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The separate and combined use of NH3 and CO2 in refrigeration systems. 1. Ammonia and CO2/NH3 cascade systems.

Author(s) : VISSER K.

Summary

Ammonia refrigeration systems are widely used in many primary industrial food processing industries like livestock conversion plants, fish and coffee processing facilities, vegetable freezing plants, malting plants and breweries, ice cream plants, etc. Ammonia with its excellent thermodynamic and physical properties has enjoyed a continuous use now for almost one and a half centuries and popularity has not been materially affected by the advent of the CFC's in the early 1930's, soon to be followed by HCFC's. CO2 on the other hand, was a popular refrigerant for about 60 years from the 1870's onward, but its decline started with the arrival of CFC's. Svariegaard (1996) showed that the last CO2 plants were built for mainly marine applications around the late 1950's. In this paper, evidence is presented that two-stage ammonia refrigeration systems applied to industrial freezing and cold storage facilities are more energy efficient than CO2/NH3 cascade systems at evaporating temperatures of about -38°C and higher. Below about -38°C evaporating temperature CO2/NH3 cascade refrigeration systems for the same duty are more energy efficient. It is also shown, that in the case of two stage refrigeration plants with significant high stage and AC cooling loads being serviced from the same control plant, a CO2/NH3 cascade system with DX CO2 for chilling and AC cooling loads is about 5% more energy efficient than a two stage ammonia system using glycol as a secondary refrigerant. The use of ammonia heat pumps as a third stage added to a two stage ammonia plant or CO2 ammonia cascade system is discussed and calculated performance figures are presented. See also this Bulletin, reference 2009-1433.

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Pages: 2009-2

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Details

  • Original title: The separate and combined use of NH3 and CO2 in refrigeration systems. 1. Ammonia and CO2/NH3 cascade systems.
  • Record ID : 2009-1432
  • Languages: English
  • Source: 3th Conference on Ammonia Refrigeration Technology. Proceedings: Ohrid, North Macedonia, May 7-9, 2009.
  • Publication date: 2009/05/07

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