Accent Refrigeration Systems Ltd.

The Global Energy Integration Experts

Energy Efficiency Products

An ice skating facility consumes a great deal of electrical energy during its normal operation. A typical community arena can consume between 600,000 and 2,000,000 kWh of electricity per year depending on the location, facility construction and operating profile. When you add demand charges and peak-load penalties to this, the costs can skyrocket. As a matter of fact, energy is the second-highest cost of operation, exceeded only by labor, in a typical ice facility.

The added pressures on global energy reserves as a result of instability in the Middle East combined with the industrialization of China and India will result in the cost of all energy sources to rise in the years ahead.

Through proper system design, steps can be taken now to reduce the amount of energy used in your facility. Following is a brief overview of a number of the more common energy-efficient features employed in the artificial ice industry. For a detailed explanation of these features or to hear about our recent unpublished green projects that are continuously being developed by our Enviro-Logic team, please contact our head office.

Efficient components alone do not translate into an energy-efficient facility. It is the proper integration and strategic management of components combined with operational procedures that will allow you to optimize your facility. We are experts in this field. Let us use our energy to help you save you energy.

Ammonia versus Freon

After all these years, ammonia is still the most energy-efficient refrigerant and is manufactured using natural elements (nitrogen and hydrogen). It has been used successfully and safely for well over 125 years and will not be phased out like R-22 and many of the new blends that have already come and gone. In addition, ammonia has no global warming potential. However, its toxic nature and pungent odor requires that more stringent code regulations be adopted in the design of the plant room. When using ammonia some jurisdictions require that a professional operator be on staff, which can increase the total facility operating cost. Larger multi-sheet facilities should strongly consider ammonia for its increased energy-efficiency advantage.

R-22 refrigerant is now in its final years, can no longer be put in new refrigeration systems and continues to rise in price monthly.. If you decide to use one of the new F-gas refrigerants, plant room and operator requirements are not as rigid as ammonia. Many of the new refrigerants are totally ozone friendly but have a very high global warming potential, which puts them on the environmental watch list.

Power Factor Correction

Power factor is the relationship (phase) of current and voltage in AC electrical distribution systems. Under ideal conditions, current and voltage are "in phase" and the power factor is 100%. If inductive loads, e.g. motors, are present, power factors less than 100%, typically in the range of 80% to 90% can occur.

Low power factor, electrically speaking, causes heavier current to flow in power distribution lines in order to deliver a given number of kilowatts to an electrical load.

Because the utility company must invest in oversized equipment to serve low power factor loads, a charge is commonly assessed on a facility's electric bill to recover the equipment costs and lost energy caused by low power factor.

Electric motors used to drive the refrigeration equipment commonly cause the voltage and current to get out of alignment. Power factor correction capacitors "realign" the voltage and current with each other. This is true with both fixed capacitors and automatic capacitor banks. These capacitors should be installed on all motors 25 hp and larger.

Power Factor Correction Bank

Computer Control System

The following are some of the many advantages of computer control. The computer system utilizes a technique known as floating suction. It will monitor the rate that the ice temperature is changing and select just enough compressor capacity to accomplish the required cooling task while maintaining consistent ice temperature. For every degree the suction pressure can be raised, the power can be reduced by approximately 1.5%. The computer can respond to any type of sensor including slab sensors, brine sensors, in ice sensors and infrared sensors.

The computer can be programmed to provide night setback to minimize running during unoccupied times, or in areas with off-peak loads the ice can be run down colder during periods with lower utility rates.

It is very cost effective to float the head pressure down during periods of colder ambient temperatures. Complicated formulas can be programmed into the computer to minimize the ratio of condenser fan to compressor horsepower. For every degree, the discharge temperature can be reduced by approximately 1%.

Premium-efficiency Motors

It is always important to use motors with a high efficiency rating. Although a premium efficiency compressor motor can cost as much as double the price of a standard high efficiency motor, the savings are easily calculated. Typically, the extra cost will range from $2500 to $5,000, but the savings over the lifetime of the motor will be $20,000 to $40,000. The added cost has a very healthy return on investment.

High Efficient Motor

Dual-drive Brine Pumps

Dual-drive brine pumps allow a 60% reduction in pump horsepower by stopping the large main brine pump and starting a lower horsepower pony pump. The reduced horsepower pony pump will still provide 60% to 75% of the pumping capacity of the main pump. Calculations must be run to determine the reduced flow capacity of the chiller and the level of staging offered by the compressors. In most cases a very favorable horsepower-per-ton improvement can be obtained. In addition to the energy savings, you will have the added security of a backup brine pump in the event of a failure.

Dual Drive Brine Pumps

Oversized Evaporative Condenser with Energy Miser Fan System

Evaporative condensers are the most efficient method of condensing. Consideration should be taken for local water conservation regulations, health regulations (Legionnaires Disease), and the mineral content of the water to ensure it is appropriate for your area.

It is always wise to select a condenser for the lowest condensing temperature that can be practically achieved. It is good design practice to size a condenser for a maximum of 85 F condensing at full load conditions. In areas with high power bills it can make economic sense to size for 80 F condensing temperature or lower if your outdoor ambient temperature will permit. For every degree you reduce the discharge temperature, the efficiency will increase by approximately 1%.

A dual-drive fan system will reduce the fan horsepower by 60% to 80% during reduced load conditions and during colder weather. This format will also provide a backup in the event of a fan motor failure.

A variable frequency drive (VFD) fan control will also provide excellent condenser efficiency. For optimum efficiency, a computer should control the VFD. The programming will factor in the condenser load profile, a refrigerant table and relative humidity.

Oversized Flooded Chiller

A properly engineered oversized chiller will provide several benefits to the system. The suction pressures can be operated at a higher level, increasing refrigeration system efficiencies by 1 1/2% for every degree the suction temperature is increased. Pressure drops will be substantially reduced on the brine side, minimizing pump horsepower and destructive velocities. The additional size will minimize the negative effects of scaling, further increasing the life of the chiller. The added surface area will facilitate rapid temperature pull-downs when required. A flooded chiller with low pressure drop requires less brine pump horsepower per ton of refrigeration.

Murray Chiller

Oversized Titanium Plate Chiller

Titanium plate chillers offer five major advantages:

  1. The optimum in corrosion resistance
  2. Herringbone counter-flow pattern enables excellent heat transfer at greatly reduced flow rates, thus minimizing the required brine pump horsepower
  3. Reduced floor space requirements
  4. An exceptionally reduced refrigerant charge of 35 pounds versus 1200 pounds for a conventional flooded chiller of the same capacity
  5. Ease of field service. An oversized plate chiller, which will reduce energy requirements as well as facilitate rapid temperature pull-down when required

Plate and frame exploded view

Liquid Refrigerant Sub-cooling / Snow Melt Pit

The entire electrical load in a refrigeration system is used to make ice, and then up to 10 times a day the ice is scraped off and allowed to melt. Many facilities use even more power by melting the snow with hot water. Traditionally, snow melt pits obtained the heat from high-temperature discharge gas. On a Freon system, a sub-cooling system will preserve the high-temperature discharge gas for heating hot water where it is more valuable. The liquid sub-cooling method melts the snow and recovers the cooling value of it, which in turn is directed back into the refrigeration system for a capacity boost of up to 30%. With a snow melt pit, the snow can be eliminated without opening the outside doors and letting the heat in. The refrigeration plant will run cooler and the refrigeration power costs will be reduced significantly during the ice melting process.

Sacramento Sub-Cooler

Hot Water Heat Reclaim

It is very economical to reclaim waste heat from the refrigeration plant for heating hot water. Hot water in arenas is typically used for the showers or for filling the ice resurfacer. This does not eliminate the need for a supplemental boiler but will drastically reduce the cost of operating it.

Desiccant Dehumidifier

One of the largest contributing factors of having a great ice surface is proper humidity control in the building envelope. Excess humidity also increases the refrigeration load on the ice plant. The most reliable and economical way of dealing with the humidity is through the use of a desiccant dehumidifier. This will provide you with an excellent ice surface during all weather conditions at a fraction of the operating cost of the old-style mechanical dehumidifiers.

Low-emissivity Ceiling

Up to 30% of the heat load entering a typical community arena is radiant heat generated from the sun's rays entering through the roof. A low-emissivity ceiling can block out up to 97% of this radiant heat, drastically reducing the load on the refrigeration plant. A low-e ceiling should be strongly considered for all recreational ice facilities.

Diesel or Gas-driven Compressors

In some locations, due to the availability or cost of electrical power, it may be favorable to operate one or all of the compressors with internal combustion engines. In areas with time-of-day billing, it can be advantageous to operate the engine during peak electrical demand periods. Additional heat reclaim is also available from the engine cooling system. Some gas companies offer significant grants for the conversion to gas. In deciding if this is a favorable option, you must calculate the additional cost of maintenance the engines will require.

Gass driven Vilter VSM501

Building Heating Integration

The whole refrigeration process involves moving heat from one area to another. In many arenas this heat is wasted at the condenser or used for inefficient purposes such as melting snow. It is very efficient to use this heat for heating the public areas throughout the complex or adjacent buildings. We have saved over a billion kilowatt-hours of energy by integrating ice rink refrigeration systems with building heating systems. We would be glad to design a system for your facility that will save you hundreds of thousands of dollars.

Arena heat gain chartThe chart (left) depicts the various sources of heat gain in a typical ice skating facility. The information is relative and will vary from place to place and season to season, but it offers a helpful visual indication of where energy consumption is prevalent and where energy saving measures should be emphasized.

For instance, it becomes obvious that installing a low-emissivity ceiling to reduce radiant heat load will provide far better value for your energy conservation dollars than insulating the headers if both energy conservation projects were of a similar value.

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