Advanced Engineering Forum Vol. 54

Abstract: The present study deals with the investigation of the long term atmospheric corrosion phenomena for galvanized steel sheet in the region of Addis Ababa in Ethiopia using various atmospheric corrosion models. Addis Ababa have transforming atmosphere type of urban/industrial atmosphere, and these changes are going to affect the atmospheric corrosion phenomena for galvanized steel sheet used in this region, which is investigated through atmospheric corrosion models using atmospheric data collected from National Meteorology Agency, Ethiopia for 21 years from 2000 to 2020. Atmospheric corrosivity category for Addis Ababa is determined, and it is found that with little deviation in atmospheric pollutant these categories can shift between C2 and C3 corrosivity category for galvanized steel sheet atmospheric corrosion. Further to study the atmospheric corrosion of galvanized steel sheet, standard atmospheric corrosion models were employed namely Feliu et al. model and Kucera et al. model. These studies corroborate the findings of atmospheric corrosion of galvanized steel sheet and cross verified with the similar region atmospheric corrosion experimental studies performed earlier on the same material. All the atmospheric corrosion models confirmed the trend of the atmospheric corrosion of galvanized steel sheet in the region of urban/industrial atmosphere type. And based on the comparative analysis of all models predictions with experimental results in literature, it is confirmed that the atmospheric corrosion model results are reliable for the study of short and long period of atmospheric corrosion of galvanized steel sheet in Addis Ababa region.

Abstract: This study investigates the influence of cutting parameters on tool temperatures and residual stresses during the machining of aerospace alloys Inconel-718, Hastelloy-X, and Ti6Al4V. Experimental turning operations were conducted under predetermined cutting speeds, feed rates, and cutting depths, followed by residual stress measurements using X-ray diffraction (XRD). Maximum tool temperatures were recorded using a thermal camera. Additionally, numerical simulations were performed using DEFORM 3D under identical cutting conditions to validate the experimental findings. The results reveal that Hastelloy-X exhibited the highest residual stresses and cutting tool temperatures, while Ti6Al4V showed the lowest. A close agreement was observed between the experimental and simulation data, highlighting the accuracy of the DEFORM 3D model. This study provides a comprehensive analysis of Hastelloy-X, a material with limited prior research, contributing novel insights into its machining characteristics. The findings will aid in optimizing cutting parameters for improved performance and tool life in aerospace applications.

Abstract: In recent years, particular attention has been paid to the use of renewable energy, particularly biomass, for reasons related to both climate change and waste management. Biogas is frequently used in low value-added applications such as heating and fuel in engines, while it can be reformed into hydrogen, through certain process such as the process of dry reforming, of partial oxidation, of bi-reforming, or even of tri-reforming. The literature has indicated that the tri-reforming process is better than other reforming processes. Biogas tri-reforming is a simultaneous combination of endothermic dry reforming and steam reforming with exothermic methane oxidation, carried out in a single reactor to produce syngas which is an important feedstock for chemical production and energy vectors. Second, the process of tri-reforming overcomes several weaknesses of each main reform process. This article presents a new mathematical model of tri-reforming which will further optimize this type of process. The developed mathematical model was validated with literature data. Thus, the literature data used are among others, the optimal feed ratio in the tri-reforming process, CH₄/CO₂/H₂O/O₂ = 1:0.291:0.576:0.088. For optimal temperature and pressure, the data used are 1223 K and 5 bar respectively. This mathematical model makes it possible to achieve high conversion of methane (CH₄) and carbon dioxide (CO₂) coupled with high selectivity in hydrogen. The conversion rate of methane (CH₄) can reach 99% and that of carbon dioxide (CO₂) can reach 97%. The model is adapted with a high hydrogen selectivity: 2.88.

Abstract: Soil stabilization is crucial for enhancing the engineering properties of soil and constructing durable infrastructure, such as highways, airports, and roadways. The study's constituents were previously employed separately, and the soil's strength improved when they were coupled with other ingredients. Experimental investigations were conducted to assess the effects of varying proportions of C&D waste, CCR, and molasses on key soil characteristics, including compaction, shear strength, and plasticity. A series of crucial tests, including Atterberg limits, compaction characteristics, differential swell index, unconfined compressive strength (UCS), California Bearing Ratio (CBR), and Scanning Electron Microscope (SEM) analysis, were conducted to evaluate the performance of the stabilized soil. Test results indicated marked improvements in the Atterberg limits, reduced swell potential, and elevated values of UCS and CBR, demonstrating the effectiveness of the proposed stabilization method. CDW, CCR, and molasses enhance Unconfined Compressive Strength (UCS) by improving strength and cohesion. The addition of these chemicals significantly improved the performance of the soil, as seen by the decreased settling, enhanced strength, and greater infrastructure durability. Molasses served as an effective natural binder, while glass fibers improved tensile strength and durability by distributing stress evenly. This approach addresses waste management issues and promotes sustainable construction practices, offering a cost-effective solution for enhancing soil performance and paving the way for resilient infrastructure development.

Abstract: In this paper, a new method for solving Maxwell's equations associated with electrostatic separators is presented. The boundary value problem is transformed into an optimization problem by using the finite element method. Numerical simulations were carried out using Matlab software that performs equation-based multiphysics modeling for different physical processes by applying the finite element method and modified method of characteristics to a system of partial differential equations. The finite-element method is used to solve Poisson's equation, and a modified method of characteristics is used to satisfy the current continuity condition. The two methods are repeated to obtain a consistent solution to the described equations. The simulation model has been developed to determine the influence of the electrical conductor, semiconductor, and dielectric particles on the important parameters of the corona mechanism, namely the distribution of electric potential, electric field, current density, space charge density, and collection efficiency.

Abstract: This study presents the design, construction, and performance analysis of a cost-effective solar irradiance meter using photodiodes and operational amplifiers. The device employs a high-speed, low-noise AD8615 operational amplifier in a transimpedance circuit, integrated with a BPW34 photodiode sensor, and an averaging network to minimize noise. An ESP32 microcontroller facilitates remote monitoring by transmitting irradiance data to a Thingspeak server via Wi-Fi. Simulation results showed a correlation coefficient (R) of 0.999983 between current and irradiance, while practical tests demonstrated a correlation of 0.9961 between the device and a reference meter. The project achieved a significant reduction in cost, approximately 8% of traditional pyranometer prices. The strategy of using multiple photodiodes and averaging their outputs effectively mitigates noise and directional errors, making this device versatile for various solar irradiance measurement applications.

Abstract: In this study, the performance of a photovoltaic thermal (PVT) system with a rectangular absorber design using water-based nanofluids such as MWCNT/w, CeO₂/w, and TiN/w with a volume fraction of nanoparticles at 4% as a coolant is investigated. The mass flow rates varied from 0.025, 0.050 and 0.075 kg/s under meteorological conditions categorized as hot, cooled, and mixed in three different cities of India (Bengaluru, Delhi, and Srinagar). A numerical model was established to evaluate the performance of the PVT system by employing a heat balance equation for various components of the PVT system. Additionally, Taguchi assessment and ANOVA analysis were carried out to evaluate the effect of meteorological parameters and determine the optimum conditions. The highest daily electrical effectiveness and heat gain of the PVT system for the cities of Bengaluru, Delhi, and Srinagar were obtained with the CeO₂/w nanofluid at a mass flow rate of 0.075 kg/s, are 15.13%, 15.02%, and 16.14% and 282.5 Wh, 349.55 Wh, and 219.23 Wh, respectively, compared to the other nanofluids. Another optimal value of the effecting variable is obtained in CeO₂ nanofluid for electrical efficiency and heat gain of the PVT system where a mass flow rate, sun radiation, ambient temperature and wind velocity are 0.050 kg/s, 800 W/m², 32 °C, and 1.4 m/s, and 0.075 kg/s, 800 W/m², 22 °C, and 1.6 m/s, respectively and sun radiation was the most significant parameter for electrical efficiency and heat gain, with significant values of 81.66% and 92.35%, respectively.

Abstract: This article presents the results of optimizing the efficiency of a hybrid photovoltaic power plant using the fuzzy MPPT algorithm adapted to PID control for voltage regulation in order to overcome the voltage dip problem. The hybrid system consists of a photovoltaic field with a power of 11.2kW, a wind generator (WIND) of 12.23kW, the diesel group is used as an emergency source in the event of a power deficit and/or a voltage drop of more than 10% compared to the reference value. For this, the maximum powers of the photovoltaic generator (GPV) and the wind turbine are extracted independently by the fuzzy logic MPPT control. In addition, the two generators are coupled to the Buck-Boost chopper for voltage regulation by “proportional integral derivative” (PID) control. The hybrid system supplies an alternating load (AC) with an active power of 11kW. The entire system is controlled using fuzzy logic control whose input variables are the variation of the GPV-WIND hybrid power and the variation of the GPV-WIND hybrid voltage. The DC-DC converters used operate continuously and at a switching frequency of 10kHz under a temperature of 50°C. The originality and the contribution of this work lies in the fact that the entire hybrid system is modeled using MATLAB, thus making it possible to study its operation. The simulation results obtained are very satisfactory and show a particular interest in the search for stability and resolution of voltage dips thanks to intelligent control.

Abstract: The quick and accurate estimation of time-varying harmonics is crucial for online monitoring, analysis, and control of the electrical power system. This research paper presents a stationary wavelet packet transform (SWPT) based digital design implemented on the FPGA platform for efficient and fast amplitude estimation of the power system harmonics. The time-invariant property of the SWPT technique plays a crucial role in ensuring the accurate amplitude estimation of harmonic components. The efficiency and accuracy of the proposed SWPT-based digital design have been assessed with synthetic and experimental test signals generated on the MATLAB/Simulink platform. The SWPT technique has been implemented using Xilinx system generator (XSG)/Vivado design suite 20.1 on the Xilinx Artix-7 FPGA AC-701 board. Performance evaluation of the suggested SWPT-based digital design has been carried out in terms of timing requirements, resource utilization, and hardware accuracy with the stationary and time-varying power signals. With the reported performance parameters, the proposed digital design can estimate the power system's harmonics in a single fundamental cycle, or 20 milliseconds for a 50 Hz system. The results showed that the SWPT-based digital design is accurate and robust for estimating time-varying harmonics, demonstrating its practical usefulness. This highlights the potential for using the proposed approach in real-time applications within power systems, where precise harmonic measurement is crucial for efficient operations.

Abstract: The reliability of the distribution networks has been threatened by the disturbances which have occurred on the said networks and which have led to supply interruptions to customers. From the analysis of the faults that have occurred on these networks, it emerged that the most recurring disturbances are faults originating from external causes (atmospheric overvoltages, violent winds) and which represent 90% of the causes, transient faults (70%) and broken conductors (40%). The study of the reliability indices showed that the most disturbed departures are the MV departures from Ouidah, ITTA, Calavi and Togba whose SAIDIs are respectively 15.64; 13.9; 10.05; and 8.52. The optimization of the maintenance plan by genetic algorithms of the NSGA II type made it possible to identify the number of inspections which is 5 days and 11 days respectively during the rainy season and the dry season. The inter-inspection period related to these inspection periods is (21 days). This study led to the proposal of an optimal plan taking into account climatological criticalities and the aim of which is to reduce these disturbances which are more untimely in the rainy season. The resolution of the reliability problem by genetic algorithms of the NSGA-II type made it possible to deduce that the undistributed energies are reduced by 92.22% on the departure of Togba, 93.43% on the departure of ITTA and 95, 54% on departure from Ouidah. This energy could have brought Beninese Electricity Company (SBEE) a sum of nine hundred fifty-one million eighty-four thousand two hundred and fifty CFA francs (951,084,250 FCFA) on only three MV departures. This optimization denotes the technical and financial interest of SBEE by focusing more on strategies for reducing disruptions on its networks while giving priority to the rehabilitations, effectiveness and efficiency of its maintenance plans. The methodology used is efficient and effective and can allow SBEE to make substantial savings which will enable it to make a reinvestment in its distribution networks.