WO1998006988A1

WO1998006988A1 - Method and apparatus for making snow

Info

Publication number: WO1998006988A1
Application number: PCT/AU1997/000490
Authority: WO
Inventors: Herman Arnolt August Eden
Original assignee: SNOW FUN FACTORY Pty Ltd
Current assignee: SNOW FUN FACTORY Pty Ltd
Priority date: 1996-08-09
Filing date: 1997-08-04
Publication date: 1998-02-19
Anticipated expiration: 1999-02-09
Also published as: AUPO153396A0

Abstract

A snow making apparatus comprises a plurality of hollow disc like rotatable evaporators (1) through which a refrigerant medium circulates via a hollow shaft (7). Atomising nozzles (6) attached to spray bars (3, 4, 5) direct a fine atomised mist of water towards the surface of the disc (1). Snow crystals are grown by the sequential application of atomised water mist over previously formed crystals and are removed from the disc (1) by a plastics scraper blade (2).

Description

TITLE METHOD AND APPARATUS FOR MAKING SNOW

FIELD OF THE INVENTION This invention is concerned with a method and apparatus for artificially making "real" snow as distinct from artificial snow.

BACKGROUND OF THE INVENTION In the past there have been many proposals for apparatus and methods for making artificial snow as well as apparatus and methods for artificially making snow.

Exemplary of methods for making artificial snow and International

Patent Applications PCT/AU85/00267 which deal with frozen water absorbent polymeric granules and PCT/AU 86/00158 which deals with the freezing and subsequent crushing of a foam produced from an aqueous mixture containing a surfactant.

While generally effective for their respective purposes, these processes do not produce a fine dry crystalline product approaching the feel and texture of real or material snow. Other well known processes for artificially producing "real" snow are also well known. Generally such processes involve directing an atomised spray of water through a specially designed nozzle into an air mass of sub-zero temperature to cause formation of ice crystals approximating "real" snow. While all of the above prior art processes, in suitable environments are satisfactory for their respective purposes, the economics thereof do not lend themselves to commercially viable operations such as indoor or outdoor ski fields.

SUMMARY OF THE INVENTION It is an aim of the present invention to overcome or alleviate at least some of the prior art problems and to produce artificially a snow-like product having the feel and texture of a "real" snow.

According to one aspect of the invention there is provided a method of producing a snow like product, said method comprising the steps of:- spraying on to the surface of a rotatable refrigerant evaporator a fine mist of water whereby in use, the operational parameters of said evaporator are such as to accumulate a layer of individual ice crystals; and, removing accumulated ice crystals from said rotatable evaporator by one or more mechanical scrapers.

If required the rotatable evaporator may comprise a rotating cylindrical drum through which refrigerant medium is circulated.

Suitably the rotatable evaporator comprises a rotating disc through which refrigerant medium is circulated. Preferably the rotatable evaporator comprises a plurality of rotatable discs.

The water being sprayed as a fine mist may include a surfactant or other surface tension modifier to selectively alter the shape and size of ice crystals formed on the surface of the evaporator. Suitably the water to be sprayed on to the rotatable evaporator is applied as an atomised mist over a preselected region or regions of said rotatable evaporator.

According to another aspect of the invention there is provided an apparatus for performing the first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be more readily understood an put into practice, reference will now be made to the accompanying drawings in which:- FIG 1 illustrates a schematic cross section of a rotatable disc evaporator. DETAILED DESCRIPTION OF THE DRAWINGS FIG 1 illustrates a rotatable evaporator of the type employed in United States Patents No. 5157939 and No. 5363659 to Heat and Control Pty Ltd. These patents relate to methods and apparatus for producing flake ice for packaging of frozen foods and the like.

Both of these United States patents describe a rotatable disc like member having a labyrinthine array of refrigerant channels disposed between opposed smooth faces.

The disc rotates partially submerged in a container of water extending between 0° and 180° from a scraper blade or otherwise has a spray of water in the form of coarse droplets directed on to the disc at about 90° from the scraper blade, both in the direction of rotation of the disc. The water is sprayed onto the disc to form a continuous film on the disc surface but in the embodiment described in these patent specifications, only 90° of rotation is provided before the sheet ice so formed is removed by the harvesting blades.

Depending upon such operational parameters as disc rotation rate, refrigerant temperature, water temperature, ambient air temperature or water application rate, a contiguous thin layer of sheet ice of from about 1 mm to about 4mm will be formed.

The layer of sheet ice is removed from the rotatable drum by scraper blades which fracture the ice sheet to facilitate removal.

The present invention preferably employs a single or multi disc apparatus of the type described in United States Patents 5157939 or 5363659 with suitable modifications to permit the method of the invention to be practised.

As shown schematically in FIG 1 , the rotatable disc 1 has a scraper blade 2 positioned at about 90° from the vertical in the direction of rotation of the disc as shown by the arrow. A plurality of atomizing nozzles 6 are fitted to spray bars 3, 4 and 5 are provided in the quadrants 90°-180°, 180°-270° and 270°-360° relative to a vertical line extending from the rotational axis of the disc.

Refrigerant medium from a refrigerating plant (not shown) circulates throughout the hollow interior of disc 1 via hollow shaft 7 upon which disc 1 rotates. Atomised water particles contacting the disc in the 90°-180° quadrant form a thin layer of discrete individual crystals on the surface of disc 1 , the crystals growing in a direction normal to the disc surface. The snow crystals initially formed have a configuration in the form of a six pointed star similar to "real" snowflakes. As further atomised water is added to the crystals they form feathery or needle like crystals which adhere to form very small snow "flakes" - again similar to natural snow.

As the initial layer of ice crystals passes through the 180°-270° and 270°-360° quadrants, atomised water contacting the layer of crystals causes a continuing controlled growth in the crystal sizes, again in a direction normal to the disc surface.

As the initial layer of ice crystals passes through the 180°-270° and 270°-360° quadrants, atomised water contacting the layer of crystals causes a continuing controlled growth in the crystal sizes, again in a direction normal to the disc surface. Depending upon the operational parameters of the apparatus such as water droplet size, water temperature, spray rate, disc rotation rate and temperature of the refrigerant, the layer of crystals may be controlled to emulate fine dry powder snow, rime or hoar frost in a layer of from 1mm to about 6mm in thickness which is easily removed from the disc by scraper blades 2.

As the ice crystals formed on the surface of the disc are not adhered as a single mass, the degree of adhesion to the disc surface is minimal compared to a contiguous sheet of ice as formed in the flake ice operation. In the manufacture of flake ice, hardened and sharpened steel blades are spaced at a predetermined distance from the disc surface to avoid frictional contact therewith. The snow layer, being quite soft, is easily removed from the disc surface by a hard plastics blade such as nylon or the like which may be placed in direct contact with the disc surface without fear of damage either to the blade or the disc surface. Snow crystals removed from the disc surface are collected in a hopper or the like for subsequent removal by a screw auger or compressed air conveyor to a selected site such as the surface of an indoor ski slope.

It has been noted that the incorporation of a small quantity of surfactant in the range 10 ppm to 250 ppm in the atomised water spray can substantially affect the "feel" of the snow so produced. The crystal size tends to be much finer and the snow has a softer feel not unlike fresh dry powder snow.

Any commonly available surfactant having ionic, non-ionic or amphoteric properties may be employed. Such surfactants may be typically selected from alkyl sulphates, alkyl-aryl sulphonates, polyethylene axide derivatives or the like.

While the mechanism of the surfactant on snow "feel" as not fully understood, it is believed that a reduction in the surface tension of the feed water effects a control on the growth of individual crystal sizes.

Suitable controls in the form of programmable logic controllers (not shown) provide control over all operational parameters for the evaporator disc and atomising sprays to selectively produce a snow product of a desired consistency and at a predetermined production rate. As generally the rate of rotation of the evaporator disk is greater than the rotation rate employed in the manufacture of flake ice for which the apparatus was designed, an equivalent output of about 2 tonnes/24hrs of snow are produced from each 600mm diameter disc.

The rotatable disc evaporator is connected to a conventional compressor/condenser unit of 8-10 kilowatts of refrigeration capacity for each rotatable disc. The rate of production of snow can be regulated by water temperature , water spray rate, disc rotation rate, refrigerant type, and the suction temperature of the refrigerant which typically may be in the range - 10°C to -25°C, preferably in the range -10°C and -15°C.

It will be readily apparent to a skilled addressee that many modifications and variations may be made to the invention with out departing from the spirit and scope thereof.

Claims

1. A method of producing a snow like product, said method comprising the steps of spraying on to the surface of a rotatable refrigerant evaporator a 5 fine mist of water whereby in use, the operational parameters of said evaporator are such as to accumulate a layer of individual ice crystals; and, removing accumulated ice crystals from said rotatable evaporator by one or more mechanical scrapers. 0

2. A method as claimed in claim 1 wherein the rotatable evaporator comprises a rotating cylindrical drum through which refrigerant medium is circulated.

3. A method as claimed in claim 1 wherein the rotatable evaporator comprises a rotating disc through which refrigerant medium is circulated. 5

4. A method as claimed in claim 3 wherein the rotatable evaporator comprises a plurality of rotatable discs.

5. A method as claimed in any preceding claim wherein the water being sprayed as a fine mist includes a surfactant or other surface tension modifier to selectively alter the shape and size of ice crystals formed on o the surface of the evaporator.

6. A method as claimed in any preceding claim wherein the water to be sprayed on to the rotatable evaporator is applied as an atomised mist over a preselected region or regions of said rotatable evaporator.

7. A method as claimed in claim 6 wherein water is sprayed as an 5 atomised mist sequentially over said preselected region or regions of said rotatable evaporator.

8. A method as claimed in claim 6 wherein water is sprayed as an atomised mist continuously over said preselected region or regions of said rotatable evaporator. 0

9. An apparatus for producing a snow like product according to the method of any preceding claim, said apparatus including spray bars with spaced atomising nozzles adapted to spray an atomised mist of water over a preselected region or regions of said rotatable evaporator.

10. An apparatus according to claim 9 wherein the atomised mist is sprayed over said preselected region or regions of said rotatable evaporator through between 180° to 270° of rotation.

11. An apparatus as claimed in claim 9 or claim 10 including a resilient scraper bar.

12. An apparatus according to claim 11 wherein the scraper bar comprises a plastics material.

13. An apparatus according to any one of claims 9 to 12 including a programmable logic controller to control operational parameters of said apparatus.