The Convergence of Ammonia/CO2 Technologies

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In my previous blog, I explained why CO₂ and ammonia (aka NH₃) refrigerant technologies are crossing over into each other’s traditional market spaces, i.e., CO₂ making its way into industrial settings and low-charge ammonia systems in use in commercial applications.

 As regulatory compliance concerns and sustainability objectives drive end users toward natural refrigerants, original equipment manufacturers (OEMs) are responding with new innovations that draw from traditional CO₂ and ammonia architectures.

Let’s look at some innovations that are indicative of this convergence.

NH₃/CO₂ cascade — Ammonia in commercial refrigeration

Owners of large (+100-ton) commercial HFC systems are now considering implementing smaller, lower-charge NH₃/CO₂ cascade systems. In turn, some industrial OEMs are expanding their product portfolios to target the emerging niche for natural, energy-efficient systems in commercial refrigeration. These NH₃/CO₂ cascade systems are designed to operate with very low charges of ammonia (100 pounds or less) on the high side of the refrigeration cycle (in a remote location, e.g., the roof) to chill the CO₂ sent out to the cases in a store.

 CO₂ transcritical booster — CO₂ in industrial refrigeration

CO₂ offers a documentation-free refrigeration alternative to long-time operators of large-charge ammonia systems. Commercial OEMs with CO₂ expertise are answering the call for CO₂ transcritical booster systems, which have proved viable in cooler regions. This system utilizes several compressors in parallel to meet the desired cooling requirement. CO₂ blast freezers are also effective in low temperatures, especially below -40 °F.

 Smaller-platform applications for ammonia

Both commercial and industrial operators with smaller facilities have a variety of low-charge ammonia options from which to choose to meet their cooling requirements and sustainability goals:

• • NH₃low-charge centralized — this remote, distributed architecture is designed to reduce the liquid line length and subsequent refrigerant charge.
  • NH₃direct expansion — available in distributed or remote varieties, this system requires the circulation of much less refrigerant.
  • NH₃chiller with pumped CO₂ secondary — ammonia chills CO₂ (volatile brine), which is then pumped into the refrigerated areas.
  • NH₃chiller with pumped CO₂ secondary, plus CO₂ cascade — combines an NH₃ chiller that provides the medium-temperature load via a CO₂ secondary design, plus a CO₂ cascade system for the low-temperature side.

 This convergence also proves that operators of commercial and industrial facilities have more in common than they realize. Both are trying to balance capital expenditures, total cost of ownership and sustainability objectives in their selection of refrigeration systems. So, the blurring of lines between CO₂ and ammonia technologies in these markets is ultimately beneficial to all involved.

 Read the full Accelerate America article on the convergence of ammonia and CO₂ technologies [pg.16].