More than 150 stores across Europe, the Middle East and Australia have now installed Epta’s Extreme Temperature Efficiency (ETE) technology, according to David Wirth, Product Manager of Power Packs at the Italian OEM.
With ETE, which was launched at EuroShop in 2020, Epta has integrated a subcooling unit into its transcritical CO2 (R744) systems to help boost efficient operation in high ambient temperatures. The subcooling unit consists of a dedicated compressor that is only turned on once a certain ambient temperature is reached.
Wirth shared details of Epta’s ETE installations during his presentation in a refrigeration session at the ATMOsphere (ATMO) Europe Summit on natural refrigerants. The conference took place November 15–16 in Brussels and was organized by ATMOsphere, publisher of R744.com.
Reliable system in 50°C
In high ambient temperatures, the production of flash gas in a transcritical CO2 system increases, reducing the amount of liquid refrigerant in the system, explained Wirth.
“In the end, there’s not enough liquid refrigerant left in the system to maintain the set temperature,” he said. “Compressors are running at maximum capacity, but they’re just running flash gas in a circle. We really need to look at the performance of our transcritical CO2 systems in these very warm and hot ambient conditions.”
Compared to parallel compression, which uses similar components, ETE works by avoiding the production of flash gas rather than trying to get rid of flash gas efficiently, which is how parallel compression is designed to overcome this issue.
“With ETE, in the end, you have a reliable and energy efficient system in 50°C [122°F],” said Wirth. “There really is no limit with ambient temperature any more; it just depends on the size of the subcooling compressor.”
“With ETE, in the end, you have a reliable and energy efficient system in 50°C [122°F]. There really is no limit with ambient temperature any more; it just depends on the size of the subcooling compressor.”David Wirth, Epta
ETE is more effective than parallel compression with excellent COP and an increase in liquid CO2 in the system, meaning that its evaporators can run at 100%, he added.
73% reduction of flash gas
In Bologna, Italy, at a 6,500m2 (70,000ft2) supermarket with a medium-temperature (MT) cooling requirement of 150kW (42.6TR), Epta’s ETE technology reduced the refrigeration system’s flash gas production by 73%.
In turn, this reduced the energy consumption of the system’s MT compressors by 30% and the overall pack by 14% during periods of high ambient temperatures – around 41.5°C (106.7°F).
Similarly, at a 1,500m2 (16,100ft2) store in Ellenbrook, Australia, where summer temperatures frequently exceed 35°C (95°F), Epta’s ETE technology reduced its system’s flash gas production by 81%. This resulted in a 35% reduction in the MT compressor’s energy use, and an 18% reduction on the system’s total energy use.
According to data shared by Epta, a transcritical system with ETE technology can be 40% more efficient than a standard transcritical system in ambient temperatures of 40°C (104°F). At lower temperatures, performance is still improved by ETE but not as significantly. For example, at 27°C (80.6°F), ETE boosted system efficiency by 15%.