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Domestic stack is considered to investigate the double‐diffusive laminar natural convection. The working fluid is a gaseous mixture that has similar physical properties to carbon dioxide. Knowing the patterns of gaseous mixture distribution and determining the carbon deposit regions can help in carbon capture problems. The present study uses the finite element method to numerically examine the double ratio‐diffusive physical phenomena in a rectangular‐trapezoidal enclosure and to simulate the stack under a wide range of dimensionless parameters, such as buoyancy ratio 1≤NBR≤7 $1\le {N}_{{BR}}\le 7$, Lewis number 2≤Le≤8 $2\le {Le}\le 8$, and Rayleigh number 103≤Le≤105 ${10}^{3}\le {Le}\le {10}^{5}$ for different aspect ratios. Nine different cases of the geometrical ratio are selected to cover most possible design configurations. The results indicate that increasing the Lewis number leads to augmented solutal transport but reduces heat transfer. However, both heat and mass transfer are observed by increasing the buoyancy ratio. It is worth mentioning that increasing the ratio of upper side length to base length dD $\left(\frac{d}{D}\right)$ from 14 $\left(\frac{1}{4}\right)$ to 38 $\left(\frac{3}{8}\right)$ leads to a significant increase in mass transfer by 75% and heat transfer enhancement ratio by around 50%. [ABSTRACT FROM AUTHOR]

In line with recent studies, where it has been shown that nanofluids containing graphene have a stronger capacity to boost the heat transfer coefficient with respect to ordinary nanofluids, experiments have been conducted using water with cobalt ferrite/graphene nanoparticles. In particular, a circular channel made of copper subjected to a constant heat flux has been considered. As nanoparticles are sensitive to the presence of a magnetic field, different conditions have been examined, allowing both the strength and the frequency of such a field to span relatively wide ranges and assuming different concentrations of nanoparticles. According to the findings, the addition of nanoparticles to the fluid causes its rotation speed to increase by a factor of two, whereas ultraviolet radiation plays a negligible role. The amount of time required to attain the maximum rotation speed of the nanofluid and the Nusselt number have been measured under both constant and alternating magnetic fields for a ferrofluid with a concentration of 0.5% and at flow Reynolds number of 550 and 1750. [ABSTRACT FROM AUTHOR]

The present work focuses on investigating magnetohydrodynamic (MHD) natural convection in a complex I-shaped enclosure with corrugated walls, filled with nanofluid and porous media layers. This study analyzes various parameters’ effects on heat transfer and fluid flow. The enclosure’s left and right walls maintain low temperatures, while the other walls are insulated. The inner corrugated cylinder experiences high temperatures. The study examines the impact of Rayleigh number (Ra), Hartman number (Ha), nanofluid volume fraction (φ), Darcy number (Da), MHD inclination angle (γ ), position of the corrugated cylinder (δ) and number of undulations (N) on isotherms, streamlines, velocity profiles and average Nusselt number variations. The results show that higher Ra values increase the average Nusselt number while increasing Da enhances it by 65%. Magnetic source inclination greatly affects heat transfer, with Nusselt at γ = 90° being 15.34 compared to 10.234 at γ = 0°. The study concludes that optimal heat transfer occurs at γ = 90°, Ra = 106, Da = 10−3, Ha = 30 and N = 2. [ABSTRACT FROM AUTHOR]

Enhancing thermal performance and lowering heat loss in energy conversion systems are essential, especially for new and complicated products that make this requirement worse. In order to address this difficulty, this study looks at fluid flow and heat transmission using hybrid nanofluid and nanoporous materials in combination cavities. The numerical simulation of natural convection within a hollow two-dimensional cavity comprised of two connected tilted squares with a circular hollow at the center is investigated. The inner heated square is filled with a nanoporous material, whereas the rest of the cavity is filled with Cu-Al2O3 hybrid nanofluid. The COMSOL Multiphysics software is utilized to simulate the dimensionless governing equations. A comparison with previously published research showed a good agreement. Calculations are performed for different values of Ra number (Ra: 103, 104, 105, and 106), Darcy number (Da: 10–1, 10–2, 10–3, 10–4, and 10–5), volume fraction (φ: 0, 0.02, 0.04, and 0.06), width (W: 0, 0.1, 0.2, 0.3, and 0.4), and uniform porosity (ε: 0.2, 0.4, 0.6, and 0.8). The results demonstrated that the increase of the porosity leads to a decrease in the Nu number with the Rayleigh number increase. Darcy and Rayleigh numbers have a significant impact on the width (W) between the hybrid nanofluid and nanoporous layers. In addition to the above, the fluid flow slows down at Ra = 103, which causes S ˙ gen , T ⌣ and Be to increase. The rising of Ra from 104 to 105 causes no change in the S ˙ gen , T ⌣ because heat is primarily transported by conduction, but the maximum Be number is reduced. [ABSTRACT FROM AUTHOR]

To overcome the weak thermal conduction of the phase change materials (PCM), This investigation aims to study the effect of circular Y-shaped fins added to a two-pipe latent heat-saving unit compared with conventional circular fins. The system is placed in a straight-up orientation, and the PCM is located in the annulus, whereas hot water is moved inside the internal tube to charge the phase change material (PCM) with a phase change point of 35°C. Different independent geometric factors of the fins involving the length of the stem and angle of the tributaries to the horizontal line and the number of Y-shaped fins are analysed. The impact of the working fluid's Reynolds number and temperature (as the input parameters) are evaluated as a sensitivity analysis to control the output (melting time and rate). The results show that increasing the height and number of the fins and reducing the angles of the tributaries results in higher performance of the system. For the optimal case, increasing the Reynolds number of the working fluid from 500 to 2000 results in 31% reductions in the melting time. Moreover, raising the working fluid's temperature from 45° to 55° reduces the melting time by ~44%. [ABSTRACT FROM AUTHOR]

Convective flowing and heat transference of non-Newtonian liquid comprising nano-encapsulated phase-changing material (NEPCM) suspensions, filled in a square cavity, is numerically investigated. The molecules of NEPCM are cored with n-octadecane, shelled by polymethyl-methacrylate, and suspended in non-Newtonian fluid. The enclosure is insulated horizontally and heated vertically. Finite element method (FEM) is implemented for the numerical solution under different variables such as nanoparticles volume fraction (0 < ∅ < 0. 0 5), Stefan number (Ste = 0. 2 , 0. 3 1 3 , 0. 5), the heat capacity ratio (λ) of about (0.4), the temperature of fusion of the NEPCM (0 < θ f < 1) and the density ratio ( ρ P ∕ ρ f ) (0. 7 < ρ P ∕ ρ f ≤ 0. 9). The results show that the Nusselt quantity is related to the fusion temperature. An improvement in heat transference is observed when the fusion temperature deviates from the wall temperature, which is in the range of 0. 2 5 < θ f < 0. 7 5. For all power law index values (n), a linear increase of the Nusselt number with the solid volume fraction is detected. The shear-thinning nanofluid (n = 0. 6) demonstrates higher Nusselt number values than those of n = 1 and 1.4. [ABSTRACT FROM AUTHOR]

This study aims to enhance the CZTS device's overall efficiency, the key research area has been identified in this study is to explore the effects of a novel, low-cost, and simplified, deposition method to improve the optoelectronic properties of the buffer layer in the fabrication of CZTS thin film solar cells. Herein, an effective way of addressing this challenge is through adjusting the absorbers' structure by the concept of doping, sensitized CdS thin film by the bi-functional linker, and an environmentally friendly catalytic green agent. The Linker Assisted and Chemical Bath Deposition (LA-CBD) method was introduced as an innovative and effective hybrid sensitization approach. In the one-step synthesis process, Salvia dye, Ag, and 3-Mercaptopropionic acid (MPA) were used. Generally, the results for all samples displayed varying bandgap as achieved between (2.21–2.46) eV, hexagonal structure with considerably decreased strain level, broader grain size, and dramatically enhanced crystalline property. Hence, the rudimentary CdS/CZTS solar cell devices were fabricated for the application of these novel CdS films. Preliminary CZTS thin film solar cell fabrication results in the highest conversion efficiency of 0.266% obtained CdS + Salvia dye, indicating the potential use of the CdS films as a buffer layer for CZTS photovoltaic devices. [ABSTRACT FROM AUTHOR]