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首页> 外文期刊>International journal of numerical methods for heat & fluid flow >Two-phase model for mixed convection and flow enhancement of a nanofluid in an inclined channel patterned with heated slip stripes
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Two-phase model for mixed convection and flow enhancement of a nanofluid in an inclined channel patterned with heated slip stripes

机译：用加热滑条图案化厚度混合对流和流量增强的两相模型

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Purpose-The purpose of this study is to analyze the heat transfer and flow enhancement of an Al_2O_3-water nanofluid filling an inclined channel whose lower wall is embedded with periodically placed discrete hydrophobic heat sources. Formation of a thin depletion layer of low viscosity over each hydrophobic heated patch leads to the velocity slip and temperature jump condition at the interface of the hydrophobic patch. Design/methodology/approach-The mixed convection of the nanofluid is analysed based on the two-phase non-homogeneous model. The governing equations are solved numerically through a control volume approach. A periodic boundary condition is adopted along the longitudinal direction of the modulated channel. A velocity slip and temperature jump condition are imposed along with the hydrophobic heated stripes. The paper has validated the present non-homogeneous model with existing experimental and numerical results for particular cases. The impact of temperature jump condition and slip velocity on the flow and thermal field of the nanofluid in mixed convection is analysed for a wide range of governing parameters, namely, Reynolds number (50 ≤ Re ≤ 150), Grashof number (10~3 ≤ Gr ≤ 5 × 10~4), nanoparticle bulk volume fraction (0.01 ≤ Φ_b ≤ 0.05), nanoparticle diameter (30 ≤ d_p ≤ 60) and the angle of inclination (-60° ≤σ ≤ 60°). Findings-The presence of the thin depletion layer above the heated stripes reduces the heat transfer and augments the volume flow rate. Consideration of the nanofluid as a coolant enhances the rate of heat transfer, as well as the entropy generation and friction factor compared to the clear fluid. However, the rate of increment in heat transfer suppresses by a significant margin of the loss due to enhanced entropy generation and friction factor. Heat transfer performance of the channel diminishes as the channel inclination angle with the horizontal is increased. The paper has also compared the non-homogeneous model with the corresponding homogeneous model. In the non-homogeneous formulation, the nanoparticle distribution is directly affected by the slip conditions by virtue of the no-normal flux of nanoparticles on the slip planes. For this, the slip stripes augment the impact of nanoparticle volume fraction compared to the no-slip case. Originality/value-This paper finds that the periodically arranged hydrophobic heat sources on the lower wall of the channel create a significant augmentation in the volume flow rate, which may be crucial to augment the transport process in mini- or micro-channels. This type of configuration has not been addressed in the existing literature.
机译：目的 - 本研究的目的是分析填充倾斜通道的AL_2O_3-水纳米流体的传热和流量增强，其下壁嵌入周期性地放置离散的离散疏水热源。在每个疏水性加热贴片上形成薄耗尽层的低粘度，导致疏水贴片界面处的速度滑移和温度跳转条件。设计/方法/方法 - 基于两相非均质模型分析纳米流体的混合对流。通过控制体积方法，数值解决控制方程。沿着调制通道的纵向采用周期性边界条件。速度滑动和温度跳跃条件与疏水式加热条纹一起施加。本文已验证了本发明的非均质模型，具有特定情况的现有实验和数值效果。在混合对流中的纳米流体中的流动和热场上的影响和热场对混合对流的影响，即雷诺数（50≤Re≤150），格拉夫数（10〜3≤ GR≤5×10〜4），纳米粒子散装体积分数（0.01≤φ_b≤0.05），纳米颗粒直径（30≤d_p≤60）和倾斜角度（-60°≤σ≤60°）。结果 - 加热条纹上方的薄耗尽层的存在降低了传热并增强了体积流速。考虑纳米流体作为冷却剂，增强了传热速率，以及与透明流体相比的熵产生和摩擦因子。然而，由于增强的熵产生和摩擦因子，传热中的增量率抑制了损失的显着边际。当与水平的沟道倾斜角度增加时，通道的传热性能会减小。本文还将非均质模型与相应的均匀模型进行比较。在非均匀的制剂中，纳米颗粒分布通过纳米颗粒上的纳米颗粒上的无正常通量直接受到滑移条件的影响。为此，滑动条纹与无滑箱相比增强了纳米颗粒体积分数的影响。原创性/值 - 本文发现，通道下壁上的周期性地布置疏水热源在体积流量中产生显着的增强，这可能是在微型或微通道中增加运输过程的关键。现有文献尚未解决这种配置。

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