USA: R1234ze and a new Daikin blend of R134a and 1234yf have shown good results in drop-in tests in an  R134a air-cooled screw chiller.

The Daikin blend – D4Y – virtually matched the capacity of pure R134a but its COP was 3.6% inferior to the established refrigerant. Although no GWP is recorded for DY4, its stated composition of 40% R134a to 60% 1234yf suggests a GWP of around 520.

R1234ze, a refrigerant already on active field trials in chillers in the UK, showed a reduced capacity (77.4%) compared to R134a but returned a 5.5% improvement in COP.

The tests were carried out at the Daikin McQuay facilities in Minneapolis as part of the US Air Conditioning, Heating and Refrigeration Institute’s (AHRI) low-GWP alternative refrigerant evaluation programme.

Before the drop-in trials, baseline tests were first carried out with R134a on the 200 ton chiller with a single refrigerant circuit, variable speed screw compressor and economizer refrigerant cycle. All the tests were conducted using the same equipment and test facility without any modifications to the equipment, test facility or instrumentation.

No special problems or issues were observed during the testing. Both candidates were considered to have merits to be considered for further evaluation and it’s thought that system optimization could achieve a suitable compromise between efficiency, capacity, and cost.

The full report can be found here.

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