Effect of nanoparticle shapes on nanofluid mixed forced and thermocapillary convection in minichannel
Effect of nanoparticle shapes on nanofluid mixed forced and thermocapillary convection in minichannel
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DOI：
10.1016/j.icheatmasstransfer.2020.104884
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发表时间：
2020-11
影响因子：
7
通讯作者：
Yanni Jiang;Xiaoming Zhou;Yang Wang
中科院分区：
文献类型：
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作者：
Yanni Jiang;Xiaoming Zhou;Yang Wang
为了揭示纳米颗粒形状对微小通道内纳米流体对流沸腾换热性能的影响，采用两相混合模型数值模拟了纳米流体强迫流动与气泡热毛细对流在微小通道内的耦合。首先，揭示了不同形状的纳米颗粒(球形、砖形、叶片形、圆柱形和片状)在微通道内混合强迫对流和热毛细对流的流动特性和强化换热机理。其次，分析了热毛细管和强迫流动对换热的贡献，给出了努塞尔数和总熵产生与纳米颗粒浓度的关系。最后，对不同形状纳米颗粒在微通道内的流动换热性能进行了评价。结果表明，纳米颗粒的形状可以有效地影响热毛细管射流的结构，进而影响气泡附近的热输运。对于球形纳米粒子的纳米流体，热毛细管喷射结构最大，其次是砖形、叶片形、圆柱形和片状纳米粒子。当纳米颗粒体积分数为0.05时，具有叶片状纳米颗粒的纳米流体的热传递性能最好，与球形纳米颗粒的纳米流体相比，平均努塞尔数提高了8.3%。
To reveal the influence of nanoparticle shapes on thermal transport performance of nanofluid convective boiling flow in minichannel, nanofluid forced flow coupled with gas bubble thermocapillary convection in minichannel is numerically investigated by two-phase mixture model. Firstly, the flow characteristics and heat transfer enhancement mechanism of mixed forced and thermocapillary convection in minichannel with different shaped nanoparticles (sphere, brick, blade, cylinder and platelet shaped particles) is disclosed. Secondly, the contribution of thermocapillary and forced flow to heat transfer is analyzed, and the relation of Nusselt number and total entropy production with nanoparticle concentration are given. Finally, the heat transfer performance of nanofluid flow with different shaped nanoparticles in minichannel is evaluated. The results show that, nanoparticle shape can effectively influence thermocapillary jet structure, and then affect the thermal transport at the vicinity of bubble. For nanofluid with spherical nanoparticle the thermocapillary jet structure is the largest, which is followed by brick, blade, cylinder and platelet shaped nanoparticles. The thermal transport performance of nanofluid with blade-shaped nanoparticle is the best, and the average Nusselt number is improved by 8.3% compared with that of nanofluid with spherical nanoaprticle as nanoparticle volume fraction is 0.05.