HEAT EXCHANGER

ECHANGEUR DE CHALEUR

English Abstract

A heat exchanger for exchanging heat between a cooler first air flow and a
warmer second air
flow is disclosed. The heat exchanger comprises a heat exchanger unit having a
housing
containing a plurality of heat exchanger plates stacked together to form a
stack. Each heat
exchanger plate has four corners and an aperture located adjacent each corner,
the heat
exchanger plates being dimensioned and configured such that the apertures of
the heat exchanger
plates overlap to form a first, second, third and fourth air passageways in
the stack. The heat
exchanger plates are further configured to form an alternating series of first
and second flat
parallel air chambers in the stack, the first set of air chambers being
continuous with the first and
second air passages such that air can pass between the first and second air
passages through the
first set of air chambers, the second set of air chambers being continuous
with the third and
fourth air passageways such that air can pass between the third and fourth air
passageways
through the second set of air chambers. The stack of heat exchanger plates are
further
configured such that the first and second set or air chambers are
substantially air tight such that
air does not leak between the first and second set of air chambers. The heat
exchanger unit has a
first and second side, the first, second, third and fourth air passageways
each having a first end
open to the first side of the heat exchanger unit at a first port and an
opposite second end opened
to the second side of the heat exchanger unit at a second port. The stack is
further adapted such
that each port may be selectively plugged by a plug member, the heat exchanger
unit having four
plug members, each plug member plugging one end of each air passageway.
Finally, the first,
second, third and fourth air conduits, are each operatively coupled to one of
the air passageways,
the air conduits carrying the first and second air flows.

French Abstract

La présente invention concerne un échangeur de chaleur grâce auquel un échange de chaleur s'effectue entre le dispositif de refroidissement du premier débit d'air et le dispositif de réchauffement du deuxième débit d'air. L'échangeur de chaleur est constitué d'une unité d'échangeur de chaleur comportant un boîtier à l'intérieur duquel se trouve plusieurs plaques déposées les unes sur les autres afin de former un empilement. Chaque plaque de l'échangeur de chaleur comporte quatre coins et une ouverture située près de chacun de ces coins, les plaques de l'échangeur de chaleur étant d'une dimension et d'une configuration telles que les ouvertures des plaques se chevauchent pour former une première, une deuxième, une troisième et une quatrième voie de passage de l'air dans l'empilement des plaques. De plus, les plaques de l'échangeur de chaleur sont configurées de manière à former des séries alternatives de premier et de deuxième réservoir d'air parallèle et plat dans l'empilement, la première série de réservoirs d'air se trouvant à la suite de la première et de la deuxième voie de passage de l'air, de telle sorte que l'air peut circuler entre la première et la deuxième voie de passage à travers la première série de réservoirs d'air; la deuxième série de réservoirs d'air se trouvant à la suite des troisième et quatrième voies de passage de l'air, de telle sorte que l'air peut circuler entre la troisième et la quatrième voie de passage de l'air à travers la deuxième série de réservoirs d'air. L'empilement des plaques de l'échangeur d'air est, de plus, configuré de manière à ce que la première et la deuxième série de réservoirs d'air soient très étanches à l'air afin que l'air ne puisse pas circuler entre la première et la deuxième série de réservoirs d'air. L'unité d'échangeur d'air comporte un premier et un deuxième côté, la première, la deuxième, la troisième et la quatrième voie de passage de l'air possédant chacune une première extrémité ouverte sur le premier côté de l'unité d'échangeur d'air à un premier orifice et une deuxième extrémité opposée ouverte sur le deuxième côté de l'unité d'échangeur d'air à un deuxième orifice. L'empilement est ajusté de telle sorte que chaque orifice peut être bouché par un obturateur, de manière sélective. L'unité d'échangeur d'air comprend quatre obturateurs, chaque obturateur pouvant boucher une des extrémités de chaque voie de linepassage de l'air. Finalement, le premier, le deuxième, le troisième et le quatrième conduit d'air sont chacun accouplés, de manière à fonctionner, à une des voies de passage de l'air, les conduits d'air assurant le premier et le deuxième débit d'air.

Claims

WHAT IS CLAIMED IS:
1. A heat exchanger for exchanging heat between a first cool air flow and a
second warmer
air flow, the heat exchanger comprising:
a heat exchanger unit having a housing containing a plurality of heat
exchanger plates in
mutually arranged relation to form a stack, each plate having four comers and
an aperture
located adjacent each corner, the heat exchanger plates being dimensioned and
configured
such that said apertures overlap to form first, second, third and fourth air
passageways in the
stack, said plates being further configured to form an alternating set of
first and second flat
parallel air chambers in mutual serial relation in the stack, the first said
set of air chambers
being continuous with said first and second air passageways such that air can
pass between
the first and the second air passageways thropgh said first set of air
chambers; said second set
of air chambers being continuous with said third and said fourth air
passageways, such that
air can pass between the third and the fourth air passageways through the
second set of air
chambers;
said stack of heat exchanger plates being further configured such that the
first and. second set
of air chambers are substantially air tight so that air does not leak between
the first and the
second set of air chambers; said heat exchanger unit having a first side and a
second side, the
four said air passageways each having a first o!nd open to said unit first
side at a first port and
an opposite, second end opened to said unit Wond side at a second port; said
first and said
second port being configured to be selectively plugged by a plug member; said
unit having
four said plug members, each plugging one end of a respective said air
passageway; and first,
second, third and fourth air conduits, each oNratively coupled to a respective
one of said air
passageways and carrying a respective one of said first and second air flows.
2. The heat exchanger unit as defined in Claim 1 wherein said first and said
second air
passageways are formed on first opposite diagonal corners of said heat
exchanger plates,

and wherein said third and said fourth air passageways are formed on second
opposite
diagonal corners of said heat exchanger plates.
3. The heat exchanger as defined in claim 2, wherein said first and said
second air
conduits are mounted to said first side of said heat exchanger unit, and said
third and said
fourth air conduits are mounted on said second side of said heat exchanger
unit, said first
air conduit being operatively coupled to two of said ports on said first side
of said heat
exchanger unit, said second air conduit being operatively coupled to two other
said ports
on said first side of said heat exchanger unit; said third air conduit being
operatively
coupled to two of said ports on said second side of said heat exchanger unit,
and said
fourth air conduit being operatively coupled to two other said ports on said
second side
of said heat exchanger unit.
4. The heat exchanger as defined in Claim 3, wherein the heat exchanger
comprises a
plurality of substantially identical said heat exchanger units, each said unit
having its first
said side mounted to said first and second air ponduits, and its said second
side mounted
to said third and fourth air conduits.
5. A heat exchanger plate for use in forming said heat exchanger as defined by
Claim 1,
said heat Exchanger plate comprising:
(a) a sheet having a flat surface and a peripheral rim of predetermined
height;
(b) a first pair of said apertures formed on said sheet of predetermined
diameter and an
projecting peripheral edge;
(c) a pair of projecting collar portions extending perpendicularly from the
sheet having
a rim portion with an outside diameter slightly smaller than the inner
diameter of said
first pair of apertures;

(d) said collar portions and said apertures being located and positioned such
that with
two said heat exchanger plates in mutually stacked relation said collar
portion rims of one
said plate extend through said first pair of apertures of the adjacent said
plate, to form
said first, second, third and fourth air passageways in said stack, said
collar, portions
being further configured to be deformed around the peripheral edge surrounding
said first
pair of apertures to form a substantially air tight seal;
(e) each of said air passageways having a first port at a first end of the
passageway and
a second port at a second end of the passageway, each port being configured to
be
selectively plugged by a plug member, one of a first and second port being
plugged for
each of said first, second , third and fourth air passageways.
6. The heat exchanger plate as defined m Claim 5 wherein each said collar
portion is
formed on said sheet and has a cone shaped base extending at an acute angle
from the
surface of the sheet and tapering to form said collar portion rim, said collar
portion rim
being substantially cylindrical and extending from the base as a shoulder.
7. The heat exchanger plate as defined in Claim 6 wherein said peripheral
edges
surrounding said first pair of apertures contact said shoulders of said collar
portions.
8. The heat exchanger plate as defined in Claim 7 wherein said acute angle is
greater
than approximately 38 degrees.
9. The beat exchanger as defined in Claim 1, wherein each of said apertures
has a
circular peripheral edge, each said beat exchanger plate further including a
pair of collar
portions projecting perpendicularly from the plate, each collar portion having
a rim
defining a circular opening having an external diameter slightly smaller than
the inner
diameter of said aperture, said collar portions and said apertures being in
mutually

positioned relation when said heat exchanger plates are stacked that said
collar portion
rims of one plate are aligned with and extend within said apertures in an
adjacent heat
exchanger plate to form said air passageways; each said collar portion rim
being
configured to be deformed at the peripheral edge surrounding the airway, to
form a
substantially air tight seal.
10. the heat exchanger plate as defined in Claim 5, said sheet being
substantially rectangular, with
four comers, said first pair of apertures and said pair of collar portions
being formed such that
each aperture and each collar portion is positioned adjacent to a comer of the
sheet.

Description

CA 02328312 2000-12-14
TITLE OF THE INVENTION: HEAT EXCHANGER
FIELD OF THE INVENTION:
The invention relates generally to the field of heat exchangers for exchanging
heat between cold
air and heated air.
BACKGROUND OF THE INVENTION:
Countercurrent heat exchangers are well known. They generally consist of a
housing having a
plurality of heat exchanger plates which separate a first flow of fluid from a
second flow of fluid.
The heat exchanger plates generally consist of substantially flat plates
which, while keeping the
first and second flows separate, bring both flows in sufficiently close
proximity to permit heat to
be exchanged between the two flows.
Countercurrent heat exchangers are presently used in several applications,
however, their
use in residential and commercial building has been limited by their high
cost. Heat exchanger
plates are usually welded or bonded together using expensive and time
consuming techniques.
Furthermore, present day heat exchangers are difficult to integrate into
modern forced air heating
and air conditioning systems. Finally, due to their expense and complexity of
design, existing
heat exchangers are difficult to customize. In most cases, a heat exchanger
requires the installer
little flexibility in duct positioning; thereby decreasing its appeal to
builders. A simplified, low
cost and flexible heat exchanger system would be easier to sell to the
residential and commercial
construction industries.
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CA 02328312 2000-12-14
SUMMARY OF THE INVENTION:
The present invention is a heat exchanger for exchanging heat between a cooler
first air
flow and a warmer second air flow. The heat exchanger comprises a heat
exchanger unit having
a housing containing a plurality of heat exchanger plates stacked together to
form a stack. Each
heat exchanger plate has four corners and an aperture located adjacent each
corner, the heat
exchanger plates being dimensioned and configured such that the apertures of
the heat exchanger
plates overlap to form a first, second, third and fourth air passageways in
the stack. The heat
exchanger plates are further configured to form an alternating series of first
and second flat
parallel air chambers in the stack, the first set of air chambers being
continuous with the first and
second air passages such that air can pass between the first and second air
passages through the
first set of air chambers, the second set of air chambers being continuous
with the third and
fourth air passageways such that air can pass between the third and fourth air
passageways
through the second set of air chambers. The stack of heat exchanger plates are
further
configured such that the first and second set or. air chambers are
substantially air tight such that
air does not leak between the first and second set of air chambers. The heat
exchanger unit has a
first and second side, the first, second, third and fourth air passageways
each having a first end
open to the first side of the heat exchanger unit at a first port and an
opposite second end opened
to the second side of the heat exchanger unit at a second port. The stack is
further adapted such
that each port may be selectively plugged by a plug member, the heat exchanger
unit having four
plug members, each plug member plugging one end of each air passageway.
Finally, the first,
second, third and fourth air conduits, are each operatively coupled to one of
the air passageways,
the air conduits carrying the first and second air flows.
2

CA 02328312 2000-12-14
BRIEF DESCRIPTION OF THE DRAWINGS:
FIGURE 1. Is a perspective view of a heat exchanger made in accordance with
the present
invention.
FIGURE 2. Is a top view of a heat exchanger panel made in accordance with the
present
invention.
FIGURE 3. Is a cross sectional view of the panel shown in figure 2 taken along
line A-A.
FIGURE 4. Is a long sectional view of the heat exchanger unit shown in figure
1 taken along
line B-B.
FIGURE 5. Is a long sectional view of the heat exchanger unit shown in figure
1 taken along
line C-C.
FIGURE 6. Is a cross sectional view of a portion of an air passageway section
of a heat
exchanger made in accordance with the present invention wherein the air
passageway has not yet been sealed.
FIGURE 7. Is a cross sectional view of the portion of the heat exchanger unit
shown in figure
6 after the passageway has been sealed.
FIGURE 8. Is a top view of an alternate embodiment of the heat exchanger
panel,
FIGURE 9. Is a cross sectional view of the heat exchanger panel shown in
figure 8 taken
along line F-F.
FIGURE 10. Is a cross sectional view of a portion of an air passageway section
of a heat
exchanger made in accordance with an alternate embodiment of the present
invention wherein the air passageway has not yet been sealed.
FIGURE 11. Is a cross sectional view of the portion of the heat exchanger unit
shown in figure
10 after the passageway has been sealed.
3

CA 02328312 2000-12-14
FIGURE 12. Is a front view of two heat exchangers made in accordance with the
present
invention being mounted on the roof of a building.
DETAILED DESCRIPTION OF THE INVENTION:
Referring firstly to figure 1, a heat exchanger system, shown generally as
item 10, can be
used to transfer the heat from the internal air of a building to the external
air outside of the
building as the internal air is exhausted out of the building and the cooler
outside air is vented
into the building. A heat exchanger system made in accordance with the present
invention
consists of a heat exchanger unit 12 mounted between exhaust conduits 14 and
intake conduits
16. Exhaust conduit 14 consists of parallel conduits 18 and 20 while intake
conduit 16 consists
of parallel conduits 22 and 24. Heat exchanger 12 consists of a plurality of
heat exchanger units
26, each of which is formed from a plurality of heat exchanger plates 28. Heat
exchanger unit 26
has conduit 30 for receiving warm stale air from conduit 18. Heat exchanger
plates 28 channels
the warm stale air from conduit 30 into opposite conduit 32 located on the
other side of the heat
exchanger plates. Air from conduit 32 is exhausted into conduit 20 via a fan
or other means
known in the art.
Heat exchanger unit 26 is also provided with conduits 34 which receives air
from conduit
24. Air from conduit 34 is channeled through heat exchanger plates 28 to
conduit 36 at the
opposite end of plates 28. Conduit 24 is open to the outside of the building,
and is therefore
filled with cooler fresh air. Cooler fresh air is forced into conduit 24 by a
fan or other means and
makes its way into conduit 34. Conduit 34 distributes the cooler fresh air
through plates 28,
which exhaust into conduit 36. Conduit 36 in turn exhausts into conduit 22
which supplies the
inside of the building with fresh air. As warm stale air from inside the
building is forced through
4

CA 02328312 2000-12-14
conduit 18 via a fan or other means, it passes through conduit 30 and out
conduit 32 where it is
in turn passed to conduit 20 and is exhausted out of the building. As the air
passes from conduit
30 to 32, it passes through plates 28. Likewise, as air passes through conduit
34 to conduit 36, it
passes through plates 28. For the purposes of this patent application, the air
flow from conduit
30 to 32 will be referred to as the outgoing air flow, and the air flow from
conduit 34 to 36 will
be referred to as the ingoing air flow. As will be explained in greater
detail, plates 28 are
adapted and configured to separate the ingoing and outgoing air flows into
separate ingoing and
outgoing air channels. These separate air channels are arranged such that the
ingoing and
outgoing air flows travel in parallel but opposite directions through plates
28. As will be
explained in greater detail, plates 28 are further configured such that the
ingoing and outgoing
air channels are in thermal contact, such that a portion of the heat contained
in the warmer air of
the outgoing air channels is transferred to the cooler air of the ingoing air
channel. In this way,
warm stale air from the inside of a building may be used to heat cold fresh
air which is pumped
into the building.
The capacity of heat exchanger plate 10 can be increased simply by increasing
the
number of heat exchanger units 26. Hence, if the heat exchanger capacity of
heat exchanger 10
is to be increased, additional heat exchanger units 26 are mounted between
conduits 14 and 16.
Referring now to figure 2, each heat exchanger plate 28 consists of a
substantially flat
metal plate having a flat surface 38, opposite ends 40 and 42, and opposite
sides 44 and 46.
Surface 38 is provided with a pair of apertures 48 and 50 towards opposite
ends 40 and 42.
Aperture 50 is provided with corrugated rim 52 which assists in the formation
of an air
passageway. Preferably, apertures 48 and 50 located at end 40 are in opposite
orientation to
apertures 48 and 50 located towards end 42.
5

CA 02328312 2000-12-14
Referring now to figure 3, corrugated rim 52 surrounding aperture 50 consists
of outside
wall 58, top 68, middle wall 56, lower portion 62 and inner wall 60. Inner
wall 60, bottom
portion 62 and middle wall 56 are formed such that inner gap 64 is created
separating walls 56
and 60. Likewise, outer walls 58 and middle wall 56 are separated by gap 70.
Aperture 48 is
defined by horizontal wall 72 having shoulder 71 and lip 54. Wall 72 is
substantially
perpendicular to surface 38. Side 44 forms an angular wall rising
perpendicularly from surface
38. Likewise, side 46 forms an angular wall having top surface 76 rising
perpendicularly from
surface 38.
Turning now to figures 4 and 5, each heat exchanger unit 26 is formed from a
plurality of
heat exchanger plates 28 which are stacked one on top of the other within
housing 80 such that
apertures 48 of one heat exchanger plate is alined with aperture 50 of the
heat exchanger plate
immediately below. Apertures 48 and 50 of heat exchanger plates 28 form air
conduits 34, 30,
32 and 36. Heat exchanger plates 28 also form air chambers 84 and 82 which are
separated by
heat exchanger surfaces 38. Due to the sealing arrangement between apertures
48 and 50,
conduit 34 is continuous with chambers 82 while conduit 30 is continuous with
chambers 84.
Conduit 34 is sealed at one end by cap 96 and conduit 30 is sealed at one end
by cap 90. As air
travels through conduit 34 it travels through air chambers 82 and out of air
conduit 36.
Likewise, as air travels through conduit 30 it travels into chambers 84 and
out of conduit 32.
Surfaces 38 of heat exchanger plates 28 separate the air flow in chambers 82
and 84. It will be
appreciated that the air in chamber 82 is flowing in a parallel but opposite
direction to the air in
chambers 84. Since heat exchanger plates 28 are made of aluminum or sheet
metal or some
other such material, heat is exchanged between chambers 82 and 84 in a counter
flow
arrangement.
6

CA 02328312 2000-12-14
One of the advantages of the present heat exchanger plate design is that by
simply
capping different apertures, a different pattern of air flow can be created in
the heat exchanger
unit. For example, considering the embodiment shown in figures 4 and 5, heat
exchanger unit 12
has eight possible ports through which air may pass into or out of the heat
exchanger unit. In
particular, heat exchanger unit 12 has ports 86a, 86b, 92a, 92b, 94a, 94b, 88a
and 88b. These
ports can either be left opened or closed, depending on the particular air
flow pattern desired. In
the particular example shown in figures 4 and 5, ports 86a, 92b, 88a and 94b
are left open, while
ports 92a, 86b, 94a and 88b are closed off by caps 90 and 96. This particular
arrangement of
open and closed ports permits a first airflow D between ports 86a and 88a and
a second air flow
E between ports 94b and 92b. If first airflow D represents the ingoing air
flow and second
airflow E represents the outgoing air flow, then cold fresh air would flow
into port 86a, pick up
heat from airflow E and then exhaust as warmer fresh air out of port 88a.
Likewise, warmer
stale air would enter port 92b, exchange its heat with air flow D, and exhaust
as cooler stale air
out port 94b. By capping different ports, a different air flow pattern can be
created. For
example, by capping ports 88a and 94b and opening ports 88b and 94a, a
different counter
current air flow pattern is created.
It will be appreciated that depending on the needs of the customer, certain
air flow
patterns may be more desirable than others. The particular arrangement shown
in figure 1 shows
fresh air being carried by conduits 24 and 22 of intake conduits 16 while
stale air is carried in
conduits 18 and 20 of exhaust conduit 14. In some applications, this
particular arrangement may
not be optimal since there will be a temperature difference between conduits
24 / 22 and
conduits 18 / 20. In some applications, this may result in condensation build
up. If condensation
buildup is a problem, it may be preferable to keep both of the "warm" air
flows together in the
7

CA 02328312 2000-12-14
same intake or exhaust conduit. The versatility of the present design permits
each heat
exchanger unit to be customized to meet particular applications. All that is
required to alter the
internal air flow pattern is a number of caps 90 and 96. In this way, each
heat exchanger can be
tailored to the specific needs of the customer.
Referring now to figure 6, the method of sealing heat exchanger plates 28 will
now be
disclosed. The inside diameter of aperture 48 is selected such that lip 72 of
first heat exchanger
plate 98 can fit between middle wall 56 and inner wall 60 of lower heat
exchanger plate 100.
Surfaces 38 of heat exchanger plates 98 and 100 define chamber 102. The height
of walls 58
and 56 define the height of chamber 102. Outer wall 58 and middle wall 56 form
a rigid annular
structure which supports heat exchanger plate 98. Aperture 48 is dimensioned
such that lip 72
fits within gap 64 defined by middle wall 56 and inner wall 60 of heat
exchanger plate 100.
Inner wall 60 is dimensioned such that lip 66 projects above surface 38 of
heat exchanger plate
98.
As seen in figure 7, plate 98 and 100 are sealed together such that relatively
little air
leaks from chamber 102 into aperture 50. The sealing is accomplished by
deforming inner wall
60 and adjacent lip 66 such that lip 66 makes contact with shoulder 71 of
upper heat exchanger
plate 98. To ensure that lip 66 makes contact with shoulder 71 all along the
periphery of
aperture 50, lip 72 is selected to be sufficiently long such that rim 54 of
lip 72 makes contact
with lower portion 62 of lower heat exchanger plate 100. This structure
permits lip 72 to resist
the force of the tool which is used to deform edge 66 against shoulder 71. It
has been discovered
that if edge 54 of lip 72 does not make contact with bottom portion 62, then a
tight seal between
shoulder 71 and edge 66 is less likely to occur.
An alternate embodiment of the heat exchanger plates of the present invention
is shown
8

CA 02328312 2000-12-14
in Figures 8, 9, 10 and 11. The alternate embodiment essentially consists of
an alternate
structure for the sealing of the heat exchanger plates. As seen in Figure 8,
heat exchanger plate
150 consists of a substantially flat metal plate having flat surface 152
opposite ends 154 and 156
and opposite sides 158 and 160. Flat surface 152 is provided with a pair of
apertures 162 and
164 toward end 154 and apertures 166 and 168 toward end 156. Apertures 164 and
166 are
provided with rim 170 and 172, respectively.
Referring now to Figure 9, rim 172 consists of a cone like base 176
surrounding a
cylindrical collar 174. Base 176 is at an angle (alpha) relative to flat
surface 152. Collar 174 is
at an angle beta to base 176. It will be appreciated that base 176 consists of
a cone-like base
extending outwardly from collar 174. Collar 174 has an upper rim 182 which
defines the
diameter of opening 166. Base 176 and collar 174 are dimensioned such that rim
182 projects
above ledges 178 and 180. Aperture 162 is formed on flat surface 152 as a
simple aperture
having rim 176. The diameter of aperture 162 is slightly higher than the
outside diameter of
collar 174. Preferably, aperture 162 is approximately 20 thousandth in radius
larger than the
outside diameter of collar 174.
Referring now to Figures 10 and 11, heat exchanger plates 150 can be stacked
one on top
of the other as in the previous embodiment. When heat exchange plates 150 are
stacked one on
top of the other, a plurality of parallel air chambers 188 and 190 are formed.
An air passage
way connecting air chambers 190 is formed by openings 166, and base 176.
Collar portion 174
of a lower heat exchanger plate is inserted into aperture 162 of a
corresponding upper heat
exchanger plate such that collar portion 174 pass through aperture 162, as
shown in Figure 10.
To seal the gap separating rim 196 from collar 174, collar 174 is bent around
rim 196 as shown
in Figure 11. Angle alpha is selected to ensure that collar 174 can be
deformed to seal aperture
9

CA 02328312 2000-12-14
162 without causing flat surfaces 152 to deform. It has been discovered that
if angle alpha
equals 38 degrees or less, and if collar 174 is approximately 0.03 inches in
height between rim
182 and point 184 where the collar meets base 176, then wall 174 may be bent
around rim 196 of
aperture 162 without causing any significant deformation of flat surface 152.
Experiments using
aluminum 50-52 sheeting having a thickness of .02 inches, showed that an angle
alpha of 38
degrees permitted tight sealing of aperture 162 without significant buckling
of surface 152. By
contrast, when Alpha angles of 40 degrees or 42 degrees were attempted,
significant buckling of
flat surface 152 occurred. Furthermore, where alpha was greater than 38
degrees, very poor
ceiling around rim 196 was obtained.
As mentioned previously, one of the advantages of the present invention is how
the air
flow patterns in the heat exchanger can be modified to suit the particular
needs of the customer.
This is particularly evident when two heat exchangers are to be coupled for
high volume
applications. Referring now to figure 12, if building 200 requires a higher
capacity of fresh air
ventilation, then two heat exchangers, 104 and 106 may be mounted to roof 202.
In order to
ensure that only one hole is made in the roof to accommodate the exhaust
ducts, exhaust conduit
108 of heat exchanger 106 and exhaust conduit 110 of heat exchanger 104 can be
arranged such
that the two exhaust conduits are side by side. This side by side arrangement
permits the exhaust
conduits of both heat exchangers 104 and 106 to be coupled to the same exhaust
fan (not shown),
thereby simplifying the installation of the units.
Specific embodiments of the present invention have been disclosed; however,
several
variations of the disclosed embodiments could be envisioned as within the
scope of this
invention. It is to be understood that the present invention is not limited to
the embodiments
described above, but encompasses any and all embodiments within the scope of
the following

CA 02328312 2000-12-14
claims.
11

Representative Drawing