Two-phase heat transfer of low gwp ternary mixtures.

Number: 210049



Refrigerant blends obtained mixing hydrofluorocarbons (HFC) and hydrofluoroolefins (HFO) have recently been proposed as substitutes for high GWP (Global Warming Potential) fluids employed in refrigeration and airconditioning systems. As a general trend, the dimension of pipes used in heat exchangers is decreasing: diameters around 5 mm are often employed in finned-tube coil heat exchangers and minichannels heat exchangers (with internal diameter around 1-2 mm) are also a common solution for the automotive sector and for air-cooled chillers. Condensation and flow boiling heat transfer coefficients of zeotropic ternary mixtures R455A (R32, R1234yf and R744 at 21.5/75.5/3.0% by mass composition) and R452B (R32, R1234yf and R125 at 67.0/26.0/7.0% by mass composition) have been measured inside a minichannel (0.96 mm diameter) and inside a conventional tube (8.0 mm diameter). R455A exhibits a temperature glide around 10 K at 35 °C bubble temperature whereas R452B presents a temperature glide around 1 K at 40 °C bubble temperature. The experimental results are compared with selected correlations for condensation and flow boiling heat transfer which account for the additional mass transfer resistance occurring during two-phase heat transfer of zeotropic mixtures. It emerges the importance of including the mass transfer resistance for the prediction of heat transfer coefficient when considering high temperature-glide mixtures.

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  • Original title: Two-phase heat transfer of low gwp ternary mixtures.
  • Record ID : 30028613
  • Languages: English
  • Subject: HFCs alternatives
  • Source: 2021 Purdue Conferences. 18th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2021/05
  • Document available for consultation in the library of the IIR headquarters only.


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