Abstract:
In evaporative cooling by injecting extremely fine water droplets into an airstream, the addition of cyclic injection provides superior control of the temperature drop of the air. The cyclic operation of the injection enables effective air cooling of outdoor and semi-outdoor areas, such as outdoor restaurants, even under conditions of high humidity. Small high pressure pumps that can be cycled on and off every few seconds for many millions of cycles make the air cooling method practical and effective.

Description:
This application claims the benefit of provisional patent application No. 60/395, 679, filed Jul. 15, 2002. 

   BACKGROUND OF THE INVENTION 
   The field of the invention pertains to air cooling and air conditioning apparatus and methods, and, in particular, to cooling semi-enclosed and open air areas where people congregate. These areas are very common in warm and hot climates and somewhat less common, but not unknown, in seasonally warm climates. 
   Air conditioning, even for fully enclosed areas, remains a very energy intensive activity because the laws of thermodynamics set rigorous limits to efficiencies that can be approached even with excellent insulation. With semi-enclosed or open air areas such as sports arenas, outdoor restaurants, outdoor arenas, roof-only concert facilities and band shells and other outdoor venues, full air conditioning is completely impractical. Therefore, to cool areas without walls or only partial walls, a different approach to air cooling is required such as continuous spraying of water into a blowing airstream. 
   SUMMARY OF THE INVENTION 
   The invention comprises improvements in the well known effect of evaporative cooling where air is passed over a water bath, air is passed through a venturi to draw water into the air or water is sprayed into the air. As the water evaporates, the heat of evaporation causes the air temperature to fall noticeably. Unfortunately the result is a noticeable increase in humidity. 
   Applicant has discovered that by cyclically pumping water at very high pressure through small tubing and nozzles into an air stream, superior cooling without excessive dampness can be created in outdoor and semi-outdoor areas, such as outdoor restaurants. In the simplest application, several nozzles are placed on a fan and connected by very small tubing to a small electric water pump and timing controller. The combination of fan and pump can be controlled to provide continuous operation of both or a time percentage of pump operation during continuous or intermittent fan operation. 
   Use of the very high pressure water and small nozzles causes a severe pressure drop through the nozzles in turn causing very fine droplets to exit the nozzles. The result is evaporation of water almost instantly, thereby preventing droplets of water from descending on patrons standing and sitting below or nearby. Controlling the water pump cycle permits effective cooling despite ambient conditions of high humidity with high temperature. These pumps may be multiple stage pumps to reach the water pressure required. 
   Small high pressure water pumps that can be cycled on and off every few seconds for many millions of cycles make the air cooling method practical and effective. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates schematically a fan and pump having a plurality of separate nozzles thereon; 
       FIG. 2  illustrates schematically a multiple fan installation with nozzles on the fans and single pump supply; 
       FIG. 3  is a schematic diagram of a cycle controlled installation; and 
       FIG. 4  is a top view of a miniature high pressure dual pump, 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Illustrated in  FIG. 1  is the basic scheme for practicing the invention. 
   A fan  10  is suspended from the ceiling  12  or upper wall of a semi-enclosed area and directed somewhat downwardly and generally toward an area below to be cooled, such as an outdoor restaurant seating area generally denoted by  14 . The fan  10  may also be a freestanding fan. The fan  10  preferably oscillates to provide better moving air distribution over the area generally in front of the fan. 
   Mounted on open fan grillwork  16  or otherwise in the fan air stream are a plurality of very small nozzles  18  preferably having a venturi internal configuration for best atomization. The nozzles  18  are supplied with high pressure water through one sixteenth inch inside diameter tubing  20 . A small vibratory, rotary or piston pump  22  capable of generating 250 to 600 pounds per square inch (psi) of water pressure supplies the nozzles  18 . The nozzles  18  are selected with the pump  22  to provide very fine atomization from the combination. The water spray is preferably completely vaporized before it can strike any persons below. The result is a very pleasant cooling effect without the dampness associated with sprays that strike persons before completely evaporating. For example, the water droplets are sprayed through nozzles  18  of 0.008 to 0.072 inches orifice diameter at 250 to 600 psi. The resulting droplet sizes average about 10–25 microns, resulting in evaporation of the droplets in a fraction of a second after ejection from the nozzle. The heat of evaporation is extracted from the air almost instantly, resulting in a very effective cooling of the air without any mechanical refrigeration cycle. Water pressures to 1000 psi have been found effective to properly atomize the water ejected from the nozzles. 
   Water is fed to the pump  22  through a filter  24  from a reservoir or water line  26 . Electrically connected and physically attached to the pump  22  is a controller  28  for setting the percentage of time or cycle for the pump. 
   For example, the pump controller might be set for 7.5 seconds on and 7.5 seconds off and indefinitely cycle for these time periods. The time periods may be equal or unequal, however, for cyclic operation that preserves proper operation of the pump there are minimum times on and off that can be set. These limits have been set at 1.9 seconds on (2% on) and 1.9 seconds off (98% on). Separate settings provide 100% on and full off for the pump. 
     FIG. 2  illustrates a multiple fan installation for a large venue. The fans  30  may be mounted on the ceiling  32  or walls or columns of a pavilion for example. Each fan  30  is equipped with a plurality of nozzles  34  positioned to direct a spray of water droplets into the moving air produced by the fan propellers. The fans  30  are electrically connected  36  to a central controller  38  whereby the fans  30  can be individually controlled, controlled in blocks or controlled as a whole. 
   The nozzles  34  are supplied through one-sixteenth inch diameter tubing  40  to the individual fans  30  and as required larger tubing to small solenoid valves  42  which control the flow of water to the nozzles on each fan. The small solenoid valves  42  are electrically connected to a second controller  44  whereby the nozzles for each fan can be cycled on and off as required. The two controllers  38  and  44  are coordinated  46  to provide water flow only when the corresponding fan is operating. A single pump  48  supplies the nozzles  34 . As many as 50 nozzles  34  can be supplied simultaneously by one or more small electromagnetic pumps or by larger pumps. 
   Despite the high water pressures (up to 1000 psi) very light weight small diameter plastic tubing can be used along with corresponding small brass fittings. Complicated high or standard (110 v) voltage electrical systems can also be avoided since the solenoidal valves  42  can be 12 or 24 volt valves. 
   Illustrated in  FIG. 3  is the schematic of a cycle controller where the fan is on continuously and illustrated in  FIG. 4  is the associated dual high pressure pump. In this example the relay timer or controller  50  includes a master switch  52  with a dial knob (not shown) that can be turned to select the cycle time for the controller or turn the controller completely off. Also included is an AC receptacle  54  directly connected to the line cord and into which the fan motor may be plugged. 
   The controller  50  is connected to the dual pumps  56  and  58  by power lines  60  and  62 . Referring to  FIG. 4  the pumps  56  and  58  are connected hydraulically in series by the water conduit  64  from the output of pump  56  to the input of pump  58 . The pumps  56  and  58  are electrically connected in parallel  60 , however, the electrical circuit is in series  68  through overheat protection  66  such as a thermo-couple on pump  56 . The entire controller  50 , pumps  56  and  58  and switch  52  are contained within a plastic enclosure about five inches on a side and three inches in depth. 
   Depending on the length of one-sixteenth inches high pressure tubing this particular pump can provide sufficient water to four nozzles on one fan at a minimum or considerably more nozzles or additional fans. For example, 25 to 50 or more nozzles can be suppled with this particular pump and controller described above. Through testing and experience and depending on prevailing wind conditions each nozzle is effective at cooling 100 square feet of venue. With the large number of nozzles that can be supplied by the above pump and controller which draws about 46 watts of electric power, a very large venue can be cooled at the equivalent electric cost of a small incandescent light bulb. Most important, the cooling is effective at high humidity (above 85%) with high temperature (above 90 degrees F.). By purposefully cycling the apparatus, cooling can be effected without increasing the level of humidity sensible to individuals within the cooled venue.