High-ambient-ORNLUSA: A number of lower GWP R410A alternatives are said to have shown significant potential in high ambient split-system tests conducted by Oak Ridge National Laboratory.

The latest ORNL report that updates previous tests carried out on R22 replacements, looks at four R410A alternative refrigerants: the single component HFC refrigerant R32,  Arkema’s ARM-71A, Chemours’ DR-55, Honeywell’s L-41 (R447A) and Mexichem’s HPR-2A.

R32 was the only refrigerant that showed consistently better capacity and efficiency than R410A. However, as previously observed, the potential negative aspect of R32 is its higher discharge temperature. ORNL tests are said to have shown this to be 12-21°C higher than R410A, a characteristic which ORNL observes might negatively impact compressor reliability.

DR-55 and HPR-2A had higher COPs than the baseline and matched the capacity of the baseline at both the hot and extreme test conditions. R447A and ARM-71a had lower cooling capacity than the baseline at all ambient conditions. R447A showed system efficiency improvements over R410A at high ambient temperatures, while ARM-71a, exhibited similar efficiency to R410A at all test conditions.

The tests were conducted on a soft optimised Carrier mini-split with a cooling capacity of 5.25kW. The ORNL notes that efficiency and capacity of the alternative refrigerants could be expected to improve in products optimised by the manufacturers for specific use with the new refrigerants.


Pub59157-(1)-182R22 update

The final report also updates similar tests carried out on R22 alternatives by including results for propane (R290). In line with other tests, R290, although classed as a flammable A3 refrigerant, exhibited consistently higher efficiency compared to R22. However, it failed to match the cooling capacity of the baseline system.

Previous tests on four other HFC/HFO R22 alternatives, all A2L refrigerants, were found to deliver a lower performance than R22, both in terms of COP and cooling capacity.  These were Chemour’s development blend DR-3, Honeywell’s N-20B and Solstice L20 (R444B) and Arkema’s ARM-20B.

Based on the assumption that manufacturers can address performance losses, the increased discharge temperatures and safety concerns associated with flammable alternatives, the ORNL concludes that all the low-GWP alternative refrigerants “may be considered as prime candidate refrigerants for high ambient temperature applications”.



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R32 passes high ambient test – September 16, 2015
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