Search Results (151)

This study provides a comparison between the impact of two gas fuels, compressed natural gas (CNG) and hydrogen (H₂), on the exhaust emissions of a single-cylinder diesel engine operating in dual-fuel mode. The analysis is conducted with a constant and maximum achieved gas-to-total-fuel ratio (K = 20% and K = max) under varying load conditions, specifically at an engine speed of 2000 min⁻¹ and brake mean effective pressures ranging from 0.2 to 0.43 MPa. The results reveal that H₂ significantly improves the engine’s emissions profile compared to CNG. When H₂ is used as the secondary fuel, reductions in soot, carbon monoxide (CO), carbon dioxide (CO₂), and unburned hydrocarbons (CHs) are more pronounced. However, under certain load conditions, nitrogen oxide (NO_x) emissions are higher with H₂ than with CNG and can even surpass those observed during diesel-only operation. These findings suggest that while H₂ demonstrates superior overall emissions performance, its impact on NO_x emissions under specific conditions requires further optimization to maximize environmental benefits. Full article

The decarbonization of transport demands efficient, low-carbon alternatives to conventional fuels, particularly in regions where full electrification remains constrained. This study investigates the retrofitting of a 1.3 L Geely MR479Q spark-ignition engine for hydrogen operation, combining experimental measurements and one-dimensional numerical simulations in GT-SUITE. The baseline gasoline model was experimentally validated in 12 operating conditions and extended to the full map. In addition, the fuel was changed in the numerical model, and evaluations of hydrogen combustion through predictive sub-models considering mixture formation and pressure-rise limits were performed. Results show that the hydrogen engine operates stably within a wide air–fuel ratio window (λ = 1.0–2.7), with brake thermal efficiencies peaking at approximately 29%, surpassing gasoline operation by up to 5% in the mid-load range. However, port fuel injections cause a reduction in volumetric efficiency and maximum power output due to air displacement, a limitation that could be mitigated by adopting direct injection. A practical hydrogen conversion kit was defined—including injectors, cold-type spark plugs, electronic throttle, and programmable ECU—and the operational cost was analyzed. Economic parity with gasoline is achieved when hydrogen prices fall below ~6 USD kg⁻¹, aligning with near-term green-hydrogen projections. Overall, the results confirm that predictive numerical calibration can effectively support retrofit design, enabling efficient, low-emission combustion systems for sustainable transport transitions. Full article

In 2023, the bicycle industry in Taiwan reached a historic high. However, concerns about carbon emissions persist, particularly during the material acquisition and manufacturing stages of bicycle production. This study utilizes the Life Cycle Assessment (LCA) method, using SimaPro 9.5 for cradle-to-gate carbon emission data analysis. This study thoroughly examines the complete life cycle of a bicycle brake cable product through a carbon reduction evaluation tool, identifying carbon hotspots in the product’s life cycle. The data reveals that packaging accounts for the highest proportion of factory carbon emissions in the brake cable product analysis (34.42%), followed by the product’s casing (30.60%), with the leading materials being metal, plastic, and paper. Throughout the cradle-to-gate process, we collaborated with product developers to utilize the LCA carbon reduction evaluation tool to analyze the life cycle of the brake cable product. By aligning market and development needs, we supported manufacturers in identifying additional carbon reduction strategies at the material selection, mechanical design, and manufacturing process stages. These strategies include using natural raw materials, reducing packaging volume, developing lightweight products, and investing in integrated equipment. By implementing these measures, companies can reduce the product’s carbon footprint and enhance resource efficiency during production. This assessment tool serves as a communication bridge between designers and engineers, translating LCA quantitative data into references for design and management decision-making. It also functions as a simplified analytical tool for SMEs to conduct preliminary diagnosis of carbon emission hotspots and plan improvement directions, particularly suitable for manufacturers lacking consulting resources and carbon inventory capabilities. The research findings not only help companies integrate carbon reduction thinking early in product development, forming a closed-loop system of quantitative analysis and design actions, but also provide concrete references for Taiwan’s bicycle industry to promote supply chain collaboration, achieve green transformation, and meet global carbon reduction goals. Full article

Cashew nut shell liquid (CNSL) is a byproduct of cashew processing that has largely been overlooked as a biomass resource for biodiesel production. While some research has been conducted on CNSL in diesel engines, there remains a lack of studies on using processed CNSL with industrial waste catalysts for diesel engines. This study focuses on the performance and emissions of catalytically cracked CNSL (CC-CNSL) created with fly ash as a catalyst. Blends of 25%, 50%, 75%, and 100% CC-CNSL-diesel were used as a fuel in a single-cylinder diesel engine under different load conditions. The CC-CNSL25 blend, which contains 25% CC-CNSL, outperformed the others with a 2% increase in brake thermal efficiency. Additionally, it showed substantial reductions in emissions, i.e., 11.76% less carbon monoxide, 9.09% reduced smoke density, 8.57% lower hydrocarbon emissions, and 5.27% decreased specific fuel consumption compared to conventional diesel at full load. This research highlights fly ash-catalyzed CNSL processing as an effective method for converting agricultural waste into high-quality biodiesel. It offers a dual advantage as a sustainable fuel source while addressing waste management challenges. Full article

To address the dual challenges of fossil fuel depletion and environmental pollution, developing clean, renewable alternative fuels is an urgent need. Biomass gas, including biomass syngas and biogas, offers significant potential as an internal combustion engine alternative fuel due to its widespread availability and carbon-neutral properties. This review summarizes research on biomass gas application in dual-fuel diesel engines. Firstly, biosyngas and biogas production methods, characteristics, and purification needs are detailed, highlighting gas composition variability as a key factor impacting engine performance. Secondly, dual-fuel diesel engine operating modes and their integration with advanced low-temperature combustion technologies are analyzed. The review focuses on how biomass gas affects combustion characteristics, engine performance, and emissions. Results indicate dual-fuel mode effectively reduces diesel consumption, emissions, while its carbon-neutrality lowers life-cycle CO₂ emissions and generally suppresses NO_x formation. However, challenges include potential BTE reduction and increased CO and HC emissions at low loads. Future research should prioritize gas quality standardization, intelligent combustion system optimization, and full-chain techno-economic evaluation to advance this technology. Overall, this review concludes that dual-fuel operation with biomass gases can achieve high diesel substitution rates, significantly reducing NO_x and particulate matter emissions. However, challenges such as decreased brake thermal efficiency and increased CO and HC emissions under low-load conditions remain. Future efforts should focus on gas composition standardization, intelligent combustion control, and system-level optimization. Full article

This study systematically investigated the influence of catalyst formulation parameters (precious metal loading and Pt/Pd ratio) in diesel oxidation catalysts (DOCs)+catalyzed diesel particulate filter (CDPF)+selective catalytic reduction (SCR) on gaseous pollutant emissions from diesel engines. Results indicate that under varying conditions, the impact of catalyst formulation on DOC system performance—such as temperature rise characteristics, pressure drop, and brake specific fuel consumption (BSFC)—remains limited. Notably, exhaust temperature exerts a decisive influence on carbon monoxide (CO) and hydrocarbon (HC) conversion efficiency, significantly outweighing the impact of exhaust flow rate. Increasing precious metal loading and Pt proportion markedly optimizes CO and HC ignition characteristics by lowering ignition temperatures. However, under high-load conditions, conversion efficiencies across different catalyst formulations tend to converge. Specifically, under low-load conditions, a competitive adsorption mechanism between CO and HC causes HC conversion efficiency to exhibit an inverse trend relative to CO. Furthermore, higher precious metal loading and Pt content significantly enhance the catalyst’s NO₂ formation capacity at equilibrium temperatures, while higher Pd content contributes to improved thermal stability. Higher precious metal loading and Pt content increase nitrogen oxides (NO_x) conversion efficiency. CDPF possesses the ability to further oxidize NO. Full article

In this study, cottonseed oil biodiesel and waste lard biodiesel were produced through a transesterification process and blended with conventional diesel at different ratios (B10 and B20). The performance and emission characteristics of these fuels were systematically evaluated in a single-cylinder, four-stroke, water-cooled diesel engine operating at speeds of 1000–1800 rpm under a constant 50% load. The physicochemical properties of the fuels were analyzed, and engine parameters including brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), exhaust gas temperature (EGT), and emissions of carbon monoxide (CO), hydrocarbon (HC), carbon dioxide (CO₂), and nitrogen oxides (NOx) were measured. The results demonstrated that, compared with diesel, biodiesel blends significantly reduced CO, HC, and CO₂ emissions. At 1800 rpm, the LB20 blend showed reductions of 31.03% in CO, 47.06% in HCs, and 19.14% in CO₂ relative to diesel. These reductions are mainly attributed to the higher oxygen content and lower hydrogen-to-carbon ratio of biodiesel, which promote more complete combustion. However, all biodiesel blends exhibited higher NOx emissions than diesel, with the increase being more pronounced at higher blend ratios. At 1800 rpm, the LB20 blend recorded the highest NOx emissions, which were 20.63% higher than those of diesel under the same condition. In terms of performance, biodiesel blends showed higher BSFC and lower BTE compared with diesel, mainly due to their lower calorific value and higher viscosity. The lowest BTE and the highest BSFC were both observed with the LB20 blend, at 22.64% and 358.11 g/kWh, respectively. Full article

The growing dependence on fossil fuels has raised concerns over energy security, resource depletion, and environmental impacts, driving the need for renewable alternatives. Coffee husk, a widely available agro-industrial residue, represents an underutilized feedstock for biodiesel production. In this study, biodiesel was synthesized from coffee husk oil using a two-step transesterification process to address its high free fatty acid content (21%). Physicochemical analysis showed that Coffee Husk Oil Methyl Ester (CHOME) possessed a density of 863 kg m⁻³, viscosity of 4.85 cSt, and calorific value of 33.51 MJ kg⁻¹, compared to diesel with 812 kg m⁻³, 2.3 cSt, and 42.4 MJ kg⁻¹. FTIR analysis confirmed the presence of ester carbonyl and C–O functional groups characteristic of CHOME, influencing its combustion behavior. Engine tests were then conducted using B0, B10, B30, B50, and B100 blends under different loads, both with and without fuel preheating. Results showed that neat CHOME (B100) exhibited 11.8% lower brake thermal efficiency (BTE) than diesel, but preheating at 95 °C improved BTE by 5%, with preheated B10 slightly surpassing diesel by 0.5%. Preheating also reduced brake-specific fuel consumption by up to 7.75%. Emission analysis revealed that B100 achieved reductions of 6.4% CO, 8.3% HC, and 7.0% smoke opacity, while NOx increased only marginally (2.86%). Overall, fuel preheating effectively mitigated viscosity-related drawbacks, enabling coffee husk biodiesel to deliver competitive performance with lower emissions, highlighting its potential as a sustainable waste-to-energy fuel. Full article

This work provides a systematic evaluation of the performance and regulated emissions of binary n-pentanol–diesel blends under steady-state conditions, thereby clarifying condition-dependent efficiency–emission trade-offs across multiple loads and speeds. A single-cylinder, air-cooled diesel engine was operated at two speeds (1700 and 2700 rpm) and four brake mean effective pressure (BMEP) levels (0.25–0.49 MPa) using commercial diesel (D100) and three n-pentanol–diesel blends at volume ratios of 10%, 30%, and 50% (designated D90P10, D70P30, and D50P50, respectively). Brake thermal efficiency (BTE), brake specific energy consumption (BSEC), and brake specific fuel consumption (BSFC) were measured alongside exhaust emissions of nitrogen oxides (NO_x), carbon monoxide (CO), hydrocarbon (HC), carbon dioxide (CO₂), and smoke opacity. The results show that due to a lower cetane number, high latent heat of vaporization, and reduced heating value, n-pentanol blends incur efficiency and fuel consumption penalties at light to moderate loads. However, these disadvantages diminish or reverse at high loads and speeds: D50P50 surpasses D100 in BTE and matches or improves BSEC and BSFC at 2700 rpm and 0.49 MPa. Emission data reveal that the blend’s fuel-bound oxygen and enhanced mixing provide up to 16% NO_x reduction; 35% and 45% reductions in CO and HC, respectively; and a 74% reduction in smoke opacity under demanding conditions, while CO₂ per unit work output aligns with or falls below D100 at high load. These findings demonstrate that optimized n-pentanol–diesel blends can simultaneously improve efficiency and mitigate emissions, offering a practical pathway for low-carbon diesel engines. Full article

The present contribution showcases the potential brake emission reduction with Cr₂O₃ (chromium oxide) and WC-CoCr (tungsten carbide–chromium–cobalt) rotor coatings, as realized in our joint public–private research consortium. Particulate matter (PM) emissions from automotive braking systems have been characterized using a pin-on-disc tribometer equipped with particle measurement devices: a CPC (Condensation Particle Counter), an APS (Aerodynamic Particle Sizer), an SMPS (Scanning Mobility Particle Sizer), and a PM_2.5 sampling unit. Brake pad samples made from the same low-steel friction material were tested against a grey flake cast iron disc and two types of custom coated discs: a Cr₂O₃-coated disc and a WC-CoCr-coated disc. The friction pairs were investigated at a constant contact pressure of 1.2 MPa while the sliding velocity varied during the test, starting with 25 sequences at 3.6 m/s, followed by 19 sequences at 6.1 m/s, and finishing with 6 sequences at 11.2 m/s. The test results show encouraging 64% to 84% reductions in particle number (PN) emissions between 4 nm and 3 µm and 84% to 95% reductions in mass emissions (PM_2.5) thanks to the respective coated discs. SEM-EDXS (Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy) analyses show that the hardness and roughness of the discs, the chemical reactivity (oxidation), and the abrasiveness of the three friction pairs are parameters that might explain this reduction in emission. Full article

Grey cast iron brake discs with lamellar graphite (GJL) offer excellent strength and thermal conductivity but are prone to wear and dust emissions. To mitigate these issues, a multilayer coating was applied via Laser Metal Deposition (LMD), comprising a 316L stainless steel base layer and a WC-reinforced top layer. This study examines the microstructural evolution of the coatings under simulated thermomechanical and corrosive conditions using a brake shock corrosion test. Microstructural characterization was performed via Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD), focusing on grain size, orientation, and texture before and after testing. EBSD analysis revealed significant grain coarsening, with sizes increasing from below 20 µm to 30–60 µm, and a shift toward <101> texture. Hardness measurements showed a reduction in the WC-reinforced layer from 478 HV to 432 HV and in the 316L base layer from 232 HV to 223 HV, confirming the influence of thermomechanical stress. SEM analysis revealed a transition from horizontal cracks—caused by residual stress during LMD—to vertical microcracks propagating from the substrate, activated by braking-induced loads. These findings provide insights into the microstructural response of LMD coatings under realistic service conditions and underscore the importance of grain boundary control in designing durable brake disc systems. Full article

Ensuring traffic safety within urban public transport systems is essential for achieving sustainable urban development, particularly in densely populated metropolitan areas. This study investigates the integration of artificial intelligence (AI) technologies to enhance safety performance in closed public transport environments, with a focus on the city of Belgrade as a representative case. The research aims to evaluate how AI-enabled systems can contribute to the early detection and reduction of traffic incidents, thereby supporting broader goals of sustainable mobility, infrastructure resilience, and urban livability. A hybrid methodological framework was developed, combining computer vision, supervised machine learning, and time series analytics to construct a real-time risk detection platform. The system leverages multi-source data—including video surveillance, onboard vehicle sensors, and historical accident logs—to identify and predict high-risk behaviors such as harsh braking, speeding, and route adherences across various public transport modes (buses, trams, trolleybuses). The AI models were empirically assessed in partnership with the Public Transport Company of Belgrade (JKP GSP Beograd), revealing that the most accurate models improved incident detection speed by over 20% and offered enhanced spatial identification of network-level safety vulnerabilities. Additionally, routes with optimized AI-driven driving behavior demonstrated fuel savings of up to 12% and a potential reduction in emissions by approximately 8%, suggesting promising environmental co-benefits. The study’s findings align with multiple United Nations Sustainable Development Goals, particularly SDG 11 (Sustainable Cities and Communities) and SDG 9 (Industry, Innovation, and Infrastructure). Moreover, the research addresses ethical, legal, and governance implications surrounding the use of AI in public infrastructure, emphasizing the importance of privacy, transparency, and inclusivity. The paper concludes with strategic policy recommendations for cities seeking to deploy intelligent safety solutions as part of their digital and green transitions in urban mobility planning. Full article

This study focuses on the influence of different brake pad formulations on the emission of particulate matter coming from car braking systems. The brake particles were characterised using a pin-on-disc bench and some particle measuring devices such as CPC, APS, SMPS and a PM₁₀ sampling unit. Seven samples of brake pad materials of different compositions (1 NAO and 6 Low Steel) were tested against grey cast iron discs. The results presented in this work show differences in particle number concentration and PM₁₀ emission factor between the different friction materials tested. Three friction materials, LS04, LS06 and NAO01, reduce particle number emissions by up to 71% and PM₁₀ emissions by up to 57%. On the other hand, this reduction in particulate emissions goes along with a reduction of 20% to 27% in the coefficient of friction. The microscopic analyses carried out on the test parts (pins and discs) show differences between the most emissive and the least emissive friction pairs, which may explain the differences observed in particle emissions. Correlations between the emission of particles and the concentration of iron of the PM₁₀, as well as the steel fibre content in the formulas, were found. Full article

As internal combustion engines (ICEs) remain dominant in maritime transport, reducing their greenhouse gas (GHG) emissions is critical to meeting IMO’s decarbonization targets. Ammonia (NH₃) has gained attention as a carbon-free fuel due to its zero CO₂ emissions and high hydrogen density. However, its low flame speed and high ignition temperature pose combustion challenges. This study investigates the combustion and emission performance of NH₃-diesel dual-fuel engines, applying Response Surface Methodology (RSM) for multi-objective optimization of key operating parameters: ammonia fraction (AF: 0–30%), engine speed (1200–1600 rpm), and altitude (0–2000 m). Experimental results reveal that increasing AF led to a reduction in Brake Thermal Efficiency (BTE) from 39.2% to 37.4%, while significantly decreasing NO_x emissions by 82%, Total hydrocarbon emissions (THC) by 61%, and CO₂ emissions by 36%. However, the ignition delay increased from 8.2 to 10.8 crank angle degrees (CAD) and unburned NH₃ exceeded 6500 ppm, indicating higher incomplete combustion risks at high AF. Analysis of variance (ANOVA) confirmed AF as the most influential factor, contributing up to 82.3% of the variability in unburned NH₃ and 53.6% in NO_x. The optimal operating point, identified via desirability analysis, was 20% AF at 1200 rpm and sea level altitude, achieving a BTE of 37.4%, NO_x of 457 ppm, and unburned NH₃ of 6386 ppm with a desirability index of 0.614. These findings suggest that controlled NH₃ addition, combined with proper speed tuning, can significantly reduce emissions while maintaining engine efficiency in dual-fuel configurations. Full article

At present, environmental pollution is becoming more and more serious, and the energy problem is becoming more prominent. Energy-braking recovery can collect the mechanical energy lost in the traditional braking process and convert it into electricity or other forms of energy for vehicle reuse, thus reducing carbon emissions, achieving energy saving and emission reduction, and promoting green development. Based on this, this paper studies the energy-braking recovery method. The study focuses specifically on the recovery of energy during vehicle braking triggered by brake-signal activation, without addressing alternative deceleration strategies under braking conditions. The proposed energy-braking recovery scheme is evaluated primarily through simulation, with the analysis grounded in practical application scenarios and leveraging existing technologies. Firstly, the principle of energy-braking recovery is introduced, and the method of estimating the State on Charge (SOC) of the battery and controlling the motor speed is determined. Then, the simulation model of the energy brake recovery system is built with MATLAB R2023b (MathWorks, Natick, MA, USA), and the design ideas and specific structures of the three modules of the simulation model are introduced in detail. Finally, the results of the simulated motor speed and SOC value of the battery are analysed, and it is confirmed that they meet the requirements of the system and achieve close to the ideal effect. Full article