Swiss OEM Biaggini Frigoriferi has installed two reversible transcritical CO2 chillers in a shopping mall that supply both air conditioning (AC) and heating, one of the first systems of its kind, the company said.

The chillers replace an oil boiler and an old HFC cooling system in the mall, which is located close to the airport in Lugano, Switzerland, and run by Swiss retailer Migros.

The new chillers are called ReversinGreEnergy because they are “totally reversible,” explained Luca Rossi, Project Manager with Biaggini Frigoriferi. They can function as both heat pumps and chillers, “satisfying heating and cooling needs at the same time.” This is the first installation of the ReversinGreEnergy system.

The commissioning of the system was in early May, and “everything has been running smoothly, more so than our expectations,” Rossi said.

The two chillers are identical, and deliver a total of 600kW (171TR) cooling and 500kW (142TR) heating. The only difference between the two units is that one of them is connected to a CO2 evaporator that cools the technical room.

The chiller units operate at 120bar pressure on the high pressure side, and 80bar on the low pressure side. The ReversinGreEnergy chillers deliver 8°C (46.4°F) water in cooling mode, with a 14°C (57.2°F) input temperature. In heating mode the water temperature is 27°C (80.6°F) and the outlet temperature is 37°C (98.6°F).

Double coils

A unique feature of the new chillers are the double coils, where the gas cooler and evaporator coils are separated, ensuring the “best performances in both heating and cooling mode,” while at the same time optimizing the defrost cycle, said Rossi.

Another benefit to the new system is that it can easily be stopped and restarted to suit the heating/cooling needs of the mall, providing both energy and cost savings. “They can stay stopped for several weeks without the problem of pressure increasing, and the units are switched on only when an external digital signal tells them that the building needs heating or cooling capacity,” Rossi explained.

Eliwell supplied all the electronics for the system; other component suppliers include Dorin, LU-VE, Alfa Laval, Castel, Refrigera and Temprite.

The Lugano installation is the first using the ReversinGreEnergy chillers, but it won’t be the last. “We are already planning the next installations, probably during this year,” Rossi said.

Migros is a pioneer in the adoption of natural refrigerants, having installed its first transcritical CO2 system in 2009. In 2019, Migros installed its first integrated CO2 system, also delivered by Biaggini, which supplies refrigeration, winter space heating and summer air-conditioning requirements for a store in Riazzino, Switzerland.

“Everything has been running smoothly, more so than our expectations.”

Luca Rossi, Biaggini Frigoriferi

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