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N2O/CO2-Mixtures as Refrigerants for Temperatures below -50 °C.

Author(s) : KAUFFELD M., MAURATH T., GERMANUS J., ASKAR E.

Type of article: IJR article

Summary

The EU F-Gas Regulation grants exceptions from the GWP-related placing on the market prohibition for stationary refrigeration equipment for applications below -50 °C. Nonetheless, non-flammable refrigerants, which can be used for that temperature range, become increasingly expensive and rare inside the EU due to the phase down of HFCs under the regulation. Flammable alternatives based on methane, ethane and ethylene are available, but are not viable for all applications due to their flammability. Carbon dioxide cannot be used for applications below -50 °C due to CO2's triple point at -56 °C. Nitrous oxide with a triple point at -92 °C seems to be an alternative. However, possible exothermal decomposition of N2O calls for additional measures in order to be able to operate such systems safely. Two low-temperature systems have been developed, built and successfully operated at evaporation temperatures down to -80 °C with mixtures of N2O and CO2 and different lubricants at ILK and Karlsruhe University of Applied Sciences. The units achieved similar energy efficiency as the standard HFC-equipment used for freeze drying. Possible decomposition of N2O could successfully be supressed by various measures.

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Pages: 316-327

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Details

  • Original title: N2O/CO2-Mixtures as Refrigerants for Temperatures below -50 °C.
  • Record ID : 30027532
  • Languages: English
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 117
  • Publication date: 2020/09
  • DOI: http://dx.doi.org/10.1016/j.ijrefrig.2020.04.026
  • Document available for consultation in the library of the IIR headquarters only.

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