Spanish supermarket group DIA has chosen both ammonia/NH3 (717) and CO2 (R744) technologies for a new 68,000m2 (731,946ft2) distribution warehouse, which is being built at the Green Logistics Park in Illescas, south of Madrid.

The warehouse will use an ammonia-glycol chiller for medium-temperature cold rooms, and a CO2 cascade system condensed with glycol for low-temperature rooms. In a novel configuration, glycol chilled by the ammonia will be used to condense the CO2.

The warehouse, expected to open in 2022, will supply around 500 stores in Madrid, and the Castilla-La Mancha and Castilla y León regions.

The combined 3,000kW (853TR) refrigeration system will be supplied by Tewis Smart Systems, including 2,400kW (682TR) for medium-temperature storage and 600kW (171TR) low-temperature rooms.

The project, which is described as “one of the most ambitious industrial refrigeration projects in Spain” on Tewis’ website,will include open screw compressors and floating condensation for the two medium- temperature ammonia chillers. It will be a “low-charge, but flooded” system delivering 35% monopropylene glycol (MGP) at -8 to -4°C (17.6 to 24.8°F), according to Alfonso Olcina, Sales Manager at Tewis.

For the low temperature subcritical CO2 system, Tewis will be using semi-hermetic compressors, condensed with the glycol from the ammonia system at -2°C (28.4°F). “Each CO2 rack carries plate exchangers for at least 150% of its condensation demand,” said Pablo Pacheco, Industrial Sales Manager at Tewis..

The building’s air conditioning will be separate from the refrigeration system.

To increase energy efficiency, the warehouse employs heat recovery to defrost the medium temperature section with hot glycol. It also uses hot gas to defrost the low temperature system.

However, DIA is looking at more than the refrigeration system to make the warehouse environmentally friendly. The company is also installing solar panels to ensure that the facility will be energy self-sufficient.

“The Green Logistics Park in Illescas is one of the most ambitious industrial refrigeration projects in Spain”