CO2 is becoming a growing refrigeration add-on option for cold-storage and food processing operators that are expanding their ammonia-based operations, said an account executive for M&M Refrigeration, a leading supplier of ammonia/CO2 cascade systems, in an exclusive interview yesterday.

The CO2 in these scenarios is used as the cooling agent, with ammonia serving to condense the CO2 in what is known as an ammonia/CO2 cascade system.

Since 2004, M&M, based in Federalsburg, Md., has installed more than 55 ammonia/CO2 systems in North and Central America and Southeast Asia, said Todd Donohoe, the account executive, in an interview yesterday at the Global Cold Chain Expo at McCormick Place in Chicago.

“We say, ‘Have you thought about CO2, because it can save you money in the long run.’”

Todd Donohoe, M&M Refrigeration

Asked about the growth of the market for ammonia/CO2 systems, he said M&M cold-storage operators planning to add a frozen room to an existing facility may initially inquire about a standard single-stage or two-stage ammonia system. “We say, ‘Have you thought about CO2, because it can save you money in the long run,’” said Donohoe. “That’s where the conversation usually starts.”

When installing CO2 in an expansion, M&M sometimes uses the existing ammonia engine room to condense the CO2 in a cascade heat exchanger, and sometimes adds additional ammonia equipment. “If there’s no room in the existing engine room, we can do a self-supporting skid outside,” he said.

In a current expansion scenario, M&M is converting the entire plant to CO2, using ammonia only in the engine room to condense the CO 2, said Donohoe, who declined to name the operator without its permission. “We are repurposing the existing ammonia screw compressors, using different motors, and adding CO2 reciprocating compressors.”

CO2/NH3 cascade technology is a compelling option for industrial operators employing blast or spiral freezers because it uses smaller line sizes than ammonia, is easier to install, and reduces the ammonia charge – “all the buzzwords,” said Donohoe. Moreover, the cascade systems are up to 35% more efficient than a two-stage ammonia system at -58°F saturated suction temperature, he noted.

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