“I probably spend more time talking to people about industrial applications for CO2 than I ever have,” said André Patenaude, director – CO2 business development, Emerson Commercial and Residential Solutions, in a conversation with R744.com.

“Because of OSHA regulations for 10,000 lbs. or more of ammonia, they are not going to automatically default to ammonia, and they don’t want to use HFCs,” he added. “CO2 can fit a lot of these applications.”

Given this interest in CO2, Emerson, through its Vilter company, is preparing to offer transcritical and subcritical CO2 compressors for industrial end users. Its new 550 series of open-drive reciprocating compressors, to be released in the next two months, will accommodate capacities ranging 50 TR to 223 TR for low-temperature applications (-20°F evaporating and 23°F condensing). The compressors will come in two, four- and eight-cylinder models. The eight-cylinder model is on display this week at Vilter’s booth at IIAR’s 2017 Natural Refrigeration Conference & Heavy Equipment Expo in San Antonio, Texas.

The 550 series compressors have been running for the past year at Emerson’s Helix Innovation Center in Dayton, Ohio. “It’s pretty exciting stuff,” said Patenaude.

“CO2 can fit a lot of applications.

André Patenaude, director – CO2 business development, Emerson 

Emerson is also developing single screw compressors for medium-or low-temperature transcritical CO2 applications, ranging from 188 TR to 357 TR of capacity at 23°F evaporating and 95°F gas cooler out. The compressors will be offered in several displacements ranging from 128 CFM to 243 CFM. At the IIAR conference, the 160 CFM model is on display. The compressors can also be used in low-charge ammonia applications.

The smallest, an 188 TR screw compressor, provides almost eight times as much capacity as Emerson’s 25 TR unit, previously its largest offering. “If you’ve got one CO2 compressor that can do almost 200 tons for medium temperature, that changes the face of industrial refrigeration,” he said. Emerson will be seeking a field test site for the industrial screw compressor this year.

The screw compressors will include vapor injection, which can be used in place of parallel compression to improve efficiencies. “It takes the bypass flash gas vapor, and instead of sending it to suction like traditional systems, it sends the gas to the mid-compression part of the screw compressor,” said Patenaude, adding that this would eliminate the need for a parallel compressor.

“This is going to improve high ambient efficiency tremendously,” though not as much as the combination of a parallel compressor and an ejector, he said.

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