Harrods chooses CO2 transcritical refrigeration to 'future proof' business

By R744.com team, Dec 13, 2011, 09:40 3 minute reading

Harrods, the world famous London department store, has installed a CO2 transcritical refrigeration system in its Food Hall. The existing R22 and R404A refrigeration systems cooling the cold rooms and food cases have been replaced with a purpose built CO2 plant room using innovative parallel compression technology. Harrods took the pioneering decision to leap-frog HFCs and opt for a natural solution.

Known for its splendour and luxury, Harrods department store occupies a 20,000m2 site in a Grade II listed building, parts of it dating back to the 1800s. Its seasonal Christmas department and the Food Hall, stocking an impressive selection of international goods in beautiful displays, attract visitors from around the world. To replace its aging refrigeration system Harrods installed environmentally-friendly CO2 technology. 
 
One of the significant factors in the selection of CO2 was the fact that commonly used HFC refrigerants would in the future come under increasing pressure due to their high global warming potential (GWP).
 
CO2 installation
 
Purpose-built, the plant room houses three HT/LT transcritical R744 packs, each delivering 160kW cooling. The new CO2 system also provides refrigeration for more than all the cold rooms, allowing the technical team to introduce CO2 to areas of the business that had been integral units. This has improved efficiency.
 
Technical Innovation
 
The installed CO2 system installed uses an innovative parallel compression system. In a normal CO2 transcritical system the flash gas is passed through a pressure reducing valve and fed to the main compressor suction port at a pressure or 27 bars. In the parallel compression system it is fed into a separate compressor operating a suction pressure of 37 bars. This means at approximately 40% to 45% of the total refrigerant flow is compressed through a pressure ration of 2.43:1 instead of 3.33:1 with a significant overall reduction in compressor power input.
 
Harrods Food Hall retrofit project aims
  • To replace the existing HCFC‐based plant with a new environmentally responsible system based on CO2 – avoiding reliance on environmentally harmful HFCs
  • To adopt a technology that would future proof the business against new levies that may come into force with any refrigerant that has a high ODP or GWP
  • To optimise energy performance through heat recovery and minimise carbon emissions and thereby reduce the overall carbon footprint
  • To replace existing food display cases with modern, state‐of‐the‐art systems of control, LED Lighting, automated blinds and lighting control.

Award nominated energy efficient system 
 
Waste heat generated by the packs is harnessed for use in generating hot water for the store, with a heat exchanger coupled to the cold water supply to pre-heat water prior to passing to the gas boilers.
 
Mechanical plant room cooling is provided by direct expansion evaporators connected to each compressor pack. This ensures a maximum amount of unwanted heat is recovered to the domestic hot water system.
 
The Harrods Food Hall CO2 project has been nominated in the Client Energy Management Award category, the Collaborative Working Award category, and the Client of the Year category of the 2012 CIBSE Building Performance Awards.
 
Two phase project
 
Phase 1: CO2 plant installation, installation of five new Food Hall cases onto the new plant, and the conversion of coolers serving the food preparation area onto the existing R404a pack.
 
Phase 2: Involved installation and connection of the remaining food hall displays onto the new CO2 packs and commenced onto shop floor areas on the 2nd floor. [Historically integral units].
 
Participating companies
 
The design, manufacture and installation of the CO2 system involved: Styles and Wood, Riley Consulting, bja, WR Refrigeration, Huurre Group,  Iglu Cold Systems srl, Arneg, and enEx.

MORE INFORMATION

By R744.com team (@r744)

Dec 13, 2011, 09:40




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