HOCKEY NIGHT IN CANADAThe Tim Hortons 4 Ice Centre located in Moncton, New Brunswick, Canada, is the city’s first multi-pad arena with four separate ice surfaces. Constructed in 2002, the facility was designed to incorporate a year-round arena facility as the focal point for community ice sports. Housing four National Hockey League-size ice rinks running 12 months of the year comes at the expense of substantial energy usage to maintain the desired ice conditions. A centralized ammonia refrigeration plant automated by a programmable logic controller- (PLC-) based control system was at the heart of the facility’s ice-making efforts.
Taking into consideration that the refrigeration system at the facility accounted for the largest usage of electricity, it was a natural decision to take the appropriate measures to enhance the efficiency of the refrigeration equipment. The Tim Hortons 4 Ice Centre needed an upgrade to its current PLC-based control system that could grow and accommodate the complicated usage schedules. Facility personnel contacted TechCold International (TCI), a division of Advanced Monitoring Technologies Inc. (AMT).
This automated control reduces runtime on these devices, saving energy and reducing associated greenhouse gas emissions. A user interface graphic is provided to allow facility personnel to set up event schedules and monitor how the system is running. By having the ability to monitor and control their system through the Pro-Act graphics, plant personnel can set the desired ice temperatures and schedule multiple events so that the control system can turn equipment on and off based on the system load requirements to maintain the desired ice temperatures.
Also, TCI looked to Portland, Maine-based Kepware Technologies for its communications software. Combining the technology afforded by Kepware’s KEPServerEX software and TCI’s ice rink control system, the facility was able to implement automated control over its refrigeration plant.
“Not only has KEPServerEX reduced the added investment required to establish communications on a project, with KEPServerEX, we install it, turn it on, and we know it will work,” said Brad Watts, director of refrigeration controls products.
SUPERMARKETS IN DENMARKTo date, most refrigerated display counters and freezer cabinets in supermarkets use fluorinated greenhouse gases as their refrigerants. However, in Europe there has been an increased use of natural refrigerants for supermarket refrigeration.
“Supermarket refrigeration can be environmentally friendly too,” said Monika Witt, CEO of eurammon, the European initiative for natural refrigerants. “For instance, the use of carbon dioxide makes for energy-efficient refrigeration plants and only makes a negligible contribution to the greenhouse effect. Besides, [carbon dioxide] CO2 is very cheap and available worldwide.”
In Denmark, the use of more than 10 kilograms of fluorinated gases (F-gases) in newly installed refrigeration systems has been prohibited by law since 2007. For this reason, the Danish supermarket chain Super Best opted for a CO2-based cascade system at its Copenhagen branch. So refrigeration specialists Knudsen Køling designed a refrigeration system that uses two refrigeration circuits linked by a plate heat exchanger. This allows three different temperature levels to be achieved, two of which are used for cooling and one for heat dissipation.
The first temperature level is needed in frozen food cabinets and the deep freeze chambers in the cellar. At an evaporating temperature of -28°C, the CO2 is used to maintain an ambient temperature of -20°.
The second temperature level is used for refrigerators and cold stores requiring an air temperature of a few degrees above 0°. This is achieved by supplying the evaporators with CO2 at an evaporating temperature of -10°. The third and highest level ensures reliable heat dissipation by condensation or gas cooling, depending on the ambient temperature. Overall, the cascade system has a refrigeration capacity of 150 kW.
Güntner components are used for the various temperature levels generated by the system and the cold stores are fitted with evaporators. The heat dissipation enables an evaporator to function as a gas cooler at elevated ambient temperatures and hypercritical processing. To guarantee the operational safety of the system, even at pressures of around 120 bar, Güntner used 0.7-mm-thick stainless steel for the gas cooler and the entire piping network. Thanks to its low-noise design, the gas cooler can be used in locations with very high noise-control requirements, e.g., residential areas. The injection to the evaporators and the cooling unit is controlled by Danfoss electrical components.
GROCERY STORE IN UNITED STATESWhen Safeway, the United States’ fourth-largest retail grocer, was searching for strategies to help reduce operating costs at its 1,767 stores nationwide, the Pleasanton, Calif.-based company turned to Carter Air Balance to investigate the efficiency of its stores’ HVAC systems.
According to Carter Air Balance Principal Vic Congi, as energy costs rise, more and more building owners are calling his company to find ways to make their buildings become more comfortable and operate more efficiently. Congi’s company is certified by the National Environmental Balancing Bureau (NEBB).
“NEBB-certified firms work with professional engineers and building owners to ensure that heating and cooling systems are designed, installed, and operating at peak efficiency,” he said. “We can also help owners of existing buildings reduce operating costs.”
Carter Air Balance began by conducting an air survey of a single store in Modesto, Calif. An audit of the store’s energy and airflow indicated that the store could cut costs by reducing the airflow required by 50 percent per square foot and installing new, high-efficiency motors in all the HVAC systems.
“The savings per store was $5,000 to $8,000 per year just for the HVAC systems in energy costs,” said Congi.
Safeway retained Congi and his firm to conduct reviews of 185 stores in Northern California and Hawaii.
“We installed high-efficiency motors in all of the stores over a 10-month period and have been working with Safeway ever since as they remodel or reconfigure existing stores, add new stores and retire older stores, saving them $950,000 annually,” said Congi.
Carter Air Balance visits each of the 185 stores approximately once every five years at a rate of about 37 stores per year, testing, adjusting, and balancing the HVAC equipment.