Note: Descriptions are shown in the official language in which they were submitted.
CA 02487459 2004-11-09
TITLE: HEAT EXCHANGER CORE~WITH EXPANDED METAL
SPACER COMPONENT
The present invention relates to air to air heat exchangers for use in a
ventilation
system able to provide fresh air to an enclosure, such as for example, the
interior of
one or more rooms of a house or building. Thus, the invention is concerned
with a
heat exchanger which can exchange heat between the outgoing air discharged to
the
outside and the incoming air introduced from the outside of an enclosure to
thereby
recover the heat which otherwise is carried away by the outgoing air.
More particularly, the present invention relates to plate-type air to air heat
exchangers
which are capable of exchanging actual (i.e. sensible) heat or a combination
of actual
heat and latent heat (i.e. humidity) between outgoing air and incoming fresh
air in
relation to an enclosure. The following will, however, by way of example only,
discuss the invention in relation to the transfer of sensible heat and
humidity between
discharge air and fresh air.
Plate-type air to air heat exchangers are known; such exchangers are for
example
described in U.S. Patent nos. 4,022,050, 4,040,804, 4,051,898, 4, 377, 400,
4,434,835, 4,460,388, 4,848,450, 6,394,179, and 6,536,514 as well as U.S.
patent
application no. 10/160,370 published under no. 2002/0185266 and carrying a
publication date of December 12, 2002 (the entire contents of these patent
documents
are incorporated herein by reference). See also U.S. Patent nos. 3,931,854,
4,016,928, 4,966,231, 5,279,361, 5,474,639, and 6,032,730 (the entire contents
of these patent documents are also incorporated herein by reference).
Plate-type air to air heat exchangers generally comprise a plurality of
stacked
heat exchange partition sheets or plates. Each partition plate or sheet may
for
example be spaced apart from an adjacent partition sheet or plate by
respective
spacing apart means so as to thereby form a plurality of first and second
passageways
(e.g. alternating first and second passageways) for a first air stream and a
second air
stream to pass there through, respectively. This type of known exchanger also
comprises means for sealing two opposing sides of the first passageways
thereby
allowing the first air stream to pass there through in a first direction; and
additional
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means for sealing two opposing sides of said second passageways thereby
allowing
the second air stream to pass there through in a second direction.
Thus, a plate-type heat exchanger may create or define alternating flow
passageways
for the fresh air stream and exhaust air stream to pass there through. The
flow
passageways are typically either parallel or perpendicular to one another
(e.g. for
counter flow or for cross flow of air there through). For a cross flow heat
exchanger,
the alternating flow passages are generally perpendicular to one another.
However, if
the alternating flow passageways are parallel to one another and the air
streams flow
in the same direction, then the heat exchanger may be referred to as a co-flow
heat
exchanger. Additionally, if the alternating flow passageways are parallel to
one
another but the air streams flow in opposite directions, then the heat
exchanger may
be referred to as a counter flow heat exchanger.
In any event regardless of the direction of the air flow patterns, as the
outgoing and
incoming air streams pass through respective passageways and along opposite
sides of
the heat exchange plates or sheets, the heat or energy in one air stream is
transferred
to the other air stream. Depending upon the material of the plates or sheets,
the plates
or sheets can transfer sensible heat or both sensible and latent heat.
Specifically, the
plates or sheets may be made of a material that is only capable of
transferring sensible
heat. On the other hand, the plates or sheets may be made of a material that
is capable
of transfernng latent heat, as well as sensible heat. For example, metal
plates or
sheets, such as aluminum plates, absorb a portion of the thermal energy in one
air
stream and transfer such energy to the other air stream without allowing any
moisture
to pass there through. Alternatively, the plates or sheets may be made of
paper
capable of transferring sensible heat as well as latent heat (i.e. moisture)
between air
streams. Such paper materials suitable for such exchanger plates or sheets are
for
example described in U.S. patent nos. 4,040,804 and 4,051,898; the paper may
for
example be Japanese paper.
It is also known to use a corrugated mesh of expanded sheet metal as a spacer
member
to space apart adjacent exchanger plates or sheets.
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Expanded metal is a well-known commercial item and may, for example, be
fabricated from a roll of sheet metal (e.g. metal foil) by cutting a plurality
of rows of
slits in the sheet metal stock, the slits of each row of slits being offset
from those of
the adjacent rows by half the distance between slits, and then exerting a
tensile stress
across the sheet metal stock perpendicular to the slits therein to expand the
metal by
opening the slits to create the plurality of openings or apertures therein,
i.e. to create
an expanded metal sheet mesh. See for example U.S. patent nos. 4,016,928 and
6,629,016. Expanded metal may be formed from many metals, e.g. aluminum and
copper. See also U.S. patent nos. 4,315,356, 4,526,347, 4,921,118, and
5,302,466, (the entire contents of these patent documents are incorporated
herein by
reference).
A roll of expanded sheet metal mesh may, for example, be cut into
appropriately sized
essentially flat or planar sheet metal mesh elements. These sheet metal mesh
elements may be passed through the nip of a pair of opposed rollers having
alternating male and female elements which are configured to provide the sheet
metal
mesh elements with a desired or predetermined corrugated configuration
suitable for
its use as a spacer member, e.g. a corrugated configuration whereby the mesh
element
has a cross section which resembles a square wave.
However, the process of expanding a metal sheet and/or cutting the expanded
metal
sheet to size (i.e. rectangular sheets) for use as a spacer member results in
a sheet
metal mesh element having opposed peripheral side edges which have a jagged
shape
or contour; such contour presents a handling hazard since the contour may
effectively
act as a sharp cutting edge which may result in injury to person handling or
manipulating the sheet metal mesh.
Thus, for example, it is known to use such a corrugated mesh of expanded sheet
metal
as a spacer member for a plate-type air to air heat exchanger as described
above.
However the incorporation of such sheet metal mesh into wheat exchanger
provides
an exchanger wherein jagged edges are exposed on the upstream and downstream
sides of the above mentioned first and second passageways. Such exposed jagged
edges may as mentioned present a safety hazard to a person manually handling
such
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CA 02487459 2004-11-09
an exchanger, i.e. if improperly handled such exchanger may cause hand injury
for
example.
Thus it would be advantageous to have available corrugated expanded sheet
metal
mesh which avoids or attenuates such jagged edge contour. It would further be
advantageous to have an exchanger wherein the upstream and downstream edges of
a
spacer member comprising a corrugated mesh of expanded sheet metal which
avoids
or attenuates such jagged edge contour. It would further be advantageous to
have a
method for the fabrication of a spacer member as well as a plate-type heat
exchanger
element for a plate-type air to air heat exchanger comprising a corrugated
mesh of
expanded sheet metal which avoids or attenuates such jagged edge contour.
STATEMENT OF INVENTION
Thus the present invention in an aspect provides a spacer member for a plate-
type air
to air heat exchanger, said spacer member comprising a corrugated mesh of
expanded
sheet metal having an upstream side edge and a downstream side edge
characterized in that said upstream side edge and said downstream side edge
are
folded over edges.
The present invention in another aspect provides a plate-type heat exchanger
element
for a plate-type air to air heat exchanger, said heat exchanger element
comprising a
heat exchange partition sheet and a spacer member, said spacer member
comprising a
corrugated mesh of expanded sheet metal, said corrugated mesh having an
upstream
side edge and a downstream side edge
characterized in that said upstream side edge and said downstream side edge
are
folded- over edges.
The present invention in particular provides a plate-type heat exchanger
element for a
plate-type air to air heat exchanger, said heat exchanger element comprising a
heat
exchange partition sheet and a spacer member, said spacer member comprising a
corrugated mesh of expanded sheet metal, said corrugated mesh having an
upstream
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CA 02487459 2004-11-09
side edge, a downstream side edge and a pair of opposed wall side edges
connecting
said upstream side edge to said downstream side edge,
characterized in that said upstream side edge and said downstream side edge
are
S folded over edges
and
said heat exchange partition sheet is attached to said corrugated mesh at each
of said
wall side edges so as to define an exchanger air flow barrier element.
The present invention in a further aspect provides plate-type air to air heat
exchanger,
comprising
a plurality of stacked heat exchange partition sheets, each partition sheet
being spaced apart from an adjacent partition sheet by respective spacing
apart means
so as to thereby form a plurality of first and second passageways for a first
air stream
and a second air stream to pass there through, respectively;
means for sealing two opposing sides of said first passageways thereby
allowing the first air stream to pass there through in a first direction;
means for sealing two opposing sides of said second passageways thereby
allowing the second air stream to pass there through in a second direction
and
wherein said spacing apart means for each of said first and second passageways
comprises a corrugated mesh of expanded sheet metal having an upstream side
edge
and a downstream side edge
characterized in that said upstream side edge and said downstream side edge
are
folded over edges.
It is to be understood herein that the expressions 'folded over edge', 'folded
over
edges' and the like refers to an edge which, relative to the initial jagged
edge, is a
(relatively) dull edge.
In accordance with the present invention a partition sheet may be of material
having
heat conductivity and moisture permeability; a partition sheet may for example
be of
paper (i.e. of heat and moisture permeable paper).
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In accordance with the present invention a corrugated mesh may be of expanded
(sheet) aluminum.
In accordance with the present invention a plate-type air to air heat
exchanger may
take on a quadrilateral configuration and in particular a rectangular
configuration (e.g.
the partition sheets as well as the spacer members may have a rectangular
configuration).
In accordance with the present invention, a spacer member may, for example, be
fabricated by exploiting any known, desired or appropriate, sheet metal
expansion
technique to provide a mesh of expanded sheet metal (sometimes referred to
herein
simply as sheet metal mesh) having opposed jagged or sharp edges; the sheet
metal
mesh may, for example, be in the form of a roll thereof or an elongated sheet
thereof.
Such initial mesh of expanded sheet metal may for example be a mesh of
expanded
aluminum foil.
An initial mesh of expanded sheet metal may be subjected to a folding
treatment stage
at an edge folding station (of any suitable or desired, configuration) which
is able to
impart opposed folded over edges to a sheet metal mesh, i.e. provide opposed
folded
edges having a dulled aspect relative to any initial jagged edges. At such
edge
folding station, opposed edge margin portions of the sheet metal mesh are each
folded over themselves so as to form or define a respective folded over edge;
each
opposed edge margin portion comprises a longitudinally extending edge portion
of a
respective jagged or sharp edge. The edge folding station may if desired be a
manual
folding station wherein folding is accomplished manually or by hand.
Preferably
however the folding station is a mechanical edge folding station.
The edge folding station may, for example, comprise any suitable means for
progressively moving (i.e. feeding) a mesh of expanded sheet metal through a
folding
apparatus; it is to be understood herein that movement of the mesh in an
upstream
direction means movement of the mesh through the folding station. The folding
apparatus may, for example, comprise two spaced apart folding members disposed
for
folding engagement with a respective opposed edge margin portion of the sheet
metal
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CA 02487459 2004-11-09
mesh. In this manner, opposed edges of the sheet metal mesh may be more or
less
simultaneously folded over as the folding members are disposed directly
opposite to
each other. Alternatively, the folded over edges may be obtained by folding
over one
edge followed by folding over of the other edge, i.e. the folding members are
offset
relative to each other.
In any event, each folding member may comprise or take the form of a guide
flange
having a guide surface which initially tapers upwardly in the upstream
direction, then
inwardly over the metal sheet mesh and finally downwardly towards the metal
sheet
mesh until the guide surface is essentially parallel to the opposed surface of
the sheet
metal mesh. In other words a folding member may have a guiding type surface
which
is able to engage a respective edge margin portion of the sheet metal mesh so
as to
effect a gradual and continuous displacement (i.e. curling over) of a
respective margin
portion of the sheet metal mesh upwardly and eventually over the adjacent
portion of
the sheet mesh until the margin portion is folded over the sheet metal mesh as
desired. Preferably, the spacing between the upper parallel portion of the
guide
surface and the sheet metal mesh is such as to provide a permanent crimped
edge.
The folding members may be considered as each being one-half of a funnel the
purpose of which is to fold over a respective edge margin portion.
If desired or necessary the obtained sheet metal mesh with opposed folded
edges may
then be fed through the nip of a pair of opposed compression rollers in order
to not
only consolidate the folds but if so desired to reduce the thickness of the
sheet metal
mesh.
If the sheet metal mesh with opposed folded edges is obtained in the form of a
roll or
as an elongated sheet, the sheet metal mesh may as desired or necessary be
passed
through a cutting station wherein a guillotine type cutter may, for example
cut the
sheet metal mesh, transversely (e.g. perpendicular ) to the opposed folded
edges, into
smaller desired parallelogram forms (e.g. a rectangular form such as for
example a
square) or any other four sided or quadrilateral type forms as desired or
needed. The
obtained sheet metal mesh elements with opposed folded edges will in any event
have
opposed major sides which present a generally flat or planar aspect.
CA 02487459 2004-11-09
On the other hand, the edges of the sheet metal mesh elements formed by the
cutting
process may give rise to a further pair of jagged edges as described herein,
i.e. give
rise to a sheet metal mesh element with a pair of opposed folded edges and a
pair of
opposed jagged edges. These further jagged edges may as desired or necessary
be
subjected to a folding process the same as or analogous to that described
above.
Alternatively, these jagged edges may, for example, be covered by the heat
transfer
partition sheet as shall be described below.
An obtained metal sheet mesh element with opposed folded edges may, for
example,
be fed, folded edge first, through a corrugation station so as to provide the
sheet metal
mesh with corrugations which extend from one folded edge to the other folded
edge;
the folded edges thus being able to take on the role of an upstream or
downstream
edge as described herein.. The corrugation station may for example comprise a
pair
of compression rollers. The compression rollers may each have a plurality of
female
and male members which are able to mate with the corresponding male or female
members of the opposed compression roller. The compression rollers are
configured
and disposed so as to be able to impart to the sheet metal mesh, passing
through the
nip, defined by compression rollers, a desired corrugated configuration (e.g.
a square
wave like cross sectional shape, a sinusoidal wave like cross sectional shape,
a saw
tooth wave like cross sectional shape, and the like). The obtained corrugated
sheet
metal mesh may then be used as a spacer member to form, along with a heat
transfer
partition sheet, a plate-type heat exchanger element for a plate-type air to
air heat
exchanger.
A corrugated sheet metal mesh element (i.e. expanded aluminum foil) with
opposed
folded edges and opposed jagged edges may, for example, be of rectangular
form, i.e.
rectangular when viewed from above or below. The sheet metal mesh may, for
example, be corrugated such that the jagged side edges are each defined by a
respective marginal edge portion of the sheet metal mesh element wherein the
marginal edge portions more or less reflect the planes of the initial major
sides of the
un-corrugated sheet metal mesh. In this case a square crest of the corrugated
sheet
metal mesh is disposed immediately adjacent to each marginal edge portion. The
corrugations of the corrugated sheet metal mesh element may, for example, when
the
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CA 02487459 2004-11-09
mesh is viewed in cross section, also have a rectangular (e.g. square) wave
like
presentation, i.e. have rectangular crests and valleys of the same height and
depth.
A rectangular plate type heat exchanger element may, for example, be
fabricated by
placing a rectangular (e.g. square) corrugated sheet metal mesh element (as
described
immediately above) onto the surface of a rectangular heat transfer partition
sheet
which is sized so that the mesh and partition are able to be disposed edge to
edge
fashion. The folded over edges of the sheet metal mesh and the adjacent edges
of the
underlying partition sheet may be more or less coterminous. On the other hand,
the
partition sheet may also be sized or dimensioned such that the marginal edge
portions
of the partition sheet which are adjacent to the jagged edges of the sheet
metal mesh
element remain uncovered by respective jagged edges of the sheet metal mesh,
i.e. the
jagged edges of the sheet metal mesh are inwardly offset with respect to the
adjacent
marginal edge portions of the partition sheet so as to leave these edges of
the partition
sheet uncovered. The jagged edges may be sufficiently offset such that the
uncovered edge portions of the underlying partition sheet may be folded over
the
jagged edges so as to function as or be part of a side wall sealing means as
shall be
discussed below.
Once the rectangular corrugated sheet metal mesh element is suitably disposed
on top
of the underlying partition sheet (e.g. of paper), a bead of a hot
thermoplastic adhesive
(e.g. a hot melt glue or a similar or analogous type thermoplastic adhesive)
may, for
example, be applied to the upper surface of each of the above mentioned sheet
metal
mesh marginal edge portions in an elongated longitudinally extending bead
extending
from one folded over edge to the other folded over edge. The bead may be
applied to
the mesh marginal edges so as to more or less match the height of the adjacent
square
crest of the sheet metal mesh. While each of the adhesive beads is still soft,
each of
the adjacent uncovered edge portions of the partition sheet may be folded over
the
adhesive bead so as to be fixed thereby to the expanded metal sheet mesh (e.g.
aluminum mesh).
However, it is to be noted that the width of the uncovered edge portions of
the
partition sheet, the height of the adjacent rectangular crests and the
thickness of the
adhesive bead may, in this case, be predetermined such that once the uncovered
edge
CA 02487459 2004-11-09
portions of the partition sheet cover and are fixed to the hot melt adhesive,
the so
attached uncovered edge portions (once the adhesive solidifies) extend at
least to a
respective rectangular crest so as to define a side air flow barrier (e.g. a
side wall
impermeable to air) which is the same height as the adjacent rectangular
crest. For
example, the uncovered edge portions of the partition sheet, when folded over,
may
only extend to the top of the adjacent rectangular crest so as to leave all of
the
rectangular crests of the corrugate sheet metal mesh element uncovered and
exposed.
On the other hand, an axis perpendicular to both of the uncovered folded over
edges
may be considered to be an air flow axis, i.e. an axis along which air will be
free to
flow from one (upstream) folded over edge to the other (downstream) folded
over
edge. It is nevertheless also to be understood herein that if it is desired to
provide or
define an above described side air flow barrier any other manner of fixing the
uncovered edge portions of the partition sheet may be utilized keeping in mind
the
intended purpose of the barrier; e.g. the partition sheet may be sized so as
to be able
extend over all of the crests, i.e. the partition sheet can be wrapped fully
around the
sheet metal mesh leaving the above mentioned air flow axis.
A rectangular plate type heat exchanger element as described above may, for
example, be used to construct a plate type air heat exchanger.
Thus, for example, a cross flow, plate-type air to air heat exchanger may be
formed by
stacking a plurality of the above described rectangular plate type heat
exchanger
elements one on top of the other such that the major faces of the exchanger
elements
abut each other; i.e. one major face of an exchanger element being defined by
the
exposed rectangular crests thereof and the other by the underlying partition
sheet.
The rectangular plate type heat exchanger elements may be stacked such that
the
partition sheet of an exchanger element overlying an adjacent like exchanger
element'
abuts exposed rectangular crests of the corrugated sheet metal mesh element of
the
underlying exchanger element. The rectangular plate type heat exchanger
elements
may also be stacked such that adjacent exchanger elements are oriented such
that the
air flow axis of one exchanger element is perpendicular to the air flow axis
of the
other adjacent exchanger element. In this manner each side wall of the
exchanger
will comprise a plurality of alternating air openings and air flow barrier
elements (as
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CA 02487459 2004-11-09
alluded to above), so as to thereby form a plurality of first and second
passageways
for a first air stream and a second air stream to pass there through,
respectively.
As may be surmised each partition sheet is thus spaced apart from an adjacent
partition sheet by an intermediate spacing apart means defined by a corrugated
mesh
of expanded sheet metal; as may also be surmised respective air flow barriers
define
means for sealing two opposing sides of the first and second passageways
thereby
allowing the first and second air streams to pass there through in respective
first and
second directions. As may also be understood each of the first and second
passageways comprises an upstream folded over edge and a downstream folded
over
edge as described herein.
The elements of a stacked exchanger as described above may be held in place in
any
suitable manner; see for example Canadian patent nos. 2,030,577 and 2,122,392
(the
entire contents of these Canadian patent are incorporated herein by
reference). The
elements may for example be held together by any (known) type of casing frame
which allows for air access to the air passageways. For example, the corners
of the
exchanger may abut correspondingly shaped elongated angle elements or members
which are suitably fixed to one another; alternatively, elongated angel
elements may
be suitably fixed to top and/or bottom cover plate members which abut the
major face
of an adjacent exchanger element; please see for example U.S. patent no.
4,051,898.
In drawings which illustrate example embodiments of the various aspects of the
present invention:
Figure 1 schematically illustrates a corrugated expanded metal sheet mesh
section
having rectangular crests and valleys of the same height and depth but without
folded
over upstream and downstream edges, the mesh members being only partially
shown;
Figure la schematically illustrates an enlarged partial top view of the top of
a
rectangular crest of the expanded metal sheet mesh section of figure 1 showing
a
jagged edge of an upstream side edge;
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CA 02487459 2004-11-09
Figure 2 schematically illustrates a stacked exchanger having partition sheets
spaced
apart by corrugated expanded metal sheet mesh sections as shown in Figure 1,
the
corrugated expanded metal sheet mesh sections being shown in outline only;
Figure 3a schematically illustrates a corrugated expanded metal sheet metal
section
having rectangular crests and valleys of the same height and depth but with
folded
over upstream and downstream edges in accordance with the present invention,
the
mesh members being only partially shown;
Figure 3b is a photograph of a piece of expanded metal sheet mesh showing one
side
edge which is a folded over side edge, the remaining three side reflecting
jagged side
edges;
Figure 4 shows a cross section through the corrugated expanded metal sheet
mesh
section of f gore 3 along the line A-A in Figure 3a;
Figure 5 schematically illustrates a plate-type heat exchanger element, in
accordance
with the present invention, for a plate-type air to air heat exchanger, said
heat
exchanger element comprising a spacer member comprising a corrugated expanded
sheet metal mesh section as shown in Figure 3a, the mesh members being only
partially shown;
Figure 6 shows a cross section through the plate-type heat exchanger element
of
Figure 5 along the line B-B in Figure 5;
Figure 7 schematically illustrates a stacked exchanger of the present
invention
comprising a plurality of plate-type heat exchanger element as shown in Figure
5, the
corrugated expanded metal sheet mesh sections being shown in outline only;
Figure 8 schematically illustrates an expanded sheet metal mesh in an
initially
essentially flat or planar form, the mesh members being only partially shown,
in the
process of having opposed side edges being folded over onto themselves;
and
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CA 02487459 2004-11-09
Figure 9 and 10 schematically illustrate a number of stage of the fabrication
of the
plate-type heat exchanger element of Figure 5 using the corrugated expanded
sheet
metal mesh section of Figure 3a.
Refernng to Figure 1, this figure illustrates a top perspective view of a
rectangular
corrugated sheet metal mesh element 1; the sheet metal mesh element 1 is an
expanded sheet metal as described herein. The corrugations of the corrugated
sheet
metal mesh element 1 take the aspect of rectangular crests (some of which are
generally designated by the reference numeral 3) and rectangular valleys (some
of
which are generally designated by the reference numeral 5) of the same height
and
depth.
The sheet metal mesh element 1 has an upstream edge 7 and an opposed
downstream
edge 9 as well as two interconnecting side edges 11 and 13; i.e. these
upstream and
downstream edges 7 and 9 are intended to be respectively disposed on the
upstream
and downstream sides of the first and second passageways of a stacked
exchanger
such as shown in Figure 2. The edges 7, 9, 11 and 13 are not folded over edges
and
thus each present a jagged aspect as discussed herein; Figure la illustrates
the jagged
nature of these edges, the jagged edge being generally designated in Figure l
a by the
reference numeral 15. Reference may also be made to Figure 3b, which is a
photo of
a piece of mesh of expanded sheet metal (i.e. aluminum) showing by way of
example
such jagged edges along three sides thereof.
Referring now to Figure 2, there is illustrated a plate-type air to air heat
exchanger 17.
The exchanger 17 comprises a stack of heat-and-moisture exchange elements
superposed on one another so as to form a mufti-layer cross flow heat-and-
moisture
exchanger. In the arrangement as shown, the exchanger has a plurality of first
air
passageways (generally designated by the reference numeral 19 for a first air
stream.
The exchanger also has a plurality of second air passageways (generally
designated by
the reference numeral 21 for a second air stream. A plurality of pairs of
opposed side
wall barrier elements (one element of each pair being generally designated by
the
reference numeral 23) help define the first passageways 19 thereby allowing
the first
air stream to pass through the first passageways in a first airflow direction
generally
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CA 02487459 2004-11-09
designated by the reference numerals 25a and 25b; the arrow 25a being
indicative of
airflow into the downstream side of the first passageway and the arrow 25b
being
indicative of airflow from the upstream side of the first passageway. A
further
plurality of pairs of opposed side wall barrier elements (one element of each
pair
being generally designated by the reference numeral 27) help define the second
passageways 21 thereby allowing the second air stream to pass through the
second
passageways in a second air flow direction generally designated by the
reference
numeral 29a and 29b;the arrow 29a being indicative of airflow into the
downstream
side of the second passageway and the arrow 29b being indicative of airflow
from the
upstream side of the second passageway. As may be appreciated the two air flow
directions are in crossing perpendicular relationship with respect to each.
Each of the first and second passageways are also defined by heat exchange
partition
sheets. The heat exchange partition sheets are spaced apart by a plurality of
rectangular corrugated sheet metal mesh elements; these sheet metal mesh
elements
have the structure as illustrated in figure 1. In the illustrated exchanger 17
the jagged
edges of the upstream and downstream sides of the corrugated sheet metal mesh
elements extend out of the respective upstream and downstream sides of the
first and
second passageways such that the jagged edges are exposed (not shown) and may
inflict injury to a person handling or manipulating the exchanger 17 if the
exchanger
17 is not carefully handled.
Referring to Figure 3a, this figure illustrates a top perspective view of a
rectangular
corrugated sheet metal mesh element 40 in accordance with the present
invention; the
sheet metal mesh element 40 is also an expanded sheet metal as described
herein.
Referring also to Figure 4, the corrugations of the corrugated sheet metal
mesh
element 40 also take the aspect of rectangular crests (some of which are
generally
designated by the reference numeral 42) and rectangular valleys (some of which
are
generally designated by the reference numeral 44) of the same height and
depth.
The sheet metal mesh element 40 has an upstream edge 46 and an opposed
downstream edge 48 as well as two interconnecting side edges 50 and 52; i.e.
these
upstream and downstream edges 46 and 48 are also intended to be respectively
disposed on the upstream and downstream sides of the first and second
passageways
CA 02487459 2004-11-09
of a stacked exchanger such as shown in Figure 7. The edges 46 and 48 are
folded
over edges of metal mesh as contemplated by the present invention; these
folded over
edges are each shown as an edge band generally designated respectively by the
reference numerals 58 and 60. The photo of Figure 3b illustrates an example
folded
over edge of a piece of mesh of expanded sheet metal (i.e. aluminum) showing
one
folded edge along one side thereof and jagged edges along the three remaining
sides.
The folded over edges 46 and 48 also lend a reinforced nature to the upstream
and
downstream side edges of the corrugated sheet metal mesh element 40, i.e.
being
thicker than the rest of the body of the corrugated sheet metal mesh element
40.
Turning again to Figures 3a and 4, the interconnecting edges 50 and 52, on the
other
hand, are not folded over edges and thus each present a jagged aspect as
discussed
herein, i.e. edge 50 and 52 are jagged edges. These jagged edges 50 and 52 are
each
defined by a respective marginal edge portion of the sheet metal mesh element
40; the
marginal edge portions are generally designated by respective reference
numerals 62
and 64 (see for example Figure 4). The marginal edge portions 62 and 64 more
or
less reflect the planes of the initial major sides of the un-corrugated sheet
metal mesh.
As may be seen from Figure 4, a square crest 42 of the corrugated sheet metal
mesh
element 40 is disposed immediately adjacent to each marginal edge portion 62
and 64.
Refernng to Figures 5 and 6, these figures illustrates an example a
rectangular plate
type heat exchanger element 67 comprising a rectangular (e.g. square)
corrugated
sheet metal mesh element 40 (as shown in Figure 3a) attached along the
marginal
edge portions 62 and 64 thereof to a rectangular heat transfer partition sheet
68 by
respective adhesive beads 70 and 72. The beads 70 and 72 are covered by edge
portions of the partition sheet 68 which extend up to the top of respective
adjacent
rectangular crests 42 so as to leave all of the rectangular crests of the
corrugate sheet
metal mesh element uncovered and exposed as well as to define side air flow
barriers
(respectively indicated by the reference numerals 76 and 78) which are the
same
height as the adjacent rectangular crests 42. The axis designated by the
reference
numeral 82 is perpendicular to both of the uncovered folded over edges may be
considered to be an air flow axis, i.e. an axis along which air will be free
to flow from
one (upstream) folded over edge to the other (downstream) folded over edge.
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CA 02487459 2004-11-09
Referring to now to Figure 7, there is illustrated a plate-type air to air
heat exchanger
86 in accordance with the present invention. The exchanger 86 comprises a
stack of
heat-and-moisture exchange elements 67 (as illustrated in Figures 5 and 6)
superposed
on one another so as to form a mufti-layer cross flow heat-and-moisture
exchanger. In
the arrangement as shown, the exchanger has a plurality of first air
passageways
(generally designated by the reference numeral 88 for a first air stream. The
exchanger also has a plurality of second air passageways (generally designated
by the
reference numeral 90 for a second air stream. A plurality of the pairs of
opposed side
wall barrier elements 76 and 78 (only element 76 is seen) help define the
first
passageways 88 thereby allowing the first air stream to pass through the first
passageways in a first airflow direction generally designated by the reference
numerals 94a and 94b; the arrow 94a being indicative of airflow into the
downstream
side of the first passageway and the arrow 94b being indicative of airflow
from the
upstream side of the first passageway. A further plurality of pairs of opposed
side
wall barrier elements 76 and 78 (only element 78 is seen) help define the
second
passageways 90 thereby allowing the second air stream to pass through the
second
passageways in a second air flow direction generally designated by the
reference
numeral 98a and 98b;the arrow 98a being indicative of airflow into the
downstream
side of the second passageway and the arrow 98b being indicative of airflow
from the
upstream side of the second passageway. As may be appreciated the two air flow
directions are in crossing perpendicular relationship with respect to each,
i.e. the air
flow axis (element 82 in Figure 5) of one heat-and-moisture exchange elements
40 is
perpendicular to an adjacent of heat-and-moisture exchange elements 40.
Each of the first and second passageways are 88 and 90 also defined by heat
exchange partition sheets (element 68 in Figures 5 and 6). The heat exchange
partition sheets 68 are, however, spaced apart by a plurality of rectangular
corrugated
sheet metal mesh elements (element 40 in Figure 3a); these sheet metal mesh
elements
thus have the structure as illustrated in Figures 3a and 4. In the illustrated
exchanger
86 the upstream and downstream sides of the corrugated sheet metal mesh
elements
have folded over edges (elements 58 and 60 in Figures 3a and 5) in accordance
with the present invention.
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CA 02487459 2004-11-09
Turning to Figure 8, this figure illustrates an expanded sheet metal mesh 100
in an
initially essentially flat or planar form, in the process of having opposed
side edges
designated generally by respective reference numerals 102 and 104 being folded
over
onto themselves at an edge folding station. The folding station comprises any
suitable
means (not shown) for .progressively moving (i.e. feeding) the mesh 100
through a
folding apparatus or system.
The folding apparatus comprises two spaced apart folding members 106 and 108
fixed
in place by any suitable means relative to the moving mesh 100. As may be seen
the
folding members 106 and 108 are disposed for folding engagement with edge
portions
of a respective opposed edge 102 and 104 of the sheet metal mesh 100. In this
manner, the opposed edges 102 and 104 of the sheet metal mesh 100 may be more
or
less simultaneously folded over since the folding members 106 and 108 are
disposed
directly opposite to each other.
.
Each folding member 106 and 108 takes the form of a guide flange having a
guide
surface which initially tapers upwardly in the upstream direction (indicated
by the
arrow 110) , then inwardly over the metal sheet mesh and finally downwardly
towards
the metal sheet mesh until the guide surface is essentially parallel to the
opposed
surface of the sheet metal mesh 100. In other words a folding member 106 or
108
may have a guiding type surface which is able to engage a respective edge
margin
portion of edge 102 or 104 of the sheet metal mesh 100 so as to effect a
gradual and
continuous displacement (i.e. curling over) of a respective margin portion of
the sheet
metal mesh 100 upwardly and eventually over the adjacent portion of the sheet
metal
mesh 100 until the margin portion is folded over the sheet metal mesh as
desired, e.g.
to form edge portion 58 or 60 (see figure 3a) . T he spacing between the upper
parallel portion of the guide surface and the sheet metal mesh 100 is such as
to
provide a permanent crimped edge. The folding members may be considered as
each
being one-half of a funnel the purpose of which is to fold over a respective
edge
margin portion.
The fabrication of a rectangular plate type heat exchanger element (designated
by
reference numeral 67 in figure 5) will now be discussed by referring to
Figures 9 and
IO as well as Figures 3a, 5 and 6. Referring in particular to Figures 9 and
10, a
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CA 02487459 2004-11-09
corrugated sheet metal mesh element 40 (Figure 3a) is placed onto the surface
of a
rectangular heat transfer partition sheet 68 (Figure 5). As may be seen heat
transfer
partition sheet 68 is sized so that the sheet metal mesh element 40 and
partition sheet
68 are able to be disposed edge to edge fashion. The edges 46 and 48 of the
sheet
metal mesh 40 and the adjacent edges of the underlying partition sheet 68 are
more or
less coterminous. On the other hand, the partition sheet 68 is sized or
dimensioned
such that the marginal edge portions 110 a,nd 112 of the partition sheet 68
are offset
with respect to the marginal edge portions 62 and 64 of the sheet metal mesh
element
40 such that the marginal edge portions 110 and 112 remain uncovered, i.e. the
jagged
edges 50 and 52 of the sheet metal mesh element 40 are inwardly offset with
respect
to the adjacent marginal edge portions 110 and 112 of the partition sheet 68.
The
jagged edges 50 and 52 are sufficiently offset such that the uncovered edge
portions
110 and 112 of the underlying partition sheet may be folded over the jagged
edges 50
and 52 so as to function as or be part of a side wall sealing means as shall
be
discussed below.
Once the rectangular corrugated sheet metal mesh element 40 is suitably
disposed on
top of the underlying partition sheet (e.g. of paper) as discussed above, a
bead of a hot
thermoplastic adhesive (e.g. a hot melt glue or a similar or analogous type
thermoplastic adhesive) is applied from an applicator (designated by the
reference
numeral 18) to the upper surface of each of the above mentioned sheet metal
mesh
marginal edge portions 62 and 64 in an elongated longitudinally extending bead
( 120
and 122) extending from folded over edge 46 to the other folded over edge 48.
The
beads 120 and 122 are applied to the marginal edges 62 and 64 so as to more or
less
match the height of the adjacent square crests 42 of the sheet metal mesh
element 40.
While each of the adhesive beads 120 and 122 is still soft, each of the
adjacent
uncovered edge portions 110 and 112 of the partition sheet 68 may be folded
over a
respective adhesive bead 120 and 122 so as to be fixed thereby to the expanded
metal
sheet mesh 40 (e.g. aluminum mesh).
However, it is to be noted that the width of the uncovered edge portions 110
and 112
of the partition sheet, the height of the adjacent rectangular crests and the
thickness of
the adhesive bead is such that once the uncovered edge portions 110 and 112 of
the
partition sheet 68 cover and are fixed to the hot melt adhesive, the so
attached
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CA 02487459 2004-11-09
uncovered edge portions (once the adhesive solidifies) extend to a respective
rectangular crest 42 so as to define a side air flow barrier 76 and 78 (see
Figure 6)
which is the same height as the adjacent respective rectangular crest 42. Thus
as may
be seen form figures 5 and 6 the uncovered edge portions 110 and 112 of the
partition
sheet, when folded over, only extend to the top of the adjacent rectangular
crest 42 so
as to leave aII of the rectangular crests of the corrugate sheet metal mesh
element 40
uncovered and exposed.
A rectangular plate type heat exchanger element as described above may be used
to
construct a plate type air heat exchanger also a~ described above.
