半圆形微通道内纳米流体流动与传热特性

Heat Transfer and Flow Characteristics of Nanofluids Flowing through Semicircular Microchannel

为了研究流体流经半圆形微通道的传热与流动特性,对去离子水、Cu-水纳米流体及Al-水纳米流体在21个当量直径为612μm的平行半圆形微通道热沉(微型散热片)中的流动与对流换热特性进行了实验研究。研究发现:与截面为矩形的常规形状相比,半圆形微通道也具有很好的换热效果,与去离子水相比,添加Al和Cu纳米颗粒的纳米流体压降损失增大。当纳米流体的质量浓度为0.5%时,在微通道换热器中的纳米流体效应由于粘度过大等原因发生了恶化,并且这种恶化在高流速下也出现了。根据实验数据得到了半圆形微通道内低浓度纳米流体的层流对流换热以及摩擦阻力系数关联式,对热性能系数的分布曲线进行了综合分析,研究结果对于集成高效芯片散热系统设计具有重要意义。

In order to study the heat transfer and flow characteristics of fluid flowing through the semi-circular microchannel,the convective heat transfer characteristics of deionized water,Cu-water nanofluids and Al-water nanofluids were studied experimentally in the progress of thermal subsidence in 21 semicircular parallel microchannels with 612μm equivalent diameter.Microchannel heat transfer coefficient of thermal subsidence and pressure drop were measured and calculated.The fact that semicircular microchannel heat exchanger also has good heat transfer performance compared to the conventional shape of rectangular cross-section was confirmed by the results.Moreover,compared to deionized water,adding Al and Cu nanoparticles increases the pressure drop.Nanofluids effects in the process of thermal subsidence in microchannels deteriorate due to the accumulation of nanoparticles,precipitate,and the viscosity and other reasons when the concentration of nanofluids is 0.5%.Based on the experimental data,the correlations of laminar convective heat transfer and drag coefficient of low concentration of nanofluids in semicircular microchannel were formulated.The results are of great significance for the integrated chip cooling system design.