Cold storage warehouse operator Americold has deployed single-stage compressors in its new 542TR (1.9MW) transcritical CO₂ (R744) warehouse in New Brunswick, Canada, according to Phillip Walker, General Manager at TechnoRef4, the engineering firm that designed the system.

Americold opted for a simple design given the mild Canadian climate, Walker noted in a presentation at ATMOsphere America Summit 2026, adding that this marks the logistic provider’s first foray into transcritical CO₂ refrigeration. Giacomo Pisano, CO₂ Compressors Business Development Manager at Dorin, joined Walker at the conference to outline the operation of single-stage compressors. The event, organized by ATMOsphere, publisher of NaturalRefrigerants.com, took place June 2‒3 in Tarrytown, New York.

The design uses semi-hermetic CO₂ compressors to serve both low- and medium-temperature (LT/MT) loads, enabling flexible freezer storage between −19 and 25°F (−28 and −4°C). The grand opening of the new warehouse took place on June 18, according to Americold.

“In our dual temperature design with a split suction header, we removed the booster and all those controls, providing 18.2% CAPEX cost savings for the customer,” Walker said, adding that the simplified single-stage layout also eases system commissioning and maintenance.

The setup: Located at Port Saint John, the 140,000ft² (13,000m²) warehouse includes a 35,000ft² (3,250m²) loading dock maintained at 34°F (1°C) and handles a throughput of roughly 3.5 million pounds (1.6 million kilograms) of goods per hour, according to Walker.

• Two nominal 557HP packs, manufactured by Canadian-based Ceptek, provide both MT and LT refrigeration, each delivering 271TR (950kW) of capacity. Each pack includes nine six-cylinder compressors.
• The design includes hot-gas defrost for LT and MT operation, a heat-recovery module with a glycol-pumping skid and adiabatic gas coolers for operation in ambient temperatures above 95°F (35°C).
• The MT loading dock operates with a COP of 6.39, while the LT freezer operates with a COP of 3.27 during daytime active loading. However, when accounting for 5.502MMBtu/h (458TR/1.6MW) of reclaim heat capacity, the site achieves a combined useful COP of 3.41.

Up to the task: In cold-climate applications, single-stage CO₂ compressors can operate at evaporating temperatures as low as −20°F (−29°C) while withstanding transcritical pressures of up to 1,250psi (80bar), according to Pisano.

• In addition, the oil sump temperature remains “pretty low” at around 162°F (72°C), resulting in a residual viscosity of 16cSt (centistrokes), which Pisano said indicates adequate lubrication despite high-pressure operation.
• “The message is that single-stage compressors are capable of handling LT conditions, backed by a large safety margin,” Pisano added.

End user wanted: Although the CO₂ system generates 5.502MMBtu/h of heat recovery capacity, the warehouse only uses 0.7MMBtu/h (58.3TR/205kW), leaving 4.8MMBtu/h (398.1TR/1.4MW) available for outside use.

• “To maximize full heat reclaim, we are looking to deliver that heat to neighboring sectors either for district heating or process applications,” Walker said.

Quotable: “In this kind of application, you don’t need a booster, and you can do a single-stage suction group with way less complexity,” Pisano said, adding that Dorin’s external discharge plenum keeps the compressor outlet temperature below 300°F (149°C).

“In our dual temperature design with a split suction header, we removed the booster and all those controls, providing 18.2% CAPEX cost savings for the customer.”

Phillip Walker,
General Manager at TechnoRef4