Numerical and experimental studies on laminar hydrodynamic and thermal characteristics in fractal-like microchannel networks. Part A: Comparisons of two numerical analysis methods on friction factor and Nusselt number

In this paper, the conventional equivalent method and the subsectional integral method were used to analyze the friction factor and the Nusselt number in fractal-like microchannel networks. The calculated results obtained from the two methods were compared with those obtained from the experimental data. It was proved that for complex configuration of the microchannel, the conventional equivalent method based on the parameters of inlet and outlet has larger deviations than the subsectional integral method developed in the present study. Furthermore, the results from the subsectional integral method were verified to agree well with those from the experiments under different boundary conditions. In addition, the effects of both hydrodynamically and thermally developing flow were taken into considerations since the bifurcations and bends in the fractal-like microchannel networks disturbed the flow and made the developing flow maintain in each branch. And these effects have been included by replacing the Fanning friction factor with the apparent friction factor to account for the frictional and developing flow pressure drops.