Key
2128
Conference Year
2012
Keywords
HFO refrigerants, Condensation, Heat Transfer, Pressure Drop
Abstract
This paper presents the heat transfer coefficients and the pressure drop measured during HFO1234yf condensation inside a brazed plate heat exchanger: the effects of saturation temperature, refrigerant mass flux and vapour superheating are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux. At low refrigerant mass flux (< 20 kg/m2s) the heat transfer coefficients are not dependent on mass flux and condensation is controlled by gravity. For higher refrigerant mass flux (> 20 kg/m2s) the heat transfer coefficients depend on mass flux and forced convection condensation occurs. The condensation heat transfer coefficients of super-heated vapour are from 8 to 11% higher than those of saturated vapour. 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. HFO1234yf exhibits heat transfer coefficients lower (10-12%) and frictional pressure drop lower (10-20%) than those of HFC134a under the same operating conditions.