling power of the
refrigeration system to maintain the freezer compartment at the low
temperature which is desired. As mentioned above, it is often
desired to keep the temperature in the freezer compartment as low
as approximately -18.degree. C. The total cooling power of the
absorption refrigerating apparatus is, among other factors, limited
by the heat transfer capacity of the evaporator, which in turn
depends on the total length of the evaporator tube. This length in
turn, is limited by the dimensions of the refrigerator cabinet and
by the fact that the evaporator tube needs to be designed with a
downward inclination over its entire length, from the upstream to
the downstream end.
[0008] At the upstream end of the evaporator tube, the evaporation
temperature of the refrigeration medium is normally approximately
-30.degree. C. During manufacturing of ice, i.e. during freezing of
water in the ice-maker, the ice-maker section of the evaporator
absorbs heat from the ice-maker. This heat absorption rises the
evaporation temperature of the refrigeration medium so that it, at
the entrance of the freezer section of the evaporator tube, is
approximately -24.degree. C. and at the exit approximately
-20.degree. C. Thus, during manufacturing of ice, the average
driving temperature difference between the desired freezer
temperature and the evaporation temperature of the refrigeration
medium would then be only about 2.degree. C. Such a small driving
temperature difference makes it impossible to bring down the
freezer to the desired temperature, especially when additional heat
enters into the freezer, e.g. due to opening of the freezer door,
placement of non-frozen items in the freezer or due to inward heat
transfer through the cabinet walls. Especially when utilizing some
kinds of automatic ice-makers, this problem is further increased.
During harvesting of the ice in such automatic ice-makers, the
ice-container is heated by an electrical heating element. Hereby,
the heat supplied to, and absorbed by the refrigeration medium in
the ice-maker section of the evaporator tube is further increased.
The cooling capacity available at the freezer evaporator section,
downstream of the ice-maker evaporator section is thus further
reduced during automatic harvesting of ice. In practice, it has
shown that the temperature in the freezer compartment rises between
6-9.degree. C. during operation of such automatic ice-makers. Also
at the type of absorption refrigerators, where the ice
manufacturing device and the freezer compartment are cooled by one
and the same evaporator tube section, the same negative influence
of the ice-maker on the cooling capacity in the freezer compartment
applies.
BRIEF SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
provide an absorption refrigerator having a low temperature
compartment, a higher temperature compartment and an ice
manufacturing device, at which absorption refrigerator the total
cooling power of the refrigeration apparatus is more favorably
distributed between the two compartments and the ice-maker.
[0010] It is a further object to provide such an absorption
refrigerator, which facilitates to maintain the temperature in the
freezer compartment as low as desired, also when additional heat is
entered into the freezer compartment.
[0011] Another object is to provide such an absorption refrigerator
at which it is possible to use sophisticated ice-making devices
including heating elements without adversely affecting the cooling
capacity of the freezer compartment.
[0012] These and other objects are achieved with an absorption
refrigerator according to the first paragraph of this description
in which refrigerator the third tube section is arranged to
predominantly absorb heat from the ice fabrication device by heat
conduction and is arranged downstream of said first tube section
and upstream of said second tube section.
[0013] Through this arrangement of the different sections of the
evaporator tube, the first evaporator tube section, which absorbs
heat from the freezer compartment is arranged the most upstream of
the three sections. Hereby it is assured that that section of the
evaporator tube which exhibits the lowest evaporation temperature
cools the item, which needs to be maintained at the lowest
temperature, i.e. the freezer compartment. Thereby, it is also
assured that the greatest possible driving temperature-difference
is used for maintaining the freezer compartment at the desired
temperature.
[0014] Since the ice-manufacturing device needs to be kept only at
about -10.degree. C. for sufficiently quick freezing of water to
ice, the increase of the evaporation temperature, which the
refrigeration medium undergoes during its absorption of heat in the
freezer tube section of the evaporator does not adversely affect
the capability of the ice-maker section to maintain the ice-maker
at a sufficiently low temperature.
[0015] The refrigerator compartment in turn, needs only to be kept
at about +5.degree. C. Therefore, the increase of the evaporation
temperature, which the refrigeration medium undergoes during its
passage through the ice-maker section of the evaporator does not
adversely affect the ability of the refrigeration section to
maintain the refrigeration compartment at the desired
temperature.
[0016] Thus, by the arrangement of the different evaporator
sections according to the invention, it is assured that the total
cooling capacity generated by the refrigeration apparatus is
distributed by the evaporator to the items to be cooled in the most
effective manner.
[0017] Further objects and advantages of the invention are set out
in the depending claims.
DETAILED DESCRIPTION OF THE INVENTION
[0018] An exemplifying embodiment of the invention will now be
described with reference to the accompanying drawings in which:
[0019] FIG. 1 is a top elevation view, with parts of the walls
broken away, of a refrigerator cabinet according to the present
invention.
[0020] FIG. 2 is a perspective view from behind, with parts broken
away, of the refrigerator in FIG. 1.
[0021] In the figures a side-by-side absorption refrigerator 1 is
shown. The cabinet includes a rear wall 2, two side walls 3, 4, a
top-wall 5 and a bottom-wall 6. These outer walls 2-6, together
with two front doors 7, 8 enclose a low temperature storage
compartment 9 and a higher temperature storage compartment 10. The
outer walls 2-6 and the front doors 7, 8 all include an outer and
an inner shell between which heat insulating material, such as
polyurethane foam, is arranged. The two compartments 9, 10 are
hermetically sealed from each other by a vertical partition wall
11, which extends perpendicular to and from the rear wall 2,
between the rear wall 2 and the front of the cabinet 1, in such
away that the doors 7 and 8, when closed, sealingly rest against
the front of the partition wall 11. The freezer compartment 9 is
thus defined by the (in FIG. 1) left front door 7, the partition
wall 11, the side wall 3, and respective portions 2a, 5a, and 6a of
the rear wall, top wall and bottom wall. The higher temperature
compartment 10 is analogously defined by the (in FIG. 1) right
front door 8, the partition wall 11, the side wall 4, and
respective portions 2b, 5b, 6b of the rear wall, top wall and
bottom wall. The partition wall is placed approximately 1/3 of the
total width of the cabinet from one side-wall 3, so that the
width-relationship between the freezer compartment 9 and the
refrigerator compartment is approximately 1:2.
[0022] During operation, the temperature in the freezer compartment
is normally kept at about -18.degree. C., whereas the higher
temperature compartment normally is kept at about +5.degree. C. The
higher temperature compartment 10 could also be referred to as a
refrigerator compartment.
[0023] An absorption refrigerator system including a conventional
boiler, condenser, and absorber (neither of which is shown) is
arranged at the back of the cabinet, outside the rear wall 2. The
refrigerator system also includes an evaporator, generally
indicated by reference number 20. The evaporator 20 is formed of an
evaporator tube, which includes a first evaporator tube section 21
for cooling the freezer compartment and a second evaporator tube
section 22 for cooling the higher temperature compartment 10. The
first section 21 is arranged inside the freezer compartment 9 and
the second section 22, inside the higher temperature compartment
10.
[0024] The evaporator tube 20 also includes a third tube section 23
for cooling a device (not shown) for fabrication of ice,
hereinafter referred to as an ice-maker. The ice-maker may in its
simplest form be an ice-cube container, which is placed onto the
third evaporator section. It may however also be a more
sophisticated automatic device, including means for automatic water
supply, mechanical means for harvesting and crushing the ice as
well as electrical heating elements for partially melting the ice
prior to harvesting. Regardless of which type of ice maker is used,
it is arranged such that the predominant amount of heat, which is
removed from the water during the fabrication of ice, is conducted
to the third section of the evaporator.
[0025] The three evaporator sections 21, 22 and 23 are arranged in
series such that the evaporator tube is formed by one single
continuous tube, which includes the three sections, one after the
other. The first section 21 for cooling the freezer is arranged the
most upstream. The third section 23 for cooling the ice-maker is
arranged directly downstream of the first section. The second
section 22 for cooling the refrigerator is arranged downstream of
the third section 23.
[0026] At the upper, upstream end 24 of the evaporator 20, a first
conduit 25 supplies the coolant, such as liquid ammonium, from the
condenser to the evaporator 20. At the same upstream end 24, a
second conduit 26 supplies poor gas from the absorber.
[0027] The first evaporator tube section 21 is arranged immediately
downstream of the upstream end 24 of the evaporator. The first
evaporator section 21 comprises four generally straight tube
portions 21a, which are connected, one after the other through
three tube bends 21b. The straight tube portions 21a and the tube
bends 21b are arranged vertically, one over the other, generally in
the same vertical plane. At the downstream end of the lowest
straight tube portion 21a, a further tube bend 21c connects the
lowest straight tube portion with a further straight tube portion
21d, which extends generally perpendicular to the vertical plane
defined by the four straight tube portions 21a, in proximity to the
rear wall 2 of the cabinet. At the downstream end of this straight
tube portion 21d, the third section 23 of the evaporator is
connected to the first section through a tube bend 27. The third
section 23 is generally U-shaped and includes two generally
straight tube portions 23a connected with each other by a tube bend
23b. The U-shaped third section 23 is arranged generally
horizontal, whereby the two straight tube portions 23a and the tube
bend 23b are arranged in the same general horizontal plane.
[0028] At a lead-through 29, which is arranged through the inner
shell of the freezer rear wall portion 2a, at the downstream end of
the third evaporator section 23, the third evaporator section 23 is
connected to a passive evaporator section 28. The passive section
28 extends inside the rear wall 2 at a slight downward slope, past
the partition wall 11 This passive section 28 does not absorb heat
from any of the two compartments. However, it functions as a heat
exchanger absorbing heat from the mediums in the conduits 25 and
26. The passive tube section 28 is connected to the upstream end of
the second evaporator section 22 at a lead-through 30 in the
refrigerator portion 2b of the rear wall 2. The second evaporator
section 22 includes two generally straight tube portions 22a, which
are arranged, one over the other, generally in the same vertical
plane and connected by a tube bend 22b. At the down-stream end of
the second evaporator section. 22, a lead-through 31 leads the
evaporator tube into the rear wall 2, where the evaporator tube,
together with the coolant supply conduit 25 is connected to a
co-axial gas heat exchanger tube 32. The co-axial tube 32 extends
in the rear wall 2, in a generally U-shaped manner and exits
through the outer shell of the rear wall. At the back of the
refrigerator cabinet, the co-axial tube is connected to the
absorber of the refrigerating apparatus (not shown).
[0029] During operation, when water is frozen to ice in the
ice-maker, the temperature of the refrigeration medium at the
upstream end 24 of the first evaporator section 21 is typically
maintained at approx. -30.degree. C. At the downstream end 27 of
the first evaporator section 21, the coolant temperature has
typically risen to approx. -24.degree. C. During the passage of the
coolant through the third evaporator section 23, the refrigeration
medium temperature is raised to approximately -20.degree. C. During
the passage of the coolant through the passive evaporator section
23, the temperature of the refrigeration medium increases due to
absorption of heat from the adjacent conduits 25, 26, whereby the
temperature at the upstream end of the second evaporator section 22
is about -16.degree. C. During passage through the second
evaporator section 22 the coolant temperature is typically raised
to approx. -12.degree. C. The different temperatures described
above vary over the working cycle of the ice-maker and depending on
external conditions as well as customer use. The exemplifying
values are given for illustrating a typical operation
situation.
[0030] For enhancing the heat transfer from the air in the freezer
compartment 9 and the refrigerator compartment 10 to the respective
evaporator sections 21 and 22, flanged baffle elements 34, 35 of a
heat conducting material are attached to the respective evaporator
section. The baffle elements 34, 35 exhibit a generally comb-shaped
transverse section and include a base and a plurality of flanges
having a vertical longitudinal direction.
[0031] By the arrangement of the first, second and third evaporator
section 21, 22 and 23 described above, it is accomplished that,
during operation of the refrigerating system, the freezer
compartment is always cooled by the coolest part of the evaporator,
which part also has the lowest evaporation temperature of the
refrigerant medium. Hereby, it is assured that the driving
temperature difference, between the air in the freezer and the
freezer section of the evaporator, for cooling the freezer
compartment always is the greatest possible. This in turn
contributes to making it possible to, at all times, maintain the
air in the freezer compartment at temperatures as low as
-18.degree. C., which is often desired at modern absorption
refrigerators.
[0032] The invention further accomplishes that heat added from the
ice-maker, during cooling of the water and during heating of the
ice for facilitating harvesting, does not significantly affect the
evaporation temperature of the refrigeration medium in the freezer
section of the evaporator. Studies have shown that the evaporation
temperature of the freezer section of the evaporator rises only
about 2.degree. C. during operation of the ice-maker at a
refrigerator according to the invention. The operation of the
ice-maker thereby, does not force the refrigeration apparatus to
compensate for heat added from the manufacturing or harvesting of
ice. The invention thus provides an absorption refrigerator, at
which the temperature of the freezer compartment may be maintained
at the desired level regardless of the operation of the
ice-maker.
[0033] Above, an exemplifying embodiment of the invention has been
described. The invention may however be modified within the scope
of the appending claims. Instead of being arranged in the lower
temperature freezer compartment, the third section of the
evaporator may be arranged in the higher temperature refrigerator
compartment. In such case the third section is arranged downstream
of the passive evaporator section and upstream of the second
evaporator section. The third section of the evaporator may also be
arranged in a separate ice-maker compartment.
[0034] The first, second and third evaporator sections may have
other tube configurations than the ones described above. The may
for instance be formed by fewer or more interconnected straight
tube portions or they may be formed by tube sections which are
curved along their whole lengths.
[0035] In the above-illustrated embodiment, the partition wall
hermetically seals the freezer and the higher temperature
compartments from each other. Small deviations from this principle
may be allowed, as long as no significant heat transfer is effected
between the two compartments
* * * * *