Flow and heat transfer characteristics in rough micro-channels

摘要

Flow and heat transfer in micro-channels have an important influence on core design and roughness elements have an important influence on flow and heat transfer characteristics of fluids in micro-channels. A fluid flow and heat transfer model has been adopted for water in rough micro-channels. Various studies are conducted for determining the influence of roughness on the entrance length, flow transition, flow resistance and heat transfer, followed by a theoretical treatment on the undergoing mechanism of roughness on flow and heat transfer. The results show that the entrance length is mainly affected by Reynolds number in rough micro-channels. Due to instigation of turbulence in axial and radial velocities, the roughness elements lead to flow transition ahead of time. Poiseuille number increases with the increase of Reynolds number, as well as with the decrease in gap spacing of micro-channels. Using roughness elements, a smaller gap spacing tends to enhance the heat transfer effect. When the relative spacing is large, roughness elements tend to reduce the heat transfer effect.