U.S. patent application number 15/677217 was filed with the patent office on 2018-02-15 for heat exchanger device.
The applicant listed for this patent is HS Marston Aerospace Limited. Invention is credited to Hugh MacLellan.
Application Number | 20180045472 15/677217 |
Document ID | / |
Family ID | 56985976 |
Filed Date | 2018-02-15 |
United States Patent
Application |
20180045472 |
Kind Code |
A1 |
MacLellan; Hugh |
February 15, 2018 |
HEAT EXCHANGER DEVICE
Abstract
A multilayer heat exchanger device comprises: a stack of double
sided plates arranged to provide multiple fluid flow paths
separated by the plates; wherein the double sided plates each have
an array of heat exchanger fins extending outward from both sides
of a body of the plate into the fluid flow paths on either side of
the plate; and wherein outer ends of the fins of the double sided
plates are bonded on each side of the plates to the fins, or
between the fins, of the adjacent plates. The double sided plates
may be manufactured by etching.
Inventors: |
MacLellan; Hugh; (Brackely,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HS Marston Aerospace Limited |
Wolverhampton |
|
GB |
|
|
Family ID: |
56985976 |
Appl. No.: |
15/677217 |
Filed: |
August 15, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 9/0062 20130101;
F28D 9/0031 20130101; F28F 21/065 20130101; F28D 2021/0021
20130101; F28F 21/04 20130101; F28F 3/048 20130101; F28F 21/084
20130101; F28F 3/08 20130101; F28F 2275/04 20130101; F28F 2240/00
20130101; F28F 3/022 20130101; F28F 3/044 20130101; F28F 21/085
20130101 |
International
Class: |
F28F 3/08 20060101
F28F003/08; F28F 21/08 20060101 F28F021/08; F28F 3/02 20060101
F28F003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 15, 2016 |
GB |
1613918.0 |
Claims
1. A multilayer heat exchanger device comprising: a stack of double
sided plates arranged to provide multiple fluid flow paths
separated by the plates; wherein the double sided plates each have
an array of heat exchanger fins extending outward from both sides
of a body of the plate into the fluid flow paths on either side of
the plate; and wherein outer ends of the fins of the double sided
plates are bonded on each side of the plates to the fins, or
between the fins, of the adjacent plates.
2. A multilayer heat exchanger device as claimed in claim 1,
wherein the heat exchanger device is arranged for forced flow of
fluid through the fluid flow paths.
3. A multilayer heat exchanger device as claimed in claim 1,
wherein the fins are heat exchanger pins that extend from the body
of the plates in a columnar fashion.
4. A multilayer heat exchanger device as claimed in claim 3,
wherein the pins form an array with pins distributed across the
body of the plate in a grid pattern.
5. A multilayer heat exchanger device as claimed in claim 1,
wherein the fin ends of some or all plates are bonded to fins of
the adjacent plate such that there are abutting fin ends at the
join between adjacent plates.
6. A multilayer heat exchanger device as claimed claim 1, wherein
the fin ends of some or all plates are joined to the adjacent plate
between the fins of the adjacent plate and bonded to the body of
the adjacent plate such that the fins of adjacent plates are
interleaved with fins of a first plate being either side of a fin
of the second plate and vice versa.
7. A multilayer heat exchanger device as claimed in claim 5,
wherein the heat exchanger device includes some pairs of adjacent
plates where the fin ends are joined and other pairs of adjacent
plates where the fins are interleaved.
8. A multilayer heat exchanger device as claimed in claim 1,
wherein the spacing between adjacent plates is in the range 2 to 10
mm, the fins have a minimum width in the range 0.5 to 2 mm, the
spacing between centres of adjacent fins is in the range 1 to 10 mm
and the fins extend from the body of the plate by 1 to 10 mm.
9. A multilayer heat exchanger device as claimed in claim 1,
wherein the spacing between the centres of the fins is less than
three times the minimum width of the fins.
10. A multilayer heat exchanger device as claimed in claim 1,
wherein the double sided plates are formed in a single piece.
11. A multilayer heat exchanger device as claimed in claim 1,
wherein the plates are formed by etching away material on both
sides of a blank plate with a suitable mask that is arranged to
leave the fins extending outward from the body of the etched
plate.
12. A multilayer heat exchanger device as claimed in claim 1,
wherein the double sided plates comprise aluminium.
13. A multilayer heat exchanger device as claimed in claim 1,
wherein the fin ends are bonded to the adjacent plate by
brazing.
14. A multilayer heat exchanger device as claimed in claim 1,
wherein the heat exchanger device is a multilayer structure with at
least 40 plates arranged in a repeating pattern in respect to the
flow of fluids.
15. A multilayer heat exchanger device as claimed in claim 1,
wherein the heat exchanger device includes end plates with fins
extending from only one side of the body of the plate and with the
other side of the body of the end plates forming an outside surface
of the heat exchanger device and having no fins.
16. A multilayer heat exchanger device as claimed in claim 1,
wherein the heat exchanger is for aerospace use.
17. An aircraft including a multilayer heat exchanger device as
claimed in claim 1.
18. A method of manufacturing a multilayer heat exchanger device
comprising: forming multiple double sided plates, each plate having
an array of heat exchanger fins extending outward from both sides
of a body of the plate; and assembling the heat exchanger device by
layering the double sided plates into a stack in order to provide
multiple fluid flow paths separated by the plates; wherein the fins
extend outward from both sides of the body of the plates into the
fluid flow paths on either side of the plates; and wherein the
assembly of the stack includes bonding outer ends of the fins on
each side of the double sided plates to the fins, or between the
fins, of the adjacent plates.
19. A method as claimed in claim 18, comprising forming the double
sided plates.
20. A method as claimed in claim 18, comprising etching away
material on both sides of a blank plate using a suitable mask that
is arranged to leave the required fins extending outward from the
body of the etched plate.
Description
FOREIGN PRIORITY
[0001] This application claims priority to Great Britain Patent
Application No. 1613918.0 filed Aug. 15, 2016, the entire contents
of which is incorporated herein by reference.
TECHNICAL FIELD
[0002] The invention relates to a heat exchanger device and to a
method for manufacturing a heat exchanger device. In an example
implementation the heat exchanger device is for aerospace use.
[0003] Heat exchangers for transfer of heat between different
fluids are very widely used and exist in various forms. Typically
heat exchangers are arranged for flow of a primary fluid and a
secondary fluid with heat being transferred between the two fluids
as they flow through the device. Multi-stream heat exchangers for
exchanging heat between more than two fluids also exist in the
prior art. Some heat exchangers have a layered structure with a
large number of parallel flow paths between plates that separate
the flow paths. There may be 50-200 plates, or more, in this type
of heat exchanger, typically with alternating hot/cold fluid flow
paths either side of each plate. Such heat exchangers can also be
referred to as laminate heat exchangers.
[0004] The plates generally have features to promote heat transfer
and/or turbulent flow of the fluids, such as protrusions extending
outward from the body of the plates into the flow of fluid. These
features are referred to generally as fins, which includes various
geometries of fins forming chambers within the flow passages, such
as straight-finned triangular or rectangular arrangements;
herringbone, where the fins are placed sideways to provide a
zig-zag path; serrated and/or perforated fins, which include cuts
and perforations in the fins to augment flow distribution and
improve heat transfer; as well as pin fins, where the fins are
columnar shapes extending outward from the body of the plates,
typically normal to the plane of the plates.
[0005] U.S. Pat. No. 8,616,269 discloses an example of a pin fin
heat exchanger device with multiple layers. Multiple double sided
plates are arranged in a stack with spaces between surfaces of the
plates and adjacent plates enclosing fluid flow paths for a first
fluid and a second fluid. Pins extend from one or both sides of the
plates toward the adjacent plate(s), so that the pins extend into
the fluid flow paths. The pins can be formed separately to the
plates and mounted to the plates. In particular, the pins are
inserted through the plates using through holes. Alternatively the
pins can be formed integrally with the plate or plates by chemical
etching. The pins can pass through multiple plates. In some cases
the pins extending from one plate may have their ends facing the
ends of pins extending from the adjacent plate, in which case the
heat exchanger device of U.S. Pat. No. 8,616,269 is formed with a
gap between the pin ends.
SUMMARY
[0006] Viewed from a first aspect, the invention provides a
multilayer heat exchanger device comprising: a stack of double
sided plates arranged to provide multiple fluid flow paths
separated by the plates; wherein the double sided plates each have
an array of heat exchanger fins extending outward from both sides
of a body of the plate into the fluid flow paths on either side of
the plate; and wherein outer ends of the fins of the double sided
plates are bonded on each side of the plates to the fins or between
the fins of the adjacent plates.
[0007] This arrangement provides a high degree of flexibility in
terms of the spacing of the fins and the spacing between the
plates, whilst also ensuring that the device is strong, with a
structure that can be both lightweight and stiff. In contrast to
U.S. Pat. No. 8,616,269, where some or all of the fin pins have
free ends, the fin ends in the above aspect are bonded to a part of
the adjacent plate, which means that every layer is connected to
the adjacent layer with a relatively rigid join, and with
attachment points extending across the area of the plates. At least
a majority of the fin ends may be bonded to the adjacent plate,
optionally all of the fin ends. In addition, since the plates are
double sided then unlike U.S. Pat. No. 8,616,269 the pins extend
inward into the flow paths from both sides, rather than just from
one side as is the case for some of the layers in U.S. Pat. No.
8,616,269. The combination of strength and low weight has
particular advantages for aerospace applications, and will also
have benefits in any other use for a heat exchanger where weight,
strength and stiffness are beneficial properties. The bonding of
the fins to the adjacent plate may also provide enhancements in the
heat exchanging characteristics of the device.
[0008] A multilayer heat exchanger device of the type set out in
the first aspect has many layers with multiple fluid flow paths
each being arranged for heat exchange with adjacent fluid flow
paths. The fluid flow paths may all be in parallel planes, and may
have parallel flow paths with the same or opposed directions of
flow. Thus, the plates may be generally planar in order that
adjacent plates enclose a fluid flow path with the principle flow
direction being parallel with the planes of the adjacent plates. A
typical heat exchanger device has primary and secondary fluids
flowing in parallel paths in different directions, which maximises
the temperature differential between the fluids and thus gives the
greatest rate of heat transfer. Such a heat exchanger device is to
be differentiated from a heat sink in that heat transfer is
promoted via flow of the fluid through the flow paths rather than
occurring with passive convection of fluid away from the heat
exchange elements as it is heated or cooled. Thus, the heat
exchanger may be arranged for forced flow of fluid through the
fluid flow paths, for example by being coupled via fluid inlets and
outlets to incoming and outgoing fluid passages with a differential
pressure. The fluid inlets and outlets may be common to multiple
flow paths, for example with a first set of inlets and outlets for
a first fluid and a second set of inlets and outlets for a second
fluid, the first and second fluids having different temperatures at
the respective inlets and heat being transferred between the first
and second fluids as they flow through the heat exchanger.
[0009] The array of fins advantageously includes multiple fins
distributed across the surface of the body of the plate, and these
may all extend in generally the same direction from the body of the
plate, for example they may all extend generally perpendicular to a
surface of the body of the plate. The bodies of the plates may be
generally planar and may extend across a two dimensional area of
the volume of the heat exchanger device. The fins extending from
either side of the double sided plate may have a similar or an
identical pattern, and may be aligned with each other or may be
offset from one another. Using a double sided plate with fins that
are offset on either side means that multiple similar plates can be
stacked in the same orientation with interleaved fins without the
need to offset the bodies of the plates. An offset type plate
design could also be used for fins that join at the fin ends by
reversing the orientation of the plate in each adjacent layer. It
is preferred for the multiple double sided plates to be similar to
one another.
[0010] In example embodiments the fins are heat exchanger pins and
hence they may extend from the body of the plates in a columnar
fashion. The pins may have a circular cross-section. The pins may
form an array with pins distributed across the body of the plate in
a grid pattern, such as a square or diamond grid pattern. A diamond
grid pattern in this sense has a line between opposite corners of
the diamond aligned with the flow direction of the fluid flow path,
whereas a square grid pattern has two sides of the square aligned
with the flow direction. A diamond grid pattern has adjacent rows
of pins that are staggered and this can aid heat transfer. One
example uses a diamond grid pattern with right angled corners,
which has staggered rows of pins and equal spacing between all
adjacent pins.
[0011] The fins that extend toward each other from adjacent plates
may be arranged in an array with a similar or identical pattern. As
noted above the fin ends may be bonded to fins of the adjacent
plate and thus there may be abutting fin ends at the join between
adjacent plates. Alternatively the fin ends may be joined to the
adjacent plate between the fins of the adjacent plate, and thus
they may be bonded to the body of the adjacent plate. In the latter
case the fins of adjacent plates may be interleaved in a repeating
arrangement with fins of a first plate being either side of a fin
of the second plate, and vice versa. The heat exchanger device may
have a combination of these arrangements and hence may include some
adjacent plates where the fin ends are joined and other adjacent
plates where the fins are interleaved. It should be noted that the
interleaved arrangement does not of course apply to fins at the
outer edges of the plates, since there would be no adjacent fin on
the outside of the outermost fins. All of the fins aside from the
outermost fins may be interleaved with fins from the adjacent
plate.
[0012] The fin ends may be shaped such that they can be bonded
effectively to the adjacent plate. For example the ends may be
substantially flat in order to be placed against and bonded to a
flat surface at the fin ends or between the fins of the adjacent
plate, or the fin ends may be curved in order to fit with a curved
surface of the adjacent plates, for example a curved surface of a
recess between the fins of the adjacent plate.
[0013] The heat exchanger fins may have any suitable size and
shape, and the spacing between the fins and/or between adjacent
plates may be set as required based on the particular intended use
for the heat exchanger device. In example implementations, which
may have advantages for use in aerospace, the spacing between
adjacent plates may be in the range 1 to 30 mm, optionally in the
range 2 to 10 mm, the fins may have a minimum width (which may be a
diameter of a pin fin) in the range 0.25 to 10 mm, optionally in
the range 0.5 to 2 mm and/or the spacing between centres of
adjacent fins (i.e. the pitch of the fins) may be in the range 0.5
to 20 mm, optionally in the range 1 to 10 mm. The fins may extend
from the body of the plate by 0.5 to 30 mm, optionally by 1 to 10
mm. The total thickness of the double sided plates may be 1.5 to 70
mm, optionally 2 to 30 mm. The dimensions and spacing of the fins
may be the same for each plate in the heat exchanger device, or
alternatively the dimensions and spacing may differ for different
plates.
[0014] It will be understood that in the case where fin ends of
adjacent plates are bonded together then the spacing between the
plates will be the sum of the distances that the fins extend
outward from the adjacent plates, i.e. twice the distance if the
fins have a similar size, and the spacing between the fin centres
of adjacent fins will be the same as the spacing between fins on
each plate. Alternatively, in the case where the fins are
interleaved and the fin ends are bonded to the adjacent plate in
between the fins of that plate then the spacing between plates will
be the same as the distance that the fins extend outward from the
plates and the spacing between centres of adjacent fins will be the
spacing between the interleaved fins, and hence half of the spacing
between the centres of the fins on each plate if the fins on each
plate have the same spacing and are evenly distributed. In the
latter case the fins on the adjacent plates should extend outward
from both of those plates by the same distance in order to permit
both sets of fin ends to join to and be bonded to the plate at the
opposite side.
[0015] In some examples the fins extend from the body of the plate
by up to five times the minimum width or diameter of the fins,
optionally between one and two times the width or diameter of the
fins. The spacing between the fins may be less than three times the
minimum width or diameter of the fins, optionally less than two
times the minimum width or diameter of the fins. When the fins are
interleaved then the spacing may be smaller than when the fins meet
with the ends of fins from the opposite plate. It can be an
advantage to have the fins close together in order to increase the
heat transfer by maximising the ratio of the exposed surface area
of the fins to the volume of the fluid. In this discussion the
minimum width or diameter of the fins is referenced to take account
of the fact that in many cases, for example where the fins are
manufactured by chemical etching, the fins will not have a uniform
width or diameter along the whole of their extent from the body of
the plate to the fin ends. The fins may have the minimum width or
diameter at the fin ends.
[0016] In the case where the fins are pins then the width
measurements referenced above will be diameters of the pins. The
spacing between the centres of the pins may refer to the smallest
distance between a pin and nearby pins in the array of pins, which
may for example be the length of a side of a grid pattern when the
pins are in a grid pattern, i.e. the length of the side of the
square in a square grid pattern or the length of a side of the
diamond in a diamond grid pattern.
[0017] The double sided plates may advantageously be formed in a
single piece, and hence may comprise a homogeneous body of material
with no bonding between separate parts. This might be achieved by
the use of machined, moulded, cast, forged or stamped plates, for
example. Additive manufacturing techniques may also be used to make
the plates. One implementation of single piece plates uses chemical
etching to form the structure of the plates. Thus, the plates may
be formed by etching away material on both sides of a blank plate
with a suitable mask that is arranged to leave the required fins
extending outward from the body of the etched plate. The use of a
single piece with a homogeneous body of material provides
advantages in relation to heat transfer and strength of the plates,
which then further enhances the advantages of the heat exchanger
device when multiple such plates are bonded together via the fin
ends as in the first aspect. All of the plates may be manufactured
with the same technique, for example all plates may be etched.
[0018] Producing fins such as pins by etching has the result that
there is not a constant cross-section along the extent of the fins.
The base of the fins will typically be somewhat wider than the ends
of the fins due to the etching process. This can provide benefits
from added strength, but it limits the minimum spacing between fins
on each plate. It is therefore beneficial to combine the feature of
double sided etched plates with the use of interleaved fins, which
allows for the spacing between fins to be reduced whilst also
retaining the benefits of manufacturing by etching. Thus, in one
example some or all of the double sided plates are etched and some
or all of adjacent pairs of the etched plates have interleaved
fins, with the fin ends bonded to the body of the adjacent plate in
between fins of the adjacent plate.
[0019] The heat exchanger device may be for use with any required
combination of fluids, such as liquid-liquid, liquid-gas or gas-gas
heat exchange. The heat exchanger may use air for heating or
cooling of another fluid. In some examples the heat exchanger is
for aerospace use and the invention thus extends to an aircraft
including the heat exchanger device. In context of aerospace use
the fluids could include two or more of: atmospheric air, cabin
air, engine oil, generator oil, coolant, fuel and so on.
[0020] The material of the double sided plates may be selected
bearing in mind the intended use of the device and limitations
arising from the temperatures and fluids involved in the use of the
device. In particular, in some cases the material may be selected
to withstand high or low temperatures, or to be resistant to
chemically reactive fluids such as fuel or coolant. In one example
the double sided plates comprise aluminium and may be an aluminium
alloy. Alternatively a stainless steel or copper based material may
be used. It will be appreciated that metals such as aluminium can
be readily etched, and that they provide a high conductance of
heat. Non-metallic materials may also be used, such as ceramic or
plastic materials.
[0021] The method used for bonding the fin ends to the adjacent
plates may be selected based on the materials that are involved.
Where metals such as aluminium alloys are used then brazing is a
suitable joining technique.
[0022] The heat exchanger device is a multilayer structure with
many plates, generally arranged in a repeating pattern in respect
to the flow of fluids. There may for example be at least 40 plates,
optionally at least 60 plates and in some cases 100 or more plates.
The size and flow capacity of the heat exchanger device increases
with the addition of more plates, which adds more flow paths, and
thus more plates may be added as required to provide the necessary
performance. The heat exchanger device may have a laminate
structure, with the multiple plates coupled together by the bonding
of the fin ends to adjacent plates and optionally also by a frame
or supporting structure that clamps the plates together. The
thickness of the heat exchanger device as a whole is set by the
plate thickness, the number of plates, and whether the fins are
interleaved or meet at the fin ends.
[0023] The heat exchanger device may be finstock provided as a part
of a larger heat exchanger system, with this larger heat exchanger
system comprising fluid inlet and outlet passages as well as
optionally other features such as a frame for supporting the
finstock and manifold structures for distribution of fluid to the
flow paths. Alternatively the heat exchanger device may include
fluid inlet and outlet passages and/or manifold structures coupled
to or optionally integrated with the double sided plates. In either
case the heat exchanger device may utilise the strength and
stiffness of the layered double sided plates to provide strength
and stiffness to the device as a whole. In either case the heat
exchanger device may include end plates of differing form to the
double sided plates, for example the end plates may have fins
extending from only one side of the body of the plate and with the
other side of the body of the plate forming an outside surface of
the heat exchanger device and having no fins. Thus, the end plates
may be single sided plates. In some examples the heat exchanger
device may have to end plates and multiple double sided plates in
between the end plates, optionally with only double sided plates in
between the end plates.
[0024] The manifolds may include a least a primary fluid inlet
manifold, primary fluid outlet manifold, a secondary fluid inlet
manifold and a secondary fluid outlet manifold. Thus, the heat
exchanger device may be used for heat exchange with at least two
fluids. Further manifolds could be added to allow for multistream
arrangements with more than two fluids.
[0025] As noted above, the heat exchanger device may be arranged
for flow of two or more fluids in flow paths between the double
sided layers. At the outer ends of the heat exchanger device the
flow paths may optionally be between single sided end plates and a
double sided plate adjacent to the end plate. Flow paths defined
between generally planar plates will be in parallel planes, with
heat transfer occurring generally perpendicular to the planes. The
heat exchanger device may be arranged with multiple identical flow
paths formed by repeating identical double sided plates in the
stack. This might be used with alternating fluids in adjacent flow
paths, such that a first fluid flows through the first, third and
subsequent flow paths, and a second fluid flows through the second,
fourth and subsequent flow paths. Alternatively there may be a need
for a greater flow cross-section for one fluid, in which case that
fluid may be flowed through two adjacent flow paths alternating
with one flow path for another fluid, such as by having a first
fluid in the first, fourth and seventh flow paths and subsequently
in every third flow path and a second fluid in the second and third
flow paths, then the fifth and sixth flow paths, and so on.
Sometimes there are differing restrictions or requirements on the
pressure drop and/or volume flow rate of one fluid compared to the
other. Another possible way to provide for an increased volume flow
rate and/or lower pressure drop for one fluid compared to another
(without the use of different plate designs) is to vary the
arrangement of the double sided plates, for example to alternate
interleaved fins with fins that meet at the fin ends. A flow path
through interleaved fins has a smaller cross-section and hence a
smaller volume than a flow path through similar fins that meet at
the fin ends, since the plates are further apart and the fins
obstruct relatively less of the flow path.
[0026] Viewed from a second aspect, the invention provides a method
of manufacturing a multilayer heat exchanger device comprising:
forming multiple double sided plates, each plate having an array of
heat exchanger fins extending outward from both sides of a body of
the plate; and assembling the heat exchanger device by layering the
double sided plates into a stack in order to provide multiple fluid
flow paths separated by the plates; wherein the fins extend outward
from both sides of the body of the plates into the fluid flow paths
on either side of the plates; and wherein the assembly of the stack
includes bonding outer ends of the fins on each side of the double
sided plates to the fins or between the fins of the adjacent
plates.
[0027] This method allows for effective manufacture of the heat
exchanger device of the first aspect. The method may include
forming the double sided plates and/or assembling the heat
exchanger device with any of the features discussed above. The
double sided plates may be similar or alternatively multiple
designs of plates may be used. The multiple fluid flow paths formed
between the double sided plates may be similar or they may differ
in terms of the arrangement of the fins, the spacing of the plates
and so on, again as discussed above. The method may include
changing the orientation and/or offset of the plates when each of
the plates is added to the stack, and/or selecting a different type
of plate when each of the plates is added to the stack. Single
sided end plates may be used as discussed above. The stack of
plates may include any arrangement of and/or number of plates as
discussed above, for example with parallel flow paths and so on.
The step of assembling the heat exchanger device may include
joining the layered double sided plates to manifolds for
distribution of fluid during use of the heat exchanger device, such
as the manifolds discussed above.
[0028] The method may include forming the double sided plates in a
single piece, and hence they may comprise a homogeneous body of
material with no bonding between separate parts. This might be
achieved by the use of machined, moulded, forged or stamped plates,
for example. One method for forming single piece plates includes
using chemical etching to form the structure of the plates. Thus,
the method may include etching away material on both sides of a
blank plate using a suitable mask that is arranged to leave the
required fins extending outward from the body of the etched plate.
All of the plates may be manufactured with the same technique, for
example all plates may be etched.
BRIEF DESCRIPTION OF THE FIGURES
[0029] Preferred embodiments of the invention are described below
by way of example only and with reference to the accompanying
drawings, in which.
[0030] FIG. 1 is a cross-section view showing significant
dimensions for two single sided heat exchanger plates in a layered
arrangement;
[0031] FIG. 2 is a diagram showing some of the same dimensions in a
plan view of a part of a pin fin heat exchanger plate;
[0032] FIG. 3 illustrates the use of etching to manufacture pin
fins on a single sided plate;
[0033] FIG. 4 is a top perspective view of a single sided plate
produced in accordance with the etching technique of FIG. 3;
[0034] FIG. 5 shows a layered heat exchanger device made up of
multiple single sided plates of the type shown in FIG. 4;
[0035] FIG. 6 shows a double sided plate with pins extending from
two sides of the body of the plate where the pins are offset on
each side;
[0036] FIG. 7 is a side view of a layered heat exchanger device
made up of multiple double sided plates of the type shown in FIG. 6
with pins of adjacent layers interleaved;
[0037] FIG. 8 is a cross-section of the device shown in FIG. 7;
[0038] FIG. 9 is a similar diagram to that of FIG. 1 showing the
changes in the dimensions between two plates with the interleaved
double sided plates of FIGS. 7 and 8;
[0039] FIG. 10 shows another double sided plate with pins extending
from two sides of the body of the plate where the pins of adjacent
layers are aligned on each side;
[0040] FIG. 11 is a side view of a layered heat exchanger device
made up of multiple double sided plates of the type shown in FIG.
10 with the pins of adjacent layers aligned with each other;
and
[0041] FIG. 12 is a cross-section of the device shown in FIG.
11.
DETAILED DESCRIPTION
[0042] Embodiments of a heat exchanger device with double sided
plates can be considered as an improvement over similar devices
manufactured with single sided plates. FIG. 1 illustrates a
stacking arrangement of two such single sided plates 12. Each of
the single sided plates 12 has an array of fins 14 protruding from
one side. The fins 14 extend from a body 16 of the plate and might
for example be pin fins 14 arranged in a grid pattern. The fins 14
are spaced apart with a pitch P, which is the distance between the
centres of the fins 14. The spacing p between outer surfaces of the
pins is the difference between the pitch P and the fin diameter D.
In this case all of the pins 14 have the same diameter D. The plate
12 has a total height h, including the height of the fins 14 and
the thickness t of the body 16. In the example of a single sided
plate 12 given here the stack of plates is joined together by
brazing in order to bond the ends of the fins 14 to the underside
of the next plate 12. This process results in a change in the
height of the fins 14, with the post braze height of the fin 14 and
plate 12 being shown as hb in FIG. 1.
[0043] FIG. 2 illustrates some further parameters that might be
measured in connection with arrays of pin fins 14 on the body 16 of
the plate 12. As shown in FIG. 2 adjacent rows of fins 14 can be
staggered so that they are arranged in a diamond-like grid pattern
with a pitch angle .alpha. between an axis of the plate 12 and a
line intersecting the centres of the pin fins 14. The transverse
spacing St and the longitudinal spacing Sl may be the same, as
shown here, or they may differ. If the transverse spacing St and
the longitudinal spacing Sl are the same then the diamond grid is
essentially a square grid turned to a pitch angle .alpha. of 45
degrees.
[0044] It is beneficial to be able to maximise the number of fin
pins 14 per unit area of the plate 12. There are various
restrictions on the pitch P of the fin pins 14 as well as in some
cases on the transverse spacing St and the longitudinal spacing Sl.
These restrictions arise from the minimum sizes that can be formed
using the selected manufacturing process. For example, in the case
of etched pin fins 14 the pins 14 are not straight sided as shown
in FIG. 1, but instead have a curved conical profile as a
consequence of the etching process, as explained below with
reference to FIG. 3. A similar restriction can arise with other
manufacturing processes, for example the space required for moulds
and/or tooling can restrict the minimum spacing for pin fins 14
formed on machined, moulded, forged or stamped plates.
[0045] In an etching process, as shown in FIG. 3, a blank plate is
fitted with masks 20 on both sides and then exposed to an etchant,
for example by submersion in an acid 18. The masks 20 prevent the
etchant from etching away material beneath the masks 20 and thus if
an array of circular masks is used then an array of circular pin
fins 14 can be formed. However, since the etching process removes
material evenly across the exposed surface then the etched plate 12
has pins 14 with a curved conical profile as shown in the Figure.
For reference the dashed lines show the notional `ideal` shape with
straight sided pins 14. Etching provides advantages in terms of the
ease of manufacture of a relatively complicated shape and in the
final strength and heat transfer characteristics, but the curved
profile limits the minimum spacing of the fin pins 14 and thus
limits the spacing p between outer surfaces of the pins 14 and the
pitch P between the pins 14.
[0046] FIGS. 4 and 5 show respectively a single sided plate 12 and
a stack of single sided plates 12. Each of the plates 12 has an
array of pins 14 arranged in a diamond grid pattern with a pitch
angle .alpha. of 45 degrees. When the single sided plates 12 are
stacked, as shown in FIG. 5, then a flow path is formed between
each pair of adjacent plates, with the flow path passing through
the gaps between the pins 14 and being forced to flow around the
pins 14. This hence provides a heat exchanger device where a first
fluid can be flowed through one set of flow paths, for example the
first, third and fifth flow paths and so on, and a second fluid can
be flowed through the other set of flow paths, for example the
second, fourth and six flow paths and so on. Heat will be
transferred across the plates and the presence of the arrays of pin
fins 14 increases the effectiveness of the heat transfer. However,
the limitation on the spacing of the pin fins 14 is a disadvantage
of this arrangement.
[0047] An example of a double sided plate 22 is shown in FIG. 6 in
perspective view, and shown when utilised in a stack of plates in
FIGS. 7 and 8. The double sided plate 22 can advantageously be
formed using the same basic method as the single sided plate 12
described above, but with the addition that a thicker starting
plate is used and the blank plate is etched from both sides in
order to form arrays of pin fins 14 extending from both surfaces of
a body 16 of the plate 22. The plate 22 may be an aluminium alloy,
for example. These double sided plates 22 can then be stacked in
layers as shown in FIG. 7 and FIG. 8. It will be appreciated that
although the Figures show five plates stacked together in practice
they could be any number of plates and typically there would be
very many more than five plates, for example 50 or more or even 100
or more plates.
[0048] The double sided plates 22 of FIG. 6 have pin fins 14
arranged in a diamond grid pattern on both sides, but with an
offset for one side compared to the other. As a consequence of
this, when the plates 22 are layered together, the pin fins 14 are
interleaved with the fins 14 of one plate 22 extending between the
fins 14 of the adjacent plate 22. A result of this is that the
effective pitch P and the spacing p between surfaces of the pins 14
can be considerably reduced, despite the curved profile and the
limitations of the manufacturing process. This then provides for
increases in the number of pins per unit area, which can give rise
to increases in performance of the heat exchanger. The ends of the
pin fins 14 are bonded to the adjacent plate 22 in between the pin
fins 14 of the adjacent plate 22. Thus, as well as increased
numbers of pins per unit area this double sided arrangement can
also increase the strength of the device since there may be twice
as many points of contact and twice the area of bonds between
layers. The layers may be joined by brazing the ends of the pin
fins 14 to the recesses between the pin fins 14 of the adjacent
plate 22.
[0049] FIG. 9 is a similar diagram to FIG. 1 and shows the effect
of the double sided interleaved fin arrangement. In this diagram a
double sided plate 22 is placed on top of a single sided plate 12.
The single sided plate 12 may be the end plate of a stack of plates
12, 22 that forms the heat exchanger device, with subsequent layers
being made of double sided plates 22 in repeating arrangement
similar to the layers of FIGS. 7 and 8. There are pin fins 14
extending on both sides of the plate 22, which means that the pin
fins 14 can be interleaved as shown in the Figures and each of the
pin fins 14 (aside from the outermost pin fins 14) extends between
pin fins 14 of the adjacent plate. In the diagram of FIG. 9 the pin
fin 14 on the lower side of the double sided plate 22 extends
between the pin fins 14 on the upper side of the single sided plate
12. When further double sided plates 22 are stacked on top then
there can be interleaved pins 14 in each layer. The pitch P is half
that of FIG. 1, assuming that other dimensions remain the same. The
spacing p between the fins 14 is greatly reduced. The effect of
this is shown very clearly in the cross-section of FIG. 8, where
the small size of the passages between pin fins 14 can be seen.
[0050] Another arrangement for a double sided plate 22 is shown in
FIGS. 10 to 12. In this case the pin fins 14 are arranged in a
diamond grid pattern on each side and they are aligned with each
other on both sides of the body 16 of the plate 22. When these
double sided plates 22 are layered together, as shown in FIGS. 11
and 12, then the pins 14 can be aligned and the plates can be
joined by bonding ends of the pin fins 14 of one plate 22 to the
ends of the pin fins 14 of the adjacent plate 22. The spacing
between the two plates 22 is hence twice the height of the pin fins
14 and the pitch P of the pins 14 is similar to that of FIG. 1, but
with a much greater cross-section for the flow path between and
around the pins 14, as can be seen from FIG. 12. This arrangement
can be useful when the pressure drop through the heat exchanger
device is a design limitation.
[0051] It will be understood that the an arrangement with offset
pin fins 14 as shown in FIGS. 6-8 could also be used to provide an
arrangement with interconnected pin ends as in FIGS. 11 and 12, by
flipping the plates 22 over between each layer. The relative
location of the pin fins 14 could also be varied between layers by
offsetting the plates 22 relative to the adjacent plates 22. This
can move the pin fins 14 between a configuration in which they
align with the pin fins 14 of adjacent plates 22 and a
configuration in which they can be placed in between the pin fins
14 of adjacent plates. Thus, a single geometry for a double sided
plate 22 could be used to make a stacked heat exchanger device with
either interleaved pins 14, or interconnected pin ends 14, or a
combination of both arrangements in different layers of the
device.
[0052] A heat exchanger device comprising a layered structure as
shown in any of FIGS. 8 to 12 can be used as heat exchanger with
the addition of appropriate parts (not shown) to direct the flow of
fluid between the different layers. For example, in the case of a
heat exchanger for exchange of heat between a primary and a
secondary fluid there may be a primary fluid inlet manifold,
primary fluid outlet manifold, a secondary fluid inlet manifold and
a secondary fluid outlet manifold. Suitable enclosure bars or the
like may be used to ensure that fluid only enters/exits the
manifolds to or from specific layers. The manifolds may in turn be
connected to a broader system, for example a cooling or heating
system, which may have circuits for circulation of the fluids to
and from the heat exchanger device and other parts.
[0053] Although the present disclosure has been described with
reference to particular embodiments, the skilled reader will
appreciate that modifications may be made that fall within the
scope of the disclosure as defined by the appended claims. For
example, the Figures showing the double sided plates 22 have layers
of identical plates 22 each having similar arrangements of pin fins
14, but it will be appreciated that more complex arrangements could
be used, with differing configurations for the different plates 22
that are layered together and/or with varying arrangements of the
pin fins 14 on the two sides of each plate 22.
[0054] The term "about" is intended to include the degree of error
associated with measurement of the particular quantity based upon
the equipment available at the time of filing the application.
[0055] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the present disclosure. As used herein, the singular forms "a",
"an" and "the" are intended to include the plural forms as well,
unless the context clearly indicates otherwise. It will be further
understood that the terms "comprises" and/or "comprising," when
used in this specification, specify the presence of stated
features, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, integers, steps, operations, element components, and/or
groups thereof.
[0056] While the present disclosure has been described with
reference to an exemplary embodiment or embodiments, it will be
understood by those skilled in the art that various changes may be
made and equivalents may be substituted for elements thereof
without departing from the scope of the present disclosure. In
addition, many modifications may be made to adapt a particular
situation or material to the teachings of the present disclosure
without departing from the essential scope thereof. Therefore, it
is intended that the present disclosure not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this present disclosure, but that the present
disclosure will include all embodiments falling within the scope of
the claims.
* * * * *