Two propane chillers provide both cooling power to the subcooling system after the CO2 transcritical gas cooler and air-conditioning during summer time in a METRO Italia Cash and Carry superstore in Padova, North-Eastern Italy.
This installation is part of the German-headquartered wholesaler’s attempts to phase out f-gases from its stores by 2030, replacing them with natural refrigerants. “The project developed in Padova is an important part of Metro’s [F-Gas Exit] Program from HFCs to natural refrigerants,” METRO Italia Cash and Carry’s energy manager, Roberto Scarano, told Accelerate Italy.
The Padova METRO Cash and Carry store opened in 1997. At the end of the existing equipment’s lifecycle, METRO switched to a new transcritical CO2 system in 2016. The store’s net sales area is around 5,800m2.
The transcritical CO2 system cools all the store’s display cabinets and cold storage facilities. “The cooling system is composed [of] two CO2 racks: one […] low and medium temperature with parallel compression and booster system. The other cooling [rack] [is set for] neutral temperature [also using] parallel compression,” Scarano explains.
What makes this store so unique? Two propane chillers, from Italian manufacturer Euroklimat, serve two different purposes: first, providing “cooling power to [the] subcooling system after the [CO2 transcritical] gas cooler,” and second, air conditioning the store during the hot Italian summer, he says.
The propane chillers are part of an indirect system that provides the air conditioning and the subcooling. No refrigerant is circulated in the store.
“This solution increases the efficiency of the cooling system. We also optimise the equipment installed and the spaces used, because these chillers have a double function,” he says.
Together the chillers provide a cooling capacity of 510 kW, according to Euroklimat’s product developer, Giulia Fava, who spoke at ATMOsphere Europe in Berlin, Germany about the project in September 2017.
Steps must be taken to ensure that the chillers comply with local safety standards. “You need a provision from the fire department [in Italy] and you need to conduct an in-depth analysis” to install this type of equipment, Fava said.
The analysis recommended that METRO install a safety grid around the propane chillers in the Padova store, within which only authorised people can venture.
The chillers also have compressors and pressure switches that comply with the EU directive on controlling explosive equipment (known as ATEX), and a gas detector for leakage purposes.
METRO Italia Cash and Carry will replace HFCs with a CO2 transcritical system in one more store in 2018.
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