ST. LOUIS — Refrigeration contractors are aware the supermarket industry is working through a labyrinth of refrigerant system changes.
The sector is sensing the demise of high-global warming potential (GWP) hydrofluorocarbons (HFCs) for use in HVAC systems, including some of the most commonly used refrigerants, R-404A and -507. Even if the line between high- and low-GWP HFCs has yet to be drawn, the industry is considering low-GWP options more frequently.
Stakeholders are also taking a close look at synthetic hydrofluoroolefins (HFOs), which are recognized as low-GWP alternatives to HFCs, and so-called natural refrigerants like CO2 and propane.
With all that comes change in equipment that often results in systems comprised of mix-and-match pairings of various synthetic and natural refrigerants.
While there were no clear-cut answers or definitive solutions at the most recent Food Marketing Institute (FMI) Energy and Store Development Conference, the 2 ½-day event did provide attendees an update of what’s being worked on and what’s being used in some stores today.
The conference took place shortly after the U.S. Environmental Protection Agency (EPA) announced a proposal to, in effect, ban use of R-404A, R-507, and a number of other perceived high-GWP refrigerants from use in a wide range of commercial refrigeration equipment installed in 2016 or later. Drusilla Hufford, director, Stratospheric Protection Division, EPA, told the audience the proposal was part of the agency’s efforts to encourage the search for lower-GWP refrigerants that reduce overall risk to human health and environment.
One concern raised at the conference by a number of attendees was the timeline to bring new equipment to the industry that would work with the lower-GWP refrigerants. She said, “The EPA continues to seek comments on technical challenges, availability of alternatives, need for changes to manufacturing processes, safety upgrades, and its ability to meet proposed compliance dates.”
Robert Wilkins, speaking just prior to his retirement as vice president of public affairs for Danfoss, noted the EPA ban is just part of a trend that likely carries global implications. “An HFC phasedown is increasingly likely,” he said. “The issue is when and how — not if. Change in the supermarket industry is likely to accelerate.”
This change was highlighted through Wilkins’ mention of CO2 systems that operate in a transcritical approach, or those that work in a cascade configuration using HFCs and HFOs. And, he said. self-contained equipment operates with small hydrocarbon (HC) charges. Meanwhile, it’s no secret that “Legacy [existing] HFC systems are under increased pressure to reduce leaks and the switch to lower-GWP alternatives.”
Jeff Staub, application engineer manager, Americas, Danfoss, shared his knowledge on various low-GWP alternatives, noting the proper refrigerant largely depends on specific “applications, regulatory requirements, region, and state of educational level in the service sector, among other reasons.” He noted research in this regard is being done as part of the Air-Conditioning, Heating, and Refrigeration Institute (AHRI)’s Low-GWP Alternative Refrigerant Evaluation Program (Low-GWP AREP).
Regarding the no-GWP refrigerant sector, Staub said there are approximately 4,000 transcritical CO2 systems out there today. “It’s a mature technology. And, CO2 technologies are developing to overcome current challenges related to efficiency in high-ambient conditions, integrated HVACR applications, and smaller formats.”
When it comes to new stores, he urged the audience “to consider pilots with new technologies, natural refrigerant options, and alternative system architectures.”
Those systems formed the basis of a talk by Tim Anderson, principal engineer, Hussmann Corp. He looked at HFC, CO2, glycol, and propane refrigeration systems, considering their “strengths and weaknesses and how supermarket operators can determine which system is right for their companies and cultures.”
He looked at six system configurations: centralized parallel rack with R-404A as a baseline; distributed system; a system with CO2 on the low-temp side and glycol on the medium-temp side; cascade direct expansion with CO2 on LT and secondary CO2 on MT; transcritical CO2 on MT with cascade direct expansion CO2 in LT; and a water-cooled micro-distributed system.
After looking at pros and cons of each, he cited what he called two guiding principles. “There is no perfect solution, and the refrigerant choice cannot be separated from the system choice.”
In the Field
While the lower-GWP 407 Series of HFCs and propane were touched upon, the supermarket refrigerant referenced most often at the FMI event was CO2. The so-called natural formed the basis of a plenary session in which retailers told of their experiences with systems designed to work with the refrigerant.
Harrison Horning, director, equipment purchasing, maintenance, and energy — North, Delhaize Group SA, talked about the installation of a transcritical CO2 system at a supermarket in Turner, Maine, which served as a pilot project. Among the pilot’s findings, he said, were that project economics depend on many variables. Energy performance can be good, maintenance can be manageable, and we can learn a lot from Europe, Canada, and other parts of the world [where such transcritical CO2 systems are being installed at a more rapid pace than in the U.S.]
Benny Smith, vice president, facilities, Price Chopper Supermarkets, updated attendees on a cascade refrigeration system in Saratoga, New York, that combined CO2 with an HFC refrigerant.
One of the recurring themes in his presentation was the importance of involving service technicians in the entire process.
“Involve techs early on in the project,” he said. “Have them on the install and keep them well-trained and informed.”
Publication date: 12/29/2014