Note: Descriptions are shown in the official language in which they were submitted.
WASTE HEAT EXCHANGER WITH THERMAL STORAGE
DESCRIPTION
FIELD OF THE INVENTION
The field is heat exchangers that save energy by heat exchange between a fresh
liquid and
waste fluids.
BACKGROUND OF THE INVENTION
Current drainpipe heat exchangers only work in the 'continuous flow mode' when
fresh
water is being used and drained so both flow through the exchanger at the same
time. They
don't work in 'batch flow mode' where fresh water is used and drained
separately, such as in
wash machines, tubs, clothes dryers, furnace exhausts and the like. This is
because they can't
store heat between the fill-drain cycles. The instant invention uses a tank of
the fresh water to
overcome this problem and is thereby able to exchange more heat with the fresh
water.
Therefore a great deal of heat energy continues to be wasted adding to global
warming and
pollution.
Hygienic hot water is unique in that, in any given time zone, its use peaks at
certain
narrow times-of-day: morning, mid-day and evening at which times millions of
water heaters
are 'on' all together until 'turn off' temperature is reached. Heated
electrically requires
expensive peak power and related transmission losses and. If heated with fuel,
the heaters
simultaneously release huge volumes of moist acidic exhaust fumes that form
unhealthy
smog in cities and environmental degradation.
With the instant invention, heaters turn 'off' faster resulting in fewer being
'on' together
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which lowers those negatives.
SUMMARY OF THE INVENTION
Using hot water as the example, the instant apparatus preferentially heats
fresh cold water
with waste fluid no matter their temperature. The apparatus has a water tank
pressurized with
the fresh water and an outlet connected to a water dispenser such as a water
heater or
faucet(s). Passing through and sealed to the ends of the tank is a tubular
plastic housing with
a central drainpipe connected into a building's drainage and/or venting
system. Drainpipe can
have a surrounding slit sleeve for double-wall safety.
A compressible gasket between drainpipe and housing creates an annular water
conduit.
One end of the housing extends past the tank and has a cold water inlet to the
conduit.
To only heat the tank water or said otherwise, to preferentially temper it,
the conduit has a
rows of holes into the tank which are opened or closed by flap valves which
move by the
force or current of convection, also called mass transfer. Convection in any
fluid results from
changes in density, in this case, between tank water and conduit water. A
warmer drainpipe
heats and lowers water density in the conduit. Colder denser tank water pushes
valves open
to enter conduit, get heated by the drainpipe/sleeve rise upwards into tank. A
colder drainpipe
densifies conduit water which closes the valves to prevent it escaping into-
and cooling the
tank thereby providing preferential tempering. During continuous flows the
valves are closed
by forced convection flow through the conduit forcing the incoming water to
travel the full
length of the warmer drainpipe for maximum heat exchange and enter the tank
through an
unvalved upper hole.
To preferentially cool the tank to feed, for example, a chiller or drink
fountain, the setup is
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reversed with valves located outside the conduit, water inlet above, and
conduit and tank
outlets located low.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cross section end view (at 1-1, Fig 2) of the vertical
embodiment showing the
concentric arrangement of the drainpipe, sleeve, housing, tank, compressed 0-
ring
gasket, tank water outlet, and one embodiment of a valve body with flap
valves;
Figure 2 is a side view of the same embodiment showing the lower water inlet
in the
housing below the tank, and the upper outlet from the tank. Only two
convection
holes are shown. Flap valves are not shown so as to more clearly show the
other
components;
Figure 2a shows the same embodiment with domed end caps to resist bursting. A
grommet
seals the end caps to the housing. Optional tie rods are shown to reinforce
the end
caps. Extensions to the tie rods can serve as support legs;
Figure 2b shows how multiple tie rods can be added internally to allow simpler
flat end
caps;
Figure 3 is a section end view (at 3-3, Fig 4) of the horizontal embodiment. A
single flap
valve assembly is positioned as low as possible to be in the coldest strata.
The bottom
edges of the upper outlet holes are flush (or higher) with the top of copper
drainpipe
to prevent cold water overflow from a cold conduit resulting from a cold
drainpipe
carrying cold drainwater;
Figure 4 is a side view of the same embodiment showing the water inlet on the
right end
of the housing and the horizontal water flow from right to left and up along
the
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drainpipe sleeve through which drainwater counterflows left to right;
Figure 4a shows an internal tie rod on centre for maximum end cap strength.
Reinforcing
rings bonded/secured to the housing are also detailed;
Figure 5 is an exploded perspective of a horizontal housing with its
convection holes, and
with valve assembly below. At the lower left of the figure is shown a U-shaped
line
representing a seal for use against housing end to prevent cold water leakage
from
conduit;
Figure 5a details how the gasket and optional compensator are positioned for
insertion of
the copper drainpipe and sleeve. The housing can be squeezed to an oval to
provide
added slide-in clearance between them for the drainpipe;
Figure 6 shows a segmented and concave flap valve of thin plastic such as
polyethylene
with the dotted holes representing the holes in the housing against which each
valve
segment seals;
Figure 7 shows a side view from the compensator side. Upper outlets in the
housing are
not valved. Multiple lower inlets are shown for inlet flow distribution. Valve
channel
rubber clamp bands are also shown;
Figure 8 is the same embodiment from the gasket side with single lower inlet;
Figure 9 shows an end view of the heat exchanger's housing squeezed narrower
and taller
(oval) for assembly clearance. A removable alignment strip is shown between
parallel
gasket runs on each side of slit. Also show is full length gasket alignment
bar which
can be permanently bonded to inside of housing;
Figure 9a shows the same embodiment un-squeezed that results in
gasket/compensator
compression. Compensator end loops are shown pinned to prevent movement during
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assembly after which they can be cut flush;
Figure 10 is a perspective of the end of alignment tool for slip and gasket
being a notched
strip and a tapered expansion plug with slots to slide onto the strip;
Figure 11 shows an enlarged side view of the sleeve and gasket in operational
relationship. Vents (grooves) on left side are longitudinal and
circumferential on right;
Figure 11a shows a three piece gasket alignment jig. Two bent wire rods slide
into the
ends of a tube and engage the ends of the slit in the sleeve to hold gasket
runs in
position away from the slit until compressed during assembly;
Figure 12 shows in a close-up of a portion of Fig 11 how the circumferential
vents
terminate through the slit's flanges to leave them open to the gap and
therefore to the
ambient for leak detection;
Figure 13 shows in perspective how the one-piece gasket has looped ends and
straight
runs that co-contact the margins and paths on the housing inner surface and
the
drainpipe (or copper sleeve) to form a sealed conduit with inlet and outlet;
Figure 14 shows ways in which holes at the bend line of the flange intersect
the vents, and
how the gasket contact path is clear of such features (only one flange is
shown);
Figure 15 is the same as Fig 14 with the flange now bent showing how any
leakage picked
up by the vents can flow into and along the slit between the flanges and then
out
either end of the housing to the ambient where the leak is revealed as a drip;
Figure 16 shows a cross-section of a manifold in two configurations. The upper
configuration is machined and bonded to the end cap of the tank (or all made
in one
piece) and doubles as a reinforcement against burst pressure. It has a single
groove
for an 0-ring to seal with the housing and lies adjacent the flow distribution
groove.
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The lower configuration shows 0-rings seals on each side of the flow
distribution
groove. Both configurations incorporate an inlet fitting. Also shown are
blocking
means to prevent water pressure from pushing the gasket's end loop out;
Figure 17 is a schematic view showing how the water density (warmer, lighter,
upper, and,
colder, heavier, lower) causes horizontal layers or strata to form at
different elevations
in the tank and conduit. This effect is due to the convection driven flap
valves that
prevent a colder, heavier column of water in the conduit from flowing out and
cooling
the tank;
Figure 18 shows the same temperature/density strata feature but horizontally
oriented.
Here all unwanted cooling occurs only below the top of the drainpipe/sleeve
which,
when cold drainwater is flowing, becomes submerged in the coldest layers
leaving the
stored heat above largely unaffected;
Figure 19 shows the heat exchanger with a waste stream inlet fitting that
accepts different
streams of waste fluid such as drainwater, warm rain, gaseous waster from
clothes
dryer exhaust, water heater exhaust, or other sources. Also shown is a back
flow
preventer or check flap valve to control odour. Also shown is a vent to the
outdoors
for final gaseous exhaust;
Figure 19a shows another typical back flow preventer where a pre-moulded cuff
of rubber
has its outlet end curled and closed when there is no flow and so prevents
back flow
but uncurls into a straight tube by blown gaseous waste or exhausts;
Figure 20 is a side view showing how the tank can be built from components
that are
welded/bonded to the housing to resist bursting from water pressure;
Figure 21 shows an alternative and simpler flap valve arrangement without a
valve
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channel where one flap is clamped in place between the housing (not shown) and
gasket, and a second flap between housing and compensator;
Figure 21a is another arrangement where two spaced apart compensators each
clamp a
flap valve beneath;
Figure 22 is an cross section end view through convection holes in the housing
showing
how the flap valve 'hinges' are clamped by the compensator leaving their outer
wings
free to move with convection currents. The left flap valve is shown open to
allow
inbound convection while the right side flap valve is shown closed as would
happen
when cold waste fluid flows; Also shown is how the housing can be extruded
with an
alignment protrusion to space the gasket's straight runs;
Figure 22a shows how the vertical embodiment can use the compensators to hold
flap
valves that serve multiple housing convection holes;
Figure 23 shows a plan view of a flap valve having wide separations between
the flaps to
allow individual flap movement in response to varying density along the height
and
also provide convection currents with a shorter flow path;
Figure 24 shows a side view of the device showing how pumped drainwater from
wash
machines can also be inputted. A vertical format is shown that occupies less
floor
space which could be advantageous in some settings;
Figure 25 shows a topside view of a vertical embodiment with multiple heat
exchangers in
a single tank;
Figure 26 is the same embodiment in phantom view;
Figure 26a is a side phantom view of a tandem or series arrangement of two of
the units
shown in Figure 26;
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Figure 27 shows an end view of a horizontal embodiment with multiple heat
exchangers
in a single tank;
Figure 28 shows a phantom side view of the same embodiment.
DETAILED DESCRIPTION OF THE INVENTION
The following description should not be used to limit the scope of the present
invention.
Other examples, features, aspects, embodiments, and advantages of the
invention will
become apparent to those skilled in the art from the following description. It
should therefore
be understood that the inventor contemplates a variety of embodiments that are
not explicitly
disclosed herein. Its use in a hygienic hot water system will be derailed
herein.
Hygienic hot water flows can be of two types:
1. continuous flow as in showering when hot water and drainwater flow
simultaneously or
2. batch flow as in a wash machine where an appliance 400 fills and cleans for
a time with no draining, and then drains for a time with no cold water flow.
Drainpipe heat exchangers for continuous flow have long been commercially
available.
The instant invention is the only known heat exchanger that recovers and
stores recovered
heat from both continuous and batch flows, regardless of the varying
temperature, volume
and times-of-flow of the waste fluid. It preferentially only heats the cold
water supply for a
water heater or faucet. It operates automatically, needs no power. Its high
performance
ensures widespread societal benefits.
Apparatus 100 on ground G has pressure tank 4 with a drainpipe heat exchanger
200
extending through it. It is plumbed into a drainage system and into a supply
of fresh water C.
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Tank 4 supplies pre-tempered water from outlet 8 to a tempering appliance 400
on ground G.
Exchanger 200 pre-tempers or pre-heats water C for appliance 400 by forced
convection
when in continuous flow mode, and by natural convection when in batch flow
mode.
If its waste heat that is being recovered and stored in the tank 4 it follows
that cold
drainwater must not be allowed to cool it. This inventive feature is achieved
as follows.
Heat exchanger 200 has a thermally conductive drainpipe 1 (i.e., copper) whose
central
portion is enclosed in a larger cylindrical plastic housing 3 sealed to each
end of tank 4 and
has annular space 50. Housing has openings 3a, 3c into tank 4. One end of
housing 3
extends beyond tank 4 to include water inlet 9. Drainpipe ends la extend
beyond each end of
housing 3 for plumbing connection.
Sleeve 2 has slit 2a open to the ambient for leak detection. Sleeve 2 is
thermally
conductive and surrounds central portion of drainpipe 1 providing double wall
protection
from cross-contamination. Sleeve 2 also has vent grooves 20 whose ends open to
the ambient
also for visual leak detection.
One-piece compressible gasket 5 circumscribes annular space 50 including inlet
9 thereby
creating conduit 50 for water to flow through adjacent sleeve 2 and into tank
4.
Conduit 50 has outlet 3c inside tank 4. Tank is therefore filled via inlet 9.
Pre-tempered
water Cc exits tank 4 through outlet 8 into appliance 400. Pre-tempered water
Cc can also
feed piping, fixtures and faucets in a building.
Holes 3a in housing 3 allows water Ce in conduit 50 to naturally convect with
water Cc in
tank 4. The direction of convection through holes 3a is determined by the
relative
temperatures of water Ce and Cc. Holes 3a have associated floating (buoyant,
frictionless)
flap valve(s) 7 that move with convection currents Ca, Cb, Cd to cover or
uncover holes 3a.
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If the drainwater A is cold then the small volume of cooled water Ce inside
conduit 50 would
convect outward (cold water is heavier). However such cold convection currents
Ca push
valves 7 to close holes 3a (top portion of Fig 1) so that cooled water is
locked in conduit 50
thereby preventing the unwanted cooling of water Cc in tank 4.
(Fig 1 shows valves 7 at top and bottom portions of the Fig as working
oppositely. This is
just for description purposes. In operation valves 7 are pushed open or
closed.)
With a warmer drainwater A the opposite convection flow occurs. Colder and
heavier tank
water Cc push valves 7 open to enter conduit 50 where it is heated to be
lighter and is
therefore displaced upwards into tank 4 , by surrounding colder water, where
it is temporarily
storage until demanded by someones use of tempered water from appliance 400.
For continuous hot water use, forced convection occurs whereby the valves 7
are force-
closed by pressure in conduit 50 ensuring the continuous incoming cold water
has to flow the
full length of conduit 50 for maximum heat exchange with concurrently flowing
warmer
drainwater A which continuously heats drainpipe 1 and sleeve 2. Pre-tempered
water Ce
whereafter it exits Cd into tank at upper outlet 3c (Fig 2). This forces tank
water Cc out of its
outlet 8 when pressure is released by tempered (hot) water is drawn from
appliance 400.
For batch hot water use, such as filling a wash machine, there is no
concurrent freshwater/
drainwater flow so no heat is exchanged in exchanger 200 and it is previously
heated water
Cc stored in the tank that feeds the appliance.
When only hot drainwater is flowing, free convection again occurs where the
colder,
denser water in the tank push the valves open to travel upwards in conduit 50,
be heated by
the warmer sleeve 2, and exit as pre-tempered water Cc into the tank 4.
When only cold drainwater is flowing, the small volume of water in the conduit
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immediately becomes colder and heavier and pushes the flap valves closed
preventing it from
leaving and cooling the tank water. This preserves the stored thermal energy.
For heat rejection (pre-cooling for a chiller) the flap valves are on the
outside of the
housing and the tank outlet at the bottom so as to operate in reverse with the
tank being
advantageously cooled by colder, heavier drainwater. Such a scenario would
benefit food
operations where refrigerated water is essential to cool and rinse food
stuffs, and for ice
makers, drink fountains and the like.
Also by way of background, the thermal performance of a fluid-fluid heat
exchanger is its
rate of heat transfer Q = (AT * A * T)/R where,
temperature differential (AT),
thermal resistance (R) through the wall separating the fluids,
wetted area (A) and
time (T).
turbulence at the wall also has an effect, more being better. Turbulence adds
to (Q) by
dislodging the boundary laminar layers of fluid that naturally form adjacent
any surface
(sleeve 2) and which add (R).
Heat transfer (Q) between contacting surfaces of drainpipe 1 and sleeve 2 is
further
governed by contact pressure which in the instant invention is applied by the
supply water
pressure in tank 4 and conduit 50 which continuously constricts sleeve 2
around drainpipe 1
which is allowed by slit 2a which is thereby narrowed.
The device has vertical and horizontal embodiments. The flow characteristics
in the heat
exchanger are different in each.
For the vertical, drainwater flows by what is referred to as 'a falling film'
where the entire
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inner surface (A) of the drainpipe naturally becomes circumferentially wetted
with a thin,
slow falling film of the descending drainwater and the entire surface
transfers heat somewhat
evenly. Gaseous flow has no such flow characteristic and is generally chaotic
but also evenly
distributed. The length of the vertical embodiment is generally limited by
floor to ceiling
dimension. Multiple units in parallel can be installed for more heat recovery.
For the horizontal, drainwater flows trough-like in the lower portion of the
drainpipe
which is the only portion wetted and and where most heat is transferred. Heat
conduction
through the wall of the drainpipe therefore provides less heat transfer.
Gaseous flows can
contact the entire tube wall in places. To its advantage, length is only
limited by floor size
and parallel units can be installed to provide virtually unlimited area (A).
In both embodiments multiple units can be joined in series and/or in parallel
to achieve
greater savings.
There are two major components to the instant device: the tank and the heat
exchanger.
and are described separately.
First the tank.
In all figures tank 4 is a 'pressure retention vessel' of plastic, metal or
fibreglass or in
combination, such as a plastic liner in a steel sleeve. A water outlet 8
connects to an end use
(appliance, faucet, radiator). The tank can be left uncovered in heating
season to act as an air
heater reducing energy use.
Each end 12,12a of tank 4 is capped and the caps each have at least one large
hole 92a for
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housing 3 to seal through. In the vertical design the holes 92a are on centre
while in the
horizontal the holes 92a are best offset towards the bottom where the colder
tank water Cc
will always collect and therefore yield the fastest heat transfer due to the
AT.
Several methods can be used to make the tank 4 both burst proof and low cost.
One is a
water pressure regulator 9b at inlet 9.
Another is to bond the end caps 12,12a to the tube and to bond reinforcement
plates 14 to
the end caps. Plates 14 have 0-ring(s) 13 within to seal against outer housing
3 of the heat
exchanger 100,101.
A second method is the use of a one-piece domed-end cylinder shown in Fig 20
with a
sealing grommet 92 (Figs 2a, 2b) fitted in the hole 92a.
A third method uses well known tie rods 90 and tie plates 91 as shown in Fig
2a. The rods
90 can be internal as in Fig 2b and extend through the end caps 12,12a with
suitable external
leakproof fasteners such as rubber-faced washer or rubber sleeves running full
length and to
the outside where they are flared and compressed by washers and nuts. Tie rods
90 can
include extension legs 90a to support the vertical device (Fig 2a, 2b).
A fourth method is shown in Fig 20 where the tubular housing 3 of the heat
exchanger
does double duty as a tie rod by plastic welding and/or adhesive bonding the
end caps 12,12a
to the housing (and to tank 4) at positions indicated by joint 220. This
transfers bulging/
bursting forces on the caps to a tensile load on the housing which can easily
resist it.
A fifth method is shown in Fig 4a where band or ring retainers 93 are bonded
to housing 3
outside of the end caps at each end to transfer tensile loads to housing 3 as
in a tie rod.
Retainers 93 may also be metal clamps or `push-on' toothed fasteners for
smaller diameters.
Manifolds 70,80 may also be bonded/welded to housing 3 at the inlet end for
the same
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purpose.
A sixth method is to solder bosses 94 (Fig 2b) to the drainpipe end stubs to
receive the
water pressure force from retainers 93 turning the drainpipe into a huge tie
rod. Rolling
protrusion bosses 94 (Fig 2) in the wall of each drainpipe stubs la can
accomplish the same
restraining boss function without the complexity of soldering separate
components together.
Outlet 8 in the tank wall is positioned near the top for pre-temper heating
and neat the
bottom for pre-temper cooling.
Second, the heat exchanger
Heat exchanger 100 in Figs 3,4, 4a is for horizontal installation and 101 Figs
1, 2, 2a, 2b
is for vertical. Each has multiple elements: drainpipe, sleeve, housing,
gasket, compensator,
valving, and manifolds.
Drainpipe
Drainpipe 1 is straight and round and can be of any diameter, usually the same
as available
drainage drainpipe (1, 11/2, 2, 3, 4, 6") and it is longer than the tank so
that its ends are
exposed as stubs la which are of sufficient length for standard plumbing
connections.
Sleeve
Optional sleeve 2 is a pinch-rolled sheet copper cylinder with a thickness
such as 0.020 to
0.060 inch (0.5-1.5 mm) and fits tightly around drainpipe 1. Sleeve 2 is
shorter than drainpipe
1 and has a full length slit 2a. Sleeve 2 may have flanges 2b along one or
both edges of slit
2a, to separate the straight runs 5d of gasket 5 from crossing over slit 2
which would cause a
leak. In Figs 10, 11, 12 14, 15 sleeve 2 is shown with vents 20. Vents 20 have
a rounded
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profile for gasket conformity. Vents 20 are straight, extend full length and
are open at each
end. Circumferential vents 22 begin and end at slit 2a. The two may be
combined into a
cross-hatch pattern.
Flanges 2b and vents 20,21 should have intersecting vias 22, 22b, 22c (Figs
12, 14,15) to
ensure that vents are not crushed or otherwise blocked in forming the flanges.
Different
configurations of vias are shown in Fig 14,15 including a hole 22b, slot 22
and vee notch 22c.
Figs 14 and 15 show paths 5h onto which straight gasket will be compressed.
Separate
alignment rod 3k or protrusion 3j (Fig 22) integrally extruded with housing 3
serve this same
purpose as bent up flanges.
Another method of providing vents is to emboss grooves 30 (one shown) into the
wall of
drainpipe 1 between end stubs la. The grooves 30 could be formed along the
entire drainpipe
1 after which the end stub regions la could be reformed to the round. Yet
another method is
to form flats 31 (one shown) along the outer wall of drainpipe 1 between stubs
la. Such flats
are easily filed, scraped or milled along the tube wall. The grooves 30 and
flats 31 can extend
over stubs la if a seal between stubs la and the plumbing connection (P in Fig
16) can be
guaranteed such as by the use of a rubber coupling and/or a sealant between.
Insulating
sleeve 3p shown in Fig 2 reduces a possible small heat loss by 'lateral'
convection through
exit 3c when drainpipe 1 is colder that tank water Cc.
Housing
Housing 3 is a plastic tube shorter than drainpipe 1 but larger in diameter so
as to create an
annular conduit 50. One end of housing 3 extents far enough to accommodate
water inlet 9
and reinforcement plate 9a or manifold 70, 80.
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Along the housing's length are holes 3a and associated flap valve 7 to control
convection
therethrough. One or more unvalved outlet holes 3c are have the highest
possible placement.
Horizontal housing 3 has outlets 3b. Housing 3 can also have purposeful holes
3d (Fig 7) to
secure any compensator 5a, although the inlet 9 and outlet 3c can be used. Fig
8 shows the
side view from gasket side and where a single inlet 9 is used on the
compensator side where
there is no obstruction to flow of fresh water C into conduit 50.
A channel-shaped flap valve duct 6 bridges across the rows of holes 3a. It has
holes 6a in
its side wall(s). Rubber bands 11 can be used to secure duct 6 to housing 3
and to clamp flap
valve 7 in between.
Housing 3 can have its rims chamfered 3' (Fig 16) for ease of assembly of
gasket loop[s
5e. The rims of housing 3 can have gasket positioning marks 3h diametrically
opposite
compensator 5a. A separator bar 3k (Fig 9) of plastic or metal can be bonded
inside housing 3
to separate the gasket straight runs 5d at mark 3k to prevent gasket movement
and serve as a
limiter to prevent over compression of gasket 5.
Gasket
Gasket 5 can be an elongated 0-ring of a water-safe elastomer such as Nitrile
or EPDM. It
gets shaped on assembly as shown in Fig 13. Gasket 5 encircles both ends of
the drainpipe
with loops 5e that are connected by parallel straight runs 5d. Its linear
length is
approximately equal to two drainpipe circumferences and two drainpipe lengths.
Two or
more gaskets 5 could be used for redundancy. Gasket 5 is compressed on
assembly.
Gasket 5 can be used to clamp flap valve 7 as shown in Figs 21, 21a, 22.111
Fig 5a the
gasket 5 and compensator 5a are shown in position for the insertion of
drainpipe 1. Gasket 5
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is placed in housing 3 and pulled back (stretched slightly) on the outside and
held there with
hooked-end wire H. In this way parallel runs 5e are held taunt and aligned
with index mark
3h (Fig 9) at each end.
Compensator
Compensator 5a can be made from the same 0-ring material as gasket 5 or be a
solid
having a height equal to the calculated compressed thickness of gasket 5. It
is pulled into a
linear form such that the ends can be passed through holes 3d (or inlet-outlet
holes 8,9) and
held there by pins 5b. It does not extend full length so inlet water C is able
flow to either side
of conduit 50. On assembly the compensator becomes compressed so the pins can
be
removed and ends snipped off if necessary. Fig 13 shows two separate
compensators that
along with the gasket 5 provide three-point self-centring of the drainpipe 1
in the housing 3.
Fig 21a shows how the compensator can clamp flap valve 7 in place. Fig 22
shows the flap
valve 7 open on the left side and closed on the right. Of course that cold not
happen at the
same density strata and is for illustrative purposes only. Also shown in Fig
22 is how the
segmented flap valve 7 with slots 7c can be used to reach distant holes 3a (on
right). The
slots 7c will allow inflow water Ca (Fig 1) to reach conduit 50 and all areas
of sleeve 2
quickly because currents can flow through the flap valve slots 7c. Wide slots
are preferable
for that reason. Alignment protrusion 3j can be extruded or bonded in to
simplify assembly.
Manifold
The longer end of the housing 3 of heat exchanger 100,101 has the fresh water
(or other
liquid) inlet. It can be a single fitting 9 and can have an associated
reinforcing pad 9a (Fig 2).
In Fig 16 two designs of a manifold are shown in cross section: manifold 70
above and
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manifold 80 below. Each manifold design includes a fresh water inlet 9 which
intersects an
internal circumferential water distribution groove 73.
In Fig 16 grooves 72 are for 0-rings to seal to the groove 73 housing 3.
Groove 73
distribute water from fitting 9 all around the housing 3 to multiple inlets
3f, 3g which open
into heat transfer conduit 50. Lower manifold 80 has dual 0-rings 13 designed
to allow it to
be slid on from the end of housing 3. Manifold 70 has a single 0-ring 13 and
is intended to
be one-piece with end cap 12a and so dispenses with reinforcing plate 14.
Lower manifold 80
is shown to have an outer flange 71 as one method to retain 0-ring 5 against
internal water
pressure, and also shows another method of a flared end 2f (or tabs, not
shown) on rim of
sleeve 2. A third method shown is to bond a retaining ring 2j into housing
adjacent gasket
loop 5e. Yet another method is to use the plumbing connection adaptor P.
commonly a thick
rubber coupling with steel gear band clamps (only top half shown) that
tightens around stub
2a, to butt against end of housing 3 or trap a spacer ring 2k against the
gasket loop 5e.
Inlets 3f and 3g are shown enlarged in Fig 16 to be different with inlets 3g
(top, Fig 16)
being perpendicular while the 3g inlets (below) are angled outwards to direct
water C against
gasket 5 to prevent possible erosion of the copper from hard water jetted
directly against it.
For the same reason, inlets 3g are positioned such that water C is deflected
away from the
copper sleeve 2 or drainpipe 1.
Fig 16 also shows turbulator 35 such as a screen or mesh inserted in conduit
50 to enhance
heat transfer by creating turbulent conduit flow Ce.
Valve
Flap valves 7 shown in Figs 5,6, and 21-23 are made from strips of thin
flexible material
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with water-like density such as polyethylene or polypropylene, suitable for
permanent
immersion in water and with a density similar to that of water so as to move
as freely as
possible. This is more important in the horizontal embodiment where a heavy
flap valve 7
would sink against the holes 3a and require too much free convection current
force to open.
One edge of the strip is free to float in the water and so is friction-free
and readily moved by
convection currents inflow Ca and outflow currents Cb (Figs 1,3).
A preferred flap valve embodiment, particularly for the vertical device, is
shown in Fig 6
and 23 is a segmented flap valve 77 with spaces 7c that define individual
valves for each
inflow 3a (represented in dotted outline). Segmented valves 77 are able to
open and close
holes 3a independently and automatically to optimize convective flow at each
density strata.
This is more important for the vertical exchanger 101 where strata develop
over a
considerable vertical height and so the range of densities will be more that
in the horizontal.
The segmented flap valve allows for tailored openings-and-closings inside and
outside of
housing 3 all along its height based on relative densities to maximize
performance.
Fig 23 shows how one line of larger holes can have a flap valve 77 held in
place with a
strap 7e that locks in holes 7f in housing 2, and/or is inserted through holes
7m in flap valve 7
or 77 and then through housing 3. If strap 7e is plastic it can be melt-rivet-
ended on the
outside of housing 3 in a countersunk hole (not shown) and then levelled so
that a smooth
exterior is maintained for safe entry through end seals 13. Fig 23 also shows
slots 7c widened
to the maximum to provide unhindered access for inflow water Ca from below
flap valve 7
into conduit 50.
Valve attachment
Page 19 of 27
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Figs 1,2 and 3,4 show how channel shaped flap valve ducts 6 have side holes 6a
for
valves 7. Ducts 6 are clamped to the sides of housing 3 with elastomeric bands
11 trapping a
margin of the flap valve 7 between. This leaves the remainder of the flap
valve 7 free floating
and easily moved by convection. Fig 1 shows two flap valve ducts 6 along each
side of
vertical housing 3 and bridging holes 3a, while Fig 3 shows a single flap
valve duct 6
horizontally along the bottom also bridging holes 3a. Valves 7 attached by
ducts 6 can have a
longitudinal hem portion 7a to locate on the clamping edge of duct 6 for added
security
during assembly.
Ducts 6 contact and preferably are sealed 7d (Fig 5) to end caps 12,12a to
prevent leakage
from conduit 50 when conduit water Cc is cold.
In another embodiment flap valve(s) 7 or 77 can be internal. They can be
attached inside
the housing as shown in Figs 21-22 such as by trapping them under the
compensator(s).
Valve 7 or 77 may also be trapped under gasket 5 as shown in Fig 21 if thin
enough so as to
not prevent the gasket from making an effective seal where it runs off the
ridge of the flap
valve material at each end. Fig 22a shows in the vertical device how two
compensators 5a
can be spread apart and used to spread apart the flap valves 7 or 77 to reach
further around
the wall of housing 3 to inflow holes 3a. Of course if spread too far apart
they will prevent
squeezing the housing for assembly as detailed later.
In another embodiment flap valve 7b in the upper part of channel 6 in the
lower part of Fig
is a free floating strip that is made of a slightly stiffer material to
maintain flatness/
straightness and ensure a good seal against holes 6a when closed by convection
currents. The
strip, duct dimensions and shape are cooperatively arranged to provide just-
sufficient
movement without the possibility of the flap valve jamming open or closed. In
the vertical
Page 20 of 27
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embodiment, because it will sink or float thereby contacting an end cap, it
can be designed to
'hinge' or pivot from its contacting end instead of from along its length.
Assembly- Heat exchanger
Where the sleeve 2 has no flanges the gasket is placed through housing 3 with
gasket runs
5d on each side of rim index marks 3h (Fig 9) and/or on each and of spacer rod
3k shown in
Figs 8,9. The outside portions that will become end loops 5e are hooked
together with wire
H (Fig 5a) tensioning the runs 5d straight and preventing their accidental
movement. The
compensator 5a is locked in place with pins 5b (Fig 7), or by friction in
tight holes, tape,
bands, or other means.
In a long vise or with clamps, the housing is squeezed (Fig 9) into a slight
oval/ellipse to
increase the vertical space between the gasket and compensator which will
allow the smaller
drainpipe 1 (with or without sleeve 2) to slide freely through the housing and
not dislodge the
gasket 5 or compensator 5a. After aligning the slit 2a between gasket runs 5d
and index
marks 3h, the vise is opened whereby the housing's considerable spring-back
force returns it
to round compressing the gasket and compensator against the drainpipe 1
locking them in
place.
The gasket runs 5d are verified to be on each side of gap 2a in sleeve 2 and
centred on
index marks 3h on each rim. A spacer rod 3k shown in Fig 8,9 can be inserted
between
gasket runs 5d to add spacing if required. It can be removed or left in place
as a spacer to
prevent over compression and movement of gasket runs 5d. When pressurized with
water, the
long sides of the ellipse will tend to round out resulting in further gasket
compression to the
design goal of about 20% of its initial size (varying with gasket composition
and size).
Page 21 of 27
Date Recue/Date Received 2021-03-08
Additional compression force can be supplied by clamp structures 3m as shown
in dotted
outline in Fig 9a.
Hook H can be removed allowing the dangling loops 5e to be stretched around
the stub
ends 1 a of the sleeve/drainpipe assembly. Press dies at each end allow a
clamp /press to force
the loops 5e into their compressed positions in housing. Lubricant such as
soap or K-Y jelly
will ease their sliding-compression. The ends of the housing 3 can have a
chamfer 3' (Fig 16)
to further assist insertion.
Another method for un-flanged sleeves is to have the four corners of slit 2a
nipped off as
in Fig 11 to create a locater notches 2c that a straight, stiff wire rod 2d
with a bent end can
engage. As shown in Fig 11 a two such flanged rods 2d slide snuggly into a
plastic tube 2e
almost as long as the sleeve 2. The tube 2e will nestle in the slit 2a as
wires 2d lock into
notches 2c. The gasket 5 will then lie on either side of tube 2e eliminating
the possibility of
crossing over the slit which would create a leak. The tube can remain in place
for added
security against gasket movement or be removed after the the gasket has been
compressed. If
used, tapered plug 2h would require clearance notches for the bent end of the
wire rod 2d
(not shown).
Another assembly method to ensure gasket 5 doesn't move during assembly when
there
are no flanges on sleeve 2 is to make one vent 20a directly opposite slit 2a.
Aligning marks
3h on rims of housing 3 (Fig 9) can serve to correctly position the ends of
gasket. runs 5d.
The raised ridge of vent 20a is slid into the grooved space in the compensator
5a (Fig 9). An
alignment strip 2f is inserted with one longitudinal edge sliding in vent 20a
and its opposite
edge sliding through slit 2a and between straight parallel runs 5d of gasket
5. Alignment strip
2f can have end notches 2g to fit with slots 2i in plug 2h to hold the sleeve
2 tight against
Page 22 of 27
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straight runs 5d of gasket 5 while its end loops 5e are arranged to encircle
the sleeve.
If the sleeve 2 has flanges 2b, the flanged sleeve 2 can be installed first in
housing 3
between gasket 5 and compensator 5a. The sleeve 2 is constricted sufficiently
(concentrically
spiralled) to enable its entry between the gasket and compensator allowing one
flange to slide
into a space between the parallel straight runs of the gasket. If there are
two flanges the
second flange is urged into that same space using tapered plugs 2h (Fig 10)
from each end to
expand the curled sleeve 2 back to its original round shape. With this method
the drainpipe 1
is inserted last where, by design, it expands the sleeve slightly to finally
compress gasket 5
and compensator 5a. The compressed gasket 5 then becomes an effective seal.
Assembly - Tank
If the tank is one-piece with the end seals, 0-rings or grommets, in place,
and the heat
exchanger has internal convective valving, then it is simply inserted through
one end and out
the other. The housing and/or seals can be lubricated to ease entry.
If the tank is to be assembled from tube and end caps, then assembly can
follow different
paths depending on the flap valve embodiment. With external duct valves and
fixed inlet 9,
one end cap 12a with plate 14 can be slid over the non-inlet end of the heat
exchanger down
onto the inlet end. Next the flap valve duct 6 with flap valves 7,7b, 77 is
positioned and
secured to housing 3 with bands 11. Next the main tank tube is joined (bonded,
welded) to
end cap 12a. The second end cap can then be slid over the housing 3 and joined
to the tank 1
to complete the assembly.
If the design of the device includes a slide on manifold, then assembly can be
as with the
Page 23 of 27
Date Recue/Date Received 2021-03-08
one-piece with the manifold being added last.
Reinforcing bands 93 are added when and as required by sliding them over
housing 2
with adhesive or welded in place..
Figs 17 and 18 depict the stratification principle in any fluid. The darker
areas represent
colder, heavier water. In Fig 17 the housing 3 is filled with cold water Ce
from a cold
drainpipe 1 and is shown remaining in place because the flap valves have
closed holes 6a (not
shown) preventing the tall heavy column from pouring out into the tank and
cooling it. In Fig
18 the same holds true except for the space above the drainpipe i where the
holes 3b (not
shown) are at level L just above the drainpipe upper surface. Below that level
L cold conduit
water Ce stays in place, If outlet holes are too low, it will spill out into
the tank.
Figs 19,19a and 20 show how different waste streams or flows of liquid A and
gaseous B
can be fed from different sources into a manifold 200 shown with three inlets
to the drainpipe
1. In Fig 19a for gaseous flows B a check flap valve or back flow preventer
flap valve 150
can be used. The gaseous waste from a clothes dryer, a gas water heater or
ventilator being
fan blown, pushes open flap valve 80 depicted as a lightweight flap. In Fig
19a the check flap
valve 150 is a curled rubber cuff 81 whose mouth 82 automatically curls shut
when there is
no gas flow and uncurls from fan generated pressure to allow gas flow into the
drainpipe. A
vent 160 to the outdoors can be used to vent excess gas B' from building up in
the sewer
drainpipe.
Fig 20 shows how the tank 4 can be assembled from components weld/bonded at
locations
220. Flat end cap 12a bonded at 210 with grommet 92 sealing to hole 92a and
housing 3 and
reinforcing ring 93 bonded to housing 3 to contain internal pressure. under
water pressure the
Page 24 of 27
Date Recue/Date Received 2021-03-08
grommet is compressed into a tight seal against the housing 3 and the
reinforcing ring 93
and/or boss 94.
Fig 24 shows how the device can be fed pumped waste liquid A' such as from a
washing
machine or dishwasher or in a laundromat, where a smaller diameter drain
drainpipe 300
connects to manifold 200 along with regular waste streams A, and/or B. Also
shown is funnel
inlet 250 that encourages liquid flows to spread circumferentially into a
falling film as it
enters drainpipe 1 thereby making use of its full length for heat transfer.
Figs 25 to 28 depict the use of more than one heat exchanger 100,101 in a
common tank 4
where they may have separate or shared waste flows such as one for liquid and
one for
gaseous waste to maximize heat recovery and where they can be sized for
optimum
performance.
For chiller applications such as in food preparation, ice making, drinking
fountains, where
chilled water is required, a waste stream of indeterminate temperature is used
to
preferentially cool the warmer incoming fresh water. This results in the
faster chilling to a
final temperature with less new energy use, and a more abundant supply of cold
water. In
such applications the setup is reversed with the flap valves 7 being outside
of conduit 50 to
prevent already colder tank water from entering a warmer conduit.
Page 25 of 27
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