Spanish hypermarket cuts CO₂ emissions 65%

In recent years, protection of the environment and energy efficiency have become major concerns for society as a whole. Being part of the global Auchan Group, which insists on making a sustainable development a daily reality, the Alcampa Management looked for a green refrigeration solution for the new hypermarket in Toledo. 

From the outset, Danfoss took part in designing the solution, thanks to the experience it has gained in the over 1500 sub-critical and trans-critical installations throughout the world. 

To ensure optimum performance and the lowest carbon footprint, contractor Maxfri Costa S.L, chose a cascade R134a/CO₂ system together with Danfoss. Choosing this system, Alcampo's annual CO₂  emission from the refrigeration system will be reduced by up to 65%. 

Combined with a lesser load of refrigerant needed, the hypermarket will gain substantial savings by shifting to the less expensive CO₂  compared to HFC refrigerants. 

The maintenance of a Danfoss CO₂ refrigerating system is the same as for an HFC system.

A sustainable CO₂ refrigeration system with heat recovery is an excellent solution for retailers as it generates cold and heat at the same time.

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 than other HFC refrigerants.

Normally, the heat generated by a refrigeration system is released straight out into the fresh air. This is avoided, when the refrigeration system uses CO₂ as a refrigerant.

Although the CO₂-refrigerant is very attractive, it appears to be difficult to handle at first glance. The major difficulties stem from the need to use higher working pressures than usual, and the fact that algorithms for the electronic controllers must be adapted to the specific properties of this refrigerant. With a complete range of both electronic controllers and line components that make it possible to overcome these difficulties, together with ample experience and knowledge in the field, Danfoss could guide Maxfri Costa in selecting the components and optimizing the system parameters. 

The R134a circuit cools the refrigerated services (refrigerator cabinets and cold storage rooms), expanding directly via AKV electronic valves. Besides performing the refrigeration cooling, the R134a circuit is also used to remove heat from the CO₂ circuit by condensation of CO₂ in a plate heat exchanger in which the R 134a expansion is carried out directly via ETS electronic valves.

In the same manner, the CO₂ cools the freezer services (freezer units and walk-in freezers), expanding directly via AKV electronic valves. The CO₂ is then compressed in a CO₂ compressor and condensed in the R134/CO₂ heat exchanger.

Refrigerant R134a was chosen instead of R404A due to its excellent thermodynamic properties and its low Global Warming Potential (GWP). As regards the CO₂, it meets the technical specifications perfectly. It is a natural refrigerant that has little impact on the deterioration of the Ozone layer and has a Global Warming Potential (GWP) index of 1.

In terms of GWP, if we compare the traditional R404A installation with the new R134a/CO₂ installation, assuming the level of leaks remains the same each year, the environmental impact measured in the equivalent of kg of CO₂ will be reduced by up to 65%. 

From an energy saving point of view, another of the participants in the project (Fergasa), using a simulation tool that looks at all possible action areas relating to the Danfoss ADAP-KOOL® electronic controller, estimated the additional energy saving of the installation, comparing two versions of the same installation:

• The traditional version featuring two R404A central units with AKV electronic expansion valves on all services, etc.
• The new suggested R134a/CO₂ version, also with AKV electronic expansion valves on all services, etc.

Alcampo is a hypermarket chain in the French Auchan Group. In 2014, the group operated in 16 countries, employed 302 500 people and generated in 2013 €62.1 in revenue including taxes for the chains. The group operates within banking, real estate, e-commerce, and hyper-/supermarkets among other businesses.

> 2,500 to 22,000 m² of sales area
> 150 to 900 employees
> 5,000 to 30,000 customers a day
> 30,000 to 100,000 food and non-food products
> 20 to 90 checkouts
> 1 petrol station
> 1,000 to 5,000 parking spaces