The Canadian city has already converted most municipal skating and hockey rinks from R22 to environmentally friendly ammonia, with more conversions planned.
Claude Dumas, an engineer in the City of Montreal’s Direction des stratégies et transactions immobilières, won an award at this week’s ASHRAE – an industry association – winter conference for spearheading the conversion of 47 municipal skating and hockey rinks from HCFC 22 – GWP 1,700 – to ammonia.
Ammonia is a natural refrigerant with a GWP of zero. Montreal’s switchover is underway and will be complete in 2020. The design being implemented uses less ammonia and at reduced pressure compared to conventional ammonia-based refrigeration plants, improving system efficiency.
To achieve this, the designers focused on refrigeration components that use or collect large concentrations of ammonia, looking for other options. The end result uses an ammonia-to-glycol heat exchanger in place of an evaporative condenser and a u-tube separator in place of the conventional surge drum, allowing low charges to be achieved.
“Our focus was always to reduce the risks through prudent design and implementation aimed at minimising the ammonia refrigeration charge, surpassing industry standards and never compromising safety and performance,” Dumas et al. write in a paper for the International Institute of Ammonia Refrigeration.
Another 11 conversions to the same system design are currently underway in Montreal, with more to follow to deliver the full switchover by 2020.