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An experimental study on the use of variable capacity two-stage compressors in transcritical carbon dioxide light commercial refrigerating systems.

Author(s) : CARVALHO B.Y. K. de, MELO C., HORN-PEREIRA R.

Type of article: Article, IJR article

Summary

This paper focuses on experimentally investigating different cycle architectures with two-stage variable capacity compressors for light commercial refrigeration CO 2 systems. A system with two-stage rotary compressor and intercooler was used as a baseline. Tests with an iHX showed the existence of a minimum stable/safe superheating. Proper superheating control ( > 3 K) with an iHX increases the COP by 12.9%, 16.0%, and 17.2% in the compressor frequencies of 45, 60 and 75 Hz, respectively. To prevent instability a capillary tube selected for the lowest frequency can be used, but it reduces performance by up to 15.5% at higher frequencies. A cycle with iHX, two-stage expansion and intermediate flash-gas bypass was also studied. This cycle provided an average increase in cooling capacity of 7.5%, and gains in COP of 15.5%, 18.4% and 18.1%, at 45, 60 and 75 Hz, respectively. Flash-gas bypass control showed little benefit to performance, but improved cooling capacity by up to 12.1% when compared to the cycle with an iHX.

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Pages: 604-615

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Details

  • Original title: An experimental study on the use of variable capacity two-stage compressors in transcritical carbon dioxide light commercial refrigerating systems.
  • Record ID : 30027026
  • Languages: English
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 106
  • Publication date: 2019/10
  • DOI: http://dx.doi.org/10.1016/j.ijrefrig.2019.03.026

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