Automotive Experiences

Effectiveness of HNO3 and NaOH Pretreatment on Lignin Degradation in Areca Leaf Sheath Fibre (Areca catechu L.) for Bioethanol Production

Wahyuti Wahyuti — 2025-08-15

Areca leaf sheaths are underutilized waste but have a high cellulose content of 72.27%, so they can be utilized for bioethanol production. This research aims to utilize areca leaf waste for bioethanol production through acid (HNO₃ 5%) and alkaline (NaOH 10%) pretreatment processes, enzyme hydrolysis, and fermentation. Pretreatment using 5% HNO₃ and 10% NaOH solutions is carried out because it can break down the lignin bond and release it from cellulose and hemicellulose fibers. The enzymatic hydrolysis process uses cellulase enzymes at 37 °C for 48 hours to produce glucose. Glucose content analysis uses the DNS method and UV-Vis spectrophotometry instruments because it is accurate and can detect glucose in low concentrations. The fermentation process is carried out using Saccharomyces cerevisiae as a fermentation microorganism because it has high efficiency in bioethanol production for a duration of 3, 5, and 7 days. Based on the results of the analysis, pretreatment with HNO₃ 5% solution reduced the level of lignin in areca leaf sheaths by 2.31%. Meanwhile, pretreatment using a 10% NaOH solution lowered lignin levels to 1.81%. Reduced sugar levels after hydrolysis after pretreatment with HNO₃ 5% and NaOH 10% were 25.08 mg/mL and 16.37 mg/mL, respectively. The highest concentration of bioethanol in the 5% HNO₃ pretreatment was achieved on the 7th day at 16.75%, while that of 10% NaOH on the 5th day was 14.75%. This difference is influenced by the availability of fermentable sugars, where HNO₃ substrates take longer to decompose by S. cerevisiae than NaOH substrates. Based on the analysis, the bioethanol contains ethanol, thus the areca leaf sheath fibre feedstock has the potential to assist in the advancement of a sustainable biorefinery process that can reduce dependence on fossil fuels and increase added value.

Catalyst-Free Pyrolysis of Mixed Tyres and Plastic Waste for Heavy Fuel-Oil Production with Distillation

Janter Pangaduan Simanjuntak — 2025-08-27

Waste from used tires and plastics poses a significant environmental challenge due to their non-biodegradable nature. These materials take hundreds to thousands of years to decompose naturally. Every year, plastic and tire waste increase in correlation with population growth and vehicle usage. This waste management is frequently insufficient, resulting in significant adverse effects on human society. One of the effective solutions to the environmental challenges posed by used tires and plastic waste is converting them into crude oil and solid char using pyrolysis technology without a catalyst. This process is a thermochemical decomposition that occurs at high temperatures without oxygen. Pyrolysis breaks down the complex chemical structure of plastics and tires into simpler, valuable components. After being cut into small pieces of 3 cm to 5 cm, the feedstock was placed into a pyrolyzer, with each batch weighing 500 grams, to produce pyrolytic liquid oil and char. The pyrolysis temperature was set at 350 ℃ for all experiments, with a heating rate of 10 ℃/min and a holding time of 90 minutes. The process was followed by distillation at two different temperatures, 250 ℃ and 350 ℃, with a heating rate of 10 ℃/min. This distillation process separated the pyrolytic oil based on its boiling points to obtain distillate liquid oil. Two types of distillate liquid oil were produced and analyzed using gas chromatography and mass spectrometry to determine their chemical composition and compounds. It was found that both distillate oils contained similar organic compounds, primarily consisting of complex mixtures of C12–C31 hydrocarbons, which are typical of heavy fuel oils. The heating value of both distillate oils was 31.26 MJ/kg. Additionally, the residual char produced during the process had a calorific value of 21.73 MJ/kg, indicating its potential use as a solid fuel. These properties demonstrate the potential of the products to substitute conventional fuels for heavy machinery or industrial boilers. This study confirms that used tires and plastic waste can be converted into heavy fuel oils, offering great potential as alternative energy sources.

Optimised Flywheel-Assisted Regenerative Braking for Enhanced Energy Recovery and Voltage Stability in Electric Vehicles

Jafar Masri — 2025-08-27

This study presents a flywheel-assisted regenerative braking system (FARBS) designed to improve energy recovery and voltage stability in electric vehicles (EVs). Conventional regenerative braking systems (RBS) suffer from short energy retention durations and voltage fluctuations, limiting their efficiency. The proposed system incorporates a spherical shell flywheel (120 mm radius, 20 mm thickness, 3 kg mass) directly into the braking mechanism to prolong energy recovery and optimise braking efficiency. Experimental results demonstrate a 439% increase in energy recovery duration, extending from 1.15 seconds (2000 RPM) to 6.2 seconds (4500 RPM). Voltage retention improves significantly, increasing from 10.3V to 19.2V, ensuring sustained voltage delivery. Kinetic energy storage attains 580 J at 4500 RPM, exhibiting a 23.4% increase over 2000 RPM. The flywheel system quadruples power output longevity, sustaining 6.40 W for 6.2 seconds at 4500 RPM, compared to 2.2 seconds without the flywheel. Energy recovery efficiency peaks at 16 J at 4500 RPM, an improvement of 275% in comparison to the baseline 4 J. Optimisation analysis confirms that increasing flywheel mass (1 kg to 3 kg) improves energy recovery by 194%, while a spherical shell flywheel improves energy recovery, achieving 327 J. This is twice as much as that of a solid disk (162 J). Carbon fibre outperforms steel, boosting energy recovery by 94%, while increasing the thickness from 10 mm to 20 mm, and resulting in a 200% efficiency gain. These findings underline the superiority of flywheel-assisted energy recovery, paving the way for high-efficiency braking solutions in EVs, public transportation and railway networks.

Plasma Enhanced Ionic Liquid Catalysis for the Production of Biodiesel from Chicken Skin

Yasir Ali Elsheikh — 2025-08-28

Biodiesel production has emerged as a promising area of alternative fuel development, though challenges remain in sourcing cost-effective raw materials and selecting effective catalysts. This study investigates the production of biodiesel from chicken skin fat using two distinct catalytic methods. In the first method, transesterification was catalyzed by trioctyl ammonium hydrogen sulfate (Oct3AMHSO4) at concentrations ranging from 3-6 wt%. In the second method, the same catalyst was combined with plasma to enhance the reaction. The first method yielded only 35% biodiesel with 3.5 wt% Oct3AMHSO4, while the second method, under identical conditions, showed a significant improvement, achieving a 97.4% yield. The impact of temperature variations (40-80°C) was also explored with different catalyst concentrations (3-6 wt%). Increasing the catalyst concentration to 3.5% and raising the temperature to 55°C resulted in a notable yield improvement. However, further increases in temperature or catalyst concentration beyond 3.5% led to a decline in yield, particularly at temperatures exceeding 60°C. This suggests that certain reaction conditions may reverse the transesterification process, pushing the products back toward the reactants and reducing efficiency.

Enhancing Stoichiometric Methane-Air Flames: The Role of N2O Replacement

Aris Purwanto — 2025-09-02

The oxidizer is used in aviation propellants for its relatively high impulse density and non-toxic nature. At elevated temperatures, nitrous oxide (N₂O) decomposes into approximately 33% oxygen (O₂) and 67% nitrogen (N₂), providing a higher oxygen content than ambient air. This decomposition enables N₂O to produce higher flame temperatures than air. Previous studies have shown that N₂O addition improves flame stability in methane combustion systems. This study examined the substitution of O₂ with N₂O in stoichiometric methane–air premixed flames, using both numerical and experimental methods. One-dimensional and two-dimensional simulations with CHEMKIN PRO revealed that replacing air with N₂O increases flame temperature but reduces laminar flame speed, mainly due to lower local oxygen concentrations in the reaction zone. The simulations also showed that nitrogen oxides (NOₓ) emissions increase significantly in the post-reaction zone, while carbon monoxide (CO) and carbon dioxide (CO₂) emissions decrease. Experimental results confirmed that controlled N₂O addition enhances flame stability, but excessive concentrations can trigger combustion instabilities. Overall, the findings indicate that introducing up to 20% N₂O can increase flame temperature and reduce CO emissions in methane flames.

Innovative Pickup Car Cooling System Based on Thermoelectric Coupled With Heat Pipe Sink

Ragil Sukarno — 2025-09-02

Pickup cars are one of the most important means of transportation in the distribution of goods and logistics. However, many customers choose pickup cars without air conditioning because they are less expensive and more energy-efficient, resulting in lower operating costs. Car air conditioning systems generally utilize vapor compression systems, which consume a significant amount of energy. Additionally, some studies on thermoelectric cooling face challenges due to incompatible and difficult-to-install designs within vehicle cabins. To address this issue, this research was conducted on developing an innovative compact air conditioning (AC) system for the cabin of a pickup car. This system utilizes thermoelectric cooling (TEC) combined with a heat pipe sink. This cooling system features a practical and installation-friendly design compared to previous work, which can be integrated into existing pickup models without significant modifications. It is designed as a cooling box that generates and circulates cold air within the cabin. In this testing, the cooling box comprises six-unit thermoelectric cooling, where each unit varies using one-stage TEC modules and two-stage TEC modules. A 175-watt and 200-watt heat was applied and varied in the cabin to simulate the cooling load, and the air outlet duct's velocity also varied at 2 m/s and 3 m/s. The results showed that the thermoelectric cooling systems can significantly reduce cabin temperature increases, lowering the rise by 11.0 °C for a single-stage TEC system and by 10.8 °C for a double-stage TEC system compared to the cabin without a cooling system. The highest COP value of 1.4 was obtained in the single-stage TEC cooling system at a velocity of 3 m/s. The results show the potential of an innovative thermoelectric cooling (TEC) system when combined with heat pipes, offering an alternative cooling solution for the cabin of a pickup car. This proposed cooling system can be adapted for vehicles that require compact and energy-efficient cooling solutions.

Hydrogen-induced Fuel System in RCCI Engine for Clean Combustion: A Review

Eswanto Eswanto — 2025-09-02

Research in the field of internal combustion enigine using environmentally friendly fuels must be the main focus to increase efficiency, engine performance, reduction of exhaust gas emissions to clean combustion. Reactivity Controlled Compression Ignition (RCCI) on the diesel engines can be used as an innovative solution to increase thermal efficiency and reduce emissions through bending of fuels with different reactivity. This paper presents a comprehensive review of hydrogen-induced fuels systems on RCCI engines, as well as its impact on engine performance, emissions to Clean Combustion. Various studies show that mixing hydrogen in RCCI engines can increase thermal efficiency, speed up the combustion process, and reduce nitrogen oxides (NOx), particulate metter (PM), carbon monoxide (CO), hydrocarbons (HC) and Smoke Opacity emissions. This review provides insight into the trend of development of hydrogen-induced RCCI on diesel engines and its prospects in realizing a clean and efficient combustion system, so that future research focus is important for finding appropriate fuel mixtures, operating parameters, and choosing optimal engines by considering technical problems, thermodynamics, economics, and the environment, as well as exploring the potential implementation of this technology in the future.

Hybrid Catenary-Battery Trains for Non-Electrified Sections and Emergency Use

Muhammad Nizam — 2025-09-25

The hybrid catenary–battery system offers a promising solution for railways operating in non-electrified sections and during emergencies, ensuring uninterrupted operation, enhanced safety, environmental sustainability, and cost efficiency. This study addresses the challenge of determining an appropriate battery size and introduces a novel rule-based Energy Management Strategy (EMS) with coasting mode to minimize energy consumption while meeting operational requirements. The novelty of this work lies in (i) a straightforward sizing method based on worst-case emergency scenarios and (ii) the integration of coasting-mode operation into a rule-based EMS for hybrid catenary–battery trains. Simulation results show that the proposed approach achieves up to 12.56% energy savings on 3% gradient tracks while fully supplying auxiliary loads, compared with baseline operation that provides only partial coverage. These results demonstrate a practical and scalable framework for designing efficient, reliable, and resilient railway transport systems.

Multi-Objective Optimization of Structural Design for Lightweight Vehicle Chassis

Dharma Maheswara — 2025-09-25

This study presents a systematic optimization of a lightweight vehicle chassis design using Design of Experiments (DoE), Finite Element Analysis (FEA), and Analysis of Variance (ANOVA) to enhance structural performance while balancing mass efficiency and safety factor. Material selection and wall thickness variations were considered to achieve a compromise between minimal mass and a safety factor of at least 1.5. Pareto front analysis, combined with the Taguchi method, identified the optimal solution, Cycle Design 11, which achieved a safety factor of 1.9489, representing an increase of 0.7681 compared to the baseline design. The total mass of 3.5742 kg reflects a 32.13% increase from the baseline. ANOVA results confirmed that both material and wall thickness significantly influence safety factor and mass, providing critical guidance for design decisions. This multi-objective optimization approach demonstrates that integrating FEA with experimental design enables superior chassis designs compared to traditional single-objective methods, offering a practical strategy for developing lightweight, safe, and energy-efficient vehicles.

An Investigation of Pull and Push Factors in the Commercialization Policy of Electric Motorcycles in Indonesia

Fiky Two Nando — 2025-09-25

The ongoing energy crisis underscores the pressing need for more efficient energy utilization, particularly in the transportation sector. In this regard, the shift from conventional fossil fuels to electric vehicles (EVs) is essential for achieving both environmental sustainability and energy efficiency. Several developing countries, including Indonesia, have introduced regulations to promote EV adoption. However, electric motorcycle sales remain stagnant due to persistently low adoption rates. The primary challenge lies in the limited success of commercialization efforts, which continues to hinder broader market penetration in Indonesia. This study aims to identify research opportunities that can support the commercialization of EVs in Indonesia and to explore the push and pull factors influencing this process. An exploratory approach is employed, incorporating bibliometric analysis using R 4.3.1, a scoping literature review, and in-depth interviews with EV experts. The bibliometric analysis highlights the considerable development potential of electric motorcycle commercialization. From in-depth interviews with eleven experts, forty-four influencing factors were identified: twenty-nine of which are newly emerging factors, and fifteen are already established in the literature. Among these, four pull factors were confirmed, while twelve push factors were consistently highlighted by the experts. “Inexpensive product price for consumers” emerged as the most dominant pull factor in accelerating electric motorcycle commercialization, whereas the provision of incentives was the most frequently emphasized push factor driving supportive commercialization policies.

Development and Evaluation of Passive Balancing System Model for Lithium-Ion Battery Pack in Electric Vehicles Using Numerical Simulation

Vu Hải Quan — 2025-09-25

Electric vehicles (EVs) are increasingly becoming a crucial solution to mitigate environmental pollution and ensure energy security. Batteries, particularly Lithium-ion batteries, are the core component that determines the performance, range, and durability of EVs. However, managing and balancing the state of charge (SOC) among hundreds of cells in a battery pack is a significant challenge due to its complexity and high accuracy requirements. This study addresses these gaps by developing an integrated electro-thermal passive balancing model that combines Thevenin equivalent circuit modeling with dynamic thermal analysis and Stateflow-based MOSFET control logic, specifically designed for EV battery pack applications under realistic urban driving cycles. The passive voltage balancing process is designed to maintain voltage homogeneity among cells, thereby enhancing the pack's efficiency and lifespan. Initial assumptions are made to reduce model complexity (3 Lithium-ion cells), although this may lead to some discrepancies with real-world scenarios. Simulation results show that charging and discharging processes are efficiently managed, with SOC balancing among cells being maintained nearly perfectly after several cycles. Voltage, current, and temperature plots demonstrate stability and uniformity in cell operation thanks to the passive balancing mechanism. However, the current model is limited in reflecting real-world conditions, such as continuous changes in speed and load when the vehicle is in motion. This study provides insights into the operation of EV battery packs through electro-thermal modeling, while suggesting future directions to improve the model's realism and applicability in diverse operating scenarios. The results emphasize the importance of cell balancing in optimizing performance and prolonging the lifespan of EV battery systems.

Experimental Stress Analysis on Frame Structure of A 70-Passengers Electric Bus

Stevanus Brian Kristianto — 2025-09-25

Structural strength testing of buses using static vertical load has not previously been explored to validate the structural integrity of bus frames. In this study, the static vertical load method was employed to validate the structural strength of the Universitas of Indonesia electric bus, which utilizes two different materials SS400 for the lower frame and Aluminum Alloy 6061 for the upper frame. Finite Element Analysis (FEA) was conducted to identify critical areas on both the lower and upper frames. The stress values in the simulation were also obtained at the same location as the strain gauge placements in the experiment. Experimental vertical load testing was carried out by incrementally applying a load of 1000 kg up to the equivalent of 70 passengers, with an additional dynamic coefficient of 30% resulting in a maximum load of 6850 kg. Strain measurements were taken using 20 strain gauges on the lower frame and 8 on the upper frame. The experimental result showed the highest stress occurred at strain gauge no. 9 on the lower frame, measuring 78.10 MPa, and 15.32 MPa on the upper frame under 6850 kg load. The comparison between the simulation and experimental results reveals an 18% deviation. Nevertheless, both methods indicate the same critical area of the structure. The stress distribution indicated that the central deck area of the lower frame, where passengers sit and stand, experienced the highest loads. On the upper frame, significant stress was observed in the area where the air conditioning system is mounted. These findings demonstrate that static vertical load testing can be effectively used to validate the structural strength and stress distribution of electric buses, particularly in areas subject to concentrated loading.

Catalytic Pyrolysis of Plastic Waste for Gasoline Fuel: Reaction Mechanism Engine Integration

Enzo Wiranta Battra Siahaan — 2025-09-25

The escalating accumulation of plastic waste demands not only scalable but integrative conversion solutions. Among thermochemical routes, catalytic pyrolysis has emerged as a promising pathway to produce gasoline-range hydrocarbons from plastic polymers compatible with spark-ignition engines. This review critically evaluates recent advancements in pyrolysis of key plastics polypropylene (PP), polyethylene (PE), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC) with a focus on fuel yield, hydrocarbon distribution, and engine-level performance. Comparative analysis reveals PP as the most viable feedstock, achieving up to 85% liquid yield and producing oil with high Research Octane Numbers (RON 85–95), outperforming PE and PS in combustion efficiency and emission compliance. However, persistent challenges such as fuel instability, catalyst deactivation, and elevated aromatic emissions particularly from PS complicate real-world deployment. The review further dissects the interplay between catalyst type, reactor design, and post-treatment, highlighting how these variables modulate product quality and engine operability. Notably, 10–20% PP/PE-derived pyrolysis gasoline blends demonstrate near-parity with conventional gasoline in Brake Thermal Efficiency and regulated emissions, without requiring engine modifications. This work bridges molecular-level reaction chemistry with combustion diagnostics and policy-aligned emission metrics, offering a rare multiscale synthesis. By articulating process-emission-performance trade-offs, it provides a strategic reference for researchers and practitioners aiming to scale waste-to-fuel systems within circular economy frameworks.

Synthesis of Waste Cooking Oil Based Bioadditive Through Transesterification and Its Feasibility as Lubricity Enhancer Bioadditives for Low-Sulfur Diesel Fuel: Preliminary Investigation

Yulfi Zetra — 2025-09-25

Desulfurization of diesel fuel, which is considered to reduce pollution, causes a decrease in its lubrication power. As a result, the friction between surfaces of the engine increases, and it wears out easily. Therefore, it is necessary to increase diesel fuel lubricity through the addition of additives. Waste cooking oil modified to 2-hydroxypropyl esters has a prospect to be a lubricity-enhancing bioadditive. Polar and non-polar groups contain in 2-hydroxypropyl ester can form a bilayer on the surface of the engine that prevents friction between metal components. Synthesis of 2-hydroxypropyl esters was carried out by transesterification at 150°C for 10 hours. The mole ratio of oil to propylene glycol was adjusted to 1:7 with the loading of CaO 7% w/w oil as catalyst. The yield of the product is 88.89%. The product was identified by Gas Chromatography-Mass Spectrometry (GC-MS). The result showed that 2-hydroxypropyl palmitate and 2-hydroxypropyl oleate have dominant relative abundance with percentages of 42.46% and 57.44%, respectively. According to the molecular review as preliminary investigation, this compound has the potential to deliver better lubricity than ester-only biolubricants. Therefore, 2-hydroxypropyl ester can be proposed as an alternative bioadditive for low-sulfur diesel fuel lubricity enhancer.

Aerodynamic Approach to Two-Passenger City Car Design: A Study of Square Back and Compact Shapes

Randi Purnama Putra — 2025-09-25

The development of lightweight electric cars for urban mobility requires efficient aerodynamic design without sacrificing space efficiency. This study presents a novel method by investigating the combination of a two-seater city car's compact dimensions and square back shape, which has not been extensively researched for low- to medium-velocity vehicles. This study's objective is to assess the design's aerodynamic performance using numerical simulations using the Computational Fluid Dynamics (CFD) approach. The vehicle model is designed with a compact body and square back, which is commonly used in small vehicles with high maneuverability requirements. The simulations are conducted at three different air velocity levels: 10, 20, and 30 m/s. The results of the study showed an increase in the value of the drag coefficient (C_d) along with an increase in flow velocity. At a velocity of 10 m/s, the C_d value was recorded at 0.4536. When the velocity increased to 20 m/s, the drag coefficient increased slightly to 0.4563. Further increases in velocity to 30 m/s resulted in a C_d value of 0.4581. This C_d value shows the consistency of aerodynamic performance with increasing velocity, with fluctuations that remain within the efficiency limits of lightweight vehicles. The pressure distribution contour shows high-pressure accumulation at the front and low pressure at the rear of the vehicle, which generates large turbulent wakes in the rear area and contributes to increased drag. These findings indicate that the square rear body design faces significant aerodynamic challenges. Therefore, design strategies such as adding a rear spoiler, using a rear diffuser, and optimizing the rear body angle are suggested as potential solutions to improve flow efficiency.

A Multidimensional Comparison Assessing the Viability of Electric Vehicles in Jordan Across Key Performance Metrics

Mohammad Ahmad Ben Tarief — 2025-09-29

This study presents the first field-based, OBD-II–supported comparison of an electric vehicle (Changan Eado EV300) and a gasoline vehicle (Kia K3, 2019) under realistic Jordanian driving conditions. Using a 100 km mixed-route test and annualized projections, we evaluate energy consumption, operating cost, greenhouse-gas emissions (including battery manufacturing amortization), dynamic performance, cabin noise/comfort, and payback of purchase-price premium. Results indicate that, under predominant home charging, EV energy costs are reduced by over 60% relative to the tested gasoline vehicle, and operational CO₂ emissions fall substantially when charged from a low-carbon grid; battery manufacturing increases lifecycle emissions but does not offset operational benefits under renewable charging scenarios. EVs deliver superior low-speed torque and smoother acceleration, while ICE vehicles retain advantages in raw range and refueling time. Payback of the purchase premium is estimated at ~5.6–7.5 years (without battery replacement) and can extend beyond a decade if mid-life battery replacement is required. Findings inform policy on charging infrastructure, tariff design, and battery-lifecycle management for Jordan and similar contexts.