The new Zero Zone CO2 condensing unit
The new Zero Zone CO2 condensing unit. Photo via Zero Zone.

Zero Zone Launches Transcritical CO2 Condensing Unit and Propane Chiller for U.S. Market

Both products come in a modular design, with the CO2 unit providing 3‒12TR and the propane chiller 3‒5TR.

U.S. OEM Zero Zone has launched a new transcritical CO2 (R744) condensing unit and a propane (R290) chiller for the U.S. market, with both products offered in a modular design to simplify installation in retail and small industrial spaces.

The launch took place at the 2024 IIAR Conference, held March 24‒27 in Orlando, Florida.

“Given the AIM [American Innovation and Manufacturing] Act and all the changes we have, these [units] are part of an evolution of our natural refrigeration products,” said John Collins, Industrial Sales Manager at Zero Zone, in a presentation.

Both CO2 condensing units and propane chillers are relatively new to the U.S. market, although both pieces of equipment have carved out a small foothold in Europe. Of the estimated 68,500 supermarkets in Europe that use CO2 refrigeration, 8,500 are equipped with CO2 condensing units according to data from ATMOsphere’s 2023 natural refrigerants market report (p.15); ATMOsphere is the publisher of The report estimates that as of December 2023, there were an estimated 5,000 hydrocarbon chillers in use at industrial sites in Europe (p.70).

U.S. OEM Hillphoenix released a transcritical CO2 condensing unit for the North American market designed to provide cooling for cabinets and cold rooms at smaller footprint supermarkets in 2022, and in 2021, U.S. OEM M&M Carnot released an industrial air-cooled CO2 condensing unit.

CO2 condensing unit

The new transcritical CO2 condensing unit currently comes in four sizes, offering refrigeration capacities from 3 to 12TR (10.5 to 42.2kW) in an operating range of 10 to 30°F (−12.2 to −1.1°C). Collins noted that combining the units provides capacities of up to 50TR (175.8kW) for supermarkets and small industrial applications.

The unit operates in ambient temperatures from −20 to 105°F (−28.9 to 40.6°C) with a 130bar (1,885psi) pressure rating on the high side and a 90bar (1,305psi) rating on the low side.

Using 90bar on the low side removes the problem of releasing refrigerant charge in a power outage, said Dan O’Brien, President of Zero Zone, in an exclusive interview at the expo with Marc Chasserot, Founder and CEO of ATMOsphere.

“We can build the CO2 unit with adiabatic or dry gas cooling,” O’Brien added, making it fit for use in many climates with a “massive” ambient temperature range.

As a modular plug-and-play condensing unit, it is a “nice fit” for end users and contractors with little CO2 experience, Collins said. “It’s a simple, low-cost installation, with minimal field piping,” he added, indicating that its light weight allows installation on most rooftops without added supports.

According to O’Brien, the unit uses a Copeland variable-speed scroll compressor that is new to the U.S. market.

“The variable speed compressor supports energy efficiency by modulating capacity to the demand,” Collins said.

“The unit’s flexibility makes it applicable to more than supermarkets and small cold storage spaces,” O’Brien said, indicating that they could put it on a process chiller with a heat plate exchanger.

Collins said the company plans to broaden the range to include more low-temperature operating options in the coming months.

Propane chiller

The company’s propane chiller, designed for outdoor installation, provides 3‒5TR (10.5‒17.6kW), depending on the model, with a charge of roughly 1.7lbs (771g) of propane. According to Collins, connecting units can provide up to 30TR (105.5kW).

As a water-cooled chiller using a mechanically driven water control valve for condensing, the unit supplies glycol at −5 to 40°F (−20.6 to 4.4°C) in ambient temperatures ranging from −20 to 115°F (−28.9 to 46.1°C).

Current regulations limit the propane charge of indoor installations of closed appliances to 300g (10.6oz).

“These propane units are an intermediate step, going from the tiny charges approved for indoor installations to a larger chiller,” Collins said, adding that the design includes ATEX [explosive atmosphere] components with a semi-hermetic Dorin compressor.

At the IIAR Conference, O’Brien told Chasserot that the unit uses a Class 1, Division 2 electrical panel, pressurized with inert gas, to “take care of flammability risks” from sparking electricity.

O’Brien said that local jurisdictions and fire marshalls would have to provide their approval before end users could install the chiller, which he said could be used for process cooling applications such as cooling cold rooms or cases. “It’s doable,” he added, citing compressed propane currently used in other process spaces, including the oil and gas industry.

According to Collins, the propane chiller was brought to the show to “start some conversations” as the U.S. begins phasing down HFC production. “As an A3 refrigerant, propane needs to be appropriately applied, but it is a great natural refrigerant option.”

More companies are adopting natural refrigeration systems as they seek to comply with regulations and appeal to an environmentally concerned public, Collins noted.

“At Zero Zone, in the past three to five years, we have seen a move in the industry,” Collins said. “We have gone from the bulk of our production being HFC/HFO refrigerants to 50% or more of our production floor regularly being natural refrigerants.”

Headquartered in North Prairie, Wisconsin, Zero Zone was established in 1961 and manufactures industrial and commercial refrigeration systems and refrigerated display cases. The company also provides CO2 training monthly at its Ramsey, Minnesota, facility for customers and contractors.

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