At a meeting of the Consumer Goods Forum in 2010, where some major food retail chains were discussing developments in natural refrigerant refrigeration technology for new stores, there was “the elephant in the room,” recalled Harrison Horning, director of maintenance for Hannaford Supermarkets.

“It was, what are we going to do about the thousands of existing stores in the U.S.?” he said. “And it’s still the elephant in the room. Maybe by 2020, 10 years later, we’ll have an answer.”

One possible answer that Horning is starting to explore is whether self-contained display cases using propane (R290) as the refrigerant could be systematically employed in existing stores to replace cases at the end of their life. That would be a way of incorporating a natural refrigerant in the many thousands of existing stores in need of updating.

New store construction has been sparse for Hannaford in the last five years, but existing stores are in continuous need of upkeep. “A lot of the time we need to replace a few cases here, a lineup there,” said Horning. “So we’re looking to get a natural or low-impact solution that will address replacement of existing cases – not necessarily everything at once.”

To prepare for that approach, Horning is testing R290 in complete frozen-food lineups in some new stores, in combination with a glycol/water secondary loop system serving medium-temperature cases.

Hannaford was one of the pioneers of transcritical CO2in U.S. supermarkets, installing the first such system at a store in Turner, Maine, in 2013. Since then the Scarborough, Maine-based chain – now a part of the Ahold-Delhaize – has installed transcritical refrigeration in another new store, as well an existing store.

But Hannaford, like many other U.S. food retailers including Target, ALDI US and Whole Foods Market, has been widely deploying self-contained R290 cases in hundreds of stores as spot add-on or replacement merchandisers in stores mainly served by central rack systems.

Now, a growing number of U.S. retailers, including Hannaford and Lidl (both with European parents) regard R290 self-contained cases as a partial or even full-store solution in lieu of a central rack-based system. The equipment is being supplied by such manufacturers as AHT Cooling Systems USA, Hussmann and True Manufacturing, among others.

“We’re looking to get a natural or low-impact solution that will address replacement of existing cases – not necessarily everything at once.” 

Harrison Horning, Hannaford Supermarkets

The idea of testing R290 as a primary store refrigerant was proposed to Hannaford by Clive Samuels, president of Coolsys Energy Design, an engineering consulting company based in Princeton, N.J. “They said, ‘You need to try this’ and pulled up the HEB [R290 store],” said Horning. “I didn’t see this one coming.”

In July 2013, HEB (H.E. Butt Grocery, San Antonio, Texas) became the first U.S. grocer to install propane-based self-contained cases from Hussmann throughout an entire store.

Hannaford’s 20,000-sq-ft store in Mechanic Falls, Maine, which opened last year in July, offered the chain its first opportunity to test the installation of a complete lineup of low-temperature R290 cases (from Hussmann), whose excess heat is removed by a loop of glycol that’s chilled to 45°F by a R407A rack/chiller (a rack combined with a heat exchanger).

The glycol loop is what allows R290 cases to be used on a full-store basis, said Richard Gilles, senior product leader for Hussmann’s Distributed Systems Group. “With the [glycol] loop, you get more capacity and it allows us to use larger cases. It’s also scalable so you can have as many cases as you want.”

Since then, Hussmann has introduced the microDS line of R290 cases; waste heat from these cases is withdrawn by a closed glycol loop with temperatures running between 50°F and 115°F, and cooled by a roof-mounted dry fluid cooler.

Operationally, Horning considers the low-temperature R290 cases to be “pretty efficient,” adding, “We have no reason to doubt that.” But Hannaford’s focus with natural refrigerants is more on their substantial reduction of greenhouse-gas emissions than on “a 5%-10% swing in energy,” he noted.

Regarding upkeep, he has had to address overheating in some R290 units, though it “was an easy fix.”  He is not aware of any propane leaks in R290 cases. Maintenance at the Mechanic Falls store is “normal” and “simpler than a rack,” though he noted the system is only six months old. Hussmann allows technicians to monitor and diagnose issues in the R290 cases via their cell phone.

As its next step, Hannaford plans to deploy Hussmann’s  microDS system in 2019 at a new 39,000-sq-ft store in Ballston, N.Y. “This is a chance to make it better and [continue to] see how it could apply in existing stores” as well as new stores, Horning said.

Unlike the Mechanic Falls store, the Ballston store will use a fluid cooler to chill the glycol for the R290 cases; it will be an adiabatic model, which “gives us a comfort level” on hot days, Horning said. The glycol loop will also be used for heat reclaim.

“It’s exciting to see a big company like Hussmann have catalog [R290] equipment now,” said Horning, adding that this enables merchandisers to continue operating with familiar equipment. “There’s definite interest in R290 self-contained [among U.S. manufacturers]. They are taking it seriously.”

Horning expects to test the R290 low-temperature cases as freezer replacements in an existing store near Ballston as well as others this year or in 2020. “We’ll start putting in new cases and connecting them to a cooling loop,” he said. He envisions replacing medium-temperature cases with models served by a glycol loop connected to a rack converted to a chiller. “That’s a lot less expensive than replacing everything. We do it piecemeal as a maintenance activity like today.”

Glycol for medium temperatures

On the medium-temperature side of the two new R290 stores, Hannaford is employing an R448A rack/chiller to cool glycol to 20°F, and delivering it to the medium-temperature cases and walk-in coolers as a secondary cooling agent (in contrast to the low-temperature cases, where glycol condenses R290). Horning believes Hannaford has overcome the energy penalty traditionally associated with pumping secondary glycol through a store as a cooling agent.

“We’re using copper piping that is sized a little bigger than normal so the pressure drop is less and the pump energy is less,” he explained. In addition, Hannaford saves “a ton” of energy through the adroit adjustment of compressor head pressure during the cold New England winter.

Though it will use R448A in the rack/chiller in the Ballston store (and in a condensing unit serving two walk-in freezers), and R407A in the Mechanic Fall store, Hannaford is planning to build three new stores in 2019 and 2020 that will employ CO2in the rack/chiller to chill secondary glycol, along with R290 low-temperature cases, creating an all-natural store. Horning had originally expected to install transcritical CO2systems in those stores, but his merchandisers preferred cases not designed for CO2.

Hannaford also expects to supplement its glycol-loop low-temperature R290 cases with air-cooled medium-temperature R290 units like the beverage and island cases it is already using in some stores.  A small low-temperature lineup of cases could also be air-cooled, “but you have to be sure to manage the heat gain in the hot season,” Horning said.

He leaves open the door to using more air-cooled or water-cooled R290 medium-temperature cases instead of secondary glycol as another possible natural refrigerant “end game.”

Meanwhile, the combination of R290 frozen-food cases and secondary glycol medium-temperature cases represents “a significant improvement over what we have, and moves us toward the end game,” said Horning.

The cost of the natural refrigerant systems Hannaford is evaluating is comparable to that of its previous standard (an HFC system optimized for the chain’s climate zone), and the pilot stores “will help us validate this assumption,” said Horning

Meanwhile, Hannaford has not yet settled on a final standard, though transcritical CO2has been its new-store standard to date.

Horning acknowledges a particular fondness for the “plug-and-play” capability of R290 cases. “By the time I get to the end of my career, I’d love to know that when you are replacing cases in the middle of the night it can be as easy as wheeling them in and plugging them in,” he said.

While there is much anticipation for the charge limit of hydrocarbons in commercial cases being raised to 500 g from 150 g, Hannaford’s strategy is not dependent on the limit being raised, said Horning. He is satisfied with current equipment and is pleased that U.S. manufacturers are not “waiting for higher charge limits” to offer R290 cases.

Horning agreed a higher charge limit would cut the number of required condensing units. But, he added, the 150-g charge limit has forced manufacturers to make self-contained condensing units “small, quiet and reliable – is that a bad thing?”

Meanwhile, the International Electrotechnical Commission (IEC), the body that sets widely followed reference standards for charge limits, is expected to start its final vote on whether to increase the charge limit to 500 g for A3 refrigerants in mid-March, and conclude in mid-May, said Marek Zgliczynski, Embraco’s director of research and development, who chairs the IEC SC61C subcommittee.

To read the complete Accelerate America cover story, “R290: The Future of Retail Refrigeration?” from which this article was excerpted, c;ick here.

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