The high heat dissipation of high-power electronic equipment has become a major cause of damage, especially the central processing units (CPUs) of computers and other electronic devices. Accordingly, this research aims to improve the thermal conductivity as well as the mechanical properties of aluminum (Al) by mono and hybrid reinforcements of silver (Ag) and graphene (G) so that they can be used for heat dissipation. The structures of the prepared powders were investigated using the X-ray diffraction (XRD) technique. Furthermore, the sintered composites’ microstructure, density, thermal conductivity, mechanical properties, and electrical conductivity were investigated. The results showed that adding Ag percentages led to forming the Ag₂Al phase while adding graphene decreased the crystallite of the milled powder. The SEM results showed that the samples had high densification, which was slightly reduced with increasing percentages of reinforcements. Importantly, Al’s thermal conductivity and mechanical properties were significantly improved due to the addition of Ag and G reinforcements with a slight decrease in electrical conductivity. The highest thermal conductivity was observed a 278.86 W/mK in the sample containing 5 vol.% of Ag and 2.5 vol.% of G, which was improved by about 20.6%. In contrast, the highest microhardness and Young’s modulus were 39.19 HV and 71.67 GPa, which resulted in an improvement of about 30.7 and 17.8% for the sample containing 2.5 vol.% of Ag and 5 vol.% of G when compared to the Al matrix. Based on these promising findings, it is possible to infer that the objective of this study was effectively attained and that the created composites are appropriate for such applications.

Flow over shallow cavities is used to model the flow field and heat transfer in a solar collector and a variety of engineering applications. Many studies have been conducted to demonstrate the effect of cavity aspect ratio (AR), but very few studies have been carried out to investigate the effect of cavity height ratio (HR) on shallow cavity flow behavior. In this paper, flow field structure and heat transfer within the 3-D shallow cavity are obtained numerically for two height ratio categories: HR = 0.0, 0.25, 0.5, 0.75, and 1.0 and HR = 1.25, 1.5, 1.75, 2.0, 2.25, and 2.5. The governing equations, continuity, momentum, and energy are solved numerically and using the standard (K-ε) turbulence model. ANSYS FLUENT 14 CFD code is used to perform the numerical simulation based on the finite volume method. In this study, the cavity aspect ratio, AR = 5.0, and Reynolds number, Re = 3 × 10⁵, parameters are fixed. The cavity’s bottom wall is heated with a constant and uniform heat flux (q = 740 W/m²), while the other walls are assumed to be adiabatic. For the current Reynolds number and cavity geometry, a single vortex structure (recirculation region) is formed and occupies most of the cavity volume. The shape and location of the vortex differ according to the height ratio. A reverse velocity profile across the recirculation region near the cavity’s bottom wall is shown at all cavity height ratios. Streamlines and temperature contours on the plane of symmetry and cavity bottom wall are displayed. Local static pressure coefficient and Nusselt number profiles are obtained along the cavity’s bottom wall, and the average Nusselt number for various height ratios is established. The cavity height ratio (HR) is an important geometry parameter in shallow cavities, and it plays a significant role in the cavity flow behavior and heat transfer characteristics. The results indicate interesting flow dynamics based on height ratio (HR), which includes a minimal value in average Nusselt number for HR ≈ 1.75 and spatial transitions in local Nusselt number distribution along the bottom wall for different HRs.

In combined cycle gas turbines, most of the energy loss is usually due to the high temperature of the exhaust gases. Different heat recuperation methods are used. In this study, a novel direct method for heat recovery is investigated. Confidence in the results is established by accounting for all the losses and simulation errors while comparing with the conventional cycle. Aspen HYSYS and MATLAB are the simulation tools used. The General Electric (GE) 9HA.02 combined cycle is taken as a base case. Five gases, air, argon, hydrogen, nitrogen, and carbon dioxide, are studied with the proposed modification. The efficiency maximization function is updated and the pressure and temperature ratios of individual Brayton and Rankine cycles are discussed. The combustor/heat exchanger is modified and simulated according to the known principles of heat and momentum transfer. The whole simulation algorithm is provided. Equation of state (EOS-PR) is used to calculate the properties at every discretized step (for H₂, critical properties are modified/HYSYS inbuilt feature). Different gases are analyzed according to their property profiles over the whole cycle. The effect of fluid properties on efficiency is discussed as a guideline for any tailored fluid.

A wind tunnel is needed for a lot of research and model testing in the field of engineering design. Commercial wind tunnels are large and expensive, making them unsuitable for small-scale aerodynamic model testing. This work aims to experimentally investigate the effects of flow, noise, and vibration on constructing and designing a low-speed wind tunnel structure. The flow uniformity in the wind tunnel has been tested by measuring the velocity profiles inside the empty test section with a pitot-static tube at various fan frequencies. The experiment results showed a good flow uniformity of more than 90% across the test section area, and the maximum wind velocity achieved was about 25.1 m/s. Due to the stability of the flow near the exit test section, the vibration measurement revealed that the entrance portion has larger vibration fluctuations than the exit part. Furthermore, as the axial fan frequency increases, the noise level increases. At 40 Hz, the noise level enters the hazardous zone, which has an impact on the person who performs the measurement process. The resonance of the wind tunnel structure is an important measurement test that affects vibration measurement.

A study of vehicle exhaust dispersion within different street canyons models in anurban ventilated by cross-wind is conducted at this work to investigate how pollutiondispersion is affected by wind speed, building height to width ratios, street and buildinggeometries, and canyon street number. For all cases, cars exhaust was represented by a linesource emitting CO2 and pollution dispersion was studied in two and three dimensions,airflow and the street canyons were assumed thermally isolated. The FLUENT ComputationalFluid Dynamics (CFD) software package has been used with a standard k-ε, RNG k-ε andsstk-ω turbulence models to simulate different street canyon models. For all models, theresults show a vortex appearance within the street canyon, with updrafts near the upwindbuildings and down-draft near the downwind buildings. In the transverse vertical plane atmid-canyon show that the pollutant concentrations has higher concentrations at the leewardface than that at the windward faces, and has higher concentrations above downwindbuildings than that above upwind buildings, Longitudinal distributions of pollutantconcentrations at leeward and windward faces show decreasing of the concentration withincreasing building height. For multi-street models, the pollutant concentrations increase forhigher order street in wind direction. The pollutant concentration results were compared withMeroney et al. [9] experiments. Also a series of flow visualization and static pressurecoefficient measurements were performed in the smoke tunnel and wind tunnel to comparedwith the numerical study.