U.S. patent application number 11/793880 was filed with the patent office on 2008-04-24 for heat exchanger with fluid expansion in header.
This patent application is currently assigned to Carrier Corporation. Invention is credited to Robert A. Chopko, Mikhail B. Gorbounov, Allen C. Kirkwood, Steven A. Lozyniak, Michael F. Taras, Parmesh Verma.
Application Number | 20080092587 11/793880 |
Document ID | / |
Family ID | 36777708 |
Filed Date | 2008-04-24 |
United States Patent
Application |
20080092587 |
Kind Code |
A1 |
Gorbounov; Mikhail B. ; et
al. |
April 24, 2008 |
Heat Exchanger with Fluid Expansion in Header
Abstract
A heat exchanger includes a plurality of flat, multi-channel
heat exchange tubes extending between spaced headers. Each heat
exchange tube has a plurality of flow channels extending
longitudinally in parallel relationship from its inlet end to its
outlet end. A plurality of connectors are positioned between the
inlet header and the heat transfer tubes such that the connector
inlet ends are in fluid flow communication with the header through
a relatively small cross-sectional flow area openings and the
connector outlet ends are adapted to receive the inlet end of a
heat exchanger tube. The connector defines a fluid flow pathway
from the relatively small cross-sectional flow area opening in the
inlet end of the connector to an outlet opening in the outlet end
of the connector that opens to the flow channels of the heat
exchange tube received in the outlet end of the connector.
Inventors: |
Gorbounov; Mikhail B.;
(South Windsor, CT) ; Lozyniak; Steven A.; (South
Windsor, CT) ; Verma; Parmesh; (Manchester, CT)
; Taras; Michael F.; (Fayetteville, NY) ; Chopko;
Robert A.; (Baldwinsville, NY) ; Kirkwood; Allen
C.; (Brownsburg, IN) |
Correspondence
Address: |
MARJAMA MULDOON BLASIAK & SULLIVAN LLP
250 SOUTH CLINTON STREET
SUITE 300
SYRACUSE
NY
13202
US
|
Assignee: |
Carrier Corporation
Farmington
CT
06034-4015
|
Family ID: |
36777708 |
Appl. No.: |
11/793880 |
Filed: |
December 28, 2005 |
PCT Filed: |
December 28, 2005 |
PCT NO: |
PCT/US05/47363 |
371 Date: |
June 21, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60649269 |
Feb 2, 2005 |
|
|
|
Current U.S.
Class: |
62/498 ;
165/104.21 |
Current CPC
Class: |
F28F 9/0224 20130101;
F28F 9/0282 20130101; F25B 41/385 20210101; F28F 9/185 20130101;
F28F 9/028 20130101; F25B 41/30 20210101; F25B 39/028 20130101 |
Class at
Publication: |
062/498 ;
165/104.21 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F28F 9/02 20060101 F28F009/02 |
Claims
1. A heat exchanger comprising: a header defining a chamber for
collecting a fluid; and at least one heat exchange tube defining a
plurality of discrete fluid flow paths therethrough and having an
inlet opening to said plurality of fluid flow paths; and a
connector having an inlet end and an outlet end and defining a
fluid flow path extending from said inlet end to said outlet end,
said inlet end in fluid flow communication with the chamber of said
header through a first opening and said outlet end in fluid
communication with the inlet opening of said at least one heat
exchange tube through a second opening, said first opening having a
relatively small cross-sectional flow area.
2. A heat exchanger as recited in claim 1 wherein said first
opening of said connector comprises an expansion orifice.
3. A heat exchanger as recited in claim 1 wherein the fluid flow
path of said connector comprises a divergent fluid flow path
expanding in cross-section in the direction of fluid flow
therethrough from said first opening to said second opening.
4. A heat exchanger as recited in claim 3 wherein said first
opening of said connector comprises an expansion orifice.
5. A heat exchanger as recited in claim 1 wherein said at least one
heat exchange tube has a flattened, non-round cross-section.
6. A heat exchanger as recited in claim 5 wherein said at least one
heat exchange tube has a flattened, rectangular cross-section.
7. A heat exchanger as recited in claim 5 wherein said at least one
heat exchange tube has a flattened, generally oval
cross-section.
8. A heat exchanger as recited in claim 1 wherein each of said
plurality of channels defines a flow path having a non-circular
cross-section.
9. A heat exchanger as recited in claim 8 wherein each of said
plurality of channels defines a flow path is selected from a group
of a rectangular, triangular or trapezoidal cross-section.
10. A heat exchanger as recited in claim 1 wherein each of said
plurality of channels defines a flow path having a circular
cross-section.
11. A heat exchanger as recited in claim 1 wherein said first
opening comprises a plurality of openings.
12. A refrigerant vapor compression system comprising: a
compressor, a condenser and an evaporative heat exchanger connected
in fluid flow communication in a refrigerant circuit whereby high
pressure refrigerant vapor passes from said compressor to said
condenser, high pressure refrigerant passes from said condenser to
said evaporative heat exchanger, and low pressure refrigerant vapor
passes from said evaporative heat exchanger to said compressor;
characterized in that said evaporative heat exchanger includes: an
inlet header and an outlet header, each in fluid flow communication
with the refrigerant circuit, said inlet header defining a chamber
for receiving refrigerant from the refrigerant circuit; at least
one heat exchange tube having an inlet opening and an outlet
opening and having a plurality of discrete fluid flow paths
extending from the inlet opening to the outlet opening, the outlet
opening in fluid flow communication with said outlet header; and a
connector having an inlet end and an outlet end and defining a
fluid flow path extending from said inlet end to said outlet end,
said inlet end in fluid flow communication with the chamber of said
header through a first opening and said outlet end in fluid
communication with the inlet opening of said at least one heat
exchange tube through a second opening, said first opening having a
relatively small flow area.
13. A refrigerant vapor compression system as recited in claim 12
wherein said first opening of said connector comprises an expansion
orifice.
14. A refrigerant vapor compression system as recited in claim 12
wherein the fluid flow path of said connector comprises a divergent
fluid flow path expanding in cross-section in the direction of
fluid flow therethrough from said first opening to said second
opening.
15. A refrigerant vapor compression system as recited in claim 14
wherein said first opening of said connector comprises an expansion
orifice.
16. A refrigerant vapor compression system as recited in claim 12
wherein said at least one heat exchange tube has a flattened,
non-round cross-section.
17. A refrigerant vapor compression system as recited in claim 16
wherein said at least one heat exchange tube has a flattened,
rectangular cross-section.
18. A refrigerant vapor compression system as recited in claim 16
wherein said at least one heat exchange tube has a flattened,
generally oval cross-section.
19. A refrigerant vapor compression system as recited in claim 12
wherein each of said plurality of channels defines a flow path
having a non-circular cross-section.
20. A refrigerant vapor compression system as recited in claim 12
wherein each of said plurality of channels defines a flow path is
selected from a group of a rectangular, triangular or trapezoidal
cross-section.
21. A refrigerant vapor compression system as recited in claim 12
wherein each of said plurality of channels defines a flow path
having a circular cross-section.
22. A refrigerant vapor compression system as recited in claim 12
wherein said heat exchanger comprises a single-pass heat
exchanger.
23. A refrigerant vapor compression system as recited in claim 12
wherein said heat exchanger comprises a multi-pass heat
exchanger.
24. A refrigerant vapor compression system as recited in claim 12
wherein said heat exchanger comprises a condenser.
25. A refrigerant vapor compression system as recited in claim 12
wherein said heat exchanger comprises an evaporator.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] Reference is made to and this application claims priority
from and the benefit of U.S. Provisional Application Ser. No.
60/649,269, filed Feb. 2, 2005, and entitled MINI-CHANNEL HEAT
EXCHANGER WITH EXPANSION CONNECTOR, which application is
incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to heat exchangers having a
plurality of parallel tubes extending between a first header and a
second header, also sometimes referred to as manifolds, and, more
particularly, to providing fluid expansion within the header of a
heat exchanger for improving distribution of two-phase flow through
the parallel tubes of the heat exchanger, for example a heat
exchanger in a refrigerant compression system.
BACKGROUND OF THE INVENTION
[0003] Refrigerant vapor compression systems are well known in the
art. Air conditioners and heat pumps employing refrigerant vapor
compression cycles are commonly used for cooling or cooling/heating
air supplied to a climate controlled comfort zone within a
residence, office building, hospital, school, restaurant or other
facility. Refrigeration vapor compression systems are also commonly
used for cooling air or other secondary fluid to provide a
refrigerated environment for food items and beverage products
within, for instance, display cases in supermarkets, convenience
stores, groceries, cafeterias, restaurants and other food service
establishments.
[0004] Conventionally, these refrigerant vapor compression systems
include a compressor, a condenser, an expansion device, and an
evaporator connected in refrigerant flow communication. The
aforementioned basic refrigerant system components are
interconnected by refrigerant lines in a closed refrigerant circuit
and arranged in accord with the vapor compression cycle employed.
An expansion device, commonly an expansion valve or a fixed-bore
metering device, such as an orifice or a capillary tube, is
disposed in the refrigerant line at a location in the refrigerant
circuit upstream, with respect to refrigerant flow, of the
evaporator and downstream of the condenser. The expansion device
operates to expand the liquid refrigerant passing through the
refrigerant line running from the condenser to the evaporator to a
lower pressure and temperature. In doing so, a portion of the
liquid refrigerant traversing the expansion device expands to
vapor. As a result, in conventional refrigerant vapor compression
systems of this type, the refrigerant flow entering the evaporator
constitutes a two-phase mixture. The particular percentages of
liquid refrigerant and vapor refrigerant depend upon the particular
expansion device employed and the refrigerant in use, for example
R12, R22, R134a, R404A, R410A, R407C, R717, R744 or other
compressible fluid.
[0005] In some refrigerant vapor compression systems, the
evaporator is a parallel tube heat exchanger. Such heat exchangers
have a plurality of parallel refrigerant flow paths therethrough
provided by a plurality of tubes extending in parallel relationship
between an inlet header and an outlet header. The inlet header
receives the refrigerant flow from the refrigerant circuit and
distributes it amongst the plurality of flow paths through the heat
exchanger. The outlet header serves to collect the refrigerant flow
as it leaves the respective flow paths and to direct the collected
flow back to the refrigerant line for a return to the compressor in
a single pass heat exchanger or through an additional bank of heat
exchange tubes in a multi-pass heat exchanger.
[0006] Historically, parallel tube heat exchangers used in such
refrigerant compression systems have used round tubes, typically
having a diameter of 1/2 inch, 3/8 inch or 7 millimeters. More
recently, flat, rectangular or oval shape, multi-channel tubes are
being used in heat exchangers for refrigerant vapor compression
systems. Each multi-channel tube has a plurality of flow channels
extending longitudinally in parallel relationship the length of the
tube, each channel providing a small cross-sectional flow area
refrigerant path. Thus, a heat exchanger with multi-channel tubes
extending in parallel relationship between the inlet and outlet
headers of the heat exchanger will have a relatively large number
of small cross-sectional flow area refrigerant paths extending
between the two headers. In contrast, a parallel tube heat
exchanger with conventional round tubes will have a relatively
small number of large flow area flow paths extending between the
inlet and outlet headers.
[0007] Non-uniform distribution, also referred to as
maldistibution, of two-phase refrigerant flow is a common problem
in parallel tube heat exchangers which adversely impacts heat
exchanger efficiency. Two-phase maldistribution problems are caused
by the difference in density of the vapor phase refrigerant and the
liquid phase refrigerant present in the inlet header due to the
expansion of the refrigerant as it traversed the upstream expansion
device.
[0008] One solution to control refrigeration flow distribution
through parallel tubes in an evaporative heat exchanger is
disclosed in U.S. Pat. No. 6,502,413, Repice et al. In the
refrigerant vapor compression system disclosed therein, the high
pressure liquid refrigerant from the condenser is partially
expanded in a conventional in-line expansion device upstream of the
heat exchanger inlet header to a lower pressure refrigerant.
Additionally, a restriction, such as a simple narrowing in the tube
or an internal orifice plate disposed within the tube, is provided
in each tube connected to the inlet header downstream of the tube
inlet to complete the expansion to a low pressure, liquid/vapor
refrigerant mixture after entering the tube.
[0009] Another solution to control refrigeration flow distribution
through parallel tubes in an evaporative heat exchanger is
disclosed in Japanese Patent No. JP4080575, Kanzaki et al. In the
refrigerant vapor compression system disclosed therein, the high
pressure liquid refrigerant from the condenser is also partially
expanded in a conventional in-line expansion device to a lower
pressure refrigerant upstream of a distribution chamber of the heat
exchanger. A plate having a plurality of orifices therein extends
across the chamber. The lower pressure refrigerant expands as it
passes through the orifices to a low pressure liquid/vapor mixture
downstream of the plate and upstream of the inlets to the
respective tubes opening to the chamber.
[0010] Japanese Patent No. 6241682, Massaki et al., discloses a
parallel flow tube heat exchanger for a heat pump wherein the inlet
end of each multichannel tube connecting to the inlet header is
crushed to form a partial throttle restriction in each tube just
downstream of the tube inlet. Japanese Patent No. JP8233409,
Hiroaki et al., discloses a parallel flow tube heat exchanger
wherein a plurality of flat, multi-channel tubes connect between a
pair of headers, each of which has an interior which decreases in
flow area in the direction of refrigerant flow as a means to
uniformly distribute refrigerant to the respective tubes. Japanese
Patent No. JP2002022313, Yasushi, discloses a parallel tube heat
exchanger wherein refrigerant is supplied to the header through an
inlet tube that extends along the axis of the header to terminate
short of the end the header whereby the two phase refrigerant flow
does not separate as it passes from the inlet tube into an annular
channel between the outer surface of the inlet tube and the inside
surface of the header. The two phase refrigerant flow thence passes
into each of the tubes opening to the annular channel.
[0011] Obtaining uniform refrigerant flow distribution amongst the
relatively large number of small cross-sectional flow area
refrigerant flow paths is even more difficult than it is in
conventional round tube heat exchangers and can significantly
reduce heat exchanger efficiency.
SUMMARY OF THE INVENTION
[0012] It is a general object of the invention to reduce
maldistribution of fluid flow in a heat exchanger having a
plurality of multi-channel tubes extending between a first header
and a second header.
[0013] It is an object of one aspect of the invention to reduce
maldistribution of refrigerant flow in a refrigerant vapor
compression system heat exchanger having a plurality of
multi-channel tubes extending between a first header and a second
header.
[0014] It is an object of one aspect of the invention to distribute
refrigerant to the individual channels of an array of multi-channel
tubes in a relatively uniform manner.
[0015] It is an object of another aspect of the invention to
provide for distribution and expansion of the refrigerant in a
refrigerant vapor compression system heat exchanger having a
plurality of multi-channel tubes as the refrigerant flow passes
from a header to the individual channels of an array of
multi-channel tubes.
[0016] In one aspect of the invention, a heat exchanger is provided
having a header defining a chamber for receiving a fluid and at
least one heat exchange tube having a plurality of fluid flow paths
therethrough from an inlet end to an outlet end of the tube and
having an inlet opening to the plurality of fluid flow paths. A
connector has an inlet end in fluid flow communication with the
chamber of the header through a first opening and an outlet end in
fluid communication with the inlet opening of said at least one
heat exchange tube through a second opening. The connector defines
a fluid flow path extending from its inlet end to its outlet end.
In an embodiment, the flow path through the connector may be
divergent in the direction of fluid flow therethrough. The first
opening has a relatively small flow area so as to provide a flow
restriction through which fluid passes in flowing from the chamber
of the header to the flow paths of the heat exchange tube.
[0017] In another aspect of the invention, a refrigerant vapor
compression system includes a compressor, a condenser and an
evaporative heat exchanger connected in refrigerant flow
communication whereby high pressure refrigerant vapor passes from
the compressor to the condenser, high pressure refrigerant liquid
passes from the condenser to the evaporative heat exchanger, and
low pressure refrigerant vapor passes from the evaporative heat
exchanger to the compressor. The evaporative heat exchanger
includes an inlet header and an outlet header, and a plurality of
heat exchange tubes extending between the headers. The inlet header
defines a chamber for receiving liquid refrigerant from a
refrigerant circuit. Each heat exchange tube has an inlet end, an
outlet end, and a plurality of fluid flow paths extending from an
inlet opening at the inlet end to an outlet opening at the outlet
end of the tube. A connector has an inlet end in fluid flow
communication with the chamber of the inlet header through a first
opening and has an outlet end in fluid flow communication through a
second opening with the inlet opening of a heat exchange tube. The
connector defines a fluid flow path extending from its inlet end to
its outlet end. In an embodiment, the flow path through the
connector may be divergent in the direction of fluid flow
therethrough. The first opening has a relatively small
cross-sectional flow area so as to provide a flow restriction
through which fluid passes in flowing from the chamber of the
header to the flow paths of the heat exchange tube.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] For a further understanding of these and objects of the
invention, reference will be made to the following detailed
description of the invention which is to be read in connection with
the accompanying drawing, where:
[0019] FIG. 1 is a perspective view of an embodiment of a heat
exchanger in accordance with the invention;
[0020] FIG. 2 is a perspective view, partly sectioned, taken along
line 2-2 of FIG. 1;
[0021] FIG. 3 is a sectioned elevation view taken along line 3-3 of
FIG. 2;
[0022] FIG. 4 is a sectioned view taken along line 4-4 of FIG.
3;
[0023] FIG. 5 is a sectioned view taken along line 5-5 of FIG.
3;
[0024] FIG. 6 is a perspective view, partly sectioned, of an
another embodiment of a heat exchanger in accordance with the
invention;
[0025] FIG. 7 is a sectioned view taken along line 7-7 of FIG.
6;
[0026] FIG. 8 is a sectioned view taken along line 8-8 of FIG.
7;
[0027] FIG. 9 is a schematic illustration of a refrigerant vapor
compression system incorporating the heat exchanger of the
invention;
[0028] FIG. 10 is a schematic illustration of another refrigerant
vapor compression system incorporating the heat exchanger of the
invention;
[0029] FIG. 11 is an elevation view, partly in section, of an
embodiment of a multi-pass evaporator in accordance with the
invention; and
[0030] FIG. 12 is an elevation view, partly in section, of an
embodiment of a multi-pass condenser in accordance with the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] The heat exchanger 10 of the invention will be described in
general herein with reference to the illustrative single pass,
parallel-tube embodiment of a multi-channel tube heat exchanger as
depicted in FIG. 1. In the illustrative embodiment of the heat
exchanger 10 depicted in FIG. 1, the heat exchange tubes are shown
arranged in parallel relationship extending generally vertically
between a generally horizontally extending inlet header 20 and a
generally horizontally extending outlet header 30. However, the
depicted embodiment is illustrative and not limiting of the
invention. It is to be understood that the invention described
herein may be practiced on various other configurations of the heat
exchanger 10. For example, the heat exchange tubes may be arranged
in parallel relationship extending generally horizontally between a
generally vertically extending inlet header and a generally
vertically extending outlet header. As a further example, the heat
exchanger could have a toroidal inlet header and a toroidal outlet
header of a different diameter with the heat exchange tubes extend
either somewhat radially inwardly or somewhat radially outwardly
between the toroidal headers. The heat exchange tubes may also be
arranged in parallel tube, multi-pass embodiments, as will be
discussed in further detail later herein with reference to FIGS. 11
and 12.
[0032] Referring now to FIGS. 1-5 in particular, the heat exchanger
10 includes an inlet header 20, an outlet header 30, and a
plurality of longitudinally extending multi-channel heat exchanger
tubes 40 thereby providing a plurality of fluid flow paths between
the inlet header 20 and the outlet header 30. Each heat exchange
tube 40 has an inlet 43 at one end in fluid flow communication to
the inlet header 20 through a connector 50 and an outlet at its
other end in fluid flow communication to the outlet header 30. Each
heat exchange tube 40 has a plurality of parallel flow channels 42
extending longitudinally, i.e. along the axis of the tube, the
length of the tube thereby providing multiple, independent,
parallel flow paths between the inlet of the tube and the outlet of
the tube. Each multi-channel heat exchange tube 40 is a "flat" tube
of, for instance, rectangular or oval cross-section, defining an
interior which is subdivided to form a side-by-side array of
independent flow channels 42. The flat, multi-channel tubes 40 may,
for example, have a width of fifty millimeters or less, typically
twelve to twenty-five millimeters, and a height of about two
millimeters or less, as compared to conventional prior art round
tubes having a diameter of 1/2 inch, 3/8 inch or 7 mm. The tubes 40
are shown in drawings hereof, for ease and clarity of illustration,
as having twelve channels 42 defining flow paths having a circular
cross-section. However, it is to be understood that in commercial
applications, such as for example refrigerant vapor compression
systems, each multi-channel tube 40 will typically have about ten
to twenty flow channels 42, but may have a greater or a lesser
multiplicity of channels, as desired. Generally, each flow channel
42 will have a hydraulic diameter, defined as four times the flow
area divided by the perimeter, in the range from about 200 microns
to about 3 millimeters. Although depicted as having a circular
cross-section in the drawings, the channels 42 may have a
rectangular, triangular, trapezoidal cross-section or any other
desired non-circular cross-section.
[0033] Each of the plurality of heat exchange tubes 40 of the heat
exchanger 10 has its inlet end 43 inserted into a connector 50,
rather than directly into the chamber 25 defined within the inlet
header 20. Each connector 50 has an inlet end 52 and an outlet end
54 and defines a fluid flow path 55 extending from the inlet end 52
to the outlet end 54. The inlet end 52 is in fluid flow
communication with the chamber 25 of the inlet header 20 through a
first opening 51. The outlet end 54 is in fluid communication
through a second opening 53 with the inlet openings 41 of the
channels 42 at the inlet end of the associated heat transfer tube
40 received therein. The first opening 51 at the inlet end 52 of
each connector 50 has a relatively small cross-sectional flow area.
Therefore, the connectors 50 provide a plurality of flow
restrictions, at least one associated with each heat transfer tube
40, that provide uniformity in pressure drop in the fluid flowing
from the chamber 25 of the header 20 into the fluid flow path 55
within the connector 50, thereby ensuring a relatively uniform
distribution of fluid amongst the individual tubes 40 operatively
associated with the header 20.
[0034] In the embodiment depicted in FIGS. 1, 2 and 3, the inlet
header 20 comprises a longitudinally elongated, hollow, closed end
cylinder having a circular cross-section. The inlet end 52 of each
connector 50 is mated with a corresponding slot 26 provided in and
extending through the wall of the inlet header 20 with the inlet
end 52 of the connector 50 inserted into its corresponding slot.
Each connector may be brazed, welded, soldered, adhesively bonded,
diffusion bonded or otherwise secured in a corresponding mating
slot in the wall of the header 20. However, the inlet header 20 is
not limited to the depicted configuration. For example, the header
20 might comprise a longitudinally elongated, hollow, closed end
cylinder having an elliptical cross-section or a longitudinally
elongated, hollow, closed end pipe having a square, rectangular,
hexagonal, octagonal, or other cross-section.
[0035] In the embodiment depicted in FIGS. 6, 7 and 8, the inlet
header 20 comprises a longitudinally elongated, hollow, closed end,
half cylinder shell having a generally semi-circular cross-section
and a block-like insert 58 that is brazed, welded, adhesively
bonded or otherwise secured to the open face of the half cylinder
shell. In this embodiment, instead of a plurality of connectors 50,
the longitudinally, extending block-like insert 58 forms a single
connector 50. A plurality of longitudinally spaced, parallel flow
paths 55 is formed within the block-like structure of the connector
50. Each flow path 55 has an inlet end 52 having at least one
relatively small flow area inlet opening 51 in fluid communication
with a fluid chamber 25 defined within the header 20 and an outlet
end 54 having an opening 53 adapted to receive the inlet end 42 of
a heat exchange tube 40. Therefore, in this embodiment, a plurality
of heat exchange tubes 40 are connected to the header by means of a
single block-like connector 50. The block-like insert 58 provides a
connector 50 having a plurality of flow restrictions, with at least
one relatively small flow area opening 51 in operative association
with each heat transfer tube 40, that provide uniformity in
pressure drop in the fluid flowing from the chamber 25 of the
header 20 into the fluid flow path 55 within the connector 50,
thereby ensuring a relatively uniform distribution of fluid amongst
the individual tubes 40 operatively associated with the header
20.
[0036] In the embodiment depicted in FIGS. 2, 3 and 5, only one
first opening 51 of relatively small flow area is provided in the
inlet end 52 of each connector 50. However, it is to be understood
that, if desired, more than one first opening 51 of relatively
small flow area may be provided at the inlet end 52 of the
connector 50. For example, when the heat exchange tubes are
relatively wide and/or have a relatively large number of channels,
it may be desirable to have two, three or even more relatively
small flow area first openings 51 disposed at spaced intervals in
the inlet end 52 of the connector 50, such as illustrated in FIGS.
6, 7 and 8, to ensure uniform distribution of fluid flow to the
multiplicity of flow channels 42 of the tube 40 inserted in the
outlet end 54 of the connector 50.
[0037] The fluid flow path 55 extending from the inlet opening 51
at the inlet end 52 of the connector 50 to the outlet opening 53 at
the outlet end 54 of the connector 50 may, as best depicted in FIG.
3 and in FIG. 7, diverge in the direction of fluid flow from the
inlet opening 51 to the outlet opening 53. A divergent flow path
assists in distributing the fluid flowing through the flow path 55
uniformly amongst the various flow channels 42 of the heat exchange
tube 40 inserted into the outlet end 54 of the connector 50,
particularly in refrigerant flow applications wherein the fluid is
a liquid refrigerant and vapor refrigerant mixture or expands to a
liquid refrigerant/vapor refrigerant mixture as the fluid passes
through the relatively small flow area opening or openings 51.
[0038] Referring now to FIGS. 9 and 10, there is depicted
schematically a refrigerant vapor compression system 100 having a
compressor 60, the heat exchanger 10A, functioning as a condenser,
and the heat exchanger 10B, functioning as an evaporator, connected
in a closed loop refrigerant circuit by refrigerant lines 12, 14
and 16. As in conventional refrigerant vapor compression systems,
the compressor 60 circulates hot, high pressure refrigerant vapor
through refrigerant line 12 into the inlet header 120 of the
condenser 10A, and thence through the heat exchanger tubes 140 of
the condenser 10A wherein the hot refrigerant vapor condenses to a
liquid as it passes in heat exchange relationship with a cooling
fluid, such as ambient air which is passed over the heat exchange
tubes 140 by a condenser fan 70. The high pressure, liquid
refrigerant collects in the outlet header 130 of the condenser 10A
and thence passes through refrigerant line 14 to the inlet header
20 of the evaporator 10B. The refrigerant thence passes through the
heat exchanger tubes 40 of the evaporator 10B wherein the
refrigerant is heated as it passes in heat exchange relationship
with air to be cooled which is passed over the heat exchange tubes
40 by an evaporator fan 80. The refrigerant vapor collects in the
outlet header 30 of the evaporator 10B and passes therefrom through
refrigerant line 16 to return to the compressor 60 through the
suction inlet thereto. Although the exemplary refrigerant vapor
compression cycles illustrated in FIGS. 9 and 10 are simplified air
conditioning cycles, it is to be understood that the heat exchanger
of the invention may be employed in refrigerant vapor compression
systems of various designs, including, without limitation, heat
pump cycles, economized cycles and refrigeration cycles.
[0039] In the embodiment depicted in FIG. 9, the condensed
refrigerant liquid passes from the condenser 10A directly to the
evaporator 10B without traversing an expansion device. Thus, in
this embodiment the refrigerant typically enters the inlet header
20 of the evaporative heat exchanger 10B as a high pressure, liquid
refrigerant, not as a fully expanded, low pressure, refrigerant
liquid/vapor mixture, as in conventional refrigerant compression
systems. Thus, in this embodiment, expansion of the refrigerant
occurs within the evaporator 10B of the invention as the
refrigerant passes through the relatively small area opening or
openings 51 at the inlet end 52 into the flow path 55 of the
connector 50, thereby ensuring that expansion occurs only after the
distribution has been achieved in a substantially uniform
manner.
[0040] In the embodiment depicted in FIG. 10, the condensed
refrigerant liquid passes through an expansion valve 50 operatively
associated with the refrigerant line 14 as it passes from the
condenser 10A to the evaporator 10B. In the expansion valve 50, the
high pressure, liquid refrigerant is partially expanded to lower
pressure and lower temperature, liquid refrigerant or a
liquid/vapor refrigerant mixture. In this embodiment, the final
expansion of the refrigerant is completed within the evaporator 10B
as the refrigerant passes through the relatively small flow area
opening or openings 51 at the inlet end 52 into the flow path 55 of
the connector 50. Partial expansion of the refrigerant in an
expansion valve upstream of the inlet header 20 to the evaporator
10B may be advantageous when the cross-sectional flow area of the
openings 51, can not be made small enough to ensure complete
expansion as the liquid passes through the openings 51 or when an
expansion valve is used as a flow control device.
[0041] Referring now to FIG. 11, the heat exchanger 10 of the
invention is depicted in a multi-pass, evaporator embodiment. In
the illustrated multi-pass embodiment, the inlet header 20 is
partitioned into a first chamber 20A and a second chamber 20B, the
outlet header is also partitioned into a first chamber 30A and a
second chamber 30B, and the heat exchange tubes 40 are divided into
three banks 40A, 40B and 40C. The tubes of the first tube bank 40A
have inlet ends inserted into respective connectors 50A that are
open into the first chamber 20A of the inlet header 20 and outlet
ends are open to the first chamber 30A of the outlet header 30. The
tubes of the second tube bank 40B have inlet ends inserted into
respective connectors 50B that are open into the first chamber 30A
of the outlet header 30 and outlet ends are open to the second
chamber 20B of the inlet header 20. The tubes of the third tube
bank 40C have inlet ends inserted into respective connectors 50C
that open into the second chamber 20B of the inlet header 20 and
outlet ends are open to the second chamber 30B of the outlet header
30. In this manner, refrigerant entering the heat exchanger from
refrigerant line 14 passes in heat exchange relationship with air
passing over the exterior of the heat exchange tubes 40 three
times, rather than once as in a single pass heat exchanger. In
accord with the invention, the inlet end 43 of each of the tubes of
the first, second and third tube banks 40A, 40B and 40C is inserted
into the outlet end 54 of its associated connector 50 whereby the
channels 42 of each of the tubes 40 will receive a relatively
uniform distribution of expanded refrigerant liquid/vapor mixture.
Distribution and expansion of the refrigerant occurs as the
refrigerant passes from the header into the connector through the
relatively small cross-sectional flow area opening 51, not only as
the refrigerant passes into the first tube bank 40A, but also as
the refrigerant passes into the second tube bank 40B and into the
third tube bank 40C, thereby ensuring more uniform distribution of
the refrigerant liquid/vapor upon entering the flow channels of the
tubes of each tube bank.
[0042] Referring now to FIG. 12, the heat exchanger 10 of the
invention is depicted in a multi-pass, condenser embodiment. In the
illustrated multi-pass embodiment, the inlet header 120 is
partitioned into a first chamber 120A and a second chamber 120B,
the outlet header 130 is also partitioned into a first chamber 130A
and a second chamber 130B, and the heat exchange tubes 140 are
divided into three banks 140A, 140B and 140C. The tubes of the
first tube bank 140A have inlet end openings into the first chamber
120A of the inlet header 120 and outlet end openings to the first
chamber 130A of the outlet header 130. The tubes of the second tube
bank 140B have inlet ends inserted into respective connectors 50B
that are open into the first chamber 130A of the outlet header 130
and outlet ends that are open to the second chamber 120B of the
inlet header 120. The tubes of the third tube bank 140C have inlet
ends inserted into respective connectors 50C that are open into the
second chamber 120B of the inlet header 120 and outlet ends are
open to the second chamber 130B of the outlet header 130. In this
manner, refrigerant entering the condenser from refrigerant line 12
passes in the heat exchange relationship with air passing over the
exterior of the heat exchange tubes 140 three times, rather than
once as in a single pass heat exchanger. The refrigerant entering
the first chamber 120A of the inlet header 120 is entirely high
pressure, refrigerant vapor directed from the compressor outlet via
refrigerant line 14. However, the refrigerant entering the second
tube bank and the third tube bank typically will be a liquid/vapor
mixture as refrigerant partially condenses in passing through the
first and second tube banks. In accord with the invention, the
inlet end of each of the tubes of the second and third tube banks
140B, 140C is inserted into the outlet ends of their associated
connectors 50B, 50C whereby the channels 42 of each of the tubes
will receive a relatively uniform distribution of expanded
refrigerant liquid/vapor mixture. Obviously, it has to be noted
that pressure drop through the openings 51 has to be limited to not
exceed a predetermined threshold for the condenser applications, in
order not to compromise the heat exchanger efficiency. Further, a
person ordinarily skilled in the art would understand that other
multi-pass arrangements for condensers and evaporators are also
within the scope of the invention.
[0043] While the present invention has been particularly shown and
described with reference to the preferred mode as illustrated in
the drawing, it will be understood by one skilled in the art that
various changes in detail may be effected therein without departing
from the spirit and scope of the invention as defined by the
claims.
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