Heat Transfer and Pressure Drop During HC-600a (Isobutane) Condensation Inside a Brazed Plate Heat Exchanger

This paper presents the heat transfer coefficients and the pressure drop measured during HC-600a (Isobutane) condensation inside a brazed plate heat exchanger: the effects of saturation temperature, refrigerant mass flux and vapour super-heating are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux. At low refrigerant mass flux (< 18 kg/m2s) the heat transfer coefficients are not dependent on mass flux and condensation is controlled by gravity. For higher refrigerant mass flux (> 18 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 3 to 8% 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.