Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Fire Risk Assessment of Subway Tunnel Linings with Different Exposed Surface Areas
No full textThe impact of fire on underground tunnels can vary significantly with differing patterns of heat exposure, potentially leading to structural failure. Using a circular tunnel case study, a framework for fire risk assessment of the tunnel lining with different exposed surface areas has been established. A critical reduction factor is proposed for modifying the moment-axial force interaction diagrams derived for a pre-specified fire exposure duration to quantify the risk of structural failure. The results show that the worst-case scenario is when the internal surface area of the tunnel lining is partially exposed to fire above its mid-height, as opposed to a complete exposure of the internal surface area. Moreover, this study underscores the critical impact of fire through a combined effect of axial forces and bending moments within the lining section, as compared to its load-bearing capacity. The proposed technique has shown merit in assessing fire risk, particularly when the time to failure of the lining structure is not known before analyzing the impact of fire
Optimizing Briquette Performance of Mushroom Cultivation Waste Omah Jamur Ungaran Used the Taguchi Method: Circular Economy Approach
Get PDFIndonesia ranks 75th of 166 countries receiving an achievement from the Sustainable Development Goals (SDGs). The main factor in the success is the appropriate sustainable waste management, which utilizes alternative energy sources to support a circular economy. One potential use for biomass waste generated from oyster mushroom cultivation is wood powder briquettes. The main ingredient of powder briquettes is the waste oyster mushroom cultivation of wood powder. Omah Jamur Ungaran is a Small Medium Enterprise (SME) that specializes in cultivating white oyster mushrooms. However, the cultivation process generates considerable waste. This study focused on two essential variables: moisture content and ash content. The research employs the Taguchi method as a parameter. The method considers five factors: water volume, baglog charcoal, tapioca, blending time, and drying oven temperature. The results indicate a ranking order of the factors: the first is drying oven temperature (in Celsius); second is water volume (in ml); third is baglog charcoal (in grams); fourth is tapioca (in grams); and fifth is blending time (in minutes). The optimal conditions demonstrated 50 ml of water volume, 66 grams of baglog charcoal, 20 grams of tapioca, a blending time of 3 minutes, and a drying oven temperature of 140°C. Under these conditions, the best ash content results were observed by values ranging from 11.7% to a maximum of 30%
Predictive State of Charge (SoC) Modeling using Machine Learning Algorithms in Lithium-Ion NMC Batteries
Get PDFThe State of Charge (SoC) estimation is crucial in lithium-ion batteries to prevent excessive charging and discharging, impacting the battery's safety, stability, and efficiency. Conventional techniques are the most frequently employed method for estimating SoC. However, they are less accurate in predicting SOC due to their computational sensitivity and difficulty adapting to complex environments. This study proposed four machine learning models: Linear Regression, Multilayer Perceptron, Decision Tree, and Random Forest that were applied for SoC prediction on lithiom-ion NMC batteries. The models' performance was evaluated based on Correlation Coefficient and error values (Mean absolute error or MAE and Root mean square error or MRSE). Based on the result, the Random Forest model exhibited the best performance with a Correlation Coefficient of 1, and MAE and MRSE values of 0.2052 and 0.2712, respectively. Conversely, the Linear Regression model demonstrated the worst performance, with a Correlation Coefficient of 0.9534 and MAE and MRSE values of 5.9064 and 8.2602, respectively
Utilizing CNC Router Machine to Construct a Prototype Incorporation Principles of Solid-based Rapid Prototyping Process and Interlocking Brick Design
Get PDFIntegrating user-friendly concepts into product design fosters innovation, addressing design thinking gaps and minimizing the risk of overinvestment in trial-and-error prototypes. Driven by a “technology-push platform,” manufacturers often prioritize product identity over universal design. However, a shift towards standardization promotes user autonomy and reduces costs. This approach empowers future generations to develop or enhance products efficiently through a do-it-yourself (DIY) approach. Upholding environmentally conscious manufacturing, strategic waste reintegration aligns with environmental goals and reduces costs. In CNC Router operations, repurposing unused material promotes sustainable practices. The main objective of the proposed research is to revolutionize rapid prototyping through the innovative use of interlocking brick design, addressing traditional prototyping challenges. This method eliminates the need for adhesives, simplifying assembly and enhancing structural integrity. The proposed research explores solid-based rapid prototyping and interlocking bricks, utilizing a CNC router. Designers optimize bricks through CAD and FEA analysis, facilitating rapid, adhesive-free prototyping. Emphasis on FEA analysis of mechanical properties, 3D slicing, tool selection, and material choice ensures the creation of functional prototypes. Key parameters, including FEA analysis of mechanical properties, slicing the 3D virtual model into layers matching the brick's thickness, appropriate tool selection, and material choice, are critical in achieving the desired outcomes. This comprehensive strategy aligns with a waste-to-wealth concept, illustrating the seamless integration of sustainable practices into innovative manufacturing processes, revolutionizing contemporary design and production. By adopting this approach, manufacturers can streamline production processes, reduce material waste, and enhance product adaptability, ultimately promoting user autonomy and cost reduction
Effect of Sintering and Various Fillers in Zirconia Composite Coating for High Temperature Application
Get PDFZirconia is a ceramic material that is relatively cheap and easy to purify from mineral form. Zirconia powder has stable properties under high temperature conditions making it suitable for use as a coating for steel substrates. Ceramic composite coating is one option that can be used to increase its durability by adding filler which has lubricant properties. In this research, hBN, MoS2 and graphite were used as filler coatings. The coating method used is slurry spray, which is a simple method and there is a subsequent sintering process so that the resistance of the coating to the substrate is better. The effect of the coating is seen before and after the sintering process on the surface and thickness. And to see the adhesion of the coating to the substrate, a thermal shock test was carried out. From the test results, it was found that sintering had a significant effect on the coating surface, where the defects on the coating surface became fewer and more even. The optimum temperature for sintering is 600oC where the least porosity is obtained
Water Electrolysis Technology Selection for Green Hydrogen Production in Coastal Isolated Area
Get PDFThe concept of utilizing excess electricity from Renewable Energy (RE), coupled with green hydrogen fuel cells, offers an alternative sustainable model for RE power plants in isolated regions. The selection of the appropriate electrolyzer is a crucial step toward establishing an efficient and sustainable system. This study was designed to assess which electrolyzer holds the most promise within the system’s design. Alkaline Water Electrolysis (AWE), Proton Exchange Membrane (PEM), and Anion Exchange Membrane (AEM) were considered as alternatives. The selection process was carried out using the Multi Criteria Decision Making method, incorporating four main criteria: technical, economic, social, health-safety-environmental aspects, alongside ten sub-criteria that encompass factors such as maturity, reliability, robustness, efficiency, investment cost, community acceptance, availability of electrolyzer companies, environmental impact, risk of harm, and land requirements. The criteria-subcriteria weighting process was conducted using the Analytical Hierarchy Process (AHP). Additionally, the ranking process employed three other methods: Technique for Order of Preference by Similarity to Ideal Solution, Simple Multi-Attribute Rating Technique, and Multi-Objective Optimization on the Basis of Ratio Analysis. In the final evaluation, considering the ranking based on both the baseline case and variations of weight in the range of 5-10%, it was consistently observed that PEM ranked highest
General Characterization of Whey Protein Extracted through Various Techniques: A Comparative Analysis
Get PDFA significant quantity of waste is generated by food processing industries worldwide leading to severe environmental and social challenges. Within the milk processing industry, the coagulation of insoluble proteins results in the production of copious amounts of effluents. This latter yields liquid rich in soluble proteins known as whey proteins. Various techniques, including the use of organic solvents, heat treatment, and lyophilization, are employed to extract these proteins. The objective of this research is to compare the extracted substances obtained with the commercially available product. Fourier-transform infrared spectroscopy (FT-IR) is employed as the analytical technique in this study. The FT-IR spectra of the extracted whey proteins exhibit characteristic peaks similar to those reported in the literature and the commercial product. These findings validate the effectiveness of the utilized extraction methods, and further steps should be considered to enhance the yield and quality of the extracted material. The findings provided insights into the suitability and quality of the extracted substances, paving the way for improvements in the extraction process. By maximizing the utilization of waste streams from the food transformation industry, this research aims to contribute to resource optimization and sustainability in line with environmental and societal considerations
Pusher Propeller Performance Investigation on Lightweight Medium Range UAV
Get PDFResearch has been conducted to investigate the efficacy of a pusher-type propeller on a Lightweight Medium-Range UAV aircraft using two methods: Computational Fluid Dynamics (CFD) simulation and experimentation. Since there is a fuselage at the front, the performance of the propeller on this UAV aircraft may experience interference, making it necessary to investigate. This investigation aims to determine the difference in thrust coefficient (CT), power coefficient (CP), and efficiency () between the performance of the propeller with and without the fuselage, as well as the aerodynamic efficiency (L/D) of the propeller. The testing and simulation will have two configurations: propeller with the fuselage (power-off and power-on) and propeller without the fuselage (power off and power on). According to the results, putting the propeller behind the fuselage would decrease CT and CP at the same advanced ratio point as the configuration without a fuselage. At the same advanced ratio position, the propeller efficiency of the configuration with fuselage drops by approximately 5%. The comparison of simulation results with experiments shows the same pattern. Speed changes do not significantly affect aerodynamic efficiency (L/D). Propeller rotation (power on) significantly affects the aerodynamic efficiency (CL/CD) by an average of approximately 82-87%
Structural Analysis of Mini Power Weeder Worm and Worm Gear with Three Different Materials
Get PDFThe main aim of this paper is to conduct the structural analysis of min power weeder worm and worm gear with three different materials. The objectives of this paper are to calculate the design of worm and worm gear, to draw the model of worm and worm gear by using AutoCAD 2019 software, to analyze the structural behavior of worm and worm gear by theoretical approach using von-Mises criteria and compare with numerical structural result using ANSYS 16.2 software, and to select the suitable material of worm and worm gear for good performance. A 2.5 hp engine power and 6000 rpm worm speed mini power weeder is used in this paper to do worm and worm gear bending stress analysis with material properties of phosphor bronze, aluminum bronze, and tin bronze material. For the phosphor bronze material, the lowest von-Mises stress and effective strain are obtained. Thus, phosphor bronze is found to be the suitable material for worm and worm gear
Comparative Assessment of Molten Salt Reactor Neutronic Performance with Various U-233 Purity
Get PDFMolten salt reactor (MSR) can be deployed as a thermal breeder reactor in a thorium fuel cycle. The fissile nuclide mostly uses U-233, which is nonexistent in nature and must be synthetised. Researches on thermal breeder MSR usually assume that the U-233 is pure, but in technical reality, U-233 synthesis always accompanied by other uranium isotopes. These impurities can affect the reactor physics performance and altering the operational safety consideration. This research studies the impact of using impure U-233 on the neutronic performance Passive Compact Molten Salt Reactor (PCMSR). Four U-233 vectors with various level of purity were used as comparison. The investigated parameters were reactor criticality, temperature coefficient of reactivity (TCR), kinetic parameters, and conversion ratio (CR). The calculations were performed using MCNP6.2 code with ENDF/B-VII.0 nuclear data library. From the calculation, impure U-233 fuels were proved to improve the TCR as a result of weaker moderator temperature coefficient (MTC). Whilst impurity does not particularly affect delayed neutron fraction, it reduces neutron generation time. Impure U-233 vectors slightly altered CR value, but rather insignificant. Overall, operational safety and CR value can be maintained even if the MSR core is started using low-purity U-233