U.S. patent application number 09/960307 was filed with the patent office on 2002-04-18 for apparatus.
Invention is credited to Wilson, George.
Application Number | 20020043362 09/960307 |
Document ID | / |
Family ID | 9900050 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020043362 |
Kind Code |
A1 |
Wilson, George |
April 18, 2002 |
Apparatus
Abstract
A heat exchanger has two inlets and two outlets for two
counterflow air paths through a stack plates. The plates are
vacuum-formed, each having a section with zigzag walls forming
multiple flow channels between adjacent plates. The edges of the
plates have walls that nest with one another and are retained and
sealed between ribs on two side plates. Four grilles at the inlets
and outlets have bars with recesses retaining the edges of pairs of
plates, the bars being separated by spaces allowing air to flow
between adjacent pairs of plates and into or out of the air
paths.
Inventors: |
Wilson, George; (Tockwith,
GB) |
Correspondence
Address: |
Burton A. Amernick
Connolly Bove Lodge & Hutz LLP
Suite 800
1990 M Street, N.W.
Washington
DC
20036-3425
US
|
Family ID: |
9900050 |
Appl. No.: |
09/960307 |
Filed: |
September 24, 2001 |
Current U.S.
Class: |
165/166 |
Current CPC
Class: |
F28F 2275/085 20130101;
F28D 9/0068 20130101; F28F 9/001 20130101; F28F 3/046 20130101;
F28F 2250/108 20130101 |
Class at
Publication: |
165/166 |
International
Class: |
F28F 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2000 |
GB |
0023427.8 |
Claims
What I claim is:
1. A heat exchanger comprising: a plurality of plate members
stacked parallel above one another to define two separate fluid
flow paths between alternate pairs of adjacent plate members; and
retainers for retaining said plate members with one another,
wherein said retainers include a plurality of first and second
surfaces facing one another, and wherein respective pairs of said
plate members are retained between said first and second surfaces
in scaling engagement with one another.
2. A heat exchanger according to claim 1, wherein said retainers
have projecting ribs, wherein said first and second surfaces are
provided on said projecting ribs, and wherein edges of said plates
members extend between said ribs.
3. A heat exchanger according to claim 1, wherein said retainers
include two imperforate side plates.
4. A heat exchanger according to claim 1, wherein said retainers
includes four grille members located at inlets and outlets of the
heat exchanger.
5. A heat exchanger according to claim 4, wherein said grille
members are slidable along the plane of a face of the exchanger,
wherein said grille members retain an edge of adjacent plate
members in sealing engagement and retain a gap between retained
pairs of plate members opening into one of said fluid flow
paths.
6. A heat exchanger according to claim 1, wherein the heat
exchanger has inlet and outlet faces on adjacent faces of the
exchanger.
7. A heat exchanger according to claim 5, wherein the heat
exchanger has inlet and outlet faces on adjacent faces of the
exchanger, and wherein respective ones of said grille members on
adjacent faccs are slidable towards one another to form a seal
between adjacent edges of said grille members.
8. A heat exchanger according to claim 1, wherein said plate
members have a plurality of internal walls defining multiple flow
channels therebetween along said plate members.
9. A heat exchanger according to claim 8, wherein said internal
walls and channels on one side of said plate members have
corresponding channels and walls on their opposite side.
10. A heat exchanger according to claim 8, wherein said channels
have a zigzag pattern.
11. A heat exchanger according to claim 1, wherein said plate
members have a spacer to retain separation between adjacent plate
members over their surface.
12. A heat exchanger according to claim 8, wherein said plate
members have a spacer to retain separation between adjacent plate
members over their surface, wherein said spacer includes a
projection in a channel, and wherein an internal wall adjacent said
projection is reduced so that air flow along said channels is not
impeded by said projection.
13. A heat exchanger according to claim 1, wherein said plate
members are vacuum formed from plastics.
14. A heat exchanger according to claim 1, wherein said plate
members are of a carbon-loaded uPVC.
15. A heat exchanger according to claim 1, whcrein said plate
members are of a black colour.
16. A heat exchanger according to claim 1, wherein said plate
members have six sides, and wherein four of said sides are closed
and two of said sides are open.
17. A heat exchanger according to claim 16, wherein each said plate
member has a side wall along the four closed sides, and wherein
side walls of adjacent plate members nest with one another.
18. A heat exchanger according to claim 17, wherein some of said
side walls have an M-shape profile.
19. A heat exchanger according to claim 1, wherein each said plate
member has a main section of rectangular shape and inlet and outlet
sections of triangular shape at opposite ends.
20. A heat exchanger according to claim 19, wherein said inlet and
outlet sections have a plurality of ribs extending generally
transverse to the direction of flow.
21. A heat exchanger comprising: two inlet faces; two outlet faces;
a plurality of plate members stacked parallel above one another to
define two separate fluid flow paths between alternate pairs of
adjacent plate members, each fluid flow path opening at a
respective ones of said inlet and outlet faces; and at least one
grille member slidable along the plane of a face of the exchanger,
said grille member being arranged to retain. an edge of adjacent
ones of said plate members as a pair in sealing engagement and
arranged to retain a gap betwcen said pairs providing an opening
into one of said fluid flow paths.
22. A heat exchanger according to claim 21, wherein said inlet and
outlet faces are on adjacent faces of the exchanger, and wherein
respective ones of said grille members on adjacent ones of said
faces are slidable towards one another to form a seal between
adjacent edges of said grille members.
23. A plate member for a heat exchanger having a stack of said
plate members, wherein said plate member has a main rectangular
region having two parallel sides formed with walls shaped to nest
with corresponding walls of adjacent plate members and having a
plurality of flow channels extending generally longitudinally
parallel to said parallel sides; and triangular inlet and outlet
regions at opposite ends of said main region, said triangular
regions each having an edge extending along one side adapted to
nest with a corresponding edge of an adjacent plate member and each
having an open side through which air can enter and leave from
between adjacent plate members, said inlet and outlet regions being
shaped to channel air to and from said flow channels.
24. A heat exchanger comprising: a plurality of pjate members
stacked parallel above one another to define two separate fluid
flow paths between alternate pairs of adjacent plate members; two
side plates having a plurality of parallel ribs between which two
side edges of said plate members are retained in sealing
engagement; four grilles having a plurality of parallel bars
separated from one another by spaces, said bars having recesses
within which edges of two adjacent plate members are received, said
grilles and plate members being arranged such that air can flow
from one of said grilles to another of said grilles in one
direction between pairs of adjacent ones of said plate members and
from a third of said grilles in an opposite direction between
different pairs of adjacent ones of said plate members to a fourth
of said grilles.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to heat exchangers.
[0002] The invention is more particularly concerned with heat
exchangers for use in building ventilation systems.
[0003] Heat exchangers arc used in building ventilation systems to
transfer heat from warm air extracted from the building to cold air
supplied to the building. In this way, the amount of energy needed
to maintain the temperature within the building can be
minimized.
[0004] A common form of heat exchanger used in building ventilation
systems comprises a stack of thin parallel plates spaced from one
another to form two separate flow paths between alternate pairs of
plates. The warm air is supplied along one path and a part of its
heat is conducted through the thickness of the plates to the cold
air supplied along the other path.
[0005] The ideal heat exchanger should have a high efficiency of
thermal transfer, preferably above about 90% and should produce
only a low back pressure so as to reduce energy expenditure by the
fans used to pass the air through the exchanger. The exchanger
should also have a low leakage between the two air paths and be
easy to manufacture at low cost.
[0006] The plates used in heat exchangers usually have low
projecting walls to support the plates spaced from one another and
to enhance performance. In one arrangement, the plates are moulded
with zigzag paths on opposite sides, the plates being atranged with
the paths out of phase with one another so as to ensure that the
flow paths are kept open. Such an arrangement may have a high
efficiency but produces a high back pressure because it results in
considerable interruption to the air flow path as it passes between
the intersecting walls on facing plates.
[0007] Conventional heat exchangers have the edges of their plates
bonded with one another such as by an adhesive, solvent or by
ultrasonic welding. These processes can produce effective seals
between the two flow paths but are relatively expensive and require
specialised machinery.
BRIEF SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide an
alternative heat exchanger.
[0009] According to one aspect of the present invention there is
provided a heat exchanger including a plurality of plate members
stacked parallel above one another to define two separate fluid
flow paths between alternate pairs of adjacent plate members, and
retaining means for retaining the plate members with one another,
the retaining means including a plurality of first and second
surfaces facing one another between which edges of respective pairs
of plate members are retained in sealing engagement with one
another.
[0010] The first and second surfaces are preferably provided on
projecting ribs between which edges of pairs of the plate members
extend. The retaining means may include two imperforate side plates
and may include four grille members located at each of the inlets
and outlets of the heat exchanger. The grille members may be
slidable along the plane of a face of the exchanger, the grille
members retaining an edge of adjacent plate members in sealing
engagement and retaining a gap between retained pairs of plate
members opening into one of the fluid flow paths. The beat
exchanger preferably has inlet and outlet faces on adjacent faces
of the exchanger. Respective grille members on adjacent faces may
be slidable towards one another to form a seal between adjacent
edges of the grille members. The plate members preferably have a
plurality of internal walls defining multiple flow channels
therebetween along the plate members. The internal walls and
channels on one side of the plate members preferably have
corresponding channels and walls on their opposite side. The
channels may have a zigzag pattern. The plate members may have
spacer means to retain separation between adjacent plate members
over their surface. The spacer means may include a projection in a
channel, an internal wall adjacent the projection being reduced so
that air flow along the channels is not impeded by the projection.
The plate members may be vacuum formed from plastics and may be of
carbon-loaded UPVC. Preferably the plate members are of a black
colour. The plate members may have six sides, four of the sides
being arranged to be closed and two of the sides arranged to be
open. Each plate member preferably has a side wall along the four
closed sides, the side walls of adjacent plate members nesting with
one another. Some of the side walls may have an M-shape profile.
Each plate member preferably has a main section of rectangular
shape and inlet and outlet sections of triangular shape at opposite
ends. The inlet and outlet sections preferably have a plurality of
ribs extending generally transverse to the direction of flow.
[0011] According to another aspect of the present invention there
is provided a heat exchanger including a plurality of plate members
stacked parallel above one another to define two separate fluid
flow paths between alternate pairs of adjacent plate members, each
fluid flow path opening at a respective inlet and outlet face of
the exchanger, and the exchanger including at least one grille
member slidable along the plane of a face of the exchanger and
arranged to retain an edge of adjacent plate members as a pair in
sealing engagement and to retain a gap between the pairs providing
an opening into one of the fluid flow paths.
[0012] The heat exchanger preferably has inlet and outlet faces on
adjacent faces of the exchanger, respective grille members on
adjacent faces being slidable towards one another to form a seal
between adjacent edges of the grille members.
[0013] According to a further aspect of the present inventi on
there is provided a plate member for a heat exchanger according to
the above one or other aspect of the invention.
[0014] According to a fourth aspect of the present invention there
is provided a plate member for a heat exchanger having a stack of
plate members, the plate member having a main rectangular region
having two parallel sides formed with walls shaped to nest with
corresponding walls of adjacent plate members and having a
plurality of flow channels extending generally longitudinally
parallel to the parallel sides, and triangular inlet and outlet
regions at opposite ends of the main region, the triangular regions
each having an edge extending along one side adapted to nest with a
corresponding edge of an adjacent plate member and each having an
open side through which air can enter and leave from between
adjacent plate members, the inlet and outlet regions being shaped
to channel air to and from the flow channels.
[0015] A heat exchanger assembly according to the present
invention, will now be described, by way of example, with reference
to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic plan view of the assembly;
[0017] FIG. 2 is a perspective view of the heat exchanger unit;
[0018] FIG. 3 is a perspective view of a top or base plate of the
unit;
[0019] FIG. 4 is a perspective view of a side plate of the
unit;
[0020] FIG. 5 is a perspective view of an end grille;
[0021] FIG. 6 is a sectional side elevation of the grille of FIG. 5
along the line VI-VI of FIG. 5;
[0022] FIG. 7 is a perspective view of one type of heat exchanger
plate;
[0023] FIG. 8 is a perspective view of another type of heat
exchanger plate;
[0024] FIG. 9 is an enlarged plan view of a part of one of the heat
exchanger plates;
[0025] FIG. 10 is a cross-sectional side elevation of the plate
along the line X-X of FIG. 9;
[0026] FIG. 11 is a cross-sectional side elevation view of a lower,
side part of the heat exchanger unit showing how the exchanger
plates are retained by the side plates; and
[0027] FIG. 12 is a cross-sectional side elevation view of an
upper, end part of the heat exchanger unit showing how the
exchanger plates are engaged by the grilles.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0028] With reference first to FIGS. 1 and 2, the heat exchanger
assembly has an outer housing 1 with two inlets 2 and 3 and two
outlets 4 and 5 located at four corners of the housing. A heat
exchange unit 6 is located in the housing 1 and defines two
separate air flow paths 7 and 8 through the housing. The first flow
path 7 extends from the inlet 2 through the exchange unit 6 to the
outlet 4 in the opposite comer and, in use, receives warm air
exhausted from a room. The second flow path 8 extends ftom the
other inlet 3 to the other outlet 3 and, in use, receives cold air
from outside. The exchange unit 6 operates to transfer heat from
the air flowing along the first flow path 7 to air flowing along
the second flow path 8 so that the fresh air supplied to the
building is warmed. The assembly includes two conventional electric
fans 10 and 11 located in the housing 1 at the two outlets 4 and 5
to draw air along the respective flow paths 7 and 8.
[0029] The heat exchange unit 6 is of the counter-flow type having
two parallel, vertical sides 61 and 62 and four end faces 63 to 66
providing the two inlets and outlets. The unit 6 has a horizontal
base 67 and top 68. Operation of the two fans 10 and 11 causes warm
air drawn in through the inlet 2 of the housing to flow in the
inlet face 63, through the unit 6 and out of the diagonally
opposite outlet face 65, from where it flows to the outlet 4. Cold
air drawn in through the inlet 3 passes in the inlet face 64,
through the unit 6 and out of the diagonally opposite outlet face
66, from where it passes to the outlet 5.
[0030] With reference now also to FIGS. 3 to 12, the beat exchange
unit 6 comprises a parallel stack of forty-four, six-sided heat
exchanger plates 70. The plates 70 are contained within a base
plate 12, a top plate 13, two side plates 14 and 15 and four inlet
grilles 16 to 19. Each plate 70 is formed with walls at its edges
to provide a seal around four of its six sides, leaving two
diagonally-opposite sides open fbr inlet and outlet of air. The
heat exchanger plates 70 are vacuum formed from a thin sheet of
carbon4oaded uPVC of a black colour, which has a high thermal
conductivity and is an efficient thermal radiator. The plates 70
are moulded with a pattern of internal walls to form channels
therebetween on opposite surfaces that act to contain air flowing
through the exchanger along defined paths through the exchange unit
6. The heat exchanger plates 70 are of two different types: a lower
type A and an upper type 13, which are stacked alternately one
above the other. The configuration of the lower type of plate 70A
will now be described with reference to FIG. 7.
[0031] The plate 70A has a main section 71 of rectangular shape
with forty-three internal walls 72 of zigzag shape extending
parallel with one another longitudinally of the plate and defining
forty-two zigzag channels 73 extending along the plate between the
walls. The walls 72 project vertically on the upper surface of the
plate and are moulded from the material of the platcs so as to form
a corresponding pattern of channels and walls on the underside of
the plate.
[0032] At opposite ends of the main section 71, the plate 70A has
an inlet and outlet section 74 and 75, both of triangular shape.
One side 76 of the inlet section 74 has a raised edge wall 77, to
close the side, and the other side 78 is open with a slightly
lowered edge 79. Where the raised wall 77 meets the open side 78
there is a small step 177 aligned longitudinally of the plate. The
surface of the inlet section 74 is ribbed with shallow, parallel
ribs 80 extending laterally of the plate and generally transversely
to the direction of air flow. The inlet section 74 also has three
higher raised walls 81 extending perpendicular to the open side 78.
These nbs 80 and walls 81 act to channel air entering the open side
78 substantially evenly across the row of ends of the zigzag
channels 73. The ribs 80 also introduce a small amount of
turbulence into the air flow. The outlet section 75 similarly has a
closed side 82 with a raised wall 83, and an open side 84 which
connects with the closed side via a step 183. The outlet section 75
also has ribs 85 and walls 86 to help channel air emerging from the
zigzag channels 73 to the open side 84 of the section. A location
pip 87 projects upwardly at opposite ends of the plate 70A, just
within the apex of the inlet and outlet sections 74 and 75. The two
sides of the main section 71 are each closed by a raised wall 90
having an M-shape profile (FIG. 11) extending longitudinally along
the plate.
[0033] The upper type of plate 70B (FIG. 8) has similar surface
formations, which are given the same number as the formations for
plate 70A with the addition of a prime '. The inlet section 74' of
the upper plate 70B is at the opposite end from that of the lower
plate 70A. The plates 70B are stacked alternately above the plates
70A and have a pattern of zigzag channels 73' identical with the
channels 73 except that they are displaced slightly laterally such
that the walls 72' align with the channels 73. In this way, the
channels defined by the underside of the walls 72' are aligned with
the channels 73 on the upperside of the plates 70A to form channels
between adjacent plates of diamond shape in section. The top ofthe
internal walls 72 on the plates 70A support the base of the
channels 73' on the plates 70B.
[0034] Along the two sides, the main section 71' of the plate 70B
has side walls 90' of reduced height and of M-shape in section,
which nest on the top of the side walls 90 of the lower plates
70A.
[0035] The triangular inlet and outlet sections 74' and 75' at the
ends of the upper plates 70B are also similar to those of the lower
plates 70A except that different ones of the sides 76', 78', 82'
and 84' are open and closed and the internal ribs 80', 85' and
walls 81', 86' act to channel air between the open sides 78', 84'
and the ends of the zigzag channels 73'. The inlet and outlet
sections 74' and 75' simlarly have locating pips 87' the underside
of which are engaged by the locating pips 87 on the lower plates
70A.
[0036] In order to ensure that the zigzag walls on adjacent plates
do not nest with one another and thereby restrict flow, the pattern
of zigzag walls is interrupted over the surface of the lower plate
70A by several raised pips 92 (FIGS. 9 and 10) located in channels
73 between the internal walls 72. The walls 72 in the region of
these pips 92 is reduced in height to form notches 93 so that air
flowing along the channels 73 can flow through the notches into
adjacent channels and is not restricted by the presence of the
pips.
[0037] The plates 70A and 70B are held together with one another in
a stack by means of the bottom plate 12, top plate 13, side plates
14 and 15 andthe grilles 16 to 19. The side plates 14 and 15 (shown
most clearly in FIGS. 4 and 11) are imperforate and moulded of a
rigid, black ABS plastics material with twenty-three parallel ribs
95 extending horizontally along their length. The spacing between
adjacent ribs 95 and their height are such that each pair of ribs
receives between them the mated side walls 90 and 90' of a pair of
plates 70A and 70B, the facing surfaces 195 of adjacent ribs
retaining and clamping the two walls together to form a secure
seal.
[0038] The four grilles 16 to 19 (shown most clearly in FIGS. 5, 6
and 12) are each of similar construction, having twenty-three
horizontal, parallel cross-bars 97 spaced apart from one another to
form slots 98 through which air can enter between adjacent pairs of
plates. The external surface of the cross-bars 97 is rounded to
give an aerodynamic profile promoting free flow of air into the
slots 98. Internally, each cross-bar 97 has a recess 99 with
opposite facing surfaces 199 between which the edges of a pair of
plates 70A and 70B are received and retained together in sealing
engagement. The grilles 16 to 19 are assembled on the unit 6 by
aligning one end of the recesses 99 with the corners of the
exchanger plates 70A and 70B where they are supported by the side
plates 14 and 15 so that the edges of a pair of plates locates in
respective recesses. The grilles 16 to 19 are then slid along their
length, parallel to the edge of the plates 70A and 70B, towards the
apex. Where two grilles 16 and 19, 17 and 18 meet at the apex, they
clamp onto the steps 177 and 183 on the plates 70A and 70B to
ensure a good sealing fit along the end of the unit 6. Each grille
16 to 19 has an L-shape ledge 100 along the vertical edge, which
locates at the apex. Each grille 16 to 19 also has an angled ledge
101 along its opposite edge, which overlaps the edge of the
adjacent side plate 14, 15. Along the top and bottom vertical edge
of each grille 16 to 19 extends a channel 102 with clips 103, which
fasten onto the edges of the top and bottom plates 13 and 12.
Similarly, the top and bottom plates 13 and 12 both have channels
104 along their sides with clips 105 (FIG. 11), which fasten onto
the top and bottom edges of the side plates 14 and 15.
[0039] Considering the grilles 16 and 19 at one end of the unit 6,
one of these grilles 16 seals together the edge 84 of each lower
plate 70A to the edge 84' of the upper plate 70B directly below it.
The slots 98 in the grille 16, therefore, open into spaces between
the upper surface of the lower plates 70A and the lower surfaces of
the upper plates so that the air flow path 7 extends between these
surfaces. The adjacent grille 19, however, seals together the edge
83 of each lower plate 70A to the edge 83' of the upper plate 70B
directly above it so that the slots 98 in the grille open into the
air flow path 8 extending between the upper surface of the upper
plates and the lower surface of the lower plates. The warm air
flowing along flow path 7 flows along the channels 73, 73' in a
direction that is parallel to but opposite from the cold air
flowing along the flow path 8. Heat in the exhaust air flow path 7
is conducted through the thickness of the plates 70A and 70B into
the inlet air flow path 8. The construction and arrangement of the
plates 70A and 70B ensure that the heat only has to flow through a
single layer of material between adjacent flow paths.
[0040] The unit 6 is assembled by clipping the side plates 14 and
15 into the base plate 12 and then sliding a pair of heat exchange
plates 70A and 70B into the gaps between the ribs 95 along the side
plates, with the plates being located together by engagement of the
pip 87 in the lower plate in the corresponding location point 87'
in the upper plate. When all the pairs of plates 70 have been slid
into position, the top plate 13 is clipped onto the upper edge of
the side plates 14 and 15. The grilles 16 to 19 are then slid into
place in the manner previously described. In this way, the entire
unit 6 can be assembled without the use of adhesives, solvents and
without having to weld or bond components together.
[0041] The heat exchanger unit 6 has six vertical edge projections
111 to 116 located around its surface and provided on the grilles
16 to 19 and side plates 14 and 1S. These projections are a close
sliding fit in channels 211 to 216 formed on the inside surface of
the housing 1, which is of a foamed plastics material, so that the
unit 6 can be slid down into the housing. The engagement of the
projections 111 to 116 in the channels 211 to 216 forms a seal
preventing passage of air between the outside of the exchange unit
6 and the inside of the housing 1.
[0042] The arrangement of the present invention has several
advantages. The manner in which the plates are retained together at
their edges avoids the need fbr any adhesive or welding, thereby
considerably simplifying assembly and reducing costs. The aligned,
zigzag air flow paths on the upper surface of one plate and the
lower surface of an adjacent plate enables a relatively low
back-pressure to be achieved, whilst the spacer pips ensure that
the air flow paths remain open. Previous exchange plates with
zigzag path have been arranged out of phase with one another so
that the walls on adjacent plates cross and support one another.
This previous arrangement produces considerable air flow
disturbance and results in relatively high back-pressure compared
with the arrangement of the present invention. By sliding the
grilles into position the alignment of the grilles with the
individual plates is considerably simplified compared with
alternative arrangements.
* * * * *