Note: Descriptions are shown in the official language in which they were submitted.
1
HEAT EXCHANGE
TECHNICAL FIELD
[0001] This disclosure relates to heat exchange. More specifically, this
disclosure relates to heat
exchange in which temperature differentials drive fluid flow.
TECHNICAL BACKGROUND
[0002] Fluid heat exchange systems are found in many applications, whether for
cooling or heating
residential, commercial or industrial setting, in vehicles, in conjunction
with machinery, or
otherwise. Fluid heat exchange systems operate by heating a heat exchange
fluid, such as water or
glycol, or water and glycol, or steam, in a heat exchanger, circulating the
fluid through a circuit to
a heat sink where the fluid is cooled, and recirculating the fluid to the heat
exchanger where it is
heated again. Non-limiting examples of heat sinks include vehicle radiators,
heating radiators, and
evaporators of heat pumps.
[0003] In many applications, a mechanical pump circulates heat exchange fluid
through a heat
exchange system. A mechanical pump may be driven by electrical power. If the
electricity source
fails, the loss of power to the pump may render the heat exchange system
inoperative even though
the heat source may continue to function. For example, if the heat source is
an oil or solid fuel
burner, the heat source may continue to function in the absence of
electricity. Further, electrical
pumps may require inspection and maintenance and may impose operating costs
for electricity.
[0004] In other applications, sometimes called "gravity heating systems",
heating the heat
exchange fluid in a heat exchanger disposed near the lowest point of a heat
exchange system causes
the heated heat exchange fluid to rise through the system toward heat sinks in
the heating circuit.
As the heated fluid dissipates heat through the heat sinks, the fluid cools,
causing the cooled heat
exchange fluid to descend toward the heat exchanger. While such systems are
known to operate
without the need for a mechanical pump to drive flow, they may be susceptible
to the formation
of vapour, such as steam, that can create unwanted noise and premature damage
to system
components. Further, such systems may be difficult to design and install, with
numerous
constraints on the position and sizing of system components. Despite existing
approaches, barriers
remain to circulating flow without the need for a mechanical pump.
Date Recue/Date Received 2021-03-19
2
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] In drawings which illustrate by way of example only embodiments of the
present
disclosure:
[0006] FIG. 1 is an illustration of an example embodiment of a fluid heat
exchange system;
[0007] FIG 2 is an illustration of a check valve for use with the embodiment
of FIG. 1; and
[0008] FIG 3 is an illustration of another check valve for use with the
embodiment of FIG. 1.
DETAILED DESCRIPTION
[0009] Fluid heat exchange systems are found in many applications, whether for
cooling or heating
residential, commercial or industrial setting, in vehicles, in conjunction
with machinery, or
otherwise. Fluid heat exchange systems operate by heating a heat exchange
fluid, such as water or
glycol, or water and glycol, or steam, in a heat exchanger, circulating the
fluid through a circuit to
a heat sink where the fluid is cooled, and recirculating the fluid to the heat
exchanger where it is
heated again. Non-limiting examples of heat sinks include vehicle radiators,
heating radiators, and
evaporators of heat pumps.
[0010] In many applications, a mechanical pump circulates heat exchange fluid
through a heat
exchange system. A mechanical pump may be driven by electrical power. If the
electricity source
fails, the loss of power to the pump may render the heat exchange system
inoperative even though
the heat source may continue to function. For example, if the heat source is
an oil or solid fuel
burner, the heat source may continue to function in the absence of
electricity. Further, electrical
pumps may require inspection and maintenance and may impose operating costs
for electricity.
[0011] In other applications, sometimes called "gravity heating systems",
heating the heat
exchange fluid in a heat exchanger disposed near the lowest point of a heat
exchange system causes
the heated heat exchange fluid to rise through the system toward heat sinks in
the heating circuit.
As the heated fluid dissipates heat through the heat sinks, the fluid cools,
causing the cooled heat
exchange fluid to descend toward the heat exchanger. While such systems are
known to operate
without the need for a mechanical pump to drive flow, they may be susceptible
to the formation
of vapour, such as steam, that can create unwanted noise and premature damage
to system
components. Further, such systems may be difficult to design and install, with
numerous
Date Recue/Date Received 2021-03-19
3
constraints on the position and sizing of system components. Despite existing
approaches, barriers
remain to circulating flow without the need for a mechanical pump.
[0012] In one aspect, there is a need to drive flow in a fluid heat exchange
system without using a
mechanical pump. In another aspect, there is a need for flexibility in the
relative position of
components in a fluid heat exchange system. In still another aspect, there is
a need for a heat
exchanger that can drive sufficient flow while inhibiting the formation of
vapour in the heat
exchange fluid.
[0013] The present disclosure provides a system for heat exchange in which
temperature
differentials in a fluid heat exchange system drive flow of a heat exchange
fluid through the
system. In another embodiment, the present disclosure provides a heat
exchanger comprising a
plurality of heat exchange conduits arranged in parallel between a supply
manifold and a return
manifold. When in fluid communication with a heat exchange circuit and filled
with a heat
exchange fluid, heating the heat exchanger drives the heat exchange fluid to
flow through the heat
exchanger and the heat exchange circuit.
[0014] In this description, the term "parallel" refers to an arrangement in
which fluid in the
plurality of the heat exchange conduits flows concurrently in multiple heat
exchange conduits
between the return manifold and the supply manifold regardless of the relative
orientation or
geometry of the conduits, as opposed to a "series" arrangement in which fluid
exiting from one
heat exchange conduit flows into another heat exchange conduit before exiting
the heat exchanger
via the supply manifold. Thus, while the arrangements contemplated in this
disclosure include
implementations in which heat exchange conduits are arranged in a
geometrically parallel
formation, unless provided otherwise the term "parallel" should not be
understood as limited to
such a geometric arrangement.
[0015] In another embodiment, the present disclosure provides a method for
fluid heat exchange
in which temperature differentials in a fluid heat exchange system drive flow
of a heat exchange
fluid through the heat exchange system.
[0016] In at least one embodiment, a heat exchanger is provided. The heat
exchanger is
connectable to a heat exchange circuit, and comprises: a supply manifold for
supplying heated heat
exchange fluid to the heat exchange circuit; a return manifold for returning
cooled heat exchange
Date Recue/Date Received 2021-03-19
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fluid from the heat exchange circuit; and a plurality of heat exchange
conduits arranged in parallel
between the supply manifold and the return manifold, for heating and driving
flow of the heat
exchange fluid from the return manifold to the supply manifold when heated.
Each heat exchange
conduit has: a supply check valve fluidly coupling the heat exchange conduit
to the supply
manifold and permitting one-way flow from the heat exchange conduit to the
supply manifold
when the heat exchange fluid expands within the heat exchange conduit; and a
return check valve
fluidly coupling the heat exchange conduit to the return manifold and
permitting one-way flow
from the return manifold into the heat exchange conduit.
[0017] In at least another embodiment, a heat exchange system may be provided.
The heat
exchange system may comprise: a heat exchange circuit for supplying heat; a
heat exchanger in
fluid communication with the heat exchange circuit, the heat exchanger
comprising: a supply
manifold for supplying heated heat exchange fluid to the heat exchange
circuit; a return manifold
for returning cooled heat exchange fluid from the heat exchange circuit; and a
plurality of heat
exchange conduits arranged in parallel between the supply manifold and the
return manifold, for
heating and driving flow of the heat exchange fluid from the return manifold
to the supply manifold
when heated. Each heat exchange conduit has: a supply check valve fluidly
coupling the heat
exchange conduit to the supply manifold and permitting one-way flow from the
heat exchange
conduit to the supply manifold when the heat exchange fluid expands within the
heat exchange
conduit; and a return check valve fluidly coupling the heat exchange conduit
to the return manifold
and permitting one-way flow from the return manifold into the heat exchange
conduit; and a
reservoir in fluid communication with the heat exchanger for retaining heat
exchange fluid, the
reservoir extending above the heat exchanger and the heat exchange circuit.
[0018] In yet another embodiment, a method is provided for heat exchange in a
fluid heat exchange
system having a heat exchanger and a heat exchange circuit in fluid
communication with the heat
exchanger, the method comprising activating a heat source having a temperature
above the
temperature of a heat exchange fluid in the heat exchange system to heat a
heat exchange fluid in
the heat exchanger, the heat exchanger comprising: a supply manifold for
supplying heated heat
exchange fluid to the heat exchange circuit; a return manifold for returning
cooled heat exchange
fluid from the heat exchange circuit; and a plurality of heat exchange
conduits arranged in parallel
between the supply manifold and the return manifold for heating and driving
flow of the heat
Date Recue/Date Received 2021-03-19
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exchange fluid from the return manifold to the supply manifold. Each heat
exchange conduit has:
a supply check valve fluidly coupling the heat exchange conduit to the supply
manifold and
permitting one-way flow from the heat exchange conduit to the supply manifold
when the heat
exchange fluid expands within the heat exchange conduit; and a return check
valve fluidly coupling
the heat exchange conduit to the return manifold and permitting one-way flow
from the return
manifold into the heat exchange conduit.
[0019] Each of the heat exchange conduits may be formed of 1/4 inch diameter
copper piping. The
supply manifold and the return manifold may be formed of 1/2 inch diameter
copper piping.
[0020] In operation, the supply manifold may be disposed above the return
manifold. The heat
exchange fluid may liquid. The heat exchange fluid may be water.
[0021] In at least one embodiment, the heat exchange conduits are sized to
prevent the formation
of vapour when the heat exchanger is heated by a heat source.
[0022] The supply manifold and the return manifold may be in fluid
communication with opposite
ends of the heat exchange circuit and heat may be applied to the heat
exchanger, and the heat
exchange fluid may be driven from at least one of the plurality of heat
exchange conduits into the
supply manifold, through the heat exchange circuit, into the return manifold,
and into at least one
of the plurality of heat exchange conduits.
[0023] When the heat exchanger is in fluid communication with the heat
exchange circuit, the heat
exchanger may be disposed substantially above the heat exchange circuit.
[0024] The heat exchanger may be connectable to a reservoir for containing
heat exchange fluid.
[0025] FIG. 1 illustrates an embodiment of a heat exchange system 100. The
heat exchange system
100 comprises a heat exchanger 110, a reservoir 140, and a circuit 150. The
heat exchanger 110 is
in fluid communication with the reservoir 140 and the circuit 150.
[0026] The heat exchanger 110 comprises a supply manifold 112 for supplying
heated heat
exchange fluid, a return manifold 114 for receiving cooled heat exchange fluid
and a plurality of
heat exchange conduits 116 arranged in parallel between the supply manifold
112 and the return
manifold 114 for heating the heat exchange fluid. Each heat exchange conduit
116 has a supply
Date Recue/Date Received 2021-03-19
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check valve 118 fluidly coupling the heat exchange conduit 116 to the supply
manifold 112 and
permitting one-way flow from the heat exchange conduit 116 to the supply
manifold 112, and a
return check valve 120 fluidly coupling the heat exchange conduit 116 to the
return manifold 114
and permitting one-way flow from the return manifold 114 into the heat
exchange conduit 116.
[0027] The heat exchanger 110 is heated by a heat source 180, and the circuit
150 dissipates heat
from the heat exchange fluid into the environment. As described below in
greater detail, the heat
source 180 operates at a temperature Th and heats the heat exchange fluid
within each heat
exchange conduit 116. As it gets hotter, the heat exchange fluid expands and
thereby flows through
the supply check valve 118 into the supply manifold 112 at a temperature T.
The supply
temperature Ts of the heat exchange fluid is lower than the operating
temperature Th of the heat
source. The fluid then enters the circuit 150, and continues, where it
progressively loses heat
through dissipation into the environment, which may have an ambient
temperature of Te. The heat
exchange fluid is cooled and, as a result, contracts as it travels through the
circuit 150. The cooled
fluid returns to the return manifold 114 of the heat exchanger at a
temperature Tr, which is lower
than the supply temperature Ts, and into the plurality of heat exchange
conduits 116 through their
respective return check valves 120.
[0028] The heat exchange circuit 150 is shown as a closed loop; that is, the
fluid supplied by the
supply manifold 112 is returned to the return manifold 114. However, in an
alternative
embodiment the circuit may be an open-loop circuit. For example, the heat
exchange circuit may
comprise a low-temperature reservoir in fluid communication with the return
manifold, and a high
temperature reservoir in fluid communication with the supply manifold but
fluidly independent of
the low temperature reservoir, and the heat exchanger when heated may drive
flow of the heat
exchange fluid from the low temperature reservoir to the high temperature
reservoir.
[0029] Each heat exchange conduit 116 is in fluid communication with the
supply manifold 112
by a supply check valve 118 that permits one-way flow of the heat exchange
fluid from the heat
exchange conduit 116 into the supply manifold 112. Each heat exchange conduit
116 is further in
fluid communication with the return manifold 114 by a return check valve 120
that permits one-
way flow of the heat exchange fluid from the return manifold into the heat
exchange conduit. When
the heat exchanger 110 is in fluid communication with to the circuit 150,
these supply check valves
118 and return check valves 120 permit one-way flow of heat exchange fluid
from the return
Date Recue/Date Received 2021-03-19
7
manifold through the heat exchange conduits and into the supply manifold. Any
suitable check
valve, such as the check valves illustrated in FIGS. 2 and 3 may be selected.
Advantageously, the
opening pressure, that is, the pressure differential between the upstream and
downstream heat
exchange fluid required to open each supply check valve 118 and return check
valve 120, may be
minimized to prevent the accumulation of vapour within the heat exchange
conduits 116 or to
avoid impeding flow through the heat exchange system 100.
[0030] When the heat source 180 is active, heat is supplied to fluid within
each of the heat
exchange conduits 116. As the fluid is heated, it begins to expand outward.
The return check valve
120 prevents the expanding heat exchange fluid from expanding into the return
manifold 114,
while the supply check valve permits the expanding heat exchange fluid to
expand into the supply
manifold 112. The heat source 180 may be a gas heater, solid fuel heater,
solar heater, wood stove,
fireplace, the evaporator of a heat pump, or other suitable heat source.
[0031] The supply manifold 112 is in fluid communication with the reservoir
140 and the inlet of
the circuit 150. For example, the return manifold and supply manifold 112 may
comprise a welded
coupling to the reservoir 140 and the circuit 150, or a threaded coupling
permitting removable
coupling.
[0032] In the embodiment illustrated in FIG. 1, the reservoir 140 comprises a
column 142 that
extends above the supply manifold 112 of the heat exchanger 110 and also above
any other heat
exchange fluid within the heat exchange system 100 to prevent siphoning of
heat exchange fluid
out of the heat exchange system 100. The reservoir stores heat exchange fluid
for the heat exchange
system 100 and accommodates fluctuations in the volume of heat exchange fluid
within the heating
system 100. Fluctuations may arise due to evaporation if the heat exchange
system 100 is not
completely sealed, or to expansion and contraction of the heat exchange fluid
within the heat
exchange system 100 in response to aggregate increases or decreases in the
temperature of the heat
exchange fluid. Relative to its unheated state, the aggregate temperature of
the heat exchange fluid
will increase when the heat source 180 applies heat to the heat exchange
system 100. As a result
of the addition of heat, the aggregate volume of the heat exchange fluid in
the heat exchange system
may increase. These volume fluctuations may be accommodated by the reservoir
140, where the
fluid is free to rise and fall in response.
Date Recue/Date Received 2021-03-19
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[0033] The reservoir may comprise a looking glass-type fluid level display
144, a level sensor or
other level gauge to facilitate inspection. The column 142 extends above the
supply manifold 112
of the heat exchanger 110 so that any vapour generated within the heat
exchanger will rise into the
column and, if not attenuated, can escape through an opening in the column 142
above the
maximum fill line of the reservoir 140. In the illustrated embodiment, the
column comprises a fill
cap 146 with a pressure valve to release vapour from the heat exchange system
100 and for adding
fluid to the reservoir 140.
[0034] The heat exchange circuit 150 may be connected to the heat exchanger
110 by threaded
couplings, other removable couplings, or fixed couplings such as a soldered
fit to supply manifold
112 and return manifold 114. The heat exchange circuit 150 may be constructed
from any suitable
material such as a heat resistant composite tubing, copper piping, steel
piping or other suitable
material. The heat exchange circuit 150 may be insulated along its length,
except at one or more
heat sink locations. For example, in the embodiment illustrated in FIG. 1, the
heat exchange circuit
150 comprises a hot water heater 152 for supplying hot water and an in-floor
radiant heating loop
158 for heating a floor 190 below the heat exchanger 110. The hot water heater
152 comprises a
hot water tank 154 and a hot water heating loop 156 inline with the heat
exchange circuit 150 for
heating water in the hot water tank 154. However, any other type of heat sink
may be connected
to the heat exchange circuit 150, such as radiators, forced air heaters,
dryers and heat pump
condensers.
[0035] The size and number of the heat exchange conduits 116 is selected based
on the type of
heat source, the properties of the heat exchange fluid, and the desired heat
output of the heat
exchanger. As previously described, it may be advantageous to inhibit the
formation of vapour
within the heat exchange fluid. Accordingly, for a given heat source, heat
exchange fluid and
expected return temperature Tr, the length of each heat exchange conduit may
be selected to ensure
that the maximum temperature of the heat exchange fluid within each heat
exchange conduit 116
remains below the boiling point of the heat exchange fluid. For example, if
the heat exchange fluid
is water having a boiling point of 100 C, and the expected maximum return
temperature Tr of the
water is 10 C, then each heat exchange conduits 116 may be sized such that,
for a given operating
temperature of the heat source Th, the water will gain less than 90 C within
the heat exchange
conduit 116. As a result, the supply temperature Ts of the heat exchange fluid
may be limited by
Date Recue/Date Received 2021-03-19
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its boiling point. Accordingly, the length of each heat exchange conduit 116
may be
advantageously selected to avoid heating the heat exchange fluid beyond its
boiling point given
the expected operating temperatures of the heat exchange system 100. It will
be appreciated that,
for a heat exchange conduit 116 having a given profile, increasing the length
heated by the heat
source 180 will lead to greater temperature gains and thus a higher supply
temperature Ts of the
heat exchange fluid for a given return temperature Tr.
[0036] The width or diameter of each heat exchange conduit 116 may be selected
to provide
sufficient throughput of heat exchange fluid while mitigating the formation of
local temperature
peaks that exceed the boiling point of the heat exchange fluid. In one
implementation, the heat
exchange conduits 116 may be formed of 1/4 inch diameter flexible copper
tubing. However, other
sizes and materials may be used depending on the application.
[0037] A larger cross-sectional area for the heat exchange conduit 116
provides a larger heat
exchange surface per length of heat exchange conduit, the radial temperature
gradient will be
correspondingly larger. As a result, the heat exchange fluid at the centre of
cross-sectional area
will be colder as the size of the cross-sectional area increases, if localized
temperature peaks are
to be maintained below the boiling point of the heat exchange fluid. A smaller
cross-sectional area
for the heat exchange conduit 116 may lead to more even heating, and a higher
temperature in the
heat exchange fluid toward the centre of the cross-sectional area while
maintaining localized
temperature peaks below the boiling point. Further, decreasing the size of the
cross-sectional area
may increase the sensitivity of the heat exchange fluid to expansion within
the heat exchange
conduit 116, and to mitigate the formation of large, potentially destructive
vapour pockets within
the heat exchange fluid.
[0038] For a given size and length of each heat exchange conduit 116, a given
difference between
the supply temperature Ts and return temperature Tr, and a given temperature
Th of the heat source,
the heat output of the heat exchanger 110 can be increased or decreased by
increasing or
decreasing, respectively, the number of heat exchange conduits 116 arranged in
series. For
example, the heat exchanger 110 shown in FIG. 1 comprises twelve heat exchange
conduits 116.
However, the heat output of the heat exchanger 110 may be increased or
decreased by increasing
or decreasing, respectively, the number of heat exchange conduits 116 arranged
between the
supply manifold 112 and return manifold 114.
Date Recue/Date Received 2021-03-19
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[0039] The heat exchange conduits 116 may be constructed of any suitable
material. For example,
the heat exchange conduits may be constructed of copper tubing, which exhibits
relatively high
heat conductivity. Alternatively, the heat exchange conduits 116 may be
constructed of steel,
stainless steel or other material capable of withstanding heat from the heat
source 180 while
ensuring sufficient heat conductivity, strength and other properties for an
application.
[0040] The supply manifold 112 and, similarly, the return manifold 114, may be
made of copper
tubing or other suitable material. The supply manifold 112 may be sized based
on the size
constraints of the heat source 180, desired spacing between each of the heat
exchange conduits
116 and to provide sufficient fluid flow therethrough. For example, the supply
manifold 112 and
return manifold 114 may be constructed of 1/2 inch copper piping. However,
other materials and
sizes may be selected.
[0041] The heat exchanger 110 may comprise a stand, brackets or anchoring
fixtures (not shown)
for mounting or positioning the heat exchanger 110 to or near the heat source
180. For example,
the heat exchanger 110 may comprise brackets for mounting to the rear of a
wood stove. The heat
exchanger 110 is shown in FIG. 1 in an upright or vertical orientation; that
is, the heat exchange
conduits 116 extend substantially vertically from the return manifold 114 to
the supply manifold
112 and the supply manifold 112 is disposed above the return manifold 114. In
the depicted
arrangement, the heat exchanger 110 may further exploit the thermosiphon
effect in which the
tendency of warmer fluids to rise and colder fluids to fall may contribute to
driving flow within
the heat exchanger 110 and the heat exchange circuit 150 beyond. Further, even
if the heat
exchanger 110 has been sized to mitigate vapour formation, occasional vapour
may nevertheless
form. The substantially vertical orientation of the heat exchanger provides a
flow path for any
vapour formed within the heat exchange conduits 116 to rise and exit through
the supply check
valves 118 and flow through the reservoir 140, as described below. In another
aspect, the heat
exchanger 110 may be oriented substantially horizontally or at an incline
relative to horizontal.
However, it will be appreciated that orienting the heat exchanger 110 so that
the supply manifold
112 is level with the return manifold 114 may attenuate the thermosiphon
effect. Further, if the
supply manifold lies below the return manifold 114, then the thermosiphon
effect may oppose flow
through the heat exchanger 110 and entrap vapour against the return check
valve 120 within each
heat exchange conduit 116.
Date Recue/Date Received 2021-03-19
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[0042] The heat exchanger 110 may be disposed above or below the heat exchange
circuit 150.
For example, as shown in FIG. 1, the heat exchanger 110 is shown disposed
above a lower floor
190 and below an upper floor 192, while the heat exchange circuit 150 runs
above the upper floor
192 and beneath the lower floor 190. However, substantially all of the heat
exchange circuit 150
may be disposed at a level below that of the heat exchanger 110 except for any
sections to connect
to the supply manifold 112 and the return manifold 114, or substantially above
the heat exchanger
150, while maintaining flow through the heat exchange circuit 150 when
sufficient heat is provided
to the heat exchange fluid in the heat exchanger 110.
[0043] Referring now to FIG.2, an embodiment of a supply check valve 218 as
may be
implemented in a heat exchanger is shown. The supply check valve 218 comprises
a T-section 230
having arm segments 232 sized to receive adjacent segments of the supply
manifold 112, a sleeve
234 inserted into a foot segment 236 of the T-section 230, a cap 238 inserted
over the end of the
sleeve 234 having an aperture 240 therein, a coupling 242 having an unthreaded
male end 244
inserted into the aperture 240, and a threaded male end 246 opposite and in
fluid communication
with the unthreaded male end 244, a tubular seat 248 retained within the
unthreaded male end 244,
a tubular stopper 250 disposed opposite the tubular seat 248 by a pair of
retainers 252, a ball 254
movably retained between the tubular seat 248 and the tubular stopper 250, a
spring 256 disposed
within the tubular stopper 250, a nut 258 engaged with the threaded male end
246, and a crimping
ring 260 for receiving and retaining an end of the heat exchange conduit 116
when the nut 258 is
tightened.
[0044] The T-Section 230, sleeve 234, cap 238, tubular seat 248, tubular
stopper 250, coupling
242, and nut 258 may be formed of any suitable heat resistant material, such
as copper, iron, steel
or a polymer. The crimping ring 260 may be made of any suitably pliable and
soft material, such
as brass, rubber or silicon to create a seal around the heaty exchange conduit
116 when the nut 258
is tightened. The ball 254 may be formed of glass, metal or other material
advantageously capable
of withstanding heat, corrosion and impact. For example, the ball 254 may be a
1/4 inch 440C
stainless steel ball. In another example, the ball 254 may be a glass ball.
[0045] The tubular stopper 250 is disposed opposite and apart from the tubular
seat 248 by a
distance that is selected to permit the ball 254 to travel away from the
tubular seat 248, and thus
open a flow path through the supply check valve 118 in the direction shown by
the arrow 262, but
Date Recue/Date Received 2021-03-19
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less than the diameter of the ball so that the ball 254 is retained between
the tubular stopper 250
and the tubular seat 248.
[0046] The supply check valve 218 may comprise the optional spring 256 within
the tubular
stopper 250 to absorb impact when the ball 254 is driven away from the tubular
seat 248 toward
the tubular stopper 250. Further, in applications where the weight of the ball
254 alone cannot be
relied on to close the flow path, the spring 256 may bias the ball 254 against
the tubular seat 248
and thereby close the flow path. In such applications, the ball 254 would open
a flow path
whenever the pressure differential in the heat exchange fluid upstream and
downstream of the ball
254 meets or exceeds the opening pressure, that is, the pressure required to
overcome the forces
biasing the ball 254 against the tubular seat 248. To avoid inhibiting flow
through the supply check
valve 218 and to avoid causing pressure build-up upstream of the ball 254, the
spring 256 may be
advantageously selected to apply minimal bias to the ball against the tubular
seat 248 when the
ball 254 is in the closed position.
[0047] Referring now to FIG. 3, an embodiment of a return check valve 320 as
may be
implemented in a heat exchanger is shown. The return check valve 320 comprises
a T-section 330
having arm segments 332 sized to receive adjacent segments of the supply
manifold 112, a sleeve
334 partially inserted into a foot segment 336 of the T-section 330, a first
coupling 338 having a
narrow end 340 connected over the protruding section of the sleeve 334 and a
wide end 342, a cap
344 inserted over the wide end 342 of the first coupling 338 having an
aperture 346 therein, a
second coupling 348 having an unthreaded male end 350 inserted into the
aperture 346, and a
threaded male end 352 opposite and in fluid communication with the unthreaded
male end 350, a
ball 354 movably retained between the threaded male end 352 and the sleeve
334, a nut 356
engaged with the threaded male end 352, and a crimping ring 358 for receiving
and retaining an
end of the heat exchange conduit 116 when the nut 356 is tightened.
[0048] The T-section 330, sleeve 334, first coupling 338, cap 344, second
coupling 348 and nut
356 may be formed of any suitable heat resistant material, such as copper,
iron, steel or a polymer.
The crimping ring 358 may be made of any suitably pliable and soft material,
such as brass, rubber
or silicon to create a seal around the heat exchange conduit 116 when the nut
356 is tightened. The
ball 354 may be formed of glass, metal or other material advantageously
capable of withstanding
heat, corrosion and impact.
Date Recue/Date Received 2021-03-19
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[0049] The sleeve 334 serves as a seat for the ball 354 when the return check
valve 320 is closed.
In the open position, the ball 354 moves away from the tubular sleeve 334 to
establish the flow
path indicated by the arrow 360. The first coupling 338 further comprises a
widening section 341
that directs the ball 354 toward the sleeve 334 when the ball falls toward it
or is pushed against it.
In applications where gravity alone cannot be relied on to cause the ball to
fall toward the sleeve
334, such as when the heat exchanger 110 is oriented horizontally, then the
return check valve 320
may further comprise a spring (not shown) to bias the ball 354, as in the
supply check valve 218
illustrated in FIG. 2. Further, it will be appreciated that the supply check
valve 218 of FIG. 2 may
be rearranged as a return check valve, while the return check valve 320 of
FIG. 3 may be rearranged
as a supply check valve.
[0050] Embodiments of the present disclosure provide for heat exchange with a
heat exchanger
comprising a plurality of heat exchange conduits arranged in parallel between
a supply manifold
and a return manifold. The heat exchanger is in fluid communication with a
heat exchange circuit.
Each heat exchange conduit is in fluid communication with the supply manifold
by a supply check
valve that permits fluid to flow from the heat exchange conduit into the
supply manifold and to
the return manifold by a return check valve that permit fluid to flow from the
return manifold into
the heat exchange conduit. When the heat exchanger is filled with fluid and
heat is applied to the
heat exchanger, the heat exchange fluid in each heat exchange conduit heats
up, expands and
travels through the supply check valve into the supply manifold. The fluid
exits the supply
manifold into the heat exchange circuit, where it loses heat and contracts,
returns into the return
manifold and then through the return check valve of each heat exchange
conduit.
[0051] Referring again to FIG. 1, as an opening condition, the heat exchange
system 100 is filled
with heat exchange fluid through fill cap 146 of the reservoir 140 to the
desired level, that is, above
the highest point of any heat exchange liquid elsewhere within the heat
exchange system 100. This
may be gauged using the fluid level display 144 on the column 142.
[0052] Once the heat source 180 is actuated, it heats the heat exchange
conduits 116 and the heat
exchange fluid contained therein. As the fluid within a heat exchange conduit
116 is heated, it
gains pressure until it can expand. The return check valve 120 prevents the
fluid from expanding
from the heat exchange conduit 116 into the return manifold 114. Instead, when
the pressure
differential between the fluid within the heat exchange conduit 116 and the
supply manifold 112
Date Recue/Date Received 2021-03-19
14
reaches the opening pressure of the supply check valve 118, the supply check
valve 118 opens,
permitting the fluid to expand into the supply manifold 112 from which it
continues into the heat
exchange circuit 150. As the fluid within each of the heat exchange conduits
116 continues to
expand into the supply manifold 112, downstream fluid is driven further
through the heat exchange
circuit 150.
[0053] As the fluid travels through the heat exchange circuit 150 from the
supply manifold 112
toward the return manifold 114, it loses heat into the environment,
particularly in any designated
heat sinks, such as the hot water heater 152 and in-floor heating loop 158
shown in FIG. 1. The
fluid may also experience heat loss elsewhere in the heat exchange circuit 150
wherever the
environment is colder than the heat exchange fluid. As the fluid cools, it
seeks to contract. The
return check valves 120 prevent this contraction from drawing fluid from the
heat exchange
conduits 116 through the return manifold 114. Instead, the expanding heated
fluid from the supply
manifold 112 continually displaces and drive the colder heat exchange fluid
toward the return
manifold 114. When the pressure differential in the heat exchange fluid
between the return
manifold 114 and each heat exchange conduit 116 reaches the opening pressure
of the return check
valve 120, the return check valve 120 opens and the heat exchange fluid enters
the heat exchange
conduit 116 from the return manifold 114. After re-entering the heat exchange
conduits 116, the
heat exchange fluid is reheated and the cycle resumes.
[0054] The heat exchanger 110 thus develops a thermosiphon in which applying
sufficient heat to
the heat exchanger 110 drives flow of heat exchange fluid through the heat
exchange system
without the need for a mechanical pump.
[0055] In one implementation, a heat exchange system was constructed
comprising a heat
exchanger, a reservoir, and a heat exchange circuit. The heat exchanger was in
fluid
communication with the reservoir and the heat exchange circuit. The heat
exchanger comprised 10
heat exchange conduits constructed of flexible 1/4 inch diameter copper pipes.
The heat exchange
conduits were arranged in parallel between a supply manifold and a return
manifold, with a supply
check valve and a return check valve fluidly coupling each heat exchange
conduit to the supply
manifold and return manifold, respectively. The supply manifold and the return
manifold were
constructed of 1/2 inch diameter copper piping. The heat exchange circuit was
formed of a 30-metre
length of 5/8 inch rubber hose. The heat exchanger was disposed in a
substantially upright
Date Recue/Date Received 2021-03-19
15
orientation adjacent a wood stove, and above the heat exchange circuit. The
reservoir, the heat
exchanger and the heat exchange circuit were filled with water, and the wood
stove was lit. With
the wood stove heated to approximately 500 C, the heat exchanger circulated
water through the
heating system without the need for a mechanical pump.
[0056] The embodiments in this disclosure have been described in the context
of a particular
application; however, their implementation is not so limited. These
embodiments are meant to be
exemplary only. The heat exchanger may be used in other heat exchange
applications, whether for
cooling or heating.
[0057] It will be appreciated that individual features having been described
in the context of
separate embodiments may also be provided in combination in a single
embodiment. Further,
individual features having been described in the context of a single
embodiment may also be
provided separately or in any suitable subcombination.
[0058] Various embodiments having been thus described in detail by way of
example, it will be
apparent to those skilled in the art that alternatives, variations and
modifications may be made
without departing from the invention.
Date Recue/Date Received 2021-03-19
