Abstract

This paper describes the results of experimental investigations of heat transfer during the condensation of the homogenous R134a refrigerant and zeotropic mixtures R404A, R407C and R410A in pipe minichannels with internal diameters 0.31–3.30 mm. The values of the local and average heat transfer coefficient throughout the range of changes in the vapor quality 1–0 were determined. Based on the obtained results, the effect of vapor quality, mass flux density and channel diameter changes on heat transfer coefficient was illustrated. a pronounced effect of the refrigerant properties at the heat exchange efficiency during the condensation process in pipe minichannels was indicated. The results were compared with calculations according to the correlations proposed by other authors. On the basis of the experimental investigations, the authors proposed their own correlation for the calculation of local heat transfer coefficient, obtaining the results of compatibility tests in the range of ±20%.