C[O.sub.2] was previously used solely as the secondary refrigerant in ice rinks, but C[O.sub.2] today is also applied as the primary refrigerant
. Systems using C[O.sub.2] as the primary refrigerant
in this article are referred to as second-generation ice rink C[O.sub.2] systems.
This simulative work compares two different primary refrigerant
cycles of a secondary loop system: The first system is equipped with R-134a which is widely used throughout the automotive industry.
* Cascade Systems: 1100 lb (499 kg) of primary refrigerant
, and 430 lb (195 kg) of C[O.sub.2]
The system operates with natural ammonia as the primary refrigerant
, cooling a glycol secondary fluid.
The technology uses a 35% aqueous propylene glycol fluid, a non-greenhouse emissions-producing secondary fluid, as a primary refrigerant
. This low-pressure "chilled water" loop eliminates the circulation of high-pressure refrigerant throughout the sales floor area.
Because the units are designed to accommodate only the secondary refrigerants, they won't have to be replaced if future regulations require replacement of HCFCs or HFCs as primary refrigerants
. Not only that, but the Electrolux system needs only 20% as much primary refrigerant
as a conventional system.
Ice rinks that use C[O.sub.2] as the secondary refrigerant in combination with any primary refrigerant
are referred to here as "first generation." The first ice rink to be built with pump-circulated C[O.sub.2] as a secondary refrigerant and ammonia as the primary refrigerant
was the Dornbirn ice rink in Austria in 1999.
This improved concept has demonstrated its ability to reduce by at least 82% the quantity of primary refrigerant
They are served by a secondary refrigeration system with a glycol solution as the secondary and ammonia as the primary refrigerant
. A 965kW Sabroe chiller combined with two screw compressors produces glycol at 10[degrees]C with a return temperature -5[degrees]C.
Reducing the primary refrigerant
charge is usually achieved at the cost of reduced efficiency because of the extra temperature differences required to transfer heat through the secondary refrigerant.
The refrigeration experts International Controlled Atmosphere Storage and SRS Frigadon designed a brine system using propene as the primary refrigerant
. The system was completed in 2008 with an output of 1,150 kW (327 ton).
Secondary loop technology uses about 60% less primary refrigerant
to chill a heat transfer fluid that is distributed to store display cases.