U.S. patent application number 13/818386 was filed with the patent office on 2013-06-20 for microchannel heat exchanger fin.
This patent application is currently assigned to CARRIER CORPORATION. The applicant listed for this patent is Jack Leon Esformes, Arindom Joardar, Sunil S. Mehendale, Michael F. Taras. Invention is credited to Jack Leon Esformes, Arindom Joardar, Sunil S. Mehendale, Michael F. Taras.
Application Number | 20130153174 13/818386 |
Document ID | / |
Family ID | 44630291 |
Filed Date | 2013-06-20 |
United States Patent
Application |
20130153174 |
Kind Code |
A1 |
Taras; Michael F. ; et
al. |
June 20, 2013 |
MICROCHANNEL HEAT EXCHANGER FIN
Abstract
A heat exchanger includes a plurality of tubes (12), each tube
configured for a flow of fluid therethrough and one or more fins
located between adjacent tubes of the plurality of tubes. The one
or more fins are spaced by a fin pitch (Fp,18) and are configured
to improve thermal energy transfer between the plurality of tubes
and ambient air. Each fin includes a fin face extending between the
adjacent tubes, a substantially planar fin cap (22) connected to
the fin face secured to one or the tubes, and a fin radius (Rc,26)
connecting the fin face to the fin cap such that the fin radius is
reduced to promote condensate removal from the heat exchanger.
Inventors: |
Taras; Michael F.;
(Fayetteville, NY) ; Joardar; Arindom; (East
Syracuse, NY) ; Esformes; Jack Leon; (Jamesville,
NY) ; Mehendale; Sunil S.; (Manlius, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taras; Michael F.
Joardar; Arindom
Esformes; Jack Leon
Mehendale; Sunil S. |
Fayetteville
East Syracuse
Jamesville
Manlius |
NY
NY
NY
NY |
US
US
US
US |
|
|
Assignee: |
CARRIER CORPORATION
Farmington
CT
|
Family ID: |
44630291 |
Appl. No.: |
13/818386 |
Filed: |
August 9, 2011 |
PCT Filed: |
August 9, 2011 |
PCT NO: |
PCT/US11/47044 |
371 Date: |
February 22, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61376356 |
Aug 24, 2010 |
|
|
|
Current U.S.
Class: |
165/104.19 |
Current CPC
Class: |
F28F 3/027 20130101;
F28F 1/128 20130101; F28F 1/022 20130101; F28F 17/005 20130101;
F28F 2260/00 20130101; F28F 1/12 20130101 |
Class at
Publication: |
165/104.19 |
International
Class: |
F28F 1/12 20060101
F28F001/12 |
Claims
1. A heat exchanger comprising: a plurality of tubes, each tube
configured for a flow of fluid therethrough; one or more fins
disposed between adjacent tubes of the plurality of tubes, the one
or more fins spaced by a fin pitch (F.sub.P) and configured to
improve thermal energy transfer between the plurality of tubes and
ambient air, each fin including: a fin face extending between the
adjacent tubes; a substantially planar fin cap connected to the fin
face secured to one or the tubes; and a fin radius (R.sub.C)
connecting the fin face to the fin cap such R.sub.C is reduced to
promote condensate flow from the heat exchanger.
2. The heat exchanger of claim 1 such that a ratio of the fin
radius to the fin pitch, R.sub.C/F.sub.P, is between about 0.1 and
about 0.4.
3. The heat exchanger of claim 2, wherein the ratio of the fin
radius to the fin pitch, R.sub.C/F.sub.P, is between about 0.2 and
about 0.3.
4. The heat exchanger of claim 1, wherein each fin face includes
one or more louvers.
5. The heat exchanger of claim 4, wherein a ratio of a louver
height (L.sub.H) to a fin height (F.sub.H), L.sub.H/F.sub.H, is
between about 0.8 and about 0.95.
6. The heat exchanger of claim 5, wherein L.sub.H/F.sub.H, is
between about 0.85 and about 0.92.
7. The heat exchanger of claim 1, wherein each fin includes a fin
extension extending beyond a tube width.
8. The heat exchanger of claim 7, wherein the fin extension extends
laterally beyond the tube width and transversely at least partially
across a tube thickness.
9. The heat exchanger of claim 7, wherein the fin extension is
configured to direct moisture accumulated in the fin structure away
from the tubes.
10. The heat exchanger of claim 7, wherein a ratio of an extension
width (E.sub.W) to a fin width (F.sub.W), E.sub.W/F.sub.W is
between about 0.02 and about 0.1.
11. The heat exchanger of claim 10, wherein E.sub.W/F.sub.W is
between about 0.02 and about 0.04.
12. The heat exchanger of claim 7, wherein a ratio of a transverse
component (E.sub.T) of the fin extension to a tube thickness
(T.sub.T), E.sub.T/T.sub.T, is between about 0.05 and about
0.4.
13. The heat exchanger of claim 12, wherein E.sub.T/T.sub.T is
between about 0.05 and about 0.15.
14. The heat exchanger of claim 7, wherein a ratio of a transverse
component (E.sub.T) of the fin extension to a fin thickness
(F.sub.T), E.sub.T/F.sub.T, is between about 1 and about 3.
15. The heat exchanger of claim 14, wherein E.sub.T/F.sub.T, is
between about 1.75 and about 2.5.
16. The heat exchanger of claim 7, wherein a ratio of a transverse
component (E.sub.T) of the fin extension to the fin radius,
E.sub.T/R.sub.C, is between about 0.2 and about 2.
17. The heat exchanger of claim 1, wherein each fin of the one or
more fins spans two or more tubes along a fin width.
18. The heat exchanger of claim 17, wherein each fin includes a fin
notch in the fin face disposed substantially aligned with a tube
gap between two tubes of the two or more tubes.
19. The heat exchanger of claim 18, wherein a ratio of a notch
height (N.sub.H) to a tube pitch (T.sub.P), N.sub.H/T.sub.P, is
between about 0.15 and about 0.3.
20. The heat exchanger of claim 19, wherein N.sub.H/T.sub.P, is
between about 0.1 and about 0.2.
21. The heat exchanger of claim 1, wherein each tube of the
plurality of tubes, includes a through slot extending along a
length of the tube.
22. The heat exchanger of claim 21, wherein a ratio of a slot width
(S.sub.W) to a tube width (T.sub.W), S.sub.W/T.sub.W, is between
about 0.05 and about 0.2.
23. The heat exchanger of claim 21, wherein a ratio of slot length
(S.sub.L) to a tube length (T.sub.L), S.sub.L/T.sub.L, is between
about 0.8 and about 0.95.
24. A heat exchanger comprising: a plurality of tubes, each tube
configured for a flow of fluid therethrough; one or more fins
disposed between adjacent tubes of the plurality of tubes, the one
or more fins spaced by a fin pitch (Fp) and configured to improve
thermal energy transfer between the plurality of tubes and ambient
air, each fin including a fin extension extending beyond a tube
width.
25. The heat exchanger of claim 24, wherein the fin extension is
configured to direct moisture accumulated in the fin structure away
from the tubes.
26. The heat exchanger of claim 24, wherein a ratio of an extension
width (E.sub.W) to a fin width (F.sub.W), E.sub.W/F.sub.W is
between about 0.02 and about 0.1.
27. The heat exchanger of claim 26, wherein E.sub.W/F.sub.W is
between about 0.02 and about 0.04.
28. The heat exchanger of claim 24, wherein a ratio of a transverse
component (E.sub.T) of the fin extension to a tube thickness
(T.sub.T), E.sub.T/T.sub.T, is between about 0.05 and about
0.4.
29. The heat exchanger of claim 28, wherein E.sub.T/T.sub.T is
between about 0.05 and about 0.15.
30. The heat exchanger of claim 24, wherein a ratio of a transverse
component (E.sub.T) of the fin extension to a fin thickness
(F.sub.T), E.sub.T/F.sub.T, is between about 1 and about 3.
31. The heat exchanger of claim 30, wherein E.sub.T/F.sub.T, is
between about 1.75 and about 2.5.
32. The heat exchanger of claim 24, wherein each fin includes: a
fin face extending between the adjacent tubes and; a substantially
planar fin cap connected to the fin face secured to one or the
tubes; and a fin radius (R.sub.C) connecting the fin face to the
fin cap such that a ratio of the fin radius to the fin pitch,
R.sub.C/F.sub.P, is between about 0.1 and about 0.4.
33. The heat exchanger of claim 32, wherein the ratio of the fin
radius to the fin pitch, R.sub.C/F.sub.P, is between about 0.2 and
about 0.3.
34. The heat exchanger of claim 32, wherein each fin face includes
one or more louvers.
35. The heat exchanger of claim 34, wherein a ratio of a louver
height (L.sub.H) to a fin height (F.sub.H), L.sub.H/F.sub.H, is
between about 0.8 and about 0.95.
36. The heat exchanger of claim 35, wherein L.sub.H/F.sub.H, is
between about 0.85 and about 0.92.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to heat
exchangers. More specifically, the subject disclosure relates to
fin and tube configurations for microchannel heat exchangers.
[0002] Heating, ventilation, air conditioning and refrigeration
(HVAC & R) systems include heat exchangers to reject or accept
heat between the refrigerant circulating within the system and
surroundings. One type of the heat exchanger that has become
increasingly popular, due to its compactness, structural rigidity
and superior performance is a microchannel or minichannel heat
exchanger (MCHX) which includes two or more containment forms, such
as tubes, through which a cooling or heating fluid (such as
refrigerant or glycol solution) is circulated. The tubes typically
have a flattened cross-section and multiple parallel channels. Fins
are typically arranged to extend between the tubes to aid in the
transfer of thermal energy between the cooling/heating fluid and
the surrounding environment. The fins have a corrugated pattern,
incorporate louvers to boost heat transfer and are typically
secured to the tubes via brazing. Typical MCHX fin and tube
arrangements, however, have the disadvantage of retaining large
quantities of moisture, water or condensate, within the fin and
tube structure, due to their high compactness and thus increased
surface tension. The accumulated moisture accelerates corrosion of
the fin and tube structure which leads to decreased
thermo-hydraulic performance or effectiveness of the heat exchanger
and eventual failure of the heat exchanger when the tubes are
corroded sufficiently to be perforated, thus releasing the
cooling/heating fluid. Further, along with retention of moisture,
the typical structure leads to the buildup of corrodant substances
and mechanical stresses in the structure leading to stress
corrosion which further accelerates deterioration of the fin and
tube structure and resultant failure of the heat exchanger. The art
would well receive a fin and tube structure which reduces the
accumulation of moisture in the heat exchanger matrix thereby
reducing corrosion of the heat exchanger.
BRIEF DESCRIPTION OF THE INVENTION
[0003] According to one aspect of the invention, a heat exchanger
includes a plurality of tubes, each tube configured for a flow of
fluid therethrough and one or more fins located between adjacent
tubes of the plurality of tubes. The one or more fins are spaced by
a fin pitch (F.sub.P) and are configured to improve thermal energy
transfer between the plurality of tubes and ambient air. Each fin
includes a fin face extending between the adjacent tubes, a
substantially planar fin cap connected to the fin face secured to
one or the tubes, and a fin radius (R.sub.C) connecting the fin
face to the fin cap such that the fin radius is minimized to
promote removal of condensate from the heat exchanger.
[0004] According to another aspect of the invention, a heat
exchanger includes a plurality of tubes, each tube configured for a
flow of fluid therethrough. One or more fins are located between
adjacent tubes of the plurality of tubes. The one or more fins are
spaced by a fin pitch (F.sub.P) and are configured to improve
thermal energy transfer between the plurality of tubes and ambient
air. Each fin includes a fin extension extending beyond a tube
width. The extended portion of the fin is laterally flared and
shaped to reduce capillary effects and enhance water drainage.
[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 DRAWINGS
[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 cross-sectional view of an embodiment of a heat
exchanger;
[0008] FIG. 2 is another cross-sectional view of an embodiment of a
heat exchanger illustrating a fin face, fin cap, fin radius and
louver of the heat exchanger;
[0009] FIG. 3 is a cross-sectional view of an embodiment of a heat
exchanger illustrating a fin extension;
[0010] FIG. 4 is a cross-sectional view of an embodiment of a heat
exchanger including multiple heat exchanger tubes;
[0011] FIG. 5 is a cross-sectional view of an embodiment of a heat
exchanger including a fin notch;
[0012] FIG. 6 is a perspective view of an embodiment of a heat
exchanger including a fin notch;
[0013] FIG. 7 is a perspective view of an embodiment of a slotted
heat exchanger tube; and
[0014] FIG. 8 is a cross-sectional view of a welded slotted heat
exchanger tube.
[0015] 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
[0016] Shown in FIG. 1 is an embodiment of a tube and fin
arrangement of a heat exchanger 10. The heat exchanger 10 includes
a plurality of tubes 12. Each tube 12 in the embodiment shown
includes multiple channels 14 through which cooling fluid is
circulated. In the embodiment of FIG. 1, each tube includes sixteen
channels 14, but it is to be appreciated that any number of
channels 14 may be utilized. A plurality of fins 16 extend between
the tubes 12 to aid in increasing heat transfer between the tubes
12 and the surrounding air. In some embodiments, the fins 16 are
secured to the tubes 12 by, for example, brazing, or other suitable
means such as for instance soldering or gluing, and in some
embodiments, the fins 16 may have a fin thickness (F.sub.TH) of
between about 50 and about 100 microns. It is to be appreciated
that the fin thickness is merely exemplary, and other fin
thicknesses outside of the described range may be utilized within
the scope of the present disclosure. The heat exchanger 10 of FIG.
1 is typically a horizontal tube heat exchanger of the type used
in, for example, air conditioning condenser applications. It is to
be appreciated that other tube orientations are feasible and within
the scope of the invention.
[0017] Referring now to FIG. 2, the fins 16 are arranged along the
tubes 12 and spaced from each other at a fin pitch (F.sub.P) 18.
The fins 16 of some embodiments are folded or corrugated fins 16.
The fin 16 includes a fin face 20 extending between the tubes 12 at
a fin angle 74 which, in some embodiments, is nonperpendicular to
the tubes 12, and a fin cap 22 disposed at each end of the fin face
20 at the tubes 12 and extending along the tubes 12. The fin 16 is
secured to the tubes 12 at the fin cap 22. The fin cap 22 is
substantially planar, and in some embodiments, the fin face 20 is
also substantially planar.
[0018] Each fin face 20 includes a plurality of through openings,
for example, louvers 24 arrayed along a lateral extent of the fin
16. The louvers 24 improve heat transfer and also assist in
reducing water retention in the heat exchanger by providing an
alternate passage for moisture, water, and/or condensate to drain
through the heat exchanger 10. A transition between each fin cap 22
and fin face 20 is a fin radius (R.sub.C) 26. It is desired to
reduce the fin radius 26 in order for a louver height (L.sub.H) 28
to be increased relative to a fin height (F.sub.H) 30, thus
increasing an overall size of the louver 24 opening within the fin
16. In some embodiments, a ratio of louver height 28 to fin height
30, L.sub.H/F.sub.H, is between about 0.8 and about 0.95, and the
preferred range is between about 0.85 and about 0.92. Further, the
fin radius 26 relates to fin pitch 18 such that a ratio of fin
radius 26 to fin pitch 18, R.sub.C/F.sub.P, is between about 0.1
and about 0.4. The preferred range of R.sub.C/F.sub.P is between
about 0.2 and about 0.3
[0019] Referring now to FIG. 3, in some embodiments, a fin width
(F.sub.W) 32 extends beyond a tube width 34 by an extension 36 at
at least one tube side 38, and in some embodiments, both tube sides
38. In some embodiments, the extension 36 extends laterally away
from the tube side 38 as well as transversely at least partially
across a tube thickness 40. The resulting extension 36 extends
upwardly or downwardly in a horizontal tube 12 heat exchanger 10,
and may be substantially linear or planar in profile, or in other
embodiments may be substantially arcuate, a combination of linear
and arcuate or other profile. As shown in FIG. 3, the extension 36
may comprise two planar extension portions 74, and further, the
extension 36 may have a substantially squared-off cross-section. It
is to be appreciated, however, that the squared-off cross section
is merely exemplary and other cross-sectional shapes are
contemplated within the scope of the present disclosure. Extending
the extensions 36 upwardly or downwardly reduces surface tension
effects and utilizes gravitational forces to encourage flow of
condensate 42 away from the tubes 12 thereby reducing corrosion of
the tubes 12. To achieve the desired drainage, it is not required
that an extension width (E.sub.W) 44 be overly large relative to
the overall fin width (F.sub.W) 32. In some embodiments, a ratio of
extension width 44 to fin width 32, E.sub.W/F.sub.W, is between
about 0.02 and about 0.1, while the preferred E.sub.W/F.sub.W range
is between about 0.02 and about 0.04, to enhance the desired
drainage effect while minimizing the amount of space utilized by
the fins 16 Likewise, a transverse component (E.sub.T) 48 of the
extension 36 does not need to be overly great appreciable relative
to the tube thickness (T.sub.T) 40 to produce the desired effect. A
ratio of the transverse component 48 to the tube thickness 40,
E.sub.T/T.sub.T, is between about 0.05 and about 0.4, while the
preferred E.sub.T/T.sub.T range is between about 0.05 and about
0.15. It is desired, however, that the transverse component 48 be
relatively large when compared to a fin thickness (F.sub.T) 50
(shown in FIG. 2). For example, in some embodiments, a ratio
between the transverse component 48 and the fin thickness 50,
E.sub.T/F.sub.T, is between about 1 and about 3, while the
preferred E.sub.T/F.sub.T range is between about 1.75 and about
2.5. Further, the transverse component 48 is related to the fin
radius 26, such that a ratio of the transverse component 48 to the
fin radius, E.sub.T/R.sub.C, is between about 0.2 and about 2.
[0020] Referring now to FIG. 4, in some embodiments, each fin 16
spans two or more tubes 12 located at each fin cap 22 with a gap
(T.sub.G) 52 between adjacent tubes 12. As shown in FIGS. 5 and 6,
some embodiments include a fin notch 54 substantially aligned with
the tube gap 52. A relationship exists between a tube pitch
(T.sub.P) 56, which is a distance between tubes 12 located at
opposing fin caps 22 and a notch height (N.sub.H) 58 of the fin
notch 54. A ratio of the notch height 58 to the tube pitch 56,
N.sub.H/(T.sub.P-T.sub.T) is about 0.15 to about 0.3. In some
embodiments, N.sub.H/(T.sub.P-T.sub.T) is about 0.1 to about 0.2 to
encourage moisture flow outward toward the extensions 36. Shown
clearly in FIG. 6, each fin notch 54 has a notch width (N.sub.W) 60
extending in a direction along the length of the tube 12. The notch
width 60 is sized relative to the fin pitch 18, the fin height 30,
and the tube pitch 56 in order to maximize the gravitational
effects and reduction in surface tension desired. The relationship
is expressed as follows:
N.sub.w/(F.sub.P-Sqrt(F.sub.H.sup.2-(T.sub.P-T.sub.T).sup.2)
In some embodiments, the relationship equals about 0.3 to about
0.9, while the preferred range of the relationship is about 0.4 to
about 0.7.
[0021] Another embodiment is illustrated in FIG. 7. The embodiment
of FIG. 7 illustrates a tube 12 including a tube slot 62 extending
therethrough. The tube slot 62 defines an additional egress
location for moisture, condensate, and/or water from the heat
exchanger 10. The slot 62 has a slot width (S.sub.W) 66. A ratio of
the slot width 66 to a tube width (T.sub.W) 68, S.sub.W/T.sub.W, is
between about 0.05 and about 0.2 to provide the moisture egress
while not significantly reducing an amount of fluid the tube 12 is
capable of carrying or effecting heat transfer and pressure drop
characteristics of heat exchanger 10. The slot 62 has a slot length
(S.sub.L) 70 extending along a tube length (T.sub.L) 72 of the tube
12. It is desired for the slot length 70 to be as large as possible
given the tube length 72, to spread its effect over the entire tube
length 72. Thus, a ratio of the slot length 70 to the tube length
72, S.sub.L/T.sub.L, is between about 0.8 and about 0.95. As shown,
the slotted tube 12 may include one or more refrigerant inlets 74
and one or more refrigerant outlets 76, and may be connected to one
or more coolant manifolds 78 at either end of the tube length 72.
The slotted tube 12 may be formed one of many ways including
extrusion of the slotted tube 12. The slot 62 may be formed in a
secondary operation by, for example, punching. Referring to FIG. 8,
the slotted tube 12 may be formed by welding of an inner sheet 80
and an outer sheet 82 to a corrugated sheet 84 which forms dividers
between adjacent coolant passages 86.
[0022] 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.
* * * * *