Two phase flow pressure drop in multiport mini-channel tubes using R134a and R32 as working fluids

In this study, two-phase flow pressure drop was experimentally measured in condensation and evaporation fluid flow. Refrigerants R134a and R32 were tested in a multiport extruded aluminium tube (MPEs) with hydraulic diameters of 0.715 and 1.16 mm. Experimental conditions were in a range: mass velocity 200-1229 kg/m2s, heat flux 2.55-70 kW/m2, saturated temperatures (5,7.5,12.5,30,35,40,45,50,55) °C. To do so, two installations have been used. They were constructed at the Technical University of Cartagena Spain, for the study of boiling and condensation in tubes. They are briefly described in this paper jointly with the experiments performed. The experimental data are compared with some well-known correlations which were developed for macro/mini-channel tubes. The homogeneous mixture model slightly underestimates the experimental boiling data. Classic macro-channel correlations: Friedel and Müller-Steinhagen and Heck predict satisfactorily well our experimental pressure drop data. Some of the new correlations specially developed for mini/micro-channels have been tested, finding that Cavallini et al. and Zhang and Webb predict with reasonable accuracy the experimental two-phase flow pressure drop data.