Bitzer and Eletrofio Refrigeracao Comercial developed CO2 refrigeration technology used in a hypermarket in Spain over a period of two years. The CO2 system reduces the energy consumption of the freezers by 20 percent, which translates into a 5 percent reduction in energy consumption for the entire refrigeration system, those involved in the project said.
The CO2 refrigeration system is called Eco2Lógico. It is a cascade system that uses CO2 as the refrigerant in the low-pressure (subcritical) stage, with direct expansion, and cools the freezers. Propylene glycol is used as the heat transfer fluid in a pumped system circulating in the CO2 cascade condensers. In the high-pressure stage, a low HFC-134a charge is used.
The freezer system is divided into three compact racks with two compressors installed in parallel. The CO2 racks were installed on the ceiling of the underground car park, underneath the shop floor, positioned near the freezer islands.
The high-pressure system consists of six semi-hermetic Bitzer compressors installed in a rack house.
A German discount store has decided to install Mistral CCU single-temperature range units with an integrated gas cooler/condenser. Mistral CCU units can be configured as a chiller, freezer, or air conditioner and be upgraded with heat exchanger on the warm side.
Mistral CCU is designed for convenience stores, supermarkets, gasoline stations, restaurants, hospitals, hotels, and industrial use. Compact and weather-protected, this outdoor unit saves indoor space and results in easier installation since it requires less piping, the manufacturer said.
The Southern Co-operative, which has 120 shops in England, is installing its first chiller cabinets using CO2 as a coolant. The UK now has more than 260 CO2 transcritical refrigeration installations across the country.
The first CO2 installation was in Swansea in 2006. According to reports, retailers have led investment in CO2 technology. The list of companies having chosen the refrigerant includes Asda, Harrod’s, M&S, Sainsbury’s, and Tesco.
The Southern Co-operative is the latest supermarket chain to do so. Steve Tremlett, head of business development for Southern Co-operative, said, “All of the lighting will be LED, the refrigeration systems will actually use CO2 as a climate-friendly coolant, and the fridges themselves will have doors to help minimize power consumption. Power will also be saved through high-spec insulation, and electricity is monitored using sophisticated smart meters to ensure that store equipment is running efficiently.”
Publication date: 04/23/2012