Mahmud Tawsif, Chowdhury Taha, Nag Preetom, Molla Md Mamun
Department of Mathematics & Physics, North South University (NSU), Dhaka, Bangladesh.
Center of Applied & Computational Sciences (CACS), NSU, Dhaka, Bangladesh.
Heliyon. 2024 Aug 3;10(15):e35523. doi: 10.1016/j.heliyon.2024.e35523. eCollection 2024 Aug 15.
This article investigates the convective thermal and solutal exchange from the active walls of a trapezium chamber which is filled with multi-walled carbon nanotubes (MWCNT)-silicon dioxide (SiO)-ethylene glycol-water hybrid nano-coolant. The hybrid nano-coolant exhibits non-Newtonian shear-thinning rheology and is modeled by the power-law viscosity as per an exploratory report. The convection is generated by both the thermal and solutal buoyancy forces in the presence of a magnetic field. Thermophysical properties of the particular nano-coolants are estimated from the temperature-dependent empirical correlation. An in-house FORTRAN code based on the finite volume method (FVM) has been utilized to simulate the non-dimensional controlling equations representing the physical model. By systematically varying the strength of the magnetic field ( ) and its direction ( ), the volume fraction of nano-coolant ( ) and solutal-to-thermal buoyancy ratio ( ), we thoroughly analyzed their impact on the flow field, thermal, and solutal transmission behavior. Significant impacts arising from the shear-thinning nature ( ) of the nano-coolant were observed, influencing both thermal and solutal transfer rates as reflected in the Nusselt number () and Sherwood number (). The impact of on and is more substantial for than the case . The investigation exposed that when the average ( ) for nano-ccolants ( ) is maximally enhanced by 80% for compared to the case . For the same nano-coolant with and , there is a 128% elevation in the average Sherwood number ( ) when compared to . The entropy generation ( ) inherent to the heat and mass transfer process and hence a criterion ( ) is computed to address the system thermal performance from the thermodynamics second law. increased as was reduced, indicating that the shear-thinning effect contributed strongly to the entropy generation.
本文研究了梯形腔活性壁的对流热交换和溶质交换，该梯形腔内充满了多壁碳纳米管（MWCNT）-二氧化硅（SiO）-乙二醇-水混合纳米冷却剂。根据一份探索性报告，该混合纳米冷却剂表现出非牛顿剪切变稀流变学特性，并采用幂律粘度进行建模。对流是由磁场存在下的热浮力和溶质浮力共同产生的。特定纳米冷却剂的热物理性质通过与温度相关的经验关联式估算。基于有限体积法（FVM）的内部FORTRAN代码已被用于模拟代表物理模型的无量纲控制方程。通过系统地改变磁场强度（ ）及其方向（ ）、纳米冷却剂的体积分数（ ）和溶质与热浮力比（ ），我们全面分析了它们对流场、热传递和溶质传递行为的影响。观察到纳米冷却剂的剪切变稀特性（ ）产生了显著影响，影响了热传递和溶质传递速率，这在努塞尔数（ ）和舍伍德数（ ）中得到体现。与 情况相比， 对 和 的影响在 时更为显著。研究表明，当 时，与 情况相比，纳米冷却剂（ ）的平均 （ ）最大可提高80%。对于相同的纳米冷却剂，当 时，平均舍伍德数（ ）与 相比提高了128%。计算了传热传质过程中固有的熵产生（ ），并因此计算了一个准则（ ），以从热力学第二定律的角度评估系统的热性能。随着 的减小， 增加，表明剪切变稀效应强烈地促进了熵产生。
