Supermarkets: retrofit of refrigerating systems from R404A to R449A

The existing R404A refrigeration system of a Waitrose supermarket located in Holsworthy (UK) has been retrofitted with R449A refrigerant (HFO/HFC blend of R32, R125, R134a and R1234yf). R449A has a rather high GWP (1397) but significantly lower than R404A’s GWP (3922) and complies with EU F-gas Regulation requirements. The refrigeration system consists of two high temperature packs and one low temperature pack connected to 27 display cabinets and 4 cold rooms. No components or oil changes were required, making the retrofit very fast and straightforward.

During the monitoring period – two weeks before the retrofit and then three weeks after the retrofit – the high temperature systems energy consumption was reduced by 8.7%. For the low temperature system, the energy consumption was reduced by 3%. For the total refrigeration system, this equates to a reduction in energy consumption of 6.6%.

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Furthermore, a paper recently published in the International Journal of Refrigeration presents the measurements of a light retrofit replacement of R404A using R449A in a medium temperature indirect refrigeration system (secondary fluid temperature at the evaporator outlet between -9 and -4?°C). It shows that with a slight expansion device adjustment and 4% increase of refrigerant charge, R449A can be used in this refrigeration system designed for R404A because of its suitable thermodynamic properties and acceptable maximum discharge temperature. At a secondary fluid temperature at condenser inlet of 30?°C, the COP of R449A nearly matches that of R404A (both were between 1.9 and 2.2), despite having approximately 13% lower cooling capacity.

 

Pavel Makhnatch et al. “Retrofit of lower GWP alternative R449A into an existing R404A indirect supermarket refrigeration system”. International Journal of Refrigeration Vol. 76 (2017): 186-192 http://bit.ly/Fridoc-IJR-76-186