U.S. patent application number 12/306187 was filed with the patent office on 2009-12-10 for method for the production of an ice surface for ice rinks.
This patent application is currently assigned to Unversitat Innsbruck. Invention is credited to Thomas Loerting.
Application Number | 20090301105 12/306187 |
Document ID | / |
Family ID | 38458288 |
Filed Date | 2009-12-10 |
United States Patent
Application |
20090301105 |
Kind Code |
A1 |
Loerting; Thomas |
December 10, 2009 |
METHOD FOR THE PRODUCTION OF AN ICE SURFACE FOR ICE RINKS
Abstract
A method for producing an ice surface for an ice rink by
freezing water to which an inorganic substance is added is
characterized in that the inorganic substance is ammonia, an alkali
hydroxide or alkaline earth hydroxide, a hydrogen halide, nitric
acid, sulfuric acid, phosphoric acid, an alkali salt, alkaline
earth salt or ammonium salt of said acids, or ammonium-bicarbonate,
or a mixture of several of said substances.
Inventors: |
Loerting; Thomas; (Rum,
AT) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Unversitat Innsbruck
Innsbruck
AT
|
Family ID: |
38458288 |
Appl. No.: |
12/306187 |
Filed: |
June 19, 2007 |
PCT Filed: |
June 19, 2007 |
PCT NO: |
PCT/AT07/00298 |
371 Date: |
January 26, 2009 |
Current U.S.
Class: |
62/66 |
Current CPC
Class: |
C09K 3/24 20130101 |
Class at
Publication: |
62/66 |
International
Class: |
F25C 1/00 20060101
F25C001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2006 |
AT |
A1067/2006 |
Claims
1. Method for the production of a homogeneous ice layer for an ice
rink by means of freezing water to which an inorganic substance is
added, characterized in that the substance added to the water is an
alkali hydroxide or alkaline earth hydroxide, a hydrogen halide,
nitric acid, sulfuric acid, phosphoric acid, an alkali salt or
alkaline earth salt of said acids or a mixture of several of said
substances.
2. Method for the production of hard ice for an ice rink, wherein
water is applied to the cooled area of the ice rink, characterized
in that ammonia is added to the water before freezing.
3. Method according to claim 1, characterized in that
preferentially HF, HCl, HBr, HI, LiOH, NaOH, KOH, Ca(OH).sub.2 or
mixtures of several of these substances are added to the water.
4. Method according to any of claims 1 to 3, characterized in that
the substance added to the water is added in a concentration of up
to 5 ppm.
5. Method according to claim 1, characterized in that the maximum
concentration of the substance added to the water does not exceed
20 ppm.
6. Method according to claim 1, characterized in that the substance
added to the water is added by admixing to the water before
freezing in the form of dilute solutions.
7. Method according to claim 1, characterized in that the substance
added to the water is added by treating the ice after freezing with
a liquid which contains the additives.
Description
[0001] The invention starts out from a method for the production of
an ice surface for an ice rink in accordance with the preamble of
claim 1.
[0002] The ice quality of an ice rink plays a central role
particularly for speed competitions, e.g., speed skating. The
mechanical properties of the ice, correspondingly, of the ice
surface of the ice rinks, can be controlled via various parameters,
e.g. via the ice temperature, the relative atmospheric humidity or
the conductivity of the water forming the ice.
[0003] Various methods for improving the ice quality are known so
far. Mechanical unevenness or contaminations in the ice are
flattened or removed by ice resurfacing machines. In order to
control air temperature and humidity, ice rinks are installed in
ice pavilions. It is furthermore known to remove bothersome sodium
and calcium ions from the ice by means of desalination and
decalcification using an osmosis system. Also known is the use of
de-ionized water instead of mineral-containing tap water during ice
preparation for minimizing the friction caused by the ions in the
water.
[0004] Also the addition of various organic or inorganic substances
to the water before the freezing process is known. For example,
from the patent document DE 526 224 it arises that the surface area
to be iced is covered with a salt mixture of sodium carbonate and
sodium sulphate, which is admixed with water until the salt reaches
a state of maximum content of water of crystallization, and the
mixture is frozen thereafter.
[0005] Disadvantages related to the known methods of improving ice
quality, particularly to the methods of osmosis and
demineralization, are the high costs of installation and
maintenance.
[0006] Thus it is the object of the invention to disclose a
cost-efficient method for improving the quality of ice for ice
rinks.
[0007] This object is achieved by means of the characterizing
features of claim I together with the category-forming
features.
[0008] According to the present invention it is provided that a
substance is admixed to the ice-forming water, said substance being
ammonia, an alkali hydroxide or alkaline earth hydroxide, a
hydrogen halide, nitric acid, sulfuric acid, phosphoric acid, an
alkali salt, alkaline earth salt or ammonium salt of said acids, or
ammonium-bicarbonate, or a mixture of several of said
substances.
[0009] Thereby it is feasible to accelerate or to retard the
freezing process, to obtain selectively a hard or soft, a
mechanically resistant, a highly slippery or rather sticky ice
surface, which can be prepared and maintained in a simple manner on
existing ice rinks using conventional equipment for preparing the
ice surface without the need of costly installations or of
subsequent installation of expensive equipment.
[0010] Further advantageous features and embodiments are evident
from the dependent claims.
[0011] Advantageously, NH.sub.3, HF, HCl, HBr, HI, NH.sub.4I,
NH.sub.4F, NH.sub.4Br, LiOH, NaOH, KOH, Ca(OH).sub.2 or a mixture
of several of these substances are added to the water
preferentially, since said substances, due to their
physical-chemical properties, cause the strongest effect of all
possible dopants.
[0012] Furthermore it is advantageous that the substance added to
the water is added in a concentration of up to 5 ppm, which
requires only small amounts of dopants and is thus
cost-efficient.
[0013] It is advantageous, furthermore, that the maximum
concentration of the substance added to the water does not exceed
20 ppm, since thereby an environment-friendly and--with respect to
contamination by possibly noxious substances--safe concentration is
ensured.
[0014] It is advantageous that the substance added to the water can
be added by admixing to the water before freezing in the form of
dilute solutions so that a homogeneous ice layer can be
generated.
[0015] It is also notably advantageous that the substance added to
the water can be added after freezing by treating the ice with a
liquid which contains the additives because thereby also an ice
surface which was prepared using un-doped water can be improved in
terms of quality afterwards during post-processing of the ice
surface, without the need of freezing a new ice surface from
scratch.
[0016] For the preparation of ice for speed competitions such as
for example speed skating, it is desirable to reduce the
coefficient of friction of the ice surface. Up to now, mainly an
optimization of factors in the surroundings of the sportspersons
has been carried out, e.g. the athlete's clothing (thin,
aerodynamic skins as a suit or long, thin blades on the skates) or
a reduction of the air drag by relocating the ice rinks into sports
halls or to high altitudes. As recently as in the past 10 years one
has begun to consider also the ice itself in order to achieve an
improvement of the surface of the ice and therewith increased
velocities.
[0017] The fact that a quasi-liquid layer on the ice causes its
known properties (slippery, etc.) has been known since Faraday in
1850. The dependence of the thickness of this thin water film on
temperature is the result of various studies performed within the
last 50 years. Below approx. -25.degree. C. this water film
disappears, and the ice becomes "sticky" (tongue sticks to ice,
etc.). The novelty of the present invention consists in that the
layer thickness and therefore the properties of the ice can be
governed towards the desired direction, for instance towards a
lower coefficient of sliding friction, at any arbitrary ice
temperature by means of specific addition of admixtures at trace
concentrations.
[0018] The method according to the present invention thereby
proposes for the production of ice by freezing of de-ionized water,
to add admixtures purposefully to said water, i.e. to dope the
water. This brings about that properties such as the static as well
as the dynamic coefficient of friction or the surface hardness can
be selectively controlled by these additives. The additive can
either be added by admixing it to the water (before freezing) in
the form of dilute solutions or by treating the ice (after
freezing) with a liquid which contains the admixtures. An adaption
of currently used ice preparation machines is not necessary, since
instead of water simply contaminated water, e.g., de-ionized water,
tap water, distilled water, etc. can be used.
[0019] In the following the method according to the invention is
illustrated on the basis of the execution of the method using a
preferred admixture.
[0020] As an example, the doping of water with 4 ppm NH.sub.3 is
described here. In order to prepare an ice surface of 200 m.sup.2
and 5 cm thickness, 10000 litres of water are needed. These are
typically sprinkled onto a pre-cooled area using a hose, which is
connected to the water pipe. A uniform doping with NH.sub.3 can
e.g. be achieved by interconnecting a metering valve which doses a
dilute NH.sub.3 solution into the tap water in dependence on the
rate of flow. One e.g. provides one litre of a 4% solution of
NH.sub.3, which is supposed to be dosed into the water. At a flow
rate of 50 litres per minute the metering valve is supposed to dose
in 5 millilitres per minute for a duration of 200 minutes. This
results in a dilution of 1:10000 so that the tap water finally
contains 4 ppm NH.sub.3.
[0021] Now the ice needs to be given the time to freeze
homogeneously on the pre-cooled surface. For this purpose the
protocols can be employed which are used by ice preparation
specialists today. The more time the ice is given, i.e., the slower
the cooling rates, the larger the crystals and the smoother the ice
surface. If one cools faster, then smaller crystals result which
abut upon each other and produce interfaces ("triple junctions" or
"grain boundaries", respectively)--the ice surface becomes
rough.
[0022] The method is also suitable for a surface treatment of the
ice using special ice preparation machines. These machines, which
are for instance employed during the breaks in ice hockey matches,
mostly have a water tank and a snow container. These machines
collect abraded snow, fine down the topmost ice layer and apply a
new layer of water onto the ice. If one mixes an appropriate amount
of NH.sub.3 also into the water tank of the machine, then
previously un-doped ice benefits for the first time from the
surface properties improved by the doping, or, correspondingly, in
case of ice which has already been prepared by means of doping, the
optimized properties of the doped ice persist even after repeated
ice preparation.
[0023] By the selection of the dopant or alternatively of the
dopant mixture and of the mixing ratios various ice properties can
be optimized:
[0024] For example, 3 ppm HF bring about a considerable increase in
the ice flow properties. An ice-skater "cuts" into the ice with his
blade and thereby displaces ice from the groove, which normally
ends up as "snow" on the ice surface. In the case of doping with 3
ppm HF, the displaced ice flows back into the (just produced)
groove to a much greater extent so that firstly less "snow" comes
to lie on the ice surface and secondly the degree of destruction of
the ice surface is minimized. In parallel with this, the ice
surface also becomes softer. Using 3 ppm NH.sub.3 instead, the
opposite effect occurs, attrition is enforced, the ice surface gets
destroyed more severely and also becomes harder.
[0025] If one needs a very hard ice surface (e.g., for ice hockey
matches), then NH.sub.3 doped ice has a decisive advantage: Today,
ice preparation specialists adjust the ice hardness via the
temperature. Soft ice surfaces (e.g. for figure skaters) are
produced by making "warm" ice (e.g., at -3.degree. C.), while hard
ice surfaces require cooling to e.g. -10.degree. C., thereby
consuming much energy. Using NH.sub.3 doped ice one can produce
harder ice already at higher temperatures in an energy-saving
manner.
[0026] For organizers of major speed skating events it is
furthermore of great importance that national and continental or
even Olympic and world records are run on their tracks. Ice from
which one can push off better and on which one glides better, is
very important here. The method according to the invention is also
suitable for controlling the coefficient of sliding friction. For
instance it can be measured that a certain doping results in a
water film even on an ice surface at -80.degree. C., which reduces
dynamic friction. On un-doped ice this water film disappears
already below approx. -25.degree. C. so that cryogenic ice is no
longer slippery. It is also conceivable that a dopant is found
which increases dynamic friction on ice strongly by suppressing the
water film already at comparably high temperatures.
[0027] Good ice surfaces are prepared over a period of several
days, since this is the time needed to extract the thermal energy
from the water molecules, to produce crystallization nuclei and to
achieve optimum crystal growth. Doping with a suitable additive can
accelerate all three of these processes and, therefore, can reduce
time and costs for producing an ice surface.
[0028] The investigated substances are built directly into the ice
lattice up to concentrations of 5 ppm and change the microscopic
properties such as relaxation times, H-transfer times, electric
conductivity, etc. via the production of so-called D- or L-defects.
This leads to a change of the macroscopic properties. Other
substances such as for example bigger inorganic molecules, organic
molecules, etc. are not built into the crystal lattice, but merely
into lattice voids or grain boundaries, in many cases they are even
only discharged via the surface and, accordingly, do not alter the
microscopic and macroscopic properties of ice.
[0029] The list of substances that are capable of being built into
the crystal lattice and which are therefore suitable for doping
comprises ammonia, alkali hydroxides and alkaline earth hydroxides,
hydrogen halides, nitric acid, sulfuric acid, phosphoric acid,
alkali salts, alkaline earth salts and ammonium salts of said
acids, and ammonium-bicarbonate. Particularly preferred are thereby
NH.sub.3 (ammonia), HF, HCl, HBr, HI, NH.sub.4I, NH.sub.4F,
NH.sub.4Br, LiOH, NaOH, KOH, Ca(OH).sub.2 or mixtures thereof,
which have the highest potential and the maximum effect,
respectively.
[0030] The range of concentrations which has to be covered results
from the concentration of molecules directly (substitutionally)
incorporated into the lattice plus from the minerals already
present in the tap water. The threshold for fluorides, for example,
amounts to 1.5 ppm so that for a hard NH.sub.3-doped ice surface
the softening effect of fluorides has to be compensated at first.
The maximum of 1.5 ppm for compensation plus 5 ppm which are
substitutionally incorporated at the utmost result in a threshold
of 6.5 ppm for doping the tap water. Including a safety margin, the
maximum concentration which has an influence on the macroscopic ice
properties is 20 ppm.
[0031] An equivalent amount of the proposed substances is also
found in rainwater so that toxicity has not to be assumed. After
thawing the ice surface, the disposal of the water containing the
additives can be carried out in a simple and cost-effective manner
via the canalization.
* * * * *