Multi Wall Carbon Nano-Tubes (MWCNT's) are new types of nanoparticles which enhance thermal behavior of the base fluids. These are applicable in automotive engineering. Besides, Micro-polar Nano-fluids are another type of Nano-fluid in which the micro-rotation of the nanoparticles is considered when solving the governing equations. In this study, the natural convection and entropy generation of a Micro-polar MWCNT-Fe₃O₄/Water Hybrid Nano-fluid is investigated. The governing equations which consider the Non-Newtonian behavior of this type of Nano-fluid are solved by FEM. The effcacy of micro-rotation parameter (0–2), Hartmann number (0-20), Rayleigh number (10⁴-10⁶), and inclination angle of the cavity (0°–90°) on the Nusselt number and S is investigated. The findings disclose that both micro-rotation parameter and Hartmann number reduce NC and Nu_avg of hybrid nanofluid. Besides, Be number will increase by reducing Ra number. Moreover, the average of Be number will enhance up to 19% and the Nu_avg will be weakened by 24% by changing the φ from 0° to 90°. Plus, Nu_avg will descend by 27% when the micro-rotation parameter is increased from 0 to 2. This study is mostly applicable in solar collectors, heat exchangers, and biomedical engineering such as blood flow in which the micro-polar flow is present.

多壁碳纳米管 (MWCNT) 是新型纳米颗粒，可增强基础流体的热性能。这些适用于汽车工程。此外，微极性纳米流体是另一种纳米流体，其中在求解控制方程时考虑了纳米粒子的微旋转。在这项研究中，研究了微极性多壁碳纳米管-Fe ₃ O ₄ /水混合纳米流体的自然对流和熵的产生。考虑这种类型的纳米流体的非牛顿行为的控制方程通过有限元法求解。微旋转参数（0-2）、哈特曼数（0-20）、瑞利数（10 ⁴ -10 ^{6 ）的功效}），并研究了腔的倾角（0°-90°）对努塞尔数和 S 的影响。研究结果表明，微旋转参数和哈特曼数都降低了混合纳米流体的 NC 和 Nu _avg。此外，Be 数会随着 Ra 数的减少而增加。此外，通过将 φ 从 0° 更改为 90°，Be 数的平均值将提高 19%，Nu _avg将减弱 24%。此外，当微旋转参数从 0 增加到 2 时，Nu _avg将下降 27%。本研究主要适用于太阳能集热器、热交换器和生物医学工程，例如存在微极流的血流.