Outdoor air cooling apparatus and method

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.

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.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Illustrated inFIG. 1is the basic scheme for practicing the invention.

A fan10is suspended from the ceiling12or 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 by14. The fan10may also be a freestanding fan. The fan10preferably oscillates to provide better moving air distribution over the area generally in front of the fan.

Mounted on open fan grillwork16or otherwise in the fan air stream are a plurality of very small nozzles18preferably having a venturi internal configuration for best atomization. The nozzles18are supplied with high pressure water through one sixteenth inch inside diameter tubing20. A small vibratory, rotary or piston pump22capable of generating 250 to 600 pounds per square inch (psi) of water pressure supplies the nozzles18. The nozzles18are selected with the pump22to 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 nozzles18of 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 pump22through a filter24from a reservoir or water line26. Electrically connected and physically attached to the pump22is a controller28for 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. 2illustrates a multiple fan installation for a large venue. The fans30may be mounted on the ceiling32or walls or columns of a pavilion for example. Each fan30is equipped with a plurality of nozzles34positioned to direct a spray of water droplets into the moving air produced by the fan propellers. The fans30are electrically connected36to a central controller38whereby the fans30can be individually controlled, controlled in blocks or controlled as a whole.

The nozzles34are supplied through one-sixteenth inch diameter tubing40to the individual fans30and as required larger tubing to small solenoid valves42which control the flow of water to the nozzles on each fan. The small solenoid valves42are electrically connected to a second controller44whereby the nozzles for each fan can be cycled on and off as required. The two controllers38and44are coordinated46to provide water flow only when the corresponding fan is operating. A single pump48supplies the nozzles34. As many as 50 nozzles34can 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 valves42can be 12 or 24 volt valves.

Illustrated inFIG. 3is the schematic of a cycle controller where the fan is on continuously and illustrated inFIG. 4is the associated dual high pressure pump. In this example the relay timer or controller50includes a master switch52with 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 receptacle54directly connected to the line cord and into which the fan motor may be plugged.

The controller50is connected to the dual pumps56and58by power lines60and62. Referring toFIG. 4the pumps56and58are connected hydraulically in series by the water conduit64from the output of pump56to the input of pump58. The pumps56and58are electrically connected in parallel60, however, the electrical circuit is in series68through overheat protection66such as a thermo-couple on pump56. The entire controller50, pumps56and58and switch52are 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.