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R744 Ejector supported parallel vapour compression system


The average energy use of European supermarkets is in the range of 300 to 600 kWh/m2 (Energy star, 2008;
Arias, 2005). Around 50% of the energy is used to the refrigeration equipment which provides cooling and
freezing capacity for the display cabinets and the cold / freezing storage rooms. Most of the current
refrigeration systems are applying HFC 404A as the working fluid. In Accordance to the survey in the latest
IPCC/TEAP Special Report (2007), the average annual leakage rates of existing European HFC supermarket
units are between 15 and 20 % of the total refrigerant charge. On a global perspective the commercial
refrigeration leakage rates are around 30 %, while HCFC 22 is the most common refrigerant. Therefore,
effort should be given to identify alternative refrigerants which are able to improve the energy efficiency
compared to current HFC solutions. Preference should be given to natural working fluids, since their long
term environmental impact can be foreseen and they minimize the direct GWP contribution.
Currently there are more than 2000 commercial refrigeration system, applying carbon dioxide (R744), manly
located in Central- and Northern Europe. The efficiency challenge related to ordinary R744 booster systems
operated at high ambient temperatures (Finckh, 2011) can be overcome by an improved system design as
described in this paper. As one possible example, an enhanced R744 commercial refrigeration system with
parallel compressor technology and ejector support is described, as implemented in a large supermarket in
the region of Fribourg (Switzerland) during summer 2013. First measurement results are analysed and
evaluated. Copyright © 2014 IIR/IIF. All rights reserved


Academic chapter/article/Conference paper





  • Switzerland
  • Unknown
  • SINTEF Energy Research




International Institute of Refrigeration


3rd IIR International Conference on Sustainability and the Cold Chain 23rd 24th and 25th June 2014, St Mary’s University, Twickenham, London, UK





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