Using standard off-the-shelf refrigeration compressors and components, U.S.-based OEM Flow Environmental Systems manufactures CO2 (R744) heat pumps that provide heating, cooling or simultaneous heating and cooling.
The heat pump, dubbed ANSWR, offers capacities from 15‒120TR (53‒422kW), with units using air or water heat sources. Outlet water temperatures range from 90‒180°F (32‒82°C) for heating and 38‒75°F (3‒23°C) for chilling, with lower temperatures available via a glycol mix.
For heating, a CO2 heat pump is 20‒40% more efficient than the synthetic blend R454B in ambient temperatures ranging from −10 to 110°F (−23 to 43°C), Sean Jarvie, the CTO of Flow, told Marc Chasserot, ATMOsphere’s CEO and Founder, in a recent interview. ATMOsphere is the publisher of NaturalRefrigerants.com.
“When it comes to cooling, people complain that [CO2] is less efficient at peak loads, but that represents only 1% of operating conditions,” Jarvie said. “For 99% of its chilling operation, CO2 is on par with R454B, and adding an adiabatic gas cooler makes it as efficient if not slightly more so than the best cooling solutions on the market.”
At its headquarters in Rogers, Minnesota, Flow can simulate local low temperatures down to −20°F (−28°C) and highs up to 135°F (57°C). According to Jarvie, the lab setup allows the OEM to produce desired output temperatures using real-time data to control variable primary pumps and mixing valves.
Pilot projects
Last month, ANSWR was one of three natural refrigerant heat pumps named as a finalist for New York’s Empire Technology Prize, which it entered with New York-based HVAC design and implementation firm Ambient Enterprises and contractor Gil-Bar. The competition seeks to advance low-carbon heating and distribution technology for use in high-rise commercial and residential building retrofits, with finalists matched with in-state property owners for pilot projects.
Flow is also involved in a California project to replace gas heating and hot water heaters with CO2 heat pumps. In particular, the project seeks to advance heat pump operations in large commercial buildings to provide domestic hot water, heating and cooling.
“With an air interface, we can use an adiabatic cooler to support CO2 heat pump operation in scorching temperatures,” Jarvie said. “We can also handle low ambient temperatures that no other heat pump [on the market] today can touch.”
Don’t reinvent the wheel
Jarvie explained that Flow seeks to move CO2 into the HVAC space by using technology developed in industrial and commercial refrigeration over the past 20 years. “We can optimize existing components for HVAC applications to provide high-temperature cooling and low-temperature heating at a price point that financially makes sense,” he said.
With two patents pending, Flow says its CO2 heat pump technologies increase efficiencies and broaden the ambient temperature operating range.
According to Jarvie, the company has installed cooling-only heat pumps in a Southern California project, noting that operational data from the study will be available in a couple of months.
