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 maor leak events in the ice rink oor necessitated either signicant 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 ofcials elected to use NH3


as the


primary refrigerant in the new system because of its favorable environmental characteristics and high energy efciency. 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 efciency compared to glycol mixtures.


The modication of the ice arena’s refrigeration system was part of a larger energy efciency retrot proect that used stimulus money from the federal government’s Energy Efciency and Conservation Block to improve citywide energy efciency.


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.


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