Investigations on viscous dissipation effect of liquid flow in microtubes

The experimental and numerical investigations are carried out to explore the viscous dissipation effect during de-ionized ultra pure water flowing through smooth quartz glass microtubes with inner diameters of 25 and 50 m, and the Reynolds number varies in the range from 0 to 680. The viscous dissipation characteristic in microtubes is numerically calculated by a 2-D model and the Electrical Double Layer (EDL) effect on the flow is considered. A new criterion V (c) demonstrating the law of the viscous dissipation effect in microtubes is summed up with the numerical simulation results. By applying the micro-area thermal-imaging technology and a series of correction tests, the viscous heating temperature increment in the microtube can be exactly measured by an IR camera with a special magnifying lens. Furthermore, the temperature increment of the working fluid due to the heat generated by the pump is also considered in the experimental investigation. The comparisons among the experimental results, the numerical predictions and the new theoretical correlations are made in the present research, which indicates the experimental data are in rough accordance with the numerical and the theoretical results.