Iraqi journal of mechanical and material engineering

Corrosion is a major challenge in all industrial sectors, prompting the scientific community to search for effective solutions that can stop or reduce corrosion attacks. Inhibitors (both synthetic and natural) have emerged as the ideal solution to this challenge. In this context, nano silica has been found to be a promising material due to its unique environmentally friendly properties and high surface area, capable of forming interconnected protective layers. In this study, nano silica was prepared from Najaf sand, Iraq, using the sol-gel technique, which allows precise control of particle size and porous structure. Tests were conducted to characterize the distinctive nature of nano silica. FTIR analysis revealed the presence of effective functional groups such as Si-O-Si. The chemical composition of the silica sample was examined. The results showed that the silica extracted from Najaf sand has high purity (up to 96%), enabling it to achieve high energy efficiency based on the strength of its bonds under hostile conditions, as measured by XRD. This outstanding performance is attributed to the nanoparticles' ability to diffuse effectively, as measured by surface morphology (SEM). The research confirmed the synergistic role of nanotechnology in enhancing the effectiveness of silica, as the ultrafine particles contributed to improving selective interactions with corrosive agents. The study concluded that nano-silica prepared from Najaf sand is a highly efficient and low-cost corrosion inhibitor, supported by the abundance of local raw materials. The study recommends the use of silicate inhibitors in the oil and infrastructure industries, with further research being conducted to exploit their effectiveness under various operating conditions, which will contribute to reducing economic losses and establishing principles of environmental sustainability.

This research focuses on studying gas-liquid flow phenomena in engineering applications by de-signing and developing an advanced electromagnetic sensing system utilizing microwave technology. The objective is to analyze multi-phase flow characteristics and determine volume fractions within the oil and gas industry. A horizontal pipe model was used, featuring a non-intrusive cylindrical sensor, with LabVIEW software which has been employed for real-time data acquisition, processing, and visualization of results. Additionally, to analyze the electromagnetic behavior of the multiphase flow, Experimental measurements were conducted that the electromagnetic reflection coefficient S22 is strongly correlated with changes in the fuel (oil) ratio inside the pipe, particularly within the frequency range of 2.6 to 3.3 GHz. After validating the results through a simulation study using the HFSS program, it was further observed that increasing the air flow rate caused a significant change in the electromagnetic wave response. Consequently, fluid flow measurement was identified as an alternative to the traditional method. These results demonstrate the system's capability to effectively track flows in various scenarios. Moreover, the direct comparison between the obtained and calculated data showed a similarity of approximately 85%, demonstrating the adequacy of the applied theoretical model in characterizing the mixture flow behavior. This work presents a novel and effective method for determining the oil-to-air ratio, which can enhance electro-sensing approaches in real-world environments.

Due to the difficult conditions in Iraq and the increasing frequency of terrorist attacks, the number of amputees has skyrocketed. However, trans-tibial amputations account for about 80% of all amputations. The creep behavior of composites was investigated using tensile creep testing. In this investigation, fifteen laminated composites were used. The polyester polymer was used as the matrix and strengthened with fibers, including jute, glass, hemp, carbon, and person, which were created by the vacuum molding process. Socket materials were evaluated for their mechanical properties to select a laminated composite that must support loads for prolonged periods. According to the data, the best-laminated samples contained two layers of carbon fiber and three layers of natural fiber. This indicates that the hemp-carbon hybrid with a 0.00031(%/hr.) creep rate is more resistant to creep than natural fiber alone or other hybrids. As the total of fiber layers rises, the creep rate lowers. This investigation concluded that the mechanical assets were affected by the kind and quantity of supporting layers. These results highlight the natural fiber laminate's potential for orthopedic applications with improved biocompatibility.

This study experimentally investigates natural convection heat transfer in an inclined rectangular duct with a square cross-section. The effects of inclination angles (30°, 45°, and 60°) and v-shaped ribs on the performance of heat transfer are examined under steady-state conditions at a heat flux varying from 63.45 W/m² to 634.52 W/m². The modified average Rayleigh number (Ra*) ranges from 11.5×106 to 10.56×107 and a. The results indicate that increasing the inclination angle and adding ribs significantly enhance natural convection by intensifying turbulence and disrupting the thermal boundary layer. With increasing inclination angle and the introduction of V-shaped ribs, at 30o, 45o, and 60o, the ribbed duct showed heat transfer enhancements of 21.7%, 32.17%, and 48.15%, respectively, compared to the smooth duct. Furthermore, the local heat transfer increases with inclination angle and adding ribs.

The purpose of an automobile brake is to absorb the kinetic energy of moving parts through friction. This study investigates the formulation of brake pad material using coir and cow bone reinforced polymer composite. Three different samples were created with varying proportions of coir, cow bone, and polyester resin: S1 (5% coir, 15% cow bone, 80% resin), S2 (5% coir, 10% cow bone, 85% resin), and S3 (5% coir, 5% cow bone, 90% resin). Mechanical tests showed that S3 outperformed the others in hardness (93.90), compressive strength (94.30 N/mm²), and tensile strength (18.82 N/mm²), indicating its potential for excellent braking performance. S3 also demonstrated low water absorption (1.99%), suggesting improved resistance to water-related damage, enhancing brake pad longevity. The wear index for S2 was also favorable (0.0135), indicating its potential for durable performance. Overall, the coir and cow bone reinforced polymer composite, especially the S3 formulation, offers superior mechanical properties compared to traditional brake pad materials. This innovative composite demonstrates great potential for tricycle brake pad applications, offering improved performance, durability, and environmental resistance.

In this study, a two-dimensional numerical method is employed to discretize the governing equations for heat transfer and mixed convection inside a square cavity with a sinusoidal bottom wall. The numerical method is based on the variational formulation/finite element with triangular nonsymmetrical elements. The vertical walls of the cavity are kept at a constant cold temperature, while the constant temperature heat source is applied to the sinusoidal bottom wall. The top wall and the rotating cylinder inside the cavity are considered insulated. The dimensionless angular velocities of an insulated rotating solid cylinder that have been considered are 0, 3000, and 6000 clockwise/counterclockwise. The working fluid is Al2O3 nanofluids with porous media at varying ratios. This analysis examined various ratios of nanofluids/porous media (nanoporous) volumes to the total enclosure volume, ranging from 0% to 100%, with a 25% increment. The effect of nanoporous media volume on the main pertinent parameters (velocity vector, heatlines, isotherms, dimensionless entropy, Bejan number, streamlines, and Nusselt numbers) is investigated at various solid cylinders’ rotational angular velocities. A constant Rayleigh number (104), Darcy number (10-3), and nanopartical solid volume fraction (0.02) are used. The results of the present work have been validated against several published works, to test the accuracy of the present analysis. In the present analysis, the data is plotted for different main parameters. The findings of this work showed that the average Nusselt number values on the hot wall increase as angular velocity increases, regardless of the rotational direction. Additionally, increasing the ratio of porous media/enclosure volume above 75% does not significantly impact the Nusselt number.

Geopolymer materials have garnered significant attention as sustainable alternatives to traditional Portland cement-based materials. This study explores the effect of various curing regimes on the compressive strength (at 7 and 28 days) and flexural strength (at 28 days) of geopolymer mortars composed of fly ash (FA) and metakaolin (MK) in varying proportions. Four mixes were used: 100% FA; 60% FA+ 40% MK; 50% FA+10% OPC+ 40% MK; and 100% OPC. The binders were activated using 15% sodium silicate (solid content) with an alkali modulus (Ms = SiO2/Na2O) equal to 1. The curing conditions included ambient curing and elevated temperature curing at 80 °C under different setups. The results demonstrate that the curing regime significantly influences the mechanical properties of alkali-activated mortars (AAMs). Where, the results showed that heat curing regime enhanced the flexural, early-age compressive strength and the microstructure, in comparison with other regimes. The findings provide valuable insights into optimizing curing practices for geopolymer mortars to achieve desired mechanical properties. Replacing 40% of fly ash with metakaolin improved the microstructure of the matrix and decreased micro-cracks.

Fossil fuel has been an energy source for decades which has been causing large emissions of CO2 and consequently has negatively influenced the climate of earth. For this reason, there has been large demand for new resources of energy that are eco-friendly for the environment. Exchange the energy sources needs engineering materials that have ability to convert the energy from one image to another. Oxide glasses are considered inorganic materials. They gain an interest for wide range of engineering applications of energy like in solar panels because They appear strength and good resistance for environmental conditions; in addition to good thermal stability and feasibility of shaping and processing. However, there still are challenges of implementing glass in energy applications. This short review will highlight the main challenges of oxide glasses and will present some ideas for them.

The combustion characteristics of ammonia/hydrogen/air mixtures have garnered significant attention due to their potential as carbon-free energy carriers. This review synthesizes previous studies on the turbulent flame behavior of these mixtures, focusing on flame speed, stability, ignition delay, and emission profiles. Ammonia, while a promising zero-carbon fuel, exhibits low reactivity and flame speed, which can be enhanced by blending with hydrogen. Hydrogen, known for its high reactivity and diffusivity, significantly improves the combustion performance of ammonia. However, the addition of hydrogen also introduces challenges such as increased NOx emissions and flame instability under certain conditions. Experimental and numerical studies have explored the effects of hydrogen blending ratios, equivalence ratios, and turbulence intensity on flame characteristics. The review highlights the importance of understanding turbulent flame behavior for optimizing the use of ammonia/hydrogen mixtures in practical applications such as power generation, internal combustion engines, and gas turbines.

This literature review examines the applications and advancements of the Kalina cycle in the context of renewable energy growth. The Kalina cycle, an improvement on the traditional Rankine cycle, offers enhanced efficiency for power generation from low-grade heat sources. This review synthesizes recent research on Kalina cycle implementations in geothermal, solar thermal, and most waste heat recovery applications, such as industry, diesel engines, and marine engines, as well as contributions to the augmenting power, desalination process, and the field of cosmic space. Also, studying a binary solution as the working fluid and the reason for selecting the ammonia-water mixture; additionally, discussion of the issues of corrosion and material compatibility. Finally, mention the correlation core of thermodynamic properties for analysis of the Kalina cycle. The findings indicate that while the Kalina cycle shows promise for improving renewable energy utilization, further research and development are needed to address efficiency, cost, and implementation barriers.