The system – in a 6,800m2 hypermarket in the suburb of Cambuci, São Paulo – is the second CO2 transcritical installation in Brazil. The first was commissioned by the Carrefour Group for an Atacadão-branded cash & carry store in Atibaia, São Paulo state, which opened on 16 June. Other systems run in test labs built by Bitzer and Eletrofrio, but Carrefour’s are the first in the field.
“We decided to import the technology. Nobody in Brazil is currently producing CO2 transcritical systems. Locally-available components for CO2 transcritical systems are also lacking,” Martini said.
Carrefour is determined to succeed there. Martini is convinced that installing CO2 transcritical systems in Brazil will help to raise awareness of the technology’s performance benefits. “The process was smooth thanks to Plotter Racks, the system installer for both stores. We also have a maintenance contract with them,” he said.
The Cambuci store is fitted with two parallel compression CO2 booster transcritical racks. Each rack has a capacity of 100 kW (at -8°C) for medium temperature users and a capacity of 45 kW (at -30°C) for low temperature users.
System manufacturer Advansor – which works with Plotter Racks in the Brazilian market – assembled the racks in Denmark before shipping them to Brazil. The heat exchangers (Thermofin) were also imported, while Danfoss provided the rack controllers. Upon the racks’ arrival in Brazil, Plotter Racks assembled the gas coolers: adding their adiabatic ‘Breeze’ system.
The adiabatic technology restricts water consumption to the required amount, reducing the air inlet temperature of the gas cooler and thereby improving system performance and reliability.
The system’s steel high-pressure discharge lines can withstand pressures of up to 120 bar, while its liquid and medium-temperature suction lines (thick copper) and low-temperature suction lines (copper) are designed for pressures of 52 bar and 30 bar respectively.
Subcritical CO2 systems have a more established track record in Brazil, with Plotter Racks and Eletrofrio building them locally. “Knowledge of subcritical CO2 is already pretty good, but knowledge of transcritical should be improved for sure,” Martini said. He is nonetheless confident that “things are moving” towards local production of systems and components.
Plotter Racks came to Denmark to receive advance training from Advansor, while Danfoss was on site to assist with the Cambuci installation. Arneg provided the display cases for the Cambuci store, while EBM Papst provided the fans for the evaporators and gas coolers.
“After a year, we can draw conclusions.“Carrefour’s Paolo Martini
For Carrefour, energy performance is just one part of the picture: it is also about reducing system costs. Once local awareness of the technology improves, then “assembling the racks locally rather than importing them would help” in this regard, Martini stresses.
Martini stresses that is too early to commit to CO2 transcritical solutions for all the Carrefour Group’s Brazilian locations. System performance in the Cambuci and Atibaia stores will be monitored for twelve months, compared to other Brazilian shops with similar capacity systems based on HCFCs, HFCs and HFC-CO2 cascades.
“You import the technology and you train the Carrefour staff. People learn how to deal with transcritical CO2, and we assess how the system is performing. After a year, we can draw conclusions,” Martini declared.
The Atibaia and Cambuci stores represent another milestone in the evolution of transcritical CO2 technology – and in the Carrefour Group’s commitment to reducing greenhouse gas emissions and energy consumption.