Purpose

The purpose of this paper is to analyze the thermal, hydraulic and entropy generation characteristics for the magneto-hydrodynamic (MHD) pressure-driven flow of Al₂O₃-water nanofluid through an asymmetric wavy channel.

Design/methodology/approach

Galerkin finite element method is used to solve the governing transport equations numerically within the computational domain using the appropriate boundary conditions. The temperature and flow fields are computed by varying Reynolds number (Re), Hartmann number (Ha) and nano-particle volume fraction (ϕ) in the following range: 10 ≤ Re ≤ 500, 0 ≤ Ha ≤ 75 and 0 ≤ ϕ ≤ 5%.

Findings

The formation of the recirculation zones in the wavy passages, the size of it and the strength of the vortices formed can be modulated by the application of the magnetic field. The overall heat transfer rate increases with Ha for all ϕ both for a lower and higher regime of Re although the enhancement is more for lower values of Re and nanofluids as compared to base fluid and for intermediate values of Re, the effect of a magnetic field is almost insignificant. The magnetic performance factor (PF_magnetic) decreases with Ha although the rate of decrement varies with Re. The increase ϕ also enhances PF_magnetic especially at lower and higher values of Re. The addition of nano-particle enhances the entropy generation at lower values of the Re, while the opposite effect is seen for higher values of Re.

Practical implications

The present study has enormous practical relevance for the design of heat exchanger applied for solar collectors, process plants, textile and aerospace applications.

Originality/value

The combined effects on the heat transfer rate and the associated pressure drop penalty due to the applied magnetic field for the flow of nanofluid through an asymmetric wavy channel have not been reported to date. The effect of the magnetic field on the formation of recirculation zones and hot spot intensity in the asymmetric wavy channel has been examined in detail. The PF_magnetic is investigated first time for the MHD nanofluid flow through a wavy channel.

中文翻译：

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磁流体动压驱动纳米流体通过不对称波浪通道的热工和熵生成分析

目的

本文的目的是分析Al ₂ O _3-水纳米流体通过不对称波浪通道的磁流体动力学（MHD）压力驱动流的热，水力和熵产生特性。

设计/方法/方法

Galerkin有限元方法用于使用适当的边界条件在计算域内数值求解控制输运方程。的温度和流场通过改变雷诺数（Re），哈特曼数（HA）和纳米颗粒体积分数（计算φ 10≤重新≤500，0≤哈≤75和0≤：在下面的范围内）φ ≤ 5％。

发现

波浪通道中回流区的形成，其大小和形成的涡旋强度可以通过施加磁场来调节。对于较低的Re和较高的Re态，所有ϕ的总传热率均随Ha的增加而增加，尽管与基础流体相比，对于较低的Re和纳米流体值和相对中等的Re值，磁场的影响更大。几乎是微不足道的。磁性能因数（PF_磁性）随Ha降低，尽管递减率随Re改变。ϕ的增加也增强了PF_磁特别是在较低和较高的Re值下。纳米粒子的添加在较低的Re值下增强了熵的产生，而对于较高的Re值则看到了相反的效果。

实际影响

本研究对于应用于太阳能集热器，加工厂，纺织和航空航天应用的热交换器的设计具有巨大的现实意义。

创意/价值

迄今为止，尚未报道由于纳米流体流过不对称波浪通道而施加的磁场对传热速率和相关的压降损失的综合影响。详细研究了磁场对非对称波浪通道中回流区形成和热点强度的影响。所述PF_磁性进行了研究首次为MHD纳米流体流过波纹通道。