The commercial refrigeration industry is being shaped at rapid pace by new refrigerants and refrigeration systems. At the second annual Contracting Business.com/Supermarket News "Refrigeration Roundtable" — held during 2011 Mechanical Systems Week in Indianapolis, IN — our contractor and super-market executive panelists shared their reactions to the fast-approaching departure of R22 refrigerant, their preferred alternatives, and which types of refrigeration systems have the most promise.
Jerry Stutler, vice president of construction and facility engineering for Sprouts Farmers Market, Phoenix, AZ, said Sprouts’ continues to convert more of its stores to R407F from R22 every year, adding that the price issues associated with R22 could be avoided if more stores would get busy and move to alternative refrigerants.
“If everybody starts to eliminate R22 today, hopefully we won’t run into the same situation we did with R12,” he suggested. “Everybody waited until the last minute on that one, and [the price] just skyrocketed. I think there’s going to be an abundance of R22 sitting around, stockpiles of it, and what we do with it after that, I don’t know. I don’t have the answer to that.”
Contractor Bill Almquist, president, Almcoe Refrigeration, Dallas, TX, (the Contracting Business.com 2009 Commercial Refrigeration Contractor of the Year) said many of his customers are converting to R422D and other gases. Almquist said system retrofitting is not as prevalent as it was four or five years ago.
Steve Hagen, procurement and engineering director for Fresh & Easy Neighborhood Market, El Segundo, CA, said the biggest challenge with refrigerant conversions is that often, compressor manufacturers aren’t on board soon enough, to rate compressors.
“Guys like Jerry and me, and probably some others around the country end up putting in refrigerants that technically void the warranty. Usually, you can get the refrigerant manufacturer to pick up that risk, but in the meantime you’re putting gas in the compressor racks that hasn’t been specifically designed for them. There aren’t really any issues there, other than you’re doing it kind of before the curve. I think a lot of the people who are really trying to get the global warming potential down quickly and control the refrigerant are trying the new refrigerants as early as possible.”
Bryan Beitler, vice president/chief engineer, Source Refrigeration & HVAC, Anaheim, CA, says Source Refrigeration and HVAC has explored a variety of conversion opportunities. Each one, he says, “has a life of its own.”
“There are many different refrigerants to convert in addition to R22 , such as Suva R408A from DuPont, a replacement for R502 in existing low- and medium-temperature commercial refrigeration systems. R402A, HP80, R409 and R401A are additional refrigerants that will eventually need to be converted.
“Each conversion is an engineering ‘event’ for which you have to figure out the right solution,” Beitler explained. “We would like to see store customers use refrigerants that have the lowest GWP. Having minimal changes to the system is the biggest driver, but there are many different flavors of new refrigerants that our customers have to choose from as replacements, to get beyond R22.”
Beitler said the greatest challenge isn’t to just “drop it in,” but to perform the engineering analysis up front — to specify the correct refrigerant type and proper modifications, which might affect efficiency, reliability, and leak rates, so that the customer receives the maximum benefits.
Hagen added that a refrigerant’s total equivalent warming impact (TEWI) shouldn’t be overlooked. TEWI is the total of direct and indirect emissions of greenhouse gases.
The ideal refrigerants are those which don’t sacrifice efficiency for GWP.
“Some of the advantages of R407A and R407F are that they’re proving to be more efficient in operation — not only are you reducing the GWP on the refrigerant, you’re also saving energy, which hasn’t always been the case with refrigerant options. These latest refrigerants have been a pretty good win-win option,” Hagen said.
Cascade, Transcritical Systems
New refrigerant systems gaining in attention include cascade systems — which perform refrigeration in two or more cycles in series — and transcritical systems, in which part of the system operates above the “critical” point (at which refrigerant condenses) and part operates below the critical point. Both are being used more often with carbon dioxide (CO2) as the refrigerant.
Jerry Stutler reported on a CO2 cascade system in the Sprouts store that earned an EPA GreenChill platinum certification for reduced refrigerant emissions. Installation assistance from manufacturers helped to make it a success.
“It seemed to be the one that made the most sense to us,” Stutler said. “We looked at the glycol systems and some of the issues people are having with glycol, such as downtime. I know you can go to steel pipe and maybe eliminate some of the downtime, if you had found some leaks on the glycol side when using plastic pipe. We partnered with Hill PHOENIX on this, and we felt they were well advanced in this system.
“Along with the Heatcraft microchannel air-cooled condensers, we were able to achieve the GreenChill platinum certification.” The CO2 system in use at the Sprouts store uses 235 pounds of HFC refrigerant, a 1,765 pound reduction in refrigerant compared to its previous system.
Looking forward, Stutler said he believed a small portion of coming transcritical systems will be high pressure, with the majority running at the same pressures at which a typical cascade CO2 system will operate.
The Efficiency of Alternative Systems
Are alternative systems — such as CO2, cascade, and secondary — proving to be more energy efficient than conventional systems?
“The CO2 cascade system is about 5% more efficient than our current DX system design,” Hagen said. “I’m going to guess that our ammonia system (see Ammonia Comeback, below) will be in the same range in terms of savings.
“The compact chiller CO2 glycol system is probably going to be the same as others’, a few percentage points higher in energy cost.”
Stutler offered that his cascade system is showing higher energy consumption, but it’s still in a test phase.
“We’re still trying to come up with a perfect comparison with some of our other systems, so I’m not giving a percentage,” Stutler said. “What I will say is that, even if you’re 5% higher, with the reduction of the HFC refrigerant that you pulled out of the store, the carbon footprint reduction far outweighs the energy increase.”
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George Ronn, senior manager, refrigeration compliance and system controls, SUPERVALU, Minneapolis, MN, and Steve Hagen, reported to the panel their use with ammonia as a primary refrigerant for a system, with CO2 as the secondary refrigerant. We asked their opinions on issues that exist with ammonia.
“One of the big issues is to make sure the local authorities understand the ammonia system, because the charges are relatively small overall,” Ronn said. “Of course, you always have the possibility of air inversion, or fog, that’s going to hold the odor if you have a leak, but the amount of ammonia involved isn’t enough to be considered toxic unless it’s in a confined space.
Ronn said ammonia users would let their neighboring stores or residents know that they will smell ammonia in the event of a leak, “but it’s not like a railroad incident, where there’s a tank car leak, and you clear out an entire city block. You’re not talking toxicity or even odor to that level. But, in most instances, even if there were a leak, ammonia is lighter than air, and is going to rise.”
Steve Hagen said the ammonia system installed by Fresh and Easy has less capacity because glass doors were added to the design, and the 48 pound system is on the roof of the store.
“If there’s a system issue that causes it to shut down or go over pressure, it dumps the ammonia into a water tank, so you don’t get a release,” Hagen explained. “It’s only released if a line breaks, and then, you’re looking at four different systems that each have 12 pounds, and the gas is going to rise. And when you think of all the air between you and anybody else, it’s going to disperse.
“The ammonia you use for cleaning is a 1% solution. The ammonia used in refrigeration is a 99% solution, so you can imagine how much stronger the smell is. You never have to worry where the leak is; you can find it quickly.”
Richard Adkins, director of marketing, Advantage Refrigeration, Berlin, WI, believes ammonia is coming back. It has a history of success in refrigeration, and would only be used in small quantities.
“Being an ammonia contractor, we deal with systems that have over 10,000 pounds of anhydrous ammonia. Anything over 10,000 is highly regulated by OSHA and EPA, which requires process safety management (PSM) and other programs.
“It’s a refrigerant that’s been used for years, and it was one of the very first refrigerants. In coming back to it now, I think it’s going to be a great refrigeration for supermarket applications.”
The 2011 Refrigeration Roundtable was a great success, as many ideas were shared among supermarket managers and refrigeration contractors. Each Roundtable we’ve hosted has been a fine example of the cooperation that exists between the best of the best. “This was over the top,” said Bill Almquist.
Our 2012 Refrigeration Roundtable is showing all the signs of being an equally valuable educational experience. We’ll report every word from this closed meeting in four installments, from Dec. 2012 to August 2013. Until show time, be sure to visit our show website: MechanicalSystemsWeek.com and register for Mechanical Systems WEEK.