Friction factor and heat transfer coefficient of R134a liquid flow in mini-channels

This article presents an experimental study of friction factor and heat transfer coefficient for a vertical liquid up-flow of R134a. A flat aluminium multiport extruded tube composed of 11 parallel rectangular channels (3.28 mm×1.47 mm) with hydraulic diameter of 2.01 mm was used. Mass flux ranges from 28 to 800 kg m−2 s−1 and heat flux from 0.84 to 22 kW m−2. Working pressure is around 2000 kPa and inlet subcooling around 70 K. The results were compared with those found in the literature for conventional tubes and mini-channels, and discussed.