基于多相流模型的纳米流体在水平细圆管内强制对流换热数值模拟

运用2种多相流模型模拟了纳米流体在细圆管内的强制对流换热特性,并与已有文献的实验值和传统流体经验公式的计算值进行对比.其中,采用混合模型和欧拉模型分析了雷诺数、纳米颗粒体积分数等物理量对换热特性的影响.结果表明:在纳米颗粒体积分数较低时,模拟值与其实验值及经验公式的计算值相差不大;随着纳米颗粒体积分数增加,其非常规的流体特性逐渐突出,当纳米颗粒体积分数达到一定值时,常规的流体经验公式已不再适用,纳米流体换热呈现出一定的多相流特性,且多相流模型的模拟值更接近于其实验值,表明运用多相流模型能够模拟纳米流体的换热特性.

Numerical Simulation of Forced Convective Heat Transfer and Flow Characteristics of Nanofluids in Small Tubes Using Multiphase Models

The forced laminar and turbulent heat transfer characteristics of nanofluids in small smooth tubes were simulated using two kinds of multiphase-flow models. The simulated results were compared with the experimental results and the traditional predicting equations. The multiphase-flow models include the Euler-Euler model, of which one is the mixture model and the other is Eulerian model, respectively. The effects of various parameters such as Reynolds number and mass concentration of nanoparticles on the heat transfer characteristics were investigated and discussed in each model. The results show that little deviation exists between the simulated results and traditional predicting equations for low concentration nanofluid. While non-traditional fluid characteristics occur and increase with the increase of the nanoparticles concentration of nanofluid, the effect of multiphase flow comes out when concentration reaches a certain value. Besides, the simulated results using special multiphase-flow models are closer to the experimental data than that of the traditional equations.