NIGHT SKY COOLING SYSTEM

Abstract

A cooling system that can be used to cool water and to cool an air supply to a building. The system employs a stand alone cooling tower and a night sky cooler. As a result, the water can be cooled below the ambient wet bulb temperature.

Description

FIELD OF THE INVENTION

The present invention relates to a system for cooling water, and in particular to a system for cooling water to be used to cool the air supply to a building.

BACKGROUND

Conventional chiller units are commonly used to cool the air supply to a building. In a compression type conventional chiller, vaporized refrigerant is compressed in a compressor which causes the refrigerant to heat up. The hot gas is directed to the condenser where the refrigerant is cooled and condenses. Typically the condenser is cooled by water or air. Many such chiller systems utilize cooling towers to provide a supply of cooled water to the condenser to absorb rejected heat. The liquid refrigerant from the condenser passes through an expansion valve into the evaporator. As the fluid passes through the expansion valve, the pressure of the refrigerant is reduced causing vaporization of the liquid, which results in a large reduction in temperature. The cold refrigerant in an evaporator is used to cool a separate circulatory water system (or any other suitable fluid).

The water cooled by the chiller is then pumped to a heat exchanger that is positioned in the flow of the air supply to be cooled. The air passing over the heat exchanger is cooled and is then directed to the various spaces within the building that require cooling. The warmed water exiting the heat exchanger is redirected to the chiller to be cooled again. Conventional chiller units can quickly cool the interior of a structure, but they consume large quantities of electricity, particularly when ambient temperature and humidity are high.

Another type of conventional chiller system commonly used employs an absorptive refrigeration system. This type of system utilizes a heat source to provide the energy needed to drive the cooling system rather than being dependent on electricity to run a compressor as with the chiller system described previously. Absorptive refrigerators are popular in situations where electricity is unreliable, costly, or unavailable, where noise from the compressor is problematic, or where surplus heat is readily available. A widely used gas absorption refrigerator system cools by evaporating liquid ammonia in a hydrogen environment. The gaseous ammonia is then dissolved into water, and then later separated from the water using a source of heat. This drives off the dissolved ammonia gas which is then condensed into a liquid. The liquid ammonia then enters the hydrogen-charged evaporator to repeat the cycle. These systems are effective but are complex, expensive and require the use of potentially harmful materials.

Conventional refrigerant based cooling systems, often referred to as DX (Direct Expansion) systems, are also employed to cool the air supply to buildings. A DX system operates in a similar manner to a chiller, with the exception that the evaporator is used to cool an air stream directly (there is no chilled water loop). The condenser of a DX system is also typically air cooled. Like conventional chiller units, DX systems can quickly cool the interior of a structure, but they consume large quantities of electricity, particularly when ambient temperature and humidity are high.

In areas of the world having suitable climatic conditions evaporative cooling is employed as a viable alternative or supplement to conventional cooling systems. In particular, evaporative coolers are used as an alternative to conventional chillers or DX systems to cool the air supply to residential and commercial buildings. The use of evaporative coolers is a desirable method of cooling air because of their relatively low installation cost, their relatively lower maintenance costs, and their relatively low cost of operation in comparison with conventional chiller units and DX systems. Because evaporative coolers use the latent heat of evaporation to cool process water, such evaporative systems do have some operational limitations and disadvantages. In particular, the cooling effectiveness of an evaporative cooler is dependent on the ambient wet bulb temperature and is greatly reduced as the temperature or humidity, or both, of the ambient air increases. This means that the use of evaporative coolers is limited on days when hot and humid conditions are being experienced, and is impractical in regions experiencing prolonged periods of hot and humid weather. Evaporative cooling units are usually not able to cool a fluid to a temperature less than the wet bulb temperature of the ambient air.

Night sky cooling is another form of cooling being explored as an alternative to conventional cooling technologies. This method of cooling is predicated on the fact that the earth radiates part of the energy received from the sun during the day back to the sky at night. Space is very cold and effectively acts as a radiant black body drawing radiant energy from warmer objects such as the earth. The effective temperature of the night sky is typically around 10 to 15 degrees cooler than the air temperature at the earth's surface, giving an effective temperature at times as low as −15° C.

The effective sky temperature encountered on any given night is dependant on a number of factors including air temperature, cloud cover and the moisture content of the air. When the sky is cloudy or when there is a relatively large amount of water vapour in the air, the effective sky temperature will be warmer. However, particularly on clear dry nights the effective sky temperature can be very low, drawing very large amounts of heat from the earth through this radiant exchange.

Night sky cooling is a technology that takes advantage of the cooling effect of the night sky to produce cooled water for building cooling applications. The first night sky cooling systems simply comprised open bodies of water on the roof of a building that were exposed to the night sky. The stored coolness in the water was used as a passive barrier to solar heat. Subsequent designs have used roof ponds covered by floating insulation with water sprays used to expose an upper layer of water to the night sky and other designs consist of water sprays on the roof of a building used to expose water to the night sky. The water is then collected and is stored in a large tank ready to be used to cool the building over subsequent days. The spray system is turned on at night. Existing night sky cooling systems generally use the cooled water as a pre-cooler to conventional air conditioning or as a way to handle only base air conditioning loads.

It would advantageous to couple to the beneficial cooling properties of an evaporative cooling system and a night sky cooling system to create a system that can be used alone, or in an assistive manner with a conventional chiller, or with a DX system, that mitigates some of the limitations of existing evaporative systems. It would also be preferable if the new evaporative cooling system had a greater cooling capacity than existing evaporative cooling systems.

SUMMARY OF THE INVENTION

An interconnected system for cooling the air supply to a building, the system comprising;

• • (a) a heat exchange element;
  • (b) means for forcing the air supply over the heat exchange element;
  • (c) a pump for circulating water through the system;
  • (d) a cooling tower connected in series with a night sky cooler, the cooling tower being upstream of the night sky cooler; and
  • (e) storage means in fluid communication with the cooling tower, night sky cooler and heat exchange element, for storing cooled water and for storing warm water.

In one embodiment the system is interconnected by conduits having valve means for diverting the flow of water between components of the system. In one embodiment, one of the conduits comprises a bypass conduit having valve means which may be configured such that water selectively flows directly from the cooling tower to the night sky cooler; or from the cooling tower to the storage means for storing cooled water bypassing the night sky cooler.

In one embodiment the system has conduits having valve means which may be configured such that water selectively flows directly from the cooling tower to the heat exchange element, and from the heat exchange element to the cooling tower. In one embodiment the storage means consists of a storage tank for storing cooled water and a storage tank for storing warmed water.

In one embodiment the means for selectively forcing the air supply over the first heat exchange element is a duct, at least one bypass louver and a fan. In one embodiment the system has a second heat exchange element in series with the first heat exchange element, the second heat exchange element also being interconnected to the system by conduits having valve means.

In one embodiment the system has means for activating and deactivating all, or any of, the cooling tower, the pump means and the valve means. In one embodiment, the activation and deactivation means is automated and is responsive to any one, or any combination of; changes in cooling requirements; ambient air temperature; the amount of water contained in the storage means; the temperature of the water contained in the storage means; and changes in cooling requirements and ambient air temperature.

In one embodiment the heat exchange element comprises finned cooling coils. In one embodiment there is a single stratified storage tank that is used to hold both warmed and cooled water. In one embodiment, there is an additional heat exchange element proximate to the first heat exchange element, the additional heat exchange element being connected to a conventional chiller. In one embodiment there the additional heat exchange element is the evaporator of a DX system.

In one embodiment there is a second evaporative system having a cooling tower, a pump and a heat exchange element, wherein the heat exchange element of the second evaporative system is used to pre-cool the air supply to the first cooling tower. In one embodiment there is a third evaporative system having a cooling tower, a pump and a heat exchange element, wherein the heat exchange element of the third evaporative system is used to pre-cool the air supply to the cooling tower of the second evaporative cooling system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of an exemplary embodiment with reference to the accompanying simplified, diagrammatic, not-to-scale drawings. In the drawings:

FIG. 1 is a diagrammatic depiction of the prior art.

FIG. 2 is a diagrammatic depiction of one system of the present invention having a single cooling tower and a night sky cooler that provide cooled water to a storage tank.

FIG. 3 is a diagrammatic depiction of one system of the present invention having a single cooling tower and a night sky cooler.

FIG. 4 is a diagrammatic depiction of one system of the present invention having a cooling tower and a night sky cooler and having a second evaporative cooling system.

FIG. 4A is a detailed diagrammatic depiction of a cooling tower having a second dedicated evaporative cooling system.

FIG. 5 is a diagrammatic depiction of one embodiment of the present invention having a cooling tower and a night sky cooler and having a second evaporative cooling system.

FIG. 6 is a diagrammatic depiction of one embodiment of the present invention having a cooling tower and a night sky cooler and having second and third evaporative cooling systems.

FIG. 6A is a detailed diagrammatic depiction of a cooling tower having second and third dedicated evaporative cooling systems.

FIG. 7 is a diagrammatic depiction of one embodiment of the present invention having a cooling tower and a night sky cooler and having second and third evaporative cooling systems.

FIG. 8 is a diagrammatic depiction of one embodiment of the present invention having a single cooling tower and a night sky cooler and two heat exchange elements.

FIG. 9 is a diagrammatic depiction of one embodiment of the present invention having a single cooling tower and a night sky cooler and two heat exchange elements.

FIG. 10 is a diagrammatic depiction of one embodiment of the present invention having a cooling tower and a night sky cooler and two heat exchange elements and having a second evaporative cooling system.

FIG. 11 is a diagrammatic depiction of one embodiment of the present invention having a cooling tower and a night sky cooler and two heat exchange elements and having a second evaporative cooling system.

FIG. 12 is a diagrammatic depiction of one embodiment of the present invention having a cooling tower and a night sky cooler and two heat exchange elements, and having second and third evaporative cooling systems.

FIG. 13 is a diagrammatic depiction of one embodiment of the present invention having a cooling tower and a night sky cooler and two heat exchange elements, and having second and third evaporative cooling systems.

FIG. 14 is diagrammatic depiction of a cross-flow cooling tower.

FIG. 15 is diagrammatic depiction of a counter-flow cooling tower.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides for a system for cooling water and in particular to a system for cooling an air supply to a residential or commercial building using such cooled water. When describing the present invention, all terms not defined herein have their common art-recognized meanings. To the extent that the following description is of a specific embodiment or a particular use of the invention, it is intended to be illustrative only, and not limiting of the claimed invention. The following description is intended to cover all alternatives, modifications and equivalents that are included in the spirit and scope of the invention, as defined in the appended claims. In this patent the following words are intended to have the following meaning:

“Building” shall mean any structure, commercial or residential in nature, forming an open, partially enclosed, or enclosed space constructed by a planned process of combining materials and components to meet specific conditions of use.

“Conventional chiller” means any chiller unit commonly used with HVAC systems implementing vapor compression of a refrigerant (typically having a compressor, a condenser and an evaporator) or implementing an absorptive refrigeration system.

“Cooling tower” means a tower or other structure that incorporates an evaporative cooler, an evaporative cooler being a cooler that lowers the temperature of a water stream by exposing the water to unsaturated air, promoting evaporation. Evaporation consumes energy from the water stream, reducing the temperature of the water. This cooled water can be used directly (open circuit) or passed over an internal heat exchanger to cool a separate fluid stream (closed circuit). The term cooling tower as used herein is intended to include both cross flow and counter flow type cooling towers. In a cross flow design, the air flow is directed substantially perpendicular to the water flow. In contrast, in a counter flow design, the air flow is substantially opposite of the water flow. The term cooling tower as used herein also encompasses cooling towers having air flow generated by natural draft and mechanical draft including without limitation, induced draft, forced draft and fan assisted natural draft.

“DX system” means an air conditioning unit typically used in residential and smaller commercial buildings implementing vapor compression of a refrigerant, typically having a compressor, a condenser and an evaporator in direct contact with the air supply that requires cooling.

“Night sky cooler” means a structure that is designed to cool water by night sky cooling by radiating the heat of the water to the night sky.

“Wet bulb temperature” means the temperature measured by a thermometer whose bulb is covered by a muslin sleeve which is kept moist with distilled and clean water, freely exposed to the air and free from radiation. At relative humidities below 100%, water evaporates from the bulb which cools the bulb below ambient temperature. To determine relative humidity, ambient temperature is measured using an ordinary thermometer, known as a dry-bulb thermometer. At any given ambient temperature, less relative humidity results in a greater difference between the dry-bulb and wet-bulb temperatures; the wet bulb is colder. The precise relative humidity is determined by finding a wet-bulb and dry-bulb temperatures on a psychrometric chart. The wet bulb temperature is dependant on the dry bulb temperature and the relative humidity. A decrease in dry bulb temperature (with the humidity ratio constant) will also decrease the wet bulb temperature, but not by the same magnitude.

The present invention is directed to a system for cooling water and in particular to a system for cooling an air supply to a residential or commercial building using such cooled water. FIG. 1 depicts a prior art evaporative cooling system (11). The system (11) is comprised of a cooling tower (12) connected to heat exchange element (14). The purpose of the cooling tower (12) is to provide a source of cooled water to the heat exchange element (14). A pump (18) moves water through the system. The heat exchange element (14) is disposed in the flow of the primary air supply (16). A fan (20) draws the air supply. When conditions in the building and external environment are such that the air supply does not require cooling, the cooling tower (20) and pump (18) are inoperative. If the need for cooling arises, the cooling tower (12) is activated and cooled fluid is circulated through the evaporative cooling system (11) to the heat exchange element (12) and then back to the cooling tower (12). The air-flow (A) passes over the heat exchange element (14) and is cooled. If the cooling tower (12) and associated heat exchange element (14) cannot cool the air sufficiently, then a conventional chiller or DX system (13) having heat exchange element (15) may be activated to cool the air supply (16) provided that as cooling requirements are reduced, the conventional chiller or DX system, as the case may be, can be deactivated. On days where the wet bulb temperature exceeds a desired level, the efficiency of the cooling tower (12) may be so impaired that the conventional chiller or DX system is run alone to cool the primary air supply. These prior art evaporative cooling systems are limited to the capability of the cooling tower (12) to supply cool water to the heat exchange element (14). On certain days, especially when there is high ambient humidity, the wet bulb temperature rises, greatly reducing the ability of the stand alone cooling tower to supply water cold enough to sufficiently cool the air supply. In such circumstances, the conventional chiller or DX system must be relied upon heavily which is costly due to the consumption of large amounts of energy.

Night sky cooling systems have been developed to harness the cooling properties of the night sky. Night sky cooling is a technology that takes advantage of the radiative heat exchange of the night sky to produce cooled water for building cooling applications. Night sky cooling systems originated as simplistic open bodies of water on the roof of a building that could be exposed to the night sky if conditions were appropriate. The water cooled by night sky cooling was used in the daytime as a passive barrier to solar heat. Subsequent designs were more elaborate in design. For example, a common current design employs roof ponds covered by floating insulation with water sprays used to expose an upper layer of water to the night sky. Other designs incorporate water sprays on the roof of a building used to expose a thin film of water to the night sky. Both such systems achieve some cooling through passive evaporation to the atmosphere. However, evaporative cooling facilitated by such spray systems and open bodies of water does not match the efficiency of a dedicated cooling tower. Existing night sky cooling systems generally use the cooled water as a pre-cooler to conventional air conditioning, or as a way to handle only base air conditioning loads.

The present invention combines both a night sky cooler and a separate cooling tower in the same system. In this manner, the evaporative cooling aspect of the system is separated from the night sky cooling aspect of the system and is conducted in the cooling tower. Consequently, if conditions are favourable, water may be cooled to, or below, the wet bulb temperature through evaporative cooling in a cooling tower, and then the water may be further cooled using the night sky cooler. The resultant cooled water can be stored in a receptacle for use during the warmer day time period. The systems of the present invention combine the beneficial properties of a night sky cooler and a cooling tower.

The systems of the present invention are able to provide a steady supply of cold water to a heat exchange element, even on more humid days in comparison to prior art evaporative cooling systems relying on a cooling tower alone. As a result, the required use of an associated conventional chiller or DX system may be eliminated or reduced and a corresponding reduction in electricity consumption to cool the air supply (16) is possible.

FIG. 2 depicts one embodiment of a cooling system (10) of the present invention. The system (10) has pump means for circulating fluid (18) which may comprise one or more suitable pumps as may be selected by one skilled in the art including, without limitation, centrifugal pumps. The system (10) has a first heat exchange element (14) positioned in the air supply flow (16). The first heat exchange element (14) of the system (10) and all heat exchange elements described herein, may comprise any suitable heat exchanger having an arrangement of finned coils and may be constructed from any suitable metals including, without limitation, copper and aluminum. The air supply (16) to be cooled by the system (10) may be entirely external fresh air, entirely return or exhaust air, or of a mixture of both. Such mixtures are achieved using louvers (23) that divert or allow the relevant air flow. The means for forcing the air supply (16) over the first heat exchange element (14) is a combination of a fan (20), a duct (21) and at least one bypass louver (17). In one embodiment, the fan (20) has modulated speeds to accommodate varying cooling requirements and to vary the force of the flow of the air supply. The bypass louver (17) may be opened and shut to divert air the air supply (16) across the first heat exchange element (14) within the duct (21). The system (10) has a cooling tower (12) a night sky cooler (24).

The system has means for the storage of cooled and warmed water. FIG. 2 depicts an embodiment wherein the storage means comprises two storage tanks (28,30), however, as will be described later, in one embodiment a single stratified storage tank may be used. As can be seen in FIG. 2, the components of the system (10) are interconnected by conduits (19) which may constructed from any suitable piping as is employed in the art. Suitable piping includes, without limitation, plastic piping, galvanized metal piping, and stainless steel piping. The gauge and thickness of the piping will vary depending on the pressure requirements and load capacity of the particular system. The conduits have associated valve means (26) which may be opened and closed to divert the flow of the water between the interconnected components of the system (10) as will described in more detail below. The valve means may comprise any suitable valve employed by those skilled in the art to permit, or prevent, the flow of fluid through a conduit. Examples of suitable valves include, but are not limited to gate valves, butterfly valves and ball valves.

If conditions are suitable for night cooling, the cooling tower (12) is activated at night and it cools the circulating water by evaporative cooling. Water cooled by the cooling tower (12) gathers in a reservoir at the base of the cooling tower (12) and then flows through a conduit to the night sky cooler (24). The water is further cooled in the night sky cooler (24) through radiative heat exchange with the night sky. Water from the night sky cooler (24) is then diverted to one of the storage tanks (28, 30) to be stored for use during the daytime hours. If conditions are not suitable for night sky cooling, valves in the conduits between the cooling tower (12) and the night sky cooler (24) can be closed and the cooling tower (12) may be still operated with the cooled water from the cooling tower (12) bypassing the night sky cooler through a bypass conduit (40) and passing directly to the storage tank being used to hold the cooled fluid. If cooling of the air supply (16) is needed during the day, or during the night, cooled water from the storage tank receiving and holding the cooled water is directed to the first heat exchange element (14). Bypass louver (17) is closed and the air supply (16) is cooled. Warmed water from the first heat exchange element (14) is diverted to the storage tank being used to hold warmed water by opening and closing the appropriate valves (26) in the conduits (19). The warmed water is stored until night at which time the appropriate valves are opened allowing the warmed water to flow to the cooling tower (12) through the conduits (19) for cooling in the manner described above. At night, the warmed water from the heat exchange element (14) may diverted directly to the cooling tower (12) for cooling by opening and closing the appropriate valves (26) in the conduits (19).

The night sky cooler (24) used in any of the embodiments described herein may consist of any suitable equipment that facilitates the radiation of heat from the water to the night sky. A system that directly exposes a film or expansive body of water to the night sky is suitable. However, a night sky cooler comprising a modified solar panel having a modified coating designed to radiate heat with the water passing through the interior of the panel is preferable.

The systems of the present invention may be used in an assistive manner in conjunction with a conventional chiller or a DX System. FIG. 2 depicts a conventional chiller (13) having a heat exchange element (15) disposed in the duct (21) adjacent to the first heat exchange element (14). A bypass louver (17) associated with the conventional chiller heat exchange element (15) may be opened and closed as required to divert air flow across the heat exchange element (15). An associated DX system or conventional chiller would preferably only be activated and used when the system (10) is unable to sufficiently cool the air supply (16). In certain geographical locations where ambient conditions are suitable, it is possible to install a system of the present invention without an associated conventional chiller or DX system. While geographic location of the subject building and the associated ambient conditions greatly influence the cooling capability of the systems of the present invention, it can also be understood that the required amount of cooling of an incoming air supply will also be influenced subjectively by the demands of the occupants of the building that is receiving the air supply.

As shown in FIG. 3, in one embodiment, instead of the storage tanks being the only source of cooled water for the heat exchange element (14), the conduits (19) and valves (26) may be configured such that by closing the appropriate valves and by employing the bypass conduit (40), the cooling tower (12) and the first heat exchange element (14) form a continuous loop. With the creation of such a loop, the cooling tower (12) feeds cooled water directly to the heat exchange element (14), bypassing the night sky cooler (24) through the bypass conduit (40) and bypassing and the storage tanks (28, 30), with the heat exchange element (14) feeding warmed water directly back to the to the cooling tower (12) through the conduits (19).

Operation in this manner would allow use of the cooling tower (12) to provide cooled water to the first heat exchange element (14) at times when night sky cooling cannot occur such as during the day or on cloudy nights. It also permits flexibility to reserve the use of previously cooled water being held in the storage tank until such time as the cooling tower (12) is unable to provide a sufficient supply of cooled water to the heat exchange element (14). For example, water can be cooled at night using the night sky cooler (24) and the cooling tower (12) and can be stored in a storage tank. During the following day, the valves are coordinated such that the cooling tower can be run alone to provide cooled water directly to the heat exchange element (14), provided that when the cooling tower (12) can no longer meet load requirements, the cooling tower (12) would be deactivated and the cooled water from the storage tank would be used to supply the heat exchange element by opening and closing the appropriate valves. The warmed water is returned to the other storage tank to be held until nightfall when the cooling cycle can start over again.

The embodiments described and depicted herein show the use of two storage tanks (28, 30) that are used to synchronously store cooled water and heated water. The valve means (26) permits one tank to receive and store cooled water at night and to then provide cooled water to the heat exchange element (14) during the day. The other tank receives warmed water from the heat exchange element (14), stores the warmed water and feeds warmed water to the cooling tower (12) and night sky cooler (24) for cooling at night. However, the storage means may comprise a single storage tank employing stratified storage means as are commonly employed by those skilled in the art may also be used with the systems of the present invention.

The cooling towers (12) used in the system described herein, can be any suitable cooling tower as would be selected by one skilled in the art. It has been determined that the Baltimore Air Coil Series 3000 (VSD) 3473A-KM/Q with a 10 horse power fan is suitable, such suggestion not intended to be limiting of the invention claimed herein. Both cross-flow type cooling towers and counter-flow type cooling towers may be used with the systems of the present invention.

FIG. 14 depicts a cross-flow cooling tower (80). Cross-flow is a design in which the air flow (AF) is directed perpendicular to the water flow (WF). Air flow (AF) enters one or more vertical faces of the cooling tower (80) to meet the fill material (82). Water flows (perpendicular to the air) through the fill material (82) by gravity. The air passes through the fill material (82) and thus past the water flow (WF) into an open plenum area. A distribution or hot water basin (84) consisting of a deep pan with holes or nozzles (not shown) in the bottom is utilized in a cross-flow tower. Gravity distributes the water through the nozzles uniformly across the fill material (82).

FIG. 15 depicts a counter-flow cooling tower (90). In a counter-flow design the air flow (AF) is substantially opposite of the water flow (WF). The air flow (AF) first enters an open area beneath the fill media (92) and is then drawn up vertically. The water is sprayed through pressurized nozzles (94) and flows downward through the fill (92), opposite to the air flow (AF).

In both cross-flow and counter-flow cooling towers the interaction of the air and water flow allow a partial equalization and evaporation of water and the air supply, now saturated with water vapor (DA), is discharged from the cooling tower. Further, in each type of cooling tower a sump or cold water basin (86) is used to contain the cooled water after its interaction with the air flow. Both cross-flow and counter-flow designs can be used in natural draft and mechanical draft, and hybrid draft cooling towers.

It will be understood by one skilled in the art, that in accordance with standard practice, the evaporative cooling systems will be connected to a water source to replenish the volume of water lost through evaporation in the cooling tower. The water source may include without limitation, treated water or rain water, or a mixture of both. It will also be understood by one skilled in the art that some form of water treatment system and filtration system will be employed with the evaporative cooling systems to maintain the water quality and to minimize corrosive damage. The water in the system may also be treated with various suitable chemicals and compounds to enhance its evaporative qualities.

The cooling systems described herein, including the individual components of each such system such as pumps, cooling towers, valves and night sky coolers may be controlled by automated activation and deactivation means that is responsive to cooling demands and system output and to ambient temperatures. In general terms, any suitable electronic sensory feed-back system may be utilized as would be selected by one skilled in the art. Such activation and deactivation means may be controlled by a central computer processor that is adapted to receive and interpret sensory data regarding system output, cooling demands and ambient conditions. The sensory system may also be programmed to monitor the volume and temperature of the water in the storage tanks, and to input and process data regarding the same.

As shown in FIG. 4, in one embodiment, the system (10) relies on air circulation through the cooling tower (12) in combination with a pre-cooling evaporative process. The system (10) thus comprises a second evaporative cooling system (60). As shown in more detail in FIG. 4A, the second evaporative system has a pump for circulating fluid (64), a second cooling tower (62) and a heat exchange element (66). The apparatus has means for selectively forcing the air supply to the primary cooling tower (B) over the heat exchange element (66) of the second evaporative cooling system (60). Such means may be a combination of a duct (not shown), a fan (63) and bypass louvers (52). In one embodiment, the fan (63) is an integral part of the cooling tower (12). The second evaporative cooling system is designed to cool the air supply (B) to the primary cooling tower (12). When the bypass louvers (52) are open, the air-flow (B) bypasses the second heat exchange element (66). When the bypass louvers (52) are closed, the air-flow (B) passes through the second heat exchange element (66). It can be understood that when the bypass louvers (52) are closed, and when the second cooling tower (62) is activated, the second heat exchange element (66) will pre-cool the air supply (B) to cooling tower (12). As a result, the wet bulb temperature of the primary cooling tower (12) will be reduced, enhancing the cooling capacity of the primary cooling tower (12). In the embodiment depicted in FIG. 4, the cooled water from the cooling tower (12) and the night sky cooler (24), or from the cooling tower (12) alone, is diverted to one of the storage tanks, which then supplies the cooled water to the heat exchange element (14) on demand.

FIG. 5 depicts an embodiment in which there is a second evaporative cooling system (60) to pre-cool the air supply to the primary cooling tower (12), but in which the conduits (19) and valves (26) may be configured such that by closing the appropriate valves, the primary cooling tower (12) and the first heat exchange element (14) form a continuous loop. With the creation of such a loop, the primary cooling tower (12) feeds cooled water directly to the heat exchange element (14), bypassing the night sky cooler (24) and the storage tanks (28,30), with the heat exchange element (14) feeding warmed water directly back to the to the cooling tower (12) through the conduits (19). The advantages of such a configuration having been previously discussed.

As shown in FIGS. 6 and 7, a third evaporative cooling system (70) may be added to the systems of the present invention. As shown in more detail in FIG. 6A, the third evaporative cooling system (70) has a third cooling tower (72) and a third fluid pump (74) and a third heat exchange element (76) may also be added in a like manner to the apparatus (10) to cool the air supply (C) to the second cooling tower (62). Furthermore, it can be understood that fourth and maybe fifth evaporative cooling systems may also be added with each such additional system being designed to cool the air supply to the cooling tower of the preceding evaporative cooling system. It can be understood that if a plurality of such staged evaporative cooling systems are used, they may be activated sequentially as the cooling demands are increased.

As shown in FIG. 8, a system may be employed to cool air such that there are more than one heat exchange elements positioned in the air-flow (16). FIG. 8 shows a second heat exchange element (33) adjacent to a first heat exchange element (14). In the system shown in FIG. 8, the cooling tower (12) and night sky cooler (24) feed cooled water to the storage tanks (28,30) which in turn supply cooled water to the heat exchange elements (14, 33) as required. It can be understood that if more than one heat exchange element is employed, the heat exchange elements may be employed selectively and sequentially to meet varying cooling demands and in response to varying ambient conditions. As more heat exchange elements are employed in the flow path of the air (16), it may be necessary to increase fan speed, to utilize a larger fan, or to use more fans to physically force the air through the heat exchange elements. FIG. 9 depicts one embodiment with a single cooling tower (12) and a night sky cooler (24) wherein the valves (26) of the system may be coordinated such that by closing the appropriate valves, the primary cooling tower (12) and the first heat exchange element (14) form a continuous loop.

It also possible to use more than heat exchange element to cool the air supply (16) in conjunction with systems having a second evaporative cooling system as shown in FIGS. 10 and 11, and having a third evaporative cooling system as shown in FIGS. 12 and 13.

While the embodiments described above, are directed to cooling air, it can be understood that the heat exchange elements of the systems described herein may be used to cool any gaseous or liquid substance that needs cooling. Thus, the present invention would have equal application in industrial processes requiring the cooling of a process air supply or requiring the cooling of some process substance.

EXAMPLES

Examples will now be provided of possible operation sequences and methodologies for certain embodiments of the present invention. Such examples are only suggested operation sequences and are not intended to be limiting of the systems, or of the methods of operating the systems described and claimed herein.

Example 1

Operation of the system as depicted in FIG. 3 having a single cooling tower (12), a night sky cooler (24), two storage tanks (28,30) and a single heat exchange element (14).

The sequence of operation at night for night time cooling and storage is as follows. Assuming that the first tank (30) is full of spent (warn) water, the cooling tower (12) is activated and valve V4 is opened to allow the flow of water from tank (30) to pump P2. Pump P2 is started and valve V3 is opened to allow the flow of water to the cooling tower (12) where water is cooled. Valve V1 is closed to allow the flow of water from the cooling tower (12) to the night sky cooler (24). Further cooling is achieved in the night sky cooler (24) by means of heat radiation to space. Valve V2 is opened to allow night sky cooler (24) discharge to flow to pump P1. Valve V7 is opened to allow flow to valve V5 and to the second tank (28), being the empty tank in this case which will be used to store the cooled water for later use. Operation in this manner continues until the second tank (28) is full.

The sequence for daytime operation is as follows. Valve V1 is opened to allow flow from the cooling tower (12) to valve V2, bypassing night sky cooler (24). Valve V2 is opened to allow the flow of water to pump P1. Pump P1 is started with valve V7 open and with valve V6 opened to allow the flow of water to the heat exchange element (14). Discharge from the heat exchange element (14) flows to valve V8 which is open allowing flow back to the cooling tower (12). When the air supply (16) temperature leaving the heat exchange element (14) exceeds a set point indicating that the cooling tower (12) is no longer able to sufficiently cool the air supply (16) alone, then the cooling tower (12) is deactivated and the cooled water from the storage tank (28) is called upon. Valve V4 is opened from the full second tank (28) allowing flow to pump P2. Pump P2 is started and valve V3 is opened with valve V6 also being open to allow flow to the heat exchange element (14). The discharged warm water from the heat exchange element (14) flows through open valves V8, V7 and V5 to the first tank (30). This process is continued until either operational schedule ends or until the contents of the second tank (28) are depleted.

Example 2

Operation of the system as depicted in FIG. 5 having a cooling tower (12), a night sky cooler (24), two storage tanks (28,30) and a single heat exchange element (14) and a second evaporative cooling system (60).

The sequence of operation for night cooling and storage is as follows. Assuming that the first tank (30) is full of spent (warm) water, the cooling tower (12) is activated and valve V4 is opened to allow the flow of water from the first tank (30) to pump P2. Pump P2 and pump P3 are started and valve V3 is opened to allow the flow of water to the primary cooling tower (12) where water is cooled. The air supply to the primary cooling tower (12) is pre-cooled by the second evaporative cooling system (60). Discharge from the cooling tower (12) flows to valve V1 which is closed to allow flow to the night sky cooler (24) and further cooling of the water is achieved through heat radiation to space. Valve V2 is opened to allow discharge from the night sky cooler (24) to flow to pump P1 with valve V7 being opened to allow flow to valve V5 that is opened to allow flow into the second tank (28), being the tank that will store the cooled water until required later use. Operation continues in this manner until the second tank (28) is full.

The daytime sequence is as follows. The cooling tower (12) is activated. Valve V1 is opened to allow flow from the cooling tower (12) to valve V2 bypassing night sky cooler (24). Valve V2 is opened to allow the flow of water to pump P1. Pump P1 is started with valve V7 being opened to valve V6 which is also opened allowing the flow of water to the heat exchange element (14). Discharged warm water from the heat exchange element (14) flows to valve V8 which is open allowing flow back to the cooling tower (12). Upon the air temperature leaving the heat exchange element (14) exceeding a set point, pump P3 and the cooling tower (62) of the second evaporative system (60) are activated to pre-cool the air supply to the primary cooling tower (120 thereby lowering the discharge temperature of the cooling tower (12). When the temperature set point cannot be maintained using the cooling tower (12) and the second evaporative cooling system (60), stored water operation begins. The cooling towers (12, 62) and pumps P1 and P3 are deactivated. Valve V4 is opened allowing flow from the second tank (28) that is full of cool water to pump P2. Pump P2 is started and valve V3 is opened, as is valve V6 allowing flow to the heat exchange element (14). The heat exchange element (14) discharges warm water to valve V8 that is closed directing the flow to valve V7 that is open. The flow moves form valve V7 to valve V5 that is opened allowing flow into the first tank (30). This process is continued until either operational schedule ends of until contents of the second tank (28) are depleted.

Example 3

Operation of the system as depicted in FIG. 7 having a cooling tower (12), a night sky cooler (24), two storage tanks (28,30) and a single heat exchange element (14) and a second (60) and third (70) evaporative cooling system.

The sequence of operation for night cooling and storage is as follows. Assuming that the first tank (30) is full of spent (warm) water, then the cooling tower (12) is activated and valve V4 is opened to allow flow from the first tank (30) to pump P2. Pump P2 is started and valve V3 is opened to allow the flow of water to the primary cooling tower (12) where water is cooled. Discharge from the cooling tower (12) flows to valve V1 which is closed to allow the flow of water to the night sky cooler (24) where further cooling is achieved by radiation to space. Valve V2 is opened to allow the flow of water from the night sky cooler (24) to pump P1. Pump P1 is activated with valve V7 opened to direct flow to valve V5. Valve V5 is opened to allow flow into the second tank (28), which stores the cooled water until needed later. Operation in this manner continues until the second tank (28) is full.

The daytime sequence is as follows. The cooling tower (12) is activated and valve V1 is opened to allow flow from cooling tower (12) to valve V2 bypassing the night sky cooler (24). Valve V2 is opened to allow the flow of water to pump P1. Pump P1 is started and valve V7 is opened directing the flow to valve V6 which is also open allowing flow to the heat exchange element (14). Discharged warm water from the heat exchange element (14) flows to valve V8 which is open allowing the warmed water to flow back to the cooling tower (12). When the air temperature of the air supply (16) discharged from the heat exchange element (14) exceeds a set point, pump P3 and the cooling tower (62) of the second evaporative cooling system (60) are activated to pre-cool the air supply to the primary cooling tower (12) to lower the water discharge temperature of the cooling tower (12). If the set point temperature is exceeded again, pump P4 and the cooling tower (72) of the third evaporative cooling system (70) are activated to pre-cool the air supply to the cooling tower (62) of the second evaporative system (60). If the set point temperature still cannot be maintained then the cooling towers are deactivated, and the use of the stored cooled water in the heat exchange element (14) begins. Valve V4 is opened to allow the flow of water from the second tank (28) to pump P2. Pump P2 is activated and valve V3 is opened allowing flow to valve V6 which is also opened to allow flow to the heat exchange element (14). The warm water from the heat exchange element (14) is discharged to valve V8 which is opened allowing flow to valve V7. Valve v7 directs the flow to valve V5 which is open allowing flow into the first storage tank (30). This process is continued until either operational schedule ends or until the contents of the second tank (28) are depleted.

Example 4

Operation of the system as depicted in FIG. 9 having a cooling tower (12), a night sky cooler (24), two storage tanks (28,30) and a first heat exchange element (14), and a second heat exchange element (33)

The sequence of operation for night cooling and storage is as follows. Assuming that the first tank (30) is full of spent (warm) water, then the cooling tower (12) is activated and valve V4 is opened to allow flow from the first tank (30) to pump P1. Pump P1 is started and valve V3 is opened to allow the flow of water to the cooling tower (12) where the water is cooled. Discharge from the cooling tower (12) flows to valve V1 that is closed to direct the flow of water to the night sky cooler (24) where further cooling is achieved through heat radiation to space. Valve V2 is opened to allow the water discharged by the night sky cooler (24) to flow to pump P2. Pump P2 is activated with valve V9 opened to allow flow to valve V7, also opened to allow flow into the second tank (28) that is used to store the cooled water. Operation continues until the second tank (28) is full.

The daytime sequence is as follows. The cooling tower (12) is activated and valve V1 is opened to allow the flow of water from cooling tower (12) to valve V2 bypassing the night sky cooler (24). Valve V2 is opened to allow the flow of water to pump P1. Pump P1 is started and valve V9 is opened allow the flow of water to the first heat exchange element (14). Warm water discharged from the first heat exchange element (14) flows directly back to the cooling tower (12). Upon the air temperature of the air supply (16) being discharged by the first heat exchange element (14) exceeding a set point temperature, stored water operation begins. Valve V4 is opened and water from the second tank (28) flows to pump P1. Pump P1 is started and valve V3 is closed so that water flows to valve V6. Valve V6 is open allowing the flow of the water to the second heat exchange element (33). Warmed water from the second heat exchange element (33) is discharged to valve V8 that is opened directing flow to V7. Valve V7 is open directing flow to valve V5 that is open allowing flow in the first tank (30). This process is continued until either operational schedule ends or until the contents of the second tank (28) are depleted.

As will be apparent to those skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the scope of the invention claimed herein.

Claims

1. An interconnected system for cooling the air supply to a building, the system comprising;

(a) a heat exchange element;

(b) means for forcing the air supply over the heat exchange element;

(c) a pump for circulating water through the system;

(d) a cooling tower connected in series with a night sky cooler, the cooling tower being upstream of the night sky cooler; and

(e) storage means in fluid communication with the cooling tower, night sky cooler and heat exchange element, for storing cooled water and for storing warm water.

2. The system of claim 1 wherein the system is interconnected by conduits having valve means for diverting the flow of water between components of the system.

3. The system of claim 2 wherein one of the conduits comprises a bypass conduit having valve means which may be configured such that water selectively flows directly from:

(a) the cooling tower to the night sky cooler; or

(b) the cooling tower to the storage means for storing cooled water bypassing the night sky cooler.

4. The system of claim 3 further comprising conduits having valve means which may be configured such that water selectively flows directly from:

(a) the cooling tower to the heat exchange element; and

(b) the heat exchange element to the cooling tower.

5. The system of claim 1 wherein the storage means comprises at least one storage tank for storing cooled water and at least one storage tank for storing warmed water.

6. The system of claim 1 wherein the means for selectively forcing the air supply over the first heat exchange element comprises a duct, at least one bypass louver and a fan.

7. The system of claim 1 further comprising a second heat exchange element in series with the first heat exchange element, the second heat exchange element being interconnected to the system by conduits having valve means.

8. The system of claim 1 further comprising control means for activating and deactivating all, or any of, the cooling tower, the pump means and the valve means.

9. The system of claim 8 wherein the control means is automated and is responsive to any one, or any combination of, the following:

(a) changes in cooling requirements;

(b) ambient air temperature;

(c) the amount of water contained in the storage means;

(d) the temperature of the water contained in the storage means; and

(e) changes in cooling requirements and ambient air temperature.

10. The system of claim 1 wherein the heat exchange element comprises finned cooling coils.

11. The system of claim 1 wherein the storage means comprises single stratified storage tank that is able to store both warmed and cooled water.

12. The system of claim 1 further comprising an additional heat exchange element proximate to the first heat exchange element, the additional heat exchange element being connected to a conventional chiller.

13. The system of claim 1 further comprising an additional heat exchange element proximate to the first heat exchange element, the additional heat exchange element comprising the evaporator of a DX system.

14. The system of claim 1 further comprising second evaporative system having a cooling tower, a pump and a heat exchange element, wherein the heat exchange element of the second evaporative system may be used to pre-cool the air supply to the cooling tower of the system of claim 1.

15. The system of claim 14 further comprising a second heat exchange element in series with the first heat exchange element, the second heat exchange element being interconnected to the system by conduits having valve means.

16. The system of claim 14 further comprising a third evaporative system having a cooling tower, a pump and a heat exchange element, wherein the heat exchange element of the third evaporative system may be used to pre-cool the air supply to the cooling tower of the second evaporative cooling system.

17. The system of claim 16 further comprising a second heat exchange element in series with the first heat exchange element, the second heat exchange element being interconnected to the system by conduits having valve means.