Itimad Dj Azzawi

Solar air collectors have been used in a variety of industrial applications, prompting a study and summary of various studies on the topic. Solar collectors’ exceptional energy conversion and storage outputs have piqued curiosity in the field of energy research. The current review study focuses on solar thermal application advancements and provides an overview of thermal energy storage devices and solar collectors. This paper presents and discusses a variety of solar collectors, both concentrating and non-concentrating. The energy storage media utilized in these plants, phase change material with melting temperatures exceeding 300°C, was exam-ined. The goal of this study is to provide the necessary information for advanced investiga-tions in the development of cost-effective high-temperature thermal storage systems. Finally, a summary of the presentation, as well as potential solar power plants are reviewed.

Free convection is widely used in engineering applications, including solar energy, electronic devices, nuclear energy, and heat exchangers. A computational simulation utilizing Ansys Fluent-CFD was employed to examine the natural convection heat transfer inside a square cavity filled with pure water and saturated metal foam as a porous medium (porosity ɛ =0.9). The enclosure's lower wavy wall exhibits a high temperature (T_h), while the side and upper walls have a low temperature (T_c). For different Rayleigh numbers, the study examines hump configuration and the bottom wall hump number (N). The predominant design of heat transmission was improved using the circular hump design parameters of ɛ=0.9, N=4 and T_c= 25C˚ for different Ra. This resulted in significant improvements in heat transfer enhancement and energy enhancement which were enhanced by 1.13 times, for both. The authenticity research included determining the optimal design for the square enclosure. This involved estimating the effects of hump configure and number of humps for bottom wall of enclosure. These parameters have not been studied yet. The optimum case showed the highest heat transfer coefficient (h) at circular hump, N=4 and Ra = 30´10³. While the standard case had N=0 and Ra = 5´10³. The CFD simulation results indicate that the primary objective of the study was achieved through the optimal design, which resulted in a significant enhancement of hydrothermal performance for both heat transfer enhancement and energy enhancement 1.13 times compared to standard case.

A new subsonic blower wind tunnel design has been studied both numerically and experimentally; it is also referred to as “blower” wind tunnel. This paper is initially aimed to address each sequential stage of the wind tunnel design process. Rather than applying the standard method of modelling solely the flow in the test section, a large-scale CFD model of the whole wind tunnel was employed. The loss of every constituent element was calculated and then all the losses are added up to determine the power needed for the wind tunnel operation which is used as “intake fan” boundary conditions in the CFD model. Then, flow uniformity and turbulent intensity measurements in an empty test section using a pitot static tube and hot wire anemometer (HWA) were introduced to validate the CFD results. The results showed that flow quality was significantly affected by flow conditioners (uniformity devices) (honeycomb and mesh screens) in the settling chamber and wide-angle diffuser. Investigations were also conducted to evaluate the flow deficit in the wake area behind a convex hump model using both HWA and particle image velocimetry PIV. This was additional experimental tests carried out to validate the suitability of the wind tunnel designed for aerodynamic research.

This paper provides an in-depth review of the current state and future potential of hydrogen fuel cell vehicles (HFCVs). The urgency for more eco-friendly and efficient alternatives to fossil-fuel-powered vehicles underlines the necessity of HFCVs, which utilize hydrogen gas to power an onboard electric motor, producing only water vapor and heat. Despite their impressive energy efficiency ratio (EER), higher power-to-weight ratio, and substantial emissions reduction potential, the widespread implementation of HFCVs is presently hindered by several technical and infrastructural challenges. These include high manufacturing costs, the relatively low energy density of hydrogen, safety concerns, fuel cell durability issues, insufficient hydrogen refueling infrastructure, and the complexities of hydrogen storage and transportation. Nevertheless, technological advancements and potential policy interventions offer promising prospects for HFCVs, suggesting they could become a vital component of sustainable transportation in the future.

The application of natural convection heat transfer within a novel Ϻ-shaped cabinet filled with single-phase pure water/metal foam is investigated numerically. Natural convection is modeled throughout the porous zone using the Local-Thermal-Equilibrium mode and Darcy-Forchheimer-Brinkman law. A novel Ϻ-shaped cabinet with varies Ϻ ratio (0 ≤ Ϻ ≤ 0.8) and temperature difference (10 K ≤ ΔT ≤ 40 K) is applied at a constant porosity of ε = 0.85. Furthermore, the current research is conducted to analyze the response surface methodology (RSM) accompanied by a computational simulation for optimizing the multi-objective function of the M-shaped cabinet in terms of two computed responses: maximizing the Nusselt number ratio (NNR) and minimizing the entropy generation ratio (EGR). The optimization study considers the various pore per inch (10 ≤ PPI ≤ 50), Darcy number (10-9 ≤ Da ≤ 10-1) and uniform magnetic fields (0 ≤ Ha ≤ 100). The results showed that the optimum working conditions consistent with the desired aim are achieved in the maximization of NNR by nearly 26.84 times and the minimization of EGR of 0.895 obtained at Ha = 100, Da = 10-¹ and PPI = 30. Thus, the current investigation is a unique application study of CFD and RSM which provides a helpful reference for the optimum design cooling efficiency and entropy performance of a novel Ϻ-shaped cabinet.

Thermoacoustic refrigeration systems are one of the best alternative solutions for conventional refrigeration systems that are harmful to the environment and humans due to global warming and ozone layer depletion issues. Thermoacoustic technology can be considered a renewable and clean technology with a promising future for its many advantages. A thermoacoustic refrigerator converts acoustic energy to thermal energy (creating a cooling effect). In the present research, the focus is on the design of a standing-wave thermoacoustic refrigerator driven by an ordinary loudspeaker using the numerical simulation program DELTAEC with the concern of building the apparatus at a low cost. In addition, investigating the influence of some crucial parameters on cooling power and thermal/overall performance. Hence, the designed thermoacoustic refrigerator performed well in respect of cooling power and coefficient of performance. It has achieved a cooling power of 134.34 W with a temperature difference between the ambient and cold heat exchangers of 25 K at a COP of 1.956 and the overall efficiency (electrical power converted into cooling power) amounted to 113.43%. The achieved cooling power and COP could be significant when compared to others’ results.

The current research employed computational simulation to assess magnetohydrodynamic (MHD) natural convection in an L-shaped container with a metal foam, which has a variety of engineering applications. The originality of this study is the use of numerical simulation combined with multi-objective optimization in terms of cooling rate enhancement and entropy generation reduction to investigate the optimal natural convection regimes. The influence of varied aspect ratios (AR), tilted angles of the container (θ), Hartmann number (Ha), and porosities (Φ) on the cooling rate with regard to the average Nusselt number (Nuave), Nusselt number enhancement (NNE), dimensionless surface temperature ([Ts]) and entropy generation (S) were evaluated. According to the findings of this study, little effect was found to be exerted by the MHD and θ on the Nuave, Ts, and S except for a porosity of 0.9. Furthermore, the Nuave and NNE enhance while the Ts and S reduce as the aspect ratio AR increases. In this case, the maximum increase in NNE was 8.78 times, with the greatest reductions in Ts and S as AR = 0.8, Φ = 0.1, θ = 0 deg, and Ha = 0 compared to the least favorable design. Thus, this optimum investigation of the CFD yields a novel approach and valuable recommendations for the optimum design of cooling in an L-shaped container.

To quantify the benefits of reducing entropy production and improving hydrothermal performance with varied thermal air characteristics through different perforated heat sinks, a numerical study was conducted. Various numbers of circular perforations are studied from 0 perforations to 5 perforations. In addition, perforation configuration is considered, such as circular (3CP), square (3SP), elliptic (3EP), and triangular (3TP) perforated pinned heat sinks, as well as three slotted pinned heat sinks (SPHSs) (3S, 6S, and 10S) and four notched pinned heat sinks (NPHSs) (3S, 6S, and 10S) (2.5 N, 5 N, 7.5 N, and 10 N). The numerical results showed that the 5-circular perforations heat sink model (5CP) generates the minimum entropy generation and the maximum hydrothermal performance (HTP), around 17% and 1.2, respectively compared to the zero-perforation model, while the circular perforated pinned heat sink (3CP) model produces the maximum reduction in entropy generation, generally around 13% with moderated HTP of 1.1. Moreover, when comparing slotted and notched pinned heat sinks, the 10S slotted and 10 N notched pinned heat sinks achieve 1.45 of HTP.