U.S. patent application number 11/889462 was filed with the patent office on 2009-01-22 for irrigation reservoir cooling system.
Invention is credited to Raymond Paul Del Greco, Marco Guglietti.
Application Number | 20090019876 11/889462 |
Document ID | / |
Family ID | 40263755 |
Filed Date | 2009-01-22 |
United States Patent
Application |
20090019876 |
Kind Code |
A1 |
Guglietti; Marco ; et
al. |
January 22, 2009 |
Irrigation reservoir cooling system
Abstract
A combined space-cooling and irrigation system and method of
operation. The system is operated by an automated control unit
specifically programmed to manage cooling and irrigation needs as
follows. When irrigation water is needed, the system pumps cool
water from a municipal water supply, a well, or a deep pond,
through a heat exchanger on the way to a reservoir. The water
pumped through the heat exchanger cools fluid in a separate closed
circuit. The cooled fluid in the closed circuit is then used for
cooling purposes, for example, to cool the air circulated through a
house or building using a commercially available fan coil unit. The
reservoir releases collected water for irrigation purposes at
appropriate times.
Inventors: |
Guglietti; Marco; (Oakville,
CA) ; Del Greco; Raymond Paul; (Beeton, CA) |
Correspondence
Address: |
WELSH & FLAXMAN LLC
2000 DUKE STREET, SUITE 100
ALEXANDRIA
VA
22314
US
|
Family ID: |
40263755 |
Appl. No.: |
11/889462 |
Filed: |
August 13, 2007 |
Current U.S.
Class: |
62/260 ;
165/47 |
Current CPC
Class: |
F24F 5/0046 20130101;
Y02B 10/40 20130101; Y02B 10/20 20130101; Y02B 10/24 20130101; F24F
2005/0057 20130101; F25D 1/02 20130101 |
Class at
Publication: |
62/260 ;
165/47 |
International
Class: |
F25B 27/00 20060101
F25B027/00; F24F 3/06 20060101 F24F003/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2007 |
CA |
2,593,906 |
Claims
1. A space-cooling and irrigation system that utilizes ground water
for cooling and irrigation purposes comprising: a primary heat
exchanger; a water holding tank comprising a means of discharging
water for irrigation purposes; a water conduit connected to a
source of ground water and said water holding tank; and a closed
fluid circuit operable to cool a space; wherein said primary heat
exchanger is operable to exchange heat between said water conduit
and said closed fluid circuit.
2. The space-cooling and irrigation system of claim 1 wherein said
water conduit is provided with at least one pump operable to move
water from said source of ground water through said water
conduit.
3. The space-cooling and irrigation system of claim 1 wherein said
water conduit is provided with an optionally usable first branch,
said first branch passing though said primary heat exchanger; and
said closed fluid circuit is provided with an optionally usable
first branch, said first branch passing through said primary heat
exchanger.
4. The space-cooling and irrigation system of claim 1 further
comprising a means of controlling said system automatically, said
means of control comprising a programmable controller unit
5. The space-cooling and irrigation system of claim 1 wherein said
closed fluid circuit comprises: a heat-transfer fluid, said
heat-transfer fluid filling said closed fluid circuit; at least one
pump operable to move said heat-transfer fluid around said closed
fluid circuit; at least one fluid chilling means operable to cool
said heat-transfer fluid; and at least one space-cooling means
operable to cool said space; wherein said heat-transfer fluid is
cooled by at least one of said fluid chilling means and said heat
exchanger; and wherein said space-cooling means uses said
heat-transfer fluid to cool air and circulates said air through
said space.
6. The space-cooling and irrigation system of claim 1 wherein said
water conduit comprises an optionally usable second branch, said
second branch passing though a secondary heat exchanger.
7. The space-cooling and irrigation system of claim 6 wherein said
secondary heat exchanger is a dehumidifier.
8. The space-cooling and irrigation system of claim 6 further
comprising: a tertiary heat exchanger; a second fluid circuit
comprising: i) an outdoors heat exchanger operable to exchange heat
between said second fluid circuit and outdoors environment; and ii)
a pump operable to circulate a heat-transfer fluid around said
second fluid circuit; wherein said tertiary heat exchanger is
operable to exchange heat between said second branch and said
second fluid circuit; and wherein said second branch optionally
forms a water circuit operable to circulate water between said
tertiary heat exchanger and said secondary heat exchanger.
9. A method of operating a space-cooling and irrigation system that
utilizes ground water for cooling and irrigation purposes
comprising the steps of: pumping water from a source of ground
water through a water conduit, said water flowing through a primary
heat exchanger and flowing into a water holding tank comprising a
means of discharging said water for irrigation purposes; pumping a
heat-transfer fluid through a closed fluid circuit operable to cool
a space, said heat-transfer fluid flowing through said primary heat
exchanger wherein heat exchanged between said heat-transfer fluid
and said water cools said heat-transfer fluid.
10. A method of operating a space-cooling and irrigation system
that utilizes ground water for cooling and irrigation purposes,
said space-cooling and irrigation system comprising a primary heat
exchanger, a water holding tank comprising a means of discharging
water for irrigation purposes, a water conduit connected to a
source of ground water and said water holding tank, and a closed
fluid circuit operable to cool a space, comprising the step of:
operating said space-cooling and irrigation system to maximize heat
exchange between said closed fluid circuit and said water conduit
when temperature of said space exceeds a predetermined temperature,
when temperature of said ground water is lower than a predetermined
temperature and when said water holding tank has water storage
capacity, said operation comprising the steps of: i) pumping water
from a source of ground water through said water conduit, said
water flowing through said primary heat exchanger and flowing into
said water holding tank; ii) pumping a heat-transfer fluid through
said closed fluid circuit, said heat-transfer fluid flowing through
said primary heat exchanger wherein heat exchanged between said
heat-transfer fluid and said water cools said heat-transfer
fluid;
11. The method of operating a space-cooling and irrigation system
of claim 10 wherein said closed fluid circuit comprises at least
one fluid chilling means operable to cool said heat-transfer
fluid.
12. The method of operating a space-cooling and irrigation system
of claim 11 wherein said step of operating said space-cooling and
irrigation system to maximize heat exchange further comprises the
step of actuating said at least one fluid chilling means to cool
said heat-transfer fluid if additional cooling of said
heat-transfer fluid is required.
13. The method of operating a space-cooling and irrigation system
of claim 12 further comprising the step of: operating said closed
fluid circuit as a stand alone cooling system when temperature of
said space exceeds a predetermined temperature and when temperature
of said ground water is not lower than a predetermined temperature
or said water holding tank does not have water storage capacity,
said operation comprising the steps of: i) pumping a heat-transfer
fluid through said closed fluid circuit; and ii) actuating said at
least one fluid chilling means to cool said heat-transfer
fluid.
14. A method of operating a space-cooling and irrigation system
that utilizes ground water for cooling and irrigation purposes,
said space-cooling and irrigation system comprising: a) a primary
heat exchanger, b) a water holding tank comprising a means of
discharging water for irrigation purposes, c) a water conduit
connected to a source of ground water and said water holding tank,
and d) a closed fluid circuit operable to cool a space, comprising
the steps of: a) determining whether temperature of said space
exceeds a predetermined temperature, b) determining whether
temperature of said ground water is lower than a predetermined
temperature, c) determining whether said holding tank has water
storage capacity, d) if temperature of said space exceeds a
predetermined temperature and temperature of said ground water is
lower than a predetermined temperature and water holding tank has
water storage capacity: i) pumping water from a source of ground
water through said water conduit, said water flowing through said
primary heat exchanger and flowing into said water holding tank,
ii) pumping a heat-transfer fluid through said closed fluid
circuit, said heat-transfer fluid flowing through said primary heat
exchanger wherein heat exchanged between said heat-transfer fluid
and said water cools said heat-transfer fluid.
15. The method of operating a space-cooling and irrigation system
of claim 14 wherein said closed fluid circuit comprises at least
one fluid chilling means operable to cool said heat-transfer
fluid.
16. The method of operating a space-cooling and irrigation system
of claim 15 further comprising the step of actuating said at least
one fluid chilling means to cool said heat-transfer fluid if
additional cooling of said heat-transfer fluid is required.
17. The method of operating a space-cooling and irrigation system
of claim 9 further comprising the step of periodically discharging
said water in said water holding tank for irrigation purposes.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a combined space-cooling
and irrigation system.
BACKGROUND
[0002] Ground temperatures four feet below grade are a constant
50.degree. F. to 56.degree. F. from the east coast of North America
to the west coast and from Atlanta Ga. to Sudbury, Ontario. This
vast area has cool ground temperatures and hot summers with
attendant cooling and irrigation requirements.
[0003] Cooling systems which make use of the relative coolness of
underground water sources, such as wells or municipal water mains,
are well known in the art. For example, U.S. Pat. Nos. 4,375,831,
4,946,110, 5,727,621, 6,041,613 and 6,688,129 disclose the concept
of using the coolness of ground water to acclimatize living space.
Also known in the art are systems for controlling irrigation, for
example, U.S. Pat. Nos. 4,134,269, 4,393,890 and 4,693,419.
However, none of the above patents combine a space cooling system,
which makes use of underground water for cooling needs, with an
irrigation system.
[0004] U.S. Pat. No. 5,140,829 to Barwacz teaches a space-cooling
system using a heat exchanger for ground water that has been
slightly chilled by a heat pump. The heat pump cools the incoming
ground water and uses the return flow of warmed ground water, or at
least a portion of the return flow, to evaporate the heat pump's
refrigerant gas. The heated discharge water can be used as
pre-heated household water, or discharged for irrigation or to a
drainage system. Barwacz therefore discloses the use of ground
water for heat exchange purposes and then using the water for
irrigation or household uses. However, there is no disclosure of a
closed loop cooling system that would allow for humidity control.
Furthermore, there is no teaching concerning a balancing of
irrigation needs and cooling needs.
SUMMARY
[0005] The present invention provides a system that makes use of
the relative coolness of underground water for cooling needs when
the water is needed for irrigation in any event.
[0006] It is an object of the present invention to provide a system
that reduces electric energy consumption for cooling purposes by
making use of the relative coolness of the ground water that is
used for irrigation purposes.
[0007] It is another object of the present invention to provide a
system that warms water to be used for irrigation purposes.
[0008] It is another object of the present invention to provide an
integrated irrigation and cooling system that operates
automatically.
[0009] It is another object of the present invention to provide a
system that reduces electric energy consumption for cooling
purposes by making use of cool external temperatures
[0010] It is yet another object of the present invention to provide
a closed loop cooling system that allows for humidity control.
[0011] The above objectives are accomplished by a novel irrigation
reservoir cooling system and method of operation. The system is
operated by an automated control unit specifically programmed to
manage cooling and irrigation needs generally as follows. [0012] 1)
When space cooling is needed, for example, during the solar heat
gain of the day, the system pumps cool underground water (ground
water) from a pressurized municipal (city) water supply, a well, or
a deep pond, through a heat exchanger on the way to a reservoir.
The water is pumped (transported) by providing the system with a
water pump or by connecting the system to a pressurized municipal
water supply. [0013] 2) The water pumped through the heat exchanger
cools fluid in a separate closed circuit. The closed circuit
includes at least one fluid chiller, which is sufficient to provide
cooling when irrigation water is not needed, for example, during
the night, on rainy days or in the winter. [0014] 3) The cooled
fluid in the closed circuit is then used for cooling purposes, for
example, to cool the air circulated through a house or building
using a commercially available fan coil unit. [0015] 4) The
reservoir releases collected water for irrigation purposes at
appropriate times, normally at night.
[0016] The irrigation reservoir cooling system is ideal for cooling
buildings that use irrigation systems such as estate homes and golf
and country clubs.
[0017] In one embodiment, the system is provided with a secondary
heat exchanger to further exploit the low temperature of ground
water for cooling purposes. The secondary heat exchanger can be any
device or system that is operable to receive and exchange heat with
a source of water, such as a dehumidifier.
[0018] In yet another embodiment, the system is provided with an
auxiliary system that exploits cool winter temperatures for cooling
purposes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Preferred embodiments of the present invention will now be
described in greater detail and will be better understood when read
in conjunction with the following drawings in which:
[0020] FIG. 1 is a schematical view of an irrigation reservoir
cooling system according to an embodiment of the invention;
[0021] FIG. 2 is a schematical view of an irrigation reservoir
cooling system according to another embodiment of the invention;
and
[0022] FIG. 3 is a schematical view of an irrigation reservoir
cooling system according to yet another embodiment of the
invention.
DETAILED DESCRIPTION
[0023] With reference to FIG. 1, the irrigation reservoir cooling
system 100 of the present invention generally comprises a water
conduit 200, a cooling circuit 300, a holding tank 400, a primary
heat exchanger 202 and a control unit 102. The direction of fluid
flow through the system is indicated by arrowheads.
[0024] In the embodiment of the invention shown in FIG. 1, the
irrigation reservoir cooling system is implemented for a building
(not shown) with an external irrigation system (not shown). In
general, water conduit 200 transports ground water, which is needed
by the irrigation system, to holding tank 400. Cooling circuit 300
operates to cool spaces within the building. Water conduit 200 and
cooling circuit 300 are thermally coupled to heat exchanger 202.
Control unit 102 monitors and actuates the water conduit and the
cooling circuit. Control unit 102 is programmed to fulfil
irrigation and cooling needs and, at the same time, maximize the
heat exchanged at primary heat exchanger 202.
[0025] A more detailed description of major components of the
irrigation reservoir cooling system follows. Water conduit 200 is a
water line that is connected to a water source 204. In the
embodiment of the invention shown in FIG. 1, water source 204
comprises a pressurized municipal water supply. In alternate
embodiments, water source 204 can be an underground well or a deep
pond. In these alternate embodiments, water conduit 200 is provided
with a pump operable to move water through the water conduit.
[0026] The water conduit extends from water source 204 to holding
tank 400. Water conduit 200 is provided with a temperature sensor
206 and a first control valve 208. Beyond first control valve 208,
water conduit 200 passes through primary heat exchanger 202
[0027] Generally, water flows though water conduit 200 as follows.
Cool underground water flows into the water conduit from water
source 204. The water flows to first heat exchanger 202, which
exploits the low temperature of the water for cooling purposes. The
water exits first heat exchanger 202 and flows to holding tank 400,
which stores the water for use by the irrigation system.
[0028] Water conduit 200 is also provided with an optionally usable
bypass circuit 210. Bypass circuit 210 provides an alternate route
for water flowing through the water conduit. The alternate route
bypasses first heat exchanger 202. Bypass circuit 210 is provided
with a second control valve 212 operable to control use of bypass
circuit 210.
[0029] Cooling circuit 300 is another major component of the
irrigation reservoir cooling system. Cooling circuit 300 is a
closed circuit provided with a first pump 302, a first temperature
sensor 304, a second temperature sensor 306, a chiller 308, a
chiller pump 310, a third temperature sensor 312, a second pump
314, at least one fan coil circuit 316 and a fourth temperature
sensor 318. In front of first pump 302, the cooling circuit passes
through first heat exchanger 202. The cooling circuit is filled
with a fluid that can be water or any commercially available heat
transfer fluid.
[0030] In the embodiment of the invention shown in FIG. 1, cooling
circuit 200 is provided with four optionally usable fan coil
circuits 316. Fan coil circuits 316 are connected in parallel to
the cooling circuit downstream of second pump 314. Each of the fan
coil circuits is provided with two control valves 322, 324 and a
fan coil unit 320. Control valves 322, 324 are operable to control
the flow of the fluid through their respective fan coil circuits
316.
[0031] The fluid is pumped through cooling circuit 300 by pumps
302, 310 and 314. Generally, the fluid flows through cooling
circuit 300 as follows. The fluid is pumped through first heat
exchanger 202, where the fluid is cooled by water flowing though
water conduit 200. The fluid is then pumped from the first heat
exchanger to chiller 308. Chiller 308 is operable to further reduce
the temperature of the fluid. The fluid is pumped from the chiller
to fan coil units 320. Fan coil units 320 are located proximate to
spaces in the building that can require cooling. Fan coil units 316
are operable to cool air and circulate said air through the spaces
that can require cooling. Next, the fluid leaves the fan coil units
and flows back to first heat exchanger 202.
[0032] The cooling circuit is also provided with an optionally
usable bypass circuit 326 that bypasses first pump 302 and first
heat exchanger 202.
[0033] Holding tank 400 comprises a water level sensor 402, an
overflow conduit 404, and a low level float 406. The capacity of
the holding tank can vary depending on irrigation needs. In the
embodiment of the invention shown in FIG. 1, holding tank 400 has a
capacity of 5000 gallons and water level sensor 402 is a
commercially available ultrasonic level indicator. The holding tank
supplies water to the irrigation system.
[0034] Water flows into holding tank 400 from water conduit 200. In
the embodiment of the invention shown in FIG. 1, the holding tank
is filled by water supplied by water conduit 200. In alternate
embodiments, water can also be supplied to holding tank by
rainwater or thaw water. If the holding tank is ever filled to
overflowing, the overflow water is directed by overflow conduit 404
to a drainage culvert 408. In alternate embodiments, the holding
tank comprises an emergency drain provided with an emergency pump
operable to rapidly pump water from the holding tank into the
culvert or a storm system.
[0035] Control unit 102 is a programmable unit with multiple signal
inputs and output. In the embodiment of the invention shown in FIG.
1, control unit 102 is a commercially available TAC Xenta.TM. 300
controller. Control unit 102 is in electronic communication with
the above described sensors, pumps, control valves, chiller and
irrigation system. The control unit is additionally in electronic
communication with an external temperature sensor 104, which
measures outdoor temperature, and at least one thermostat (not
shown) located within the building. In the embodiment of the
invention shown in FIG. 1, the control unit is connected to the
sensors, pumps, control valves, heat exchanger, chiller and
irrigation system by point to point wiring (not shown) easily
accomplished by a competent electrician. The electronic connections
can be either line voltage or 24V low voltage connections.
[0036] A description of the operation of the irrigation reservoir
cooling system 100 according to the embodiment of the invention
shown in FIG. 1 follows. A user of the irrigation reservoir cooling
system inputs (sets) a desired temperature for a space within the
building at a thermostat located within the space. When the
temperature detected by the thermostat exceeds the desired
temperature, the thermostat signals a need for cooling to control
unit 102. In response to the signal, control unit 102 executes
steps to reduce the temperature of the space to satisfy the
temperature setting of the thermostat.
[0037] First, the control unit actuates chiller pump 310 and second
pump 314, which operate to pump the fluid throughout cooling
circuit 300. Next, the control unit executes one of two set of
steps based on the availability of cool ground water and storage
capacity in holding tank 400. Control unit 102 determines whether
cool water is available based on the temperature of water from
water supply 204 at first water temperature sensor 206. Cool water
is available when the temperature of water is below a predetermined
temperature, 12.degree. C. in the present embodiment, that
represents a water temperature that is sufficiently cool to warrant
using the water as a coolant. Control unit 102 determines whether
storage capacity is available in holding tank based on input from
water level sensor 402.
[0038] If cool water is not available or storage capacity is not
available, control unit 102 operates the cooling circuit as a stand
alone cooling system. To this end, the control unit executes the
following steps. First and second control valves 208, 212 of water
conduit 200 are closed. Control unit 102 actuates chiller 308,
which is operable to cool the fluid in cooling circuit 300. The
fluid is pumped to the chiller, where the fluid is cooled, and from
the chiller to a fan coil unit 320 operable to cool the space where
the thermostat is located. The fan coil unit uses the fluid to cool
air that is then circulated though the space. The fluid leaving the
fan coil unit is pumped back to chiller 308, thus completing a loop
of cooling circuit. If the temperature of fluid at third or fourth
fluid temperature sensors 312, 318 falls below the desired
temperature, additional chilling of the fluid is no longer needed
and control 102 unit deactuates the chiller.
[0039] Alternately, if cool water is available and storage capacity
is available, the control unit operates system 100 to maximize heat
exchange between water conduit 200 and cooling circuit 300. To this
end, the control unit executes the following steps. Control unit
102 opens first control valve 208, closes second control valve 212
in the water conduit, and actuates first pump 302 in the cooling
circuit. Opening first control valve 208 allows water from water
supply 204 to flow through primary heat exchanger 202. Actuating
first pump 302 pumps the fluid of cooling circuit 300 through
primary heat exchanger 202. Within the primary heat exchanger, the
fluid of the cooling circuit is cooled by the water of the water
conduit. The water leaving primary heat exchanger 202 flows to
holding tank 400 wherein the water is stored until the next
irrigation operation. The fluid leaving primary heat exchanger 202
is pumped through the cooling circuit, to a fan coil unit 316
operable to cool the space where the thermostat is located. Fan
coil unit 316 uses the fluid to cool air that is then circulated
though the space. The fluid leaving fan coil unit 316 is pumped
back to heat exchanger 202, thus completing a loop of the cooling
circuit.
[0040] If the temperature of the thermostat continues to rise and
exceeds a predetermined threshold temperature, 1.degree. C. above
desired temperature in the present embodiment, and control valve
208 is fully open, the control unit actuates chiller 308, which is
operable to cool the fluid in cooling circuit 300. Chiller 308 and
heat exchanger 202 then work in concert to cool the fluid in the
cooling circuit until either the temperature of the thermostat is
lowered below the threshold temperature or the temperature of the
fluid at third or fourth fluid temperature sensors 312, 318 falls
below the desired temperature. If either of these conditions is
met, control unit 102 deactuates chiller 308.
[0041] If the temperature of the fluid at fourth fluid temperature
sensor 318 falls below the temperature of water from water supply
204, heat exchanger 202 is no longer capable of cooling the fluid
and the control unit closes first control valve 208 of the water
conduit and deactuates first pump 302 of the cooling circuit.
[0042] For both sets of steps, described above, when the
temperature of the thermostat reaches the desired temperature,
cooling of the space is no longer needed and control unit 102
closes first control valve 208 and deactuates the cooling circuit
by deactuating the pumps and the chiller.
[0043] Control unit 102 also actuates the irrigation system to
perform periodic irrigation operations using water from holding
tank 400. When the above described cooling operations do not fill
holding tank 400 with sufficient water to perform a scheduled
irrigation operation, the control unit calculates the time needed
to fill holding tank 400 based on input from water level sensor 402
and operates water conduit 200 to fill the holding tank in time for
the irrigation operation. To this end, the control unit can open
second control valve 212 in bypass circuit 210 so that ground water
bypasses first heat exchanger 202 and flows directly to holding
tank 400. Control unit 102 will not actuate the irrigation system
when low level float 406 communicates to the control unit that
there is insufficient water in the holding tank.
[0044] FIG. 2 is a schematic diagram of another embodiment of the
irrigation reservoir cooling system. In this embodiment, cooling
circuit 300 comprises an optionally usable chiller circuit 328
provided with a second chiller 330 and a second chiller pump 332.
Second chiller 330 and second chiller pump 332 are connected to
cooling circuit 300 in parallel with chiller 308 and chiller pump
310. As with chiller 308, second chiller 330 is operable to reduce
the temperature of the fluid in cooling circuit 300. Second chiller
330 and second chiller pump 332 are in electronic communication
with control unit 102. In operation, the second chiller and the
second chiller pump are actuated when chiller 308 is not able to
adequately cool the fluid in cooling circuit 300. In the embodiment
of the invention shown in FIG. 2, if chiller 308 cannot provide
sufficient cooling after 20 minutes of operation, control unit 102
actuates second chiller 330 and second chiller pump 332 to provide
additional cooling. Control unit 102 deactuates the second chiller
and the second chiller pump when additional cooling is no longer
needed.
[0045] The roles of chiller 308 and second chiller 330 can be
alternated on a weekly basis to equalize their run time. For
example, every other week, second chiller 330 can be actuated first
by control unit 102, and chiller 308 actuated only to provide
supplemental cooling.
[0046] Also with reference to the embodiment shown in FIG. 2, water
conduit 200 comprises a third control valve 214 and an optionally
usable secondary branch 500 provided with a secondary heat
exchanger 502. As with primary heat exchanger 202, secondary heat
exchanger 502 is operable to exploit the low temperature of ground
water from water source 204 for cooling purposes. Secondary heat
exchanger 502 can be any device or system that is operable to
receive and exchange heat with a source of water. In the embodiment
of the invention shown in FIG. 2, the secondary heat exchanger is a
commercially available dehumidifier. Secondary branch 500 also
comprises a first control valve 504 and a first water temperature
sensor 506. The secondary branch connects to the water conduit
downstream of primary heat exchanger 202 and bypass circuit 210.
The secondary branch extends from water conduit 200 to holding tank
400. Control unit 102 is in electronic communication with secondary
heat exchanger 502, first control valve 504, and first water
temperature sensor 506.
[0047] In operation, control unit 102 functions as described above
with respect to the embodiment of the invention shown in FIG. 1 and
also determines if secondary heat exchanger 502 requires cooling
for dehumidifying air that is being pumped through heat exchanger
502. If the secondary heat exchanger requires cooling, the control
unit opens first control valve 504 of branch conduit 500 and closes
third control valve 214 of water conduit 200. In this
configuration, water that has passed through either primary heat
exchanger 202 or bypass conduit 210 will flow to secondary heat
exchanger 502. The water flows through the secondary heat exchanger
and then flows to holding tank 400.
[0048] FIG. 3 is a schematic diagram of another embodiment of the
irrigation reservoir cooling system. In this embodiment, the
irrigation reservoir cooling system additionally comprises a
snowmelt circuit 600. Generally, snowmelt circuit 600 provides
cooling to secondary branch 500 during winter months, when there is
no demand for irrigation water Snowmelt circuit 600 passes through
a tertiary heat exchanger 510 and is provided with a snowmelt pump
602, a heat exchange panel 604 and a fluid temperature sensor 606.
Heat exchange panel 604 functions as a heat sink and is positioned
outdoors, preferably in a location where unwanted snow accumulates,
such as in a driveway. Snowmelt pump 602 circulates a fluid through
the snowmelt circuit. The fluid can be any commercially available
heat transfer fluid that remains in a liquid state when exposed to
winter temperatures.
[0049] In the embodiment of the invention shown in FIG. 3,
secondary branch 500 passes through tertiary heat exchanger 510
downstream of secondary heat exchanger 502 and is provided with a
first water temperature sensor 506, a second water temperature
sensor 508, a freeze sensor 512, a second control valve 514 and an
optionally usable closed circuit branch 516. Closed circuit branch
516 is provided with a closed circuit pump 518 and a one-way check
valve 520. Control unit 102 is in electronic communication with
snowmelt pump 602, fluid temperature sensor 606, first and second
water temperature sensors 506, 508, freeze sensor 512, second
control valve 514, and closed circuit pump 518.
[0050] Control unit 102 operates the snowmelt circuit 600 when
there is no need for irrigation water and cool external
temperatures can be used to fulfill cooling needs. When these
conditions exist and secondary heat exchanger 502 signals a need
for cooling, the control unit executes the following steps. Control
valves 208, 212, 214 of the water conduit and control valves 504,
514 of the branch conduit are closed. In this configuration,
secondary branch 500 forms a closed water circuit that passes
through secondary heat exchanger 502 and tertiary heat exchanger
510. The control unit then actuates closed circuit pump 518 to pump
water through the closed circuit as follows. Water is pumped from
tertiary heat exchanger 510, wherein heat is exchanged with
snowmelt circuit 600, through one-way check valve 520 of closed
circuit branch 516, to secondary heat exchange 502, wherein the
water cools the heat exchanger. The water is then pumped back to
tertiary heat exchanger 510, completing a loop of the closed
circuit.
[0051] Control unit 102 also actuates snowmelt pump 602, which
pumps the fluid around the snowmelt circuit. The fluid is pumped
from heat exchange panel 604, wherein the fluid is cooled by the
outdoors environment, to tertiary heat exchanger 510, wherein the
cooled fluid exchanges heat with secondary branch 500. The fluid is
then pumped back to the heat exchange panel, completing a circuit
of the snowmelt circuit. In the embodiment of the invention shown
in FIG. 3, the snowmelt circuit is provided with an optionally
usable waste heat circuit 608, which further exploits the heatsink
capacity of heat exchange panel 604. The waste heat circuit directs
fluid that is flowing from heat exchange panel 604 to a boiler or
other waste heat source (not shown), and returns the fluid to
snowmelt circuit 600 upstream of the heat exchange panel.
[0052] If water in secondary branch 500 at freeze sensor 512 is in
danger of freezing, the irrigation reservoir cooling system reverts
to using water source 204 to provide cool water to secondary heat
exchanger 502. To this end, control unit 102 opens control valve
212 of water conduit 200, deactuates snowmelt pump 602 and closed
circuit pump 518, and opens first and second control valves 504,
514 of secondary branch 500.
[0053] It will be appreciated by persons skilled in the art that
the present invention is not limited by what has been particularly
shown and described hereinabove. Rather the scope of the present
invention includes both combinations and sub combinations of the
various features described hereinabove as well as variations and
modifications which would occur to persons skilled in the art upon
reading the specification and which are not in the prior art.
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