How to make indoor snow

To produce snow all year, a controlled environment is required. The method is based on similar principals to those used for the outdoor snowmaking, however all of the cooling has to be provided by some form of refrigeration. Because the area is enclosed and smaller than the outdoor ski slopes, the snow is subject to a higher use factor, thus the quality of the snow and the environment becomes very important, especially for snow play areas. With outdoor areas, a small area of poor snow may go unnoticed whereas in an indoor facility the whole area has to be maintained.

When snowguns are used outdoors, any water vapor produced by evaporation is diffused into the ambient air, however with an enclosed environment, if this is not controlled, the resulting rise in humidity would significantly affect the snow. If allowed to reach saturation it prevents the formation of snow crystals. As with nature, the temperature and humidity of the surrounding environment will determine the type and size of snow crystals which can be produced.

The maximum cooling load that will occur during a normal operating cycle will be during the snowmaking process when all of the latent heat from freezing the water particles has to be removed instantaneously. Thus the building's cooling system has to be capable of responding rapidly to remove this amount of heat.

To reduce the problems with the humidity and to make full utilization of the cooling, the snowguns for indoor use need to be highly efficient. This will enable virtually all of the water to be turned to snow and reduce the evaporation losses to an absolute minimum. Because there are no additives used in the process, the snowgun design incorporates a self nucleating system to start the crystal growth process. The guns produce finer droplets than normal outdoor guns (outdoor droplets can range from 100 to 250 microns in diameter, indoor droplets are in the range of 10 to 50 microns.)

The environment has to be controlled and maintained at ideal conditions for the snowgun requirements, and this will enable a range of snow types to be produced with a free fallen density from 0.3 tons per cubic meter to 0.08 tons per cubic meter. However, once the snow has fallen, the natural aging process begins so the snow must be conditioned to maintain the quality, reducing the need for producing fresh snow to a minimum. We form a low temperature “glacier” beneath the snow, this produces “constructive metamorphism” in the base of snow and causes new crystal re-growth, thus prevent-  ing ice formation even over many years of operation. There is never a need to melt the snow except for a small top layer which contains waxes from skis, dust, dirt and debris brought in on boots and clothing. Damage to the snow can occur at the main entry end exit areas as well as queuing areas, and this snow will be removed. It is also important to pay attention to keeping the lighting levels even and sources away from the surface.

Snow center guns have a unique design which enables the snow crystals to form within the first 25cm of flight from the nozzle. This is achieved by the size of particles produced, which form both nucleating (seed crystals) and free floating crystals which grow on the seed crystals. This reduces evaporation loss to a minimum. The snowguns are mounted on pan and tilt mechanisms that enable the area covered to be controlled to the operational requirements. Each gun is fitted with an automatic control valve which modulates the water flow and water to air ratio, enabling a wide range of snow types and densities to be produced. The guns are mounted at high levels and can operate independent of each other, this enables snow to be made in specific areas or over the complete complex. All of these operations are controlled by the main computer system.
Snow is not used up by the activities (skiing, tubing, etc) and will only be removed by any crystals adhering to the participants skis, boots and clothing etc. Thus, to maintain the snow layer thickness, fresh snow can only be added when old snow has been removed. This layer is removed with a grooming machine to a snow melt pit which incorporates a heat exchanger through which water is circulated across the melting snow. The waste snow contains valuable energy, i.e. the latent energy of the water, which can be reutilized by producing chilled water for air conditioning in other areas. Along with the water from the defrosting of the cooling coils, it is all cleaned through sand filters and purified with Ozone, and then reused either for snowmaking or for the evaporative condensers.  -Scott McGuffry

Operations Shots