Appraising conjugate heat transfer, heatlines visualization and entropy generation of Ag-MgO/H 2 O hybrid nanofluid in a partitioned medium

• Published in: International journal of numerical methods for heat & fluid flow Vol. 30; no. 10; pp. 4529 - 4562
• Main Authors: Ferhi, Mokhtar, Djebali, Ridha
• Format: Journal Article
• Language: English
• Published: 25.08.2020
• ISSN: 0961-5539
• DOI: 10.1108/HFF-10-2019-0749

Purpose This paper aims to perform the lattice Boltzmann simulation of conjugate natural convection heat transfer, heat flow visualization via heatlines approach and entropy generation in a partitioned medium filled with Ag-MgO (15-85%)/water. Design/methodology/approach The lattice Boltzmann method (LBM) is used to predict the dynamic and thermal behaviors. Experimental correlations for dynamic viscosity and thermal conductivity versus solid volume fraction are used. The study is conducted for the ranges of Rayleigh number 10 3 ≤ Ra ≤ 10 6 , the partitioner thickness 0.01 ≤ δ ≤ 0.9, its position 0.15 ≤ X s ≤ 0.85 and the hybrid nano-suspensions volume fraction 0% ≤ ϕ ≤ 2%. Findings The effects of varying of controlling parameters on the convective flow patterns, temperature contours, heat transfers, the heatlines and the entropy generation are presented. It has been found that the maximum rate of heat transfer enhancement occurs for low Ra numbers (10 3 ) and is close to 13.52%. The solid thickness d and its horizontal position X s have a substantial influence on the heat transfer rate, flow structure, heatline, total entropy generation and Bejan number. Besides, the maximum heat transfer is detected for high Ra and δ ≈ 1 and the percentage of augmentation is equal to 65.55% for ϕ = 2%. According to the horizontal position, the heat transfer remains invariant for Ra = 10 3 and takes a maximum value near the active walls for Ra ≥ 10 4 . The total entropy generation increases with Ra and decreases with ϕ for Ra = 10 6 . The increase of ϕ from 0 to 2% leads to a reduction in close to 40.76%. For this value of Ra, the entropy is the maximum for δ = 0.4 and X s = 0.35 and X s = 0.65%. Moreover, as the Ra increases the Bejan number undergoes a decrease. The Bejan number is the maximum for Ra = 10 3 independently to δ and X s . The superior thermal performance manifests at low Ra and high value of δ independently to the positions of the conducting body. Originality/value The originality of this paper is to analyze the hybrid nano-additive effects on the two-dimensional conjugate natural convection in a partitioned medium using the LBM. The experimental correlations used for the effective thermal conductivity and dynamic viscosity give credibility to our study. Different approaches such as heatlines and entropy generation are used.