U.S. patent application number 11/993147 was filed with the patent office on 2010-02-25 for refrigerator or freezer with enhanced efficiency.
Invention is credited to Alfred P. Brunger, Mark A. Fleming.
Application Number | 20100043463 11/993147 |
Document ID | / |
Family ID | 37595022 |
Filed Date | 2010-02-25 |
United States Patent
Application |
20100043463 |
Kind Code |
A1 |
Fleming; Mark A. ; et
al. |
February 25, 2010 |
REFRIGERATOR OR FREEZER WITH ENHANCED EFFICIENCY
Abstract
A refrigerator or a freezer comprises a primary refrigeration
system (11) which is augmented with a passive secondary
refrigeration loop (15) having a condenser (30) in thermal contact
with a primary fluid line (12) at the location between a primary
compressor (16) and a primary condenser (18) and preferably placed
outside a building so that the passive secondary refrigeration loop
(15) provides cooling to the primary refrigeration system (11) when
the outside temperature is sufficiently low The condenser (30) of
the passive secondary refrigeration loop (15) is positioned above
the points where the primary fluid line (12) connects with mlet
(32) and outlet (34) lines of the secondary loop condenser (30)
Inventors: |
Fleming; Mark A.; (Toronto,
CA) ; Brunger; Alfred P.; (Waterloo, CA) |
Correspondence
Address: |
SMART & BIGGAR
438 UNIVERSITY AVENUE, SUITE 1500, BOX 111
TORONTO
ON
M5G 2K8
CA
|
Family ID: |
37595022 |
Appl. No.: |
11/993147 |
Filed: |
June 22, 2006 |
PCT Filed: |
June 22, 2006 |
PCT NO: |
PCT/CA2006/001042 |
371 Date: |
December 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60694134 |
Jun 27, 2005 |
|
|
|
Current U.S.
Class: |
62/113 ; 62/498;
62/513 |
Current CPC
Class: |
F25B 40/04 20130101;
F25B 6/04 20130101; F25D 23/003 20130101 |
Class at
Publication: |
62/113 ; 62/513;
62/498 |
International
Class: |
F25B 41/00 20060101
F25B041/00; F25B 1/00 20060101 F25B001/00 |
Claims
1. A refrigerator or freezer comprising: a primary refrigeration
circuit having a circuit condenser, a circuit evaporator, a circuit
compressor, and a circuit fluid line defining a loop which fluidly
connects said circuit evaporator to said circuit condenser through
said circuit compressor such that said circuit compressor draws
refrigerant in said circuit fluid line from said circuit evaporator
and pumps said refrigerant toward said circuit condenser; a passive
refrigeration loop or spur comprising a loop or spur condenser; a
loop or spur line fluidly communicating with a lower portion of
said loop or spur condenser; said loop or spur line associated with
said fluid line between an outlet of said evaporator and an inlet
of said condenser at a location below said loop or spur
condenser.
2. The refrigerator or freezer of claim 1 wherein said loop or spur
line is associated with said circuit line between said circuit
compressor and said circuit condenser.
3. The refrigerator or freezer of claim 1 wherein said loop or spur
line is associated with said circuit line at an outlet of said
circuit compressor.
4. The refrigerator or freezer of claim 1 wherein said passive
refrigeration loop or spur is a loop, said loop or spur condenser
is a loop condenser, and said loop or spur line is a loop outlet
line and further comprising a loop inlet line extending to an upper
portion of said loop condenser, said loop inlet line associated
with said circuit line between an outlet of said circuit evaporator
and an inlet of said circuit condenser, said loop outlet line
associated with said circuit line downstream of said loop inlet
line.
5. The refrigerator or freezer of claim 4 wherein said loop inlet
line is associated with said circuit line between said circuit
compressor and said circuit condenser.
6. The refrigerator or freezer of claim 4 wherein said loop inlet
line is associated with said circuit line at an outlet of said
circuit compressor.
7. The refrigerator or freezer of any one of claim 4 to claim 6
claim 4 wherein said loop inlet line and said loop outlet line are
fluidly connected at said circuit line through a loop heat
exchanger in heat exchange relation with said circuit line.
8. The refrigerator or freezer of claim 7 wherein said loop heat
exchanger is a spiral tube, one end of which is in fluid
communication with said loop outlet line and another end of which
is in fluid communication with said loop inlet line, said spiral
tube being wound around said circuit line.
9. The refrigerator or freezer of claim 4 wherein said loop inlet
line is tapped into said circuit line and wherein said loop outlet
line is tapped into said fluid line downstream of said loop inlet
line.
10. The refrigerator or freezer of claim 1 wherein said compressor
is a positive displacement compressor.
11. The refrigerator or freezer of claim 1 further comprising a
shield positioned for shading said loop or spur condenser from
sun.
12. The refrigerator or freezer of claim 4 further comprising a
shield positioned for shading said loop condenser from sun.
13. The refrigerator or freezer of claim 1 further comprising a
circuit expansion valve between an outlet of said circuit condenser
and an inlet of said circuit evaporator.
14. The refrigerator or freezer of claim 1 wherein said loop or
spur line functions as a loop or spur inlet line and a loop or spur
outlet line.
15. A refrigerator or freezer, comprising: a closed primary
refrigeration system; a closed secondary, passive, refrigeration
circuit; said secondary refrigeration circuit having a heat
exchanger in heat exchange relation with said primary refrigeration
system, said secondary passive refrigeration circuit being one of a
heat pipe loop and a thermosiphon loop.
16. A method of enhancing efficiency of a refrigerator or freezer,
comprising: positioning a heat exchanger of a passive refrigeration
loop having said heat exchanger and a passive loop condenser in
heat exchange relation with a waste heat bearing element of a
primary refrigeration system of said refrigerator or freezer;
positioning said passive loop condenser outside a building housing
said refrigerator or freezer such that said passive loop condenser
is exposed to ambient temperature, said passive loop condenser
positioned above said heat exchanger.
17. The method of claim 16 wherein said passive refrigeration loop
is one of a heat pipe loop and a thermosiphon loop.
18. The method of claim 16 wherein said passive refrigeration loop
is a heat pipe loop, said heat pipe loop comprising a heat pipe
line fluidly connecting said heat exchanger with a lower portion of
said passive loop condenser.
19. The method of claim 18 wherein said heat pipe line is a heat
pipe outlet line and further comprising a heat pipe inlet line
fluidly connected to said heat pipe outlet line through said heat
exchanger, said heat pipe inlet line in fluid communication with
said passive loop condenser.
20. The method of claim 16 wherein said heat exchanger is a tube
and wherein said positioning said heat exchanger comprises winding
said tube around said waste heat bearing element.
21. The method of claim 16 wherein said primary refrigeration
system comprises a primary circuit condenser, a primary circuit
evaporator, a primary circuit compressor, and a fluid line defining
a loop which fluidly connects said primary circuit evaporator to
said primary circuit condenser through said primary circuit
compressor such that said primary circuit compressor draws
refrigerant in said fluid line from said primary circuit evaporator
and pumps said refrigerant toward said primary circuit condenser,
said positioning said heat exchanger comprising positioning said
heat exchanger at said fluid line between an outlet of said primary
circuit evaporator and an inlet of said primary circuit
condenser.
22. The method of claim 21 wherein said positioning said heat
exchanger comprises positioning said heat exchanger at said fluid
line between said primary circuit compressor and said primary
circuit condenser.
23. The method of claim 22 wherein said positioning said heat
exchanger comprises positioning said heat exchanger at said fluid
line at an outlet of said primary circuit compressor.
24. The method of claim 16 further comprising shielding said
passive loop condenser from sun.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of prior
provisional application Ser. No. 601694,134, filed Jun. 27, 2005,
the contents of which are hereby incorporated herein by
reference.
BACKGROUND
[0002] This invention relates to a refrigerator or freezer and to a
method of enhancing the efficiency of a refrigerator or
freezer.
[0003] Known vapour compression refrigerators, including domestic
refrigerators, have a refrigerant filled fluid line which defines a
loop incorporating, in fluid flow order, an evaporator, a
compressor, a condenser, and an expansion valve. The evaporator is
associated with a cavity to be cooled. The condenser has a heat
exchanger, typically in the air flow path of a fan, to dissipate
heat. The refrigerant may be a low boiling point liquid, such as a
hydroflurocarbon. In operation, the compressor draws gaseous
refrigerant in the fluid line from the evaporator and pumps the
refrigerant toward the condenser. The high pressure in the
condenser and the cooling resulting from the heat exchanger and fan
liquifies the refrigerant. Cooled liquid refrigerant leaving the
condenser passes through the expansion valve and enters the
evaporator where it may vaporise by drawing heat from the cavity to
be cooled.
[0004] A typical domestic refrigerator consumes 390 to 650 kilowatt
hours per year and a typical commercial refrigerator consumes
considerably more energy than a domestic refrigerator. These
refrigerators throw off waste heat into the room in which they are
housed. It would be advantageous to reduce the power consumption of
refrigerators.
SUMMARY OF INVENTION
[0005] The primary refrigeration system of a refrigerator or
freezer is augmented with a passive refrigeration loop or spur
which has a condenser that may be placed outside so that the
passive loop or spur cools provides cooling to the primary
refrigeration system when the outside temperature is sufficiently
low.
[0006] A refrigerator or freezer may have a primary refrigeration
circuit with a circuit condenser, a circuit evaporator, a circuit
compressor, and a circuit fluid line defining a loop which fluidly
connects the circuit evaporator to the circuit condenser through
the circuit compressor such that the circuit compressor draws
refrigerant in the circuit fluid line from the circuit evaporator
and pumps the refrigerant toward the circuit condenser. In an
aspect of the invention, a passive refrigeration loop or spur is
added. The loop or spur has a loop or spur condenser and a loop or
spur line fluidly communicating with a lower portion of the loop or
spur condenser. The loop or spur line is associated with the fluid
line of the active circuit between an outlet of the circuit
evaporator and an inlet of the circuit condenser at a location
below the loop or spur condenser.
[0007] According to another aspect of the invention, there is
provided a refrigerator or freezer, comprising: a closed primary
refrigeration system; a closed secondary, passive, refrigeration
circuit; said secondary refrigeration circuit having a heat
exchanger in heat exchange relation with said primary refrigeration
system, said secondary passive refrigeration circuit being one of a
heat pipe loop and a thermosiphon loop.
[0008] According to a further aspect of the invention, there is
provided a method of enhancing efficiency of a refrigerator or
freezer, comprising: positioning a heat exchanger of a passive
refrigeration loop having said heat exchanger and a passive loop
condenser in heat exchange relation with waste heat bearing element
of a primary refrigeration system of said refrigerator or freezer;
positioning said passive loop condenser outside a building housing
said refrigerator or freezer such that said passive loop condenser
is exposed to ambient temperature, said passive loop condenser
positioned above said heat exchanger.
[0009] Other features and advantages will become apparent from a
review of the detailed description in conjunction with the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] In the figures which illustrate example embodiments of the
invention,
[0011] FIG. 1 is a schematic view of a refrigerator made in
accordance with this invention,
[0012] FIG. 1A is a schematic view of a portion of a refrigerator
made in accordance with another embodiment of this invention,
[0013] FIG. 2 is a schematic view of a portion of a refrigerator
made in accordance with another embodiment of this invention,
[0014] FIG. 2A is a schematic view of a portion of a refrigerator
made in accordance with another embodiment of this invention,
and
[0015] FIG. 3 is a schematic view of a portion of a refrigerator
made in accordance with another embodiment of this invention.
DETAILED DESCRIPTION
[0016] Turning to FIG. 1, a refrigerator 10 may have a primary
refrigeration circuit 11 located inside a building 50 and a
secondary (passive) refrigeration loop 15 located at least
partially outside building 50. The primary refrigeration circuit 11
may be a vapour compression circuit with a refrigerant filled fluid
line 12 which defines a loop incorporating, in fluid flow order, an
evaporator 14, a compressor 16, a condenser 18, and an expansion
valve 20. The evaporator may be associated with a cavity 22 to be
cooled. The circuit's condenser 18 may have a heat exchanger 24 in
the air flow path of a fan 26.
[0017] The secondary passive refrigeration loop 15 may have a
condenser 30 located outside building 50 coupled in parallel to
fluid line 12 through a loop inlet line 32 extending from fluid
line 12 (through a wall of the building) to an upper portion of the
loop's condenser 30 and a loop outlet line 34 extending from a
lower portion of the loop's condenser (through a wall of the
building) to fluid line 12. Normally the outlet line will be
connected to the lowermost part of the loop's condenser which, in
the embodiment of FIG. 1, is the bottom of the loop's condenser.
The loop inlet and outlet lines 32, 34 are connected to the fluid
line 12 between the outlet 40 of the circuit's compressor 16 and
the inlet 38 of the circuit's condenser 18, with the loop outlet
line connected to fluid line 12 downstream of the loop inlet line
(where the downstream direction D is defined by the direction of
refrigerant flow in line 12). The loop outlet line 34 terminates at
the fluid line 12 below the level of the loop's condenser.
Optionally, the loop's inlet line 32 also terminates at fluid line
12 below the level of the loop's condenser, or at least below the
level of the upper portion of the loop's condenser.
[0018] A shield 54 may be disposed around the loop's condenser 30
to shield the heat pipe from the sun.
[0019] The refrigerant may be a low boiling point liquid, such as a
hydroflurocarbon. The compressor may be a positive displacement
compressor such as a compressor with a piston to draw refrigerant
in from the evaporator on a down stroke and expel it toward the
compressor on an upstroke.
[0020] In operation, the compressor draws gaseous refrigerant in
the fluid line from the evaporator and pumps the refrigerant toward
the condenser. Some of the gaseous refrigerant pumped by the
compressor travels through loop inlet line 32 to the upper portion
of the loop's condenser 30. If the ambient air outside building 50
is sufficiently cold, this refrigerant will condense to liquid
which will be gravity fed down the loop's condenser 30 and down the
loop outlet line 34 back to the fluid line 12. In consequence, a
portion of the refrigerant in the fluid line between the compressor
and the condenser is condensed to liquid. This reduces the pressure
at the outlet of the compressor, thereby reducing the back pressure
on the compressor and, in consequence, the load on the compressor.
Hence the power required by the condenser to operate is
reduced.
[0021] The cooler refrigerant then enters the condenser. The
pressure in the condenser and the cooling resulting from the heat
exchanger and fan liquifies remaining gaseous refrigerant. Cooled
liquid refrigerant leaving the condenser passes through the
expansion valve and enters the evaporator where it may vaporise by
drawing heat from the cavity to be cooled.
[0022] Refrigerant will travel through the loop 15 whenever the
temperature at the loop condenser 30 is less than the refrigerant
temperature at the point where the loop inlet line 32 joins fluid
line 12. The refrigerant temperature at the outlet 36 of the
circuit evaporator 14 will typically be close to the temperature in
cavity 22. Consequently, if the outdoor temperature is expected to
be less than the temperature in cavity 22, the loop inlet and
outlet lines could join to the fluid line 12 between the outlet 36
of the evaporator and the inlet of the compressor 16. However, the
efficiency of the passive refrigeration loop 15 is directly
proportional to the differential between the temperature of
refrigerant where the loop inlet 32 joins fluid line 12 and the
temperature at the loop condenser 30. Thus, while the heat pipe
inlet may be positioned anywhere between the outlet of the
circuit's evaporator and the inlet of the circuit's condenser, it
is advantageously positioned at the outlet of the compressor. This
is for the reason that this is the location in fluid line 12 where
the refrigerant is the hottest (due to the heat of compression,
which is about 50.degree. C. in a domestic refrigerator) and so
cooling such refrigerant maximizes the reduction in the load on the
compressor.
[0023] The shield about the loop's condenser reduces solar heating
of the loop's condenser.
[0024] If the ambient temperature is too high to allow gaseous
refrigerant in the loop's condenser 30 to condense, as more gaseous
refrigerant enters the loop's condenser, the vapour pressure in the
loop's condenser will rise to the pressure in fluid line 12. At
this point, no further gaseous refrigerant will migrate into the
loop's condenser and refrigerant in line 12 will simply by-pass the
loop's condenser. This situation will continue until the ambient
temperature drops to a point where refrigerant begins to condense
in the loop's condenser. The result is that the loop's condenser
acts as a thermal diode, naturally shutting down when ambient
temperatures are too high to allow refrigerant to condense, and
naturally turning on again whenever ambient temperatures drop
sufficiently to result in refrigerant condensing in the loop's
condenser. Of course the lower the ambient temperature, the more
quickly refrigerant will condense in the loop's condenser and,
hence, the greater the efficiency increase provided by the passive
refrigeration loop.
[0025] FIG. 1A illustrates a modification where, rather than having
a passive refrigeration loop, a passive refrigeration spur is used.
That is, in place of a loop inlet line and outlet line there is
simply one loop line 156 which is connected between the bottom of
the spur condenser 30 and the fluid line 12 at the outlet 40 of the
compressor 16.
[0026] The operation is similar to what has been described in
conjunction with FIG. 1 except that gasous refrigerant at the
outlet of the compressor flows up into the spur condenser through
line 156 and, after condensing in the spur condenser, flows back
down line 156 to fluid line 12.
[0027] Turning to FIG. 2, in another embodiment, the loop outlet
line is joined to the loop inlet line at fluid line 12 through a
heat exchanger/evaporator 260. The condenser 30 of the loop is
positioned above the heat exchanger 260. As illustrated in FIG. 2,
the heat exchanger may simply be a spiral tube which is wound
around the fluid line 12 with one end of the tube joined to the
loop outlet line 234 and the other end of the tube joined to the
loop inlet line 232. Additionally, the portion of the loop outlet
line within the building 50 may be insulated by insulation barrier
258 to avoid unnecessary heating of condensed refrigerant and the
portion of the loop inlet line within building 50 may be insulated
by insulation barrier 259 to avoid condensation of refrigerant in
the upward-sloping loop inlet line, which condensation may present
a barrier to the upward flow of refrigerant vapour.
[0028] In this embodiment, the loop inlet line 232, loop condenser
30, heat pipe outlet line 234 and heat exchanger/evaporator 260
form a closed heat pipe loop 211 which is isolated from
refrigeration circuit 11. The isolated refrigeration loop 211 may
be partially filled with any suitable phase change refrigerant,
such as a hydroflurocarbon refrigerant. The refrigerant in circuit
211 may be termed the second refrigerant.
[0029] In operation, hot refrigerant in fluid line 12 at the outlet
of compressor passes through heat exchanger/evaporator 260. The
cool second refrigerant in heat exchanger/evaporator 260 absorbs
heat from the hot refrigerant in the fluid line 12 and, in
consequence, is heated. The heating of the second refrigerant
causes it to vaporise and migrate into loop condenser 30. In the
loop condenser, the second refrigerant is cooled and condenses. The
condensed refrigerant flows back down to the heat exchanger
260.
[0030] As is apparent from FIG. 2, the loop outlet line 234, which
has the coldest fluid from the passive loop, is joined to the end
of the heat exchanger furthest from the compressor 16. In a
modification shown in FIG. 2A, it is the loop inlet line 232' which
is joined to the end of the heat exchanger 260 furthest from the
compressor 16. The set-up of FIG. 2 is believed to be more
efficient as the refrigerant leaving the compressor is exposed to
increasingly cold temperatures from the coldest heat exchanger of
the passive loop.
[0031] Where a closed passive refrigeration loop is employed,
rather than partially filling the passive circuit with a liquid
phase change refrigerant, the circuit can be completely filled with
a liquid refrigerant, which may or may not be a phase change
refrigerant. With the circuit completely filled with refrigerant,
the circuit acts as a thermosiphon loop rather than as a heat pipe
loop. More specifically, when the second refrigerant is heated in
heat exchanger 260, it become less dense and convectively flows
upwardly along line 232 toward condenser 30. In condenser 30, the
refrigerant cools, becomes more dense and flows downwardly along
line 234 back to the heat exchanger. An exemplary non-phase change
refrigerant is ethanol.
[0032] The condenser 30 of any of the embodiments may simply be a
hollow pipe which is vertically oriented, or which declines at an
acute angle from the vertical. Alternatively, the hollow pipe
condenser, the loop outlet line and the evaporator/heat exchanger
may be lined with wicks. In such instance, and where these elements
are part of an isolated refrigerant loop (as, for example, in
either of the embodiments of FIG. 2 or FIG. 2A), and where the
isolated loop acts as a heat pipe loop, another embodiment is
available. Specifically, the condenser 30 may be horizontally
oriented. This embodiment is illustrated in FIG. 3. Turning to FIG.
3, loop condenser 330 of passive refrigeration loop 311 is a
horizontally oriented pipe lined with wicks 370. The loop inlet 332
may communicate to any part of the condenser 330. The loop outlet
334, also lined with wicks, may communicate with the condenser
anywhere along its bottom wall. With this embodiment, when gaseous
refrigerant enters the condenser 330 and condenses, it is absorbed
by the wicks lining the walls of the heat pipe. There is a low
pressure in the heat exchanger/evaporator 260 which draws liquid
refrigerant along the wicks. The wicks therefore become drier in
heat exchanger than elsewhere. The consequence is that liquid
refrigerant in the wicks is drawn by capillary action toward the
heat exchanger and the process continues.
[0033] To increase the heat transfer rate of the condenser 30 or
330, it could be provided with heat exchange fins.
[0034] With the embodiments of any of FIGS. 2, 2A, or 3,
optionally, the mass of heat exchanger 260 may be made sufficiently
large so that the heat exchanger is a thermal store. In this
instance, whenever the active refrigeration circuit is inactive,
the passive refrigeration loop will continue to operate while the
temperature of the heat exchanger 260 remains higher than the
ambient temperature of the loop condenser 30 (or 330). Over time,
this lowers the temperature of the thermal store heat exchanger
260. In consequence, when the active refrigeration circuit turns
on, the relatively cold thermal store heat exchanger will act to
cool refrigerant in line 12 for a period of time.
[0035] While in the example embodiments the primary refrigeration
cycle is a vapour compression cycle, it will be apparent to those
skilled in the art that the teachings of this invention have
application to refrigeration systems where the primary
refrigeration cycle is of some other type. More specifically, the
isolated refrigeration loops described in conjunction with FIGS. 2
and 3 may be used to draw heat from a waste heat bearing element in
any type of primary refrigeration system And the refrigeration loop
and spur of FIGS. 1 and 1A may be used to draw heat from a waste
heat bearing fluid line in any primary refrigeration system having
such line to tap into provided no non-condensable gas will be
trapped. For example, the heat exchanger of the isolated
refrigeration loops of FIGS. 2 and 3 could be associated with the
condenser or absorber of an absorber refrigeration system, the hot
plate of a thermoelectric refrigeration system, or the heat
exchanger of a thermo-acoustic refrigeration system. And the
refrigeration loop or spur of FIGS. 1 and 1A may be tapped into the
condenser of an absorber refrigeration circuit.
[0036] While the example embodiments have been described in
conjunction with a refrigerator, equally the refrigerator may be a
freezer.
[0037] Other variations will be apparent to those skilled in the
art and, therefore, the invention is defined in the claims.
* * * * *