Creative Thermal Solutions CTS), an Urbana, Illinois (U.S.)-based HVAC&R research company, has developed a small, low-cost CO2 (R744)-based condensing unit designed for commercial applications.
The prototype, with a cooling capacity of about 1.6kW (0.45TR), was developed as an example of what could be achieved in a low-cost CO2 condensing unit with the same efficiency and capacity as a comparable R448A unit, explained Stefan Elbel, CEO of CTS. Elbel is also Research Assistant Professor in the Department of Mechanical Science and Engineering, and Co-Director, Air Conditioning and Refrigeration Center, at the University of Illinois at Urbana-Champaign.
The prototype design was for medium-temperature applications, but a similar design could be used for low-temperatures as well, said Elbel.
CTS is open to collaborating with manufacturers in a commercial product, said Elbel. “It’s a relatively small system to start with, but it might spark some more interest in a low-cost-type system for larger capacities.” CTS is already working on a scaled-up version of the unit, he added.
The initial prototype would have immediate application to a walk-on cooler, for which CTS has also designed a CO2-optimized evaporator. The capacity of the prototype would be low for typical commercial display cases, but a larger-capacity version would be suitable for display case systems or larger walk-ins, Elbel said.
Converted R448A unit
In developing its prototype, CTS converted a condensing unit using R448A to an “extremely low cost” CO2 unit with small hermetic rotary compressors but no “fancy” components like ejectors, said Elbel.
“We were able to achieve, after only a little bit of optimization, the same efficiency and capacity as the R448A unit,” he added. The optimization related to charge, pressure and fans.
Elbel noted that the of the prototype CO2 unit was designed for an indoor rating, with conditions at 90°F (32.2°C), and the functionality of the system was tested up to 110°F (43.3°C).
Want to find out more, or have something to say about this story? Join the ATMO Connect network to meet and engage with like-minded stakeholders in the clean cooling and natural refrigerant arena.