U.S. patent application number 12/426980 was filed with the patent office on 2010-10-21 for microchannel heat exchanger.
This patent application is currently assigned to HAMILTON SUNDSTRAND CORPORATION. Invention is credited to Abbas A. Alahyari, Mohsen Farzad.
Application Number | 20100263847 12/426980 |
Document ID | / |
Family ID | 42931525 |
Filed Date | 2010-10-21 |
United States Patent
Application |
20100263847 |
Kind Code |
A1 |
Alahyari; Abbas A. ; et
al. |
October 21, 2010 |
MICROCHANNEL HEAT EXCHANGER
Abstract
Disclosed is a microchannel heat exchanger (10) including at
least one manifold (14) for distributing fluid and a plurality of
tubes (12) extending from the at least one manifold (14). At least
one tube (12) of the plurality of tubes (12) has a substantially
curvilinear cross-section and includes a plurality of ports (24)
extending from a first end of each tube (12) to a second end of
each tube (12), the ports (24) capable of carrying fluid
therethrough. A plurality of fins (16) are located along a length
of the plurality of tubes (24). Further disclosed is a method for
extracting thermal energy from a flow via a microchannel heat
exchanger (10).
Inventors: |
Alahyari; Abbas A.;
(Manchester, CT) ; Farzad; Mohsen; (Glastonbury,
CT) |
Correspondence
Address: |
Cantor Colburn LLP - Hamilton Sundstrand
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
HAMILTON SUNDSTRAND
CORPORATION
Windsor Locks
CT
|
Family ID: |
42931525 |
Appl. No.: |
12/426980 |
Filed: |
April 21, 2009 |
Current U.S.
Class: |
165/173 ;
165/182 |
Current CPC
Class: |
F28F 1/00 20130101; F28F
2260/02 20130101; F28F 1/32 20130101; F28F 2250/02 20130101; F28F
1/022 20130101; F28D 1/05383 20130101; F28D 1/05333 20130101; F28F
1/126 20130101 |
Class at
Publication: |
165/173 ;
165/182 |
International
Class: |
F28F 9/02 20060101
F28F009/02; F28F 1/24 20060101 F28F001/24 |
Claims
1. A microchannel heat exchanger (10) comprising: at least one
manifold (14) for distributing fluid; a plurality of tubes (12)
extending from the at least one manifold (14), at least one tube
(12) of the plurality of tubes (12) having: a substantially
curvilinear cross-section; and a plurality of ports (24) extending
from a first end of each tube (12) to a second end of each tube
(12), the ports (24) capable of carrying fluid therethrough; and a
plurality of fins (16) disposed along a length of the plurality of
tubes (12).
2. The microchannel heat exchanger (10) of claim 1 wherein the at
least one tube (12) of the plurality of tubes (12) includes a
hollow portion (28) extending along its length, the plurality of
ports (24) disposed between the hollow portion (28) and an exterior
wall (30) of the tube (12).
3. The microchannel heat exchanger (10) of claim 2 wherein the
hollow portion (28) is plugged at an end to prevent fluid from
entering the hollow portion (28).
4. The microchannel heat exchanger (10) of claim 1 wherein the at
least one tube (12) of the plurality of tubes (12) is substantially
circular in cross-section.
5. The microchannel heat exchanger (10) of claim 1 wherein the at
least one tube (12) of the plurality of tubes (12) has a
substantially airfoil-shaped cross-section.
6. The microchannel heat exchanger (10) of claim 1 wherein at least
two tubes (12) of the plurality of tubes (12) are connected at one
end via a u-shaped connector (40).
7. The microchannel heat exchanger (10) of claim 1 wherein at least
two tubes (12) of the plurality of tubes (12) are configured to
improve interactions with airflow therebetween to enhance heat
transfer.
8. The microchannel heat exchanger (10) of claim 1 wherein each fin
(16) of the plurality of fins (16) includes at least one fin
opening (20) through which at least one tube (12) of the plurality
of tubes (12) passes.
9. The microchannel heat exchanger (10) of claim 1 wherein the at
least one fin opening (20) includes a collar (22) to determine
spacing between adjacent fins (16) of the plurality of fins
(16).
10. The microchannel heat exchanger (10) of claim 1 wherein at
least one fin (16) of the plurality of fins (16) includes at least
one louver (18) to enhance heat transfer capability of the
plurality of fins (16).
11. The microchannel heat exchanger (10) of claim 1 wherein each
port (24) of the plurality of ports (24) is about 0.1 mm to about 5
mm in width.
12. A method for extracting thermal energy from a flow comprising:
urging a coolant from a manifold (14) into a plurality of tubes
(12) in flow communication with the manifold (14), at least one
tube (12) of the plurality of tubes (12) including: a substantially
curvilinear cross-section; and a plurality of ports (24) extending
from a first end of each tube (12) to a second end of each tube
(12), the ports (24) capable of carrying fluid therethrough; urging
the coolant along a length of the tubes (12) via the plurality of
ports (24); urging a flow across a plurality of fins (16) in
thermal communication with the plurality of tubes (12); and
transferring thermal energy to the coolant via the plurality of
fins (16).
13. The method of claim 12 wherein the at least one tube (12) of
the plurality of tubes (12) includes a hollow portion (28)
extending alone its length, the plurality of ports (24) disposed
between the hollow portion (28) and an exterior wall (30) of the
tube (12).
14. The method of claim 13 comprising plugging the hollow portion
(28) at an end to prevent fluid from entering the hollow portion
(28).
15. The method of claim 12 wherein the at least one tube (12) of
the plurality of tubes (12) is substantially circular in
cross-section.
16. The method of claim 12 wherein the at least one tube (12) of
the plurality of tubes (12) has a substantially airfoil-shaped
cross-section.
17. The method of claim 12 comprising: flowing the coolant through
a first tube (12) of the plurality of tubes (12); flowing the
coolant through a u-shaped connector (40) disposed between the
first tube (12) and a second tube (12) of the plurality of tubes
(12); and flowing the coolant through the second tube (12).
18. The method of claim 12 wherein at least two tubes (12) of the
plurality of tubes (12) are configured to improve interactions with
airflow therebetween to enhance heat transfer.
19. The method of claim 12 wherein each fin (16) of the plurality
of fins (16) includes at least one fin opening (20) through which
at least one tube (12) of the plurality of tubes (12) passes.
20. The method of claim 12 comprising urging the flow past at least
one louver (18) disposed in the plurality of fins (16) to enhance
heat transfer capability.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein generally relates to
microchannel heat exchangers. More specifically, this disclosure
relates to tube configurations for microchannel heat
exchangers.
[0002] Microchannel heat exchangers find use in a wide variety of
applications, including automotive, residential and aerospace. As
shown in FIG. 9, a typical microchannel heat exchanger 100 includes
a plurality of flat tubes 102 each having a plurality of ports 104
therethrough. The tubes 102 are typically arranged such that a flat
surface 106 of each tube 102 is substantially horizontal. Air flows
through an array of fins 108 which extend from the tubes 102, while
a liquid or two-phase refrigerant flows through the plurality of
ports 104. Due to the high density of fin 108 surface area and tube
102 surface area, during the heat exchange process, however, the
microchannel heat exchanger is subject to moisture and condensate
accumulation, and also frost accumulation. This problem is
magnified in the exchangers where the tubes 102 are arranged so
that the flat surface 106 is substantially horizontal as the
moisture collects and remains on the flat surfaces 106. The
moisture and frost accumulation makes operation of the heat
exchanger less efficient by increasing flow resistance and thermal
resistance through the heat exchanger. Further, the moisture
accumulation causes corrosion and pitting of the tube 102 surfaces,
thus decreasing their useful life. The art would well receive a
microchannel heat exchanger configuration which maintains the high
surface density of a typical microchannel heat exchanger while
reducing the efficiency-reducing moisture accumulation.
BRIEF DESCRIPTION OF THE INVENTION
[0003] According to one aspect of the invention, a microchannel
heat exchanger includes at least one manifold for distributing
fluid and a plurality of tubes extending from the at least one
manifold. At least one tube of the plurality of tubes has a
substantially curvilinear cross-section and includes a plurality of
ports extending from a first end of each tube to a second end of
each tube, the ports capable of carrying fluid therethrough. A
plurality of fins are located along a length of the plurality of
tubes.
[0004] According to another aspect of the invention, a method for
extracting thermal energy from a flow includes urging a coolant
from a manifold into a plurality of tubes in flow communication
with the manifold. At least one tube of the plurality of tubes has
a substantially curvilinear cross-section and includes a plurality
of ports extending from a first end of each tube to a second end of
each tube, the ports capable of carrying fluid therethrough. The
coolant is urged along a length of the tubes via the plurality of
ports. The flow is urged across a plurality of fins in thermal
communication with the plurality of tubes and thermal energy is
transferred to the coolant via the plurality of fins.
[0005] These and other advantages and features will become more
apparent from the following description taken in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWING
[0006] The subject matter, which is regarded as the invention, is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0007] FIG. 1 is a perspective view of an embodiment of a
microchannel heat exchanger;
[0008] FIG. 2 is another view of the microchannel heat exchanger of
FIG. 1;
[0009] FIG. 3 is an alternative embodiment of the microchannel heat
exchanger of FIG. 1;
[0010] FIG. 4 is a cross-sectional view of an embodiment of a tube
of a microchannel heat exchanger;
[0011] FIG. 5 is a cross-sectional view of another embodiment of a
tube of a microchannel heat exchanger;
[0012] FIG. 6 is a cross-sectional view of yet another embodiment
of a tube of a microchannel heat exchanger;
[0013] FIG. 7 is a cross-sectional view of another embodiment of a
microchannel heat exchanger;
[0014] FIG. 8 is a perspective view of a microchannel heat
exchanger having u-connecters disposed at tube ends; and
[0015] FIG. 9 is a perspective view of a typical microchannel heat
exchanger.
[0016] The detailed description explains embodiments of the
invention, together with advantages and features, by way of example
with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Illustrated in FIG. 1 is an embodiment of a microchannel
heat exchanger 10. The heat exchanger 10 includes a plurality of
tubes 12 extending from at least one manifold 14. Two manifolds 14
are illustrated in FIG. 1, but it is to be appreciated that other
quantities of manifolds 14, for example, one or three manifolds 14,
are contemplated within the present scope. Each tube 12 of the
plurality of tubes 12 is connected to the at least one manifold 14
by, for example, brazing, or other suitable connection means.
Disposed across the plurality of tubes 12 is an array of fins 16.
The fins 16 may be comprised of folded fins as shown in FIG. 2 or
individual fin plates 16 as shown in FIG. 3, and further may
include louvers 18 or similar enhancements to increase heat
transfer capability of the fins 16. As shown in FIG. 4, the fins 16
have fin openings 20 which may be made by, for example, a punching
operation. The fin openings 20 allow the passage of one tube 12 of
the plurality of tubes 12 therethrough. Each fin 16 may have
multiple fin openings 20 so that multiple tubes 12 may pass through
each fin 16. For example, as shown in FIG. 4, each fin 16 has two
fin openings 20 which allows for the passage of two tubes 12
through each fin 16. It is to be appreciated, however, that other
quantities of fin openings 20 may be disposed in each fin 16, for
example three or four fin openings 20. In some embodiments, the fin
openings 20 have a collar 22 extending at least partially around a
perimeter of the fin openings 20 to determine a spacing between
adjacent fins 16. In some embodiments, the fins 16 may be brazed to
the tubes 12 at each fin opening 20 to secure the fins 16 in
position relative to the tubes 12 and to improve thermal contact
between the fins 16 and the tubes 12.
[0018] In some embodiments, as shown in FIG. 4, each tube 12 of the
plurality of tubes 12 may have a substantially circular
cross-section, with a plurality of ports 24 arranged around a
central axis 26 of the tube 12 and in some embodiments extending
from a first end to a second end of the tube 12. The ports 24 are
about 0.1 mm to about 5 mm in width. As shown in FIG. 4, the ports
24 may be circular in cross-section, or, in some embodiments, as
shown in FIG. 5, the ports 24 may have cross sections which are
circular sector. It is to be appreciated that the port 24
cross-sectional shapes shown in FIGS. 4 and 5 are merely examples,
and that other cross-sectional shapes of the tubes are contemplated
within the present scope. Further, the shapes and sizes of ports 24
within a single tube 12 or throughout multiple tubes 12 of the
microchannel heat exchanger 10 may be varied to enhance performance
of the microchannel heat exchanger 10.
[0019] Referring again to FIG. 4, in some embodiments, the tube 12
may have a hollow portion 28 which extends through the tube 12
along its length. The hollow portion 28 may be circular in
cross-section as shown in FIG. 4, or may be another shape if so
desired. In the embodiment of FIG. 4, the hollow portion 28 is
located at the central axis 26, but it is to be appreciated that in
some embodiments the hollow portion 28 may be offset from the
central axis 26. In such embodiments, the ports 24 are arrayed
between the hollow portion 28 and an outer surface 30 of the tube
12. The hollow portion 28 reduces the amount of material necessary
to fabricate the tube 12, which may be formed by extrusion or other
suitable process. The hollow portion 28 is plugged at at least one
end of the tube 12 before operation of the microchannel heat
exchanger 10 to prevent refrigerant from bypassing the ports 24
and/or proceeding to flow through the hollow portion 28.
[0020] Referring now to FIG. 6, the tubes 12 may be have
cross-sectional shapes other than circular. For example, the as
shown in FIG. 6, the tubes 12 may have a teardrop or airfoil
cross-sectional shape. In some embodiments, the airfoil shaped
cross section may include the hollow portion 28 with the ports 24
arrayed between the hollow section 28 and the outer surface 30.
Tubes 12 having an airfoil or teardrop cross-section improve
pressure drop across the tubes 12, provide better heat transfer and
improve moisture drainage from the tubes 12.
[0021] Referring to FIG. 7, in configurations of the microchannel
heat exchanger 10 where multiple tubes 12 pass through each fin 16,
the tubes 12 are disposed closely to each other such that there are
interactions of the flows passing between the tubes 12 in, for
example, a first row 32 and a second row 34. To take advantage of,
and improve the interactions to enhance heat transfer, the shape
and/or positioning of the tubes 12 may be tuned. For example, tubes
12 in the second row 34 may be positioned such that they are
substantially between adjacent tubes 12 of the first row 32 so a
flow 36 directed at the tubes 12 of the second row 34 is not
shielded by the tubes 12 of the first row 32. Further, a trailing
edge 38 of tubes in the first row 32 may be turned toward an
adjacent tube 12 of the second row 34 thereby turning the flow 36
toward the tubes 12 of the second row 34 to improve heat
transfer.
[0022] In some embodiments, the microchannel heat exchanger 10 is a
multi-pass configuration, meaning that each tube 12 may pass
through the plurality of fins 16 more than once. As shown in FIG.
8, this may be accomplished by providing at least one u-shaped
connector 40 at at least one end of each tube 12. The connector 40
may be brazed to the tube 12 and is configured to direct
refrigerant flow from a first tube portion 42 through the connector
40 and redirects it into a second tube portion 44 to pass through
plurality of fins 16 again. In some embodiments, the first tube
portion 42 is disposed in the first row 32 and the second tube
portion 44 is disposed in the second row 34.
[0023] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *