US20060096746A1

US20060096746A1 - Heat exchanger core with expanded metal spacer component

Info

Publication number: US20060096746A1
Application number: US11/260,322
Authority: US
Inventors: Benoit Arpin; Frédérick Bédard; Michel Julien; Pierre Nadeau
Original assignee: Venmar Ventilation ULC
Current assignee: Venmar Ventilation ULC
Priority date: 2004-11-09
Filing date: 2005-10-28
Publication date: 2006-05-11
Also published as: CA2487459A1

Abstract

A plate-type heat exchanger element for a plate-type air to air heat exchanger. The heat exchanger element comprises a heat exchange partition sheet and a spacer member comprising a corrugated mesh of expanded sheet metal. The corrugated mesh has an upstream side edge and a downstream side edge. The upstream side edge and the downstream side edge are folded over edges.

Description

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. Pat. 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 Ser. No. 10/160,370 published under no. 2002/0185266 and carrying a publication date of Dec. 12, 2002 (the entire contents of these patent documents are incorporated herein by reference). See also U.S. Pat. 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 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 transferring 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. Pat. 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.
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. Pat. 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. Pat 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 a heat 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 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 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 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).
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 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.
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 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 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 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. Pat. No. 4,051,898.
In drawings which illustrate example embodiments of the various aspects of the present invention:
FIG. 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;
FIG. 1 a schematically illustrates an enlarged partial top view of the top of a rectangular crest of the expanded metal sheet mesh section of FIG. 1 showing a jagged edge of an upstream side edge;
FIG. 2 schematically illustrates a stacked exchanger having partition sheets spaced apart by corrugated expanded metal sheet mesh sections as shown in FIG. 1, the corrugated expanded metal sheet mesh sections being shown in outline only;
FIG. 3 a 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;
FIG. 3 b 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;
FIG. 4 shows a cross section through the corrugated expanded metal sheet mesh section of FIG. 3 along the line 4-4 in FIG. 3 a;
FIG. 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 FIG. 3 a, the mesh members being only partially shown;
FIG. 6 shows a cross section through the plate-type heat exchanger element of FIG. 5 along the line 6-6 in FIG. 5;
FIG. 7 schematically illustrates a stacked exchanger of the present invention comprising a plurality of plate-type heat exchanger element as shown in FIG. 5, the corrugated expanded metal sheet mesh sections being shown in outline only;
FIG. 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
FIGS. 9 and 10 schematically illustrate a number of stage of the fabrication of the plate-type heat exchanger element of FIG. 5 using the corrugated expanded sheet metal mesh section of FIG. 3 a.
Referring to FIG. 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 FIG. 2. The edges 7, 9, 11 and 13 are not folded over edges and thus each present a jagged aspect as discussed herein; FIG. 1 a illustrates the jagged nature of these edges, the jagged edge being generally designated in FIG. 1 a by the reference numeral 15. Reference may also be made to FIG. 3 b, 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 FIG. 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 multi-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 designated by the reference numerals 25 a and 25 b; the arrow 25 a being indicative of airflow into the downstream side of the first passageway and the arrow 25 b 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 29 a and 29 b; the arrow 29 a being indicative of airflow into the downstream side of the second passageway and the arrow 29 b 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 FIG. 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 FIG. 3 a, 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 FIG. 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 of a stacked exchanger such as shown in FIG. 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 FIG. 3 b 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 FIGS. 3 a 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 FIG. 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 FIG. 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.
Referring to FIGS. 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 FIG. 3 a) 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.
Referring to now to FIG. 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 FIGS. 5 and 6) superposed on one another so as to form a multi-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 94 a and 94 b; the arrow 94 a being indicative of airflow into the downstream side of the first passageway and the arrow 94 b 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 98 a and 98 b; the arrow 98 a being indicative of airflow into the downstream side of the second passageway and the arrow 98 b 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 FIG. 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 FIGS. 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 FIG. 3 a); these sheet metal mesh elements thus have the structure as illustrated in FIGS. 3 a and 4. In the illustrated exchanger 86 the upstream and downstream sides of the corrugated sheet metal mesh elements 40 have folded over edges ( elements 58 and 60 in FIGS. 3 a and 5) in accordance with the present invention.
Turning to FIG. 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 FIG. 3 a). The 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 FIG. 5) will now be discussed by referring to FIGS. 9 and 10 as well as FIGS. 3 a, 5 and 6. Referring in particular to FIGS. 9 and 10, a corrugated sheet metal mesh element 40 (FIG. 3 a) is placed onto the surface of a rectangular heat transfer partition sheet 68 (FIG. 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 and 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 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 FIG. 6) which is the same height as the adjacent respective rectangular crest 42. Thus as may be seen form FIGS. 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 all 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 as described above.

Claims

1. A 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.

2. A plate-type heat exchanger as defined in claim 1 wherein said partition sheets are of material having heat conductivity and moisture permeability.

3. A plate-type heat exchanger as defined in claim 1 wherein said corrugated mesh is of aluminum.

4. A plate-type heat exchanger as defined in claim 2 wherein said partition sheets are of paper and said corrugated mesh is of aluminum.

5. 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.

6. A plate-type heat exchanger element as defined in claim 5 wherein said partition sheet is of material having heat conductivity and moisture permeability.

7. A plate-type heat exchanger element as defined in claim 5 wherein said corrugated mesh of aluminum.

8. A plate-type heat exchanger element as defined in claim 5 wherein said partition sheet is of paper and said corrugated mesh is of aluminum.

9. 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, 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 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.

10. A plate-type heat exchanger element as defined in claim 9 wherein said partition sheet is of material having heat conductivity and moisture permeability.

11. A plate-type heat exchanger element as defined in claim 9 wherein said corrugated mesh is of aluminum.

12. A plate-type heat exchanger element as defined in claim 9 wherein said partition sheet is of paper and said corrugated mesh is of aluminum.

13. 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

14. A spacer member as defined in claim 13 wherein said corrugated mesh is of aluminum.