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Different strokes

The Food Marketing Institute Energy and Store Development Conference considers the future of supermarket refrigeration, says Peter Powell

Refrigeration contractors are aware that the supermarket industry is working through a labyrinth of refrigerant system changes.

The sector is sensing the demise of high-GWP HFCs for use in HVAC systems, including some of the most commonly used refrigerants, R404A and R507. 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 HFOs, which are recognised as low-GWP alternatives to HFCs, and so-called natural refrigerants such as 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 two-day event did provide attendees with an update of what’s being worked on and what’s being used in some stores today.

Refrigerants

The conference took place shortly after the US Environmental Protection Agency (EPA) announced a proposal to, in effect, ban use of R404A, R507, 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. Mrs Hufford 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 is likely to carry global implications. “An HFC phasedown is increasingly likely,” said Mr Wilkins. “The issue is when and how – not if. Change in the supermarket industry is likely to accelerate.”

This change was highlighted through Mr Wilkins’ mention of CO2 systems that operate in a transcritical approach, or those that work in a cascade configuration using HFCs and HFOs.

Systems

Jeff Staub, application engineer manager, Americas, Danfoss, shared his knowledge on various low-GWP alternatives, noting that the proper refrigerant largely depends on specific “applications, regulatory requirements, region, and state of educational level in the service sector, among other reasons”.

Mr Staub noted that research in this regard is being done as part of the Air-Conditioning, Heating, and Refrigeration Institute (AHRI)’s Low-GWP Alternative Refrigerant Evaluation Programme (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. CO2 technologies are developing to overcome 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. Mr Anderson 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: centralised 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 watercooled 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, 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 much can be learned 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 US.

This article was originally published in The Air Conditioning, Heating and Refrigeration News www.achrnews.com

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