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Condensation heat transfer of R1234ze(E) and its A1 mixtures in small diameter channels.

Author(s) : AZZOLIN M., BERTO A., BORTOLIN S., DEL COL D.

Type of article: IJR article

Summary

R1234ze(E) has emerged in the recent years as low Global Warming Potential substitute for R134a in refrigeration and air-conditioning systems. As a drawback, R1234ze(E) is classified as a mildly flammable fluid (A2L class) and, in the search for non-flammable alternatives to R134a, hydrofluorocarbon/hydrofluoroolefin binary mixtures can be considered. In the present work, condensation tests are performed with R1234ze(E) and non-flammable binary mixtures R450A (R1234ze(E)/R134a at 58.0/42.0% by mass) and R515B (R1234ze(E)/R227ea at 91.1/8.9% by mass) inside two channels with inner diameter equal to 3.38 mm and 0.96 mm. R515B is an azeotropic mixture whereas R450A is a near-azeotropic blend (temperature glide 0.6 K at 40 °C). Heat transfer coefficients are measured at 40 °C saturation temperature and mass flux from 40 kg m−2 s−1 to 600 kg m−2 s−1. Flow pattern visualizations are recorded by a high-speed camera in the 3.38 mm inner diameter tube. Two-phase pressure gradients are measured in the 0.96 mm test section at mass flux equal to 200 and 400 kg m−2 s−1. The prediction accuracy of condensation heat transfer and two-phase pressure drop models is assessed against the experimental results. A comparative study between the tested fluids and R134a, accounting for both the heat transfer coefficients and the two-phase pressure drops, is performed.

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Pages: 153-165

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Details

  • Original title: Condensation heat transfer of R1234ze(E) and its A1 mixtures in small diameter channels.
  • Record ID : 30029536
  • Languages: English
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 137
  • Publication date: 2022/05
  • DOI: http://dx.doi.org/10.1016/j.ijrefrig.2022.02.002
  • Document available for consultation in the library of the IIR headquarters only.

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