21ST INTERNATIONAL CONGRESS OF REFRIGERATIONUSA: Honeywell has been testing a new low GWP refrigerant as a potential replacement for R404A in hermetically-sealed refrigeration systems.

The refrigerant manufacturer used last month’s compressor conference at Purdue University to reveal some of the results of tests it had been carrying out with a new “mildly flammable” refrigerant blend in a single door reach-in freezer.

While Honeywell has not divulged the components of the blend, code-named HDR-110, from the information supplied it has a GWP under 150, a glide of around 6ºC and a slightly lower pressure than R404A.

Tests were carried out on a 3/4hp R404A freezer with an internal volume of about 700 litres and rated capacity of around 560W. The top-mount self-contained refrigeration unit had a nominal charge of 354g of R404A and comprised a 1/2 hp hermetic compressor, air-to-refrigerant tube-in-fin condenser and evaporator, suction-line liquid-line heat exchanger and thermostatic expansion valve.

21ST INTERNATIONAL CONGRESS OF REFRIGERATIONInitial drop-in tests performed to ASHRAE standard 72-2005 showed HDR-110 had capacities below 90% of baseline tests with R404A and a slightly lower efficiency. However, when the original parallel-flow evaporator was altered to a counter-flow arrangement and the expansion valve adjusted to allow for HDR-110’s slightly lower pressure, the unit showed a 6% lower energy consumption and a near match in capacity.

HDR-110 will be included in phase II of AHRI’s Alternative Refrigerant Evaluation Programme but Honeywell notes that more work is needed to fully explore potential application of this refrigerant. It also recognises that although some changes to the equipment would be required due to the refrigerant’s “mild flammability”, upcoming standard updates could potentially enable such refrigerants to be used in small self-contained refrigeration systems with more relaxed requirements than hydrocarbons.

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