Fluid sprinkling – spraying – and diffusing – Processes – Of weather control or modification
Reexamination Certificate
2000-05-09
2004-02-17
Kim, Christopher (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Processes
Of weather control or modification
C239S014100, C239S014200
Reexamination Certificate
active
06691926
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a snow making system and, more particularly, to an apparatus and method that makes snow by a fan and turbine that produces a high-velocity cooled air that atomizes water, thereby creating a stream of frozen water seeds (nuclei) and a stream of small water particles, and blowing the mixed streams across a distance to freeze and form snow.
Snow making is critical to ski resorts. This is because the amount of snow and the length of time the snow is present dictate whether a resort has financially successful or unsuccessful season. Generally, as the amount of snow increases, so does the length of time the snow is present. The longer the length of time snow is present, the longer skiers are able to use a resort. However, unpredictable weather patterns can mean poor ski conditions and financial ruin to a ski resort.
Therefore, ski resorts have long recognized the need for snow making capability. However, snow making has been capital and labor intensive. Essentially, two different systems have been utilized to make snow—an airless system and an air (i.e., air/water) system. Typically, in an air/water system, a ski resort contains a central air compressor and water pumping center located near the base of the resort. From the center, air and water lines run along the ski slopes. At various points of the ski slopes, provision is made for tapping into the air and water lines. In an “airless” system, pressurized water lines and electrical lines (or other motorized means to power the snowmaking machine) are utilized to make snow.
One very early air/water system is simply a nozzle (i.e., snowgun) that combines high amounts of compressed air and relatively low amounts of pressurized water. The compressed air and pressurized water are simultaneously discharged from the snowgun. As the compressed air and pressurized water exit the snowgun, the expansion of air creates frozen nuclei, breaks up the water into small particles, and propels it across the slope. The cold, ambient air completes the process and causes the water to freeze into snow. However, the gun design produces relatively little snow despite the large amounts of air used. The high cost of producing the compressed air is the major drawback of this type of system.
In the airless systems, compressed air is used to a limited extent, if at all. Instead, a fan typically draws ambient air into the system housing. Downstream of the fan is an air-atomizing nozzle(s) that produces very small water particles (typically less than 50 microns) that immediately freeze to form ice nuclei (seeds), as well as water nozzles that produce water droplets. The ice nuclei and water droplets mix with the ambient air from the fan and are propelled across the slope, forming snow before it reaches the ground. Although more energy efficient than the compressed air systems, they suffer the capital cost disadvantage of having the need for a portable internal combustion engine accompanying the system or, in the alternative, an electrical distribution system across the ski slopes. They are also limited to making snow at temperatures at 26 degrees F. or colder. In addition, the large size (500+ lbs.) and complexity of these systems makes it difficult to move them (and virtually impossible with a snowmobile) and prohibits mounting on towers to take advantage of the efficiency of making snow from an elevated height.
A hybrid system employing features of both the air and airless systems is found in U.S. Pat. No. 3,945,567. Compressed air is used to drive a motor that, in turn, drives air-impeller blades. The blades draw in ambient air. Exhaust air from the motor is combined with compressed air and pressurized water to form a combined stream of very small water particles. The combined stream and the ambient air are mixed. After the mixed stream exits the apparatus, additional water is sprayed into the mixed stream, where it is thereupon converted into snow when ambient temperatures are 26 degrees F. or less. An advantage of this design is that the use of compressed air eliminates the need for electric or internal combustion motors in close proximity to the apparatus. However, disadvantages to this design include the relatively inefficient motor and, although the compressed air is relatively dry, the moisture in the air will condense out as the temperature drops and cause the motor to freeze up.
In another hybrid system, U.S. Pat. No. 4,593,854 provides a water driven turbine to drive a downstream fan to draw in ambient air. An annular air/water manifold ring is downstream of the fan. The air/water manifold supports nucleating (i.e., water atomizing) nozzles or nucleators and snowmaking nozzles positioned between the former. Air and water mixtures are discharged downstream and outside of the apparatus. A water manifold is concentric to and surrounds the air/water manifold, the former of which supports nucleating nozzles. The water manifold is not used in marginal snowmaking conditions. Some of the disadvantages to this design include: 1) any water remaining within the water turbine will freeze after shutdown and cause the turbine to freeze up, and even blowing out the system will most likely leave residual water; 2) water pressure varies greatly from the top and the bottom of the mountain (100 to 500 psi or greater), leaving little “power” at the top of the mountain; 3) nucleating/air atomizing nozzles tend to freeze up unless an external heat source is supplied. Commercially available electric-fan type snowmaking machines provide electric heaters to ensure this does not occur, but with a water-powered machine electricity is not available for this function.
U.S. Pat. No. 4,597,524 is similar to U.S. Pat. No. 4,593,854 and thus has similar disadvantages. Both are similar in that they use pressurized water to drive a fan, rather than compressed air as in U.S. Pat. No. 3,945,567. Specifically, in U.S. Pat. No. 4,597,524, air-water atomizing nozzles are positioned in the fan-induced air stream and within (or outside) a shroud that surrounds the fan. A water powered turbine drives the axial fan.
U.S. Pat. No. 4,682,729 also uses the nucleating nozzle, water droplet, fan concept of the airless system and is powered by compressed air. However, a reaction fan is used, in addition to the creation of separate zones of ice nuclei and water droplets. Compressed air is sent to the reaction fan which expands the compressed air and rotates the fan blades. The rotation of the fan blades draws in ambient air. Downstream of the reaction fan is the nucleating nozzle which is centrally disposed within the system housing. The nucleating nozzle combines the compressed air with water to expel ice nuclei into the drawn-in ambient air. Downstream of the nucleating nozzle and at the exit of the system are water nozzles that expel water droplets into the mixture of ice nuclei and drawn-in ambient air. Again, this design has the disadvantage of air-atomizing nozzle freeze up unless electrically heated. Also, this design has long slender tubing exposed to cold ambient air that will rapidly clog with ice that forms when water condenses out of the compressed air. Additionally, the efficiency of this system is questionable—the air/water operating ratio of 22:1 at 35 degrees F. is no better than existing air/water guns.
Additional references to snow making apparatus are found in U.S. Pat. Nos. 4,813,598 and 4,901,920.
As can be seen, there is a need for an apparatus for and method of making snow, particularly one that minimizes the need for expensive compressed air. Another need is to eliminate the provision of an electrical power distribution system, or an expensive, cumbersome internal combustion engine, to drive the snow making system. Also needed is a snow making apparatus and method that can be effectively used at higher ambient temperatures, thus increasing the number of environments in which the apparatus and method can be used. Another need is for a snow making apparatus that is not prone to freeze up during operation or shutdow
Caglar Esq. Oral
Honeywell International , Inc.
Kim Christopher
LandOfFree
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