Arabian Journal for Science and Engineering最新文献

In recent years, the demand for LED lighting utilizing power electronic converters has increased markedly. In lighting applications, it is essential to engineer power converters capable of efficiently managing both single and multiple loads. LEDs have greater sensitivity to variations in input voltage, current, and conversion parameters compared to other illumination sources. This article presents a comparative examination of different isolated power converter topologies for LED applications, emphasizing critical characteristics such as power density, load-handling capacity, volume, and reliability. The comparison also evaluates power rating, number of switches, switching frequency, and efficiency, providing an impartial and fair assessment. Furthermore, we examine diverse dimming control methodologies that produce varying light intensities. This study dissects and analyzes the key properties of LED drivers to assist researchers in selecting the most appropriate converter for various lighting applications. This research will be especially pertinent to scholars engaged in the advancement of LED drivers.

Climate change poses a severe threat to both the environment and human health, manifesting in floods, droughts, global warming, and food and energy security threats. This threat arises from the emission of greenhouse gases (GHGs), especially carbon dioxide (CO₂). The challenge lies in effectively managing and utilizing CO₂ by reducing atmospheric carbon footprints and integrating CO₂ into the energy value chain in the Middle East and North Africa (MENA) region, where the prominent oil and gas industry and the transition to renewable energy sources are emerging. Thus, understanding the progress in carbon management is crucial. The carboniferous geological formations in this region present promising prospects for CO₂ storage, emphasizing the permanence of sequestration and the potential for enhancing oil recovery and economic diversification. This review systematically examines the carbon capture, utilization, and storage (CCUS) life cycle, including CO₂ emissions, CCUS technologies, research and development (R&D) trends, and policy frameworks in the MENA region. Furthermore, it discusses the main challenges in implementing CCUS projects in a larger scale in this region. The modularized approach of this analysis is motivated by the absence of a comprehensive review for this region. It aims to provide strategic insights into the region’s global standing in the rapid growth of environmental responsibility.

Nuclear reactor power for a heat to desalinate the seawater has been deeply considered in Saudi Arabia. For this purpose, the steam temperature shall be required with the relative low temperature around (100,^{circ }hbox {C}). The 400MWth nuclear heating reactor (NDP-400) dedicated to supplying heat for desalination is developed with cooperation of Saudi Arabia and South Korea. In order to improve the safety and to achieve the economics goal, the advanced features, in-vessel control rod drive mechanism (IV-CRDM), printed circuit heat intermediate exchanger (PCIHX), and canned motor type reactor coolant pump (RCP) are harmonized with the design of SMART, which is an integral-type SMR developed by KAERI. This paper will describe the main design features and safety analysis results for representative accidents for the NDP-400

A wide range of technical applications, including solar power, waste heat recovery, electronics thermal management, and heat exchangers, employ thermoelectric generators. They can be mounted in between channels / cavities where hot and cold fluid streams exist. In this study, two novel methods of enhancing the power generation from thermoelectric generator device mounted in between vented cavities are proposed by combined utilization of active heater/cooler rectangular blocks and blade-shaped nanoparticles in base fluid. Finite element method investigation is conducted numerically for a range of hot and cold stream Reynolds numbers (250–1000), non-dimensional hot and cold block sizes (0.01(-)0.4), and heating/cooling increments (0–10), with nanoparticle loading limited to 0.03. Higher values of Reynolds number results in a rise in thermoelectric generator power. When comparing the cases of lowest and highest Reynolds number combinations, a 219(%) increase in power is achieved. The thermoelectric generator power will rise by around 27.5(%) when the object size reaches its maximum. However, for moderate object sizes, up to 31.6(%) reduction in power generation can be realized. Greater temperature differences result in a linearly rising power generation, with an achievable power increase of up to 22(%). When nanoparticle loading in the base fluid for both cavities is raised to its maximum value, the resultant power increases by around (30%). Thermoelectric generator power rises by 67.8(%) when an active heater/cooler with nanofluid is used in vented cavities, as opposed to the reference scenario of employing no object and only water. The thermoelectric generator device’s hot and cold interface temperatures are accurately estimated using the artificial neural network based method. The estimated temperature can be used as boundary condition for the solution of the governing equations in the thermoelectric generator device domain which will decrease the computational cost when dealing with very complex channel configurations.

Lignocellulosic biomass (LCB) is a promising renewable energy source. However, its efficient utilization, extraction of different fractions like cellulose, hemicellulose and lignin, and conversion to value-added products require pretreatment to break down its complex structure. This review explores various conventional and green pretreatment techniques for LCB fractionation into cellulose, hemicellulose and lignin. Besides, comparative analysis evaluates the merits/demerits of each method based on the treatment conditions and yield of the extracted fractions. It emphasizes on the importance of developing efficient, eco-friendly and cost-effective green pretreatment techniques to enhance the utilization of LCB for extracting its constituents and creating valuable products. Finally, the review explores the emerging role of machine learning-assisted pretreatment processes for optimizing process efficiency and product yield by appropriate model selection. It also discusses the application of these extracted fractions in various industries such as oil/water separation, effluent processing and electrochemistry especially in electrodes.

Rapidly increasing global atmospheric carbon dioxide (CO₂) concentrations, a direct consequence of unabated fossil fuel combustion, pose a serious threat to our planet, fueling drastic global climate change. In the last ten years, there has been a surge in the development of chemical sorbents cycled through adsorption–desorption processes for CO₂ uptake, usually from low-concentration stationary sources like atmospheric air. The efficiency of these technologies, however, will depend on the development and optimization of promising next-generation materials tailored specifically for CO₂ capture. Graphene, a special distinctive material discovered about two decades ago, has the potential to propel the world even further toward a more sustainable future goal, for our largely fossil fuel-dependent economies. Graphene has a single-atom-thick sheet of sp²-hybridized carbon atoms causing it to have exceptional and tuneable properties. These have made graphene the most widely studied nanomaterial of the twenty first century. This review provides a comprehensive overview of the graphene-based materials for CO₂ capture/conversion. The review commences by exploring the synthesis techniques for graphene and the addition of dopants to tune its properties for targeted CO₂ capture applications. Furthermore, the review discusses graphene derivatives for CO₂ capture applications. Despite the immense potential, the practical implementation of graphene-based materials for direct air capture (DAC) will further exploration and development. Notably, engineering efficient graphene-air interfacial contact is paramount to expediting the deployment of DAC as a viable strategy for mitigating climate change. The review concludes by charting avenues for future research in environmental pollution mitigation through advanced material science and engineering approaches.

In a world grappling with heightened carbon levels, the imperative for mankind to coordinate efforts toward a carbon-reduced future has reached a critical juncture. Against this backdrop of ecological urgency, the emergence of renewable energy harmonizes as a crucial note, promising a melodic progression in the collective journey toward sustainability, decarbonization, and climate change mitigation. This comprehensive review navigates through the literature, offering a panoramic exploration of the historical, contemporary, and prospective landscapes of renewable energy sources. It delves into their merits, drawbacks, research gaps, and various storage and transmission methods. The study deeply compares the efficiency of renewable sources, considering factors such as the levelized cost of electricity, capacity factor, and installation costs. Additionally, it highlights the practical applications of renewables through insightful case studies. The central focus is on assessing the status of renewables in the energy mix, elucidating its holistic capacity amidst rising energy demands, and examining prevailing policies, research investments, and the contributions of oil companies to the renewable industry. The review envisions renewables claiming a larger share in electricity generation than fossils, but recommends alliances with hydrogen energy and carbon capture, utilization, and storage for a low-carbon future. It stresses continuous advancements in renewable technologies and enhancing efficiency, reliability, and scalability to accelerate the transition to sustainability.

Slickwater, a low viscosity fracturing fluid, is prevalent in the stimulation of hydraulic fracturing operations due to its efficacy in penetrating tight formations and providing the necessary fracture conductivity. However, its proppant-suspending capabilities, which are crucial for transporting proppants to the intended locations within induced fractures, pose a significant challenge. A comprehensive understanding of proppant transport behavior during fracturing is essential for successfully creating the desired geometry of fractures that are kept open by the proppants, thereby enhancing the productivity of the well. This paper offers a comprehensive review of the intricacies of proppant transport in slickwater-based fracturing treatments, drawing upon experimental data, numerical simulations, and analytical models. It delves into the multifaceted interactions between slickwater and proppants, exploring the impact of factors like injection rate, proppant size and concentration, fluid viscosity, and fracture complexity on the effectiveness of hydraulic fracturing treatments. Through a synthesis of existing knowledge and the identification of future research directions, this paper seeks to refine proppant distribution strategies, addressing the constraints of slickwater use and promoting sustainable, efficient resource extraction in the continually advancing field of hydraulic fracturing. Additionally, it aims to optimize fracturing treatments by mitigating slickwater's limitations, thereby ensuring improved fracture treatment outcomes.

Thermoelectric applications have sparked significant interest in organic–inorganic hybrid composites. In this research, the optimal experimental parameters of a p-n (polypyrrole–titanium oxide) thermoelectric formulation material are identified using the response surface technique (RSM), which is based on the central composite model (CCD). The relationship between the three investigated parameters, including electrical conductivity (σ), thermal conductivity (κ) and Seebeck coefficient (S), was modelled by a polynomial equation of the second order. Then, the titanium dioxide spherical particles are given a nanotube structuring process, which results in an even better composite. Additionally, 1D model ternary hybrid composite based on the inclusion of carbon nanotubes was made, resulting in an improvement of three-order magnitude of the merit coefficient ZT = 9.69 × 10^–4. Transmission electron microscopy (TEM) evaluation revealed the successful of the CNT/PPy nanocomposites external walls decoration through an intimate contact with the formed TiO₂ nanotubes.