关键词: 分形, 换热器, 流动, 传热, 均温性

Abstract: A three-dimensional (3D) steady model for heat transfer and laminar fluid flow in fractal tree-like channel heat sink is developed. The laminar convective heat transfer in the fractal tree-like channel heat sink with an inlet hydraulic diameter of 4 mm for rectangular cross-section is numerically simulated by liquid-solid coupling numerical method. The significant heat transfer enhancement mechanism by the bifurcations and the temperature distribution on heating surface is discussed in detail. The results indicate that the secondary flow motion generated at bifurcations can effectively enhance heat transfer. Fractal tree-like channel heat sink has obvious advantages over the traditional serpentine flow pattern in both heat transfer and pressure drop. Under the same inlet Reynolds number, the maximum temperature difference on the surface of fractal tree-like channel heat sink is far less than that of serpentine flow pattern; the pressure drop of laminar fluid flow in fractal tree-like channel is less than that in serpentine channel by over 50%. In addition, a fractal tree-like channel heat sink and a serpentine channel heat sink are respectively designed and fabricated to conduct the verification experiment for numerical simulation. The temperature distribution and pressure drop measured by experiment are in a good agreement with those obtained by numerical simulation, which verifiesed that the proposed 3D model is reliable.

Key words: fractal, heat sink, fluid flow, heat transfer, temperature uniformity