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Rink 2 used an indirect2
ammonia (NH3
)/glycol system.
The direct R-22 system consisted of two eight-cylinder reciprocating compressors, a low-pressure receiver, two pumper drums, an evaporative condenser, and a waste heat recovery system. The total heat extraction capacity of this system was approximately 136 tons (1,632,000 BTUs/hour). After 27 years of operation, the aging direct R-22 system began experiencing issues such as corrosion in the vessels and rink oor piping; three maor leak events in the ice rink oor necessitated either signicant repairs or replacement of the system.
In 2009, the City of Brooklyn Park began working with Stevens Engineers to design an indirect ammonia (NH3
)/calcium chloride (CaCl2 ) system to replace both
rink refrigeration systems. Brooklyn Park selected the design for the following reasons:
The city already had experience using indirect systems in Rink 2;
The NH3
/CaCl2
system does not need to circulate refrigerant through the spectator seating area; and
The system reduces the rink’s environmental impacts. Brooklyn Park city ofcials elected to use NH3
as the
primary refrigerant in the new system because of its favorable environmental characteristics and high energy efciency. In comparison to R-22, which has a lobal arming Potential (P) of 1,8103 Depleting Potential (ODP) of 0.055,4 P and ODP.5
and an Ozone NH3
has zero Brooklyn Park selected CaCl2 as the
secondary refrigerant in the new system because of its observed higher efciency compared to glycol mixtures.
The modication of the ice arena’s refrigeration system was part of a larger energy efciency retrot proect that used stimulus money from the federal government’s Energy Efciency and Conservation Block to improve citywide energy efciency.
Schematic of the CAC’s current NH3
Source: Stevens Engineers 2
3 4
/CaCl2
refrigeration system. The NH3
/CaCl2
system is housed in the equipment room for Rink 2.
An indirect refrigeration system uses two refrigerants. A primary refrigerant stays confined in the ice equipment room and a secondary refrigerant is circulated in the rink floor.
Intergovernmental Panel on Climate Change (IPCC). 2007. orking roup I to the ourth Assessment Report of the IPCC (AR4). Available at: www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html
.S. EPA. 2014. Ps and ODPs of Some Ozone-Depleting Substances and Alternatives. Available at: www.epa.gov/ozone/snap/ subsgwps.html
5 Ibid.