Canadian Patents Database / Patent 2753385 Summary

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(12) Patent: (11) CA 2753385
(54) English Title: HEAT EXCHANGER
(54) French Title: ECHANGEUR THERMIQUE
(51) International Patent Classification (IPC):
  • F28F 1/10 (2006.01)
  • F28F 1/12 (2006.01)
  • F28F 1/32 (2006.01)
(72) Inventors :
  • HANCOCK, STEPHEN S. (United States of America)
(73) Owners :
  • TRANE INTERNATIONAL INC. (United States of America)
(71) Applicants :
  • TRANE INTERNATIONAL INC. (United States of America)
(74) Agent: FETHERSTONHAUGH & CO.
(74) Associate agent:
(45) Issued: 2015-10-06
(86) PCT Filing Date: 2010-02-23
(87) Open to Public Inspection: 2010-08-26
Examination requested: 2011-08-22
(30) Availability of licence: N/A
(30) Language of filing: English

(30) Application Priority Data:
Application No. Country/Territory Date
12/390,843 United States of America 2009-02-23

English Abstract





A heat exchanger has a first
fin having a hole, a collar attached to the first
fin and associated with the hole, and a bluff
body carried by the first fin. The bluff body is
partially directly upstream of the collar. A
heat exchanger has a fin having a hole, a collar
attached to the fin and associated with the
hole, and a bluff body associated with the fin.
A configuration of the bluff body is associated
with a fin pitch separation distance of the
heat exchanger. A method of increasing a
heat exchange efficiency of a heat exchanger
is provided that includes passing an air flow
adjacent a surface of a fin, obstructing the air
flow with a bluff body, reducing a thickness
of a thermal boundary layer, and locating a
reduced thickness portion of the thermal
boundary layer adjacent to a collar associated
with the fin.




French Abstract

L'invention concerne un échangeur thermique qui présente une première ailette possédant un trou, un collier fixé à la première ailette et associé au trou, et un corps non profilé porté par la première ailette. Ledit corps est partiellement directement en amont du collier. L'invention concerne également un échangeur thermique qui présente une ailette possédant un trou, un collier fixé à l'ailette et associé au trou, et un corps non profilé associé à l'ailette. Une configuration du corps non profilé est associée à une distance de séparation du pas d'ailette de l'échangeur thermique. L'invention concerne également un procédé d'augmentation du rendement de l'échange thermique d'un échangeur thermique, le procédé consistant à faire passer un flux d'air de façon adjacente à une surface d'une ailette, à obstruer le flux d'air avec un corps non profilé, à réduire l'épaisseur d'une couche limite thermique et à disposer une partie à épaisseur réduite de la couche limite thermique de façon adjacente à un collier associé à l'ailette.


Note: Claims are shown in the official language in which they were submitted.




CLAIMS
What is claimed is:
1. A heat exchanger, comprising:
a first fin having a hole;
a collar attached to the first fin and associated with the hole; and
a bluff body carried by the first fin wherein the bluff body is at least
partially directly
upstream of a portion of the collar;
wherein the first fin is a louvered fin and the bluff body is disposed (1) on
a substantially
flat non-louvered region of the first fin that continuously surrounds the
collar and is bordered by
louvers of the first fin on at least two opposing sides and a downstream side
of the substantially
flat non-louvered region and (2) between a louvered region of the first fin
located upstream
relative to the bluff body and the collar, the space between the bluff body
and the louvered region
being free of collars;
wherein the substantially flat non-louvered region is shaped differently from
a shape of
the hole; and
wherein the louvers of the first fin that border the substantially flat non-
louvered region
on the at least two opposing sides and the downstream side form a continuous
louvered boundary
around the substantially flat non-louvered region such that no substantially
flat non-louvered
portion of the first fin other than the substantially flat non-louvered region
is located between the
louvers that border the substantially flat non-louvered region of the first
fin on the at least two
opposing sides and the louvers that border the substantially flat non-louvered
region of the first
fin on the downstream side.
11




2. The heat exchanger according to claim 1, further comprising:
a second fin separated from the first fin by a fin pitch separation distance
and wherein the
bluff body comprises a radius having a value between about 0.5 to about 1.5
times the fin pitch
separation distance.
3. The heat exchanger according to claim 1, further comprising:
a second fin separated from the first fin by a fin pitch separation distance
wherein the
bluff body has a maximum length measured substantially transverse to an
incoming flow of air
and wherein about one-half the maximum length is a value between about 0.5 to
about 1.5 times
the fin pitch separation distance.
4. The heat exchanger according to claim 1, wherein the bluff body is
hemispherical in
shape.
5. The heat exchanger according to claim 4, wherein the bluff body is
formed as an
indentation of the first fin.
6. The heat exchanger according to claim 4, wherein the bluff body is
secured to the first fin.
7. The heat exchanger according to claim 1, further comprising:
a second fin separated from the first fin by a fin pitch separation distance
wherein the
bluff body is located on the first fin and offset from the collar in an
upstream direction by a
distance of about one to about five times a diameter of the bluff body.
12




8. The heat exchanger according to claim 1, further comprising:
a second fin separated from the first fin by a fin pitch separation distance
wherein the
bluff body is located on the first fin and offset from the collar in an
upstream direction by a
distance of about one to about five times a maximum length of the bluff body
wherein the
maximum length is measured substantially transverse to an incoming flow of
air.
9. A heat exchanger, comprising:
a fin having a hole;
a collar attached to the fin and associated with the hole; and
a bluff body associated with the fin wherein a configuration of the bluff body
is
associated with a fin pitch separation distance of the heat exchanger;
wherein the fin is a louvered fin and the bluff body is disposed (1) on a
substantially flat
non-louvered region of the fin that continuously surrounds the collar and is
surrounded by louvers
of the fin on at least two opposing sides and a downstream side of the
substantially flat non-
louvered region and (2) between a louvered region of the fin located upstream
relative to the bluff
body and the collar, the space between the bluff body and the louvered region
being free of
collars;
wherein the substantially flat non-louvered region is shaped differently from
a shape of
the hole; and
wherein the louvers of the fin that border the substantially flat non-louvered
region on the
at least two opposing sides and the downstream side form a continuous louvered
boundary
around the substantially flat non-louvered region such that no substantially
flat non-louvered
13




portion of the fin other than the substantially flat non-louvered region is
located between the
louvers that border the substantially flat non-louvered region of the fin on
the at least two
opposing sides and the louvers that border the substantially flat non-louvered
region of the fin on
the downstream side.
10. The heat exchanger according to claim 9, wherein the bluff body
comprises a radius
having a value between about 0.5 to about 1.5 times the fin pitch separation
distance.
11. The heat exchanger according to claim 9, wherein the bluff body has a
maximum length
measured substantially transverse to an incoming flow of air and wherein about
one-half the
maximum length is a value between about 0.5 to about 1.5 times the fin pitch
separation distance.
12. The heat exchanger according to claim 9, wherein the bluff body is
formed as an
indentation of the fin.
13. The heat exchanger according to claim 9, wherein the bluff body is
located on the fin and
offset from the collar in an upstream direction by a distance of about one to
about five times a
diameter of the bluff body.
14


14. The heat exchanger according to claim 9, wherein the bluff body is
located on the fin and
offset from the collar in an upstream direction by a distance of about one to
about five times a
maximum length of the bluff body wherein the maximum length is measured
substantially
transverse to an incoming flow of air.
15. A method of increasing a heat exchange efficiency of a heat exchanger,
comprising:
passing an air flow adjacent a surface of a fin of the heat exchanger;
at least partially obstructing the air flow with a bluff body associated with
the fin; and
reducing a thickness of a thermal boundary layer downstream of the bluff body;
wherein the fin is a louvered fin and the bluff body is disposed (1) on a
substantially flat
non-louvered region of the fin that continuously surrounds the collar and is
surrounded by louvers
of the fin on at least two opposing sides and a downstream side of the
substantially flat non-
louvered region and (2) between a louvered region of the fin located upstream
relative to the bluff
body and the collar, the space between the bluff body and the louvered region
being free of
collars;
wherein the substantially flat non-louvered region is shaped differently from
a shape of
the hole; and
wherein the louvers of the first fin that border the substantially flat non-
louvered region
on the at least two opposing sides and the downstream side form a continuous
louvered boundary
around the substantially flat non-louvered region such that no substantially
flat non-louvered
portion of the fin other than the substantially flat non-louvered region is
located between the
louvers that border the substantially flat non-louvered region of the fin on
the at least two





opposing sides and the louvers that border the substantially flat non-louvered
region of the fin on
the downstream side.
16. The method of claim 15, wherein the reducing the thickness of the
thermal boundary layer
adjacent the collar comprises providing the bluff body with a dimension that
is about 0.5 to about
1.5 times a fin pitch of the heat exchanger.
17. The method of claim 16, wherein the dimension is a radius of the bluff
body.
18. The method of claim 15, wherein the reducing the thickness of the
thermal boundary layer
adjacent the collar comprises locating the bluff body upstream from the collar
by about one to
about five times a dimension of the bluff body.
19. The method of claim 18, wherein the dimension is a diameter of the
bluff body.
20. The method of claim 17, wherein the bluff body is hemispherical in
shape and has a
radius of about 0.5 to about 1.5 times a fin pitch of the heat exchanger and
wherein the bluff body
is located about 1 to about 5 times a diameter of the bluff body upstream from
the collar.
16

Note: Descriptions are shown in the official language in which they were submitted.

CA 02753385 2013-11-08
HEAT EXCHANGER
BACKGROUND
[0001] Heat exchangers are widely used in residential and commercial
heating, ventilating,
and air conditioning (HVAC) systems and applications. A plate fin heat
exchanger or finned-
tube heat exchanger generally comprises a plurality of thin metal plates or
fins (hereinafter,
referred to as "fins"). The fins have holes that accept tubes therethrough. In
most plate fin heat
exchangers, a large number of fins having multiple holes that are arranged to
accept a generally
serpentine arrangement of tubes that pass through the holes. The fins and
tubes are connected so
that heat conduction between the fins and tubes is possible. The fins
typically have a large
amount of surface area to interact with an incoming fluid flow. This fluid can
be air, water,
brine, refrigerant, or any other suitable heat transfer fluid hereafter
referred to as "air". The large
amount of surface area promotes heat exchange between the fins and the
incoming flow of air.
SUMMARY OF THE DISCLOSURE
[0002] In some embodiments, a heat exchanger is provided. The heat
exchanger comprises
a first fin having a hole, a collar attached to the first fin and associated
with the hole, and a bluff
body carried by the first fin wherein the bluff body is at least partially
directly upstream of a
portion of the collar.
[0003] In other embodiments, another heat exchanger is provided. The heat
exchanger
comprises a fin having a hole, a collar attached to the fin and associated
with the hole, and a
bluff body. The bluff body is associated with the fin and a configuration of
the bluff body is
associated with a fin pitch separation distance of the heat exchanger.
[0004] In still other embodiments, a method of increasing a heat exchange
efficiency of a
heat exchanger is provided. The method comprises passing an air flow adjacent
a surface of a
fin of the heat exchanger, at least partially obstructing the air flow with a
bluff body associated
with the fin, and reducing a thickness of a thermal boundary layer downstream
of the bluff
body.
[004a] In the above embodiments, the fin is a louvered fin and the bluff
body is disposed (1)
on a substantially flat non-louvered region of the fin that continuously
surrounds the collar and
is bordered by louvers of the fin on at least two opposing sides and a
downstream side of the
substantially flat non-louvered region and (2) between a louvered region of
the fin located
1

CA 02753385 2013-11-08
upstream relative to the bluff body and the collar, the space between the
bluff body and the
louvered region being free of collars; wherein the substantially flat non-
louvered region is
shaped differently from a shape of the hole; and wherein the louvers of the
fin that border the
substantially flat non-louvered region on the at least two opposing sides and
the downstream
side form a continuous louvered boundary around the substantially flat non-
louvered region
such that no substantially flat non-louvered portion of the fin other than the
substantially flat
non-louvered region is located between the louvers that border the
substantially flat non-
louvered region of the fin on the at least two opposing sides and the louvers
that border the
substantially flat non-louvered region of the fin on the downstream side.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] For a more complete understanding of this disclosure, reference is
now made to the
following brief description, taken in connection with the accompanying
drawings and detailed
description, wherein like reference numerals represent like parts.
[0006] Figure 1 is an orthogonal top view of a portion of a plate fin heat
exchanger;
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[0007] Figure 2 is an oblique view of a portion of another plate fin heat
exchanger;
[0008] Figure 3 is an orthogonal top view of a portion of still another
plate fin heat exchanger;
[0009] Figure 4 is a an orthogonal side view of a thermal boundary layer
caused by a bluff body
of the plate fin heat exchanger of Figure 3;
[0010] Figure 5 is a flow chart illustrating a method for constructing a
portion of a plate fin heat
exchanger; and
[0011] Figure 6 is a flow chart illustrating a method of increasing a heat
transfer efficiency of a
heat exchanger.
DETAILED DESCRIPTION OF THE EMBODIMENT(S)
[0012] A heat exchange efficiency of a plate fin heat exchanger depends,
among other things, on
the structural features of the components of the plate fin heat exchanger and
the orientation of those
components with respect an incoming flow of air. Referring now to Figure 1, an
orthogonal view of
a section of a fin 102 of an existing plate fin heat exchanger 100 is shown.
The fin 102 comprises a
plurality of turbulence-inducing louvers 112 disposed on a surface of fin 102.
An incoming flow of
air 126 is indicated by dashed arrows. The dashed arrows point generally
leftward in Figure 1,
thereby indicating movement of the incoming flow of air 126 as being generally
from right to left in
Figure 1. The louvers 112 generally surround a non-louvered, generally flat,
substantially oval-
shaped base region 110. A substantially annular collar 108 is secured to the
base region 110 and lies
substantially coaxial with a hole formed in the fin 102. The collar 108 serves
to increase the
mechanical strength of the joinder between the fin and a tube 106 that passes
through the hole and
the collar 108. The collar 108 also serves to increase the heat conductivity
between the tube 106 and
the fin 102. The tube 106 is of the so-called "interactive" tube types and the
tube 106 allows
passage of fluids (i.e. refrigerants) through tube 106 and consequently
generally perpendicularly
through the thickness of the fm 102. The fin 102, tube 106, and collar 108 are
each constructed of a
suitable thermally-conductive material, such as, but not limited to, copper,
aluminum, and the like.
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CA 02753385 2011-08-22
WO 2010/096796 PCT/US2010/024995
[0013]
When the plate fin heat exchanger 100 is used in a cooling mode of operation,
the
incoming flow of air 126 transfers heat to the fluid flowing through the tube
106. When the plate fin
heat exchanger 100 is used in a heating mode of operation, heat is transferred
from the fluid flowing
through the tube 106 to the incoming flow of air 126. Of course, the above-
described transferring of
heat between the incoming flow of air 126 and the fluid flowing through the
tube 106 is
accomplished in part by transferring heat through the fm 102, collar 108,
and/or tube 106 as
intermediate heat conductors between the incoming flow of air 126 and the
fluid flowing through the
tube 106.
[0014]
A thermal region 104 (experimentally identifiable by infrared imaging), the
bounds of
which are represented by a dashed line in Figure 1, delineates an area where a
reduced amount of
thermal mixing occurs due to the temperature difference between the incoming
flow of air 126 and
the components of the plate tin heat exchanger 100. The thermal region 104 is
an area where little
thermal mixing and heat exchange occurs between the incoming flow of air 126
and the components
of the plate fin heat exchanger 100. Such thermal mixing and heat exchange is
generally beneficial
to the operation of the plate fin heat exchanger 100. However, the portion of
the thermal mixing and
heat exchange that occurs downstream of the tube 106 (to the left of the tube
106 in Figure 1) is not
optimal since thermal mixing and heat exchange is preferred in areas having
the highest flow
agitation and temperature gradient, i.e. between the incoming flow of air 126
and the tube 106 (and
generally near the upstream or right side portions of the tube 106 and the
collar 108).
[0015]
The present disclosure provides systems and methods for increasing the heat
exchange
efficiency of heat exchangers by causing thermal mixing and heat transfer near
the interface between
a fin, collar, and tube of the plate fin heat exchanger. The increase in heat
exchange efficiency of
heat exchangers is accomplished, at least in some embodiments, by providing
bluff bodies on fins of
heat exchangers. The bluff bodies, at least in some embodiments, are located
substantially directly
upstream of the tubes of heat exchangers.
[0016]
Referring now to Figure 2, an oblique view of a portion of a plate fin heat
exchanger 200
is shown. For clarity and ease of discussion, only two fins 202 of the plate
fin heat exchanger 200
are shown and the fins 202 are arranged in a so-called "open stack"
configuration. However, it
should be understood that plate fin heat exchanger 200 comprises more than two
fins 202. Further,
it will be appreciated that the teachings disclosed herein are also applicable
to any other type of heat
exchanger that has a fin associated with a tube. Still further, alternative
embodiments of plate fin
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WO 2010/096796 PCT/US2010/024995
heat exchangers and other types of heat exchangers may comprise any number of
fins, even as few
as one fin.
[0017] Referring now to Figure 2, plate fin heat exchanger 200 comprises
fins 202. Each fin
202 comprises an annular collar 208 attached thereto in substantially the same
manner collar 108 is
attached to fin 102. Tubes 206, which are substantially similar to tube 106,
are disposed through
collars 208 and fins 202 in substantially the same manner tube 106 is disposed
through collar 108
and fin 102. However, unlike plate fin heat exchanger 100, plate fin heat
exchanger 200 comprises a
plurality of bluff bodies 216.
[0018] The bluff bodies 216 are associated with the surfaces 204 of fins
202. A dominant
aerodynamic drag characteristic of bluff bodies 216 is pressure drag (e.g., as
opposed to frictional or
viscous drag associated with a "streamlined" body). In this embodiment, bluff
bodies 216 are
located generally directly upstream of respective fin collars 208 so that
associated bluff bodies 216
and collars 208 substantially lie along shared bisection lines 210. Bisection
lines 210 (only two
shown in Figure 2 for clarity) lie generally parallel with the direction of an
incoming air flow 226.
Of course, in other embodiments, bluff bodies may be generally upstream of the
collars without
lying on the bisection lines 210. For example, bluff bodies may altematively
be located upstream of
the collars and/or tubes while still at least partially remaining within an
upstream footprint of the
associated collars and/or tubes generally defined by the width and/or diameter
of the collars and/or
tubes. When at least some of a bluff body is within an upstream footprint of
the associated collars
and/or tubes, the bluff body is referred to as being at least partially
directly upstream of a portion of
the collars and/or tubes.
[0019] In this embodiment, bluff bodies 216 are formed as indentations in
fins 202 and protrude
away from surfaces 204. The bluff bodies 216 are generally hemispherical in
shape and may be
referred to alternatively as "dimples" or "bumps". In alternative embodiments,
a bluff body may
comprise any other suitable shape and may be deposited onto surfaces such as
surfaces 204 rather
than being integral and formed from such surfaces. In either case, whether a
bluff body is formed as
a piece of a fin or whether a bluff body is attached to a fin, the bluff body
is referred to as being
carried by the fin. Bluff bodies 216 and other embodiments of bluff bodies may
be formed by
pressing, milling, machining, molding, or any other suitable manufacturing
technique. As described
in greater detail below, alternative embodiments of bluff bodies may be
generally spherical,
cylindrical, elliptical, rectangular, triangular, or any other suitable shape.
It will be appreciated that
in embodiments where the shape of the bluff body is not easily defined by a
radius as is possible
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with hemispheres and cylinders, a substitute dimension may be selected for
determining the size and
location of the bluff body. For example, the substitute dimension may be
selected as one-half the
length of the bluff body, where the length is the maximum length of the bluff
body as measured
transverse to the incoming flow of air.
[0020] In this embodiment, a suitable radius 214 (only one shown in Figure
2 for clarity), for a
hemispherical bluff body 216 is in a range of between about 0.5 to about 1.5
times a fin pitch 212
where the fin pitch 212 is defined as a distance between adjacent fins 202.
For example, in an
embodiment where a fin pitch has a value of about 1 inch, a radius may have a
value of between
about 1/2 inch to about 1 1/2 inches. In some embodiments, the radius of a
bluff body may be about
1/20th to 3/20ths of an inch. Further, a suitable separation distance 224
between the bluff bodies 216
and the associated collars 208 is in a range of between about 1 to about 5
times the diameter of bluff
body 216 (i.e. about 2 to about 10 times the radii 214 of bluff bodies 216).
For example, in an
embodiment where a fin pitch has a value of about 1 inch and a radius of the
bluff body has a value
of about 1 inch, the bluff body may be located between about 2 inches to about
10 inches upstream
from the associated collar. In this embodiment, the separation distance is
generally measured along
bisection lines 210 between the collars 208 and the associated bluff bodies
216. In some
embodiments, a bluff body may be located on a fin and separated from an
associated collar and/or
tube by a distance of about 0.1 to about 0.25 inches in an upstream direction.
In some embodiments,
the fin pitch may be a design parameter determined by the diameters of the
tubes. In some
embodiments, the diameter of tubes may be in a range of about 1/8 inch to
about 1 inch. In an
embodiment where the diameter of a tube is about 3/8 inch, the corresponding
appropriate fin pitch
may be in a range of about 0.05 inches to about 0.25 inches. It will be
appreciated that the size and
location of a bluff body 216 are parameters of the configuration of the bluff
body 216. In some
embodiments including the plate fin heat exchanger 200, the configuration of a
bluff body (i.e. a
dimension of the bluff body and the location of the bluff body relative to
either the tube andJor the
collar) is associated with and/or depends on the fin pitch of the heat
exchanger.
[0021j Referring now to Figure 3, an orthogonal view of a section of a fin
302 of a plate fin heat
exchanger 300 is shown. Plate fin heat exchanger 300 is substantially similar
to plate fin heat
exchanger 100, except that plate fin heat exchanger 300 comprises a bluff body
316 as described in
more detail below. The fin 302 comprises a plurality of turbulence-inducing
louvers 312 disposed
on a surface of fin 302. However, it will be appreciated that alternative
embodiments of heat
exchangers may include no turbulence-inducing louvers. An incoming flow of air
326 is indicated

CA 02753385 2011-08-22
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by dashed arrows. The dashed arrows point generally leftward in Figure 3,
thereby indicating
movement of the incoming flow of air 326 as being generally from right to left
in Figure 3. The
louvers 312 generally surround a non-louvered, generally flat, substantially
oval-shaped base region
310. A substantially annular collar 308 is secured to the base region 310 and
lies substantially
coaxial with a hole fanned in the fin 302. The collar 308 serves to increase
the mechanical strength
of the joinder between the fin 302 and a tube 302 that passes through the hole
and the collar 308.
The collar 308 also serves to increase the heat conductivity between the tube
306 and the fin 308.
The tube 306 is of the so-called "interactive" tube types and the tube 306
allows passage of fluids
(i.e. refrigerants) through tube 306 and consequently generally
perpendicularly through the thickness
of the fin 306. The fin 306, tube 306, and collar 308 are each constructed of
a suitable thetinally-
conductive material, such as, but not limited to, copper, aluminum, and the
like.
[0022] When the plate fin heat exchanger 300 is used in a cooling mode of
operation, the
incoming flow of air 326 transfers heat to the fluid flowing through the tube
306. When the plate fin
heat exchanger 300 is used in a heating mode of operation, heat is transferred
from the fluid flowing
through the tube 306 to the incoming flow of air 326. Of course, the above-
described transferring of
heat between the incoming flow of air 326 and the fluid flowing through the
tube 306 is
accomplished in part by transferring heat through the fin 302, collar 308,
and/or tube 306 as
intermediate heat conductors between the incoming flow of air 326 and the
fluid flowing through the
tube 306.
[0023] The plate fin heat exchanger 300 further comprises a bluff body 316
substantially similar
to bluff body 216. The bluff body 316 lies generally directly upstream of
collar 308 and protrudes
up and away from surface 310. Bluff body 316 is a hemispherical bump with a
radius 317. In some
embodiments, the radius 317 may be in a range of about 1/20th to about 3/20ths
of an inch. The bluff
body 316 interferes with and agitates the flow of incoming air 326 diminishing
a thermal region 304
that has been experimentally identified through the use of infrared imaging.
The thermal region 304,
the bounds of which are represented by a dashed line in Figure 3, delineates
an area where a reduced
amount of thermal mixing occurs due to the temperature difference between the
incoming flow of air
326 and the components of the plate fin heat exchanger 300. The thermal region
304 is an area
where little thermal mixing and heat exchange occurs between the incoming flow
of air 326 and the
components of the plate fin heat exchanger 300. Such thethial mixing and heat
exchange is
generally beneficial to the operation of the plate fin heat exchanger 300.
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[0024] The incoming flow of air 326 flows over and around bluff body 316,
improving thermal
mixing primarily upstream of and around the outer surfaces of the tube 306 and
the collar 308. By
improving the thermal mixing in this marmer and reducing the region of poor
heat transfer
represented by region 304 as opposed to the manner and location of region 104,
a heat exchange
efficiency of the plate fin heat exchanger 300 is improved.
[0025] In the embodiments comprising the bluff bodies 216 and 316, the
bluff bodies 216 and
316 create a stream-wise vortex in the incoming flows of air 226 and 326 that
facilitates the transfer
of heat. In particular, for example, bluff body 316 generates two stream-wise
vortices in the
incoming flow of air 326. Alternatively, the two vortices may be considered
two legs of a single
vortex that wraps around the upstream-facing surface of bluff body 316. Due to
the vortex shape,
the vortex may be referred to as a "horseshoe vortex" or a "hairpin vortex".
Figure 4 is an
orthogonal side view of a thermal image of the effect the horseshoe vortex
generated by bluff body
316 has on a thermal boundary layer, and the effect of this vortex on a
thermal boundary layer 307
are depicted in Figure 4. Generally the thermal boundary layer 307 signifies
an area over which a
temperature gradient exists between the fin 302 and the incoming flow of air
326. Figure 4 shows
that thermal boundary layer 307 is thickest upstream from the bluff body 316
at upstream portion
307a of the thermal boundary layer 307. Figure 4 further shows that the
thermal boundary layer 307
is removed from the surface of fin 302 immediately downstream of bluff body
216 at offset portion
307b of the thermal boundary layer 307.
[0026] Still further, a thin reformation portion 307c forms adjacent the
surface of fin 302 while
some offset remnant portions 307d exist offset from fm 302 but disconnected
from and downstream
from offset portion 307b. Finally, it is shown that the thermal boundary layer
307 gradually
increases in thickness between thin reformation portion 307c and the further
downstream reduced
thickness portion 307e. It will be appreciated that the bluff body 316 causes
the thinning of the
boundary layer 307 which indicates that heat transfer is accomplished more
efficiently downstream
of the bluff body 316 than upstream of the bluff body 316 at upstream portion
307a. By thinning
the thermal boundary layer 307 in this manner and by causing the thinned
thermal boundary layer
307 to exist substantially adjacent the collar 308 and the tube 306, the plate
fin heat exchanger 300
exchanges heat more efficiently. Further, the vortex agitates the viscous
boundary layer around the
tube 306 thereby reducing a pressure drop that may occur near the tube 306.
Empirical data
indicates that, in some embodiments, the heat transfer efficiency of the fin
302 may be substantially
7

CA 02753385 2011-08-22
WO 2010/096796 PCT/US2010/024995
higher by including the bluff body 316 as shown in Figures 3 and 4.
[0027] In some embodiments, a plate fin substantially similar to fin 302
may be used in heat
exchangers for HVAC residential applications such as for example, heating
and/or air conditioning
systems in apartments, condominiums, dwellings, or houses. In other
embodiments, a plate fin
substantially similar to fin 302 may be used in heat exchangers for HVAC
commercial applications
such as, for example, HVAC systems in commercial, public or industrial
buildings or facilities, or
other types of buildings or facilities that distribute conditioned air. Also,
in some embodiments, a
plate fin substantially similar to fin 302 may be incorporated into various
components and structures
that might benefit from the use of a fin with a bluff body disposed thereon,
such as for example, an
evaporative coil of an outdoor air coil or a condenser coil in an air handling
unit. In any event, it
should be understood that the embodiments depicted in Figures 1-4 are
described herein for
illustrative purposes and are not intended to be limited to any particular
heat exchanger, HVAC, or
air handling application, type of dwelling, building or facility, or other
structural or functional
environment.
[0028] Figure 5 details the steps of a method 400 of constructing a HVAC
heat exchanger in
accordance with the principles disclosed herein. For example, method 400 may
be used to construct
one or more of the fins 202, 302.
[0029] At step 402, a plate fin is formed. For example, the plate fin may
be structurally and
functionally similar to that of the fins 202, 302. The fin may include a thin
elongated plate
constructed of a thermally conductive material such as copper or aluminum.
[0030] At step 404, a hole is formed through the fin. For example, the
formed hole may be
structurally and functionally similar to that of the opening provided by the
holes associated with
collars 108, 208, 308. The hole is sized to accommodate a tube such as 106,
206, 306 and might be
formed by a mechanical punch or mill.
[0031] At step 406, a collar is assembled in association with the hole and
the fin. For example,
the collar may be structurally and functionally similar to the collar 108,
208, 308. In some
embodiments, the collar may include a thermally conductive material and might
be mounted over
the associated hole, and fixed to the fin by welding or brazing. In other
embodiments, the collar
may be molded or pressed into the fin.
[0032] At step 408, a bluff body is formed adjacent to the collar on the
fin. For example, the
formed bluff body may be structurally and functionally similar to that of the
bluff bodies 216, 316.
The bluff body might be a hemi-spherical bump, or might include other shapes.
In some
8

CA 02753385 2011-08-22
WO 2010/096796 PCT/US2010/024995
embodiments, the bluff body may be formed by, for example pressing, stamping,
milling, or
molding the bluff body into the fin. In other embodiments, the bluff body
might be disposed on the
fin rather than formed from the fin. The size and location of the bluff body
may be any of those
locations and sized described above with respect to bluff bodies 216, 316.
Note, it is to be
understood that the steps 402, 404, 406, and 408 may be interchanged and may
occur sequentially or
in parallel. For example, the collar might be formed over the fin prior to
forming the hole through at
steps 406 and 404. Alternatively, the bluff body and the collar may be formed
prior to forming the
hole at steps 408, 406, and 404. This disposing the bluff body on radiative
bodies, on a fin in this
embodiment, at the above-described locations with above-described dimensions
promotes enhanced
heat transfer efficiency and greater thermal mixing.
[0033] Referring now to Figure 6, a method 500 of increasing a heat
exchange efficiency of a
heat exchanger is shown. The method 500 is accomplished, at block 502, by
passing an incoming
flow of air (such as incoming flow of air 126, 226, 326) over a surface of a
fin such as fin 102, 202,
302. Next, at block 504, the incoming flow of air is at least partially
obstructed by a bluff body
(such as bluff body 216, 316) that is associated with the fin. Next at block
506, due to the
obstruction caused by the bluff body, a thickness of a thermal boundary layer
is reduced downstream
of the bluff body. Finally at block 508, the thermal boundary layer is caused
to be located adjacent a
collar associated with the fin. It will be appreciated that the sizing and
location of the bluff body on
the fin contributes to the location of the reduced thickness boundary layer
adjacent the collar. It will
further be appreciated that in alternative embodiments where no collar is
used, the reduced thickness
boundary layer may be caused to be located adjacent a tube associated with the
fin. In the manner
described above, a heat exchange efficiency of a heat exchanger may be
increased.
[0034] At least one embodiment is disclosed and variations, combinations,
and/or modifications
of the embodiment(s) and/or features of the embodiment(s) made by a person
having ordinary skill
in the art are within the scope of the disclosure. Alternative embodiments
that result from
combining, integrating, and/or omitting features of the embodiment(s) are also
within the scope of
the disclosure. Where numerical ranges or limitations are expressly stated,
such express ranges or
limitations should be understood to include iterative ranges or limitations of
like magnitude falling
within the expressly stated ranges or limitations (e.g., from about 1 to about
10 includes, 2, 3, 4, etc.;
greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a
numerical range with a
lower limit, R1, and an upper limit, Ru, is disclosed, any number falling
within the range is
specifically disclosed. In particular, the following numbers within the range
are specifically
9

CA 02753385 2013-11-08
disclosed: R=Ri+k*(Ru-Ri), wherein k is a variable ranging from 1 percent to
100 percent with
a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent,
5 percent, ... 50
percent, 51 percent, 52 percent, ..., 95 percent, 96 percent, 97 percent, 98
percent, 99 percent, or
100 percent. Moreover, any numerical range defined by two R numbers as defined
in the above
is also specifically disclosed. Use of the term "optionally" with respect to
any element of a
claim means that the element is required, or alternatively, the element is not
required, both
alternatives being within the scope of the claim. Use of broader terms such as
comprises,
includes, and having should be understood to provide support for narrower
terms such as
consisting of, consisting essentially of, and comprised substantially of
Accordingly, the scope
of protection is not limited by the description set out above but is defined
by the claims that
follow, that scope including all equivalents of the subject matter of the
claims. Each and every
claim is incorporated as further disclosure into the specification and the
claims are
embodiment(s) of the present invention. The discussion of a reference in the
disclosure is not
an admission that it is prior art, especially any reference that has a
publication date after the
priority date of this application.

A single figure which represents the drawing illustrating the invention.

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Admin Status

Title Date
Forecasted Issue Date 2015-10-06
(86) PCT Filing Date 2010-02-23
(87) PCT Publication Date 2010-08-26
(85) National Entry 2011-08-22
Examination Requested 2011-08-22
(45) Issued 2015-10-06
Lapsed 2017-02-23

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $800.00 2011-08-22
Registration of Documents $100.00 2011-08-22
Filing $400.00 2011-08-22
Maintenance Fee - Application - New Act 2 2012-02-23 $100.00 2012-01-31
Maintenance Fee - Application - New Act 3 2013-02-25 $100.00 2013-01-29
Maintenance Fee - Application - New Act 4 2014-02-24 $100.00 2014-01-27
Maintenance Fee - Application - New Act 5 2015-02-23 $200.00 2015-01-22
Final Fee $300.00 2015-06-05
Current owners on record shown in alphabetical order.
Current Owners on Record
TRANE INTERNATIONAL INC.
Past owners on record shown in alphabetical order.
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

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Description
Date
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Abstract 2011-08-22 2 77
Claims 2011-08-22 3 113
Drawings 2011-08-22 6 81
Description 2011-08-22 10 630
Representative Drawing 2011-10-13 1 11
Cover Page 2011-10-18 2 48
Description 2013-11-08 11 645
Claims 2013-11-08 5 184
Claims 2014-08-19 6 186
Representative Drawing 2015-09-11 1 12
Cover Page 2015-09-11 2 50
PCT 2011-08-22 7 262
Assignment 2011-08-22 4 123
Prosecution-Amendment 2013-05-15 2 48
Prosecution-Amendment 2013-11-08 11 459
Prosecution-Amendment 2014-02-20 1 35
Prosecution-Amendment 2014-08-19 8 283
Prosecution-Amendment 2014-08-19 2 87
Correspondence 2015-10-01 2 62
Correspondence 2015-06-05 2 74