This article presents friction factor and heat transfer coefficient experimental results obtained with a liquid flow of R134a in rectangular mini-channels. Two test sections made of aluminium multi-port extruded (MPE) tubes (channels dimensions 1.11 × 1.2

In this study, the heat transfer characteristics of single-phase forced convection of R134a through single circular micro-channels with 1.7, 1.2, and 0.8 mm as inner diameters were investigated experimentally. The results were compared both to correlations for the heat transfer in macroscale channels and to correlations suggested for microscale geometries. The results show good agreement between the classical correlations and the experimentally measured data in the turbulent region. Contrary, none of the suggested correlations for microchannels, agreed with the test data. In the laminar regime, the heat transfer coefficients were almost identical for all three diameters.