SYSTEM DESCRIPTION The new indirect NH3

/CaCl2 charge size of 387 pounds of NH3

system has a refrigeration , which replaces the

6,000 pounds of R-22 and 1,200 pounds of NH3 used in

system. The renovated equipment room now houses three compressors on concrete pads, an above-ground NH3

the previous systems. Brooklyn Park expanded the ice equipment room for Rink 2 to accommodate the NH3

/CaCl2 containment tank, a chiller, a leak

detection system, heat exchangers, and a combination of welded steel and high-density polyethylene piping. Each rink oor has approximately 10 miles of 1-inch piping.

Other Sustainability Measures

In conunction with replacing the rinks’ refrigeration systems, three other cutting-edge modications to the facility were made:

1) Replaced the energy- and water-intensive cooling towers used to cool the refrigeration system with a well connection to the city’s raw water system.

2) Used the city’s raw water as a geothermal coolant to reduce the refrigeration system’s energy use. The connection from the well provides water at 49, which allows the compressors to operate at temperatures lower than the minimum temperatures listed in the manufacturer’s specications. The lower operating temperature requires half the electricity and produces double the capacity of a typical system.

3) Balanced the heating and cooling loads through an advanced control system, which makes use of warm and cold outdoor air when temperatures are advantageous to the system. The design allows heating systems to utilize waste heat in the facility from dehumidication, rink heat, snow melting, resurfacing, and suboor heating.

The CAC’s current NH3 indirect NH3

/CaCl2 700 pounds of NH3 /CaCl2 refrigeration system. The new

system has a refrigeration charge size of . Source: Stevens Engineers

SYSTEM PERFORMANCE AND COSTS

The Brooklyn Park CAC ice rink is now considered one of the most energy efcient ice rinks in the United States, and possibly the world. The new system requires half the energy of the previous systems to perform at the same capacity. The unique heat design and incorporation of the heat pump system allows the recovery and reuse of 95 percent of the waste heat that is generated from the refrigeration system. When compared to an indirect R-507 system, the two-sheet ammonia-based system is at least 15 to 20 percent more energy efcient. The Brooklyn Park CAC ice rink is also achieving additional energy efciency gains due to the integration of the geothermal exchange system. The system uses advanced controls to lower the condensing temperature from a typical 96 for NH3

to approximately 5257, resulting in increased

operational efciency. Overall, the city’s energy efciency retrot proect is reducingits annual electric and natural gas consumption by 317,000 kWh and 11.1 million ft3

,