The new refrigerants, Daikin’s R32 and Honeywell’s development blend L41b, are both seen as potential replacements for R410A in air conditioning and heat pump systems. The calorimeter tests were carried out as part of the Air Conditioning, Heating and Refrigeration Institute (AHRI) Low-GWP Alternative Refrigerants Evaluation Programme (Low-GWP AREP) and follows similar tests carried out last year with DuPont’s low GWP R410A replacement DR5.
R32 is being used by Daikin in all its new residential and small commercial air conditioners and has also been adopted by many of Daikin’s Japanese competitors. A single component refrigerant, R32 has no refrigerant glide and a GWP of around 675.
Honeywell’s L41b blends R32 with 27% of the new HFO R1234ze(E). The addition of the HFO drops the GWP below 500. L41b has moderate refrigerant glide of about 8ºF (4.5ºC).
DR5 is DuPont’s development blend, again based on R32 but this time with the addition of 27.5% of the HFO R-1234yf. Again, the addition of the HFO drops the GWP below 500 and like the other two refrigerants is in the “mildly flammable” A2L classification. DR5 has relatively low refrigerant glide of about 2ºF (1.1ºC)
All three tests were carried out on a Copeland Scroll ZP31K5E-PFV compressor at Emerson’s A2L research calorimeter lab test facility located in Sidney, Ohio.
Each was carried out as a drop-in test. No optimisation, oil or hardware changes were made to account for any of the alternative refrigerants, as per AHRI Standard 540 requirements.
In the drop-in tests R32 was found to exhibit a 3-5% higher capacity than R410A, but with about 3-5% lower EER. The higher capacity is due to R32’s much higher specific heat overcoming its lower mass flow. The full calorimeter test results can be viewed here.
Compressor capacity with L41b versus R410A was within 75 to 85% of rated performance across the operating map of the tested compressor. At lower evaporating temperatures, capacity with L41b was found to be lower than R410A. This implies that L41b compressor performance in cooling is relatively better than its performance in heating. The tested compressor COP of L41b was between 85 and 100% of R410A within the operating envelope. The full calorimeter test results of L41b can be viewed here.
The calorimeter testing of DuPont’s DR5 showed comparable performance to R410A, its capacity being within 90 to 100% of rated performance across the operating map of the tested compressor. Like L41b, the reduced capacity at lower evaporating temperatures suggested that the cooling performance of DR5 is relatively better than its heating performance. The tested compressor COP of DR5 was between 95-110% of R410A efficiency within the operating envelope, with efficiency greater at higher condensing temperatures. The full calorimeter test results of DR5 can be viewed here.
All of the refrigerants could be expected to show improved capabilities if used in compressors and systems specifically optimised for the new gases.