U.S. patent application number 10/619675 was filed with the patent office on 2005-01-20 for absorption refrigerator.
This patent application is currently assigned to Dometic Appliances AB. Invention is credited to Hallin, Anders Bengt Ingemar, Kornelind, Johnny.
Application Number | 20050011220 10/619675 |
Document ID | / |
Family ID | 34062615 |
Filed Date | 2005-01-20 |
United States Patent
Application |
20050011220 |
Kind Code |
A1 |
Hallin, Anders Bengt Ingemar ;
et al. |
January 20, 2005 |
ABSORPTION REFRIGERATOR
Abstract
An 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 essentially
sealed from each other and separated by a partition wall (11),
which partition wall is arranged inside the cabinet and generally
perpendicular to a first wall (2) of said outer walls. The
refrigerator further comprises an absorption refrigerating system
including an evaporator tube (20), having a first section (21) for
absorbing heat from the low temperature compartment and a second
section (22) for absorbing heat from the higher temperature
compartment, said second section being arranged downstream said
first section. In order to reduce heat transfer into the cabinet
through the outer walls, a major part of the first section is
arranged generally in parallel with said partition wall.
Inventors: |
Hallin, Anders Bengt Ingemar;
(Lidingo, SE) ; Kornelind, Johnny; (Tyreso,
SE) |
Correspondence
Address: |
PEARNE & GORDON LLP
1801 EAST 9TH STREET
SUITE 1200
CLEVELAND
OH
44114-3108
US
|
Assignee: |
Dometic Appliances AB
|
Family ID: |
34062615 |
Appl. No.: |
10/619675 |
Filed: |
July 15, 2003 |
Current U.S.
Class: |
62/476 ; 62/443;
62/486; 62/526 |
Current CPC
Class: |
F25B 39/026 20130101;
F25D 11/027 20130101 |
Class at
Publication: |
062/476 ;
062/486; 062/443; 062/526 |
International
Class: |
F25D 011/02; 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
essentially sealed from each other and separated by a partition
wall (11), said partition wall being arranged inside the cabinet
and generally perpendicular to a first wall (2) of said outer
walls, and an absorption refrigerating system including an
evaporator tube (20) comprising a first evaporator tube section
(21) for cooling the low temperature compartment and a second
evaporator tube section (22) for cooling the higher temperature
compartment, said second evaporator tube section being arranged
downstream of said first evaporator tube section with respect to a
direction of flow of a coolant, wherein a substantial portion of
said first evaporator tube section (21) is arranged generally in
parallel with said partition wall (11), and wherein said
substantial portion of the first tube section (21) includes two
non-coaxial tube portions (21a), the axes of said tube portions
together defining a general extension plane of said substantial
portion of the first evaporator section, said general extension
plane being arranged generally in parallel with said partition wall
(11).
2. (cancelled)
3. Refrigerator according to claim 1, wherein the general extension
plane of the substantial portion of the first evaporator tube
section (21) is arranged generally parallel to and closer to the
partition wall (11) than to each of said outer walls.
4. Refrigerator according to a claim 1 or 3, wherein said first
wall (2) is a rear wall being arranged opposite to the door (7,8)
and said partition wall (11) is extending in parallel with a
generally vertical plane between the back wall (2) and the door
(7,8).
5. Refrigerator according to claim 1 or 3 wherein said substantial
portion of said first evaporator tube section (21) is arranged
adjacent a surface said partition wall (11), said surface of said
partition wall facing the low temperature storage compartment
(9).
6. Refrigerator according to a claim 1 or 3, wherein a gap (33) is
formed between said substantial portion of said first evaporator
tube section (21) and said partition wall (11).
7. Refrigerator according to claim 1 or 3, wherein said substantial
portion of said first evaporator tube section (21) is arranged at
least partly within said partition wall (11).
8. Refrigerator according to claim 1 or 3, wherein said first
evaporator tube section (21) is provided with heat transferring
flanges (34).
9. Refrigerator according to claim 1 or 3, wherein said second
evaporator tube section (22) is arranged generally in parallel with
said first wall (2).
10. Refrigerator according to claim 1 or 3, wherein said second
evaporator section (22) is arranged generally in parallel with the
partition wall (11), at an opposite side of the partition wall from
the first evaporator tube section (21).
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
essentially sealed from each other and separated by a partition
wall, which partition wall is arranged inside the cabinet and
generally perpendicular to a first wall of said outer walls, and an
absorption refrigerating system including an evaporator tube having
a first evaporator tube section for cooling the low temperature
compartment and a second evaporator tube section for cooling the
higher temperature compartment, said second evaporator tube section
being arranged downstream said first evaporator tube section.
BACKGROUND OF THE INVENTION
[0002] Absorption refrigerators have been commonly used in e.g.
recreation vehicles and mobile homes for a long time. More
recently, so called side-by-side absorption refrigerators have been
increasingly popular also in such mobile applications. In
side-by-side refrigerators a freezing compartment and a food
storage compartment, which is kept at a higher temperature, are
arranged vertically side by side and separated by a vertical
partition wall. The evaporator tube is normally arranged in or at
the rear wall of the refrigerator cabinet. The evaporator has a
first freezer section, which extends in or at an interior surface
of a portion of the rear wall, which portion covers the freezer. A
second downstream section of the evaporator is arranged to cool the
higher temperature compartment and extends in or at an interior
surface of a portion of the rear wall, which portion covers the
higher temperature compartment.
[0003] A problem with this type of absorption refrigerator cabinets
is a considerable heat transfer through the rear wall from the
outside of the cabinet to the inside. Such inwardly directed heat
transfer is driven by the difference in temperatures between the
outside and the inside of the cabinet. Therefore, the heat transfer
through the surrounding walls is particularly high into the freezer
compartment. The freezer section of the evaporator is the coldest
section of the evaporator. Since the freezer section is arranged in
or at the rear wall of the freezer compartment, this freezer rear
wall will have the lowest temperature of all the walls surrounding
the refrigerator cabinet. Thus, the difference in temperature
between the surrounding atmosphere and the inside of the cabinet
walls is greatest at the rear freezer wall. Therefore, heat
transfer into the cabinet is also greatest through the rear wall of
the freezer compartment, near to the freezer section of the
evaporator.
[0004] Heat transfer into the refrigerator cabinet is particularly
disadvantageous at absorption refrigerators used in mobile
applications. At absorption refrigerators, the physical dimensions
of the refrigeration system limit the maximum cooling capacity.
This makes it difficult to keep the respective compartments at the
desired temperature. This problem is particularly severe for the
freezer compartment, for which, at modern mobile refrigerators, it
is desired to keep the temperature as low as -18.degree. C. Any
heat which is added into the cabinet is therefore most undesirable
and often causes the temperature in the freezer to raise above the
desired value. This in turn deteriorates the quality of foodstuff
stored in the freezer or reduces the maximum possible storage
time.
[0005] A further problem with the above-described known
refrigerator is that the time required for lowering the freezer
temperature from the starting temperature to the desired freezer
temperature at start up of the system (so called "pull-down") is
relatively long. This is partly caused by the fact that the freezer
section of the evaporator is arranged in or at one of the outer
walls of the cabinet. The insulation inside the outer walls has to
be comparatively thick and it contains a considerable amount of
heat, which is absorbed by the evaporator during the initial
temperature reduction in the freezer compartment. Considerable
cooling capacity of the refrigeration system is thus used for
absorbing heat from the outer wall instead of the air inside the
freezer compartment, whereby the pull-down time is extended.
BRIEF DESCRIPTION OF THE INVENTION
[0006] It is an objective of the present invention to provide an
absorption refrigerator at which the cooling capacity of the
refrigerating system is more efficiently used for keeping the items
stored in the cabinet at the desired temperature.
[0007] It is a further object to provide an absorption refrigerator
at which the heat transfer through the surrounding walls into the
cabinet is reduced.
[0008] A further object is to provide an absorption refrigerator at
which the heat transfer particularly into the freezer compartment
is reduced.
[0009] A still further object is to provide an absorption
refrigerator at which the time needed for lowering the freezer
temperature to the desired temperature at start up is reduced.
[0010] These and other objects are achieved by a refrigerator
according to the first paragraph of this description at which a
major part of said first evaporator tube section is arranged
generally in parallel with said partition wall.
[0011] By such an arrangement of that section of the evaporator,
which absorbs heat from the freezer compartment, it is assured that
at least the major part of this section is arranged at a distance
from the rear walls. Thereby, the major part of the freezer
evaporator predominantly absorbs heat from the air in the freezer
compartment and no superfluous cooling of the outer walls is
caused. The outer walls thus remain at a higher temperature,
whereby heat transfer from the surrounding atmosphere through the
outer walls is reduced. The reduction of heat absorbed from the
outer walls also reduces the time for lowering the freezer
temperature at start-up. Also when the freezer section of the
evaporator is arranged in or in the proximity of the dividing wall,
the pull-down time is reduced since the heat contained in the
dividing wall at start-up is considerably less than that in the
outer walls, due to thinner insulation. Further more, such
placement of the freezer section contributes to lowering the
temperature in the higher temperature compartment, on the other
side of the dividing wall.
[0012] Further objects and advantages of the invention are set out
in the depending claims. According to one embodiment, the partition
wall is arranged as a vertical wall extending between the outer
rear wall and the front door or doors. Thereby, the invention is
advantageously applied to a modern side-by-side refrigerator. The
second section of the evaporator, which cools the higher
temperature compartment, may be arranged in parallel with the rear
wall. This may be advantageous for space saving or tube bending
purposes and such placement of the second section of the evaporator
does not to the same extent contribute to the heat transfer into
the higher temperature compartment, since this evaporator section
is kept at a higher temperature. The freezer section of the
evaporator may be arranged in parallel to, and in proximity to the
partition wall. Hereby, a gap may be arranged between the
evaporator freezer section and the partition wall. Such a gap
allows for air to freely circulate around the freezer evaporator
section, which enhances heat transfer from the air in the freezer
compartment to the evaporator. Further more, such a gap prevents
that the freezer evaporator absorbs heat from the partition wall,
whereby the system is more efficiently used for cooling the air and
items stored in the freezer compartment. This also contributes to
reduce the pull-down time even further. The freezer section of the
evaporator may also be arranged entirely or partly in the dividing
wall, whereby the space requirement for the evaporator inside the
freezer cabinet is reduced. In order to further enhance the heat
transfer from the air to the evaporator, at least a portion of the
evaporator may be provided with heat transferring flanges.
DETAILED DESCRIPTION OF THE INVENTION
[0013] An exemplifying embodiment of the invention will now be
described with reference to the accompanying drawings in which:
[0014] FIG. 1 is a top elevation view, with parts of the walls
broken away, of a refrigerator cabinet according to the present
invention.
[0015] FIG. 2 is a perspective view from behind, with parts broken
away, of the refrigerator in FIG. 1.
[0016] 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 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, 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.
[0017] 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.
[0018] For cooling the two compartments 9, 11, 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. The two evaporator sections
21 and 22 are connected through a passive section 23, which is
embedded in the insulation of the rear wall 2. This passive section
23 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.
[0019] 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.
[0020] The first evaporator tube section 21 is arranged immediately
downstream of the upstream end 24 of the evaporator. The first
evaporator section 21 is formed by four generally straight tube
sections 21a, which are connected, one after the other through
three tube bends 21b. The straight tube sections 21a and the tube
bends 21b are arranged vertically, one over the other, generally in
the same vertical plane. 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 first evaporator section, the first
evaporator section 21 is connected to the passive evaporator
section 23. The passive section 23 extends inside the rear wall 2
at a slight downward slope, past the partition wall 11 and 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 32 is
connected to the absorber of the refrigerating apparatus (not
shown).
[0021] During normal operation, the temperature of the
refrigerating medium in the evaporator is typically maintained at
approx. -30.degree. C. at the upstream end 24 of the first
evaporator section. At the downstream end 29 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 passive evaporator section 23, the temperature increases due to
absorption of heat from the adjacent conduits 25, 26, whereby the
temperature at the upstream end of the second evaporator section is
about -18.degree. C. During passage through the second evaporator
section 22 the coolant temperature is typically raised to approx.
-14.degree. C.
[0022] As can be seen from the figures, the first evaporator
section 21 is arranged such that the evaporator tube 21a, 21b of
this section 21 forms a vertical general extension plane of the
section, which plane is defined by the logidudinal axis of the four
evaporator tube portions 21a. The first evaporator section 21 is
further arranged inside the freezer compartment 9, in the upper
half of this compartment 9. The first evaporator section 21 is also
arranged such that its general extension plane lies in parallel
with the vertical extension plane of the partition wall 11.
Further, the first evaporator section 21 is arranged at a small
distance from the surface of the partition wall, which surface
faces the freezer compartment 9, such that a gap 33 is formed
between the partition wall 9 and the first evaporator section 21.
For enhancing the heat transfer from the air in the freezer
compartment 9 to the first evaporator section 21, a flanged baffle
element 34 of a heat conducting material is attached to the first
evaporator section. The baffle element 34 exhibits a generally
comb-shaped transverse section and includes a base and a plurality
of flanges having a vertical longitudinal direction. In the shown
embodiment, one baffle element 34 is arranged on the side of the
first evaporator section 21, which side faces away from the gap 33
and the partition wall 11. However, it is also contemplated that
one or several flanged baffle elements other heat transferring
means could be attached to either or both sides of the first
evaporator section 21.
[0023] By the arrangement of the first evaporator section 21
described above it is accomplished that, during operation of the
refrigerating system, the freezer evaporator section 21
predominantly absorbs heat from the air in the freezer compartment
9 and not directly from any of the surrounding walls 2-6, the doors
7, 8 or the partition wall 11. Hereby, the outer walls 2-6 and the
doors 7, 8 are not superfluously cooled. The heat transfer into the
freezer compartment through the outer walls and doors, which is
driven by the temperature difference between the inner and outer
surfaces of the outer walls and doors, is therefore maintained at a
minimum.
[0024] The gap 33 allows for air to circulate around the first
evaporator section 21, which enhances the heat transfer from the
coolant fluid inside the first evaporator section.
[0025] In the higher temperature refrigerator compartment 10, the
second evaporator section 22 is arranged in an analogue manner. In
the shown embodiment however, the longitudinal directions of the
two second evaporator tube portions 22a define a vertical general
plane of extension, which is arranged in parallel with the rear
wall 2. Since the second evaporator section is maintained at a
considerably higher temperature than the first evaporator section
9, such an arrangement does not adversely contribute to any
significant heat transfer into the higher temperature compartment
10, through the rear wall 2. Also the second evaporator section 22
is arranged at a gap-forming distance from the rear wall and
provided with a flanged baffle element 35 on its side facing away
from the gap 36 and rear wall 2.
[0026] 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 at a distance
from the dividing wall, the first evaporator section, or a part
thereof, may be arranged on the surface of freezer compartment side
of the partition wall. The whole or a part of the first evaporator
section may also be arranged inside the partition wall. In such a
case, a part of the transverse section of the first evaporator tube
section may be arranged to project from the partition wall into the
freezer compartment. Alternatively, the first evaporator tube
section may be entirely arranged inside the partition wall, whereby
heat transferring means, such as flanges, preferably are arranged
in thermal contact with the first evaporator tube section and
projecting into the freezer compartment.
[0027] Also the arrangement of the second evaporator section may be
varied in a number of different ways. For instance, instead of
being arranged in parallel with the rear wall, it may be arranged
in parallel with the partition wall, at that side of the partition
wall, which faces the higher temperature refrigerator compartment.
In both cages, also the second evaporator section may be arranged
at a distance from the partition wall, on the partition wall
surface or inside the partition wall, as described for the first
evaporator section above.
[0028] Both the first and second evaporator sections may have other
tube configurations than the ones described above. They 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.
[0029] In the above-illustrated embodiment, the partition wall
hermetically seals off 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.
* * * * *