U.S. patent application number 11/908408 was filed with the patent office on 2008-08-07 for heat exchanger arrangement.
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 | 20080184713 11/908408 |
Document ID | / |
Family ID | 37024266 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080184713 |
Kind Code |
A1 |
Huff; Hans-Joachim ; et
al. |
August 7, 2008 |
Heat Exchanger Arrangement
Abstract
A refrigeration system includes a compressor for driving a
refrigerant along a flow path in at least a first mode of system
operation; a first heat exchanger along the flow path downstream of
the compressor in the first mode; a second heat exchanger along the
flow path upstream of the compressor in the first mode; and a
pressure regulator or expansion device in the flow path downstream
of the first heat exchanger and upstream of the second heat
exchanger in the first mode, wherein the first heat exchanger is
positioned within a housing which defines a flow path for heat
exchange fluid and the housing defines a zone of reduced flow area
along the flow path, and wherein the first heat exchanger is
positioned in the zone of reduced flow area.
Inventors: |
Huff; Hans-Joachim; (West
Hartford, CT) ; Sienel; Tobias H.; (East Hampton,
MA) ; Chen; Yu; (East Hartford, CT) ; Verma;
Parmesh; (Manchester, 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: |
37024266 |
Appl. No.: |
11/908408 |
Filed: |
December 30, 2005 |
PCT Filed: |
December 30, 2005 |
PCT NO: |
PCT/US2005/047523 |
371 Date: |
September 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60663962 |
Mar 18, 2005 |
|
|
|
Current U.S.
Class: |
62/56 ;
62/527 |
Current CPC
Class: |
F25D 2323/00271
20130101; F28F 1/32 20130101; F25B 6/04 20130101; F25D 19/02
20130101; F25D 2500/02 20130101; F28F 9/262 20130101; F25D
2323/00264 20130101; F28F 1/122 20130101; F25D 23/003 20130101;
F28D 1/0477 20130101; F25B 2309/061 20130101; F25D 2317/0661
20130101; F25D 2317/0651 20130101; F25B 9/008 20130101 |
Class at
Publication: |
62/56 ;
62/527 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F25B 41/06 20060101 F25B041/06 |
Claims
1. A refrigeration system comprising: a compressor for driving a
refrigerant along a flow path in at least a first mode of system
operation; a first heat exchanger along the flow path downstream of
the compressor in the first mode; a second heat exchanger along the
flow path upstream of the compressor in the first mode; and a
pressure regulator or expansion device in the flow path downstream
of the first heat exchanger and upstream of the second heat
exchanger in the first mode, wherein the first heat exchanger is
positioned within a housing which defines a flow path for heat
exchange fluid and the housing defines a zone of reduced flow area
along the flow path, and wherein the first heat exchanger is
positioned in the zone of reduced flow area.
2. The system of claim 1, wherein the first heat exchanger
comprises a wire-on-tube heat exchanger.
3. The system of claim 1, wherein the heat exchanger comprises a
plurality of substantially parallel refrigerant flow path segments,
and wherein the heat exchange fluid is directed in counter flow
with respect to refrigerant in the first heat exchanger, and
substantially transverse to the refrigerant flow path segments.
4. A refrigeration system comprising: a compressor for driving a
refrigerant along a flow path in at least a first mode of system
operation; a first heat exchanger along the flow path downstream of
the compressor in the first mode; a second heat exchanger along the
flow path upstream of the compressor in the first mode; and a
pressure regulator or expansion device in the flow path downstream
of the first heat exchanger and upstream of the second heat
exchanger in the first mode, wherein the first heat exchanger
comprises a plurality of substantially parallel refrigerant flow
path segments, and wherein heat exchange fluid for the first heat
exchanger is directed in counter flow substantially transverse to
the refrigerant flow path segments.
5. The system of claim 4 wherein the refrigerant flow paths have an
upstream end and a downstream end with respect to refrigerant flow
from the compressor, and wherein the heat exchange fluid is
directed from the downstream end to the upstream end of the
refrigerant flow path segments to provide the counter flow.
6. The system of claim 4, further comprising structure for guiding
flow of the heat exchange fluid substantially transverse to the
refrigerant flow path segments.
7. The system of claim 4 wherein the refrigerant flow path segments
are defined by at least one refrigerant flow path in a serpentine
arrangement.
8. The system of claim 4 wherein the refrigerant flow path segments
are defined by a plurality of heat exchange modules arranged in
series with respect to refrigerant flow and in counter flow with
the heat exchange fluid.
9. The system of claim 8 wherein each heat exchange module
comprises a plurality of substantially parallel refrigerant flow
path segments.
10. The system of claim 4 wherein: the refrigerant comprises, in
major mass part, CO.sub.2; and the first and second heat exchangers
are refrigerant-air heat exchangers.
11. The system of claim 4, wherein the system is adapted to operate
in a transcritical vapor compression mode.
12. A beverage cooling device comprising the system of claim 4.
13. The device of claim 12, wherein the beverage cooling device
comprises a housing having an inlet and an outlet for the heat
exchange fluid, wherein the housing defines a flow restriction
between the inlet and the outlet, and wherein the first heat
exchanger is positioned at the flow restriction.
14. A method for exchanging heat between a refrigerant and a heat
exchange fluid, comprising: operating a compressor to drive a
refrigerant from the compressor to a heat exchanger in a housing
which defines a flow path for heat exchange medium, wherein the
housing defines a zone of decreased flow area for the heat exchange
medium, and wherein the heat exchanger is positioned in the zone;
and passing a heat exchange fluid over the heat exchanger in the
zone in a direction which is substantially transverse to the
substantially parallel flow paths.
15. The method of claim 14, wherein the heat exchanger comprises a
plurality of substantially parallel flow path segments.
16. The method of claim 15, further comprising feeding the
substantially parallel flow path segments sequentially so as to
define at least one upstream flow path and at least one downstream
flow path with respect to refrigerant flow from the compressor, and
wherein the passing step comprises passing heat exchange fluid over
the substantially parallel flow path segments from the downstream
flow path to the upstream flow path.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This applications claims the benefit of the filing date of
earlier filed provisional application Ser. No. 60/663,962 filed
Mar. 18, 2005. Further, copending application docket 05-258-WO,
entitled HIGH SIDE PRESSURE REGULATION FOR TRANSCRITICAL VAPOR
COMPRESSION SYSTEM and filed on even date herewith, and the
aforesaid provisional application Ser. No. 60/663,962, disclose
prior art and inventive cooler systems. The disclosure of said
applications is incorporated by reference herein as if set forth at
length.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a heat exchanger arrangement for a
vapor compression system, especially a transcritical vapor
compression system.
[0003] The heat rejection process in transcritical vapor
compression refrigeration applications and systems occurs at a
pressure above the critical pressure of the refrigerant. The
refrigerant does not undergo a phase change during this process and
the temperature of the refrigerant changes throughout the entire
heat rejection process. The energy efficiency of the refrigeration
system increases if the heat exchanger arrangement approaches an
ideal counter flow arrangement with the heat sink.
[0004] It is therefore a primary object of the invention to provide
a system having an efficient heat exchanger arrangement.
[0005] It is a further object of the invention to provide such a
system which is readily incorporated into existing refrigeration
systems.
[0006] Other objects and advantages will appear herein.
SUMMARY OF THE INVENTION
[0007] According to the invention, the foregoing objects and
advantages have been attained.
[0008] According to the invention, a refrigeration system is
provided which comprises a compressor for driving a refrigerant
along a flow path in at least a first mode of system operation; a
first heat exchanger along the flow path downstream of the
compressor in the first mode; a second heat exchanger along the
flow path upstream of the compressor in the first mode; and a
pressure regulator or expansion device in the flow path downstream
of the first heat exchanger and upstream of the second heat
exchanger in the first mode, wherein the first heat exchanger is
positioned within a housing which defines a flow path for heat
exchange fluid and the housing defines a zone of reduced flow area
along the flow path, and wherein the first heat exchanger is
positioned in the zone of reduced flow area.
[0009] According to the invention, a refrigeration system is
provided which includes a compressor for driving a refrigerant
along a flow path in at least a first mode of system operation; a
first heat exchanger along the flow path downstream of the
compressor in the first mode; a second heat exchanger along the
flow path upstream of the compressor in the first mode; and a
pressure regulator or expansion device in the flow path downstream
of the first heat exchanger and upstream of the second heat
exchanger in the first mode, wherein the first heat exchanger
comprises a plurality of substantially parallel refrigerant flow
paths, and wherein heat exchange fluid for the first heat exchanger
is directed in counter flow substantially transverse to the
refrigerant flow paths.
[0010] A preferred embodiment is drawn to transcritical vapor
compression operation using CO.sub.2 refrigerant fluid. Serpentine
and/or parallel modular refrigerant flow paths are provided. A
particular environment of use for the invention is in connection
with so-called bottle coolers, or cooling units for cooling and
storing beverages. Such coolers can be in the form of vending
machines are refrigerator cases, for example.
[0011] In one embodiment, the housing of the beverage cooler
defines an internal flow area for heat exchange fluid such as air,
and this flow area has a flow restriction which serves to speed
flow of the heat exchange fluid therethrough. According to the
invention, the refrigerant flow paths are positioned at the flow
restriction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic illustration of a counter flow heat
exchanger arrangement according to the invention;
[0013] FIG. 2 is a schematic illustration of an alternate counter
flow heat exchanger arrangement according to the invention;
[0014] FIG. 3 is an illustration of a preferred structure for a
beverage cooler including the heat exchanger arrangement of the
present invention;
[0015] FIG. 4 illustrates a preferred type of heat exchanger
according to the invention; and
[0016] FIG. 5 illustrates a preferred embodiment of the structure
shown in FIG. 3.
DETAILED DESCRIPTION
[0017] The invention relates to refrigeration systems and, more
particularly, to systems operating in a transcritical vapor
compression regime, one particular embodiment of which is a
beverage cooler. According to this invention, a heat exchanger
configuration is utilized which provides efficient exchange of heat
between a refrigerant fluid and a heat exchange fluid.
[0018] A transcritical vapor compression system operates at
pressures above the critical pressure of the refrigerant and,
therefore, the refrigerant does not undergo a phase change during
the process. Under these circumstances, it has been found that a
counter flow arrangement of the heat rejection heat exchanger with
respect to the heat exchange fluid provides better efficiency in
operation, and this counter flow arrangement can be approached by a
heat exchanger consisting of a single flow path of several parallel
flow path segments.
[0019] It has also been found that the position of a heat exchanger
within the housing is important, and positioning of a heat
exchanger in an area of increased flow velocity has been found to
make the heat exchange process more efficient.
[0020] FIG. 1 shows a refrigerant system 10 having a compressor 12,
a first heat exchanger 14, a second heat exchanger 16, an expansion
device 18 and refrigerant lines connecting these components in
serial fashion as illustrated.
[0021] FIG. 3 further illustrates a beverage cooler 20 into which
system 10 is positioned. FIG. 3 shows compressor 12 as well as
first heat exchanger 14 and second heat exchanger 16. Cooler 20 has
a housing which defines a first heat exchange fluid flow path
(arrows 22) wherein external air is drawn from an inlet 24, past
first heat exchanger 14, and to an outlet 26. A second fluid flow
path (arrows 28) is also defined, and passes from within the space
of the beverage cooler, past second heat exchanger 16, and back to
the refrigerated space. As shown in FIG. 3, flow path 22 passes
through the housing and passes through a zone 23 of reduced flow
area. At zone 23, air flowing through the housing increases in
velocity. According to the invention, it is preferred to position
heat exchanger 14 at zone 23.
[0022] FIG. 1 shows a simplified configuration of first heat
exchanger 14 in accordance with the invention, and shows the heat
exchanger in the form of a single refrigerant flow path or tube
formed into a series of substantially parallel flow path segments.
In this embodiment, the segments are serially fed with refrigerant
fluid from compressor 12 such that the flow path segments include
an upstream flow path segment 30 and a downstream flow path segment
32. In the embodiment shown in FIG. 1, all flow path segments are
part of a single serpentine path and, thus, each segment is
progressively further downstream as it relates to flow of
refrigerant, when considered from upstream segment 30 to downstream
segment 32. First heat exchanger 14 is positioned within the
housing of beverage cooler 20 such that incoming heat exchange
fluid 22 first passes the downstream refrigerant flow path segment
32, and then passed increasingly over the next flow path segments
in order until finally passing upstream flow path 30. This
configuration has been found, according to the invention, to
provide for good heat exchange between the heat exchange fluid and
the refrigerant. particularly when the system defined is a
transcritical vapor compression system.
[0023] FIG. 2 shows an alternative embodiment wherein the flow path
segments are broken up into two main groups or components of the
heat exchanger, and wherein the groups are positioned so as to
define an upstream and a downstream component. Within each
component, segments are defined in parallel. Incoming heat exchange
fluid, as shown, passes first over the downstream component and
then over the upstream component.
[0024] It should be appreciated that the configurations of FIGS. 1
and 2 are examples of the counter flow arrangement of the present
invention, and that alterations to these specific structures could
of course be made by a person of skill in the art, well within the
broad scope of the present invention. Further, one preferred
embodiment of a heat exchanger for use in accordance with the
invention is a wire-on-tube heat exchanger, an example of which is
illustrated in FIG. 4. FIG. 4 shows a portion of a heat exchanger
50 defined by a single flow tube 52 which has a serpentine flow
configuration as illustrated in FIG. 1 and which also is configured
to have a vertical structure as well. Specifically, heat exchanger
50 is shaped to have alternating angled sections 54, 56 when
considered in the direction of air flow as shown by arrow 58. A
series of wires 60 are positioned along heat exchanger 50 in a
substantially transverse direction to the paths defined by tube 52,
and wires 60 preferably follow tube 52 along the sections 54, 56.
Wires 60 can advantageously be positioned on both sides of tube 52
as shown in FIG. 4. FIG. 4 illustrates several turns of a
wire-on-tube heat exchanger. It should be appreciated that the
actual heat exchanger could continue for one or more additional
angled sections 54, 56, to provide for the desired flow length of
the heat exchanger.
[0025] As set forth above, FIG. 3 shows a further embodiment of the
present invention wherein system 10 is incorporated into a beverage
cooler 20. In this system, the beverages would be stored in a
refrigerated area positioned above the portion illustrated, and
communicated with the flow of air along path 28.
[0026] Flow path 22 represents flow of outside or ambient air which
enters through an inlet 24 located at the front 34 of cooler 20 and
passes a first component 14a of first heat exchanger 14 and then a
second component 14b of first heat exchanger 14, and then to an
outlet 26 preferably at the rear 36 of cooler 20.
[0027] An inner housing wall 38 separates the area of flow path 22
from the area of flow path 28. This wall also serves to define a
zone along flow path 22 where the cross sectional area, or flow
area, is constricted. This reduction in flow area along path 22
serves to increase the velocity of flow through same. For this
reason, second component 14b of first heat exchanger 14 is
preferably positioned at the zone of restricted flow as shown so
that the increased flow velocity of heat exchange fluid passes over
this heat exchanger. It has been found, according to the invention,
that this positioning helps to further increase the efficiency in
heat exchange between the heat exchange fluid and the refrigerant.
Reduced flow area zone 23 is in this embodiment shown toward the
rear of path 22, and is substantially completely filled with heat
exchanger component 14b.
[0028] In further accordance with the invention, and as shown in
FIG. 5, a heat exchanger such as the wire-on-tube heat exchanger of
FIG. 4 can advantageously be positioned at the zone 23 of increased
flow velocity, and this heat exchanger is particularly efficient in
exchanging heat with the flow of air passing through zone 23. In
this configuration, it is possible to completely eliminate the heat
exchanger from the location occupied by heat exchanger 14a in FIG.
3, and thereby provide this space for other uses. Thus, in one
aspect of the present invention, a heat exchanger is advantageously
positioned within the housing at a zone 23 where there is a
decreased air flow area and a resulting increase in air flow
velocity, and it is further preferred to position a wire on tube
heat exchanger in zone 23. As used herein, a wire-on-tube heat
exchanger is considered to be a heat exchanger defined by one or
more tubes, preferably a single tube, which has wires positioned
for interaction with a passing air flow to increase heat exchange
efficiency. Such a heat exchanger is particularly desirable for
positioning in a zone such as zone 23 since most heat exchangers
would have too great of a resistance to air flow to position in
such a location. However, a wire-on-tube heat exchanger has
sufficiently low resistance to air flow that positioning of such a
heat exchanger in zone 23 does not significantly interfere with the
flow dynamics of the system, and further the wire-on-tube heat
exchanger is particularly efficient at heat exchange under such
flow conditions.
[0029] As set forth above, FIG. 3 shows one embodiment of structure
used to generate flow along paths 22 and path 28. Flow along flow
path 22 can be generated using a fan 40 driven by a motor 42 as
shown. In similar fashion, flow along path 28 can be generated by a
fan 44 driven by a motor 46 as shown. Other structures for
generating the desired flows would be well known to a person of
skill in the art and are well within the scope of the present
invention.
[0030] It should be appreciated that the refrigerant flow paths
represented by first heat exchanger 14 and its components 14a, 14b,
can be formed as tubes, micro-channels or mini-channels, or the
like. The secondary fluid surface area of the tube can be
increased, for example with fins attached to the tube. The fins can
be of any type, and can be in the shape of plates, wires, louvered
fins or any other shape. One preferred embodiment is that referred
to as a "wire-on-tube" configuration as described above and
illustrated in FIG. 4.
[0031] In bottle cooler applications and other small refrigeration
applications with carbon dioxide (CO.sub.2) as refrigerant this
invention offers particular benefits. This invention allows
utilizing the space in a volume available for the heat exchanger
most effectively. Additionally, the high operating pressure of
CO.sub.2 refrigeration applications reduces the effect of pressure
drop on the system performance. Therefore, the high pressure drop
in a single-tube serpentine arrangement of the heat exchanger as
shown in FIG. 1 does not reduce the system performance
significantly, while the effective utilization of the volume
available for the heat exchanger paths maximizes the system
performance. Specifically, the volume normally occupied by a heat
exchanger 14a (FIG. 3) can be utilized for other system components,
or to make existing components larger and/or more efficient.
[0032] The system according to the invention is discussed herein in
terms of having upstream and downstream relationship with various
components of the refrigerant circuit in at least one mode of
operation. This takes into account that a device such as a beverage
cooler utilizing the apparatus of the present invention could have
more than one mode of operation, and/or intermittent modes of
operation, aside from the "normal" cooling mode wherein the first
heat exchanger gives off heat and the second heat exchanger cools
air within a refrigerated space.
[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.
* * * * *