A CO2 transcritical system designed, built and maintained by local firm Commercial Refrigeration Services (CRS) serves the entire heating and cooling needs of a Woolworths supermarket in the Johannesburg district of Midrand, South Africa.

The two racks serve the medium-temperature and low-temperature cabinets respectively. The system harnesses adiabatic cooling and parallel compression. Heat reclaimed from the racks covers the entire store’s heating needs.

“The system’s capacity is 400 kW,” said Wynand Groenewald, head of engineering at CRS. “Thanks to the adiabatic cooling, it doesn’t need to go into transcritical mode very often,” he said.

“The average annual temperature in Jo’burg is 16 degrees Celsius, so we’ve found that for around 90% of the year we’re running subcritically,” Groenewald explained.

“Going into the future, the majority of Woolworths’ new builds and revamps will be CO2 transcritical.

Wynand Groenewald, CRS

The Woolworths Midrand system was commissioned in January 2017.

“Currently Woolworths have close to 70 stores running on CO2 transcritical,” said Groenewald. “Going into the future, the majority of their new builds and revamps will be CO2 transcritical,” he added.

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