U.S. patent application number 11/436405 was filed with the patent office on 2006-11-23 for heat exchanger core.
Invention is credited to Elena Khodak, Mark Theno.
Application Number | 20060260790 11/436405 |
Document ID | / |
Family ID | 37432127 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260790 |
Kind Code |
A1 |
Theno; Mark ; et
al. |
November 23, 2006 |
Heat exchanger core
Abstract
A heat exchanger core is fabricated from plastic sheets with a
flat side and a corrugated side. The plastic sheets are stacked so
that the corrugated sheets define two flow paths. The plastic
sheets is held in a stacked position by a retaining member.
Inventors: |
Theno; Mark; (Minnetonka,
MN) ; Khodak; Elena; (Hatfield, PA) |
Correspondence
Address: |
PATTERSON, THUENTE, SKAAR & CHRISTENSEN, P.A.
4800 IDS CENTER
80 SOUTH 8TH STREET
MINNEAPOLIS
MN
55402-2100
US
|
Family ID: |
37432127 |
Appl. No.: |
11/436405 |
Filed: |
May 18, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60682134 |
May 18, 2005 |
|
|
|
Current U.S.
Class: |
165/166 ;
165/905 |
Current CPC
Class: |
F28D 9/0062 20130101;
Y02B 30/56 20130101; Y02B 30/563 20130101; F28F 21/065 20130101;
F24F 12/006 20130101 |
Class at
Publication: |
165/166 ;
165/905 |
International
Class: |
F28F 3/00 20060101
F28F003/00 |
Claims
1. A heat exchanger core comprising a plurality of synthetic resin
layers, each layer having a liner member presenting a liner member
thickness, and a fluting member, the liner member and the fluting
member of each layer cooperatively defining a plurality of fluid
receiving channels presenting a fluid flow path along a fluid flow
path direction, at least some of said synthetic resin layers
oriented with each other such that said heat exchanger core
presents first and second fluid flow paths in different fluid flow
path directions, and at least some of said oriented layers
positioned adjacent each other with said first and second flow
paths being separated by a thickness of less than twice said liner
member thickness
2. The device of claim 1, wherein some of the layers are
rectangular.
3. The device of claim 1, wherein the plurality of synthetic resin
layers are stacked in a frame.
4. The device of claim 1, wherein the first and second fluid flow
path directions are generally transverse.
5. The device of claim 1, wherein one or more layers include
notches for receiving a retaining member.
6. The device of claim 1, further comprising a top member and a
bottom member including channels sized to receive a retaining
member.
7. The device of claim 6, wherein the retaining member comprises a
strap.
8. A heat exchanger comprising: a plurality of synthetic resin
layers, each layer having a liner member presenting a liner member
thickness, and a fluting member, the liner member and the fluting
member of each layer cooperatively defining a plurality of fluid
receiving channels presenting a fluid flow paths along a fluid flow
path direction, at least some of said synthetic resin layers
oriented with each other such that said heat exchanger core
presents first and second fluid flow paths in different fluid flow
path directions, and at least some of said layers positioned
adjacent each other with said first and second flow paths being
separated by a thickness of less than twice said liner member
thickness a retaining member for retaining the plurality of layers
in a stacked configuration; and a housing comprising a first
aperture and second aperture in communication with the first fluid
flow path and a first aperture and a second aperture in
communication with the second flow path.
9. The device of claim 8, wherein some of the layers are
rectangular.
10. The device of claim 8, further comprising a top member and a
bottom member having exterior surfaces with channels for receiving
the retaining member.
11. A method of making a heat exchanger core comprising the steps
of: providing a plurality of synthetic resin layers, each layer
having a liner member presenting a liner member thickness, and a
fluting member, the liner member and the fluting member of each
layer cooperatively defining a plurality of fluid receiving
channels presenting a fluid flow paths along a fluid flow path
direction, layering the plastic sheets so that at least some of
said synthetic resin layers are oriented with each other such that
said heat exchanger core presents first and second fluid flow paths
in different fluid flow path directions, and at least some of said
oriented layers positioned adjacent each other with said first and
second flow paths being separated by a thickness of less than twice
said liner member thickness; and retaining the plastic sheets in a
stacked configuration with at least one retaining member.
12. The method of claim 11, wherein some of the layers are
rectangular.
13. The method of claim 12, further comprising the step of
providing a top member and a bottom member, wherein the step of
retaining the plastic sheets in a stacked configuration comprises
securing the plurality of plastic sheets between the top member and
the bottom member.
14. The method of claim 13, wherein the top member and bottom
member comprise exterior surfaces having channels for receiving the
retaining member.
15. The method of claim 14, wherein the retaining member comprises
a strap.
16. The method of claim 12, wherein the retaining member comprises
a rectangular frame.
Description
RELATED APPLICATION
[0001] The present application claims the benefit of U.S.
Provisional Application No. 60/682,134 filed May 18, 2005, which is
incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a heat exchanger
core. More particularly, the present invention relates to a heat
exchanger core fabricated from single-face corrugated plastic, or
laminated corrugated plastic.
BACKGROUND OF THE INVENTION
[0003] To enhance the efficiency of many processes, it is desirable
to use heat exchangers that permit the exchange of heat from a gas
or liquid at a first temperature to a gas or liquid at a second
temperature, which is different than the first temperature. The
heat exchanger reclaims energy from a material that is being
discarded while raising the energy in a material that is being
input into the system, or vice versa.
[0004] For example, heating and air conditioning systems often
include a heat exchanger. Many manufacturing processes utilize heat
exchangers to reclaim energy from waste materials and thereby
reduce the costs associated with heating or cooling new
materials.
[0005] A heat exchanger core is the part of a heat exchanger where
materials at different temperatures are brought into proximity with
each other. Existing heat exchanger cores are generally made of
conductive materials, such as metal or plastic. Metallic heat
exchangers, such as those made from aluminum, are commonly used but
are much costlier to construct than ones made from plastic and
consequently are much more expensive for consumers.
[0006] U.S. Pat. No. 5,474,639 describes a double wall heat
exchanger made of polypropylene. The single die manufacturing
process used for this heat exchanger requires that two walls be
extruded for every flow path section. This double wall construction
reduces the amount of heat transfer available. Further, the
particular structure of the heat exchanger in U.S. Pat. No.
5,474,639, with its direction-dependent resistance to flow, causes
potential flow balancing problems.
[0007] Although plastic offers the advantages of lower cost and
lighter weight for the construction of heat-exchanger cores,
plastic does not generally offer the same high level of
conductivity that metal does. Existing plastic heat exchanger
cores, which use plastic sheets that are less conductive than metal
and stacked less efficiently, make plastic heat exchanger cores
generally less efficient than metal ones. What is needed is an
efficient plastic heat exchanger core that is relatively simple to
construct using inexpensive plastic sheets.
SUMMARY OF THE INVENTION
[0008] The problems outlined above are solved in part by a
heat-exchanger core made from single-wall corrugated plastic
sheets. The use of single-wall plastic sheets retains the
advantages of low cost and light weight offered by plastic while
also providing improved efficiency. The heat exchanger core
includes layers of plastic sheets with a generally planar side and
a corrugated side defining a plurality of channels, the channels
defining a flow path having a direction. The sheets are disposed in
layers and oriented so that two flow path directions are created.
The device includes a top layer and a bottom layer and a retaining
member for retaining the plurality of plastic sheets in a stacked
configuration between the top and bottom layers. Retention of the
plastic sheets may be facilitated by channels in the top and bottom
layers that receive straps. Or the plastic sheets may be mounted in
a frame between the top and bottom layers. The plastic sheets may
be provided with notches to facilitate framing. A method of
layering the plastic sheets so that two flow paths are created is
also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of a heat exchanger core of the
present invention.
[0010] FIG. 2 is a an enlarged, fragmentary, perspective view of
the heat exchanger core.
[0011] FIG. 3 is a perspective view of a first side of one of the
corrugated plastic sheets.
[0012] FIG. 4 is a perspective view of a second side of the
corrugated plastic sheet in FIG. 3.
[0013] FIG. 5 is a perspective view of an alternative configuration
of the heat exchanger core.
[0014] FIG. 6 is a plan view of a corrugated plastic sheet designed
for use in the embodiment shown in FIG. 5.
[0015] FIG. 7 is an enlarged, fragmentary, plan view of the
corrugated plastic sheet in FIG. 6.
[0016] FIG. 8 is a perspective view of a stack of the corrugated
plastic sheets shown in FIG. 6.
[0017] FIG. 9A is a perspective cross-sectional view of a heat
exchanger including the heat exchanger core.
[0018] FIG. 9B is an elevational cross-sectional view of the heat
exchanger showing the flow paths in the heat exchanger core.
DETAILED DESCRIPTION OF THE DRAWINGS
[0019] The present invention is a heat exchanger core as
illustrated at 10 in FIG. 1. The heat exchanger core 10 in
accordance with the present invention broadly includes a plurality
of corrugated plastic sheets 20 that are mounted in a frame 22.
[0020] The corrugated plastic sheets 20 are fabricated from a
single-face configuration having a substantially flat (planar)
first section or liner 30 and a corrugated (fluted) second section
32 that is affixed to the liner 30, as most clearly illustrated in
FIGS. 3 and 4. The fluting or corrugation of second section 32
together with liner 30 define a series of channels through which a
material, such as air, may flow.
[0021] The corrugated plastic sheets 20 are stacked so that
corrugations on adjacent corrugated plastic sheets are oriented
substantially transverse to each other, although other orientations
may also be used. Within the stack, each corrugated plastic sheet
is a layer. As shown in FIG. 1, corrugated plastic sheets 20 are
stacked in layers and the corrugations 32 of each alternating sheet
are oriented at 90-degree angles to define a first flow path and a
second flow path.
[0022] In the stack, liner 30 of each sheet 20 is oriented the same
way throughout so that liner 30 of one corrugated plastic sheet 20
contacts the corrugation 32 of adjacent sheets. As shown in FIG. 1,
the uppermost sheet 21 is oriented with liner 30 facing up. The
sheets below have the same orientation as the top sheet, so that
liner 30 of the bottom sheet 23 faces up and corrugation 32 faces
down. Alternatively, uppermost sheet 20 may be oriented with
corrugated surface 32 facing up. In this configuration (which can
be achieved simply by turning the previously described stack upside
down) the bottom sheet will also have corrugated surface 32 facing
up and liner 30 facing down. The designations "top" and "bottom"
are for convenience only, as it can be appreciated that inverting
the stack or corrugated plastic sheets 20 does not affect the
function of the heat exchanger core.
[0023] In addition to the corrugated plastic sheets 20, the heat
exchanger core 10 includes a top plate 40, a bottom plate 42, and
may include a plurality of mounting straps 44 as most clearly
illustrated in FIGS. 1 and 2. The top plate 40, the bottom plate
42, and the plurality of mounting straps 44 facilitate maintaining
the heat exchanger core 10 in a substantially rigid
configuration.
[0024] The top plate 40 and the bottom plate 42 each include
channels 46 formed in their exterior surfaces. The channels 46 are
sized to receive the mounting straps 44 and geometrically spaced to
prevent the mounting straps 44 from moving laterally on the top
plate 40 and the bottom plate 42. As shown in FIG. 1, when mounting
straps 44 are secured in channels 46 on top plate 40 and bottom
plate 42, and positioned securely around the stack of corrugated
plastic sheets 20, they collectively form frame 22.
[0025] In an embodiment, the corrugated plastic sheets 20 are
fabricated from high-density polyethylene (HDPE), or other
synthetic resins. HDPE is more flexible than other commercial
plastics, which makes the sheets less expensive to construct and
transport. Other plastic materials, such as polypropylene, may also
be used to manufacture corrugated plastic sheets 20. The
heat-transfer coefficient of the sheet material should be 60% or
better. In alternative embodiments, various dopants may be added to
the synthetic resin to improve the conductive properties of the
material.
[0026] To facilitate good heat transfer in the heat exchanger core
10, liner 30 and corrugation 32 are fabricated with a relatively
small thickness. Preferably, liner 30 and corrugation 32 each have
a wall thickness of less than 0.25 inches and greater than 0.0001
inches.
[0027] The corrugated plastic sheets 20 have a thickness of less
than 1 inch and greater than 0.001 inches. Spacing between
individual corrugations 34 is less than 1 inch and greater than
0.001 inches. In some embodiments, the thickness of corrugation 32
and liner 30 may be different from each other. In these
embodiments, the thickness of liner 30 may be reduced to improve
thermal transfer.
[0028] The corrugated plastic sheets 20 are molded of synthetic
resin in a two-part die where one part of the die extrudes liner 30
and a second die extrudes corrugation 32. The materials extruded
from the first die and the second die are placed in contact with
each other when in a slightly molten form so that the liner 30 and
corrugation 32 bond together.
[0029] The corrugated plastic sheets 20 are fabricated with a
length and width that are selected based upon the desired use of
the heat exchanger core 10. For most applications, the corrugated
plastic sheets 20 would include an equilateral rectangle or
parallelogram. The width and length of the corrugated plastic
sheets are each between about three inches and eight feet.
[0030] As an example, when the heat exchanger core 10 is fabricated
with a width and length that are both about 12 inches and there are
42 corrugated plastic sheets in the first direction and 41
corrugated plastic sheets in the second direction, the heat
exchanger core 10 provides a total contact area for the first
material of approximately 25,000 square inches and a total contact
area for the second material of approximately 25,000 square
inches.
[0031] Since the heat transfer coefficient of plastic is greater
than the heat transfer coefficient of some materials, such as air,
increase of the surface area of the heat exchanger core 10 enables
more heat to be extracted from the materials flowing through the
heat exchanger core 10.
[0032] Because of the structure of the heat exchanger core 10, the
heat exchanger core 10 also exhibits a low resistance. As a result
of the low velocity in the channels or flutes and the low
resistance, a low driving force is needed to move materials through
the heat exchanger core 10.
[0033] The heat exchanger core 10 of the present invention provides
good heat transfer characteristics when used in a variety of
applications such as heating, ventilation and air conditioning. The
heat exchanger 10 resists corrosion because the corrugated sheets
are fabricated from plastic.
[0034] Forming the heat exchanger core 10 from plastic corrugated
sheets 20 also reduces the cost associated with manufacturing the
heat exchanger core when compared with heat exchanger cores that
are fabricated from metallic materials such as aluminum. Although
the heat-transfer properties of plastics are generally less
desirable than those of metallic materials, the use of single-face
corrugated sheets offsets this in part.
[0035] Single-face corrugated plastic sheets 20 can be stacked so
that liner 30 of one sheet does not rest on liner 30 of an adjacent
sheet 20 Corrugation 32 of each sheet contacts liner 30 of an
adjacent sheet. Likewise, liner 30 of each plastic sheet contacts
corrugation 32 of an adjacent sheet. In such a configuration,
adjacent liners 30 do not touch, thus preventing the formation of a
double thickness of liners 30 in the stack of plastic corrugated
sheets 20 and ensuring that each liner 30 is exposed to flow
directly on either side through channels defined by corrugation
32.
[0036] In an alternate configuration shown in FIG. 5, heat
exchanger core 80 includes top member 81, a plurality of corrugated
plastic sheets 82, and bottom member 83 in a frame 84 that extends
along each of the edges of the device. The frame 84 generally
includes L-shaped pieces 85 that prevent the corrugated plastic
sheets 82 from moving. Frame 84 also includes fasteners 86 that
connect L-shaped pieces 85 to top frame members 87, which enclose
top member 81. Bottom frame members 88 are similarly joined to
L-shaped pieces 85 and enclose bottom member 83. The frame 84 may
be fabricated from plastic or a metallic material such as aluminum.
As in the embodiment of FIG. 1, the heat exchanger core 80 includes
a plurality of corrugated plastic sheets 82 that are arranged so
that adjacent corrugated plastic sheets 82 are oriented
substantially transverse to each other, although other orientations
may also be used. Corrugated plastic sheet 82 is constructed like
corrugated plastic sheet 20.
[0037] In a variation of the embodiment shown in FIG. 5, a modified
corrugated plastic sheet 120 is adapted to receive side frame
elements (not shown), as illustrated in FIGS. 6 and 7. Proximate
intersection of sides 122 of the corrugated sheet 120 a notch 124
is formed in the corrugated sheet 120.
[0038] The notch 124 includes a pair of side walls 130 and a base
wall 132 that extends between the side walls 130 so that the notch
124 has a U-shaped configuration. Forming the notch 124 with this
configuration prevents the side frame elements from moving out of
the notch 124 by sliding laterally. In other respects, corrugated
plastic sheet 120 is constructed like corrugated plastic sheets 20
and 82.
[0039] Corrugated plastic sheets 120 are used to construct a heat
exchanger core that includes a top plate (not shown) and a bottom
plate (not shown) that are both attached to the side frame
elements. Using this configuration of the corrugated sheet 120
enables the heat exchanger core to have outer dimensions that are
approximately the same as the dimensions of the corrugated sheet.
This can be seen from FIG. 8, which shows how a stack of corrugated
plastic sheets 120 facilitates framing. The choice of frame members
could be either a rigid frame member similar to that shown in FIG.
5 or bands as shown in FIG. 1.
[0040] Heat exchanger core 10 may be used as part of a heat
exchanger 140 as shown in FIGS. 9A-9B. Heat exchanger 140 generally
comprises a housing 142 sized to receive heat exchanger core 10. A
flow path in housing 142 in a first direction 144 is formed by
aperture 146 and aperture 148. A flow path in housing 142 in a
second direction 150 is formed by aperture 152 and aperture 154. As
shown in FIG. 9A-9B, heat exchanger core 10 is angularly disposed
inside housing 142 so that the geometry of heat exchanger core 10
contributes to the formation of two distinct flow paths. The angle
and disposition of heat exchanger core 10 inside housing 142 may be
varied. Apertures 146, 148, 152, and 154 may have a variety of
shapes and be positioned at other positions in housing 142.
[0041] In operation, the heat exchanger core 10 is used with a
first material flowing in a first direction (as indicated by arrow
100 in FIG. 1) and a second material flowing in a second direction
(as indicated by arrow 102 in FIG. 1). The heat exchanger core 10
thereby permits heat to be transferred from the first material to
the second material.
[0042] In an embodiment, the first material and the second material
are both air. One or both of the materials, however, may be another
fluid or gas.
[0043] The heat exchanger core 10 of the present invention is
suited for use in a variety of heat transfer applications. One
application for which the heat exchanger core 10 is particularly
suited is heat-recovery ventilators or energy-recovery ventilators
that are commonly used in residential dwellings. The heat exchange
core 10 is suitable for use in both of these applications, as it is
airtight and water tight even though, in an embodiment, adjacent
corrugated sheets need not be bonded to each other. In alternative
embodiments, the sheets may secured to each other or the frame in a
variety of ways, such as by any combination of ultrasonic or
thermal bonding, mechanical fasteners, adhesives or sealants.
[0044] It is contemplated that features disclosed in this
application, as well as those described in the above applications
incorporated by reference, can be mixed and matched to suit
particular circumstances. Various other modifications and changes
will be apparent to those of ordinary skill.
* * * * *