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IIR document

N2O-CO2-mixtures as refrigerants for temperatures below -50 °C.

Number: pap. n. 1532

Author(s) : KAUFFELD M., MAURATH T.

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 and Ethane 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. But possible exothermal decomposition of N2O calls for additional measures to be able to operate such systems safely. A freeze dryer has been developed, built and successfully operated at evaporation temperatures down to -80 °C with mixtures of N2O and CO2 and different lubricants. The unit achieved similar energy efficiency as the standard HFC-equipment. Possible decomposition of N2O could successfully be supressed by various measures. CAUTION: Pure N2O as well as mixtures of N2O and CO2 with hydrocarbon based lubricants can result in serious decomposition reactions increasing the pressure inside a refrigeration system approximately eightfold.

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Pages: 8

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Details

  • Original title: N2O-CO2-mixtures as refrigerants for temperatures below -50 °C.
  • Record ID : 30026120
  • Languages: English
  • Source: Proceedings of the 25th IIR International Congress of Refrigeration: Montréal , Canada, August 24-30, 2019.
  • Publication date: 2019/08/24
  • DOI: http://dx.doi.org/10.18462/iir.icr.2019.1532

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