Numerical analysis and parametric optimization on flow and heat transfer of a microchannel with longitudinal vortex generators

In this paper, a three dimensional (3D) numerical model of a rectangular microchannel with longitudinal vortex generators (LVGs) is developed. The impacts of length, width, longitudinal spacing, and number of LVG pairs are discussed. To improve the flow and heat-transfer performance, the Taguchi method is employed for optimization. Three evaluation indexes-Nusselt number (Nu), Fanning friction factor (f), and overall efficiency (eta)-are selected. The analysis of the influence degree of the geometric parameters of LVGs are carried out by intuitive analysis of the Taguchi method results, and the optimum combinations of geometric parameters are also determined. Also, the second-order dimensionless correlations involving multiple impact factors are obtained through response surface analysis. Results show that the number and longitudinal spacing of LVG pairs are the main impact factors for Nu. Regarding the flow resistance, the number and length of LVGs have a much stronger influence than other parameters. Two optimum combinations for Nu and overall efficiency are acquired, which achieve a 23.6% and 7.2% increase for Nu and overall efficiency, respectively, compared with the original model. The maximum differences between the correlations and test models are less than 15% for all of the evaluation indexes. The present investigation can be beneficial for the design and optimization of LVGs-enhanced microchannel heat sinks.