U.S. patent application number 12/846588 was filed with the patent office on 2011-02-03 for heat exchanger.
This patent application is currently assigned to Prodigy Energy Recovery Systems, Inc.. Invention is credited to Rana Bose, David Velan.
Application Number | 20110024080 12/846588 |
Document ID | / |
Family ID | 43514037 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110024080 |
Kind Code |
A1 |
Bose; Rana ; et al. |
February 3, 2011 |
Heat Exchanger
Abstract
Disclosed herein is a heat exchange apparatus. The apparatus
comprises one or more double walled conduit, each having an outer
conduit and an inner conduit located coaxially inside the outer
conduit. The conduits define a first fluid passageway for cold
water at a first temperature. A drain defines a second fluid
passageway for grey water at a second temperature and is located in
the drain and downstream of the grey water flowing therethrough.
The grey water when flowing in the second fluid passageway effects
heat transfer to the cold water flowing in the first fluid
passageway across the inner and outer conduits.
Inventors: |
Bose; Rana; (Montreal,
CA) ; Velan; David; (Montreal, CA) |
Correspondence
Address: |
EDWARDS ANGELL PALMER & DODGE LLP
P.O. BOX 55874
BOSTON
MA
02205
US
|
Assignee: |
Prodigy Energy Recovery Systems,
Inc.
Montreal
CA
|
Family ID: |
43514037 |
Appl. No.: |
12/846588 |
Filed: |
July 29, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61323441 |
Apr 13, 2010 |
|
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|
61229424 |
Jul 29, 2009 |
|
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Current U.S.
Class: |
165/71 |
Current CPC
Class: |
F28D 21/0012 20130101;
Y02A 20/302 20180101; F28D 7/08 20130101; F28F 1/32 20130101; F28F
2265/16 20130101; Y02A 20/30 20180101; Y02B 30/56 20130101; F28D
3/02 20130101; F28D 7/024 20130101; E03C 2001/005 20130101; F28F
1/003 20130101; F28F 13/12 20130101; Y02B 30/566 20130101; F28F
19/01 20130101; F28D 15/02 20130101; F28F 9/02 20130101 |
Class at
Publication: |
165/71 |
International
Class: |
F28F 99/00 20060101
F28F099/00 |
Claims
1. A heat exchange apparatus, the apparatus comprising: a) at least
one double walled conduit having an outer conduit and an inner
conduit located coaxially inside the outer conduit, and defining a
first fluid passageway for a first fluid at a first temperature;
and b) a drain defining a second fluid passageway for a second
fluid at a second temperature, the double walled conduit being
located in the drain and downstream of the second fluid flowing
therethrough, such that the second fluid when flowing in the second
fluid passageway effects heat transfer to the first fluid flowing
in the first fluid passageway across the inner and outer
conduits.
2. The apparatus, according to claim 1, in which the inner conduit
includes an outer wall, the outer conduit includes an inner wall,
the outer wall being located against the inner wall to define a
leak passageway therebetween.
3. The apparatus, according to claim 2, in which the outer conduit
includes an inner knurled surface that is pressed against the outer
wall of the inner conduit to define the leak passageway.
4. The apparatus, according to claim 1, in which the double walled
conduit is helical.
5. The apparatus, according to claim 1, includes an outer helical
double wall conduit, a central helical double wall conduit and an
inner helical double wall conduit.
6. The apparatus, according to claim 5, in which the outer, central
and inner helical double walled conduits are assembled
concentrically.
7. The apparatus, according to claim 6, in which the circumference
of the helices of the double wall conduits decreases from the outer
conduit to the inner conduit.
8. The apparatus, according to claim 5, in which the helical
conduits are coiled in the same direction.
9. The apparatus, according to claim 8, in which the helical
conduits are coiled in a counterclockwise direction.
10. The apparatus, according to claim 8, in which the helical
conduits are coiled in a clockwise direction.
11. The apparatus, according to claim 6, in which each conduit
includes a bend located at an upper end of the assembled helical
conduits.
12. The apparatus, according to claim 1, in which the first and
second fluids flow in a contra-flow manner through the heat
exchange apparatus.
13. The apparatus, according to claim 1, in which the drain is a
drain conduit.
14. The apparatus, according to claim 13, in which the drain
conduit includes an upper drain portion connected to a drain
trap.
15. The apparatus, according to claim 13, includes a bypass conduit
connected to the drain conduit, the bypass conduit having a mesh
for blocking particulate material.
16. The apparatus, according to claim 13, includes a deflector
located in a central core of the drain conduit.
17. The apparatus, according to claim 13, includes a vertically
orientated conduit located at the top of the central core of the
drain conduit and having a plurality of holes located therein.
18. The apparatus, according to claim 17, in which a cap is located
on top of the vertically orientated conduit for temporarily
blocking a central bypass channel.
19. The apparatus, according to claim 18, in which the cap is
operated manually or automatically.
20. The apparatus, according to claim 16, in which the deflector is
a cone with side plates for forcing the second fluid away from the
conduit.
21. The apparatus, according to claim 1, in which a plurality of
helical conduits are stacked adjacent each other in the drain
conduit.
22. The apparatus, according to claim 21, includes four stacked
helical conduits.
23. The apparatus, according to claim 21, in which the helical
conduits include a common first fluid inlet and a common first
fluid outlet.
24. The apparatus, according to claim 1, is orientated orthogonal
to the ground.
25. The apparatus, according to claim 1, is orientated horizontal
to the ground.
26. The apparatus, according to claim 1, is connected to a drain
trap in a shower.
27. The apparatus, according to claim 1, in which the double walled
conduit is serpentine.
28. The apparatus, according to claim 27, in which at least a
portion of the serpentine double walled conduit is located in the
drain.
29. The apparatus, according to claim 27, in which at least one
serpentine double wall conduit is connected to an elongate housing
having two sidewalls and passes through an upper set of openings
located in the sidewalls.
30. The apparatus, according to claim 29 in which a first plurality
of conduit elbows extend away from the sidewalls along
substantially the entire length of the elongate housing.
31. The apparatus, according to claim 29, in which a second
serpentine double wall conduit is connected to the elongate housing
and passes through a lower set of openings located in the
sidewalls.
32. The apparatus, according to claim 31, in which a second
plurality of conduit elbows extend away from the sidewalls along
substantially the entire length of the elongate housing.
33. The apparatus, according to claim 29, in which a plurality of
fins are mounted around the outer wall of the serpentine conduits,
the fins being disposed parallel to each other and extend
substantially the entire length of the elongate housing.
34. The apparatus, according to claim 1, includes a turbulator
located in the drain or the helical conduit.
35. The apparatus, according to claim 1, in which the drain is a
drain plate having a drain plate inlet and a drain plate outlet and
a drain plate surface through which at least a portion of the
double wall conduit extends, the drain plate surface being of
sufficient area to define the second fluid passageway for the
second fluid such that the second fluid flows as a fluid film along
the second fluid passageway.
36. The apparatus, according to claim 35, in which a plurality of
double walled conduits extend parallel along the drain plate.
37. The apparatus, according to claim 35, in which the drain plate
is orientated horizontal relative to the ground.
38. The apparatus, according to claim 35, in which the drain is
angled relative to the ground.
39. The apparatus, according to claim 35, includes a plurality of
serpentine double walled conduits.
40. The apparatus, according to claim 39, in which the serpentine
conduits are sufficiently spaced apart top allow the second fluid
to flow thereover.
41. The apparatus, according to claim 1, in which the drain is a
trench drain.
42. The apparatus, according to claim 1, in which the first fluid
is cold water.
43. The apparatus, according to claim 1, in which the second fluid
is grey water.
44. The apparatus, according to claim 1, in which a heating wire is
located inside the double walled conduit.
45. The apparatus, according to claim 1, in which a heating wire is
located around the double walled conduit.
46. A heat exchange apparatus comprising: a) at least one single
walled conduit defining a first fluid passageway for a first fluid
at a first temperature; and; and b) a drain plate having a drain
plate inlet and a drain plate outlet and a drain plate surface
against which at least a portion of the single wall conduit is
located in intimate contact, the drain plate surface being of
sufficient area to define a second fluid passageway for a second
fluid such that the second fluid flows as a fluid film along the
second fluid passageway so as to effect heat transfer to the first
fluid flowing in the first fluid passageway across the single
walled conduit.
47. A heat exchange apparatus comprising: a) at least one single
walled conduit defining a first fluid passageway for a first fluid
at a first temperature; and; and b) a drain plate having a drain
plate inlet and a drain plate outlet and a drain plate surface
against which at least a portion of the single wall conduit is
located in intimate contact, the drain plate being located
generally orthogonal to the ground, the drain plate surface being
of sufficient area to define a second fluid passageway for a second
fluid such that the second fluid flows as a fluid film along the
second fluid passageway so as to effect heat transfer to the first
fluid flowing in the first fluid passageway across the single
walled conduit.
48.-109. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of and priority to U.S.
Provisional Patent Application Ser. No. 61/229,424, filed on Jul.
29, 2009 and U.S. Provisional Patent Application Ser. No.
61/323,441, filed on Apr. 13, 2010; the contents of each of these
applications are hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present concerns heat exchangers, and more particularly
to single and double-walled heat exchanges.
BACKGROUND
[0003] Heat exchangers are well-known and widely used in a number
of environments to recover thermal energy from fluids. The thermal
energy, if not recovered, would be lost to the environment. Heat
exchangers work by transferring heat from one fluid to another via
a solid wall, which separates the two fluids. This straightforward
principle has been used to recover heat from waste water (so called
"grey water") in, for example, household shower and bath systems. A
number of designs of heat exchangers are described as follows.
[0004] Published U.S. Patent Application No. 2008/0047698 A1
discloses a helical copper fin that is tightly wrapped onto a
single or double wall copper drain pipe and an outer shell that is
made of CPCV or any other suitable material. It is disclosed that
copper is a preferred material because it eliminates differential
expansion effects, while increasing the effective contact area but
acting like a heat fin. One or more parallel helical flow paths,
with or without a variable helix pitch induces turbulence and
mixing, which can also be used to adjust pressure drop. The helical
fin has an outer diameter that is slightly less in the diameter of
the drain pipe into which it can be inserted. This insertion
forcibly ensures metal to metal contact between the fin and the
tube. Fluids that enter the inner helical path cause heat exchange
with a fluid flowing within the outer helix 16 in a counter or coil
flow direction. However, this application does not appear to
disclose a double-walled helical conduit in which cold water flows.
Furthermore, the fins are solid and appear to operate by contacting
a drain pipe and therefore provide heat exchange via the fins.
[0005] U.S. Pat. No. 4,314,397 discloses a solar liquid-to-liquid
heat exchanger. The heat exchanger has a first tubular coil, which
is made of a first heat-conductive tube material. The heat
exchanger also has a second tubular coil that is made of a heat
conductive tube material and is disposed in a tubular arrangement
that is co-axial with the first coil. A cross-sectional view of the
coils shows that a fixing means holds the coils together. The coils
are to be single-walled. The fixing means, which may be solder, may
have a conductive heat transfer coefficient, which is better than
the heat transfer coefficient of the material from which each coil
is made. A number of variations of coil design include an oval
configuration, a rectangular configuration, and a frustoconical
configuration. Solder is used to mechanically connect the coils
together.
[0006] U.S. Pat. No. 4,443,389 discloses a heat exchanger apparatus
in which a cooling tower includes coils that carry heated water
from a facility. The coils include a plurality of tubular designs.
A helical fin is coiled around a central portion within the coil,
which presumably acts as a turbulator. Various other turbulator
structures are illustrated throughout. A tube includes an inner
core appears itself to be a tube; but does not appear to be
immersed in waste grey water. In this patent, cooling fluid flows
through the coils and water is distributed over the coils so as to
enhance heat transfer between the cooling medium on the exterior
surfaces of the coil and heat exchange material flowing through the
coil. The heat exchanger in this case appears to be directed
towards providing cool air to the exterior of the cooling tower.
Thus, air drawn through the louvers is cooled and is expelled from
the apparatus. Both U.S. Pat. Nos. 4,314,397 and 4,443,389 are
directed towards heat exchange applications that are not associated
with recapturing heat from waste grey water.
[0007] Thus, there is a need for an improved heat exchange
apparatus, in which the fluids do not contact each other and which
provides efficient thermal energy transfer across double heat
exchanger walls over a helical or serpentine pathway.
BRIEF SUMMARY
[0008] We have designed a novel passive fluid-to-fluid heat
exchange apparatus, which uses a unique helical or serpentine
double walled conduit to provide unexpectedly high effectiveness in
heat recapture from waste water (also known as "grey water")
commonly found in household shower and bath systems. Furthermore,
we have discovered that single or double walled conduits can be
used against a single drain plate to create a gravity film of grey
water, which caused a surprising increase in heat exchange
properties. The double wall conduits advantageously provide heat
transfer that is the same as single walled conduits even though the
leak path, which is located between the two walls is functional
(i.e. water can pass through the walls at low pressure i.e. less
than 5 psi).
[0009] Accordingly, in one aspect there is provided a heat exchange
apparatus, the apparatus comprising:
[0010] a) at least one double walled conduit having an outer
conduit and an inner conduit located coaxially inside the outer
conduit, and defining a first fluid passageway for a first fluid at
a first temperature; and
[0011] b) a drain defining a second fluid passageway for a second
fluid at a second temperature, the double walled conduit being
located in the drain and downstream of the second fluid flowing
therethrough, such that the second fluid when flowing in the second
fluid passageway effects heat transfer to the first fluid flowing
in the first fluid passageway across the inner and outer
conduits.
[0012] The inner conduit includes an outer wall, the outer conduit
includes an inner wall, the outer wall being located against the
inner wall to define a leak passageway therebetween. The outer
conduit includes an inner knurled surface that is pressed against
the outer wall of the inner conduit to define the leak passageway.
The double walled conduit is helical. The apparatus includes an
outer helical double wall conduit, a central helical double wall
conduit and an inner helical double wall conduit. The outer,
central and inner helical double walled conduits are assembled
concentrically. The circumference of the helices of the double wall
conduits decreases from the outer conduit to the inner conduit. The
helical conduits are coiled in the same direction. The helical
conduits are coiled in a counterclockwise direction. The helical
conduits are coiled in a clockwise direction. Each conduit includes
a bend located at an upper end of the assembled helical conduits.
The first and second fluids flow in a contra-flow manner through
the heat exchange apparatus. The drain is a drain conduit. The
drain conduit includes an upper drain portion connected to a drain
trap. A bypass conduit is connected to the drain conduit, the
bypass conduit having a mesh for blocking particulate material. The
apparatus includes a deflector located in a central core of the
drain conduit. The apparatus includes a vertically orientated
conduit located at the top of the central core of the drain conduit
and having a plurality of holes located therein. A cap is located
on top of the vertically orientated conduit for temporarily
blocking a central bypass channel. The cap is operated manually or
automatically. The deflector is a cone with side plates for forcing
the second fluid away from the conduit. A plurality of helical
conduits are stacked adjacent each other in the drain conduit. The
apparatus includes four stacked helical conduits. The helical
conduits include a common first fluid inlet and a common first
fluid outlet. The apparatus is orientated orthogonal to the ground.
The apparatus is orientated horizontal to the ground. The apparatus
is connected to a drain trap in a shower. The double walled conduit
is serpentine. At least a portion of the serpentine double walled
conduit is located in the drain. At least one serpentine double
wall conduit is connected to an elongate housing having two
sidewalls and passes through an upper set of openings located in
the sidewalls. A first plurality of conduit elbows extend away from
the sidewalls along substantially the entire length of the elongate
housing. A second serpentine double wall conduit is connected to
the elongate housing and passes through a lower set of openings
located in the sidewalls. A second plurality of conduit elbows
extend away from the sidewalls along substantially the entire
length of the elongate housing. A plurality of fins are mounted
around the outer wall of the serpentine conduits, the fins being
disposed parallel to each other and extend substantially the entire
length of the elongate housing. The apparatus includes a turbulator
located in the drain or the helical conduit. The drain is a drain
plate having a drain plate inlet and a drain plate outlet and a
drain plate surface through which at least a portion of the double
wall conduit extends, the drain plate surface being of sufficient
area to define the second fluid passageway for the second fluid
such that the second fluid flows as a fluid film along the second
fluid passageway. A plurality of double walled conduits extend
parallel along the drain plate. The drain plate is orientated
horizontal relative to the ground. The drain is angled relative to
the ground. A plurality of serpentine double walled conduits. The
serpentine conduits are sufficiently spaced apart top allow the
second fluid to flow thereover. The drain is a trench drain. The
first fluid is cold water. The second fluid is grey water. A
heating wire is located inside the double walled conduit. A heating
wire is located around the double walled conduit.
[0013] In another aspect, there is provided a heat exchange
apparatus comprising:
[0014] a) at least one single walled conduit defining a first fluid
passageway for a first fluid at a first temperature; and; and
[0015] b) a drain plate having a drain plate inlet and a drain
plate outlet and a drain plate surface against which at least a
portion of the single wall conduit is located in intimate contact,
the drain plate surface being of sufficient area to define a second
fluid passageway for a second fluid such that the second fluid
flows as a fluid film along the second fluid passageway so as to
effect heat transfer to the first fluid flowing in the first fluid
passageway across the single walled conduit.
[0016] In another aspect, there is provided a heat exchange
apparatus comprising:
[0017] a) at least one single walled conduit defining a first fluid
passageway for a first fluid at a first temperature; and; and
[0018] b) a drain plate having a drain plate inlet and a drain
plate outlet and a drain plate surface against which at least a
portion of the single wall conduit is located in intimate contact,
the drain plate being located generally orthogonal to the ground,
the drain plate surface being of sufficient area to define a second
fluid passageway for a second fluid such that the second fluid
flows as a fluid film along the second fluid passageway so as to
effect heat transfer to the first fluid flowing in the first fluid
passageway across the single walled conduit.
[0019] In another aspect, there is provided a heat exchange
apparatus comprising:
[0020] a) at least one single walled conduit defining a first fluid
passageway for a first fluid at a first temperature; and
[0021] b) a drain plate having a drain plate inlet and a drain
plate outlet and a drain plate surface against which at least a
portion of the single wall conduit is located in intimate contact,
the drain plate being located generally orthogonal to the ground,
the drain plate surface being of sufficient area to define a second
fluid passageway for a second fluid, the drain plate being angled
relative to the ground, such that the second fluid flows as a fluid
film along the angled second fluid passageway so as to effect heat
transfer to the first fluid flowing in the first fluid passageway
across the single walled conduit.
[0022] In another aspect, there is provided a heat exchange
apparatus comprising:
[0023] a) at least one single walled conduit defining a first fluid
passageway for a first fluid at a first temperature; and; and
[0024] b) a drain plate having a drain plate inlet and a drain
plate outlet and a drain plate surface against which at least a
portion of the single wall conduit is located in intimate contact,
the drain plate being located generally horizontal relative to the
ground, the drain plate surface being of sufficient area to define
a second fluid passageway for a second fluid such that the second
fluid flows as a fluid film along the second fluid passageway so as
to effect heat transfer to the first fluid flowing in the first
fluid passageway across the single walled conduit.
[0025] The first and second fluids flow in a contra-flow manner
through the heat exchange apparatus. The apparatus is connected to
a drain trap in a shower. The single walled conduit is serpentine.
At least one serpentine double wall conduit is connected to an
elongate housing having two sidewalls and passes through an upper
set of openings located in the sidewalls. A first plurality of
conduit elbows extend away from the sidewalls along substantially
the entire length of the elongate housing. A second serpentine
single walled conduit is connected to the elongate housing and
passes through a lower set of openings located in the sidewalls. A
second plurality of conduit elbows extend away from the sidewalls
along substantially the entire length of the elongate housing. A
plurality of fins are mounted around the outer wall of the
serpentine conduits, the fins being disposed parallel to each other
and extend substantially the entire length of the elongate housing.
The apparatus includes a turbulator located in the conduit. A
plurality of single walled conduits extends parallel along the
drain plate. The serpentine conduits are sufficiently spaced apart
to allow the second fluid to flow thereover. The drain is a trench
drain. The first fluid is cold water. The second fluid is grey
water. A heating wire is located inside the single walled conduit.
A heating wire is located around the single walled conduit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] These and other features of that described herein will
become more apparent from the following description in which
reference is made to the appended drawings wherein:
[0027] FIG. 1 is a schematic view of a household shower/bath system
showing the location of a heat exchanger;
[0028] FIG. 2 is a perspective view of a vertical helical heat
exchange apparatus located below a drain trap
[0029] FIG. 3 is a perspective view of the heat exchanger of FIG. 2
showing three helical cold water conduits;
[0030] FIG. 3A is a perspective cross sectional view taken along
line 3-3' in FIG. 3;
[0031] FIG. 4 is a side view of FIG. 3A showing the double wall
feature of the helical conduits;
[0032] FIG. 4A is a cross sectional view of a double walled
conduit;
[0033] FIG. 5 is a perspective view of the helical heat exchange
apparatus of FIG. 2 showing the relative location of the three
helical conduits;
[0034] FIG. 6 is an exploded perspective view of the heat exchange
apparatus of FIG. 2 showing the three helical conduits;
[0035] FIG. 6A is a perspective view of a heat exchange apparatus
showing conduit bends;
[0036] FIG. 6B is a perspective view of an alternative vertical
heat exchange apparatus;
[0037] FIG. 6C is a perspective exploded view of the apparatus of
FIG. 6B;
[0038] FIG. 6D is a perspective view of a plurality of stacked
helical double walled conduits;
[0039] FIG. 7A is a schematic representation of an anti blocking
feature showing a bypass conduit;
[0040] FIG. 7B is a schematic representation of another
anti-blocking feature showing an elongate pipe with a plurality of
holes;
[0041] FIG. 7C is a schematic representation of another
anti-blocking feature showing a cap and mesh;
[0042] FIG. 7D is a schematic representation of another
anti-blocking feature showing a deflector;
[0043] FIG. 7E is a top view of the deflector of FIG. 7D;
[0044] FIG. 8 is a perspective view of a horizontal heat
exchanger;
[0045] FIG. 8A is a cross sectional view taken along line 8-8'
showing the location of fins and two serpentine conduits;
[0046] FIG. 9 is a perspective detailed view of a portion of the
heat exchanger of FIG. 8 showing details of the serpentine conduits
and fins;
[0047] FIG. 9A is a perspective partial cutaway view of FIG. 9
showing the location of holes and the respective serpentine
conduits;
[0048] FIGS. 10A-C are diagrammatic representation of a number of
surface turbulation patterns;
[0049] FIGS. 11A-G are diagrammatic representations of a number of
turbulator inserts;
[0050] FIGS. 12A-E are diagrammatic representations of a number of
grey water inserts;
[0051] FIG. 13 is a perspective view of a film heat exchanger
apparatus;
[0052] FIG. 14 are perspective partial cutaway views of the film
heat exchange apparatus of FIG. 13 showing the location of the cold
water conduits;
[0053] FIG. 15 is a detailed view of an end portion of the film
heat exchange apparatus of FIG. 13 showing the location of the cold
water conduits and the drain plate;
[0054] FIG. 15A is a perspective view of a shell of a horizontal
heat exchange apparatus;
[0055] FIG. 15B is a perspective view of serpentine conduits
located inside the apparatus of FIG. 15A;
[0056] FIG. 16 is a top view of an alternative film heat exchange
apparatus showing the location of the cold water conduits;
[0057] FIG. 16A is a cross sectional view of the cold water
conduits of FIG. 16;
[0058] FIG. 17A is an exploded view of a manifold showing the
location of the double wall conduit in the manifold;
[0059] FIG. 17B is a detailed view of the manifold of FIG. 17A
showing the conduit located in the manifold;
[0060] FIG. 18 is a schematic representation of a gravity
thermosyphon for use with any heat exchange apparatus described
herein;
[0061] FIG. 19 is a front view of an alternative heat exchange
apparatus disposed in a vertical orientation;
[0062] FIG. 20 is a schematic representation of the heat exchange
apparatus of FIG. 19 showing the location of the cold water
conduits adjacent a drain plate; and
[0063] FIG. 21 is a perspective view of a heat exchange apparatus
located in a trench drain.
DETAILED DESCRIPTION
Definitions
[0064] Unless otherwise specified, the following definitions
apply:
[0065] The singular forms "a", "an" and "the" include corresponding
plural references unless the context clearly dictates
otherwise.
[0066] As used herein, the term "comprising" is intended to mean
that the list of elements following the word "comprising" are
required or mandatory but that other elements are optional and may
or may not be present.
[0067] As used herein, the term "consisting of" is intended to mean
including and limited to whatever follows the phrase "consisting
of". Thus, the phrase "consisting of" indicates that the listed
elements are required or mandatory and that no other elements may
be present.
[0068] As used herein, the term "turbulator" when referring to
either a surface or to an insert having a surface that acts as a
turbulator, is intended to mean that the surface has a plurality of
projections extending away from the surface. Surface turbulators
and inserted turbulators are used to increase convection rates and
heat transfer coefficients at heat exchange surfaces in fluid
passageways in order to provide high performance in compact heat
exchange assemblies, and to orientate fluids into a pre-defined
direction often resulting in chaotic paths. Examples of types of
turbulators include, but are not limited to, corrugations, peaks
and troughs, nubbins, raised chevrons having a gap between, fish
scales, raised zigzag moldings, meshes, criss cross oriented wires,
porous materials, and the like. Turbulators may comprise uniform or
non-uniform surface profiles, textures, open cell structures, and
shapes. Fluid passageway geometry allows control of fluid flow via
solid or semi-solid mechanical structures and may be constructed
from laminate composites, molded parts, and meshes of plastics,
ceramics, metals or other materials.
[0069] As used herein the term "fluid" is intended to mean gas or
liquid. Examples of liquids suitable for use with the heat
exchangers described herein include, but are not limited to, water,
hydraulic fluid, petroleum, glycol, oil and the like, and
steam.
[0070] Referring now to FIG. 1, a heat exchange apparatus is shown
generally at 10 in use with a household shower and bath system 12.
The household shower and bath system 12 includes a water heater 14,
a hot water line 16, a cold water line 18, a warm water line 20, a
mixing valve 22, a shower head 24 and a drain trap 26. The hot and
warm water lines 16, 20 are each connected to the mixing valve 22,
the temperature of the water exiting the shower head 24 being
controlled by the user operating the mixing valve 22. The cold
water line 18 is connected to the heat exchange apparatus 10 and
feeds cold water 25 (a first fluid) into the apparatus 10. The warm
water line 20 is connected to the heat exchange apparatus 10 and
the mixing valve 22. The drain trap 26 receives drain water 28 (so
called "grey water") (a second fluid) from the shower/bath tub and
communicates the drain water to the heat exchange apparatus 10.
After flowing through the heat exchange apparatus 10, the grey
water 28 exits the household shower system 12 to a main drain (not
shown). It should be noted that although an example of a household
shower/bath system is illustrated, the heat exchange apparatus
described may also be used for other applications that require heat
exchange between two fluids. Furthermore, it is to be noted that
any of the heat exchangers described hereinbelow can also be
connected to the system 12, either directly to the drain trap 26 or
downstream of the P-trap.
I. Helical Double Walled Heat Exchange Apparatus
[0071] Referring now to FIGS. 2, 3, 3A, 4 and 4A, a helical (or
coiled) double wall heat exchange apparatus is shown generally at
10. The apparatus 10 is for use in household applications and can
be connected to the drain trap 26 in a typical household shower,
bath or sink. The apparatus 10 may also be used for industrial or
commercial applications in which high volumes of waste grey water
are used. Advantageously, the apparatus provides thermal energy
recapture of about 80% in a heat exchanger with a vertical height
of 20-inches and a nominal inner diameter 3-inches with pressure
loss below 5 psi at 10 litres per minute flow. By contrast, a
Delstar mesh vertical heat exchanger has an effectiveness in the
range of 70% for a heat exchanger of 72-inches with comparable
pressure loss. The apparatus 10 is typically used in the vertical
orientation, i.e. is orthogonally disposed to the ground. The
apparatus 10 comprises at least one helical double wall conduit 30
and a drain conduit 32. The helical double wall conduit 30 is a
first fluid passageway 34 for the first fluid 25, typically cold
water, at a first temperature, typically about 10.degree. C. The
helical double wall conduit 30 includes an outer conduit 36 and an
inner conduit 38 located coaxially inside the outer conduit 36,
which define the first fluid passageway 34. The drain conduit 32
defines a second fluid passageway 40 for the second fluid 28,
typically grey water, at a second temperature, typically about
40.degree. C. The drain conduit 32 includes an upper drain portion,
which is connected to the drain trap 26 such that grey water flows
from the shower into the drain conduit 32. The helical double
walled conduit 30 is located in the drain conduit 32 and downstream
of the second fluid 28 flowing therethrough. The second fluid 28
when it flows in the second fluid passageway 40 effects thermal
energy (heat) transfer to the first fluid 25 flowing in the first
fluid passageway 34 across the inner conduit 38 and the outer
conduit 36.
[0072] Referring to FIG. 4A, the inner conduit 38 includes an outer
wall 42, the outer conduit 36 includes an inner wall 44, the outer
wall 42 being located against the inner wall 44 to define a leak
passageway 46 therebetween, which can vent to the atmosphere if
either of the inner or outer walls 42, 44 ruptures or is pierced.
In one example, the outer conduit 36 includes an inner knurled
surface that is pressed against the outer wall 42 of the inner
conduit 38 to define the leak passageway 46. In another example,
the inner wall 44 of the outer conduit 36 is smooth and is pressed
against the outer wall 36 of the inner conduit 38 with sufficient
force to leave a leak passageway 46 therebetween.
[0073] Cross-connection of plumbing devices is ruled by strict, but
variable, local regulations, where grey water and fresh cold water
are present within the same heat exchange apparatus. Thus, a double
wall design is desirable over any other protection means to prevent
fresh water contamination by grey water in the event of system
failure, such as if the heat exchanger wall is ruptured or
pierced.
[0074] As best illustrated in FIGS. 3, 5 and 6, the heat exchange
apparatus 10 includes three helical double wall conduits 30A, 30B
and 30C, the outer helical double wall conduit 30A, the central
helical double wall conduit 30B and the inner helical double wall
conduit 30C, which are assembled concentrically within an outer
wall 29 and an inner wall 27 of the drain conduit. The
circumference of the helices of the double wall conduits 30A, 30B
and 30C decreases from the outer conduit 30A to the inner conduit
30C. The helical conduits 30A, 30B and 30C are located in the drain
conduit 32 and assembled concentrically, yet are sufficiently
spaced apart to define the second fluid passageway through which
the grey water can flow. Each of the helical conduits 30A, 30B and
30C are coaxially orientated and are coiled in the same direction.
In the examples illustrated, the helical turns in conduits 30A, 30B
and 30C are coiled in a counterclockwise direction. However, one
skilled in the art will recognize that the helical coils can also
turn in a clockwise direction. Thus, waste grey water flowing along
the second fluid passageway contacts the outer surfaces of the
helical coils 30A, 30B and 30C, which act as thermal energy
exchange surfaces, as it moves along the second fluid passageway
and is able to efficiently transfer its thermal energy across the
double wall of the helical conduits to the first fluid flowing in
the first fluid passageway. It is also possible that instead of the
helices 30A. 30B, and 30C being concentrically assembled, they may
also be located offset from each other. Optionally, a low voltage
heating wire, heating coil or heating tape (not shown) may be
located inside the conduits 30A, 30B, and 30C. This provides not
only turbulation of the cold water, but also provides additional
heat so that the heat exchanger 10 can provide all the heat
required for the application (i.e. no longer passive and does not
need to be combined with an external heating system).
[0075] Referring now to FIG. 6A, the heat exchange apparatus 10 may
have additional features such as a plurality of bends 31 located at
the upper end of the assembled conduits. Each bend 31 is connected
to a double walled conduit. The bends 31 are made in each conduit
before assembly and then the conduit is coiled to create two
helices, one on top of the other. It is not the same as a double
helix, which has two helices made from one conduit, but the helices
are on two separate diameters. Advantageously, the location of the
bends 31 allows the cold water connectors 33,35 to be located
either at the top of the apparatus 10 or the bottom, which is
useful in applications where the apparatus 10 is to be located in a
space-restricted area. In one example, the first and second fluids
flow in a contra-flow manner through the heat exchange apparatus
10. It is also possible to have the fluids flow in a parallel flow
manner. A first temperature T1 of the first fluid 25 entering the
first fluid passageway 34 is typically less than the second
temperature T2 of the first fluid 25 as it exits the first fluid
passageway 34. Similarly, the third temperature T3 of the second
fluid 28 entering the second fluid passageway 40 is greater than
the fourth temperature T4 of the second fluid 28 as it exits the
second fluid passageway 40. By way of example, T1 is typically
10.degree. C. for cold water, T3 is typically 40.degree. C. for
grey water and T4 is typically 30.degree. C. for grey water exiting
the heat exchanger 10, and T2 is typically 24.degree. C. for warmed
water entering the warm water line 22 from the heat exchanger 10.
To measure the effectiveness of the heat exchange apparatus, the
following equation is used:
Effectiveness = T cold out - T cold in T grey in - T cold in
##EQU00001##
[0076] where T denotes temperature in .degree. C.
[0077] At least one of the fluids flows through its respective
passageway under pressure, the other fluid flowing through its
respective passageway at atmospheric pressure. Typically, the
second fluid (the cold water) flows under pressure at approximately
50 psi along the first fluid passageway 34.
[0078] Referring to FIGS. 6B, 6C and 6D, an alternative embodiment
of a vertical heat exchange apparatus is shown generally at 60. The
apparatus 60 comprises an outer shell 62, a grey water inlet 64, a
grey water outlet 66, a cold water inlet 68 and a cold water outlet
70. An inner shell 72 houses a plurality of helical double wall
conduits 74, which are stacked adjacent each other (in the example
illustrated four conduits are provided). The conduits 74 each
receive cold water from the common cold water inlet 68 and the
warmed water exits the heat exchanger via the common outlet 70. The
multiple stacked helices provide for heat exchange with reduced
pressure loss compared to a single helix of the same height.
[0079] Referring to FIGS. 7A through 7E, illustrate a number of
features, which may be added to the vertical helical double wall
heat exchange apparatus to prevent blocking of the heat exchanger.
Although the features are used primarily for sinks, they may also
be used in other applications. FIG. 7A illustrates a bypass conduit
40 connected to the drain conduit, which includes a mesh 42 that
blocks large particulate material from entering the heat exchanger
10. The mesh 42 forces the particulates into the bypass conduit 40.
An optional deflector or blocker 44 may be located in the central
core of the drain conduit. FIG. 7B illustrates a length of vertical
orientated conduit 46 located at the top of the core of the drain
conduit 32 and includes a plurality of holes 48. Grey water passes
through the holes 48 to the exchanger 10. Particulate or larger
debris is prevented from entering the exchanger and so passes down
the drain conduit centre 49. FIG. 7C illustrates a cap 50, which
blocks a center bypass channel 52. When the cap 50 is closed, grey
water is forced to the sides where it falls onto vertically
disposed helical double walled conduits 30. Optionally, the sides
can have a mesh 51. The cap 50 can be operated manually or
automatically. The cap 50 can be a twist cap, a magnetic plug, or
powered by motor or hydraulic action. Referring to FIG. 7D
illustrates a deflector 54, which forces all particulate matter to
the sides of the heat exchanger 10. The deflector 54 is located
such that there is always adequate clearance so that any material
that moves through the top will fit around exchanger, after being
forced to the sides. FIG. 7E illustrates a top view of the
deflector 54. The deflector 54 is a cone with side plates 56. The
cone forces water away from the conduit onto side plates 56, which
drop then, falls onto the exchanger. A gap 58 between each side
plate 56 is sufficiently large such that any material that fits
through exchanger opening will fit through gap 58.
II. Serpentine Double Walled Heat Exchanger
[0080] Referring now to FIGS. 8, 8A, 9, and 9A, an alternative heat
exchange apparatus 100 is illustrated. The heat exchange apparatus
100 comprises an elongate housing 102 having a housing inlet 104
and a housing outlet 106. The housing inlet 104 is connected to the
drain trap 26 (not shown) or may be located anywhere downstream of
the drain and defines the first fluid passageway for the first
fluid, typically grey water. Typically, the heat exchange apparatus
100 is orientated horizontal relative to the ground so that the
apparatus 100 can be located under, for example, the shower base.
The elongate housing 102 includes two sidewalls 108 having a
plurality of openings 110 therein. The openings 110 are arranged in
groups of two along the sidewalls 108 and include an upper set 112
and a lower set 114. The lower set 114 are staggered away from the
upper set 112, although it is possible that the upper and lower
sets 112 and 114 can be located collinear with each other.
[0081] Referring to FIGS. 7, 7A and 8, at least one serpentine
double wall conduit 116 is connected to the elongate housing 102
and passes through the upper set 112 of openings 110. A first
plurality of conduit elbows 118 extend away from the sidewalls 108
along substantially the entire length of the elongate housing 102.
A second serpentine double wall conduit 120 is connected to the
elongate housing 102 and passes through the lower set 114 of
openings 110. A second plurality of conduit elbows 122 extend away
from the sidewalls 108 along substantially the entire length of the
elongate housing 102. Additional serpentine double wall conduits
can be used depending upon the application that is contemplated by
the user. In the examples illustrated, a substantial portion of the
serpentine conduits 116, 120 is located inside the elongate housing
102 and is thus able to contact the grey water, which flows through
the housing 102. It is also possible that all of the serpentine
conduits 116, 120 are located inside the elongate housing, thereby
eliminating the conduit elbows exterior of the housing. This
example is useful in applications where a more streamlined heat
exchange apparatus is needed in, for example, space restricted
locations.
[0082] Referring now to FIG. 8A, a plurality of fins 124, which may
be corrugated along their surface, are mounted around the outer
wall of the serpentine conduits 116, 120. The fins 124 are disposed
parallel to each other and extend substantially the entire length
of the elongate housing 102. The serpentine conduits 116, 120 and
the fins 124 are located in the lower portion of the housing 102
such that they define a gap 126 thereabove of sufficient size to
allow the use of cleaning tools or inspection of the apparatus
during routine maintenance. A cap 128 is mounted over the elongate
housing 102, which can be easily removed to expose the serpentine
conduits 116, 120 and the fins 124. For ease of illustration, the
openings 110 described are shown in the outer fin 124 and
correspond to the openings in the adjacent sidewall 108.
[0083] Optionally, a low voltage heating wire, heating coil or
heating tape (not shown) may be located inside the conduit 116. The
heating wire may serve to increase turbulence (see below) of the
cold water flowing in the conduit and/or increase the cold water
temperature so that the heat exchanger 100 can provide all the heat
required for the application (i.e. no longer passive and does not
need to be combined with an external heating system). As described
above in the heat exchange apparatus 10, a ventable leak passageway
is located between the inner and outer conduits. The grey water
when it flows along the second fluid passageway contacts the
serpentine conduits 116, 120 and the fins 124 to effect heat
transfer to the cold water fluid flowing in the serpentine conduits
116, 120 across their respective outer and inner conduit walls.
III. Turbulators
[0084] Referring now to FIGS. 10A through 100 and FIGS. 11A through
110, the drain conduit 32, the helical conduits 30A, 30B and 30C,
and the serpentine conduits 116, 120 can be used with or without
turbulators of the type known in the art. In particular, as seen in
FIG. 10A, all or a portion of the inner wall of the conduits may
have grooves, which enhance cold water turbulence. Also, as seen in
FIGS. 10B and 100, corrugated or spiral conduits may also enhance
the thermal energy transfer surfaces of the drain conduit.
Turbulator inserts, as seen in FIG. 11A through G, known to those
skilled in the art may also be used to enhance thermal energy
transfer. FIGS. 11A through C illustrate examples of the turbulator
inserts that include a twisted plastic or sheet materials with
variable pitch. The greater the pitch, the more turbulence, more
pressure loss and therefore higher heat transfer. Surface patterns
such as herringbone or straight patterns may also be added to the
inserts, as seen in FIGS. 11B and C. Twisted wire turbulators or
rope as seen in Figure D, whereas a mixing nozzle insert for use at
a nozzle entry located in the cold water conduit are also useful,
as seen in FIGS. 11E and F. FIG. 11G is another type of turbulator
design, which is manufactured by Statomix.TM.. Additional
turbulator designs are also useful for location in the grey water
passageway is illustrated in FIG. 12A through C. In one example,
FIG. 12A, fins are located exterior of the cold water conduit and
project into the grey water passageway to cause turbulation of the
grey water. FIG. 12B is an insert, which can be located inside the
grey water passageway and may include holes through which the cold
water serpentine or helical conduits can pass. The insert includes
a surface pattern, which causes turbulation of the grey water. FIG.
12C is a torpedo-shaped insert, which may be located in the grey
water passageway to effect turbulation of the grey water. FIG. 12D
is a helical double wall torpedo insert, which when located in the
grey water passageway causes turbulation of the grey water. The
configuration of the torpedo-shaped inserts simulates grey water
movement in a direction orthogonal to the ground.
[0085] As illustrated in FIG. 12E, a turbulator that is
manufactured by Koflo is available in short lengths for purpose of
mixing fluids. It is possible to manufacture a longer version of
this for creating turbulence in cold water in our heat exchangers.
The turbulator includes a plurality of half circles connected in a
X pattern at each centre of the half circle. This design forces
water to mix in two directions, i.e. left handed and right handed
competing threads.
[0086] The flow of fluids can be passive, i.e. by gravity or can
flow under the influence of pressure, either above or below
atmospheric pressure. The heat exchange apparatus described herein
are also self-draining. Moreover, due to their design, the helical
can be located directly in a grey water pathway with or without the
use of pre-filtration to remove particulate debris. Additional clog
reduction features may include hair deflectors, non-stick coatings
on the thermal transfer surfaces, or, in the case of the fins 126,
the fins may have polished knife edges.
[0087] In one example, grey water flows over the three helical
conduits, by gravity, such that it exchanges its heat (typically
about 40.degree. C.) to the source of cold water flowing through
the conduits located in intimate contact with the drain conduit. In
certain examples, higher fluid temperatures (>100.degree. C.)
may be used to also exchange thermal energy to cold water so as to
generate steam. The heat exchange takes place across a thin
(typically from about 1/1000 inch to about 1/5 inch thickness)
double wall arrangement. The cold water flowing in the first cold
water passageway is heated to produce warmed water, which may then
be stored in a storage tank or communicated to a mixing valve in a
shower or bath system. Advantageously, the heat exchange apparatus
is constructed from inexpensive materials and when installed is
essentially maintenance-free. The grey water conduits (pipes) used
are standard 1.5 to 4 inch and are universally retrofittable into
existing plumbing systems with the minimum of disruption to the
household.
[0088] At least one of the thermal transfer surfaces is uneven. In
one example, one thermal transfer surface is corrugated and defines
a plurality of fin-like peaks (or blades) and troughs that extend
longitudinally along the channel member 30 between the first and
second end portions.
IV: Film Heat Exchanger
[0089] Referring now to FIGS. 13, 14 and 15, an alternative heat
exchange apparatus is shown generally at 200. The heat exchange
apparatus 200 is for applications that typically require the heat
exchange apparatus to be located horizontal to the ground. The heat
exchange apparatus 200 comprises an elongate housing 201 having an
outer shell 202, a drain plate inlet 204, a drain plate outlet 206
and a drain plate 208. The drain plate inlet 204 can be connected
to the drain trap 26, as described above. A plurality of double
walled conduits 210 extend in parallel along the drain plate 208. A
plurality of conduit inlets 212 are located at one end of the drain
plate 208 and a plurality of conduit outlets 214 are located at
another end of the drain plate 208 The conduits 210 are double
walled as described above for the heat exchange apparatus 10 and
100. The conduits 210 define the first fluid passageway for the
cold water. The drain plate 208 has a drain plate surface 216
through which at least a portion of the double wall conduits 210
extend. The drain plate surface 216 is of sufficiently large area
to define the second fluid passageway for the second fluid such
that the second fluid flows as a fluid film along the second fluid
passageway and effects heat transfer to the first fluid flowing in
the first fluid passageway across the inner and outer conduits of
the conduits 210.
[0090] The drain plate 208 may be angled to provide a slope along
the sides of the plate at the front end and a raised portion at the
back end so as to force the grey water towards the conduits located
at the extreme edges of the drain plate, and yet maintains the
ability of the heat exchanger to self drain.
[0091] Another example the heat exchange apparatus 200 is shown in
FIGS. 15A, 15B, 16 and 16A in which a plurality of serpentine
conduits 210A, 210B, 210C and 210D are fully located inside the
elongate housing 201 and are located close to each other, yet with
a space between each conduit to allow waste grey water to flow
thereover. The drain plate surface 216 is sufficiently large to
create a thin film of grey water as described above. The elongate
housing 201 is located inside a shell 203, which includes a gradual
entry, and gradual exit which reduces clogging risk.
[0092] The heat exchange apparatus 200 can be made using plates
that are die formed such that they create the same flow path as if
in conduits. The double wall plates with serpentine flow paths can
then be formed and welded to create a vertical cylinder as another
construction for the vertical helical heat exchanger 10.
Additionally, the same plates can also be made using a thermally
conductive injection moulded plastic.
[0093] The horizontal film heat exchanger 200 can be located
underneath a shower floor having a false drain, which lead to the
true drain. Alternatively, the drain plate is located on the floor
of the shower and is able to directly capture heat from grey water
as it flows thereover. Additionally, the heat exchanger 200 may be
incorporated directly into either a dishwasher or a washing machine
or any other appliance, which uses hot water.
[0094] Built-in options may be included within any of the heat
exchange apparatuses described herein in order to increase overall
system performance and durability. These options include thin wall
elements; laminar flow disruptor elements; check valve systems; one
or more external level indicators; anti scaling capabilities such
as, for example, mechanical devices and passage configurations to
reduce scaling, anti-scaling coatings, vibration, chemical, and
electrical means; anti corrosion means such as, for example,
electrical, chemical, anodic, cathodic, and coatings; and water
hammer protection such as, for example, shock absorbers, flexible
or relatively soft and elastic cold water circuit components.
Additional features may include use of an insulating shell on the
systems and subsystems. System leaks and malfunctions can be
detected in a variety of ways using, for example, relative flow
measurement and/or pressure transducers and gauges located at
strategic points in the heat exchange apparatus. The heat
exchangers may be self draining in both horizontal and vertical
positions. If electric power is required for monitoring or control
equipment, power sources such as batteries, thermoelectric, or
micro-turbines can be advantageously used in combination or
alone.
[0095] It is known that greater thermal transfer performance and
ease of manufacturing are obtained by using a thin formed sheet
material in the manufacturing process of the heat exchanger
components. Using thin wall stainless steel composite sheets of
approximately 0.015'' to 0.035'' thicknesses in heat exchanger
apparatuses provides low resistance to burst due to possible
excessive high internal cold water pressure, such as those commonly
used in household or industrial plumbing systems.
[0096] The aforesaid heat exchangers can be used in many
applications such as for example in household shower/baths, in
washing machines and the like. In the design for use in household
shower, grey water typically drains at 10 litres/hour.
[0097] Advantageously, the serpentine conduits described for heat
exchanger 100 and 200 (FIGS. 16 and 16A) increase the dwell time of
cold water in contact with the grey water. This is in contrast with
elongate conduits and the bends outside the grey water. Thus, cold
water conduit bends are located inside the grey water passageway so
that the dwell time is increased and cold water never leaves the
heat transfer area while inside the exchanger.
V. Manifolds
[0098] Referring now to FIGS. 17A and 17B, a manifold 300 is
illustrated which provides double wall leak off and can be used to
mount and secure the double wall conduits 210 of any of the heat
exchange apparatuses described herein to the respective
apparatuses. The manifold 300 comprises an outer conduit connector
302, an inner conduit connector 304 and a flow director 306. The
connectors 302, 304 include openings 308 for receiving the double
wall conduits 210 therein. The outer conduit connector 302 and the
inner conduit connector 304 include knurled surfaces 309, which
provide a double wall leak passageway 310 through which cold water
can flow in the event that the integrity of the double wall conduit
is compromised. The manifold 300 may be a double manifold located
at either end of heat exchange apparatus and may be for single or
multiple circuits of conduits. Additionally, cold water can flow
into and out of the same manifold or in an independent
manifold.
VI. Gravity Thermosyphon
[0099] Referring now to FIG. 18, a gravity thermosyphon 400 is
contemplated for use with the heat exchange apparatuses as
described herein. The thermosyphon 400 comprises a bath 402 of
refrigerant material such as ethylene glycol in which the second
fluid passageway carrying the grey water is located. Located above
the second fluid passageway 40 are the double walled conduits, such
as for example, the conduits 210 such as those described herein. A
deflector 403 may be located between the conduits 210 and the
second fluid passageway (the grey water passageway) 40. The grey
water flowing along the second fluid passageway 40 causes the
refrigerant to heat up and evaporate (see wavy lines). The
evaporated refrigerant 405 contacts the double wall conduits 210
carrying the cold water 25, which flows into the conduits 210 at a
first end 404. The vaporized refrigerant 405 condenses on contact
with the cold conduits 210 and returns to the bath 402. The thermal
energy from the vaporized refrigerant thermally transfers to the
cold water so that it exits the conduit 210 at a second end 406 at
a higher temperature. The process repeats so long as the grey water
and the cold water flow in their respective passageways.
VII: Alternative Film Heat Exchanger
[0100] Referring now to FIGS. 19 and 20, an alternative embodiment
of a heat exchange apparatus is shown generally at 500. The heat
exchange apparatus 500 comprise one or more single or double walled
conduits 502, as described herein, which define a first fluid
passageway 504 for a first fluid at a first temperature. A drain
plate 506 having a drain plate inlet 508 and a drain plate outlet
510 and a drain plate surface 512 is located either generally
orthogonal to the ground, generally horizontal to the ground or
angled relative to the ground to create an incline. A portion of
the single or double walled conduits 502 is located in intimate
contact with the drain plate 506, which has a surface of sufficient
area to define a second fluid passageway 514 along which the grey
water flows by gravity. The location of the conduits 502 against
the drain plate 506 provides a passageway of the grey water which
flows as a film 516 over the conduits 502 to efficiently effect
heat transfer to the first fluid flowing in the first fluid
passageway across the single or double walled conduits 502. The
drain plate inlet 508, as best illustrated in FIG. 20, is connected
to an outer shell 520, which is located over the conduits 502. The
drain inlet 508 is shaped to force the grey water along a deviated
path 518 towards the conduits 502 to create the film 516
thereagainst thereby effecting heat transfer across the wall or
walls of the conduits 502. Thus, heat exchange occurs on only one
side of the apparatus. Furthermore, the width of the drain plate
506 is larger than the width of the feed pipe (not shown) so as to
create the film 516, which flows along the second fluid passageway.
As above, turbulators can be used inside the cold water passageway
to increase heat exchange. The surfaces of the heat exchange
apparatus 500 can be coated with a non-stick coating such as TEFLON
to prevent fouling by debris.
[0101] As best illustrated in FIG. 21, any one of the heat exchange
apparatus described herein can be located in a trench drain 520.
Common manifolds 522 and 524 are connected to their respective cold
water inlets and warmed water outlets. In the example illustrated,
grey water enters the trench drain 520 and passes downwardly over
the conduits and effects heat exchange. For most applications, the
width of the trench drain is about 12-inches, whereas the height is
about 8-inches. The train drain 520 is open, which advantageously
allows ease of installation of the heat exchanger and ease of
maintenance.
[0102] A hybrid water heater may be used in combination with any of
the above described heat exchangers by using electric heating
elements or wires directly in the cold water conduits or by
wrapping a heating coil around the outside of the conduits. This
can be combined with a solar panel to make a low cost solar water
heater. It can be low voltage to avoid the risk of electric shock.
Electric heaters have very high efficiency because almost all of
the electrical energy is converted into heat, which heats the
water. Tankless electric heaters often cannot supply enough
capacity of hot water because of either the size of the heater that
would be required or the power. However, a hybrid system, which
combines a heat exchanger with a heating element to provide more
heating capacity, may advantageously replace a standard water
heater.
Other Embodiments
[0103] It is understood that the examples and embodiments described
herein are for illustrative purposes only and that various
modifications or changes in light thereof will be suggested to
persons skilled in the art and are to be included within the
present discovery and scope of the appended claims.
* * * * *