South African consultant Future Green Now (FGN) has designed an integrated CO2 (R744) system to serve the medium-temperature load, freezers and air-conditioning of Massmart’s Makro warehouse store in Woodmead (Johannesburg), resulting in estimated energy savings of 17%.

Two transcritical CO2 booster racks designed by FGN were installed by South African contractor and manufacturer Matador Refrigeration.

“Yet another success story getting rid of harmful #HFC based #refrigeration system by introducing #sustainable #natural solutions making use of #CO2 as a refrigerant,” said Wynand Groenewald, Founder of FGN in a recent LinkedIn post.

Upgrading for the future

Choosing CO2 for the Woodmead retrofit was motivated by Massmart’s ongoing global initiative to go natural, including in all South African Makro stores. Makro operates 22 massive warehouse stores situated in the large metropolitan centers of South Africa, selling food, liquor and general merchandise to retail and wholesale customers.

Woodmead’s existing refrigeration system, charged with R404A, was reaching the end of its life after nearly 30 years in operation. The store owner also wanted to increase the size of the facility and needed a refrigeration system that could cope with the additional load.

To that end, the FGN team designed a booster system complete with parallel compression and adiabatic cooling. The system incorporates BOCK compressors, Danfoss controls and parts from local South African suppliers such as Colcoil evaporators, Viola receivers and ESK oil management.

The system is split into two racks, both with low-temperature (LT) and medium-temperature (MT) suction groups, as well as air-conditioning. The LT side offers 160kW (45.5TR) capacity at -30°C (-22°F), while the MT offers 600kW (170.6TR) at -8°C (46°F).

During this upgrade, the existing air-conditioning system was connected to the main refrigeration installation and the evaporator changed to a CO2 coil to allow it to run on a natural refrigerant as well.

FGN calculated that if the store remains at the same capacity and the same electrical load is assumed, estimated savings of around 17% could be expected at full load.

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