U.S. patent application number 09/904788 was filed with the patent office on 2001-11-15 for heat exchanger having selectively compliant end sheet.
This patent application is currently assigned to Ingersoll-Rand Energy Systems Corporation. Invention is credited to Nash, James S..
Application Number | 20010040023 09/904788 |
Document ID | / |
Family ID | 25419780 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040023 |
Kind Code |
A1 |
Nash, James S. |
November 15, 2001 |
Heat exchanger having selectively compliant end sheet
Abstract
A heat exchanger includes a core adapted to heat air with
counter-flowing hot gases. Substantially isothermal hot and cool
portions of the core are interconnected by a matrix portion exposed
to a temperature gradient. A top sheet is positioned over the core
and includes first and second ends and a middle portion between the
first and second ends. The middle portion includes a window and
compliant ligament portions extending alongside the window and
interconnecting the first and second ends. The first and second
ends of the top sheet are positioned over the isothermal cool and
hot portions of the core, respectively, and the middle portion of
the top sheet is positioned over the matrix portion of the core.
The compliant ligament portions of the top sheet are deflectable in
response to the temperature gradient across the matrix portion of
the core to reduce strain on and deflection of the first and second
ends of the top sheet.
Inventors: |
Nash, James S.; (West
Newbury, MA) |
Correspondence
Address: |
MICHAEL BEST & FRIEDRICH LLP
3773 CORPORATE PARKWAY
SUITE 360
CENTER VALLEY
PA
18034-8217
US
|
Assignee: |
Ingersoll-Rand Energy Systems
Corporation
Portsmouth
NH
|
Family ID: |
25419780 |
Appl. No.: |
09/904788 |
Filed: |
July 13, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60010998 |
Feb 1, 1996 |
|
|
|
Current U.S.
Class: |
165/82 ;
165/153 |
Current CPC
Class: |
F28F 3/025 20130101;
F28F 2265/26 20130101; F28D 1/0333 20130101; F28D 9/0043 20130101;
F28F 3/02 20130101; F28F 9/0268 20130101; F28D 21/0003
20130101 |
Class at
Publication: |
165/82 ;
165/153 |
International
Class: |
F28F 007/00; F28D
001/02 |
Claims
1. A heat exchanger comprising: a core including a stacked array of
plate-fin cells, said core being adapted to heat air flowing
through said cells with hot gases flowing in-between said cells;
and a top sheet positioned over said core and including first and
second ends and a middle portion between said first and second
ends, said middle portion including a window and compliant ligament
portions extending alongside said window and interconnecting said
first and second ends; wherein said core includes a substantially
isothermal cool portion into which the flow of air enters said
cells and out of which the flow of hot gases exits said core
in-between said cells, a substantially isothermal hot portion into
which the flow of hot gases enters said core in-between said cells
and out of which the flow of air exits said cells, and a matrix
portion in-between said substantially isothermal hot and cool
portions; wherein the air and hot gases flow in counterflow
relationship to each other through said matrix portion with the air
flowing through said cells and the hot gases flowing in-between
said cells, the majority of heat transfer between the flows of air
and hot gases occurring within said matrix portion to establish a
temperature gradient across said matrix portion; wherein said first
and second ends of said top sheet are positioned over said
isothermal cool and hot portions of said core, respectively, and
said middle portion of said top sheet is positioned over said
matrix portion of said core; and wherein said compliant ligament
portions of said top sheet are deflectable in response to said
temperature gradient across said matrix portion of said core to
reduce strain on and deflection of said first and second ends of
said top sheet.
2. The heat exchanger of claim 1, further comprising a matrix cover
positioned within said window.
3. The heat exchanger of claim 2, wherein a kerf is defined between
said matrix cover and said top sheet.
4. The heat exchanger of claim 3, further comprising a top frame
plate positioned over said top sheet such that said top sheet is
sandwiched between said top frame plate and said core to resist
fluid flow through said kerf.
5. The heat exchanger of claim 3, wherein said kerf surrounds the
entire perimeter of said matrix cover except for at least one
bridge of material joining said matrix cover with at least one of
said ligament portions.
6. The heat exchanger of claim 2, wherein said matrix cover
includes a portion of said top sheet cut from and completely
removable from said middle portion of said top sheet.
7. The heat exchanger of claim 1, wherein each cell includes an
external finned member affixed to an outer surface of said cell,
wherein said top sheet is positioned over the external finned
member of the top cell of said core to define a hot fluid flow
region therebetween to accommodate the flow of hot gases, and
wherein said window is positioned over said external finned
member.
8. The heat exchanger of claim 7, wherein said external finned
member is larger than said window in at least one dimension to
prevent said external finned member from extending through said
window.
Description
[0001] Attention is directed to related U.S. patent application
Ser. No. 09/790,464 filed Feb. 22, 2001, which is a
continuation-in-part of U.S. patent application Ser. No. 09/668,358
filed Sep. 25, 2000, which is a continuation-in-part of U.S.
application Ser. No. 09/409,641 filed Oct. 1, 1999, which is a
continuation of U.S. application Ser. No. 09/239,647 filed Jan, 29,
1999 now U.S. Pat. No. 5,983,992, which is a continuation of U.S.
application Ser. No. 08/792,261 filed Jan. 13, 1997, which claims
the benefit of U.S. Provisional Application No. 60/010,998 filed
Feb. 1, 1996.
BACKGROUND
[0002] The invention relates to recuperators primarily for use in
gas turbine engines, and more particularly to an end sheet
construction for the cores of such recuperators.
SUMMARY
[0003] The present invention provides a heat exchanger comprising a
core including a stacked array of plate-fin cells and a top sheet
positioned over the core.
[0004] The core is adapted to heat air flowing through the cells
with hot gases flowing in-between the cells, and includes a
substantially isothermal cool portion into which the flow of air
enters the cells and out of which the flow of hot gases exits the
core from in-between the cells, a substantially isothermal hot
portion into which the flow of hot gases enters the core in-between
the cells and out of which the flow of air exits the cells, and a
matrix portion in-between the substantially isothermal hot and cool
portions.
[0005] The air and hot gases flow in counterflow relationship to
each other through the matrix portion. The majority of heat
transfer between the flows of air and hot gases occurs within the
matrix portion, and a temperature gradient is therefore established
across the matrix portion.
[0006] The top sheet includes first and second ends and a middle
portion between the first and second ends. The middle portion
includes a window and compliant ligament portions extending
alongside the window and interconnecting the first and second ends.
The first and second ends of the top sheet are positioned over the
isothermal cool and hot portions of the core, respectively, and the
middle portion of the top sheet is positioned over the matrix
portion of the core. The compliant ligament portions of the top
sheet are deflectable in response to the temperature gradient
across the matrix portion of the core to reduce strain on and
deflection of the first and second ends of the top sheet.
[0007] Other features and advantages of the invention will become
apparent to those skilled in the art upon review of the following
detailed description, claims, and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of the core of a
recuperator.
[0009] FIG. 2 is an exploded view of the top cell and end sheet of
the core illustrated in FIG. 1.
[0010] FIG. 3 is a cross-sectional side view of the core of FIG.
1.
[0011] FIG. 4 is an enlarged view of the portion of FIG. 3
encircled by line 4-4.
[0012] FIG. 5 is a plan view of the top sheet of the core
illustrated in FIG. 1.
[0013] FIG. 6 is a plan view of an alternative construction of the
top sheet of the core illustrated in FIG. 1.
[0014] Before one embodiment of the invention is explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangements
of the components set forth in the following description or
illustrated in the drawings. The invention is capable of other
embodiments and of being practiced or being carried out in various
ways. Also, it is understood that the phraseology and terminology
used herein is for the purpose of description and should not be
regarded as limiting. The use of "including" and "comprising" and
variations thereof herein is meant to encompass the items listed
thereafter and equivalents thereof as well as additional items. The
use of "consisting of" and variations thereof herein is meant to
encompass only the items listed thereafter. The use of letters to
identify elements of a method or process is simply for
identification and is not meant to indicate that the elements
should be performed in a particular order.
DETAILED DESCRIPTION
[0015] Plate fin heat exchangers used in microturbine combustors
are discussed in U.S. patent application Ser. Nos. 09/790,464 filed
Feb. 22, 2001, 09/668,358 filed Sep. 25, 2000, 09/409,641 filed
Oct. 1, 1999, 09/239,647 filed Jan. 29, 1999 (now U.S. Pat. No.
5,983,992), and 08/792,261 filed Jan. 13, 1997, and U.S.
Provisional Patent Application No. 60/010,998 filed Feb. 1, 1996,
all assigned to the assignee of the present invention. The entire
contents of each of these patent applications are incorporated
herein by reference.
[0016] FIG. 1 illustrates a core 10 for a recuperator used in a
microturbine. The core 10 includes a plurality of stacked plate-fin
cells 14 defining an inlet manifold 18 and an outlet manifold 22.
As seen in FIG. 2, each cell 14 includes top and bottom plates or
sheets 24, 28, an internal or matrix finned member 32, inlet and
outlet header finned members 34, 36 respectively, and external
finned members 40. The top and bottom plates 24, 28 define manifold
openings 42 that align to define the manifolds 18, 22. The manifold
openings 42 are circular and the manifolds 18, 22 are cylindrical
in the illustrated embodiment, but could have other
configurations.
[0017] Products of combustion or hot gases from the microturbine's
combustor pass through the external finned members 40 between the
cells 14 as illustrated at 44 in FIG. 1. At the same time,
compressed air flows into the inlet manifold 18 as shown at 48,
From the inlet manifold 18, the compressed air enters the cells 14
over the inlet header finned members 34 in the direction indicated
at 49 in FIG. 2. The compressed air then turns about 90.degree. and
flows in the direction indicated at 50 in FIG. 2 as it passes over
the matrix finned members 32. The direction 50 is substantially
opposite the direction 44. Then the compressed air turns about
90.degree. again and flows out of the cells 14 over the outlet
header finned members 36 in the direction 51 in FIG. 2. Finally,
the compressed air flows out of the core through the outlet
manifold 22 as shown at 52 in FIG. 1.
[0018] As seen in FIG. 1, due to the counterflow of the hot
products of combustion over the external finned members 40 and the
compressed air over the matrix finned members 32, the core 10 is
characterized by a substantially isothermal and relatively cool
portion C around the inlet manifold 18 and above and below the
inlet header finned members 34. The flow of air enters the core 10
and the spent products of combustion exit the core 10 through the
substantially isothermal cool portion C. The core 10 is also
characterized by a substantially isothermal and relatively hot
portion H around the outlet manifold 22 and above and below the
outlet header finned members 36. The hot products of combustion
enter the core 10 and the heated flow of air exits the core 10
through the substantially isothermal hot portion H. A matrix
portion M (defined generally between the broken lines 54a and 54b
in FIG. 1) of the core 10, is disposed between the hot and cool
portions H, C of the core 10 and above and below the external
finned members 40 and matrix finned members 32. Most of the heat
transfer between the air and products of combustion takes place in
the matrix portion M of the core 10.
[0019] A hot fluid flow region is defined between the cells 14 and
along the external finned members 40, and a cool fluid flow region
is defined within the cells 14 and along the matrix finned members
32. As described above, hot products of combustion and relatively
cool compressed air flow in opposite directions 44, 50 in the
respective hot and cool fluid flow regions, heat transfer occurs in
the matrix portion M of the core 10, and a temperature gradient is
therefore established across the matrix portion M.
[0020] As seen in FIGS. 1-4, an end sheet or top sheet 56 is
provided on top of the core 10. The uppermost hot fluid flow region
is defined between the top sheet 56 and the cell 14 at the top of
the core 10. The top sheet 56 includes first and second ends 57,
58, positioned over the substantially isothermal cool and hot
portions C, H, respectively, and a middle portion 59 disposed
between the first and second ends 57, 58. A window 60 (FIG. 2) is
cut into the middle portion 59 of the top sheet 56. A matrix cover
64, which is preferably the portion of the top sheet 56 cut out
when the window 60 is created, is positioned within the window 60.
Compliant strips or ligament portions 66 therefore run alongside
the window 60 and interconnect the first and second ends 57, 58 of
the top sheet 56. The window 60 is positioned directly over the top
external finned member 40. The window 60 is slightly smaller in at
least one dimension (e.g., length and/or width) than the external
finned member 40 so that the external finned member 40 does not
extend through the window 60.
[0021] As seen in FIGS. 1 and 3-5, a kerf 68 is created during
formation of the window 60 and surrounds the matrix cover 64. The
window 60 is preferably created with a laser cutting process, and
the kerf 68 is therefore preferably about 0.03 inches wide. The
kerf 68 illustrated in the drawings is greatly exaggerated for the
purposes of illustration and is not drawn to scale.
[0022] A top frame plate 72 is positioned over the top sheet 56 and
covers the kerf 68 to minimize leakage of products of combustion
through the kerf 68. The top frame plate 72 is preferably fixed to
a frame surrounding the core 10 such that the top frame plate 72
restricts vertical expansion of the core 10 during thermal cycles.
Alternatively, the top frame plate 72 may be resiliently biased
down onto the top sheet 56 by springs or other biasing members such
that vertical thermal expansion of the core 10 is permitted while
the top frame plate 72 is held firmly against the top sheet 56.
[0023] In another embodiment, illustrated in FIG. 6, the kerf 68
may not completely surround the matrix cover 64. In such an
embodiment, bridges of material 76 are left intact between the
matrix cover 64 and the top sheet 56. This embodiment may improve
handling of the top sheet 56 and matrix cover 64 because they are
interconnected and may be handled together. Additionally, this
embodiment ensures that the matrix cover 64 is centered in the
window 60. Also, once the heat exchanger is set up, it should not
be a problem if the bridges 76 crack or break during thermal cycles
because the matrix cover 64 is sandwiched between the top frame
plate 72 and the top cell 14 of the core 10.
[0024] In operation, the hot and cool portions H, C of the core 10
are subject to a substantially isothermal load, and the matrix
portion M is exposed to the temperature gradient. Because the first
and second ends 57, 58 of the top sheet 56 are connected only by
the ligament portions 66, the middle portion 59 of the top sheet 56
is better able to accommodate the temperature gradient and the
strain on and deflection of the first and second ends 57, 58 are
reduced. The ligament portions 66 may therefore be referred to as
compliant portions of the top sheet 56.
[0025] It should be noted that the ligament portions 66 are not
necessarily drawn to scale in the drawings. It is preferably that
the ligament portions 66 are longer (i. e., in the direction
extending between the ends 57, 58) than wide to enhance their
compliant nature. In practice the ligament portions 66 may be made
longer and narrower than illustrated.
* * * * *