An experimental investigation of flow characteristics for laminar flow in silicon microchannels

Investigation on the single-phase liquid flow characteristics in microchannels is very important to the design of the microfluidic devices. Unfortunately, the validity of the conventional fluid flow theories in microchannel fluid flows is still disputed. Under heating condition, experiments were conducted to investigate the single phase liquid flow characteristics in microchannel heat sink. The silicon heat sink consists of 10 parallel triangular microchannels with a hydraulic diameter of 155.3 mu m. Methanol was employed as working fluid in the experiments. The experimental results show that no transition from laminar to turbulent was found in present experiments. All experiments were conducted under laminar conditions, and methanol reached developed condition at the exit of microchannels. Comparison between the present experimental data and the predictions of the conventional theory were carried out, and great deviation was found. The actual reasons of disparity were discussed, including surface roughness effect, wall slip effect, Non-Newtonian fluid effect, entrance effect, electric double layer effect, non-constant fluid properties, and viscous dissipation effects. The entrance effect may be the most important reason for the discrepancy. Based on the present experimental data, a new correlation for the apparent friction constant was given, which can predict present experimental data very well.