Over the last few years, environmental protection has become a major concern for businesses and organizations worldwide, including Carrefour Market.
For Carrefour's new store at Jacques Cœur, contractor Teissonnière chose to work together with Danfoss on designing a refrigeration system with the lowest environmental impact as possible. The result became Danfoss' first cascade R134a/CO2 system, which was installed in 2013.
"Since CO2 isn't commonly used yet, many contractors find it difficult to choose the right equipment. We chose to work with Danfoss, as the Danish group offers complete CO2 solutions and has solid experience in designing CO2 systems," says Bernard Abrax.
Accurate temperature and operation control of display cases and cold rooms are vital for high-quality and safe food products. The R134a with a direct expansion valve cools the cold storage rooms and the refrigerator cabinets, whereas the CO2 cools the walk-in freezer and freezer units. R134a was chosen over R404A because of its excellent thermodynamic properties and its lower Global Warming Potential (GWP).
"The project has been a very positive experience. Once the learning phase is over, installing an energy-saving CO2 refrigerating system is similar to installing standard systems. CO2 is thus likely to become more widespread and accessible," says Bernard Abrax.
The maintenance of a Danfoss CO2 refrigerating system is the same as for an HFC system.
CO2 is a natural refrigerant with a low impact on ozone layer degradation and a GWP index of 1. CO2 has an excellent volumetric efficiency, which entails smaller diameters in the piping (a sizeable advantage as the price of copper soars) and a lesser load of refrigerant. CO2 offers a high energy output and is still less expensive on purchase than other HFC refrigerants.
Normally, the heat generated by a refrigeration system is released straight out into the fresh air, but this can be avoided if the refrigeration system uses CO2 as a refrigerant.
CO2 is both and attractive and complex refrigerant to handle. The difficulty for its use is the high working pressure it requires. Therefore, the Danfoss ADAP-KOOL®series were chosen for Carrefour.
ADAP-KOOL® case controllers offer highly efficient adaptive routines for each cabinet and cold room installation guaranteeing significant energy savings and early warning alarms to avoid potential food loss.
The store's two central refrigerating units are equipped with pack controllers AK-PC controls (AK-PC 840 for the refrigerating and AK-PC 740 for the freezing) that enable a floating HP and pilot the AKD frequency converters in order to adjust output to the refrigerating needs and thus limit the central electricity consumption. The AK-PC also commands the condensers' motor fans. Therefore, they therefore contribute to reducing the refrigerating system's sound power level. This is critical since the machine room is only a dozen meters away from the neighboring residences.
- Total, integrated store cooling to achieve maximum performance and minimum energy consumption
- Plug and play solution with all functions in one place, easy to set up and commission
- Award winning and innovative components with high reliability and low service and maintenance costs
- Great savings in terms of energy and costs for man power
- In-depth application knowledge and consulting services from a Danfoss expert near you
For the refrigerating and freezing units' regulation, AKV electronic expansion valves were installed on both systems. They are piloted by AK-CC 550 regulators for the R134a refrigerating and by AK-CC 550A CO2-specific regulators for the CO2 freezing. This electronic expansion valve regulation enables optimum filling of the evaporators since the auto-adapting superheat is kept under control. Therefore, seasonal temperature changes (summer/winter) don't have an impact on the refrigerating units' regulation.
The Carrefour Group is the leading retailer in Europe and the second-largest retailer in the world, employing nearly 365,000 people. With more than 10,100 stores in 34 countries, it generated revenues of €100.2 billion under banners in 2013. As a multi-local retailer, Carrefour is a partner for daily life. Every day, it welcomes more than 10 million customers around the world, offering them a wide range of products and services at fair prices.