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.

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° F. to 56° 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&#39;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.
   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.   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.   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.   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™ 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° 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° 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.