The development of new technologies such as ejectors is helping to improve the efficiency of CO2 transcritical refrigeration systems in warmer climates and cementing their position as market-ready alternatives to HFCs, especially for supermarket refrigeration, heard participants in the Gustav Lorentzen conference on natural refrigerants in Valencia last week.

The EU F-Gas Regulation bans the use of certain HFCs with GWPs above 150 in centralised and plug-in commercial refrigeration equipment from 2022. The consequent rise in prices of R404A and R507 (which are commonly used in supermarkets) is now driving companies to look for sustainable alternatives.

Boundary conditions like the warm climate of southern Europe had long been seen as a barrier to wider adoption of CO2, limiting the efficiency of these systems.

Giacomo Pisano of compressor manufacturer Dorin showed during his presentation in Valencia that thanks to innovations such as ejectors and parallel compression, CO2 systems deliver efficiency gains also in warm regions.He cited the example of a Carrefour store near Turin, in northern Italy. Amongst the novelties of its refrigeration system there are: 

  • 340 kW MT duty.
  • 66 kW LT duty.
  • Parallel compression.
  • Liquid and vapor ejectors.
  • Capable of operating in ambient temperatures of up to 45°C.
  • Heat recovery for both sanitary and ambient purposes.
  • Cooling module for air conditioning.

The system was assembled in 2015 to serve all the refrigeration, air conditioning and space heating needs of the supermarket.

Dorin calculated that by switching from a simple CO2 booster to a booster with parallel compression and liquid and vapour ejectors, an energy improvement of almost 30% is achievable. This makes the system more efficient than standard HFC-based units at any European latitude as well.

The return on investment from this innovative refrigeration system is just two years.

“It makes environmental and economic sense to invest in this technology,” said Pisano.

CO2 ejectors and energy efficiency in supermarkets were amongst the key topics of the Gustav Lorentzen conference, whose theme was solutions for warm climate conditions.

As Ekaterini Kriezi (Danfoss) argued, “not all ejectors are the same. One needs to look at the climate of each supermarket location to choose wisely the system to install”. 

In another presentation, Paride Gullo (NTNU) illustrated the findings of his research on CO2 technology in six Spanish cities.

The paper was presented at the 13th IIR Gustav Lorentzen Conference on Natural Refrigerants. The event took place on 18-20 June in Valencia and gathered more than 250 experts from all over the world. 

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