Purpose

This study aims to undertake a comprehensive examination of heat transfer by convection in porous systems with top and bottom walls insulated and differently heated vertical walls under a magnetic field. For a specific nanofluid, the study aims to bring out the effects of different segmental heating arrangements.

Design/methodology/approach

An existing in-house code based on the finite volume method has provided the numerical solution of the coupled nondimensional transport equations. Following a validation study, different explorations include the variations of Darcy–Rayleigh number (Ra_m = 10–10⁴), Darcy number (Da = 10^–5–10^–1) segmented arrangements of heaters of identical total length, porosity index (ε = 0.1–1) and aspect ratio of the cavity (AR = 0.25–2) under Hartmann number (Ha = 10–70) and volume fraction of φ = 0.1% for the nanoparticles. In the analysis, there are major roles of the streamlines, isotherms and heatlines on the vertical mid-plane of the cavity and the profiles of the flow velocity and temperature on the central line of the section.

Findings

The finding of a monotonic rise in the heat transfer rate with an increase in Ra_m from 10 to 10⁴ has prompted a further comparison of the rate at Ra_m equal to 10⁴ with the total length of the heaters kept constant in all the cases. With respect to uniform heating of one entire wall, the study reveals a significant advantage of 246% rate enhancement from two equal heater segments placed centrally on opposite walls. This rate has emerged higher by 82% and 249%, respectively, with both the segments placed at the top and one at the bottom and one at the top. An increase in the number of centrally arranged heaters on each wall from one to five has yielded 286% rate enhancement. Changes in the ratio of the cavity height-to-length from 1.0 to 0.2 and 2 cause the rate to decrease by 50% and increase by 21%, respectively.

Research limitations/implications

Further research with additional parameters, geometries and configurations will consolidate the understanding. Experimental validation can complement the numerical simulations presented in this study.

Originality/value

This research contributes to the field by integrating segmented heating, magnetic fields and hybrid nanofluid in a porous flow domain, addressing existing research gaps. The findings provide valuable insights for enhancing thermal performance, and controlling heat transfer locally, and have implications for medical treatments, thermal management systems and related fields. The research opens up new possibilities for precise thermal management and offers directions for future investigations.

中文翻译：

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在恒强磁环境中填充混合纳米流体的多孔系统中面向垂直壁的多段加热

目的

本研究旨在对具有顶壁和底壁绝缘以及磁场下不同加热的垂直壁的多孔系统中的对流传热进行全面检查。对于特定的纳米流体，该研究旨在揭示不同分段加热布置的效果。

设计/方法论/途径

基于有限体积法的现有内部代码提供了耦合无量纲输运方程的数值解。经过验证研究，不同的探索包括达西-瑞利数 (Ra _m = 10–10 ⁴ )、达西数 (Da = 10 ^–5 –10 ^–1 )的变化、相同总长度的加热器分段布置、孔隙率指数 ( ε = 0.1–1) 和哈特曼数 (Ha = 10–70) 下空腔的纵横比 (AR = 0.25–2) 和纳米颗粒体积分数φ = 0.1%。在分析中，腔体垂直中平面上的流线、等温线和热线以及截面中心线上的流速和温度分布起着主要作用。

发现

_{随着 Ra m}从 10 增加到 10 ^{4 ，}传热速率单调上升的发现促使我们进一步比较 Ra _m等于 10 ⁴时的传热速率，同时在所有情况下加热器的总长度保持恒定。对于整个墙壁的均匀加热，该研究揭示了放置在相对墙壁中央的两个相等的加热器段的显着优势，即加热率提高了 246%。这一比率分别高出 82% 和 249%，两个细分市场都位于顶部，一个位于底部，一个位于顶部。每面墙上集中布置的加热器数量从 1 个增加到 5 个，效率提高了 286%。腔体高度与长度之比从 1.0 变化到 0.2 和 2 会导致该速率分别下降 50% 和增加 21%。

研究局限性/影响

对附加参数、几何形状和配置的进一步研究将巩固理解。实验验证可以补充本研究中提出的数值模拟。

原创性/价值

这项研究通过将分段加热、磁场和混合纳米流体集成到多孔流域中，解决了现有的研究空白，为该领域做出了贡献。这些发现为增强热性能和控制局部传热提供了宝贵的见解，并对医疗、热管理系统和相关领域产生影响。该研究为精确热管理开辟了新的可能性，并为未来的研究提供了方向。