Artificial Ice Rinks

In 1876, Charles Dickens in a weekly magazine, described the first ice rink, considering copper pipe through which through it, a mixture of glycol and water circulated. At first glance it would seem that since then the concept has not evolved, however the tendency to save energy and protect the environment make other alternatives are developed using direct and indirect cooling systems.

Over time, the artificial ice rink industry has presented interesting variants in its designs. Therefore, it is necessary to keep in mind some basic concepts to understand how these surfaces are constructed.

By Eng. Ingrid Viñamata Chávez

In 1876, Charles Dickens in a weekly magazine, described the first ice rink, considering copper pipe through which through it, a mixture of glycol and water circulated. At first glance it would seem that since then the concept has not evolved, however the tendency to save energy and protect the environment make other alternatives are developed using direct and indirect cooling systems.

To understand how an ice rink is built, it is necessary to keep in mind some basic concepts, which must be taken into account such as temperature ranges, location, type, size, humidity, among others.

Ice is defined as the phase of water in the solid state. However, some other forms of substances, such as carbon dioxide, are also known as ice. The ice is colorless, transparent and crystallizes in the hexagonal system. Its melting point is 0°C; pure water also solidifies at 0°C, but ice will only form at 0°C if the water is cloudy or contaminated dissolved solids.

An important property of ice is that it expands as it solidifies. Here we identify another additional concept, because when expanding, it will generate efforts on the floor or base that contains it. At 0°C it has a relative density of 0.9168 compared to the density 0.9998 g/_cm3 of water at the same temperature. As a result, ice floats in the water.

Because water expands as it solidifies, an increase in pressure tends to transform the ice into water, and thus lowers the melting point of the ice. This effect is not very marked for ordinary pressure increases. For example, at 100 times normal atmospheric pressure, the melting point of ice is only 1°C lower than at normal pressure. At higher pressures, however, several allotropic or allotropic modifications of the ice (different forms of an element existing in the same physical state) are formed.

There are several types of ice:

Ordinary ice is Ice I. These allotropes are denser than water and their melting points increase with increasing pressure. At about 6,000 atmospheres, the melting point is again 0°C, and at a pressure of 20,000 atmospheres, the melting point rises above 80°C.

• Ice I (low temperature, cubic of centered facets, density approx. 0.9)

• Ice II (low temperature, orthrombic centered, density approx. 1.2)

• Ice III or Iii (low temperature, tetragonal, density approx. 1.1)

• Ice V (high pressure, low temperature, single-cylinder centered base, density approx. 1.2)

• Ice VI (high pressure, low temperature, tetragonal, density approx. 1.3)

• Ice VII (high temperature, high pressure, simple cubic, density approx. 1.7)

• Ice VIII (high pressure, tetragonal centered, density approx. 1.6)

• Ice IX (high pressure, tetragonal, density approx. 1.2)

• Ice XII (high pressure, low temperature, tetragonal, density approx. 1.3).

The crystalline form that ice takes as a function of pressure and temperature can be represented in the following phase diagram.

These solidification properties of water explain the way bodies of water freeze outdoors. When the surface temperature of an open-air body of water drops to the point of solidification, the surface water becomes much denser, and therefore will tend to sink, it is replaced by warmer water underneath.

Over time, the entire body of water reaches a uniform temperature of 4.0°C, the point at which water has its maximum density. If the water continues to cool, its density decreases, and ice ends up forming on the surface (see Figure 1).

Because of these density differences, the body of water solidifies from the top down. Giving rise to natural ice rinks, which form in lakes when ambient temperatures are below -10°C., the ice will typically remain between -4°C to -8°C.

Some other factors involved in the design of the tracks are humidity, ambient temperature and indoor temperature on closed tracks.

Humidity is defined as the content or percentage of liquid or water contained in the air. Relative humidity φ is defined as the ratio of the partial pressure of the vapour:

φ = real ρv at °T/ pv saturation at °T

The ratio of humidity ω is also known as absolute humidity and is the mass of steam per unit mass of dry gas:

ω = mv / mdg = ρv / ρdg

Some sources of moisture gain on permanent and/or closed tracks occur due to infiltration, when opening or closing doors, accesses, domes, and by spectators. This humidity, due to the difference in temperatures, can produce condensation, which is observed as when a glass or dome is fogged, sometimes small particles of water are formed that could drip and in some cases present stalagmites on the surface of the track.

Sometimes, the ice on the surface of the rink, acts as a dehumidifier, increasing the thermal load of the cooling equipment, which translates into high energy consumption, for these applications the use of mechanical dryers is recommended, which could be fixed or mobile (see figure 2)

1. Direct the air flow along the boards do not direct air over the ice surface.

2. Discherge duct equipped with horizontally and vertically adjustable louvers supplied by others.

3. DA2 units must be installed in pairs

4. Air inted must be a minimum of 4 feet from nearest obstruction.

5. Air discharge location must not be altered even when dry o tron units are located remotely and ductwork is used

View: Top view

Drawing No: DA2 inst

Scale: Not to scale

US and Canadian Patents

Date: Jan 07 1992

Approved:

DA2

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How to design an ice rink

Before designing a track, several factors must be considered:

1. Locate the track either mobile or fixed in places where you do not have to make a complicated foundation.

2. Preferably, it should be a flat surface.

3. Have drinking water and sufficient area to place the cooling equipment.

4. If it is a mobile track or for temporary events, it should be ensured that the ambient temperature is not very high or exposed to direct sunlight, as it would affect the surface of the track and therefore require more energy to keep the surface frozen.

5. They shall verify that they can have the electrical energy for the cooling, lighting, sound and pumping system. Or, rent a generation system suitable for the load demanded by the cooling system.

6. Define the size that will have, depending on the use, a track for jockey in the United States, must measure 26 m x 61 meters.

Design Fundamentals

This document is based on some of the recommendations and standards published by the American Society of Heating Refrigeration and Air Conditioning Engineers, Inc. (ASHRAE 1998).

Cooling requirements

In typical installations, a flat concrete base should be placed, with a vibration insulation, which can be sand or gravel, then a kind of pool with low height is built, where an exchanger is placed, which can be made of copper tubes with insulation, or of plastic material, with a diameter not exceeding 25mm, in addition to an ice sheet no larger than 40mm, in total it would be 65mm.

There are 2 key points when calculating cooling for an ice rink:

1. Water freezing condition at a certain time.

2. Calculate the amount of cooling needed to maintain the ice surface and temperature during the most critical condition of ambient temperature, spectators and users.

Considerations:

1. The thermal load needed to make the ice is calculated, the amount of ice required (surface multiplied by the thickness of the ice).

2. The water is reduced from an application of 0°C to start the transformation of water into ice.

3. Ice is reduced, up to the required temperature and

4. Manually, thermal losses and losses during freezing are calculated.

To calculate the amount of cooling required of a track of 1,500 m², with a thickness of 25 mm in 24 hrs. Assuming the materials according to the following:

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The latent heat of ice water is 334 KJ

Thermal loads of the building and pumping equals 170 KW of cooling

System losses 15%

Body of water = 1500m2 x 0.025m x 1000 kg/m3 = 37,000 Kg

Concrete mass = 1500m2 x 0.15m x 2400 kg/m3 = 540,000 Kg

Then:

QR = (System Losses) (QF + QC + QSR + QHL)

From where:

QR = Cooling required

QF = Chilled and frozen water

QC = Concrete load to be cooled

QSR = Refrigeration of antifreeze (Glycol)

QHL = Load generated by pumping and building

QR = 37,500 kg ‹4.18(11-0) + 334 Kj/Kg + 2.04 (0 – (-4))›/(24 hr x 3600 s/h) = 168.5 Kw

QC = 540,000 x 0.67 (2-(-6))/(24 x 3,600)= 33.5 kW

QSR = 14,000 x 3.5(5 –(-9))/(24 x 3,600) = 7.9 kW

QR = 1.15(168.5 + 33.5 + 7.9 + 170) = 437 kW.

Once the cooling equipment is selected, the cooling water plant is selected and designed. (See Figure 3)

The cooling coil and/or exchanger is selected and calculated for the required thermal load and to evenly distribute the load along the track, in order to form a flat, uniform and resistant surface.

The coil can be made of materials such as polycarbonate, with copper tubes and plastic insulation, etc.

The ice water system can be by reverse return or by two pipes. Tubes normally operate at working pressures of 280 to 350 KPa. Ice on the surface should be kept at -4°C constant.

Finally, for the construction of the floor, during the calculation, we consider the thermal losses from the concrete. However, there are five types of flooring that we could find in the design:

1. Open, suitable for metal or plastic tubes, the ice is manufactured directly on the tubes, ideal for mobile tracks.

2. Permanent, where the tubes are embedded or inside the concrete.

3. Permanent with concrete base and insulation, to reduce thermal gain per floor, in addition to having the tubes inside the concrete.

4. Permanent insulated, with a concrete base armed with solids or compost, vibration insulation system and thermal gain.

5. Insulated base with preheating. This type of soil is recommended for tracks where there is high humidity, or moisture and condenser could have problems, especially after operating for more than 6 months.

Recommendations for energy saving:

1. Select the right cooling system for each application.

2. Once the ice has been produced, for no reason should it melt daily, preferably the surface should be kept at -4°C constant.

3. Install the track in perfectly conditioned places, where solar radiation or gain by roof, glass, dome or others, do not generate high thermal load. (see Photo 1)

4. Use liquid exchangers for the manufacture of high energy efficiency tracks, such as the Calmac IceMat ® type

5. Use high efficiency liquid coolers, which are of reliable manufacture for applications on ice rinks. It is also recommended to use only the recommended percentage of glycol or antifreeze, which goes according to the desired liquid temperature, for ice production and maintenance (see Photograph 2 or Environment section in this same publication).

6. Place energy control and monitoring system for the optimization and operation of equipment, events, scheduling and maintenance. One recommendation may be the Tracer Summit Trane Energy Services.

7. Use a high efficiency lighting, cold type, which is recommended can be integrated into the control system in order to schedule events and schedules easily. If you opt for this type of system, the Tracer Summit Lighting Integration is suggested.

8. In auditoriums, stadiums, shopping or convention centers, and other enclosed spaces, humidity and indoor temperature must be maintained to avoid gaining sensitive and latent heat in the ice.

9. It is also recommended to place variable frequency drives in the pumping to optimize the operation at partial loads.

10. For ice formation, demineralized water or water with few minerals should be used. This will improve the quality of the ice, as well as its color, and will decrease its insulating capacity.

Authors:

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