Stop & Shop Green Refrigerant Technology Reducing Waste, Costs
Stop & Shop new store in West Hartford, Conn., -- it’s first to earn GreenChill Gold status – is already seeing benefits from the environmentally-friendly equipment it installed during the store’s construction.
The grocer worked with refrigeration partner Hill Phoenix to install refrigeration systems designed to provide significant energy savings and a reduced carbon footprint. Stop & Shop selected Hill Phoenix’s Second NatureR technology for both its low and medium temperature display cases and walk-in coolers. Second Nature systems are designed to keep refrigerated and frozen foods at optimum temperatures while using the latest technology to minimize environmental impact.
“Even though it has only been a few months, by using the Second Nature system with glycol, we’ve already seen a reduction in the HFC refrigerant charge,” said Cary Nix, manager of engineering for the New York/New England division of Stop & Shop. “We’re using 1,100 pounds of refrigerant, compared to about 2,600 pounds you would typically need for a store this size, which is a 58 percent savings.”
Second Nature Medium Temperature are designed to cut refrigerant charge by more than 50 percent over a standard DX system. The system achieves this by replacing a significant amount of halogenated fluorocarbon (HFC) refrigerants, which is a contributor to global warming, with food grade propylene glycol At this location another step was taken to lower potential greenhouse gas emissions by replacing R404A with R407A, an HFC refrigerant with almost half of the global warming potential of R404A.
Another advantage of the Second Nature Medium Temperature technology is the system’s variable speed drives, according to Hill Phoenix. The Second Nature system at the West Hartford store uses two 7.- horsepower pumps with variable speed drives. Incorporating the drives on the glycol pumping station allows the system to provide precise capacity control throughout the operation.
According to the vendor, using the variable speed drives with end-of-loop pressure controls on the glycol circulating system allows the system to optimize the flow rates at each display case and cooler. By producing only the refrigerant capacity each refrigerated unit needs, excess cooling is eliminated and a store can achieve an average energy savings of 40 percent over traditional pumping systems.
In addition to its sustainability benefits, the use of the chilled glycol system and its ability to control product temperatures is especially effective for medium-temperature applications such as meat, seafood, and produce cases. With the Second Nature system, temperature control is more stable, thus eliminating large temperature swings.
For the store’s low temperature display cases and walk-in freezers, Stop & Shop selected a Hill Phoenix Second Nature direct expansion cascade system. While most low temperature systems use HFC refrigerant as the primary means to refrigerate freezers, the Second Nature low temperature direct expansion cascade system (SNLTX2) uses CO2 condensed by the medium temperature compressor system. This is the same compressor system that is used to chill the propylene glycol for the medium temp cases & walk-in coolers. CO2 is considered a natural refrigerant and component of the environment, has excellent thermodynamic and transport properties and has good material compatibility, according to Hill Phoenix.
Additionally, it provides a significant decrease in refrigerant charge and an advantage to stores in both sustainability and cost. With only 650 pounds of R744 (CO2), the cascade system is able to significantly reduce costs: CO2 is an inexpensive refrigerant, costing only a fraction per pound compared to the price per pound for HFCs. By using this technology, Stop & Shop expects to realize significant savings.
The proprietary Hill Phoenix SmartValve Superheat Management system reduces refrigerant requirements and eliminates the need for excess amounts of refrigerant storage within the system that typically accommodates wide swings in ambient conditions.Hill Phoenix said that the SmartValve technology reduces the pull down time after defrost from 32 minutes to just 11 minutes, resulting in an approximately 9 percent reduction in kilowatt usage.
The Second Nature compressor system can be monitored via the Copeland Intelligent Store Discus Compressors, which have all the on-board diagnostic controls built into them, allowing Stop & Shop to monitor everything right on the spot.
Through the use of these systems, the total annual carbon footprint of the store will be reduced by over 976 thousand pounds of CO2, which is equivalent to removing 811 passenger cars from the road or recycling more than 1,500 tons of waste over 10 years. And, with a 58 percent reduction in initial refrigerant charge and leak rate reduction for the life of the system, the carbon emissions savings will be more than 4,883 tons of CO2 over a 10-year period.
For recognition of its sustainability accomplishments, Stop & Shop West Hartford has been awarded GreenChill Gold-Level Certification from the GreenChill Advanced Refrigeration Partnership, a voluntary Environmental Protection Agency partnership with food retailers to reduce refrigerant emissions and decrease their impact on the ozone layer and climate change.
The certification program recognizes individual stores for using environmentally friendlier commercial refrigeration systems. The Stop & Shop West Hartford store has achieved Gold Level Certification for using only non-ozone depleting refrigerants, achieving an average HFC refrigerant charge of 1.218 pounds of refrigerant per 1,000 BTU per hour total evaporator cooling load, and a storewide annual refrigerant emissions rate of not more than 12 percent.
Quincy, Mass.-based Stop & Shop operates more than 390 stores throughout Massachusetts, Connecticut, Rhode Island, New Hampshire, New York, and New Jersey.