|Planning / Implementation / Main components:||Francks Kylindustri AB, screw compressors by Bitzer Kühlmaschinenbau GmbH|
|System start-up:||October 2007|
Tingvalla Ice Stadium in Karlstad, Sweden, is Europe's largest open air stadium with an ice rink measuring 65 x 180 metres. It is used for bandy, a version of ice hockey that is popular in Scandinavia and Russia. The stadium's refrigerating system has been completely renewed to safeguard the refrigeration concept for the years to come.
The task facing the contractor consisted in safeguarding operation at outside temperatures of 12°C, keeping the ice temperature at a constant -4°C. Further demands made of the refrigerating machine included high energy efficiency and low operating costs, together with minimum maintenance.
The contractor built a cascade system using 1.3 tonnes of ammonia as refrigerant and 16 tonnes of carbon dioxide as secondary refrigerant with partial evaporation. The refrigerant cools the carbon dioxide at an evaporation temperature of -12°C. The carbon dioxide is stored in four accumulators which are connected with the ammonia system by heat exchangers. This condenses the secondary refrigerant which comes back partially evaporated from the four separately switched cooling circuits measuring 65 x 45 m, installed underneath the ice surface. Cold production on the ammonia side is generated by three one-stage screw compressor combined sets with a total refrigerating capacity of around 2,300 kW and a pumping volume of 4,100 m³ per hour. Altogether, ten open screw compressors by Bitzer are used: two of the combined sets have three compressors each, the third set has four. Each compressor is directly coupled to a drive motor with a rated output of 110 kW. The motors are in the highest energy efficiency class. Each set is equipped with a multi-stage oil separator with a separating volume of 700 dm³. To cool the oil, each set is connected to a joint ethylene glycol circuit by means of a plate heat exchanger. The ethylene glycol is pumped to a central recooler on the roof of the machine house where it cools down against air.
|Type of facility||Cascade system|
|Refrigerant volume||1.3 t|
|Main components||3 one-stage screw compressor combined sets, 10 open screw compressors by Bitzer, 4 accumulators, 3 multi-stage oil separators, 3 plate heat exchangers, 1 central recooler, 1 ammonia evaporator, 3 wet cooling towers|
|Special features / Comments:||
The combined sets drain the ammonia evaporator through a central intake pipe; the evaporator works in flooded mode for the highest possible thermodynamic efficiency. Three wet cooling towers connected in parallel positioned outside next to the machine house are responsible for condensing the ammonia.
Bitzer Kühlmaschinenbau GmbH
Phone : +49 (0)7031 932 155
Fax: +49 (0)7031 932 147