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The refrigerant R-744 (CO2) has gained one of its strongest footholds yet in the commercial refrigeration sector with the announcement that the Environmental Protection Agency (EPA) has “found it acceptable for replacing HCFC-22 in supermarkets.”

“The green light came under the EPA’s Significant New Alternatives Policy (SNAP) program, which evaluates alternatives to substances being phased out to protect the stratospheric ozone layer,” said David Hinde, manager of research and development for Hill Phoenix, the manufacturer of supermarket equipment who provided the submission to the SNAP program.

The move means that R-744 can be used in new installations that might have previously opted to use R-22. The approval does not relate to the retrofit of existing R-22 systems.

While Hill Phoenix was the first to receive SNAP approval for CO2 use in supermarkets as a replacement for HCFCs, any manufacturer in the sector can apply the technology, according to both the EPA and Hill Phoenix. To launch the submission process, Hinde said Hill Phoenix conducted lab and field-testing for more than a year before submitting its SNAP application. He said the company would continue to test CO2 in projects this fall. It will begin offering CO2 as a refrigerant option in both its Second Nature® low temperature secondary loop and medium temperature products in late 2009, he said. Hill Phoenix has offered R-744 in low temperature secondary loop systems since 2006.

Although not directly related to the EPA SNAP announcement, Hinde said CO2 could also be used to replace HFC-507A or HFC-404A. “CO2 is an excellent refrigerant with superior thermodynamic and transport properties,” he said. “It will not only significantly reduce the potential for global warming, but the refrigeration systems that incorporate CO2 will also see a reduction in energy consumption.”

By replacing the HFCs with CO2 as the medium temperature secondary heat transfer fluid, a supermarket’s display cases and walk-in freezers will be able to utilize the natural refrigerant to chill perishable products. Hinde said that by using CO2, refrigeration systems would be able to reduce HFC refrigerant leaks as well as reduce the HFC charge anywhere from 60 to 90 percent.

“Many supermarket and super center customers are already working hard to reduce their carbon footprint,” noted Scott Martin, director of sustainable technologies for Hill Phoenix. “CO2 technology gives them one more choice to help achieve their sustainability goals.”

Publication date: 11/02/2009