ATMO Europe: Carel Outlines CO₂ and Propane Commercial Refrigeration Evolution and Trends

Samuele Da Ros, Group Solution Marketing Manager for Food Retail Applications at Carel, outlined the evolution and market adoption trends of CO₂ (R744) and propane (R290) refrigeration solutions in commercial applications in a presentation at the ATMOsphere (ATMO) Europe Summit 2025.

The event, organized by ATMOSphere, was held November 24–25 in Padova, Italy. ATMOsphere is the publisher of NaturalRefrigerants.com. Carel, an Italy-based manufacturer of refrigeration components and controls, offers its products globally through over 30 subsidiaries and affiliates.

“Our history with natural refrigerants started over 20 years ago,” Da Ros said. “Through our work supplying components to OEMs, we’ve contributed to the installation of more than 20,000 centralized CO₂ systems, over 10,000 CO₂ condensing units and 5,000 semi plug-in cases operating on CO₂ or propane.”

Points highlighted by Da Ros included compact CO₂ condensing units, providing more solutions at lower prices, increased adoption of single–circuit architecture for large propane vertical cases and an increased design focus on CO₂ evaporator control.

Reduced costs: “In large commercial installations, CO₂ is the most used refrigerant in Europe,” Da Ros said, noting that ongoing technological improvements now allow CO₂ condensing units to be offered at “achievable prices” even for stores under 800m² (8,610ft²).

• The latest developments in CO₂ condensing units include double–stage compression and variable speed compressors, which provide ”flexible capacity to efficiently meet low– and medium-temperature [LT/MT] requirements in one single unit,” Da Ros said.
• When it comes to centralized CO₂ systems, he explained that racks smaller than 40kW (11.4TR) of cooling capacity now contain many of the features reserved in the past for larger units, including heat reclaim, two suction lines to enable booster designs and inverter-driven compressors on both suction lines.

New designs: Da Ros reports that in the past three years, large vertical propane cases have started adopting single–circuit architecture, with variable speed compression.

• In 2023 Europe accepted the international safety standard IEC (International Electrotechnical Commission) 60335-2-89, which was updated in 2019, to raise the flammable refrigerant charge in a single circuit to 500g.
• The new design simplifies the unit, reducing capital, operating and maintenance costs.
• “There is some reluctance to leave the known for the unknown, but the use of single–circuit propane cases with up to 7kW [2TR] of MT cooling capacity or 3kW [0.85TR] of LT is picking up,” Da Ros said.

Next step: “Our latest frontier involves working to optimize and embrace semi-flooded CO₂ evaporators,” Da Ros said.

• Running on extremely low superheat brings complexity, according to Da Ros, but it also provides efficiency benefits, with higher evaporating temperatures requiring smaller evaporators.
• “With the proper algorithms, we can control it,” Da Ros said, making CO₂ refrigeration even better.

Quotable: “The common thread in the evolution of these systems is to make them easier to install, use and maintain in real–world conditions,” Da Ros said, adding that in Europe, over 80% of Carel’s business supplying food retail refrigeration products involves natural refrigerant components.

“The common thread in the evolution of these systems is to make them easier to install, use and maintain in real–world conditions.”

Samuele Da Ros, Group Solution Marketing Manager for Food Retail Applications at Carel