USA: Trane claims to have surpassed the US Department of Energy requirements in its challenge to improve the performance and energy-efficiency of cold climate heat pumps.
The US DOE’s Residential Cold Climate Heat Pump (CCHP) Challenge, announced last year, is designed to accelerate the market’s shift to more-efficient, cold-climate domestic heat pumps.
One of six manufacturers to have accepted the challenge, Trane says its heat pump will begin field trials this month after outperforming in laboratory tests in extremely cold temperatures
Tests carried out on Trane’s CCHP prototype at the DOE’s Oak Ridge National Laboratory are said to have performed in temperatures as low as -23ºF (-31ºC), surpassing the mandatory -20ºF (-29ºC) DOE requirement.
“When tested at the Oak Ridge National Lab Facility, our prototype pushed the limits of the testing with high performance even as temperatures moved beyond the trial scope,” said Katie Davis, Trane Technologies’ vice president of engineering and technology, residential HVAC. “To stop this Trane unit, they had to manually cut the power,” she added.
The DOE Challenge stipulates the use of a refrigerant with a GWP of no more than 750 under AR4. While information on the Trane prototype is limited, the company told the Cooling Post that it was using R454B, the A2L refrigerant blend with a GWP of 467.
A Trane spokesperson added: “There are several approaches to improving a heat pump’s performance in cold climates, including but not limited to cascade refrigeration systems, various forms of multi-stage compression, vapour injection, and liquid injection. The optimal solution will consider the trade-off between customer needs, product cost, operational efficiency, reliability, and technology readiness. It’s all about maximising value for our customers while meeting their comfort needs.”
In June, manufacturing rival Lennox claimed to be the first to have achieved the challenge’s standards, delivering 100% heating at 5°F (-15ºC) at double the efficiency, and 70% to 80% heating at -5°F and -10°F (-20ºC and -23ºC). These performance and efficiency figures were also verified at the DOE’s Oak Ridge National Laboratory.
Carrier, another company taking up the challenge, also announced this week that it was pleased with the lab performance of its prototype unit and was to begin field trials.
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