USA: Further tests of low GWP alternatives to R410A in air conditioners have again shown good results at high ambients.
The latest results, from phase ll of AHRI’s Low-GWP Alternative Refrigerants Evaluation Programme, compared the performance of R32 and Chemours’ development refrigerants DR-55 and DR-5A in soft optimisation tests against baseline R410A.
The three alternatives all offer considerable lower GWPs compared to R410A’s GWP of 2088. R32 has a GWP of 675, DR-5A slightly higher at 698 and DR-55 the lowest of the three at 466. All are A2L “mildly flammable” gases but Chemours has recently claimed that DR-55 has a lower burning velocity than the other two.
The latest tests were performed on a Trane Precedent 14 kW rooftop heat pump at Ingersoll Rand/Trane’s La Crosse Development Laboratory in La Crosse, Wisconsin.
The unit was run at the rating conditions specified in AHRI Standard 210/240 for both cooling and heating modes. In addition, the unit was run in cooling mode at ambient temperatures from 18°C to 52°C.
The original factory-installed fixed TXVs for cooling and heating were both replaced with adjustable TXVs of the same size. Additionally, a variable frequency drive was installed to allow the compressor speed to be varied so that all refrigerants could be tested at the same capacity.
DR-55 and DR-5A were found to be near design-compatible alternatives to R410A in terms of capacity while providing improved efficiencies of ~4.5% at the A-rating conditions (26.7°C dry bulb/19.4°C wet bulb indoor and 35°C outdoor) and ~3% at the B-rating (27.8°C ambient) conditions.
Cyclic testing suggested DR-55 and DR-5A offer additional benefits over R410A during transient operation. Both showed less capacity loss (0% to +3%) and efficiency (+4% to +7%) compared with R410A at high ambient temperatures. Compressor discharge temperatures increased only modestly (-12.2 to -11.1ºC) up to 52°C ambient.
R32 required an 8.5% reduction in compressor speed to match R410A’s cooling capacity at the A-rating conditions. R32 produced an EER nearly 6% higher than R410A at the A conditions and ~4.5% better at the B conditions.
The single component refrigerant, currently being adopted by many Japanese air conditioning manufacturers, performed similar to DR-55 and DR-5A at high ambient temperatures with respect to capacity. However, R32’s efficiency appeared to drop off above 43°C ambient. As the test team expected, R32 exhibited a significantly increased compressor discharge temperature, starting 11°C above R410A at 18°C ambient, increasing to +15°C at 35°C ambient, and then increasing more rapidly to +24°C at 49°C ambient at which point the unit’s maximum discharge temperature limit of 121°C prevented operation.
The full report can be viewed and downloaded here.
DR-55 is 5% better as drop-in – September 16, 2015
USA: Chemours R410A replacement DR-55 is reported to have performed well in high ambient drop-in tests on a R410A rooftop air conditioner. Read more…
Is DR-55 best option to replace R410A? – September 2, 2015
USA: Chemours has unveiled further details of a new refrigerant blend to rival R32 in the search for a lower GWP alternative to R410A in air conditioning systems. Read more…
R32 passes high ambient test – September 16, 2015
SAUDI ARABIA: Tests in Saudi Arabia have indicated that, as well as having better performance, R32 might be compatible with existing R410A air conditioners in high ambients. Read more…