US20080041083A1

US20080041083A1 - Low-cost air conditioning system for open area

Info

Publication number: US20080041083A1
Application number: US11/504,083
Authority: US
Inventors: Ahmed Z. Al-Garni; Ayman H. Kassem; Abdullah M. Al-Garni; Farooq Saeed
Original assignee: King Fahd University of Petroleum and Minerals
Current assignee: King Fahd University of Petroleum and Minerals
Priority date: 2006-08-15
Filing date: 2006-08-15
Publication date: 2008-02-21

Abstract

The solar-powered air conditioning system is a low cost, environmentally friendly system for cooling air through evaporative cooling. The system includes a motor-driven fan for producing a directed air stream. A water delivery system is in communication with an external water supply and produces water droplets, which are delivered into the directed air stream. Evaporation of the water droplets within the directed air stream lowers the temperature of the directed air stream via evaporative cooling. The motor-driven fan is powered by at least one solar panel, which may be mounted on a water tank for holding the water supply of the water delivery system. Further, a rechargeable battery may be provided for providing power when the solar panel generates insufficient power.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to air conditioning systems, and particularly to a solar-powered air conditioning system suitable for dry, arid, desert conditions that relies upon evaporative cooling.
2. Description of the Related Art
A wide variety of air conditioning systems have been utilized to provide cool air for both personal comfort and for commercial and industrial purposes. Such systems typically include a compressor for liquefying a volatile substance, or refrigerant, housed within cooling coils. Thermal energy is extracted warm air passed over the cooling coils by a blower, causing the refrigerant to evaporate. The evaporated refrigerant is then passed through a condenser in the outside warm outside air, and the condensed refrigerant is subsequently compressed back into the liquid state and pumped through the cooling coils again. Such systems utilize a great deal of external energy, generally in the form of electricity, and the volatile substances used, such as Freon® (Freon is a registered trademark of E.I. Du Pont de Nemours and Company of Wilmington, Del.), frequently employ chlorofluorohydrocarbons, which are harmful to the environment.
In the southwestern United States, evaporative cooling systems are used that are sometimes referred to as “swamp coolers.” Such systems derive from the [practice of hanging a wet sheet or mat over an open window or screened porch and using a fan to draw hot air in through the wet sheet. The hot air and the water attempt to reach an equilibrium temperature, with heat being transferred from the hot air to the water, resulting in evaporation of water from the sheet and cooling of the air drawn into the structure.
While such systems are effective at cooling the air, nevertheless, there is a need for providing an air conditioning system for dry, arid regions that is low in cost and environmentally friendly. Thus, a solar-powered air conditioning system solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

The solar-powered air conditioning system is a low cost system for cooling air in dry, arid conditions through evaporative cooling. The system includes a motor-driven fan for producing a directed air stream. A water delivery system is in communication with an external water supply. The water is introduced into the directed air stream in droplets. Evaporation of the water droplets within the directed air stream lowers the temperature of the directed air stream via evaporative cooling.
Several methods are available for producing the water droplets. The external water supply may include a water tank or reservoir disposed above the directed air stream. The water tank may have a plurality of orifices defined therein, the water draining through the orifices in droplets by gravity feed. In order to promote the formation of small or micro (fine) droplets, a screen or mesh may be disposed beneath the water tank so that water draining through the tank is formed into water droplets by passing through the screen into the directed air stream. Alternatively, at least one atomizer could be positioned adjacent the fan to spray atomized droplets into the air stream. The atomizer is in fluid communication with an external source of water, and the water may be further charged into the atomizer by a pump. In another alternative, the atomizer may alternatively be built directly into the fan, with the blades of the fan having atomizer nozzles mounted in their front faces for spraying atomized droplets directly into the air stream.
The motor-driven fan is powered by at least one solar panel, which may be mounted on the roof or walls of the water tank, which holds the water supply of the water delivery system. Further, a rechargeable battery may be provided for providing power when there is insufficient sunlight to produce enough current from the solar panel to provide power to the fan. The rechargeable battery charged by the solar panel during the day, and provides power to the fan and pump, thus allowing both to operate at night.
These and other features of the present invention will become readily apparent upon further review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is diagrammatic view of a first embodiment of a solar-powered air conditioning system according to the present invention.

FIG. 1B is a plan view of the bottom wall of the water tank in the system of FIG. 1, showing the orifices defined therein.

FIG. 2 is a diagrammatic view of a second embodiment of a solar-powered air conditioning system according to the present invention.

FIG. 3 is a diagrammatic view of an alternative water delivery system for a solar-powered air conditioning system according to the present invention.

FIG. 4 is a diagrammatic view of another alternative embodiment of a water delivery system for a solar-powered air conditioning system according to the present invention.

FIG. 5 is an elevation view in section of a fan blade of the water delivery system of FIG. 4.

FIG. 6 is a schematic diagram of an electrical system for a solar-powered air conditioning system according to the present invention.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

Detailed Description of the Preferred Embodiments

FIG. 1A illustrates a solar-powered air conditioning system 10 according to the present invention that utilizes evaporative cooling to cool a directed air stream. System 10 is environmentally friendly, avoiding the use of refrigerants that may be toxic or harmful to the environment and avoiding the use of power grids that rely upon fossil fuels. The system 10 is relatively low cost in terms of materials and power consumption, and may be relatively portable. The system 10 may be used in open areas, and may be used to cool any desired structure. The system 10 is primarily intended for dry, arid regions, e.g., desert areas, since evaporation is retarded in humid environments.
Water 13 is initially supplied from a conventional external source of water, such as a natural body of water or conventional plumbing, to fill a water reservoir or water tank 12. Pure water, sweet water or salt water may be utilized as coolants. Similarly, any suitable liquid that will cool a directed air stream through evaporative cooling may be utilized, such as alcohol. Additionally, additives, such as scented substances, oils, fragrances, or alcohol, which has a higher rate of evaporation than water, may be added to the water.
As shown, water may be supplied from an external conduit 36 by a pump 34 to fill the water tank 12. The water tank 12 may be any suitable receptacle or reservoir for holding the water supply. In a first embodiment, the lower wall 15 of the tank 12 comprises a drip plate having a plurality of orifices 17 formed therethrough, as shown in FIG. 1B. The orifices 17 are very small in diameter, so that the water drips through these orifices 17 to form water droplets 14, which drip into directed air stream 16 to cool the air in air stream 16, as will be described in further detail below.
System 10 includes a fan 18 powered by electric motor 20, both of which may be of conventional design in the embodiment shown in FIG. 1A. Electric motor 20 is preferably a dc motor that may be powered by electricity generated by at least one solar panel 26 having an array of solar cells. For convenience and space efficiency, at least one solar panel 26 may be mounted on the sidewall of water tank 12, or on the roof 24 of tank 12, which also helps to keep the water cool by shading the reservoir from direct exposure to sunlight. The at least one solar panel 26 is in electrical communication with motor 20 via line 22. FIG. 1A illustrates four separate solar panels 26, with two being mounted on the sidewall of tank 12, and two being mounted on roof 24. The type, number and configuration of solar panels 26 depend upon the size of the system 10 and the area to be cooled. Fan 18 and water tank 12 may be formed from plastic, steel, aluminum, titanium, carbon fiber composites or any other suitable material.
Preferably, water tank 12 is positioned in an open area, allowing for solar exposure on solar panels 26. Solar panels 26 can, alternatively, be positioned away from tank 12, such as on the roof of a building or other structure. Preferably, tank 12 is positioned above the directed air stream 16 generated by fan 18, as shown in FIG. 1A, so that droplets 14 fall into air stream 16 under the force of gravity, with no further outside work being required. Water droplets 14 cool the air stream 16 through evaporative cooling, providing a cooling effect for the user. The air stream 16 may be directed to any area that requires cooling, e.g., into a building or other structure by ductwork, under canopies or tents in work areas, into vehicles, etc.
As further shown in FIG. 1A, a rechargeable battery 30 may be provided, and is connected to pump 34 via line 32. Rechargeable battery 30 may be of conventional design and is charged through electrical connection with solar panels 26. When solar panels 26 are placed within a sufficient source of light to generate power, rechargeable battery 30 charges as system 10 operates. When no sufficient light source is available, such as nighttime, system 10 can be operated by the power stored in rechargeable battery 30.
It should be understood that FIG. 1A is diagrammatic and does not represent an actual circuit schematic diagram. As shown in the closed circuit of FIG. 6, solar panel 26 is connected in parallel with rechargeable battery 30, allowing battery 30 to be charged as power is delivered to both pump 34 and motor 20. Alternatively, rechargeable battery 30 may be connected in series with solar panel 26 in a convention solar-powered charging circuit. As shown, a switch 28 is provided, allowing the user to selectively activate and deactivate pump 34. Similarly, a switch 29 is in series with motor 20, allowing the user to selectively activate and deactivate motor 20 of fan 18. It will be understood that switches 28 and 29 may be manually operated switches, or may be electronic switching circuits, and that the circuitry may further comprise an electronic switching circuit for automatically delivering electrical power to the pump 34, motor, 20, and fan 18 either directly from the solar panel 26 when the solar panel 26 produces sufficient power, or from the rechargeable battery 30 when power produced from the solar panel is insufficient. Alternatively, an electric compressor system may be used in conjunction with storage tank 12 to cool the water therein further, with the compressor being powered by solar panel 26 or rechargeable battery 30.
In the alternative embodiment of FIG. 2, a mesh screen 40 is mounted beneath water tank 12 by supports 38. Mesh screen 40 may be a stainless steel wire mesh screen, or any other suitable screen for producing fine droplets. Mesh screen 40 has a plurality of small openings formed therethrough, with the area of each small opening being smaller than the area of each opening formed through the lower wall of water tank 12. Water droplets 14 fall on mesh screen 40, and the small openings produce fine droplets 42, each having a volume smaller than that associated with droplets 14. Due to their smaller volumes, fine droplets 42 migrate to a greater extent within directed air flow 16, thus covering a larger volume of air and, have a greater surface area than large droplets to promote heat exchange, thereby producing a greater evaporative cooling effect and increasing the efficiency of air conditioning system 10.
In the alternative embodiment of FIG. 3, water tank 12 is replaced with at least one atomizer 46 for producing an atomized spray of water 48. In FIG. 3, three atomizers 46 are illustrated. However, it should be understood that the number and type of atomizers may vary within the scope of the present invention. Atomizers 46 are preferably positioned about the periphery of fan 18, as shown, so that the atomized water 48 sprays directly into directed air stream 16.
Pump 34, shown in FIGS. 1 and 2, pressurizes the water and feeds the water into atomizers 46 via supply line 44, as shown in FIG. 3. As described above with reference to FIG. 2, the smaller droplets, here in the form of an atomized mist, provide an enhanced cooling effect via evaporative cooling, because the small volume and mass of the droplets allows for greater rates of migration within air flow 16, and a greater surface area of the droplets for enhanced heat exchange, allowing a larger volume of air flow 16 to be cooled at a more rapid rate.
In another alternative embodiment, shown in FIG. 4, atomizers 52, similar in operation to those of FIG. 3, are formed directly in the fan blades 50 of fan 18. Atomizers 52 may be in the form of openings formed in fan blade 50, each being shaped as an atomizer nozzle, or may include separate atomizer nozzles mounted within openings 52. As shown in FIG. 5, each fan blade 50 includes a front face 53 and a rear face 54, with an open channel 58 being formed therebetween.
Water is received, under pressure, in a lower chamber 60 (supplied via pressurized water line 44, shown in FIG. 4) and passes into channel 58. The pressurized water is expelled through atomizer openings 52 to form an atomized mist, which directly enters the air stream 16 to effect cooling thereof via evaporative cooling.
System 10 relies on evaporative cooling in order to cool directed air stream 16, rather than relying on conventional compressor techniques, thus making system 10 an environmentally friendly system, which is further low cost to operate and build. Further, the system is solar-powered and utilizes the force of gravity in the embodiments of FIGS. 1 and 2 to deliver droplets 14 into air stream 16, thus providing an energy efficient system.
It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.

Claims

1. A solar-powered air conditioning system, comprising:

a fan for producing a directed air stream;

a coolant reservoir;

means for delivering coolant from the coolant reservoir into the directed air stream in droplets in order to produce evaporative cooling; and

a power source having at least one solar panel containing an array of solar cells for generating electrical power from the sun, the power source being electrically connected to the fan.

2. The solar-powered air conditioning system as recited in claim 1, wherein said coolant reservoir comprises a water tank adapted for holding water, the tank being mounted above the directed air stream, the tank having a lower wall, said means for delivering comprising a plurality of orifices defined in the lower wall of the tank, whereby the lower wall forms a drip plate, water draining through the drip plate by gravity and being formed into droplets.

3. The solar-powered air conditioning system as recited in claim 2, wherein said means for delivering further comprises a mesh screen disposed between said drip plate and the directed air stream, the mesh screen having a screen size dimensioned and configured for further dividing the water droplets into fine droplets.

4. The solar-powered air conditioning system as recited in claim 2, wherein said at least one solar panel is mounted on said water tank.

5. The solar-powered air conditioning system according to claim 2, wherein said coolant reservoir further comprises a roof mounted above said water tank.

6. The solar-powered air conditioning system according to claim 5, wherein said at least one solar panel comprises at least one solar panel mounted upon the roof over the water tank.

7. The solar-powered air conditioning system according to claim 2, further comprising a pump connected to said water tank for filling the water tank with water, said pump receiving electrical power from said power source.

8. The solar-powered air conditioning system according to claim 1, wherein said means for delivering comprises at least one atomizer connected to said coolant reservoir, the atomizer being disposed to spray coolant into the directed air stream in an atomized mist.

9. The solar-powered air conditioning system according to claim 1, further comprising a fluid conduit extending between said coolant reservoir and said fan, said means for delivering further comprising:

a plurality of fan blades disposed upon said fan, the fan blades having fluid channels defined therein; and

a plurality of atomizer nozzles disposed upon each of the fan blades, the nozzles communicating with the fluid channels in order to spray an atomized mist of coolant into the directed air stream.

10. The solar-powered air conditioning system according to claim 1, wherein said power source further comprises:

at least one rechargeable battery;

a charging circuit for recharging the battery from current generated in said at least one solar panel; and

switching means for delivering electrical power to said fan directly from said solar panel when said solar panel delivers sufficient power and for delivering electrical power to said fan from said rechargeable battery when said solar panel delivers insufficient power to said fan.

11. The solar-powered air conditioning system according to claim 1, further comprising a dc electric motor driving said fan, the motor being electrically connected to said power source.