IIR document

New copper-based heat exchangers for R744 refrigerant. 1 : New technologies for tubes and coils.

Number: pap. n. 4

Author(s) : SHABTAY Y., BLACK J. R. H., COTTON N. D.

Summary

The replacement of current refrigerants with zero ozone depletion potential (ODP) and virtually zero global warming potential (GWP) refrigerants has important implications for heat exchangers, heat pumps, air conditioners and refrigeration system design, and the materials choices in these designs. The use of CO2 as a refrigerant requires components to withstand higher pressures compared to conventional refrigerants. Part I presents critical information about smaller-diameter copper tubes and other heat-exchanger technologies, and Part II discusses design principles and presents example case studies for CO2. Seamless copper tubes with or without inner-grooves can be fabricated from a high-strength copper-iron alloy, reducing wall thickness and thus cost. Coil processing can usually be performed with existing manufacturing equipment since the high strength alloys are brazeable and weldable. Corresponding fittings made from the high strength alloys are also available. Since the volume of CO2 required to achieve the same cooling effect is much lower than for HFCs, components and tubing can be smaller than in conventional installations. In practice, accommodating the high pressures of CO2 systems is advantageous because the smaller diameter tubes used to withstand higher pressures also reduce system size and materials requirements. CuFe2P alloy tubes at small diameters are further advantageous for use in high-pressure CO2 cascade, transcritical and secondary-loop refrigeration systems due to their high strength without increasing wall thickness in the transmission lines.

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Pages: 8 p.

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Details

  • Original title: New copper-based heat exchangers for R744 refrigerant. 1 : New technologies for tubes and coils.
  • Record ID : 30014580
  • Languages: English
  • Subject: Technology
  • Source: 6th Conference on Ammonia and CO2 Refrigeration Technology. Proceedings: Ohrid, North Macedonia, April 16-18, 2015.
  • Publication date: 2015/04/16

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