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Heat transfer and pressure drop during HFC-134a condensation inside a commercial brazed plate heat exchanger.

Author(s) : LONGO G. A., GASPARELLA A.

Summary

This paper presents the experimental tests on HFC-134a condensation inside a commercial brazed plate heat exchanger: the effects of refrigerant mass flux, saturation temperature and vapour super-heating are investigated. The experimental results are reported in terms of refrigerant side heat transfer coefficients and frictional pressure drop. At low refrigerant mass flux (< 20 kg/m2.s) the heat transfer coefficients for saturated vapour are not dependent on mass flux and are well predicted by the Nusselt (1916) analysis for vertical surface: the condensation process is gravity controlled. For higher refrigerant mass flux (> 20 kg/m2.s) the heat transfer coefficients depend on mass flux and are well predicted by the Akers et al. (1959) equation: forced convection condensation occurs. In the forced convection condensation region the heat transfer coefficients show a 30% increase for a doubling of the refrigerant mass flux. The condensation heat transfer coefficients of super-heated vapour are 8-10% higher than those of saturated vapour. The heat transfer coefficients show weak sensitivity to saturation temperature. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow and therefore a quadratic dependence on the refrigerant mass flux.

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Pages: ICR07-B1-297

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Details

  • Original title: Heat transfer and pressure drop during HFC-134a condensation inside a commercial brazed plate heat exchanger.
  • Record ID : 2007-2536
  • 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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