Optimization of design parameters for heat transfer and friction factor in a heat sink with hollow trapezoidal baffles

The aim of this study is to optimize the design parameters of a heat sink on which hollow trapezoidal baffles are mounted on the bottom surface by using Taguchi experimental-design method. The Nusselt number and the friction factor are considered as performance parameters. An orthogonal array is selected as experimental plan for the six parameters: the corner angle (alpha), the inclination angle (beta), the baffle height (H), the baffle length (L), the baffle width (S) and Reynolds number. First of all, each goal has been optimized, separately. Then, all the goals have been optimized together, considering the priority of the goals. The length of the baffle is found to be the most influential parameter on the friction factor. This can be attributed the enhanced effect of longitudinal vortices with baffle length in flow direction. Likewise, it is demonstrated that the most effective parameter on the heat transfer is Reynolds number. The results show that the baffle width (S) and the corner angle (alpha) have insignificant effect on Nusselt number. The maximum heat transfer was obtained at Re = 17,000, H = 36 mm, L = 45 mm, S = 26 mm, alpha = 0 degrees, beta = 0 degrees. The inclination angle (beta) and the baffle height (H) have nearly no effect on the friction factor. The minimum friction factor was obtained at Re = 17,000, H = 20 mm, L = 25 mm, S = 26 mm, alpha = 16 degrees, beta = 0 degrees. The inclination angle (beta) and the baffle height (H) have nearly no effect on the friction factor. It can be concluded that the higher heat transfer rates can be achieved with lower pressure drop penalty with this type of vortex generator in particular configurations.