Abstract:

Flow and convective heat transfer characteristics of the triangle micro pin fins (d=247 μm, H=500 μm) using de-ionized water as working fluid were experimentally investigated. The change rules of pressure drops, friction factors and Nusselt numbers etc. in triangular micro pin fins were measured when Reynolds number changed from 0—1000 with different heating power of 50, 100 and 150W, respectively. In addition, the influence of heating power on flow resistance and convective heat transfer of triangular micro pin fins was analyzed. The experimental results illustrated that the friction factors of the triangle micro pin fins increase markedly with the increase of heating power at Re<250 and the increment of friction factors reached more than 200%, while the effect of heating power was significantly reduced at Re>250 and the value of f almost no longer changed with increasing heating power after Re>600. The convective heat transfer in triangular micro pin fins was enhanced by increasing heating power at Re<250 and the increment of Nusselt number at the same Re could reach more than 75%. However, this enhancement was weakened by the vertex evolution in wake zones of triangular micro pin fins and the Nu became smaller with the increase of heating power when Re>250.

Key words: micro pin fins, heating power, Reynolds number, friction factor, Nusselt number, flow, convection, experimental validation

摘要：

建立了三角形微肋阵对流换热性能测试系统, 以去离子水为工质对三角形微肋阵(d=247 μm, H=500 μm)的流动及对流换热特性进行了实验研究, 测试并得到了去离子水流经三角形微肋阵时压力降、阻力系数f及Nusselt数(Nu)等参数在不同Reynolds数(Re)及加热功率P下的变化规律, 分析了加热功率对于三角形微肋阵流动阻力及对流换热特性的影响机理。实验结果表明, Re为0~250范围内, 随加热功率增加三角形微肋阵阻力系数明显增大, 增加幅度最高可达200%以上;当Re>250时, 不同加热功率对阻力系数的影响显著减弱;而当Re>600时, 阻力系数几乎不再随加热功率增加而发生变化。当Re<250时, 随加热功率增加三角形微肋阵Nu逐渐增大, Nu增加幅度最高可达75%以上, 即加热功率增加可以强化对流换热;然而当Re>250时, 受三角形背风区旋涡演变的影响, Nu随加热功率增加而逐渐减小。

关键词: 微肋群, 加热功率, Reynolds数, 摩擦阻力系数, Nusselt数, 流动, 对流, 实验验证