The current work aims to perform the hydrothermal and entropy generation (EG) characteristics in a naturally cooled eccentric horizontal annulus filled with non‐Newtonian water‐magnetite/CNT nanofluid (NF). The wall temperature of both cylinders is constant and the temperature of the outer cylinder is lower than that of the inner cylinder. The impacts of vertical eccentricity, nanoadditive concentration (φ) and Rayleigh number ( $Ra$) on the first and second‐laws performance features of the annulus are investigated numerically. It was found the average Nusselt number ( $Nu$), the global thermal EG (TEG) and the global frictional EG (FEG) augment with boosting both the $Ra$ and φ. In addition, it was depicted that the negative eccentricity is desirable and undesirable from the perspective of the first and second‐laws of thermodynamics. Moreover, the outcomes revealed that the first‐law/second‐law performance of the aqueous magnetite/CNT NF is better/weaker than that of the aqueous magnetite NF. Furthermore, for all the examined cases, the TEG rates are much higher than the FEG rates, and as a result, the pattern of total EG changes follows the TEG. Among all the studied cases, the minimum total EG was 4 W/K, which belonged to the case of ${\phi }_M$= 0.9%, ${\phi }_{CNT}$= 0%, $Ra$= 10³ and $e$= 0.001.

中文翻译：

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从热力学第一定律和第二定律的角度看，非牛顿纳米流体在偏心环空中的自由对流

当前的工作旨在在充满非牛顿水磁铁矿/ CNT纳米流体（NF）的自然冷却的偏心水平环中执行水热和熵生成（EG）特性。两个气缸的壁温是恒定的，外气缸的温度低于内气缸的温度。垂直偏心距，纳米添加剂浓度（φ）和瑞利数（$\mathrm{[R}\mathrm{一种}$）对环的第一定律和第二定律的性能特征进行了数值研究。发现平均努塞尔特数（$ñü$），整体热电EG（TEG）和整体摩擦电EG（FEG）随着 $\mathrm{[R}\mathrm{一种}$和φ。另外，从热力学的第一定律和第二定律的角度来看，负偏心率是理想的，而理想的是不理想的。此外，结果表明磁铁矿/ CNT NF的第一律/第二律性能比磁铁矿NF的更好/更弱。此外，对于所有检查的病例，TEG的发生率远高于FEG的发生率，因此，总EG的变化模式遵循TEG。在所有研究案例中，最小总EG为4 W / K，属于${\phi }_{\mathrm{中号}}$= 0.9％， ${\phi }_{CñŤ}$= 0％， $\mathrm{[R}\mathrm{一种}$= 10 ³并且$Ë$= 0.001。