The Compleat Snowmaker - Mountain View Technologies, Inc.

The Compleat Snowmaker
The Contemplative Snowmaking Primer
being a seminar of Man Made Snow and its
process, not unworthy of the perusal of most
snowmaking experts.
Presented by
Yaro “Izaak” Stanchak
Mountain View Technologies, Inc.
Jiminy Peak LMS 4/16/13
4/16/2013
www.the‐snowman.com
1
The Compleat Snowmaker Topics
4/16/2013
www.the‐snowman.com
2
Miracle Water
• H2O – Water is comprised of two atoms of Hydrogen and one atom of Oxygen.
• Liquid Water has a density of 62.4 lbs./ft3 .
• Ice, frozen water, has a density of 57.4 lbs./ft3 and is ~9% lighter than liquid water.
• Good manmade snow has a density of 25‐30 lbs./ft3.
• There are 15 different known types of ice, the most prevalent and common is Ih.
• Ih freezes into a hexagonal crystal shape on a molecular level.
4/16/2013
www.the‐snowman.com
3
Types of Ice
Wikipedia
4/16/2013
www.the‐snowman.com
4
Snow Crystal
www.SnowCrystals.com
4/16/2013
www.the‐snowman.com
5
Importance of Nucleation
• By definition, Water freezes at 32oF.
• A nucleation particle is required to create an ice crystal.
• There are many types of nucleation particles and each type initiates freezing at a specific temperature in oF. The best nucleation point is a very small ice particle.
• During the entire freezing process the Water remains at 32oF as it changes phase – from liquid to solid.
• 144 BTU is released into the environment for every pound of Water frozen.
4/16/2013
www.the‐snowman.com
6
Ice Particle Formation
UCL
4/16/2013
www.the‐snowman.com
7
Role of Evaporative Cooling
• One gallon of Water (8.35 lbs) has a cooling capacity of 8,976 BTU.
• In theory, one gallon of water can cool to freezing 7.47 gallons of water – in reality it is very variable.
• The amount of water evaporated is very dependent on the Relative Humidity and Dry Bulb temperature.
• The impact of this cooling is greatest in high temperature snowmaking, below 18oF it rapidly diminishes.
• Cold temperatures and an abundance of ambient air movement are critical for continuous snowmaking.
4/16/2013
www.the‐snowman.com
8
The Freezing Process and Energy
• Minute ice particles act as freezing points in the fine water spray plume from a snow gun.
• Contact with the spray water droplets initiates rapid freezing into ice crystals assuming adequate cooling.
• Many of the formed ice crystals will complete the freezing process on the ground surface.
• One gallon of Water (8.35 lbs.) releases 1,252 BTU as it freezes.
• 1,000 gpm of flow requires 1,252,000 BTU/min or 21,988 kW or 29,497 hp of heat energy to be absorbed into the surrounding atmosphere.
4/16/2013
www.the‐snowman.com
9
Snow Gun Theory
• Superior nucleation of small ice crystals is the largest contributor to warm and medium temperature snowmaking performance.
• The water spray pattern and droplet size distribution follows in importance. Water pressure above 275 psig makes a big difference!
• The proper mixing of ice nuclei and water droplets, in conjunction with long hang time, creates the snow particle. A following wind improves performance!
• Fixed water flow snow guns have a definite, but narrow, “sweet spot”. Variable flow snow guns have several “sweet spots”, thereby extending the usable temperature range. Applies to Low “E” and fan guns!
4/16/2013
www.the‐snowman.com
10
Snow Gun Examples
Multiple Valves for Temperature Range
4/16/2013
www.the‐snowman.com
Multiple Water Jets
11
Snow Quality
Nucleation
4/16/2013
Freezing
www.the‐snowman.com
Curing
12
Snow Quality Chart
• P++ A Skiers Nirvana
• P+ Powder Snow that cannot be packed into a snowball
• P* Snow that can be packed into a easily crumbled snowball • P Snow that produces a firm white snowball • P‐ Snow that produces a gray snowball
• P‐ ‐ Snow that is wet and generally ugly
4/16/2013
www.the‐snowman.com
13
Wet Bulb Temperature
• Wet Bulb Temperature is the most reliable and consistent indicator of a snow gun’s snowmaking performance.
• Wet Bulb is calculated from the dry bulb temperature and percent relative humidity. This value takes into account the varying humidities for a given temperature.
• For snowmaking, wet bulb temperature is particularly useful in temperatures 18oF and above.
• Higher elevations improve wet bulb performance.
4/16/2013
www.the‐snowman.com
14
Snow Plume Dynamics
• As water freezes in the snowmaking plume the temperature and humidity within the plume increase markedly.
• Any snow guns operating downwind of will be influenced by a higher temperature and humidity.
• The highest temperatures and humidity values are within the center of the snow plume.
• The dampest snow will be deposited below the center of the snow plume.
4/16/2013
www.the‐snowman.com
15
The Future
4/16/2013
www.the‐snowman.com
16