U.S. patent application number 11/908623 was filed with the patent office on 2008-08-07 for bottle cooler defroster and methods.
This patent application is currently assigned to CARRIER COMMERCIAL REFRIGERATION, INC.. Invention is credited to Yu Chen, Hans-Joachim Huff, Tobias H. Sienel, Parmesh Verma.
Application Number | 20080184715 11/908623 |
Document ID | / |
Family ID | 37024109 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080184715 |
Kind Code |
A1 |
Chen; Yu ; et al. |
August 7, 2008 |
Bottle Cooler Defroster And Methods
Abstract
A bottle cooler system (20, 70, 100) includes a compressor (22),
a first heat exchanger (24) and a second heat exchanger (28). In a
cooling mode of operation, the second heat exchanger is downstream
of the first heat exchanger and upstream of the compressor to cool
contents of an interior volume. In a defrost mode of operation,
refrigerant in the second heat exchanger is used to defrost an ice
build-up on the second heat exchanger.
Inventors: |
Chen; Yu; (East Hartford,
CT) ; Sienel; Tobias H.; (East Hampton, MA) ;
Verma; Parmesh; (Manchester, CT) ; Huff;
Hans-Joachim; (West Hartford, CT) |
Correspondence
Address: |
BACHMAN & LAPOINTE, P.C. (UTC)
900 CHAPEL STREET, SUITE 1201
NEW HAVEN
CT
06510-2802
US
|
Assignee: |
CARRIER COMMERCIAL REFRIGERATION,
INC.
Charlotte
NC
|
Family ID: |
37024109 |
Appl. No.: |
11/908623 |
Filed: |
December 30, 2005 |
PCT Filed: |
December 30, 2005 |
PCT NO: |
PCT/US2005/047529 |
371 Date: |
September 14, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60663961 |
Mar 18, 2005 |
|
|
|
Current U.S.
Class: |
62/81 ; 62/160;
62/234; 62/246; 62/278 |
Current CPC
Class: |
F25B 2700/21173
20130101; F25B 2309/061 20130101; F25B 13/00 20130101; F25D
2331/803 20130101; F25D 31/007 20130101; F25B 2700/21175 20130101;
F25B 47/025 20130101; F25B 9/008 20130101; F25B 47/022 20130101;
F25D 19/02 20130101 |
Class at
Publication: |
62/81 ; 62/234;
62/160; 62/246; 62/278 |
International
Class: |
F25B 47/02 20060101
F25B047/02; F25B 41/04 20060101 F25B041/04; F25D 21/06 20060101
F25D021/06; F25D 11/00 20060101 F25D011/00; F25B 49/02 20060101
F25B049/02; F25D 29/00 20060101 F25D029/00; A47F 3/04 20060101
A47F003/04; F25B 13/00 20060101 F25B013/00 |
Claims
1. A cooler system (20; 70; 100) comprising: a compressor (22) for
driving a refrigerant along a flowpath (32; 72; 100, 112) in at
least a first mode of system operation; a first heat exchanger (24)
along the flowpath (32; 72; 100, 112) downstream of the compressor
(22) in the first mode; a second heat exchanger (28) along the
flowpath (32; 72; 100, 112) upstream of the compressor (22) in the
first mode to cool contents of an interior volume of the system;
and means (50; 78; 102) for defrosting an ice buildup on the second
heat exchanger using refrigerant in the second heat exchanger.
2. The system of claim 1 wherein the means comprises: a controller
(50) programmed or configured to run a first fan (40) to drive a
first air flow (44) across the first heat exchanger in the first
mode and, in a second mode, shut the first fan (40) off to increase
a temperature of the refrigerant passing through the second heat
exchanger to defrost the build-up.
3. The system (70) of claim 1 wherein the means comprises: a valve
(78) along a bypass flowpath from a first location along the
flowpath between the compressor and the first heat exchanger to a
second location between an expansion device and the second heat
exchanger, the valve openable to switch the system into a bypass
mode where at least a portion of a compressor outlet flow passes
along the bypass flowpath and to the second heat exchanger and is
in sufficient quantity to heat the second heat exchanger to defrost
the ice buildup.
4. The system (100) of claim 1 wherein the means comprises: a
reversing valve (102) actuatable to put the system in a second mode
wherein flow through the first (24) and second (28) heat exchangers
is reversed.
5. The system of claim 1 wherein the means further is means for
heating the cooler interior volume to prevent freezing of the
contents when an outside temperature falls below a threshold.
6. The system of claim 1 being a self-contained externally
electrically powered beverage cooler positioned outdoors.
7. The system of claim 1 wherein: the first (24) and second (28)
heat exchangers and compressor (22) are removable from a housing of
the system as a unit without need to previously empty contents of
the system.
8. The system of claim 1 wherein: the refrigerant comprises, in
major mass part, CO.sub.2; and the first (24) and second (28) heat
exchangers are refrigerant-air heat exchangers.
9. The system of claim 1 wherein: the refrigerant consists
essentially of CO.sub.2; and the first (24) and second (28) heat
exchangers are refrigerant-air heat exchangers each having an
associated fan (40, 42), a first mode air flow (44) across the
first heat exchanger (24) being an external flow and a first mode
airflow (46) across the second heat exchanger (28) being a
recirculating internal airflow.
10. The system of claim 1 in combination with said contents which
include: a plurality of beverage containers in a 0.3-4.0 liter size
range.
11. The system of claim 10 being selected from the group consisting
of: a cash-operated vending machine; a transparent door front,
closed back, display case; and a top access cooler chest.
12. A method for operating a cooler system (20; 70; 100)
comprising: in at least a first mode of system operation, operating
a compressor (22) to compress and drive a refrigerant along a
flowpath (32; 72; 100, 112); in the first mode, rejecting heat from
the refrigerant in a first heat exchanger (24) along the flowpath
(32; 72; 100, 112) downstream of the compressor (22); in the first
mode, absorbing heat to the refrigerant in a second heat exchanger
(28) along the flowpath (32; 72; 100, 112) upstream of the
compressor (22) to cool contents of an interior volume of the
system; and in a second mode of operation, means defrosting an ice
buildup on the second heat exchanger using refrigerant in the
second heat exchanger.
13. The method of claim 12 wherein a transition between the first
mode and the second mode is performed by: a controller (50)
programmed or configured to run a first fan (40) to drive a first
air flow (44) across the first heat exchanger in the first mode
and, in the second mode, shut the first fan (40) off to increase a
temperature of the refrigerant passing through the second heat
exchanger to defrost the build-up.
14. The method of claim 12 wherein a transition between the first
mode and the second mode is performed by: a valve (78) along a
bypass flowpath from a first location along the flowpath between
the compressor and the first heat exchanger to a second location
between an expansion device and the second heat exchanger, and
wherein the valve is opened to switch the system into said second
mode where at least a portion of a compressor outlet flow passes
along the bypass flowpath and to the second heat exchanger and is
in sufficient quantity to heat the second heat exchanger to defrost
the ice buildup.
15. The method of claim 12 wherein a transition between the first
mode and the second mode is performed by: a reversing valve (102)
actuated to put the system into the second mode wherein flow
through the first (24) and second (28) heat exchangers is reversed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Benefit is claimed of U.S. Patent Application Ser. No.
60/663,961, filed Mar. 18, 2005, and entitled "BOTTLE COOLER
DEFROSTER AND METHODS", the disclosure of which is incorporated by
reference herein as if set forth at length. Copending application
docket 05-258-WO, entitled HIGH SIDE PRESSURE REGULATION FOR
TRANSCRITICAL VAPOR COMPRESSION SYSTEM and filed on even date
herewith, discloses prior art and inventive cooler systems. The
disclosure of said application is incorporated by reference herein
as if set forth at length. The present application discloses
possible modifications to such systems.
BACKGROUND OF THE INVENTION
[0002] The invention relates to refrigeration. More particularly,
the invention relates to beverage coolers.
[0003] The CO.sub.2 bottle cooler utilizes a compressor, a gas
cooler, an expansion device, and an evaporator to transfer heat
energy from a low temperature energy reservoir to a high
temperature energy sink. This transfer is achieved with the aid of
electrical energy input at the compressor. A temperature difference
between the outdoor air and the refrigerant drives the thermal
energy transfer from the interior air to the refrigerant as it
passes through the lower temperature heat exchanger (e.g.,
evaporator). The fan continues to move fresh air across the
evaporator surface, maintaining the temperature difference, and
evaporating the refrigerant. If the surface temperature of the
evaporator is below the dew-point temperature of the moist air
stream, water will condense onto the fins. When the surface of the
evaporator is below freezing, water droplets that condense on the
surface can freeze. Frost crystals then grow from the frozen
droplets and begin to block the airflow passage through the
evaporator fins. The blockage increases the pressure drop through
the evaporator, which reduces the airflow. As a result of the
insulating effect of frost and blockage of airflow, the refrigerant
temperature in the evaporator decreases, which ultimately causes
degradation in the bottle cooler performance and reduction of the
cooling capacity and COP. Eventually, a defrost cycle must be
initiated.
[0004] The existing method is to shut off the compressor and higher
temperature (at least in a normal mode) heat exchanger (e.g.,
condenser) fan while still keep the evaporator fan running. By
circulating the air inside the bottle cooler cabinet through the
evaporator, the frost on the coil can be heated. Since the
temperature of the air in the cabinet (nominally 3.3.degree. C.
(38.degree. F.), more broadly 2-4.degree. C. (36-39.degree. F.)) is
very close to the temperature of the frost (0.degree. C.
(32.degree. F.)), the defrost process usually takes a long
time.
[0005] If the bottle cooler is installed outdoors, an electric
heater is usually needed to heat the air inside the cabinet to keep
the beverage from freezing. Because the efficiency of the electric
heater is at most 100%, the costs of heating the air in winter is
quite significant.
SUMMARY OF THE INVENTION
[0006] A bottle cooler system includes means for switching the
system to a second mode of operation wherein refrigerant in the
evaporator defrosts an ice buildup on the evaporator. The details
of one or more embodiments of the invention are set forth in the
accompanying drawings and the description below. Other features,
objects, and advantages of the invention will be apparent from the
description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic of a first CO.sub.2 bottle cooler.
[0008] FIG. 2 is a schematic of a first alternate CO.sub.2 bottle
cooler.
[0009] FIG. 3 is a pressure-enthalpy diagram of the defrost cycle
of the CO.sub.2 bottle cooler of FIG. 2 in a defrost mode.
[0010] FIG. 4 is a schematic of a second alternate CO.sub.2 bottle
cooler in a cooling mode.
[0011] FIG. 5 is a schematic of the CO.sub.2 bottle cooler of FIG.
4 in a defrost mode.
[0012] FIG. 6 is a side schematic view of a display case bottle
cooler including a refrigeration and air management cassette.
[0013] FIG. 7 is a view of a refrigeration and air management
cassette.
[0014] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0015] FIG. 1 schematically shows a transcritical vapor compression
system 20 of a bottle cooler. The system comprises a compressor 22,
a first heat exchanger 24, an expansion device 26, and a second
heat exchanger 28. An accumulator 30 may also be located in a
suction line portion of the refrigerant flowpath 32 between the
outlet of the second heat exchanger 28 and the inlet 34 of the
compressor 22. A discharge line of the flowpath 32 extends from the
outlet 36 of the compressor to the inlet of the first heat
exchanger 24. Additional lines connect the first heat exchanger
outlet to the expansion device inlet and the expansion device
outlet to the second heat exchanger inlet. An exemplary expansion
device 26 is an electronic expansion device. Alternative devices
are disclosed in the Docket 05-258-WO application identified
above.
[0016] The heat exchangers 24 and 28 may each take the form of a
refrigerant-to-air heat exchanger. Air flows across one or both of
these heat exchangers may be forced. For example, one or more fans
40 and 42 may drive respective air flows 44 and 46 across the coils
of the two heat exchangers. The system may include a controller 50
which may be coupled to one or both of the expansion device 26 and
compressor 22 to control their respective operations. The
controller 50 may be configured to accept user input and/or may be
configured to accept input from one or more sensors (e.g.,
temperature or pressure sensors). FIG. 1 shows an exemplary pair of
temperature sensors 52 and 54 (e.g., thermocouples). The first
temperature sensor 52 is positioned to measure a temperature of the
coil of the second heat exchanger 28 (advantageously positioned to
measure the air temperature entering or exiting the heat exchanger
or to measure the saturation temperature refrigerant in the heat
exchanger). The second temperature sensor 54 is positioned to
measure a temperature of refrigerant in the suction line.
[0017] The first heat exchanger 24 may be positioned external to
the refrigerated volume of the bottle cooler. The second heat
exchanger 28 may be positioned internal to such volume or along a
recirculating air flowpath to/from that volume.
[0018] In a first mode of operation (e.g., a normal cooling mode)
the compressor is on and the fans 40 and 42 drive their respective
air flows 44 and 46. The first heat exchanger 24 acts as a gas
cooler discharging heat to the air flow 44 to cool the refrigerant
passing through the first heat exchanger. This refrigerant is
expanded passing through the expansion device 26 so that its
temperature further drops. The second heat exchanger 28 acts as an
evaporator, cooling the air flow 46 and thus the refrigerated
volume of the bottle cooler. During normal operation, frost may
accumulate on the coils of the second heat exchanger 28.
[0019] In a second (defrost) mode of operation the first fan 40 is
shut-off, decreasing the heat extraction from the refrigerant in
the first heat exchanger 24. As a result, the refrigerant entering
the second heat exchanger 28 may be above 0.degree. C. Thus, this
refrigerant may be effective to defrost the second heat exchanger.
Additionally, the fan 42 may continue to operate. To the extent
that the air within the beverage cooler is above 0.degree. C., the
air flow 46 will further facilitate defrosting of the second heat
exchanger 28. While in defrost mode, if the expansion device 26 is
controllable, the expansion device may be opened to provide a
larger opening size to prevent over pressurization within the high
pressure portion of the system.
[0020] The need to defrost may be determined in a variety of ways.
In one example, a timer is used (e.g., included in the controller)
and the system switches to the defrost mode after a predetermined
period of time has elapsed. If a more complicated controller is
used, a temperature sensor or combination of temperature sensors
can be used. For example, when both (1) a first temperature
measured by the temperature sensor 52 is below a first
predetermined value (thus indicating a potential for frosting by
distinguishing a potential frosting condition from a pulldown
condition; e.g., 40.degree. F. for air temperature or 33.degree. F.
for a coil temperature); and (2) the difference between a second
temperature measured by the temperature sensor 54 and the first
temperature is above a second value, the evaporator may be assumed
to be frosted and a defrost mode can be entered.
[0021] The system may shift back to the cooling mode from the
defrost mode in similar fashion. A fixed time is one example. A
sensed condition (e.g., when the output of one of the temperature
sensor 52 and the temperature sensor 54 exceeds a third
predetermined value; e.g., 40.degree. F. for air temperature or
35.degree. F. for coil temperature).
[0022] FIG. 2 shows an alternate system 70 having a refrigerant
flowpath 72 with first and second segments/branches 74 and 76
between the compressor outlet 36 and the inlet of the second heat
exchanger 28. The first branch 74 may contain the first heat
exchanger 24 and the expansion device 26 in a similar fashion to
the first system 20. The second branch 76 contains a switching
valve 78. The switching valve 78 may also be controlled by the
controller 50 (not shown for this and the remaining
embodiments).
[0023] In a first (cooling) mode of operation, the switching valve
78 is closed and operation is similar to the first mode of the
system 20. In the second (defrost) mode, the switching valve 78 is
open, causing at least a portion of the compressed refrigerant to
bypass the first branch 74 and, thereby, lack the cooling otherwise
provided by the first heat exchanger 24 (even with its fan 40 off)
and expansion device 26. There may still be some flow through the
first branch 74. However, the first heat exchanger 24 and the
expansion device 26 may be relatively restrictive so that a
majority of the system flow passes along the second branch 76.
[0024] Because of the refrigerant bypass along the second branch
76, the net resulting temperature of refrigerant entering the
second heat exchanger 28 in the system 70 defrost mode may be
higher than for the defrost mode of the system 20.
[0025] The heating capacity of the system during the defrost mode
will essentially be the same as the input power to the compressor.
The input power to the compressor is a function, of the discharge
pressure of the compressor. To maximize the heating capacity, the
input power should be maximized and thus the discharge pressure
should be as high as possible without producing overpressurization.
In this way, the power input, and thus the heating capacity is
maximized, which minimizes the defrost time. Minimizing the defrost
time allows the system to exit the defrost mode and return to the
cooling mode quickly, which minimizes disturbances to the
temperature of the product stored in the cooler.
[0026] FIG. 3 is a pressure-enthalpy diagram of the defrost cycle
of the system 70. The refrigerant flowpath includes a first leg 90
through the compressor. During this leg 90, both the pressure and
enthalpy increase to a point 91 due to the input of mechanical
energy. A second leg 92 is associated with the second branch 76 and
refrigerant passage through the switching valve 78. The switching
valve 78 acts as an expansion device so that the second leg 92 is
preferably close to isenthalpic ending at a reduced pressure point
93. From the reduced pressure point 93, a third leg 94 represents
essentially constant pressure passage through the second heat
exchanger 28, giving up heat to melt the frost accumulation. The
exemplary third leg 94 returns to a reduced enthalpy origin 95 from
which the first leg 90 resumes. In the exemplary illustration, the
origin 95 (minimum enthalpy and pressure point) is at or near the
saturated vapor line 96 separating the mixed liquid-vapor region 97
("vapor dome") from the vapor region 98. In alternative situations,
the cycle may occur entirely within the vapor region 98 remote of
the vapor dome. In yet other possible situations, a portion of the
cycle may be along or within the vapor dome.
[0027] Another alternative is to add a flow reversing valve (e.g.,
a four-way valve). This may be particularly useful for bottle
coolers that will be installed outdoors. During the summer when
cooling is needed, the CO.sub.2 bottle cooler operates as a cooling
device, lowering the temperature of the air inside the cabinet. In
winter, by activating the four-way valve, the flow is reversed and
the bottle cooler operates as a heat pump, providing heat to the
air inside the cabinet. Because the efficiency (or COP) of a heat
pump is always much higher than 100%, the operation cost for
heating the air is significantly reduced. This heat pump operation
mode can also be used to defrost the evaporator coil.
[0028] FIG. 4 shows a system 100 having a flow reversing valve 102
having a flow reversing valve element 104 with two distinct
flowpaths. An exemplary element is a rotary element. FIG. 4 shows
the valve element 104 oriented in a first (cooling) mode.
[0029] FIG. 5 shows the valve element 104 oriented to provide a
second (defrost or heat pump) mode. The valve 102 links a
compressor loop 110 of the refrigerant flowpath to a main loop 112.
The heat exchangers 24 and 28 and expansion device 26 are
positioned along the main loop 112. In both modes, flow along the
compressor loop 110 is in the same direction. The valve serves to
reverse flow along the main loop 112. In the defrost mode, the
second heat exchanger 28 acts as a gas cooler. The hot refrigerant
gas passing through the second heat exchanger 28 may be
particularly effective to melt frost. The first heat exchanger 24
may act as an evaporator. In the defrost mode, the expansion device
26 regulates pressure in the second heat exchanger 28.
[0030] A particular area for implementation of the invention is in
bottle coolers, including those which may be positioned outdoors or
must have the capability to be outdoors (presenting large
variations in ambient temperature). FIG. 6 shows an exemplary
cooler 200 having a removable cassette 202 containing the
refrigerant and air handling systems. The exemplary cassette 202 is
mounted in a compartment of a base 204 of a housing. The housing
has an interior volume 206 between left and right side walls, a
rear wall/duct 216, a top wall/duct 218, a front door 220, and the
base compartment. The interior contains a vertical array of shelves
222 holding beverage containers 224.
[0031] The exemplary cassette 202 draws the air flow 44 through a
front grille in the base 224 and discharges the air flow 44 from a
rear of the base. The cassette may be extractable through the base
front by removing or opening the grille. The exemplary cassette
drives the air flow 46 on a recirculating flow path through the
interior 206 via the rear duct 210 and top duct 218.
[0032] FIG. 7 shows further details of an exemplary cassette 202.
The heat exchanger 28 is positioned in a well 240 defined by an
insulated wall 242. The heat exchanger 28 is shown positioned
mostly in an upper rear quadrant of the cassette and oriented to
pass the air flow 46 generally rearwardly, with an upturn after
exiting the heat exchanger so as to discharge from a rear portion
to the cassette upper end, a drain 250 may extend through a bottom
of the wall 242 to pass water condensed from the flow 46 to a drain
pan 252. A water accumulation 254 is shown in the pan 252. The pan
252 is along an air duct 256 passing the flow 44 downstream of the
heat exchanger 24. Exposure of the accumulation 254 to the heated
air in the flow 44 may encourage evaporation.
[0033] One or more embodiments of the present invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. For example, when implemented as a
remanufacturing of an existing system or reengineering of an
existing system configuration, details of the existing
configuration may influence details of the implementation.
Accordingly, other embodiments are within the scope of the
following claims.
* * * * *