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The current paper reports the impact of variation of ribs' pitch distance in the case of laminar flow and forced convection heat transfer upon flow characteristics in a rectangular channel experimentally and numerically. The thermal behavior of the ribbed channel with water as a working fluid was measured experimentally and compared to numerical simulations performed using Galerkin finite element method under the same operating and boundary conditions. Numerical analysis has been extended to investigate the entire ribbed channel with the presence of nano-particles in the base fluid to predict the performance of the heat transfer process with interaction with extended geometries. The analysis was done keeping heat flux constant at the bottom boundary condition. The impacts of the rib pitch-to-height ratio (p/e = 2.5, 3.125, 3.75, 4.375, and 5), nano-particle volume concentration (0% ≤ φ ≤ 4%), also Reynolds numbers (427.44 to 1282. 9), were all examined in the present study. The results show a good coincidence between the numerical and experimental study with a maximum deviation was nearly 3%. The main findings show that when the nano-fluid volume fraction increases from 0% to 4%, the average Nusselt number for all aspect ratios increases too. Meanwhile, the average skin friction decreases as the Reynolds number increase for different values of AR. Furthermore, the results revealed that the water – aluminum oxide nano-fluid with the concentration φ = 0.04 aid to improve the coefficient of heat transfer by 5% higher than the case of φ = 0.02, and up to 9.4% compared to pure water (φ = 0) due to an increase in viscosity. Finally, the current work shows that these extended surfaces with the use of nano-fluids can remarkably improve heat transfer properties with barely increased friction, making them suitable candidates for the development of efficient heat exchanger devices. [ABSTRACT FROM AUTHOR]

The physical properties of working fluids—in terms of the Prandtl number—play a crucial role in determining their thermal performance in the internal flow, especially their viscosity. This study first considers the thermo-hydraulic and entropy generation of a sinusoidal corrugated channel in two configurations: symmetrical (raccoon) and asymmetrical (serpentine). Results are presented for different ranges of operating parameters, such as 100 ≤ R e ≤ 700 and 0.72 ≤ P r ≤ 90 , and for geometrical parameters such as the wave amplitude-to-wavelength ratio 0.2 ≤ α ≤ 0.6. In addition, the results of the two channels were compared with each other's and with the straight channel. Control transport equations are solved using finite element methods. It was found that the flow inside the wavy channels generated re-circulatory reigns, and their size was affected by the wave parameters as well as the Reynolds number. Also, employing high values of P r extremely enhanced the heat transfer rate (HTR) of the wavy channels over the straight for all values of α and for both raccoon and serpentine channels. In addition, the results indicated that raccoon channels have higher HTR and performance factor compared to the serpentine channel. Finally, the thermal entropy generation dominated over the viscous entropy generation and its decrease with both Reynolds number and Prandtl number for raccoon and serpentine channels. This study focused on the heat transfer enhancement of the corrugated channels due to their importance in many industrial applications where the heat dissipation is critical to their work, including heat exchangers and heat sinks. Thus, the current numerical simulation primarily suggests utilizing the raccoon channel over the serpentine one, due to its higher thermal performance and nearly the same total entropy generation. [ABSTRACT FROM AUTHOR]

Previous works that investigated the characteristics of heat transfer and fluid flow in channels with corrugated walls have been extensively reviewed in this study. In accordance with the fast increase in power consumption requirements, many researchers have investigated a new approach for cooling techniques that can enhance the cooling performance of devices without consuming more power. To improve the efficiency of energy systems, many investigators and engineers implement promising techniques such as surface optimization and additives as passive methods to augment the rates of heat transfer. Researchers investigated different corrugation profiles along with various working fluids as well as external power devices to further improve the heat exchange process of thermal systems. The aim of this article is to give a clear preview of the effects of different parameters such as wave parameters, Reynolds number, type of working fluid, and pulsating flow condition on the average and local Nusselt number, the pressure drop, the performance factors, and irreversibility. The main findings are listed in tables and depicted in figures, the matter that helps engineers and researchers to choose a suitable channel shape for their applications. [ABSTRACT FROM AUTHOR]

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]

This correction notice addresses an error in a previously published article titled "Sugarcane Biomass as a Source of Biofuel for Internal Combustion Engines (Ethanol and Acetone-Butanol-Ethanol): A Review of Economic Challenges." The original article included an incorrect reference, which has now been replaced with the intended reference. The correction specifically relates to the section on economic challenges in biofuel production from sugarcane waste. The authors state that this correction does not affect the scientific conclusions of the article. [Extracted from the article]

Great attention is directed towards the study of the spray phenomenon theoretically and experimentally due to its dramatic effect on the combustion process that occurred in an internal combustion engine, in particular, the diesel engine. The spray macroscopic characteristic of diesel engines fueled with two different biodiesel fuels in addition to nominal diesel under various injection pressures has been investigated numerically in this work. The selected biofuels are rapeseed methyl ester (RME) and waste cooking oil methyl ester (WCOME). The Russian simulation software Diesel-RK is used in this work. Four different injection pressures are used, which are 200, 500, 800, and 1000 bar, respectively. It is found that RME has higher spray penetration with a narrow spray angle due to high viscosity and large momentum compared to diesel fuel. The results reported that biodiesels have greater Sauter mean diameter (SMD) compared to pure diesel because of their higher viscosity and surface tension. Promising reduction in SMD comes with WCOME as the injection pressure increases. Cylinder pressure along with heat release is reduced in the case of biodiesel due to the reduction in heating values. The lowest ability to produce smoke is recorded for WCOME, where 93% reduction is achieved followed by a 57% reduction for RME as compared to diesel. The obtained results are compared with the results of other researchers, and the convergence between them is observed. [ABSTRACT FROM AUTHOR]

The present work numerically demonstrates the uniform magnetohydrodynamics Newtonian, laminar natural convection in elliptical cold enclosure with inner hot circular body considering the influence of its vertical movement on the fluid flow and heat transfer. The gap area between the elliptical enclosure and the inner body had been filled by the Al2O3-water nanofluid in the upper layer, whereas lower layer has been filled by the porous medium that has been saturated by an identical nanofluid. The local thermal equilibrium model had been implemented to model the nanofluid and porous media. Additionally, Darcy–Brinkman model considered in the representation of the porous media. The three governing equations of heat and fluid flow like energy and momentum of fluid, in addition to the continuity equation, had been solved numerically utilising finite element formulation. The parameters under investigation are the Rayleigh number value $\left({{{10}^3} \le Ra \le {{10}^6}} \right)$103≤Ra≤106, Darcy number $\left({{{10}^{ - 5}} \le Da \le {{10}^{ - 1}}} \right)$10−5≤Da≤10−1, and Hartmann number $\left({0 \le Ha \le 60} \right)$0≤Ha≤60. Additionally, two geometrical parameters had been selected, which are the three different locations of inner cylinder (top, middle, bottom), as well as the four different values of the enclosure’s orientation angle $\left({\gamma = 0^\circ ,\gamma = 90^\circ ,\gamma = 180^\circ ,\gamma = 270^\circ } \right)$γ=0∘,γ=90∘,γ=180∘,γ=270∘. The results have been presented to reflect the influence of the abovementioned parameters on isotherms and streamlines, besides Nusselt’s number. It has been proved that to improve the heat transfer rate, it is better to locate inner body in bottom region. The Nusselt number increases by 17.44% when it is moved from the top to the bottom. Additionally, the Nusselt number along the elliptical enclosure attached to the nanofluid layer when rotating the elliptical body from $\left({\gamma = 0^\circ } \right)$γ=0∘ into $\left({\gamma = 180^\circ } \right)$γ=180∘ leads to lower the Nusselt number by 32.3372%. This result is exactly inverse considering Nusselt number along nanofluid–porous layer which proved that increasing the orientation angle from $\left({\gamma = 0^\circ } \right)$γ=0∘ to $\left({\gamma = 180^\circ } \right)$γ=180∘ contributed to enhancing Nusselt number by 24.7009%. [ABSTRACT FROM AUTHOR]