First U.S. retail test of modulating unit is in the offing, offering 10%-20% energy reduction for transcritical CO<sub>2</sub> system.
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Global component and controls manufacturer Danfoss regards its energy-saving CTM multi-ejector to be “a very important development” that allows transcritical CO<sub>2</sub> systems to be “more efficient than HFC systems in all climates,” said James Knudsen, segment manager, food retail for Danfoss.
Danfoss has about 30 test installations of the gas ejector in Europe and Africa and is in the process of running its first U.S. retail installation in the Atlanta area, said Knudsen, adding “All major OEMs are testing in in their labs.”
Notably the multi-ejector contains up to six ejectors of varying sizes, allowing it to modulate to different ejectors depending on load demands.
Working with a parallel compressor in a transcritical CO<sub>2</sub> system, the ejector saves between 10% and 20% on energy consumption (depending on the ambient temperature) compared to a conventional booster transcritical system, he said. “The hotter it gets, the more an ejector saves.” Moreover, it “reduces compressor power to the point where in large systems you could eliminate a compressor, which helps to reduce first cost.”
In the North America, parallel compression in transcritical systems is just beginning to be used in the field, Knudsen noted.
The Danfoss ejector, which won the 2017 AHR Expo Innovation Award in the refrigeration category, is essentially a sold-state pump with no moving parts that saves energy by increasing the pressure of CO<sub>2</sub> gas being compressed by a low-HP parallel compressor, thereby reducing overall compressor load. “Instead of the parallel compressor handling 40% of the gas, it handles 80% of the gas,” said Knudsen. “That’s where you save energy. Without an ejector, the parallel compressor doesn’t get as much bang for the buck.”
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