Experimental investigation on fluid mechanics of micro-channel heat transfer devices

•Heat transfer and fluid flow in micro-channels are investigated.•Two serpentine cells are considered and compared with a straight parallel channel.•In order to improve the efficiency of the cells different flow conditions are studied.•Thermal behavior is evaluated on the Nu-Re diagram and through efficiency parameters.•µPIV measurements were performed to detail the observed global thermal performances. The future technological horizons for engineering applications (Automotive, Energy, Bio-Engineering) require the use of limited size heat exchangers with high efficiency. In the present work, the flow field in small scale channels of different geometries is investigated experimentally using µPIV (micro Particle Image Velocimetry) and thermal measurements. The Reynolds number in the channels is changed as also the wall temperature, in order to investigate and improve the thermal efficiency at different flow rates, temperatures and geometrical configurations. The main result of this investigation is that a serpentine cell attains the highest efficiency regardless of flow regime, getting high Nusselt numbers combined with low pressure losses, as derived by the observation of quite high local velocities and few recirculation regions.