Montreal ice making innovation has garnered industry recognition at a fitting time of year. Claude Dumas, an engineer with the city of Montreal’s Direction des stratégies et transactions immobilières, received honours at ASHRAE’s winter conference earlier this week for spearheading the conversion of 47 municipal skating/hockey rinks from hydrofluorocarbon (HCFC) to ammonia refrigerant.
The ongoing switchover, expected to be complete by 2020, earned him the Milton W. Garland Commemorative Award, recognizing innovation and/or new technologies for refrigeration in a non-comfort cooling application. The system design employed in the Montreal rink retrofits meets that criteria by operating with less ammonia and at reduced pressure compared to conventional ammonia-based refrigeration plants.
In a paper written for the International Institute of Ammonia Refrigeration last year, Dumas and his co-authors noted the city’s twin goals to phase out dependence on HCFC-22, which has global warming potential (GWP) 1,760 times greater than carbon dioxide, and maximize safety in handling ammonia, which has zero GWP and ozone depleting potential, but is highly toxic and mildly flammable.
The design process focused on refrigeration components that either use or collect large concentrations of ammonia and then explored other options. The resulting design incorporates ammonia-to-glycol heat exchange in place of an evaporative condenser and a u-tube separator in place of the conventional surge drum.
“The innovation in this project is the use of the an equilibrium vessel designed to simplify the refrigeration system, minimize refrigerant charge, minimize controls and avoid the need for a refrigerant operating level control and a high-pressure receiver,” the paper states. “Our focus was always to reduce the risks through prudent design and implementation aimed at minimizing the ammonia refrigeration charge, surpassing industry standards and never compromising safety and performance.”
The 2016 paper draws findings from the 14 ice rink conversions that were complete at that time. Another 11 are now underway. Montreal was also a participant in a 2013 techno-commercial comparative study of refrigeration systems for ice rinks, conducted at Natural Resources Canada’s CanmetENERGY research facility in Varennes, Quebec.
