Farm Fresh’s advanced refrigeration system addresses the industry’s biggest refrigeration challenges: leaks and refrigerant quantity
Refrigeration exists in many types of retail outlets, but it is most closely associated with the almost endless variety of perishable products found in supermarkets. So it is not surprising that the responsibility for reducing refrigeration's environmental impact is falling squarely on the shoulders of the supermarket industry.
The industry is now beginning to awaken to that responsibility by driving a number of changes in refrigeration — changes that are making the technology not only more hospitable to the environment, but more efficient and cost-effective for supermarkets as well.
The latest supermarket company to step to the forefront of the refrigeration challenge is Supervalu, the retailing and wholesaling giant based in Minneapolis. Late last month, Supervalu announced that it is joining forces with the U.S. Environmental Protection Agency in the EPA's GreenChill Advanced Refrigeration Partnership, a voluntary program officially launched last November to promote a greener approach to refrigeration in supermarkets.
Supervalu has pledged that all 12 of its retail banners will participate in the GreenChill program's efforts to reduce refrigerant leaks, cut back on the quantity (charge) of refrigerants used, transition to refrigerants that don't deplete the ozone layer in the atmosphere, and develop more efficient refrigeration technologies.
Other retailers that have joined the GreenChill program so far include Food Lion, Hannaford Bros., Publix, Giant Eagle, Price Chopper, Harris Teeter and Whole Foods Market. The program also includes refrigeration equipment manufacturers Hill Phoenix, Kysor/Warren and Hussmann, as well as refrigerant manufacturers Honeywell, Arkema, Dow Chemical and INEOS Fluor.
The first Supervalu banner to publicly declare its involvement in GreenChill is Farm Fresh, Virginia Beach, Va., which operates 46 stores. The chain made its announcement on March 25 at the pre-grand-opening ceremony of a new 60,000-square-foot store in Franklin, Va., that features a number of innovative approaches to refrigeration.
“Farm Fresh is doing its utmost to build stores with as little impact on the environment as possible,” said Jonathan Perry, director of energy and maintenance for Farm Fresh, during the ceremony at the Franklin store.
The Franklin store, he said, uses 43% less refrigerant charge than stores operating three years ago (2,500 pounds, compared to 4,400 pounds for a conventionally refrigerated store of this size). It also employs about 9,000 linear feet of refrigerant piping, compared to about 25,000 linear feet in a conventional store, thus reducing the opportunity for leaks.
“If all supermarkets did this, there would be a significant impact on the ozone layer and on climate change,” said Keilly Witman, EPA spokeswoman, at the Franklin store. “We hope other supermarkets will look at what Farm Fresh has done here.”
BORROWING FROM RALEY'S
Two other retailer participants in GreenChill — Food Lion and Hannaford Bros., both divisions of Delhaize USA — have been developing and testing refrigeration systems that depart from the conventional DX (direct exchange) technology that is widespread in the supermarket industry. (See “Chilling Out,” SN, Feb. 11, Page 65.) Food Lion is exploring secondary-loop systems that employ alternative cooling substances like propylene glycol and carbon dioxide, while Hannaford has designed an unorthodox DX-type system that's well suited to a cold-weather climate.
Over the past three years, Farm Fresh, under Perry's direction, has also been developing an advanced DX-style refrigeration system that differs in many ways from a conventional design. “This takes DX to a higher level,” said Perry.
This system, deployed at the Franklin store as well as at eight other Farm Fresh supermarkets, is based on a design developed by Ed Est-berg, director of facilities, Raley's, West Sacramento, Calif., in 1993. Since then, Raley's has installed the system in 78 of its 135 stores.
Estberg's system is now built and marketed by Hill Phoenix, Conyers, Ga. “I did assist [Hill Phoenix] in making it a product they could sell,” he said in an email communication. He described the system as “just good, simple engineering use of standard practices.” He did not try to patent the system, because “there is not a level of originality that would justify a patent.”
Estberg believes that the advantages offered by his advanced DX design — lower energy usage, a smaller refrigeration charge and reduced maintenance costs — “would benefit the entire industry.” He has described the system publicly at the Food Marketing Institute's Energy and Technical Services conferences, including one presentation that was interrupted when word came in about the events of Sept. 11, 2001.
In addition to Farm Fresh, Estberg's design has been adopted by one store operated by Hy-Vee, West Des Moines, Iowa.
Reid Soady, a refrigeration executive at Food Lion who has observed Raley's advanced refrigeration system, said in an email communication that it “seems to be very sound.” Food Lion has looked into using similar compressors, but Soady said “they aren't a fit for our payback criteria for our current design.”
Food Lion “probably won't be looking to test the Raley's-type design anytime in the future, with the success we are having with carbon dioxide,” said Soady.
Perry was inspired to apply Estberg's design at Farm Fresh after seeing it work at Raley's. He persuaded Hill Phoenix to build a model based on Estberg's design. “Ed showed us 15 years of lessons learned and qualified us to build it,” said Scott Martin, director of sustainable technologies, Hill Phoenix.
The advanced system at the Franklin store uses R404A refrigerant, a non-ozone-depleting compound. Farm Fresh uses R404A in 11 other stores.
One of the key features of Estberg's advanced refrigeration design is that it uses what are called two-stage “open-drive” compressors, in which the compressor and its motor are physically separated from each other rather than being built together, as in a conventional system. The compressor in a refrigeration system compresses refrigerant gas, enabling it to be condensed into a liquid in the condenser, a process that generates heat.
Open-drive compressors have existed for more than 50 years but have been largely rejected by food retailers, who believe they are too vulnerable to shaft-seal leaks from excess vibration. However, today a laser alignment tool is available that aligns the compressor and its motor within a fine tolerance, significantly reducing vibration. “We shouldn't move away from open-drive compressors,” said Perry. “The danger [of leaks] has been minimized by technology.”
The advanced system uses six open-drive compressors — two for low-temperature cases (such as ice cream, frozen food), two for medium-temperature cases (fresh meat, dairy) and two for higher-temperature cases that operate at 36 to 40 degrees Fahrenheit (produce and floral).
Separating the compressor from its motor has a number of advantages. For one, the system does not have to remove heat generated by the motor that ends up in the condenser as in a conventional system. This improves the energy efficiency of the system by 20%, said Hill Phoenix. It also requires less maintenance.
The heat that is generated by the compressors is removed by a flat-plate heat exchanger. That reclaimed heat is conducted via heated water in a hydronic process to whichever part of the store needs it — a much more flexible setup than with traditional compressors. Heat reclamation is a way to reduce energy consumption in a store. In another store where this heat reclamation process is employed, the backup electric heaters have not been used.
The open-drive compressors are also designed so that oil drains out of them rather than building up. The oil circulates across the system in a cascading fashion. “With open-drive compressors, you reduce oil waste,” said Perry.
The air-conditioned “motor room” in the Franklin store where the compressors are housed features a closed design that prevents air from flowing into or out of the room. “This helps our leak detectors work better, and get technicians to the store faster” in the event of a leak, said Perry. The room uses a new Modular Refrigerant Leak Detection Sensor from Emerson Climate Technologies that has a sensitivity of 7 parts per million.
Another unusual aspect of the advanced refrigeration design in the Farm Fresh store is its use of “loop piping.” This means that a single line of refrigeration pipe, conveying liquid refrigerant from the condenser and motor room, is looped around the store above the sales floor, branching off into separate lines only when it reaches individual cases or walk-in rooms — “the farthest point that we can,” said Perry.
When liquid refrigerant is made to evaporate at the cases or walk-in rooms, it has a cooling effect, a process akin to perspiration evaporating from the skin. In the advanced system, the resulting gas is conveyed back to the motor room via three main suction lines that loop around the store.
By contrast, a conventional refrigeration system uses a “manifold” configuration, whereby two liquid and gas pipes connect each group of cases to the motor room. In a store with 45 groups of cases, up to 90 refrigeration lines would crowd into the motor room. The streamlined loop-piping scenario thereby saves a considerable amount of copper piping, cuts down the amount of refrigerant needed and reduces the potential for leaks.
The reduced use of piping also allows Farm Fresh to focus on insulating the pipes and securing them in individual “saddles,” which also helps reduce leaks. Perry said Farm Fresh is approaching a leak rate of less than 10% in the eight other Farm Fresh stores using the loop piping.
Other retailers have used the loop piping concept, though with more than one liquid line. The Franklin store, based on Estberg's model, “is the extreme case where it's just one liquid line,” said Perry.
In other ways, the Franklin store's refrigeration system uses fewer components than does a conventional store, employing only two condensers on the roof, one receiver, two oil floats and no oil separator.
Perry acknowledged that the advanced refrigeration system is more expensive “by a decent percentage” than a conventional system. However, he believes the payback is favorable, given the “energy savings, reliability and simplicity” of the system, as well as its expected longevity.
In addition, “by putting the best system in, we attract the best technicians,” he said. “A system is only as good as the technicians working on it.”
On the other hand, some technicians are intimidated by the novelty of the open-drive compressors. That's not an issue for Farm Fresh because of its proximity to U.S. Navy shipyards and retired Navy technicians experienced with open-drive compressors.
Perry said Farm Fresh plans to share information on the advanced refrigeration and its development with the EPA, as part of the GreenChill program. “We've improved on this every step of the way, and we'll continue to expand on what we've learned.”
Martin said the advanced system “is a great alternative with premium energy efficiency,” but noted that no refrigeration technology represents “a single answer for all situations.” Perry, however, intends to use it in future stores “until I see something better.”
In addition to the advanced refrigeration system, the Franklin Farm Fresh features an unusual HVAC (heating, ventilation and air conditioning) system that Perry designed called the “Climate Keeper.” Perry has installed this system in three other stores and plans to use it in new stores. Unlike a traditional approach to air handling, the Climate Keeper creates a neutral airflow, with little or no unwanted air entering or treated air leaving the store. (See “Shifting Currents,” SN, Sept. 24, 2007, Page 49.)
The Franklin store also employs an energy and refrigeration monitoring system supplied by Emerson that Farm Fresh refined. It monitors the motor room, display cases and many other areas of the store. The system is linked to Farm Fresh's central monitoring system at its headquarters.
Another environmental touch at the Franklin store is that it does not offer plastic bags. Only recyclable paper bags are provided, and shoppers are encouraged to purchase reusable bags for $1.99. Shoppers get a 5-cent refund for each reusable bag they bring, plus Farm Fresh donates 5 cents to the Chesapeake Bay Foundation.
Retailers that join the U.S. Environmental Protection Agency's GreenChill program commit to the following activities:
Using only non-ozone-depleting refrigerants in all commercial refrigeration applications in new construction and store remodels involving compressor rack additions or replacements.
Reducing emissions of ozone-depleting and greenhouse gas refrigerants every year. This includes establishing a refrigerant inventory and setting annual leak-reduction targets. It also involves collaborating across the industry to identify service and operational practices that reduce emissions.
Participating in an industry/government research initiative to assess the performance of advanced technologies that reduce refrigerant charge and minimize leaks.