German wholesale giant Metro AG has started converting its Russian R404A stores to CO2 (R744) refrigeration, having completed the first conversion to transcritical CO2 at a Cash & Carry hypermarket in Orenburg, southwest Russia.
In its upcoming fiscal year, Metro’s next two conversions from R404A to transcritical CO2 will take place at stores in Stavropol and Astrakhan, Russia, said Olaf Schulze, Metro AG’s Director for Energy, Facility and Resource Management.
The R744 conversions in Russia – and elsewhere – are part of Metro’s F-Gas Exit Program, initiated in 2013. The program aims to reduce the company’s f-gas emissions by 90% by 2030. The progress has been good so far. In May 2019, 27% of Metro’s stores were using natural refrigerants; and as of December 2020, 114 used transcritical CO2.
In total, Metro runs 97 stores in Russia, and one storage facility that uses ammonia. The company has 32 Russian stores that use CO2, 23 of which have subcritical systems (installed since 2015) and nine with transcritical systems, the first installed in 2018. Going forward, the company will only install transcritical systems, Schulze said.
A year ago, Metro finished phasing out R22 in its Russian operations and turned its sights towards R404. “The R22 is dead, now we will kill softly the R404A,” said Schulze at the time.
Parallel compression and ejectors
The Orenburg conversion, completed last November, was carried out in collaboration with Russian contractor Ingenium LLC. The 10,000m2 (107,640ft2) hypermarket has been equipped with two CO2 transcritical racks providing both low-, medium-, and high-temperature cooling, with evaporation temperatures of -32°C, -7°C and 0°C respectively (-25.6°F, 19.4°F and 32°F).
Each rack has parallel compression and liquid-and-gas ejector technology as well as a pumped glycol solution for cooling of the high-temperature storage areas. It includes semi-hermetic reciprocating compressors from Bitzer and plate heat exchangers between the R744 and the glycol loop. To ensure efficiency at part loads, two of the compressors on each rack are equipped with frequency converters.
The system is automated with Danfoss’ Adap-Kool controllers, and the shop is furnished with cabinets from Freor, all with doors to save energy. Storage room air coolers were provided by Guentner and LU-VE.
The pumps for the glycol system in the high-temperature areas are equipped with frequency drives. This “reduces energy consumption while reducing the required flow rate of the coolant during system operation,” Ingenium Technical Director Anton Rostokin said.
The refrigeration system’s gas coolers, manufactured by LU-VE, have fans with EC motors with a 10%-15% higher efficiency than standard asynchronous motors, according to Rostokin. This “allows for smooth regulation of the refrigerant condensation pressure in winter, or the temperature of the cooled CO2 gas in hot weather,” he explained.
The system includes an option for heat reclaim, via the hydraulic circuit of the system, to produce hot water and store heating.
20 R744 projects
Ingenium was founded in 2007 and is based in Moscow. The company designs, installs and services refrigeration systems with natural refrigerants for the the agro-industrial sector, food processing plants, retail and food wholesale.
The company has carried out approximately 20 large R744 projects and describes itself as the largest purveyor of integrated solutions in retail and logistics in Russia. For the Orenburg project, Ingenium also supplied heat curtains for the store.
Talking about his company’s dedication to R744, in a market where such installations are still relatively rare, Rostokin said “using [R744] allows you to achieve high energy efficiency indicators, saving up to 25% of energy costs compared to HFC refrigerants.”
Using [R744] allows you to achieve high energy efficiency indicators, saving up to 25% of energy costs compared to HFC refrigerantsAnton Rostokin, Ingenium.