SNOWMAKING METHODS
A method and apparatus for producing artificial snow is provided. The method and apparatus include controls and operating parameters for given ambient conditions to assure that fluid droplets are at equilibrium temperature before mixing with ice nuclei to produce artificial snow.
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This application claims priority from and the benefit of U.S. Provisional Application No. 60/985,481 entitled SNOWMAKING METHODS, filed Nov. 5, 2007, which is hereby incorporated by reference.
BACKGROUNDThe application generally relates to snowmaking. The application relates more specifically to a method and apparatus for producing artificial snow.
Snowmaking is critical to winter sporting resorts because the amount of snow and the length and period of time that snow is present dictate whether a resort has a financially successful season. Generally, as the amount of snow increases, so does the length of time the snow is present. The earlier and the longer the length of time snow is present, the longer skiers, snowboarders, and the like are able to use a resort. However, unpredictable weather patterns can produce winters with low outputs of natural snow.
Therefore, winter sporting resorts have long recognized the need for making artificial snow. However, snowmaking is often capital and labor intensive for the resort. Generally, two different types of snowmaking systems are used, namely, airless systems and air (i.e., air/water) systems. Typically, in an air/water system, a ski resort has a water pumping center and an air compressor located near the base of the resort, e.g., at a lake or pond. From the center, water and air lines run uphill along the ski slopes. At various locations, 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 used to make snow.
An example air/water system is a snowgun that includes a nozzle 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 smaller particles, and propels it across the slope. Cold ambient air completes the freezing process and causes the water to form into artificial snow. However, such gun designs produce relatively little snow despite the large amounts of air used. The high cost of producing compressed air is a disadvantage of this type of system. Such air/water systems are usually ineffective above 28 degrees Fahrenheit (−2 degrees Celsius) (wetbulb), and their maximum output is typically 17 to 20 gallons/minute (64-76 liters/minute) at 28 degrees Fahrenheit (−2 degrees Celsius) (wetbulb).
An example airless system is a low-pressure snow cannon that includes a propeller (e.g., a fan) for producing a main air stream into which freezing nuclei are sprayed by means of nucleator nozzles and small water droplets are spayed by means of water nozzles. The nucleator nozzles are constructed as water/air nozzles, and they are operated with compressed air and water under pressure and atomize a water/air mixture. The compressed air relaxes as it issues from the nucleator nozzles and thus cools water droplets of the water/air mixture to well below the freezing point so that small ice crystals are formed. The droplets discharged by the water nozzles collide and/or intersect with these freezing nuclei and form snow crystals. Although such snow cannons generally have a greater output than snowguns, they also are usually ineffective above 28 degrees Fahrenheit (−2 degrees Celsius) (wetbulb).
Current meteorological evidence indicates that, on average, the global climate is warming. Winters are becoming shorter, as well as the length of the skiing season. The amount of natural snow falling at winter sporting resorts is also declining. It is estimated that a 1 degree Celsius increase in average temperature will reduce the length of the skiing season by about 25%. It is therefore important for winter sporting resorts to be able to make snow at higher temperatures and to make greater amounts of artificial snow when ambient weather conditions permit.
Intended advantages of the disclosed methods satisfy one or more of these needs or provide other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the claims, regardless of whether they accomplish one or more of the aforementioned needs.
In an embodiment, a control system is provided that monitors snowmaking conditions (ambient temperature, relative humidity, etc.), as well as operational parameters (electric power supply, water supply, etc.), and operates a snowmaking device in accordance with pre-programmed parameters or instructions to maximize snow production.
SUMMARYIn one embodiment of the disclosure, a method of producing artificial snow is disclosed that includes providing a mass of propelled fluid through a housing having an inlet and an outlet, injecting a spray of liquid droplets into the propelled fluid, and injecting ice crystals and additional liquid droplets into the mass of propelled fluid from a structure disposed within the housing proximate the outlet.
Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.
In one embodiment, the pressurized liquid may be water and the compressed fluid may be air. However, the liquid and fluid are not limited to water and air, respectively. That is, both liquid and fluid may be composed partially or entirely of materials other than water and air. The term ice, as used herein, refers to a solid state of a substance resembling ice, and is not limited to water in a solid state.
As shown in
Referring to
The distribution system 85 includes a plurality of peripheral nozzles 78, such as V-jet nozzles, arranged concentrically in three concentric circles at outlet 56 of housing 36. In one embodiment, nozzles 78 may be arranged in one, two, three or more than three concentric circles. In another embodiment, nozzles 78 may be arranged in two concentric circles. Distribution system 85 is in fluid communication with a pressurized liquid supply through a valve assembly 82 and a manifold 81 attached to a rear surface (not shown) of distribution system 85. In one embodiment, the peripheral nozzles 78 in distribution system 85 are inclined inward at an angle between about 5 degrees and about 85 degrees so that during operation of snowmaking apparatus 10 the spray pattern of each nozzle 78 is directed into the fluidflow exiting housing 36 to inject the formed liquid droplets into the fluidflow. In another embodiment, the peripheral nozzles 78 in distribution system 85 are inclined inward at an angle between about 5 degrees and about 25 degrees. In another embodiment, the peripheral nozzles 78 are inclined inward at an angle between about 10 degrees to about 20 degrees. In another embodiment, the nozzles 78 are inclined inward at an angle of about 15 degrees. In one embodiment, the distribution system 85 has three concentric circles of nozzles 78, and the nozzles 78 on the inside circle are inclined inward at an angle between about 10 degrees and about 18 degrees, and preferably about 12 degrees, and the nozzles 78 on the middle circle are inclined inward at an angle between about 8 degrees and about 15 degrees, and preferably about 10 degrees, and the nozzles 78 on the outside ring are inclined inward at an angle between about 5 degrees and about 10 degrees, and preferably about 8 degrees. For reference, a 0 degree inclination would be parallel to the fluidflow, and a 90 degree inclination would be perpendicular to and directed inwardly towards the fluidflow.
In one embodiment, nozzles 78 produce a flat spray pattern in the shape of a triangle having a spray angle of between about 15 degrees to about 65 degrees. In another embodiment, the spray angle is between about 25 degrees and about 50 degrees. In another embodiment, nozzles 78 produce a flat spray pattern in the shape of a triangle having a spray angle of between about 25 degrees to about 40 degrees. In yet another embodiment, nozzles 78 produce a flat spray pattern in the shape of a triangle having a spray angle of about 25 degrees. In still another embodiment, the spray pattern may be in a shape other than a flat triangle, for example, the spray pattern may be a hollow conical or cylindrical shaped pattern.
During operation of snowmaking apparatus 10, liquid is supplied to nozzles 78 under a pressure between about 100 pounds per square inch (psi) and 600 psi to form liquid droplets, which are injected into the propelled fluid. The nozzles 78 are configured to produce water droplets having a mean droplet size for a particular water pressure. Nozzles 78 may be selected to produce droplets having mean droplet sizes of between about 200 microns to about 1000 microns. In another embodiment, nozzles 78 are selected to produce droplets having a mean droplet size of between about 300 microns to about 900 microns. The droplet size may increase in this range as ambient temperature decreases. Droplet size less than 200 microns may not have enough mass after evaporative cooling to effectively form snow at the point of mixing with the ice nuclei. Also, droplet size of less than 200 microns may allow wind conditions and convective air currents to adversely affect the ability to direct snow production to a desired area. Droplet size of greater than 1000 microns produce a less desirable ski surface.
An additional parameter necessary to snow formation is the ratio of ice nuclei to water droplets. It has been determined that a ratio of ice nuclei to water droplets in a range of about 0.7:1 to about 1.2:1 resulted in improved conversion of bulk water to snow for snowmaking. In one embodiment, it has been determined that a ratio of ice nuclei to water droplets greater than or equal to 1:1 results in improved conversion of bulk water to snow for snowmaking.
In one embodiment, water droplets are sprayed out of nozzles 78 under pressure of about 300 pounds per square inch (2067 kilopascals). The volume of flow, droplet size and number of droplets of liquid from the nozzles 78 may be controlled by valves incorporated into the individual nozzles 78, or the nozzles 78 may be controlled only by the flow of pressurized fluid in the manifold, or a combination thereof. By controlling the flow of liquid from the nozzles 78, the amount of bulk water used to form snow may be controlled. A plurality of peripheral V-jet nozzles 78 are arranged in three concentric circles forming outer ring system 85 at the circumference of cylindrical housing outlet 56, where they are in fluid communication with a pressurized water supply.
In another embodiment, liquid is supplied to nozzles 78 under a pressure between about 175 pounds per square inch (psi) and 600 psi to form liquid droplets, which are injected into the propelled fluid. In another embodiment, liquid is supplied to nozzles 78 at a pressure of between about 250 psi and about 500 psi. In yet another embodiment, liquid is supplied to the nozzles 78 at a pressure of about 300 psi.
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Inner liquid ring 108 is in fluid communication with inner ring peripheral nozzles 78A, middle liquid ring 110 is in fluid communication with middle ring peripheral nozzles 78B, and outer liquid ring 112 is in fluid communication with outer ring peripheral nozzles 78C. Inner liquid ring 108 is also in fluid communication with inner fluid ring connection 126A, middle fluid ring 110 is also in fluid communication with middle fluid ring connection 126B, and outer fluid ring 112 is also in fluid communication with outer fluid ring connection 126C. In one exemplary embodiment peripheral nozzles 78A, 78B, and 78C are radially oriented inward towards housing central axis 121 along spray direction 120 by an inclination angle as discussed above.
In an alternative embodiment, liquid rings 108, 110, and 112 are each made from three independent circular pipes (not shown) that form distribution system 85. In yet another embodiment, each of three liquid rings 108, 110, and 112 may be operated independently of one another, with or without simultaneous operation of structure 84.
In one embodiment, valve assembly 82 is configured to regulate pressurized liquid to the middle liquid ring connection 126B and inner liquid ring connection 126A while permitting pressurized liquid to flow to the structure 85 and outer liquid ring connection 126C unregulated, or in other words, without valving.
While only certain features and embodiments of the invention have been illustrated and described, many modifications and changes may occur to those skilled in the art (for example, variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, such as, but not limited to temperatures, pressures, mounting arrangements, use of materials, colors, orientations, etc., without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (that is, those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the claimed invention). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.
Claims
1. A method for producing artificial snow, comprising:
- providing a mass of propelled fluid through a housing having an inlet and an outlet;
- injecting a spray of liquid droplets into the propelled fluid; and
- injecting ice crystals and additional liquid droplets into the mass of propelled fluid from a structure disposed within the housing proximate the outlet.
2. The method of claim 1, wherein the spray of liquid droplets is injected into the propelled fluid from a circumferential position proximate the housing outlet.
3. The method of claim 1, wherein the liquid droplets have a mean particle size between about 200 microns and about 1000 microns.
4. The method of claim 1, wherein the liquid droplets have a mean particle size of between about 300 microns and about 900 microns.
5. The method of claim 1, wherein the mass of propelled fluid is provided at between about 6,000 cfm and about 25,000 cfm.
6. The method of claim 1, wherein the additional liquid droplets are injected into the propelled fluid at an inclination angle of between about 5 degrees to about 85 degrees.
7. The method of claim 1, wherein the additional liquid droplets are injected into the propelled fluid at an inclination angle of between about 10 degrees to about 20 degrees.
8. The method of claim 1, wherein the additional liquid droplets are injected into the propelled fluid from at least two concentric circles surrounding the perimeter of the propelled fluid.
9. The method of claim 8, wherein the additional liquid droplets are injected into the propelled fluid from three concentric liquid rings.
10. The method of claim 8, wherein the three concentric rings inject fluid from an inner liquid ring having a nozzle at an inclined angle between about 10 degrees and about 18 degrees, a middle liquid ring having a nozzle at an inclined angle between about 8 degrees and about 15 degrees, and an outer liquid ring having nozzle at an inclined angle between about 5 degrees and about 10.
11. The method of claim 1, wherein the spray of additional liquid droplets are injected with a flat triangular spray pattern of about 15 degrees to about 65 degrees.
12. The method of claim 1, wherein the spray of additional liquid droplets are injected with a flat triangular spray pattern of about 25 degrees to about 50 degrees.
13. The method of claim 1, wherein the ratio of liquid droplets and additional liquid droplets to ice crystals is about 0.7:1.
14. The method of claim 1, wherein the ratio of liquid droplets and additional liquid droplets to ice crystals is between about 0.7:1 to about 1.2:1.
15. The method of claim 1, wherein the liquid droplets, additional liquid droplets and ice crystals inject a liquid into the propelled fluid at a rate of up to about 150 gal/min at 18 degrees F. (wet bulb).
Type: Application
Filed: Nov 4, 2008
Publication Date: May 7, 2009
Applicant: JOHNSON CONTROLS TECHNOLOGY COMPANY (Holland, MI)
Inventor: Jay H. COLLINS (Washoe Valley, NV)
Application Number: 12/264,389