Efficiency Improvements of CO2 Transcritical Systems

CO2 transcritical systems commercial-refrigeration compressed air energy storage

Ejectors seen as way forward for CO2 transcritical  

R744.com, June 19, 2017

Italy-based manufacturers Dorin (compressors) and CAREL (controls) both see ejectors improving the efficiency of CO2 transcritical systems in warm climates.

At ATMOsphere America 2017 in San Diego, California, Italy-based Dorin, a compressor manufacturer, and CAREL, a controls manufacturer, grappled with how they can push the North American market towards adopting CO2 transcritical systems for all climate conditions.

Giacomo Pisano, technical sales manager at Dorin, explains that the payoff or energy savings using CO2 transcritical technology compared to R404A can be great in milder northern climates.

The systems can deliver energy savings of up to 19,000 euros a year in most northern areas, Pisana said. In warmer climates, however, they can cost up to 11,000 euros more to run than an R404A if no ejector is installed. This would make it difficult for end users to consider installing CO2 systems in warmer climates, he argued

He showed that installing an ejector eliminates this cost and can even save end users 1,000 euros a year compared to R404A even when temperature reach up to 45oC.

“The performance of CO2 is affected by warm climates – ejectors and [brushless DC electric motor] BLDC technology can help to address this,” explained Nicola Pieretti of CAREL, who developed the EmJ modulating ejector with Carrier UTC.

Europe – an ejector success story

Ejectors have already seen some success. “In Europe, there are around 200 CO2 transcritical booster systems running with either gas or liquid ejectors,” Pisano said.

“We’re also seeing a lot of interest in small condensing units in the European market, a trend which may soon come to the United States, and there’s room for ejectors also in this application,” added CAREL’s Pieretti.

Dorin’s Pisano agreed that Europe had been a leader in this regard.
He believes gas and liquid ejectors need to be installed in combination to avail of these energy efficiency reductions.
Ejectors are only just beginning to make inroads into the United States. “[Hillphoenix] recently installed an ejector with parallel compression at a Sprouts store in Woodstock, GA,” Jeff Newel from Hillphoenix told the audience.
This is the first supermarket in North America to use an ejector, according to Newel.

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