Refrigeration – Processes – Congealing flowable material – e.g. – ice making
Patent
1987-02-03
1988-12-27
Tanner, Harry B.
Refrigeration
Processes
Congealing flowable material, e.g., ice making
62347, 239 22, F25C 304
Patent
active
047931426
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to a method for making artificial snow, and to a snow skiing slope using such snow.
(2) Prior Art
In certain skiing resorts, man-made slopes are created using snow-machines which spray water and compressed air in a careful-y controlled atmosphere (for both temperature and humidity) to create a blanket of snow. These machines are expensive to operate and the atmosphere is difficult to control, requiring expensive air conditioning equipment. The man-made slopes generally only extend the operating life of the slope by approximately 30 days.
In more temperate areas, artificial slopes are created using mats or mat-like layers of e.g. "Dendex", "Delta" or "Dri Sno" (trade marks) materials. These slopes require the use of special skis and poles and cannot truly re-create a snow-covered slope.
In International Application No. PCT/AU85/00267 (Bucceri) there is disclosed a method for making artificial snow by mixing water with a water swellable polymer to approximately 50-70% of the maximum water retention capacity of the polymer, aerating the mixture and freezing the mixture to produce snow crystals which can be laid on a refrigerated floor to form a skiing slope. This method has proved very effective but in certain applications the cost of the polymer is a disadvantage.
SUMMARY OF THE PRESENT INVENTION
It is an object of the present invention to provide a method of making artificial snow which is relatively simple and inexpensive.
It is a preferred object to provide a method where the snow can be laid in layers e.g. of different crystal size or where a layer of "powder snow" can be laid over a harder base snow.
It is a further preferred object to provide a method where the water can be recovered, and the snow refrozen, as required.
It is a still further preferred object to provide a ski-slope incorporating the snow produced by the present invention.
Other preferred objects of the present invention will become apparent from the following description.
In a broad aspect the present invention resides in a method for making artificial snow including the steps of:
mixing water with a surfactant (i.e. surface-active-agent or wetting agent);
agitating, aerating and/or bubbling gas through the mixture to form a foam or froth of water bubbles;
applying the foam or froth of bubbles to the area on which the artificial snow is to be created; and
freeze the foam or froth of bubbles to form the snow crystals.
Suitable surfactants include soaps and detergents; sulphated, aliphatic or aromatic alcohols; linear or branched chain alkybenzene sulphonates; alkyarine sulphonates; sodium dodecylbenzene sulphonate; alkyl sulphonates; anionic, cationic and non-ionic surfactants.
Non-ionic surfactants are preferred as these form a resilient foam with small/minute bubbles which on freezing, produce high quality snow crystals down to powder snow size. Preferably the surfactant forming 0.03% to 5% of the mixture by weight. For environmental reasons, bio-degradable surfactants are preferred.
A bulk volume of the mixture may be agitated or aerated to produce a foam of bubbles on top of the mixture and the foam may be transferred or transported to the area where the snow is to be created. The mixture may be aerated by pumping air through the mixture at the ratio water:air 1:1 to 1:5 (v/v), the preferred aeration range being 1:2 to 1:3 (v/v).
Alternatively, the mixture may be mixed and sprayed from equipment of the type used for fire fighting foam (i.e. a foam generator), the foam of bubbles being sprayed over the area where the snow is to be created.
The foam may be laid over a skiing slope and frozen by the cold ambient air or may be laid over an area covered by a flexible cover or structure into which is pumped cold air or refrigerant. The foam may also be laid over artificial snow formed by the method of International Application No. PCT/AU85/00267 to form a layer of powder snow. Preferably the foam is laid over a refrigerated grid so that the bubbles break down
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Permasnow (Australasia) Limited
Tanner Harry B.
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