Numerical investigation of heat transfer and fluid flow characteristics in circular wavy microchannel with tangentially branched secondary channels

摘要

Wavy microchannels have been shown to possess improved heat transfer capabilities because of greater fluid mixing and boundary layer thinning. In this study, fluid flow and heat transfer characteristics of circular wavy microchannels with tangentially branched secondary channels, were numerically investigated. Its heat transfer and fluid flow characteristics were compared with other specific wavy microchannel geometries. Three-dimensional numerical studies were carried out in the Reynolds number range of 100-300 with uniform heat flux wall boundary condition, using Ansys Fluent commercial software. Validation of the model was done with experimental data from literature. Circular wavy microchannels, owing to constant curvature, lead to nearly constant Dean vortices strength. The tangential branched secondary channels helped in further effective fluid mixing and in reinitializing the boundary layer. These phenomena had significant effect on its heat transfer and fluid flow behavior. Circular wavy microchannels with tangentially branched secondary channels, having secondary channel width to primary channel width ratio (omega) equal to 0.25, showed higher overall performance than other designs considered in the present study. Velocity vectors, velocity and temperature contours are presented to explain the fluid flow and heat transfer characteristics. It is observed that circular wavy microchannels with tangentially branched secondary channel design (omega = 0.25) gives 39.36% higher Nusselt number with 21% increased pressure drop as compared to sinusoidal wavy microchannel design. The overall performance factor of circular wavy microchannel with tangentially branched secondary channel design (omega = 0.25) is higher in the Reynolds number range of 100-250 than all other designs considered in this study.