Due to the pandemic, many industry conferences and events went online this fall, which was a good thing, as this arrangement offered HVACR professionals the ability to learn about important issues from the comfort (and safety) of their homes or offices. At many of the events, alternative refrigerants — many of which are either mildly flammable (A2L) or flammable (A3) — were top of mind, and experts discussed how these solutions will impact comfort cooling and commercial refrigeration applications.

Refrigerant Choices

Last fall, Danfoss hosted the virtual Cooling United Live, a European-based virtual conference, which offered a variety of learning tracks including air conditioning, commercial refrigeration, food retail, and industrial refrigeration. For each track, attendees from around the world could choose to attend numerous panel discussions, live demonstrations, and small chatroom sessions from the convenience of their home or office.

In a roundtable held during the event, a panel of experts weighed in on which refrigerant was the right choice for commercial refrigeration applications. David Maguire, the moderator of the panel, asked, given the race for lower GWP, why doesn’t the industry just look for a good refrigerant with the lowest GWP and use that everywhere?

Panelist, Jorg Saar, global applications manager at Danfoss, answered, “Well, there is no one solution. I think we all can agree on that. There is not one single refrigerant that can cover it all. GWP is one criteria, but there are some others — it's cost of the whole system, it is the emission of the system due to its operation, it needs electrical energy to operate and that generates emissions as well. We don’t have one that does it all.”

Panelist Anders Juul, global marketing director of refrigeration at Danfoss, added, “There are also standards and safety, as well as charge limits and flammability. There is also the ease of service on different kind of systems. Of course, CO₂ in this area is different than, for example, one of the flammables, so it's something we need to take very much into account.”

Flammable refrigerants (e.g., ammonia, propane) do have an advantage over some refrigerants, noted Saar, because they can use a conventional system design.

“These offer very, very low GWP, and in addition, they are natural molecules, so they will probably never be banned. So we need to look at that as well.”

Juul countered that CO₂ is also a natural refrigerant, but unlike ammonia, it is not flammable, which can make it a good choice.

A2L refrigerants are another option, and panelist Thierry Raoul, global marketing director for refrigeration at Danfoss, noted that R-1234yf, R-454C, and R-455A can all be considered as part of the low-GWP solution.

“The charge limit of A2Ls is a little bit higher than A3 refrigerants such as propane, and we cannot forget that there are standards that need to be respected and considered,” he said. “Safety is also something very important, and while it’s fair to mention flammability, CO₂ has higher pressure, which must also be linked to safety in some extent.”

Pressure is an issue, agreed Saar, who said that many in the industry are not used to working with the higher pressures associated with CO₂.

“You also need new equipment, and you need to pay attention to asphyxiation, making sure that CO₂ will not collect somewhere,” he said. “With hydrocarbons, they offer a very normal pressure range, similar to what has existed so far. They are flammable, yes, but there are tools available so that professionals can handle these refrigerants in a safe way.”

While there are charge limits for both A2L and A3 refrigerants, one of the benefits of using CO₂ — particularly in the large distributed systems found in supermarkets — is that there is no charge limit, said Juul.

“Besides the pressure, CO₂ is an easy refrigerant to charge,” he said. “You don't need to collect it — you can vent it in the event that you want to do that. So that's the upside of using CO₂, and of course, we are also now seeing it in smaller systems.”

Maguire summed up the session, noting, “What I'm hearing overall, is that in the medium term and long term, there's really no one clear winner. Each approach has its own pros and cons, and there will be a mixture of approaches used.”

Saar agreed, noting that there will be no single solution used in commercial refrigeration. “We will see many different solutions on the refrigerant side, and clearly different system designs. It is not one fits all. If we ever did have that, we are far from it. That's over.”

Chillventa

Chillventa, the Nuremberg, Germany-based biennial event for the HVACR industry, canceled its in-person event and instead held a digital conference in October. The event included product presentations and technical programs that covered various aspects of refrigerants, including nonflammable low-GWP refrigerants for refrigeration and heat pump applications, illegal refrigerants, sensors for leak detection, and recycling.

Emerson offered several roundtable sessions that covered issues including future-proof refrigerants that can be used in residential and commercial comfort applications, as well as in refrigeration equipment. In the session entitled “Helping the Food Service Sector with Future-Proof Refrigeration Technology Using Low GWP A2L Refrigerants,” Hakan Ildiri, manager of refrigeration marketing at Emerson Commercial & Residential Solutions, discussed some of the issues that should be considered when designing refrigeration applications that utilize A2L refrigerants.

He noted that as far as cooling capacity is concerned, when compared to R-404A, nonflammable (A1) HFO blends below 2,500 GWP — including R-448A, R-449A, R-452A, R-450A, and R-513A — deliver similar values to R-404A. However, the cooling capacity can be higher or lower with some of the new mildly flammable (A2L) refrigerants below 150 GWP — including R-454A, R454C, R-455A, R-1234yf, and R-1234ze.

“As a result, it is necessary to be careful when choosing the refrigerant,” he said. “The system size and component selections must also be done according to the chosen refrigerant.”

Other important factors to consider when choosing an alternative to R-404A are mass flow rate, temperature glide, and discharge temperature, said Ildiri. It is also important for system designers to consider risk mitigation, which becomes a larger issue with mildly flammable refrigerants.

“Because of the flammability aspect of A2L refrigerants, there is a more detailed risk mitigation to execute,” he said. “For example, we can definitely say that when assessing flammability risk that A2L refrigerants are less critical than A3 refrigerants. But system designers must carry out the risk assessment for each individual system and define the appropriate safety concepts in accordance with the safety standards.”

Embraco brand, part of Nidec Global Appliance, also offered numerous roundtable sessions at Chillventa, including one entitled “Refrigerant Trends: R290 vs A2L in Plug-in Applications.” In this session, Marek Zgliczynski, R&D director - fellow researcher at Nidec Global Appliance (Embraco portfolio) and chairman of IEC/SC61C subcommittee, talked about the challenges of replacing R-404A and explained why R-290 (propane) is the best alternative refrigerant below 150 GWP.

“Flammable refrigerants that can replace R-404A are a major issue in plugin applications,” he said. “Options include various A2Ls (including R-455A, R-454C,R-457A) and propane, and we tested them all. Most of the A2Ls had better efficiency than R-404A, but in medium- or low-temperature applications, propane showed substantially higher efficiency than any HFC or HFC blend.”

In addition to being the most efficient refrigerant when compared to other alternatives, Zgliczynski said that propane offers other advantages, including low discharge temperature, no temperature glide, low refrigerant charge, low price, extremely low GWP, and lower operating pressures.

“Propane has already been on the market for quite a long time and its use in plugins is obvious,” he said. “At Embraco, we are ready for below 150 GWP, and we are offering propane for all of the various product sizes we have in commercial refrigeration.”