Ice Rinks: Which Refrigerant Is Best?

By Michael Garry, Dec 17, 2018, 23:01 17 minute reading

The National Hockey League and Chemours are promoting HFO blends R449A and R513A as green refrigerants, though ammonia and/or CO2 would be greener, say industry stakeholders.

Ice hockey was first played on frozen ponds, which are freezing later and melting earlier as a result of climate change.

Acknowledging the sport’s fundamental link to the environment and its preservation, the National Hockey League (NHL) – the 101-year-old organization now consisting of 31 professional ice hockey teams across Canada and the U.S. – launched the NHL Green initiative in 2010.

“Most of our players learned to skate on outdoor rinks,” said NHL Commissioner Gary Bettman, in announcing the program. “For that magnificent tradition to continue through future generations, we need winter weather – and as a league we are uniquely positioned to promote that message.”

For help in “greening” league games and operations, the NHL consulted with the National Resources Defense Council (NRDC). Each NHL team appointed one or more sustainability representatives to liaise with the league.

In 2014, the NHL released its first sustainability report, which provided data on its environmental impact. This was followed two years later by a program focusing specifically on ice rinks – the Greener Rinks Initiative; its mandate is to measure and evaluate the combined environmental impact of approximately 4,800 indoor ice rinks across North America, which have an average age of over 30 years.

The Greener Rinks Initiative is “committed to sharing sustainable business practices with community rink owners and operators,” according to the NHL.

In March of this year, the NHL released its second sustainability report, which reported that the majority of NHL arenas still use R22 or HFCs as refrigerants, with about 20% using ammonia.

R22’s days are numbered as production and import of the gas in North America are slated to end in January 2020. In May, the NHL promoted what could be a replacement refrigerant for R22, announcing a multi-year partnership with The Chemours Company to provide Opteon XP40 (R449A) and Opteon XP10 (R513A) to rinks across North America. (The announcement did not disclose any financial terms.)

The NHL and Chemours view this partnership as continuing the league's environmental stewardship, saying in the announcement that it “supports the NHL Greener Rinks Initiative."

But are R449A and R513A the most environmentally sustainable refrigerants to use in ice rink systems, particularly in new facilities?

A number of industry stakeholders point to natural refrigerants ammonia and CO2 as more sustainable and future-proof for ice rinks than the Opteon refrigerants being promoted by the NHL. This mirrors a similar discussion going on in other HVAC&R-related sectors like food retail and cold storage.

Ammonia and CO2 are the best true green solutions.”
– Art Sutherland, Accent Refrigeration Systems

Art Sutherland, president and CEO of Accent Refrigeration Systems, Victoria, B.C., a major designer and installer of ice rink refrigeration systems, strongly endorses the use of natural refrigerants in ice rink systems. “The whole world is going this way, moving away from [HCFCs] and HFCs, and now there’s concern about HFOs and their acidic nature,” he said. “Ammonia and CO2 are the best true green solutions.”

"It would be a shame if the NHL bypasses any opportunities to adopt truly low-GWP alternatives such as CO2 and ammonia,” said Christina Starr, Climate Policy Analyst for the Washington, D.C.-based Environmental Investigation Agency (EIA). “Particularly for new rinks and systems, these alternatives are available, proven, and offer opportunities for energy improvements over HFCs as well as direct climate benefits." 

Toronto-based CIMCO Refrigeration (a division of Toromont Industries) is a major designer and installer of ice rinks that claims to have installed more than half of the world’s rinks. The company offers a range of refrigerant options for ice rinks, including ammonia/CO2, ammonia/glycol, CO2 and “Freon,” which is Chemours’ trademark for a number of halocarbon refrigerants.  (Information on CIMCO's CO2 ice rink patents for the Canadian market can be found here.) 

For each project, CIMCO looks at initial cost, energy consumption and maintenance, and calculates total cost of ownership. “Generally low-charge ammonia/glycol or COare a better choice over a 20-30 year time frame,” said Benoit Rodier, CIMCO’s director of business development. “We present the business case and the customer takes a decision.”

Customers who choose Freon “are looking for the lowest initial investment and are not so concerned about efficiency over time,” he added.

In Canada, the government of Quebec is giving an incentive to ice rinks that replace R22 with either ammonia or CO2, and one-third of that incentive if HFO blends are used, noted Rodier. “The government recognizes the value natural refrigerants bring to the table.”

Given that previous generations of synthetic refrigerants – CFCs, HCFCs and HFCs – have prompted environmental regulations, “it makes no sense to use a fourth-generation synthetic molecule,” said Marc-André Lesmerises, a CO2 refrigeration pioneer who is president and founder of Carnot Refrigeration, Trois-Rivières, Quebec.

In Europe, “the cost [of HFOs] and potential environmental issues put an end to the discussion fairly quick,” said Jörgen Rogstam, managing director for EKA (Energi & Kylanalys), a Swedish firm focused on ice rink efficiency.

Operationally, natural refrigerants have performed well in studies of ice rink systems. A 2013 study by the Canadian government’s CanmetENERGY research group found that CO2 systems had the best COP (coefficient of performance) for refrigeration and heating (3.9), followed by NH3 (3.0) and HFCs (2.6); and the lowest annual energy consumption (111,748 TR / 393 MW per hour), followed by ammonia (149,281 TR / 525 MW) and HFCs (173,735 TR / 611 MW).

A report by CIMCO that included measures of horsepower expended per 100 tons of refrigerant, listed CO2 as the lowest (123.1/ 46.07 kW) followed by ammonia (123.5 or 434.3 kW), R513A (144.2 or 507.1kW) and R449A (168.8 or 593.6kW), among other refrigerants. CO2 was evaluated under a 65°F (18.3°C) condensing temperature.

On the issue of “glide,” natural refrigerants also have advantages. For example, COboils at a constant temperature, whereas R449A is a zeotrope, or a blend of refrigerants that boil at different temperatures. This temperature range, or glide, is a factor in evaluating refrigerants, with a potential impact on efficiency, said Tim Henderson, Hillphoenix’s industrial program manager.

In contrast with R449A, R513A is an “azeotropic refrigerant with zero glide,” according to Chemours.

Linde AG, a distributor of R449A, states in promotional literature that the refrigerant “has a moderate glide of approximately 4K that can be easily managed by a minor adjustment in the expansion device.” In addition, as a zeotrope, R449A “must be charged in the liquid phase to prevent fractionation.”

But Henderson pointed out that refrigerants with glide may require larger condensers and possibly larger evaporators with more surface area “to make up for the glide.” He has also heard of problems with “expansion valve sizing.”

Moreover, glide “has been proven to have a negative effect on the heat transfer performance of the refrigerant and may result in the chemical breaking down over a period of time,” said Dave Rule, president, International Institute of Ammonia Refrigeration (IIAR), Alexandria, Va.

Outreach to the community

The NHL declined to be interviewed for this article, deferring questions to Chemours, a Wilmington, Del.-based chemical producer formed in 2015 as a spinoff of DuPont.

Allison Skidd, Chemours’ North America marketing manager, fluorochemicals, described the NHL-Chemours partnership as providing “options for community rinks across North America that are faced with the need to address environmental regulations as well as economic sustainability concerns.”

Chemours and the NHL are working on outreach to community rink owners, operators and mechanical contractors “to offer resources for selection of safe, operationally cost-effective, environmental and financially sustainable alternatives, such as Opteon refrigerants which are non-ozone depleting and have low global warming potential,” Skidd said. The effort covers both retrofits of refrigerants in existing systems as well as equipment replacement in new and existing locations.

As to which refrigerant or system the 31 NHL teams will ultimately employ, “each team or arena owner will be the final decision maker after considering the many factors for their situation,” said Skidd. No NHL arena is known to have used Opteon refrigerants to date.

Meanwhile, NHL players have given an endorsement to ammonia. Last month the Edmonton (Alberta) Sun reported that Rogers Place, home to the NHL’s Edmonton Oilers, ranked second in ice rink quality in a poll of NHL players, coming in only behind the Montreal Canadiens. Both teams use ammonia-based ice rink systems.

Opteon refrigerants have been employed in “numerous systems across North America before and since the partnership began,” said Skidd. These include retrofits of R22, R507 and R134a, replacement of ammonia systems, and new rink installations. For example, the MARS Lakeview Arena in St. Cloud, Minn., has successfully operated “with lower operating cost and improved energy efficiency” since converting to R449A, she said. The facility uses R449A in a DX chiller (that replaced a flooded R22 chiller) with a glycol secondary fluid.

Meanwhile, many ice rink operators are using ammonia as a primary refrigerant coupled with a brine or glycol as a secondary refrigerant. CO2, both in direct and indirect (secondary) systems, is increasingly being employed by ice rink arenas in North America and Europe.

Asked to compare Opteon refrigerants with ammonia and CO2, Skidd said, “As A1 ASHRAE safety class refrigerants, Opteon XP10 and XP40 offer improved safety—with respect to toxicity and flammability—versus R717 [ammonia].  They also operate at lower pressures than R744 [CO2], which favorably impacts chiller efficiency, system reliability, and operating cost.”

The NHL and Chemours noted in their announcement of the partnership that many community rinks across North America continue to use soon-to-be-phased-out R22. R449A has become an alternative to R22 in some ice rink systems because “older R22 systems can be retrofitted to accept [R449A],” thereby avoiding the cost of a new system, wrote Alec Johnson on his blog.

Accent Refrigeration’s Sutherland acknowledged that that R449A and Honeywell’s R448A could be “drop-in” replacements for R22, while ammonia and CO2 could not.

Many rinks, noted Chemours and the NHL, also use high global warming potential (GWP) HFCs like R507 and R134a, which are being phased down globally via the Kigali Amendment to the Montreal Protocol. (The U.S. has yet to ratify the amendment.)

While Chemours promotes R449A as having a “low GWP,” Johnson called its GWP of 1,282 “a high GWP number”.  At a time when high-GWP refrigerants are being targeted by regulatory bodies throughout the world, “a high GWP number means tha [R449A] very well may be targeted for phase down or phase out,” he observed.

CIMCO’s Rodier views R449A, with its near-1,300 GWP, as a “transitional solution.”

R513A’s GWP (573) is about half that R449A, but it still considerably higher than the GWP of ammonia (zero) and CO2 (one), making it vulnerable to phase outs in regions like California that are looking at capping GWP in non-residential refrigeration systems at 150.

R449A and R513A both contain HFCs: R449A includes the HFCs R32 (24.3%), R125 (24.7%) and R134a (25.7%), while R513A includes R134a (44%).

Asked about how the phase-down of HFCs would impact Opteon refrigerants, Skidd replied, “In order to meet goals of the Kigali Amendment, the global HVACR (and other) industries will need to adopt a wide array of solutions, including pure HFOs, low-GWP HFO/HFC blends, and industrial gases [CO2, ammonia and hydrocarbons].”

“These solutions offer a range of lower-GWP options and involve trade-offs between performance, safety classifications, and total cost of ownership,” she added. “The Opteon portfolio of solutions will play an integral role in the industries we serve for the long term.”

Aside from the GWP question, R449A and R513A also contain R1234yf, which degrades readily in the atmosphere into trifluoroacetic acid (TFA), a very durable substance whose long-term environmental impact is still being investigated.

Natural refrigerant technology is “the only method that will ensure that future refrigerant phase-out regulations are avoided due to both current and unknown environmental issues,” said IIAR's Rule.

Sabres and Oilers tout ammonia

Ammonia systems have a big head start on other ice rink options. In Canada, about 90% of the rinks use ammonia, except in Quebec, where it's split roughly 50/50 between ammonia and R22, said Rodier.

Ammonia continues to be a refrigerant employed by NHL teams, including recent installations by the Detroit Red Wings, Buffalo Sabres, Edmonton Oilers, and the Las Vegas Golden Knights. (The Los Angeles Kings recently installed a CO2 ice rink system.)

The NHL has also employed an ammonia/glycol system to support its annual outdoor games played on temporary rinks in baseball and football stadiums across North America.

Last year, the NHL’s Buffalo Sabres replaced its 21-year-old R22 system with an ammonia-based system, which uses less electricity, said Ian Ott, senior manager of media relations for the team.

“It’s been performing very well,” he added. “Our ice quality is excellent. We haven’t had much in the way of maintenance costs.”

The Edmonton Oilers' Rogers Place opened two years ago with an ammonia/glycol system supporting two rinks with 400 TR (1406.74kW) of capacity.

The ice has been endorsed by such NHL stars as Sidney Crosby of the Pittsburgh Penguins and the Oilers’ Connor McDavid. The Oilers previously played at the Northlands Coliseum, where they used an ammonia/brine system.

“I’m a fan of ammonia refrigeration,” said Jason Rimmer, director of engineering and ice operation at Rogers Place. “Even for the simple fact that if there’s a leak, you know it. Freon is colorless and odorless, so if your detector is not working properly, you won’t notice a leak.”

Rimmer also prefers ammonia to Freon from an efficiency point of view. His energy costs are also reduced by virtue of the NH3 system’s heat recovery, which serves an indoor garage at Rogers Place and its hot water supply. “It’s capable of generating 6.25 million BTUs per hour (1831.69 kW),” he said.

The Rogers Place low-charge system uses only 550 lbs (226.7 kg) of ammonia. “I feel comfortable using it as there are many safeties in play,” Rimmer said. “Additionally, we ensure all of our department is trained in different situations by both classroom training as well as performing drills.”

Fernie accident

Sutherland of Accent Refrigeration, who has installed systems with HFO blends like R513A and R448A (from Honeywell), nonetheless always promotes ammonia as “the greenest and most efficient choice for ice rinks,” he said. “And for years that view was unopposed.”

But then a tragic accident happened in 2017 at the Fernie Memorial Arena in Fernie, B.C., where a catastrophic leak in a chiller with 1,000 lbs of ammonia took the lives of three technicians. The Fernie arena recently reopened after installation of a new ice rink chiller that uses Opteon refrigerant.

As horrible as it was, the accident has created what Sutherland and others in the ammonia refrigeration industry believe is an unfair perception of ammonia as an unsafe refrigerant. “It created a lot of fear among municipalities and rink operators,” he said, “and thrown a wrench into the whole industry.”

However, he pointed out, the fatalities at Fernie were the first related to ammonia in the ice rink industry’s 125-year history. (Other fatal accidents were the result of R22 leaks.)  “And the reason for it is that this system was really old and had been leaking for years,” he said. “The chiller should have been changed years before.”

With current technology, he added, the accident would not have occurred. As minor an addition as a $200 (€175.44) pressure relief valve on the secondary side of the system “would have saved these three people.”

Sutherland pointed out that there have been major advances in ammonia refrigeration that have rendered the technology vastly safer. One is lower ammonia charges, which have been cut to as low as 0.5 lb/TR. Modern ammonia ice rink chillers, he said, have less than 15% of the refrigerant charge used in shell-and-tube chillers of the past.

Sutherland remains confident that low-charge ammonia systems represents the direction in which the ice rink industry in British Columbia is headed, despite the Fernie incident.

Another safety advance is better airflow in buildings. “So if there is a leak you can get the ammonia out of the air quickly,” Sutherland said.

Next summer, Sutherland plans to install a “new style” ammonia system at a rink in Port Alberni, B.C., with innovative safety features. The system will contain only 60 lbs (27.26 kg) of ammonia and use calcium chloride brine as a secondary refrigerant; it will employ a low-charge “spray chiller” in which the liquid ammonia “vaporizes as soon as it hits the [evaporator] tubes,” he said.

In addition, in the event of a 25 ppm ammonia leak, a high-speed exhaust fan would be initiated; if a leak reaches 300 ppm, the Port Alberni system would close the solenoid valve on the outlet of the condenser and pump ammonia out of the machine room and into the condenser “in less than a minute,” he said. “It will safely contain the ammonia in the condenser.”

First NH3/CO2 system

Ammonia in combination with CO2 has proved to be an effective refrigerant solution for ice rinks.

Three years ago, Sutherland designed North America’s first ammonia/CO2 system for the Wells Fargo Sports Complex practice ice rink at University of Alaska’s arena in Anchorage, replacing a leaky direct system with 6,000 lbs (2721.6 kg) of R22. A separate machine house was built for the NH3/CO2 system.

“It’s a great system,” said Glenn Thomas, refrigeration technician for the University of Alaska. “It will last a long time and produce much better ice.”

Three years ago, Sutherland designed North America’s first ammonia/CO2 system for the Wells Fargo Sports Complex practice ice rink at University of Alaska’s arena in Anchorage, replacing a leaky direct system with 6,000 lbs of R22. A separate machine house was built for the NH3/CO2 system.

Ammonia/CO2 is a more expensive option than other systems but offers the best total cost of ownership, said Sutherland. “It’s a fairly long payback – over 10 years – but [the energy efficiency] gives you a payback over the lifetime of the system,” he said. Thomas noted that maintenance cost savings alone were considerable.

Sutherland believes an ammonia/CO2 system is more efficient than a CO2 system, though CO2produces high-grade heat for reclaim while NH3/CO2 generates low-grade heat.

But Rodier contends that in Canada, with its cooler northern climate, transcritical CO2 would be “a little more efficient than ammonia/CO2,” as well as less expensive. But for larger capacity rinks, NH3/CO2 would be needed, he added.

In any event, the NH3/CO2 system uses less energy than its predecessor at the University of Alaska, said Sutherland, though he acknowledged it was an old system. Energy is saved in several ways: the NH3/CO2 system employs an adiabatic condenser rather than an air-cooled condenser; and it reclaims more heat than the older model. 

In addition, the R22 compressors had to be run “full-tilt, all the time,” while the ammonia compressor runs “half the time, about 12 hours a day,” said Thomas.

Which means Ammonia and its natural refrigerant cousin CO2 are well-positioned to become the de facto future-proof alternatives for ice rinks.

To read the complete article in the Nov.-Dec. 2018 Accelerate America, click here. 

By Michael Garry

Dec 17, 2018, 23:01

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