Montreal is currently home to 40 municipal ice rinks that are in the process of being converted from the moribund R22 to ammonia under Canada’s contribution to delivering the Montreal Protocol targets. The metropolitan city is currently aiming to convert four ice rinks a year to ammonia, while standardising both their appearance and functioning. To deliver standardised ice rinks that are easy to install and maintain, the City of Montreal looked to heat exchanger manufacturer Alfa Laval for assistance. Alfa Laval’s ‘U-Turn’ helps Montreal turn its back on R22
The renovated ice rinks all utilise Alfa Laval’s ‘U-Turn’, a liquid separator designed especially for use with plate heat exchangers in ammonia applications. The U-Turn is placed on top of an Alfa Laval M10 semi-welded gasketed heat exchanger for the evaporator and an Alfa Laval AlfaNova 400 for the condenser.
The choice of the U-Turn has clear benefits for the operation and logistics of the ice rink as well as delivering a significantly reduced environmental impact. The U-Turn requires less floor space – as it can easily be mounted onto a compatible heat exchanger – and is quicker to install than the relatively cumbersome surge drum, which was used in the previous installation.
Ammonia is already an efficient and benign refrigerant, yet the U-Turn goes one better by allowing for a reduced charge, minimising the amount of refrigerant required and lowering operation costs as well as increasing safety. John Goswell, of Alfa Laval’s equipment division, expanded on the company’s efforts to minimise the charge size:
“Using our separator and heat exchanger design experience and features in our products allows us to have the smallest charge possible.”
As well as the importance of safety, which Goswell saw as cardinal, other factors also influenced Montreal’s choice of Alfa Laval:
Scope for natural refrigerants in North America’s ice rinks continues to grow
“There are benefits regarding efficiency and reducing ammonia charge […] Another important factor is the footprint of our system compared to an installation using shells and tubes, the U-Turn is much smaller and the system is much more responsive. A lot of existing facilities have height restrictions and our system –including the U-Turn separator – fits these requirements easily.”
The use of ammonia in Montreal’s ice rinks is part of a greater overall trend towards natural refrigerant solutions across the 2,600 indoor ice rinks in Canada and 1,900 in the United States.
The first use of CO2
transcritical technology for ice rinks in the United States was quickly followed by the second. Both sites were in Alaska, one in 2014 and the other in 2015, while CO2
transcritical continues to spread in Montreal. However, regulatory barriers are preventing the technology from spreading. Indeed, both Alaskan ice rinks were granted special exemptions, as the use of CO2
in ice rinks is yet to receive approval under the SNAP programme.
However, ammonia is a proven solution for ice rinks and continues to deliver perfect ice with increasing efficiency and safety. Both solutions ensure that as R22 continues be phased out, its successors will be around for quite some time, if the past is anything to go by. Goswell notes:
“The vast majority of ice rinks installed in the last 15 years have been ammonia; there have been a couple of CO2 transcritical. We are targeting older R22 systems that will need replacing.”