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Document IIF

Mélanges de CO2 et de N2O utilisés en tant que fluides actifs dans les cycles en cascade.

Blends of CO2 and N2O as working fluids in cascade cycles.

Auteurs : DI NICOLA G., GIULIANI G., POLONARA F., et al.

Résumé

The performance of a cascade refrigeration cycle operated with blends comprising carbon dioxide (CO2 or R744), nitrous oxide (N2O or R744A), with ethane (C2H6 or R170) as the low-temperature working fluid, was analyzed over a wide range of compositions and intermediate temperatures. To conduct the analysis, a property software based on the Carnahan-Starling-De Santis (CSD) equation of state was developed, using binary interaction parameters derived from our experimental data for CO2 + N2O and N2O + C2H6 systems, and from VLE data for the amply-studied CO2 + C2H6 system. The properties of the investigated blends were used to simulate the behaviour of a cascade cycle using ammonia (R717) as the high-temperature-circuit working fluid at the condensing temperature of 30 °C and operating at a low-temperature-circuit evaporating temperature of -70 °C. In the simulation, the value of improving the COP by using a suction-liquid heat exchanger on the low-temperature side of the circuit was also studied, as were the sensitivity of the COP to subcooling on the low-temperature condenser, and the temperature differences between the high-temperature evaporator and the low-temperature condenser. The results show that the N2O blends are an attractive option for the low-temperature circuit of cascade systems operating at temperatures approaching 200 K.

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Format PDF

Pages : 2005-3

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Détails

  • Titre original : Blends of CO2 and N2O as working fluids in cascade cycles.
  • Identifiant de la fiche : 2006-0558
  • Langues : Anglais
  • Source : Commercial Refrigeration. Thermophysical Properties and Transfer Processes of Refrigerants. Proceedings of the IIR International Conferences.
  • Date d'édition : 30/08/2005

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