Cold and Wet Uses for Ammonia
Lent Park in Cologne, Germany, has an elevated ice track, a lower level ice rink, and an indoor swimming pool.
Europe’s only 260-meter-long (close to 300-yard) elevated ice track runs around the building as a gallery on the first floor, offering skaters views of the lower 1,800 m² (close to 6,000 square feet) ice rink, the swimming pool, and a restaurant.
Gesellschaft für Kältetechnik-Klimatechnik mbH (GfKK mbH) designed the elevated ice track and the ice rink as a direct evaporation system with ammonia as the refrigerant. A central refrigeration plant was installed with total refrigeration capacity of 819 kW and a refrigerant charge of 7,000 kg NH3.
According to the Eurammon, a joint initiative of companies, institutions, and individuals who advocate natural refrigerants, “The system operates with three GEA Grasso reciprocating compressors. The waste heat is put to energy-efficient use for heating process water and melting the snow pits, as well as antifreeze protection. The remaining waste heat is emitted to the outside with an air-cooled condenser that operates with EC ventilators. Refrigeration supply for the elevated ice track is designed to maintain a constant ice quality even under differing framework conditions and heat loads. The plant itself is equipped with a central GfKK control unit with visualization.”
The Ozeaneum in Stralsund, Germany, is a museum with seawater aquariums, the largest of which encompasses 2.6 million liters (close to 700,000 gallons) of water. Altogether the Ozeaneum’s aquariums contain 6 million liters (1.6 million gallons) of water.
According to SWS-Energie GmbH, a subsidiary of Stralsund municipal utilities and the individuals responsible for the project, Johnson Controls Systems & Service GmbH was contracted to draw up the concept and do the installation “as a sustainable energy-efficient refrigeration plant. The system was to avoid plumes of steam caused by evaporation as far as possible, while reducing noise to a minimum level.”
The museum required refrigeration capacity of 900 kW, with 400 kW for the aquarium systems and 500 kW to air condition the building.
Again, according to comments from Eurammon, “Refrigeration is provided by cold water at a flow temperature of 6˚C (43˚F) and a return temperature of 12˚C (54˚F). A single-stage ammonia refrigeration system with flooded evaporation was used. The system consists of two separate Chill-Pac chillers and two hybrid evaporative condensers to chill the cold water.
“To warrant high refrigeration capacity even in the event of a disruption, designers rated the two Chill-Pac chillers with an output of 730 kW each and installed them together with the main switchboard in a separate machine room on the ground floor of the energy centre. Direct condensation takes place using the two Jäggi hybrid chillers installed on the roof of the building, each with an output of 850 kW.”
It was noted that two Sabroe reciprocating compressor units can be operated independently if necessary so that if one compressor fails, 80 percent of the total needed refrigeration capacity can be provided by the other unit. Each compressor is equipped with a power control for energy-efficiency and the power stages are triggered and actuated by corresponding power solenoids.
And, noted Eurammon, “Each compressor has a frequency converter for speed control. In this way, the power stages are added constantly and the speed is increased when the system demands more power. When output is reduced, the power stages are switched back accordingly and the compressor speed is reduced. As the total refrigeration capacity of 900 kW is already generated when the two Chill-Pac chillers work at a capacity of 60 percent, the refrigeration experts managed to considerably reduce the noise levels. In addition, this power buffer permits dry operation of the hybrid chillers at nominal load up to an outside temperature of 21.5˚C (70.7˚F) so that no plumes of steam are emitted over the building as a result of evaporation.”
The 4,500 m² (49,000 square foot) Mercedes-Benz Sport Park in Kitzbühel, Austria, is a venue for school sporting events, training camps and professional contests.
The architectural plan called for a new ice rink to be erected on the Sport Park premises and entailed combining it with the already existing indoor tennis center. The refrigeration system was to supply the refrigeration capacity for ice hockey, a curling track, and a mobile outdoor ice surface.
In addition, the client wanted a refrigeration system to take care of the entire air conditioning for the sport complex (skating and curling, skittles, climbing, tennis, and restaurant). The curling track and the air conditioning had to be rated for operation all year round.
Said Eurammon officials, “Together with an energetically optimized, climate-neutral rating, the requirements included in particular a very low temperature spread across the whole curling track.”
The company Haas Anlagenbau planned and built an ammonia refrigeration system with direct evaporation for the ice hockey and curling facility. The system has two GEA Grasso reciprocating compressor units with a refrigeration capacity of 750 kW. Around 30,000 m (323,000 square feet) of evaporation piping was installed for the system. A secondary glycol circuit integrated in the central ammonia system is responsible for air conditioning. The mobile outdoor ice surface is also connected to the circuit.
Added Eurammon, “Haas Anlagenbau installed two different temperature levels to recover heat from the refrigeration process. The waste heat is used for air conditioning tasks and melting the snow pits. In addition, the refrigeration professionals equipped the refrigeration plant with a remote monitoring system for online support in addition to maintenance on site.”
The system engineers also worked with the Austrian authorities and Kitzbühel fire brigade to develop a corresponding safety concept for the ammonia refrigeration plant, which was located in the center of the city.
Publication date: 6/4/2012