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Commercial refrigeration using CO2 as refrigerant: system design and experimental results.

Author(s) : NEKSÅ P., GIROTTO S., SCHIEFLOE P. A.

Summary

Two supermarket refrigeration concepts based on self-contained display cabinets with CO2 refrigeration units have been investigated. In the first concept the refrigeration units placed in each cabinet reject heat to a waste heat recovery loop. Utilising the trans-critical CO2 process, it is possible to have a very large temperature glide in the loop, typically 50-60 K, and a correspondingly low volume flow rate. Waste heat with high temperature (70-75 deg C) is available for tap water- and/or space heating. Excess heat is rejected to ambient air by direct heat exchange and, if necessary, by using an auxiliary chiller. Simulations of the system for a medium size supermarket have been carried out. In the second concept, the CO2 units were equipped with a condenser in order to reject the heat directly to the shopping area when space heating is required. In the warm season with a heat surplus, the waste heat recovery loop was used to remove the heat. For the two concepts, results are compared with those of the base line R22 system. Two test cabinets have been made for performance and operational testing purposes. Still the efficiency is about 10-15% lower than targeted, but there is room for improvements in all components. The largest potential is within the compressor, which is now a first version semi-hermetic CO2 compressor.

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Pages: p 270-280

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Details

  • Original title: Commercial refrigeration using CO2 as refrigerant: system design and experimental results.
  • Record ID : 1999-2823
  • Languages: English
  • Source: Natural Refrigerants, Energy Efficiency, Cost and Safety. Natural Working Fluids '98. IIR-Gustav Lorentzen Conference.
  • Publication date: 1998/06/02

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