Experimental and theoretical investigation on condensation inside and outside enhanced tubes.

This work presents new correlations to compute the heat transfer coefficient during refrigerant condensation both inside and outside enhanced tubes. Inside augmented tubes considered include low-fin, micro-fin and cross-grooved, while four different three-dimensional finned tubes have been considered for outside condensation. The models proposed are able to reproduce available experimental data relative to condensation of pure refrigerants and also refrigerant mixtures with a fair accuracy. The paper also presents an experimental rig specifically designed to measure heat transfer coefficients and pressure drop during condensation of zeotropic refrigerant mixtures inside enhanced tubes.