Metallurgical and Materials Engineering (E-Journal)
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Multivariate Analysis of the Main Operational Variables Involved in Steel Producing on BOF Using Time Series Tools
Get PDFThere is significant interest in accurately modeling the operational variables of the steel-making process in LD converters. Despite this, the task is challenging due to the complex interactions between process variables, which are not entirely comprehended. Often, decisions in the industry are grounded in experience. This study aims to introduce a robust model that can effectively guide engineers and technicians by forecasting the future behavior of steelmaking variables in the BOF furnace. We employed multivariate time series analysis to reach this goal, utilizing tools like Vector Autoregression models, ElasticNet, K-Nearest-Neighbors, Multiple Linear Regression, and Long Short-Term Memory Neural networks. These models were tested on data from three distinct steel production campaigns. A successful model was identified, predicting 35 out of the 42 chosen variables, demonstrating the potential to correlate a majority of the selected parameters
Effect of the inclination angle of finned cylinder over a BFS on the MHD behavior in the presence of a nanofluid
Get PDFThe present numerical study is based on the forced magnetohydrodynamic (MHD) convection of a ferrofluid through a backward facing step (BFS). A cylinder with two fixed fins and fixed dimensions is implanted inside fluid. The dimensionless governing equations have been solved using the multigrid finite element method. Several parameters were considered, such as the Hartmann number 0≤ Ha ≤100, the magnetic field inclination angle 0°≤ ɣ ≤90°, the Reynolds number 10≤ Re ≤200, the nanoparticle volume fraction 0%≤ φ ≤10%, and the fins inclination angle 0°≤ a ≤180°. The results have shown that the presence of the fins improves the heat transfer, especially at the position a = 90° where the Nuave number increases with a ratio of 113% for Re = 200.
Numerical Optimization Of Heat Exchanger Design Using Newton-Raphson And Genetic Algorithms
Get PDFOptimization of heat exchanger performance continues to be an essential component of thermal engineering, with applications that span a broad range of sectors, including the energy sector, aerospace, and the process industry. It is common for traditional design techniques to have difficulty striking a balance between opposing goals, such as the efficiency of heat transmission, the pressure drop, and the cost. For the purpose of improving the design of shell-and-tube heat exchangers, this research proposes a comparative numerical optimization framework that integrates the Newton-Raphson method, which is a deterministic iterative methodology, with Genetic Algorithms (GAs), which are a probabilistic, evolutionary-based heuristic. Maximizing the rate of heat transmission while simultaneously minimizing pressure drop and material consumption are the goal functions that are taken into consideration. In order to solve the nonlinear governing equations of the exchanger's thermal performance, the Newton-Raphson approach was used. On the other hand, the GA was utilized for the purpose of conducting all-encompassing searches inside the intricate, multi-dimensional design space. In order to guarantee the dependability of the results, we used benchmark datasets and empirical correlations that are customary in the industry. MATLAB was used to develop each of the approaches, and then this software was used to test them against real-world data that was gathered from the Heat Exchanger Design Handbook (HEDH). Genetic algorithms outperform the Newton-Raphson technique when it comes to handling highly nonlinear and limited optimization situations, as shown by numerical findings. This is despite the fact that the Newton-Raphson approach provides quick convergence given appropriate beginning circumstances. The dual-strategy method is a compelling improvement for industrial thermal system designers, since it guarantees optimization that is both durable and efficient
Numerical investigation of the nanoparticles nature effect on the MHD behavior in a square cavity with a metallic obstacle
Get PDFIn this paper, a study is conducted to determine numerically the effect of the nanoparticles nature (Al2O3, CuO, and Fe3O4) on the thermo-magnetohydrodynamic behavior of a nanofluid in a square cavity with a circular obstacle. The left wall of this cavity is movable and provided with a cold temperature (Tc) and the right wall is exposed to a hot temperature (Th). However, the upper and lower walls are considered adiabatic. The purpose of this paper is to highlight the effect of aluminum dioxide, copper oxide, and iron trioxide nanoparticles on the thermal and hydrodynamic behavior under the influence of different volume fractions(0 ≤ φ ≤ 0.1), different Hartmann numbers (0 ≤ Ha ≤ 75) and Richardson number (0 ≤ Ri ≤5). The system of governing équations was solved by the finite element method adopting the Galerkine discretization. The obtained results showed that the CuO nanoparticles improve the heat transfer at the fluid and obstacle, in addition, the increase of Hartmann number reduces the heat capacity, especially with the use of Fe3O4 nanoparticles. This study falls within the context of improving the cooling rate of industrial equipment.
Assessment of mechanical and tribological performance of hybrid Al/MoS2/Al2O3 composite by GFRA
Get PDFThis work emphasizes the mechanical and tribological performance of Al-Si/Al2O3/MoS2 hybrid matrix composites. The composites are reinforced by varying weight percentages of Al2O3 (8%, 12%, and 16%) and MoS2 (0%, 2%, and 4%), and were prepared by stir casting. As the weight percentage of Al2O3 in a composite grows, so does its hardness and tensile strength. The addition of 2% wt. MoS2 enhances the specific strength and tribological properties, according to the research. However, when compared to other composites studied, the Al/16% Al2O3 composite had improved mechanical properties. MoS2 also aids the hybrid composite in achieving higher tribological characteristics while marginally lowering the specific strength. Taguchi orthogonal array (L27) is used to design tribological performances with process parameters viz. applied load, sliding speed and weight % of Al2O3 as well the percentage of MoS2 whereas wear rate (mm3/m), wear (µm) and coefficient of friction were considered as the responses. A hybrid Grey–Fuzzy Reasoning Approach (GFRA) is used to optimize a multi-response for avoiding vagueness in decision making. The statistical analysis revealed that Al/2%MoS2/16%Al2O3 composite has exhibited better wear resistance than other composites. The confirmation test is also conducted to validate the optimal condition obtained by ANOVA.
Effect of thermal aging above the glass transition temperature on the mechanical properties of rigid PVC tube
Get PDFThermal aging of standard samples of rigid PVC (u-PVC) taken from plastic tubes near and above the glass transition temperature (Tg) was used to investigate the effect of elevated temperatures on the mechanical properties of rigid (u-PVC) tubes used in industrial areas. Three aging protocols were used, each lasting 90 days at 80 °C, 100 °C, and 120 °C. Crosslinking and chain scission reactions changed the tensile properties, either increasing them or decreasing them. For all three aging protocols, it was discovered that Young's modulus increased with aging time. Furthermore, the rate of increase of the modulus was observed to increase with aging temperature. The Yield stress showed the same pattern. Their increase in both cases is due to material stiffening caused by a crosslinking process. This last one was revealed by DSC, where Tg increased as a result of the chemical process. The decrease in elongation at break, which occurred progressively in all aging protocols and more precisely at temperatures above Tg, on the other hand, demonstrated the relationship between chain scissions and temperature. The material becomes more brittle as the temperature rises. Brittleness is caused by a high activity of chain scissions on the surface sample, which allows micro-cracks to form. When subjected to tensile forces, cracks propagate from the surface toward the sample's thickness.
Optimization and analysis of dry sliding wear behaviour of N-B4C/MOS2 unreinforced AA2219 nano hybrid composites using response surface methodology
Get PDFThe effect of heat treatment on nano-size B4C particle reinforced hybrid composites is discussed in this paper. For this, hybrid reinforced AA2219 composites with 2% by weight nano B4C and 2% by weight MoS2 particulates were fabricated using a two-stage stir casting process, and the specimens were heat treated to assess their influence on wear behavior. Experiments were carried out to study the wear behavior by varying important factors such as aging temperature, load, and sliding distance. Response Surface Methodology (RSM) designed by Box-Behnken was used to identify the critical variables influencing wear rate and optimize wear behavior. To comprehend the wear mechanisms involved, an analysis of the worn surface was presented. Based on the analysis, a regression equation with a predictability of 97.2% was developed for the response to obtain the optimum wear rate. The following order effectively captures the relative importance of the various factors determining the alloy's wear resistance: sliding distance, load, and aging temperature. When compared to load and sliding distance, heat treatments via artificial aging in the temperature range of 200-240 °C have no significant effect on the wear resistance of hybrid AA2219 composites reinforced with n-B4C and MoS2 particulates. However, when a temperature range of 200-240 °C is considered, composites exhibit better wear resistance at the aging temperature of 240 °C with ice quenching
Development and investigation of the technological process of plasma carbothermal reduction of slag from secondary metallurgy of aluminum
Get PDFBased on a critical analysis of the current state and prospects of development of the problem of pyrometallurgical recovery/extraction of aluminum from aluminum-bearing industrial waste, the need to replace traditional, electrocarbonothermic processes and melting process units with innovative, plasma carbothermal processes and furnace-reactors, with the possibility of reverse feeding and recovery of gasified during melting metal and metal oxide components is substantiated. On the basis of this analysis a new technological scheme of smelting with a new design of plasma-arc furnace-reactor, which provides a solution to the problem using a special hollow double-shell graphite cathode connected to the system of circulating supply of gases separated from the reaction zone, was developed and presented. The proposed technological scheme also differs in the use of such highly active liquid and gaseous reagents as carbon-containing reducing agents as calcium carbide (CaC2) and methane (CH4). The main features of chemism of reducing processes are described. It is shown that by replacing traditional coke with anodized calcium carbide and natural gas (methane) the recovery rate of aluminum oxide (Al 29-34%) and silica (SiO2) and hematite (Fe2O3) present with it increases to 80-99%. Specific power consumption is reduced by 35-40%, the 90-95% reduction in the loss of target elements, the 80% reduction in the emission of greenhouse carbon dioxide, which is replaced by a very valuable recyclable synthesis gas - CO-H2. By additionally feeding separate portions of quartzite and steel-rolling scale in the furnace-reactor, a complex alloy-ligature of Fe-Si-Al-Ca system is melted, with the ratio of components: 1:[1.3-2]:[1.3-1.2]:[0.9-1.25]. With the introduction into industrial practice of the plasma carbothermal process of aluminum reduction from secondary aluminum dumping slags accumulated in the world (4 million tons/year), it will be possible to return up to 1-1.5 million tons/year of aluminum to the production processing cycle
Compressive behavior of perlite/sodium silicate composite foam modified by boric acid
Get PDFIn this work lightweight expanded perlite/sodium silicate composite foams were manufactured with varying quantities of boric acid (BA) 0-2.88 wt.%. The composites were characterized for density, compressive strength (CS), compressive modulus (CM), and energy absorption (EA) up to 50% strain. The compression tests were also conducted at various crosshead speeds to evaluate the strain rate dependency of the foams. The hygroscopic tests were done to evaluate water absorption properties and investigate the effects of water absorption on the compressive properties of the foams. The CS, CM, and EA of the foams increased for a boric acid content of 0.74 wt.%, but further addition of BA caused a gradual decrease in these characteristics. The range of sp. CS (3.80-5.93 MPa/(g/cm3)) achieved were found to be well compatible with the values of building materials in the literature. The foams appeared to be sensitive to the strain rate in compression, causing variations in the compressive properties as well as the trends of stress-strain curves. Furthermore, the addition of BA in the composite reduced water absorption up to a BA content of 1.46 wt.%. The compressive properties were also highly influenced by the hygrometric test
Sandwich composite of aluminum alloy and magnesium alloy through accumulative roll bonding technique
Get PDFAluminum and magnesium alloys are lightweight materials with outstanding technical uses. Due to their combined qualities, composites built of aluminum and magnesium alloys have surpassed the utilization of these elements individually. Accumulative Roll Bonding was used to create a three-layered sandwich composite structure made of Al-alloy/Mg-alloy/Al-alloy. The composite structure's microstructure and mechanical characteristics were studied. A fine-grained AZ31 layer was formed, according to the microstructural study. At the Al-alloy/Mg-alloy contact, a diffusion layer was also seen. On the broken surface, fractography exhibited both ductile and brittle failure characteristics