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Performance testing and comparison of liquid overfeed and cascade CO2 systems with R-404A primary.

Author(s) : REES B., ROHRER C., SHAPIRO D., et al.

Summary

A subcritical CO2 parallel compressor system was setup and tested, and energy efficiency comparisons were completed. R-404A was the high-side refrigerant, and heat was rejected at controlled condensing temperatures. CO2 was the low side secondary refrigerant and heat was added from a glycol-heated evaporator. For low evaporating temperatures, tests were conducted with: 1) pumped liquid CO2 in a liquid overfeed system; and 2) direct expansion of CO2. The direct expansion approach used a cascade refrigeration system with CO2 low side compressors and R4-04A high side compressors. For medium evaporating temperatures, tests were conducted only with pumped liquid overfeed, and no CO2 compressors were used. Semi-hermetic piston compressors were used for both R-404A high side and cascade CO2 low side. Performance comparisons were made between these two types of CO2 systems and baseline direct expansion R-404A. At high temperature ratio conditions, the cascade CO2 system was roughly 5% more efficient than either the baseline R-404A direct expansion system or pumped liquid CO2 system. At low temperature ratio conditions, the energy efficiency of the pumped liquid system was roughly equal to the R-404A baseline.

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Pages: ICR07-B2-123

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Details

  • Original title: Performance testing and comparison of liquid overfeed and cascade CO2 systems with R-404A primary.
  • Record ID : 2008-0110
  • Languages: English
  • Source: ICR 2007. Refrigeration Creates the Future. Proceedings of the 22nd IIR International Congress of Refrigeration.
  • Publication date: 2007/08/21

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