Browse Topic: Biofuels

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Experimental Investigation on Unburned Methanol and Formaldehyde Emissions from a Direct-Injection Diesel / Methanol Dual-Fuel Engine2026-99-1646To be published on 07/24/2026
For large-bore marine methanol / diesel dual-fuel engines, this study investigates the formation characteristics of unregulated emissions through experimental methods and explores the mechanisms by which engine load and injection timing influence the emissions of unburned methanol and formaldehyde. The study was carried out on a supercharged intercooled inline six-cylinder engine, and Fourier Transform Infrared Spectroscopy (FTIR) was used to monitor the exhaust composition in real time. The study shows that methanol released in the exhaust is due to the incomplete combustion of the methanol fuel. In the combustion process of methanol fuel, formaldehyde mainly arises from two pathways, the first of which is the partial oxidation of methanol inside the cylinder; secondly, the unburned methanol in the exhaust gas oxidizes in the exhaust pipe to generate formaldehyde. As the load increased from 25% to 100%, the unburned methanol emissions decreased by 29%, and formaldehyde emissions decreased by 71%. This is mainly attributed to the enhanced oxidation reaction and reduced wall crevice effect due to the increased combustion temperature. Methanol injection timing optimization was effective in controlling unregulated emissions, with methanol emissions lower at -7° CA ATDC and formaldehyde emissions reaching larger values under this condition. Delaying the diesel injection to -16°CA ATDC led to a 38% increase in unburned methanol emissions, caused by fuel spray interactions and longer stagnation, whereas formaldehyde emissions showed minimal change.
Jiang, Yuqi, Li, Hongmei, Zhang, Wenzheng, Li, Xiao, Zheng, Liang, Meng, Yangqian, Gu, Xianan, Hua, Hanqing
Study on Diesel-Methanol Non-Premixed Combustion Characteristics of a Marine Dual-Fuel Engine at Different Methanol Substitution Rate2026-99-05177/10/2026
Methanol use in marine engines has the potential to reduce nitrogen oxide emissions, particulates, and greenhouse gas emissions. A turbocharged four-stroke marine diesel powerplant was converted to run as a double-DI (direct injection) diesel-methanol hybrid engine. Experimental studies using a non-premixed combustion scheme showed that higher methanol substitution ratios (MSR) led to increased peak heat release rates. The combustion process displayed distinctive two-phase behaviors. Increasing MSR caused retarded ignition timing, shortened combustion duration, and improved thermal efficiency. Combustion stability was significantly improved at higher MSR. Emissions results showed NOX and HC were increased in proportion to MSR, whilst particulate emissions and CO concentrations were inversely reduced. Methanol enrichment was found to enhance NOX and HC formation processes but also accelerate soot particulate decomposition and CO oxidation mechanisms.
Li, Xiao, Jiang, Yuqi, Yan, Ping, Zheng, Liang, Li, Hongmei, Zhang, Wenzheng, Chen, Chao, Man, Zhongguo
Experimental Study of Warm-Up And Startability Operations in a Spark Ignition Engine Fueled with Ethanol Gasoline Blends2026-01-07387/1/2026
The mitigation of Greenhouse Gas (GHG) emissions poses a major challenge for the transportation sector, driving the need for renewable fuels. Bioethanol represents a promising fuel for Spark-Ignition (SI) engines, combining a reduced life-cycle CO₂ impact with advantageous combustion properties. However, despite its proven performance under steady-state conditions, the widespread of fuels with high ethanol content is still constrained by significant difficulties during engine cold-start operation. This study aims to experimentally assess the effect of ethanol concentration on cold-start performance and warm-up transient behavior of a Naturally Aspirated (NA), Port Fuel Injected (PFI) SI engine. Warm-up tests were conducted at an operating condition of 2000 rpm engine speed and 20 Nm torque using three fuels with increasing ethanol content: commercial gasoline (E5), E30 and E60. In addition, dedicated startability tests were carried out for E60 and neat ethanol (E100) at different initial engine wall temperatures to evaluate fuel sensitivity to thermal conditions during engine start. The experimental results indicate that increasing ethanol concentration has a negligible effect on the overall duration of the warm-up process, while leading to a modest reduction in both engine wall and exhaust gas temperatures. At the same time, E100 displays severe startability limitations at low initial wall temperatures, requiring repeated cranking attempts before stable operation can be achieved. The same startability issues have been observed for E60 but with limited intensity. Two minimum engine wall temperature ranges were identified for reliable cold-start operation at 20-25 °C for E60 and 25-30°C for E100. Overall, these findings experimentally confirm the dominant influence of engine thermal conditions on the reliable startability of ethanol-fueled spark-ignition engines.
Falbo, Luigi, Falbo, Biagio, Perrone, Diego, Castiglione, Teresa
Biofuel Effect on Regeneration Capability and Soot Reactivity in SCRoF Systems2026-01-07507/1/2026
Biodiesel blends (B7, B20, B100) were evaluated in a Stage V-compliant SCR on Filter (SCRoF) system for heavy-duty applications to quantify soot reactivity and filter regeneration capability. Compared to conventional diesel (B7), B20 showed slightly faster regeneration performance under real-driving conditions, while B100 resulted in reduced particulate formation and higher soot reactivity, with more intense exothermic events requiring careful management. These differences are attributed to the distinct physical-chemical properties of the fuels (oxygen content, lower heating value) and their interaction with Diesel Oxidation Catalyst (DOC)/SCRoF. All tests were conducted on an engine dynamometer with a Cursor 9 FPT (Fiat Powertrain). Findings are discussed in the context of EU Stage V limits and practical control strategies for heavy-duty applications.
Costa, Simone
Impact of High Compression Ratios on Ethanol Homogeneous Charge Compression Ignition2026-01-50386/10/2026
Ethanol requires elevated intake temperatures to initiate autoignition in Homogeneous Charge Compression Ignition (HCCI) as a high-octane single-stage fuel. To leverage the high thermal efficiency, low engine-out NOx, and near-zero soot inherent to HCCI with ethanol, a custom piston design was developed to enable high compression ratios (CR) up to 22.5:1. This study investigates HCCI combustion with ethanol at three CRs of 17.5, 20.0, and 22.5 through equivalence ratio and boost sweeps performed to assess the reduction in the intake temperature requirement at high CRs and the emissions and efficiency trade-offs. Results indicate a clear benefit with reduced intake temperature requirements with increasing CR. However, a combustion efficiency penalty was observed at high CRs. Three-dimensional Computational Fluid Dynamics (CFD) simulations were performed using Large Eddy Simulation (LES) coupled with a detailed chemistry model to investigate the underlying mechanisms of the combustion efficiency penalty. CFD results reveal that the combustion efficiency penalty at high CR is primarily due to increased crevice mass trapping unburned or partially oxidized species and a rapid expansion effect inhibiting complete carbon monoxide (CO) oxidation.
Vedpathak, Kunal, Kumar, Mohit, Motwani, Rahul, Datar, Aditya, Gainey, Brian, Lawler, Benjamin
Methane Emission Mitigation in Large-Bore Dual-Fuel Engines via Negative Valve Overlap Diesel Injection: Thermochemical Pathways and Reactivity Control2026-37-00456/9/2026
Low-load natural gas–diesel reactivity controlled compression ignition (RCCI) in medium-speed marine engines is constrained by an insufficient charge thermal state. This limitation leads to partial fuel oxidation, producing high methane emissions. This work evaluates the use of negative valve overlap (NVO) combined with NVO diesel injection as an in-cylinder reactivity enhancement strategy. The simulation study was performed using the University of Vaasa’s advanced thermo-kinetic multi-zone model (UVATZ), extended for reactive simulations during NVO. The extended framework was validated against test-bench data from a prototype Wärtsilä 6L20 dual-fuel engine operating in RCCI mode. The baseline low-load operating point for reforming simulations was defined by reducing the intake manifold temperature to replicate conditions close to partial misfire with 52% combustion efficiency. The parametric sweeps of NVO injection timing and ratio showed that the strategy can be used for in-cycle fast thermal management, effectively restoring complete combustion on an individual cycle basis. In simulated conditions, the best performance was obtained with an NVO injection ratio of 0.3, with the injection scheduled before top dead center. In contrast, increasing the NVO fraction beyond ~0.3 provided no benefit and led to complete misfire due to excessive reduction of main-event high-reactivity fuel. The simulations revealed a coupled thermal–chemical control mechanism. Early NVO injections stabilize combustion through recompression heat release and an increased next-cycle intake valve closing temperature. Sufficiently late injections stabilize combustion by carrying unreacted diesel into the subsequent cycle. Injections near NVO TDC primarily undergo fuel conversion to CO, H2O, and unsaturated light/mid-range hydrocarbons with negligible thermal boost, yielding an overall reactivity deficit.
Soleimani, Amir, Nurmi, Mikael, Hunicz, Jacek, Kim, Jeyoung, Hyvonen, Jari, Mikulski, Maciej
Development of a Diesel Combustion System for Next-Generation Heavy-Duty Engines Using a Synergistic Analysis-and-Testing Approach2026-37-00046/9/2026
Regulators and policymakers have introduced increasingly stringent limits on tailpipe CO₂ and pollutant emissions to accelerate the decarbonization of heavy-duty vehicle applications. The development of innovative propulsion technologies — such as advanced combustion systems, low-friction reciprocating components, and improved aftertreatment solutions — combined with hybridization and the adoption of alternative fuels (e.g., biogas, HVO, green hydrogen), is a key pathway for meeting future emission and GHG targets. In this study, advanced combustion systems were developed for a 13-liter diesel engine for heavy-duty truck applications, with the objective of meeting forthcoming Euro VII regulations while maximizing thermal efficiency. The combustion system architecture—including open-bowl geometry with high aspect ratio, injector nozzle with wider spray opening angle, and reduced swirl ratio—was optimized using a Machine Learning–algorithm trained on high-fidelity 3D CFD combustion data. The method enabled the identification of two optimized combustion-system “recipes”, one of which was evaluated through engine tests, which refined nozzle specifications and injection strategies, using a structured Design of Experiments (DoE) approach. Results were benchmarked against a MY24 baseline combustion system, assessing efficiency, NOx–soot trade-offs, and combustion behaviors. Based on 3D-CFD results, the advanced combustion concept achieved an improvement in Brake Thermal Efficiency (BTE) of up to +0.8% points and delivered substantial NOx reductions of up to 45%, while maintaining smoke emissions at or below baseline levels. The experimental results indicate that the advanced combustion system developments designed for next-generation heavy-duty engines can further increase BTE by up to ~1% relative to the baseline combustion system, without deteriorating the soot–NOx trade-off.
Belgiorno, Giacomo, Centini, Maria Pia, Pezza, Vincenzo, Cozza, Ivan F., Pesce, Francesco C., Vassallo, Alberto, Colombo, Giovanni, Gallo, Alessandro, Mirzaeian, Mohsen, Borg, Jonathan
Experimental Investigation on Cold Start and Warm-Up Phases for an Ethanol Fueled SI Engine2026-37-00316/9/2026
The reduction of Greenhouse Gas (GHG) emissions represents a key challenge for the transportation sector, requiring the adoption of renewable fuels capable of ensuring both environmental benefits and compatibility with existing internal combustion engine technologies. In this context, bioethanol emerges as a viable solution for Spark Ignition (SI) engines, offering a low life-cycle CO₂ footprint and favorable combustion characteristics. Nevertheless, despite its well-known advantages under steady-state operation, the widespread use of high-ethanol-content fuels is still limited by critical issues during engine cold start. The aim of this work is to experimentally investigate the influence of ethanol content on cold-start behavior and idle warm-up transient operation of a Naturally Aspirated (NA), Port Fuel Injected (PFI) SI engine. The experimental campaign was carried out under idle conditions using four fuels with increasing ethanol content, namely commercial gasoline (E5), E30, E60, and neat ethanol (E100). Cold-start and full warm-up tests were performed starting from ambient temperature, while additional dedicated experiments were conducted on E100 to evaluate startability under different initial engine wall temperatures. The results show that increasing ethanol content has a limited impact on the overall warm-up duration, while slightly reducing engine wall and exhaust gas temperatures. Conversely, E100 exhibits pronounced startability issues at low initial wall temperatures, requiring multiple cranking attempts to achieve stable idle operation. A minimum wall temperature threshold in the range of 25-30 °C was identified as necessary to ensure reliable cold start with E100. The outcomes of this study provide experimental evidence of the key role played by engine thermal conditions in enabling stable operation of ethanol fueled SI engines during cold start.
Falbo, Luigi, Falbo, Biagio, Perrone, Diego, Castiglione, Teresa
Alcohol-Based Energy Carriers in Transportation: Status, Standards, and Outlook2026-37-00426/9/2026
The global transport sector accounts for approximately 30 % of total final energy consumption and 15.9 % of worldwide greenhouse gas (GHG) emissions, with road transport alone accounting for the largest share at 11.8 %. Decarbonizing this sector requires energy sources that combine scalable generation from renewable sources with compatibility with various modes of transportation and existing infrastructure. Methanol and ethanol emerge as promising alternative energy carriers that can leverage existing logistics infrastructure while reducing dependence on fossil fuels. Global methanol production reached 112 million metric tons, and global ethanol production totaled approximately 93.5 million metric tons in 2024, compared to more than 2 billion metric tons of gasoline and diesel produced annually. The review assesses production pathways and cost trajectories for both alcohols, evaluates fuel requirements across multiple transport modes, including passenger vehicles, light- and heavy-duty vehicles, maritime shipping, aviation, and rail, and provides regulatory frameworks governing fuel standards in six major markets, the European Union, the USA, Brazil, China, Japan, and India. From a technical perspective, the internal combustion engine is examined in greater detail as the energy conversion system, synthesizing current combustion research on engine performance, emissions characteristics, and cold-start behavior. Current standards predominantly accommodate ethanol blending for spark-ignition (SI) engines in passenger vehicle applications, with permitted concentration limits ranging from 3 % in Japan to nearly pure ethanol in Brazil. Methanol applications remain more limited in road applications. In the maritime sector, recent ISO 8217:2024 specifications and International Maritime Organization (IMO) interim guidelines have established frameworks for the use of methanol and ethanol as marine fuels. Aviation remains the most restrictive sector, with alcohol fuels explicitly prohibited in certified aviation fuels due to material compatibility and safety concerns. To unlock the decarbonization potential of methanol and ethanol in the transport sector, coordinated policy support and continued technological innovation will be essential. As production scales and regulatory frameworks mature, both alcohol fuels may play an increasingly central role in the transition toward sustainable mobility.
Fitz, Patrick, Fellner, Felix, Rößlhuemer, Raphael, Härtl, Martin, Jaensch, Malte
Numerical Simulation of Spark-Ignited Flame Kernels towards Prospective Application to Hydrogen SI Engines2026-37-00156/9/2026
The ongoing energy transition demands the decarbonization of the transport sector, for which the use of premixed hydrogen in spark-ignition (SI) engines appears very promising. However, modeling the combustion of the lean hydrogen/air mixtures required for safe, efficient, and low-NOx engine operation involves multiple open issues. Correct prediction of flame kernel initiation and growth is a difficulty that hydrogen shares with hydrocarbon fuels, while properly accounting for the instabilities that characterize lean hydrogen flames is an additional demanding task. In this work, a 1D kernel expansion model of general validity recently proposed by the authors is implemented into OpenFOAM, an open-source 3D CFD software package, to enable numerical simulation of expanding spark-ignited flame kernels. Firstly, the OpenFOAM framework is presented focusing on XiFluid, its flame propagation model based on a regress variable whose evolution depends on the laminar flame speed. Then, the authors’ kernel expansion model, based on the transient thermo-diffusive theory, is briefly recalled to highlight its capabilities and outputs. The coupling between OpenFOAM and authors’ model is split into two stages, namely ignition and expansion. During the ignition stage, an artificial profile of the regress variable is temporarily imposed to ensure a stable numerical solution, following which the kernel expansion is simulated by feeding into XiFluid an equivalent flame speed extracted from the 1D model. The coupling is currently formulated for laminar kernels, simulations of which are conducted firstly for conventional fuels (methane and propane) and then for hydrogen. The results are validated against outcomes of experimental tests performed in a constant-volume combustion chamber operated by engine manufacturer Wärtsilä. The validation is satisfactory for all fuels, although minor disagreements appear in case of intense flame stretch. These will be addressed in future developments, which will also extend this approach to unstable turbulent hydrogen flames in SI engines.
Dotteschini, Enrico, Pretto, Marco, Giannattasio, Pietro, Gadalla, Mahmoud
EDITORIAL: Diversification key for sustainable fleets26TOFHP06_046/1/2026
We hear it often at industry events, in keynote speeches and during expert panel discussions: There is no silver bullet. Peter Voorhoeve, president of Volvo Trucks North America, says as much in this issue's Q&A (page 44). “Electric is one solution, but biodiesel is another solution, and hydrogen is, too. So we have these different fuel solutions to get to better sustainability.”
Gehm, Ryan
IN FUEL CONTROL26TOFHP06_026/1/2026
How to ensure off-highway combustion systems operate with sufficient control to meet tightening emissions standards and evolving fuel landscapes without sacrificing reliability. Off-highway equipment is being asked to do more with less. Less margin for emissions, less tolerance for downtime and less room for inefficiency, while operating under some of the most demanding duty cycles in the transport sector. Tier 4 and Tier 5 emissions standards have reshaped engine calibration strategies. Renewable diesel and biodiesel blends are entering worksites and farms at scale. At the same time, construction, mining and agricultural machines are expected to run for 20-25 years, often at sustained high load and far from service infrastructure. In this environment, combustion systems are far from being phased out.
Anderson, Todd
Effect of Burning Biomass Fuel Cyclohexanol on Diesel Engine Performance2026-99-17085/22/2026
Against the backdrop of growing global demands for energy sustainability and stricter emission regulations for diesel engines, this study investigates the performance implications of incorporating cyclohexanol—a renewable oxygenated fuel—into diesel fuel blends. Using a marine medium-speed diesel engine as the experimental platform, the research systematically evaluates engine performance and emission characteristics across a range of cyclohexanol-diesel blend ratios under low, medium, and high load conditions. Experimental findings reveal multifaceted effects of cyclohexanol blending on engine operation. Combustion of the blended fuels enhances the engine’s dynamic performance, particularly under medium and high loads, where the maximum in-cylinder burst pressure exhibits a noticeable increase. This improvement is attributed to cyclohexanol’s oxygen-carrying capacity, which promotes more vigorous and sustained combustion reactions. In terms of emissions, increasing the proportion of cyclohexanol in the fuel blend leads to significant reductions in soot and carbon monoxide (CO) emissions, reflecting the cleaner-burning properties of the oxygenated component. However, this is accompanied by an uptick in nitrogen oxide (NOx) emissions, likely due to the elevated combustion temperatures generated by the more efficient fuel oxidation process. From an economic perspective, cyclohexanol blending at consistent load levels induces a postponement in the crank angle at which peak heat release occurs during combustion. This temporal shift prolongs the effective combustion duration, enabling more complete fuel utilization within the cylinder. Consequently, fuel consumption rates decrease, and overall engine efficiency improves, highlighting the potential of cyclohexanol blends to enhance operational economy in marine propulsion systems. In summary, this study underscores the complex trade-offs associated with cyclohexanol-diesel blends: while they offer tangible benefits in power output, fuel efficiency, and reduced particulate emissions, managing the increase in NOx emissions remains a critical challenge. The results provide a foundational framework for advancing biofuel applications in marine engines, emphasizing the need for integrated emission control strategies to optimize the balance between performance and environmental sustainability.
Chen, Ke, Yang, Chenxi, Wang, Yibin, Fan, Jinyu, Liu, Yuchen, Ye, Zixiao, Huang, Jialiang
Effect of Injector Tip Temperature on Methanol Spray Dynamics during Cold-Start Conditions2026-01-03404/7/2026
Methanol is one of the most readily produced e-fuels and remains in liquid form at ambient conditions, making storage and transportation relatively simple. In the marine sector, methanol has already been actively adopted as a pathway toward carbon neutrality. For automotive sectors, methanol offers significant potential for carbon emission reduction owing to its higher octane number and lower carbon content compared with gasoline. However, its high latent heat of vaporization and low vapor pressure suppress evaporation at low ambient temperatures, leading to increased emissions during cold-start operation. To address this issue, previous studies have explored heating the injector tip or fuel rail to enhance evaporation and atomization. The present study focuses on visualizing and quantifying the improvement in methanol evaporation characteristics under cold-start conditions by applying controlled heating to the injector tip. Experiments were conducted in a constant-volume chamber where the ambient temperature was carefully regulated, while a laterally mounted injector tip was subjected to different heating levels. Extinction images were acquired to determine spatial and temporal liquid volume fraction and to visualize spray morphology and penetration behavior for both methanol and gasoline surrogate fuel E00. Moreover, three-dimensional tomography reconstructed from extinction images taken at multiple viewing angles provided an in-depth assessment of methanol spray structure, droplet distribution, and evaporation behavior with varying injector tip temperatures under simulated cold-start conditions. These findings highlight the crucial role of injector thermal management in improving methanol-fueled engine performance during low-temperature operation.
Lee, Seungwon, Kim, Hyunsoo, Bae, Sumin, Hwang, Joonsik, Bae, Choongsik
The Effects of Ethanol on Combustion in a Super-Lean-Burn Engine2026-01-03034/7/2026
To mitigate global warming, many countries are working toward carbon neutrality. Reducing CO₂ emissions from vehicles requires electrification technologies in hybrid and plug-in hybrid electric vehicles (HEVs, PHEVs) and improving thermal efficiency of internal combustion engines (ICEs). Lean-burn combustion is one approach to improving ICE thermal efficiency. Biofuels and synthetic fuels can also reduce CO₂ emissions in existing vehicles. Ethanol, a bio-derived fuel, is widely used in varying contents worldwide, and its further utilization is anticipated. This study examines the effects of ethanol blending on emissions, thermal efficiency, knocking, and combustion speed in a super-lean-burn engine. Gasoline surrogates with varying ethanol contents were tested at an excess air ratio (λ) of 2.5. Higher ethanol content reduced nitrogen oxides (NOx) emissions due to lower adiabatic flame temperature. Total hydrocarbon (THC) emissions measured by a Flame Ionization Detector (FID) showed a decreasing trend; however, after correction for low sensitivity to ethanol and aldehydes, no significant differences were observed. Thermal efficiency increased with ethanol content, due to reduced cooling losses. Knocking was mitigated by the higher Research Octane Number (RON) from ethanol blending; however, the extent was smaller than in the production engine operating at λ = 1. This mechanism was examined through ignition delay calculations. At λ = 2.5 and in-cylinder pressures above 9 MPa, the 50–90% combustion duration was prolonged, attributable to suppressed ethyl radical formation under lean conditions and a greater influence of the reaction in which methyl radicals consume hydrogen atoms to produce methane under high-pressure conditions.
Sugata, Kenji, Matsubara, Naoyoshi, Yamada, Ryota, Kitano, Koji
Combustion and Emission Characteristics of Biodiesel and Renewable Diesel in a 4-Stroke Locomotive Engine2026-01-03154/7/2026
Rail transportation in North America consumes over 4 billion gallons of diesel fuel [1]. This is raising energy security and supply chain resilience concerns. Adopting renewable or alternative fuels is a practical approach to reduce petroleum dependence and improve supply security. The objective of this paper is to investigate the combustion and emission characteristics of biodiesel and renewable diesel as drop-in fuels without engine modification. In this study, a single-cylinder, four-stroke locomotive engine was employed to investigate the combustion and emissions characteristics of four fuels: conventional diesel No. 2, plant-based biodiesel, animal-based biodiesel, and renewable diesel. The experimental campaign was carried out under both part-load and full-load operating conditions, with injection duration adjusted to achieve the targeted engine load and speed. Results indicate that both biodiesel fuels and renewable diesel deliver comparable peak in-cylinder pressure and brake thermal. efficiency relative to No. 2 diesel, demonstrating their possible use as drop-in fuels. Reductions in smoke emissions were observed for both biodiesels and renewable diesel fuels. However, plant-based and animal-based biodiesels both showed increases in NOx emissions under part-load conditions. At full load, elevated exhaust gas recirculation (EGR) ratios suppressed NOx formation across fuels, limiting assessment of biodiesel-specific NOx effects. Among the fuels tested, renewable diesel provided an additional advantage: reduced CO₂ emissions compared to both biodiesels. This study suggests that renewable diesel is a promising option for rail applications, combining operational performance comparable to petroleum diesel with reduced smoke and CO₂ emissions. Biodiesel, while effective at reducing smoke, may require further strategies to control NOx emissions.
Ewphun, Pop-Paul, Biruduganti, Munidhar, El-Hannouny, Essam, Longman, Douglas, Fu, Xiao, Subramanya, Raghavendra
Persistent Elevated Soot Emissions Induced by Clustered Stochastic Preignition Events2026-01-03144/7/2026
Stochastic Preignition (SPI) is an abnormal combustion phenomenon that can occur in spark-ignition engines particularly under high-load operation. SPI is characterized by uncontrolled initiation of combustion prior to spark discharge, an abnormal combustion process that can lead to severe knock events and significant engine damage. SPI has been associated with fuel properties, lubricant composition, and engine design and operation. In this work, a single-cylinder test engine with a dry-sump oil system was utilized to study the SPI response of E10 and E25 fuels with a range of Reid Vapor Pressure (RVP). An automated test procedure was employed, consisting of ten square-waved load profile segments, with each segment composed of 5 min of low-load operation followed by 25 min of sustained high-load operation. These tests were replicated across multiple days of testing including a lubricant triple flush between tests, and an online Fuel in Oil diagnostic measurement. Exhaust particulate emissions were continuously measured by an AVL microsoot sensor (MSS). Elevated particulate matter emissions were observed to occur concurrently with SPI events as blooms of soot. Particularly after clustered events (i.e., multiple SPI cycles occurring within 10 consecutive engine cycles), high soot emissions were observed to persist over several days of sequential operation despite daily lubricant changes, a complete warm-up procedure, and sustained low-load operation between test segments. This result implies that the particulate emissions trends may be dominated by deposit-based effects, where higher load operation is needed to alter deposition and formation processes. The observed soot blooms were also found to correspond to a reduction in the engine fueling and the fuel engine oil dilution rate despite the engine exhaust remaining at stoichiometric exhaust operation. These observations suggest that post-SPI events, pathways for lubricant migration and consumption into the combustion chamber may occur until these pathways are closed from deposit formation or ring dynamics during extended operation. These observed sooting propensity persisted with all fuels tests, but a linear correlation was observed between the summation of soot and particulate matter index (PMI) value for each fuel as well as SPI events, proving that PMI is a crucial fuel property for reducing SPI.1
Splitter, Derek, Jatana, Gurneesh, DelVescovo, Dan, Douvry-Rabjeau, Julien, Fioroni, Gina, Chapman, Elana, Salyers, John
Technical Outlook on the Potential of HVO and Biodiesel Blends for Cleaner Combustion2026-01-03164/7/2026
The increasing need to decarbonize the transport sector is accelerating the adoption of renewable and low-carbon fuels such as Hydrotreated Vegetable Oil (HVO) and biodiesel as sustainable substitutes for fossil diesel. These fuels are evaluated as drop-in solutions requiring no engine recalibration, enabling immediate GHG emission reduction in existing diesel fleets. This study experimentally investigates the combustion, performance, and emission characteristics of a turbocharged common-rail two-cylinder diesel engine (Kohler LWD 442 CRS) operated with conventional fossil Diesel, pure HVO (Hydrotreated Vegetable Oil), and an HVOB20 blend (80% HVO and 20% biodiesel produced from waste cooking oil and animal fats). Tests were carried out under steady-state conditions at the DIIEM Engine Laboratory of Roma Tre University. The analysis focused on in-cylinder pressure evolution, brake power, brake specific fuel consumption (BSFC), and both regulated and unregulated emissions. Regulated species include carbon monoxide (CO), nitrogen oxides (NOₓ) and particulate number concentration (PNC > 23 nm, PMP-compliant), while unregulated emissions cover non-methane hydrocarbons (NMHC), formaldehyde (HCHO), nitrous oxide (N₂O). CO and NMHC are key indicators of incomplete combustion: CO results from partial oxidation of carbon during fuel burning, and NMHC represents the fraction of unburned hydrocarbons excluding methane. Both pollutants decreased markedly with renewable fuels, indicating a more complete oxidation process promoted by HVO’s paraffinic composition and FAME’s oxygenated nature. Experimental results show that HVO and HVOB20 slightly increase brake torque and reduce BSFC compared with fossil diesel, despite their lower density and heating value. Combustion remained stable across all operating conditions, with negligible variations in ignition delay and pressure rise rate. NOₓ emissions were comparable or marginally higher at medium engine speeds, likely due to faster ignition and elevated combustion temperatures. Unregulated species such as HCHO and N₂O decreased or remained negligible with increasing renewable content, while PNC and count mean diameter (CMD) were significantly reduced, confirming cleaner combustion and reduced soot formation. Overall, both HVO and HVOB20 demonstrated improved combustion efficiency and emission performance while ensuring full engine operability without calibration adjustments. These findings confirm the technical viability of renewable diesel fuels as immediate, drop-in solutions for reducing GHG emissions.
Zaccai, Martina, Chiavola, Ornella, Palmieri, Fulvio, Verdoliva, Francesco
Achieving Euro 7 WHSC NOx Emission Targets from a Spark Ignited Engine Using Methanol-Hydrogen Co-Fuelling2026-01-03214/7/2026
E-methanol is increasingly seen as a promising clean fuel because its chemical makeup is close to fossil fuels, making it easier to use in existing engines. It offers a carbon-neutral option to help reduce greenhouse gases in sectors where cutting emissions is especially difficult, such as transportation. However, while e-methanol avoids adding new carbon dioxide, burning it in internal combustion engines still releases harmful gases like oxides of nitrogen (NOx) and other toxic by-products like formaldehyde and formic acid that damage both health and the environment. This report explores a new strategy that combines methanol with hydrogen to run engines under “ultra-lean” conditions and its impact on emissions, performance and efficiency. Experiments were carried out on a single-cylinder spark ignition engine, with directly injected methanol and port fuelled injection of hydrogen. The findings show that adding about 10% hydrogen (energy basis) at low engine loads can extend the lean limit from air-fuel equivalence ratio (λ) of 1.7 to 2. This change cut NOx emissions by 99% and reduced formaldehyde emissions by 18% compared to pure methanol operation at stoichiometric. Furthermore, the NOx emissions were reduced sufficiently that engine could operate within Euro 7 World Harmonic Stationary Cycle (WHSC) limits.
Ambalakatte, Ajith, Geng, Sikai, Cairns, Alasdair, Varaei, Amirata, Harrington, Anthony, Hall, Jonathan, Bassett, Mike, Cracknell, Roger
Challenges to Ranking Diesel Fuels for NO x Emissions Using a Constant-Volume Combustion Chamber2026-01-03484/7/2026
The market is witnessing an unprecedented proliferation of low-emission fuel components. To effectively evaluate the suitability of these novel fuels for engine applications, fuel blenders and original equipment manufacturers require rapid and reliable assessment methodologies. Traditionally, such evaluations rely on comprehensive engine testing, which, while thorough, is both time-intensive and costly. In response to the growing diversity of emerging fuel options, this work aims to establish a streamlined screening approach capable of effectively replicating the outcomes of full-scale engine testing. We examined the use of a constant volume combustion chamber for the measurement of fuel effects on NOx emissions, with the goal of developing a method to rapidly screen or rank fuels in a small - volume experiment. A small amount of fuel was injected into air at 650°C and 20 bar, where it ignited and burned. The chamber was sampled post-combustion using a chemiluminescence NOx analyzer. Extensive sampling method development was required to obtain repeatable results. Seven hydrocarbon fuels and two biodiesel fuels were tested, all of which have shown difference in NOx emissions in past engine studies. When using a single injection event to deliver the same amount of fuel energy, the test method could not clearly demonstrate the difference in NOx emissions between the hydrocarbon fuels as reported in engine combustion studies. Heat release rate analysis suggested this was caused by large differences in ignition delay and premixed burn fraction for the fuels tested. To improve this, a dual-injection strategy was used. It included a small “pilot” injection followed by a main injection, timed based on each fuel’s ignition delay to coincide with the pilot heat release. This strategy helped reduce differences in heat release caused by how quickly each fuel ignites. For hydrocarbon fuels, this approach revealed the expected relationship between NOx emissions and fuel type. Two soy biodiesel samples did not show higher NOx as observed in engine studies. This suggests that the current test method may not fully reflect engine conditions where biodiesel tends to produce more NOx. Further improvements in test method and setup are recommended to better align constant volume chamber conditions with engine conditions under which biodiesel shows increased NOx emissions.
Luecke, Jon, Rahimi, Mohammad, Mohamed, Samah, Naser, Nimal, Chausalkar, Abhijeet, McCormick, Robert
Challenges of Mixture Formation in Methanol Port Fuel Injection Engines2026-01-03374/7/2026
Port fuel injection (PFI) is an attractive strategy for methanol adoption in both spark-ignition and dual-fuel compression-ignition engines due to its lower cost and simpler hardware compared to direct-injection. However, methanol PFI mixture formation can be challenging due to methanol’s high heat of vaporization, low volatility at cold conditions and high tendency to wall wetting. Understanding and addressing these challenges is critical to ensure robust engine operation. In this study, the effects of injector geometry, coolant temperature, intake temperature and fueling rate on mixture formation of methanol PFI have been investigated for anhydrous methanol and for a blend of 90%vol methanol plus 10%vol water in an optical engine. Mie scattering and infrared imaging were applied to assess the liquid and vapor methanol distribution in the cylinder. For a high-flow injector compatible with methanol, significant amounts of liquid were detected in the cylinder at all conditions tested, leading to poor mixing and high fuel stratification during the compression stroke. This effect was mitigated by using a multi-hole injector that promoted better atomization, indicating that high atomization is preferred over high flow for methanol PFI. The probability of detecting liquid in the cylinder decreased as the coolant temperature or the intake temperature increased or if the fueling rate decreased, with coolant temperature being the dominant parameter to control methanol vaporization. Liquid probability increased with water addition mainly because of the high heat capacity of water. Liquid methanol accumulated in the intake port, decreasing the effective engine intake temperature and limiting fuel vaporization. This accumulation led to a delay of the system response to changes in the PFI settings, with injected fuel requiring one cycle to reach the cylinder and additional 50 cycles required to completely flush the fuel accumulated in the port. Finally, the operating envelope for liquid-free operation was defined.
Lee, Sanguk, Narayanan, Abhinandhan
Impact of Hydrogen on Methane and Pollutant Emissions over Three-Way Catalysts with Natural Gas–Hydrogen Blends2026-01-03574/7/2026
Blending natural gas (NG) with hydrogen (H₂) can improve combustion and engine performance while potentially facilitating the catalytic conversion of methane and other pollutants, resulting in cleaner tailpipe emissions. This study evaluates the impact of H2 on the conversion of methane, CO, and NOx emissions on a commercial three-way catalyst (TWC) in a flow reactor using synthetic gas mixtures that simulate stoichiometric engine exhausts with NG or NG+H₂ combustion. The work examines whether, and how, the additional amount of H₂ in the exhaust stream affects the conversion efficiency of methane and other pollutants. Experiments were conducted with both degreened and aged catalysts under controlled conditions, systematically varying temperature, the air-to-fuel equivalence ratio (λ), and λ modulation. Test conditions covered λ values from 0.996 to 1.000 to represent nominally stoichiometric engine operation with different λ modulation amplitudes, as well as a range of temperatures to inform control strategies for effective CH₄, CO, and NOₓ reduction. Overall, the results show that hydrogen addition significantly improves the conversion efficiency of CH₄ and NOₓ, particularly at temperatures below 500 °C. More significantly, this study highlights that exhaust gas composition, operating temperature, λ management, and the oxygen storage capacity of the TWC all play major roles in affecting the tailpipe emissions from NG and NG+H₂ combustion.
Prikhodko, Vitaly, Wang, Min, Park, Yeonshil, Chen, Hai-Ying, Pihl, Josh
Methanol Mixing Controlled Combustion Process Enabled by Methanol Dehydration to Dimethyl Ether2026-01-03224/7/2026
This work demonstrates an initial proof-of-concept approach for operating a compression ignition off-road and marine relevant engine using neat methanol. The approach utilizes mixing controlled compression ignition (MCCI) of methanol that is enabled by a homogeneous charge compression ignition (HCCI) pre-burn of premixed dimethyl ether (DME). Although two fuels are used, this work explores and evaluates the opportunity and performance to generate the premixed fuel via methanol catalytic dehydration over an alumina catalyst at engine relevant temperatures, pressures, and space velocities. Conversion purity and species output results from catalytic dehydration bench flow reactor studies were coupled with single-cylinder experiments of the characterized output species for pre-burn HCCI performance. Subsequently, methanol MCCI performance is also evaluated and compared to conventional diesel combustion. The detailed flow reactor results show that the catalytic dehydration conversion efficiency of methanol to DME is a function of system pressure, temperature, and space velocity. The engine results demonstrate that a 100% conversion of methanol to DME is not required for successful pre-burn HCCI, and the water formed during the dehydration process does not need to be removed to achieve the desired HCCI event from this pre-burn mixture. Subsequent methanol MCCI combustion results show that the level of methanol slip in the dehydration process affects the pre-burn HCCI phasing, low temperature heat release process, and magnitude of energy release, all of which can dictate the available window for direct-injection of methanol for MCCI combustion. 1
Jatana, Gurneesh, Splitter, Derek, Park, Yeonshil, Szybist, James, Svensson, Kenth, Montgomery, David
Effect of Liquidized-Gas Fluid Properties in a High-Pressure Fuel Pump2026-01-02734/7/2026
Paper considers the effects of fluid properties from liquified gases during high pressure pumping, at ranges from 200 to 1500 bar, and at speeds of 500 to 1500 rpm. Tests represent highest to date pressure ranges attained with liquified fluids such as DME. The paper examines the effects of compressibility on the pumping and resulting loading torque characteristics described over the pumping cycle as resolved by a high-fidelity sensor. Experimental tests and simulated performance based on a 1-D model are compared for Diesel and DME for a high-pressure fuel pump, piston style, featuring two plunger-barrels. Each of the pump’s plunger-barrel is inlet metered electronically, allowing the pump to run at a variable displacement and with the flexibility to deactivate one or both plungers fully. The model captures the response of the inlet metering valve and output valve lifts across speed and loads. The output check valve is subject to pressure pulsations and shows the importance to optimize its time response to stabilize it and thus provide optimal pumping. The model also captures the torque response, with contributions arising from the pressure loading, spring return force, and acceleration. Torque depends on the volume pumped, which conversely is dependent on pressure and compressibility. The volumetric efficiency is reduced as pressure increases, but the mechanical efficiency of output pressure-work over input torque remains high, between 80-90% in most of the pump operating conditions. Experimental torque measurements show close alignment with the simulations at elevated pump speeds and pressures but differences are noted at lower speeds. The deviations appear to arise from the outlet check valve stability and from the flow dynamics experienced at the pump inlet. These inlet dynamics were not properly captured in the model, but they are notable in the experimental results. Tests show significant variability in the pump pressure feed owing to the flow dynamics. Test results show this variability is reduced when the pump operates with two plunger-barrels rather than one. With one plunger-barrel the torque profile is notably cyclical, a high torque from one plunger is succeeded by a lower toque on the following plunger, while with the two plunger-barrels configuration the torque profile becomes more uniform from one plunger to the next.
de Ojeda, William, Wu, Simon (Haibao)
Effect of Pre-Chamber Geometry on Methanol Cold-Start Combustion in an SI Engine2026-01-03074/7/2026
Vehicle pollutant emissions are a major challenge in the development of internal combustion engines. To meet increasingly strict regulations, the automotive sector is exploring alternative fuels and lean-burn strategies. Methanol is gaining importance as a carbon-neutral fuel due to advances in green production technologies. Methanol, despite its potential for renewable production, faces severe limitations due to its inherent poor cold-start performance with conventional ignition systems. In this context, the present study aims to investigate the influence of pre-chamber ignition on cold-start combustion by using high-speed optical diagnostics to visualize flame propagation while simultaneously measuring in-cylinder pressure and engine performance. A major result concerns the significant cyclic variability of conventional spark ignition (SI) under cold-start conditions, which exhibits significant cyclic variability. Instead, passive pre-chamber ignition significantly enhances cold-start combustion stability, lowering CoV IMEP to below 3% at λ = 1.0 and sustaining stability under 5% even in ultra-lean conditions (λ = 1.6), where conventional SI operation fails. Flame visualization quantitatively confirms that this stability stems from distributed, multi-point ignition, which accelerates initial flame propagation by 3-4x compared to SI. These findings demonstrate that pre-chamber ignition can effectively overcome the traditional "cold-start" problem for methanol, enabling stable combustion from the first cycles. This provides an invaluable dataset for CFD model validation, as it captures a highly stable combustion process largely independent of the adverse thermal boundary conditions typical of cold start, thereby simplifying the modeling challenge.
Sementa, Paolo, Altieri, Nunzio, Tornatore, Cinzia
Effect of Key Operating Parameters on Homogenous Reactivity-Controlled Compression Ignition Concept with Renewable Fuels03-19-02-00094/1/2026
As part of the dTEC MORE project, sustainable powertrain technologies are being explored, including an alternative combustion concept tailored for engines in serial hybrid powertrains. Among the low-temperature combustion strategies, Reactivity-Controlled Compression Ignition (RCCI) is a prominent approach, offering significant reductions in NOx and soot emissions while enhancing combustion efficiency. The dual-fuel nature of RCCI enables improved control over combustion by utilizing fuels of differing reactivities. In this study, a premixed RCCI strategy was implemented using ethanol as a port-injected low-reactivity fuel and octanol as a directly injected high-reactivity fuel. The experimental work was conducted on a single-cylinder research engine with design features that are found in a gasoline passenger car application. Key combustion parameters such as the start of injection (SOI) of the high-reactivity fuel, injection pressure, intake temperature, lambda, premixed fuel ratio, and valve overlap were varied and evaluated on the engine test bench. The impact of these parameters on performance, combustion stability, and emissions was systematically analyzed. The results were benchmarked against a baseline direct-injected gasoline combustion cycle with a higher compression ratio. The comparison highlights the advantages of the premixed RCCI strategy, particularly in reducing NOx and soot emissions. Additionally, the test results also support in the future steps to model and validate the simulation models, to achieve higher efficiency and lower emissions.
Sundaram, Pravin Kumar, Grundl, Larissa Michaela, Trapp, Christian Thorsten, Tinschmann, Georg
New Graphite-Based Catalyst in Biodiesel Production04-19-02-00093/20/2026
Climate change and the depletion of fossil fuels have increased the need for renewable energy sources such as biodiesel. Biodiesel is an environmentally friendly fuel derived from various vegetable oils through a process known as transesterification. In this study, a new graphite-based heterogeneous catalyst was developed by modifying it Na2CO3, K2CO3, Al2O3 and was used for biodiesel production from linseed, cottonseed, sunflower, olive oils. Catalyst activity gradually decreased from 90.0 to 76.7% for cottonseed oil, from 93.0 to 76.0% for olive oil, from 95.0 to 77.0% for sunflower oil, and from 89.0 to 69.0% for linseed oil after the fourth operation. The fuel properties of the obtained biodiesel samples were investigated and the most favorable characteristics of cottonseed oil–based biodiesel were found to be d 4 20 = 0.8448, ν 40 = 3.3820, flash point of 93°C. Based on the X-ray broad peaks at 22.8° and 26.4°, we can note that after the four-time reaction cycle, the structure of the catalyst was destroyed to expanded and pure graphite with the loss of catalytic activity. Additionally, the influence of the amount of oleic, linoleic, linolenic, and saturated acyl groups in oil samples on exploitation properties was investigated by NMR spectroscopy.
Mamedov, Ibrahim, Mamedova, Gulben, Mamedova, Yegana
Detecting Fuel Adulteration for Otto-Cycle Vehicle Using Onboard Diagnostics Data and Supervised Machine Learning04-19-02-00082/26/2026
Fuel adulteration affects operating costs, vehicle efficiency, and air pollution. Published estimates suggest it accounts for at least 10% of global sales. The Brazilian National Petroleum Agency (ANP) reported noncompliance in about 23% of inspections in 2023, including 4.3% confirmed adulteration. Quality verification requires laboratory equipment, and sensor-based approaches are often inaccessible to end consumers. This article proposes a sensorless (software-only) method that detects water adulteration in hydrated ethanol from standard Onboard Diagnostics (OBD) data using supervised machine learning, enabling on-vehicle fuel quality monitoring without additional hardware. The proposed approach is evaluated on real-world driving data from two production vehicles with three water adulteration levels in hydrated ethanol (0.0%, 2.5%, and 5.0%), achieving 84.85%–95.85% multiclass classification accuracy. These results indicate that software-only, OBD-based monitoring can provide a practical solution for in-use fuel quality control.
Marchezan, Andre Ricardo, Giesbrecht, Mateus
CFD Simulation of Combustion and Emission Characteristics of Pure Spirulina Microalgae Biodiesel in a Single-Cylinder DI Diesel Engine2026-28-00432/12/2026
In this study, the combustion and emission characteristics of a single-cylinder direct injection (DI) diesel engine fueled with Spirulina biodiesel along with diesel blends were examined using a combined CFD and thermodynamic simulation framework. Three test fuels, including pure diesel (D100), Spirulina biodiesel blends (B20 and B40), and pure Spirulina biodiesel (B100), were analysed at 1500 rpm under full load. In the first stage, CFD simulations were performed in ANSYS Fluent, where the Discrete Phase Model (DPM) was applied to capture spray atomization and droplet evaporation, while a non-premixed combustion model coupled with the RNG k-ε turbulence model was employed to resolve in-cylinder flow and heat release dynamics. Subsequently, the Diesel-RK software was utilised to predict engine performance and exhaust emissions based on compression ratios (18.5) and injection timings. Results from the CFD analysis revealed faster atomization and reduced ignition delay for biodiesel blends compared with pure diesel, supported by enhanced cylinder pressure development. Diesel-RK simulations indicated that Spirulina biodiesel blends (B20) generally improved brake thermal efficiency at higher compression ratios while increasing brake specific fuel consumption due to their lower calorific value. Emission analysis showed consistent reductions in CO, HC, and smoke capacity with higher biodiesel content, while NOx emissions exhibited a rising trend. The findings confirm Spirulina biodiesel (B20) as a viable renewable fuel and highlight simulation-driven strategies for optimising compression ratio and injection timing in CI engines..
Kumar, B Varun
Enhancing Combustion, Performance and Emission Profiles Using Kapok Methyl Ester Blends with Hydrogen2026-28-00582/12/2026
This study investigates the potential of using a dual green alternative fuel combination, the one is hydrogen fuel and another one is biodiesel for enhancing the Performance, combustion and emission profile of a compression ignition engine. The kapok oil biodiesel was blended with Diesel in proportions of 20% (K20) and 40% (K40) by volume. The hydrogen gas was supplied at a constant flow of 4 liter per minute (LPM). The experimental fuels are neat diesel D100, K20 (80% Diesel and 20 % kapok methyl ester), K40 (60% Diesel + 40 % Kapok methyl ester), K20 + H4L (K20 with 4 LPM hydrogen) and K40+H4L (K40 with 4 LPM hydrogen). These test blends are investigated in a single cylinder direct injection CI engine under 0% to 100% load conditions at a fixed speed of 1500 rpm combustion, and emissions characteristic were evaluated and compared with base fuel. The outcomes indicated that the use of B20 and B40 blends without hydrogen led to reduced BTE because of their lower cetane number and calorific value. Additionally, higher viscosity of the blends resulted in increased BFSC. However, the introduction of hydrogen and the K20H fuel blend demonstrated notable emission improvements compared to conventional diesel, achieving reductions of 9–11% in unburned hydrocarbons, 5.3% in carbon monoxide, and approximately 8% in nitrogen oxides (NOₓ). These findings highlight the potential of K20H as a cleaner alternative fuel.
Anbarasan, B, M, Kumaresan, Balamurugan, S, Rajesh, Munnusamy
Flow-Based Corrosion Analysis of NBR-PVC Fuel Hoses in Ethanol-Gasoline Blends2026-28-00792/12/2026
The integration of ethanol into gasoline presents compatibility challenges for automotive fuel-system materials. In this study, the degradation of NBR-PVC fuel hoses exposed to ethanol-gasoline blends (E30, E50, E70, and E100) was investigated under dynamic flow conditions. A custom-designed test rig simulates real-time fuel circulation for 1,200 h. FESEM, ATR-FTIR, and elemental mapping analyses revealed ethanol-induced degradation, including dehydrochlorination, plasticizer leaching, and filler detachment. Among the blends, E30 exhibited the least material degradation, whereas E100 showed significant surface damage and chemical alteration. This study recommends multilayered fuel hose structures with ethanol-resistant inner linings for enhanced durability.
PC, Murugan, L S, Adhitya, G, Arun Prasad, W, Beno Wincy, T, Karthi
Rolls-Royce pursues pure methanol for marine engines26TOFHP02_052/1/2026
Rolls-Royce has successfully tested the world's first high-speed marine engine powered exclusively by methanol on its test bench in Friedrichshafen, Germany. The company began this engine-development journey six years ago when it gathered experts to determine what the future fuel of the maritime industry should be, according to Denise Kurtulus, senior vice president of global marine at Rolls-Royce. “For us, it's clear. It's methanol,” she said. Rolls-Royce worked with industry partners as part of the joint project meOHmare, which is funded by the German Federal Ministry for Economic Affairs and Energy. Injection system specialist Woodward L'Orange and the WTZ Roßlau technology and research center contributed their expertise. Their goal was to not only develop a comprehensive concept for a CO2-neutral marine engine based on green methanol, but also to run it on the test bench by the end of 2025.
Gehm, Ryan
Comparative Journey Towards Sustainable Energy: CNG and Bio-Diesel Fuels in India2026-26-01161/16/2026
India being highly populated and developing country, the demand for various alternative fuel is increasing drastically. It is driven by the need to reduce dependency on traditional fossil fuels & reduce impact on environmental issues like Greenhouse gas, emissions & pollution. The potential options, CNG (Compressed Natural Gas) & Biodiesel, are becoming increasingly popular and important. Biodiesel, a renewable fuel which is produced from waste materials & crops which grown repeatedly & easily available while CNG is more sustainable than diesel as natural gas is a cleaner-burning fossil fuel in comparison to coal or oil. This paper will focus on comparison between basic properties of Diesel, CNG & Biodiesel. In this study will also focus on survey of various Government initiatives, policies & infrastructural development which are evolving to encourage the usage of CNG & Biodiesel. These fuels are emerging as promising alternative contenders to traditional diesel. It has the potential to reduce carbon footprints, making them environment friendly & more sustainable energy options. This survey also summaries the industry motivation from govt initiatives to promote the aim of cleaner transportation & its transition towards future sustainable energy. This study presents a comparative journey of CNG & Biodiesel in India. Key parameters like fuel properties, feedstocks and its availability, storage and handling, product integration, emissions and endurance performance assessments, customer acceptability etc. are considered for understanding these fuels in a better way. Also, it will highlight the key bottlenecks, technical challenges & the obstacles hindering the widespread adoption of Biodiesel as compared to CNG. The paper also elaborates the challenges on sustainability of biodiesel and CNG fuels and the futuristic opportunities in carbon neutral fuels like H2. The paper concludes with the comparative study of CNG & Biodiesel on various aspects from ideation to execution.
Bondada, Nandita, Baruah, Labanya, Mokhadkar, Rahul
Correlation of Particulate Matter Species on Gasoline Direct Injection (GDI) Vehicle with Ethanol Blended Gasoline: Real Drive Emissions based Portable Emission Measurement System2026-26-02161/16/2026
On the way to net zero emissions and to cut the oil import bills, NITI Aayog, Government of India and Ministry of Petroleum & Natural Gas (MoP&NG) has rolled out roadmap for ethanol blending in India during 2020-2025. Also, National Policy on Biofuels – 2018, provides an indicative target of 20% ethanol blending under the Ethanol Blended Petrol (EBP) Programme by 2030. Considering these Government’s initiatives current studies were performed on BSVI compliant gasoline direct injection vehicle on RDE compliant route (Route formulated by Indian Oil R&D Centre) with different ethanol blended gasoline fuel formulations i.e., E0 (Neat Gasoline), E10 (10% Ethanol in gasoline) & E20 (20% Ethanol in gasoline). The study aims to determine the compliance of Conformity Factor (C.F.) for ethanol blended gasoline fuel on Direct Injection gasoline engine. The conformity factors were calculated in each case for CO, NOx & PN using moving window average evaluation method. For reference CO2 characteristics curve, CO2 values were measured over Modified Indian Driving Cycle (MIDC) on chassis dynamometer. The study suggests that the use of oxygenated fuel formulations (E10 & E20) impacts tail pipe emissions in a greater way and without any change in the hardware of after treatment devices of the vehicle tail pipe emissions can be reduced. Paper presents RDE as well laboratory mass emissions data collected. However, all the emission values are well below the typical BSVI/Euro6d limits and the C.F for NOx is also below than stated limit of BS_2.0 IRDE (Indian Real Driving Emissions).
Kant, Chander, Arora, Ajay, Saroj, Shyamsher, Kumar, Prashant, Sithananthan, M, Chakradhar, Dr Maya, Kalita, Mrinmoy
Effect of E20 Fuel on Vehicle Performance Parameters of 694CC Gasoline Engine for Commercial Vehicle Application2026-26-05651/16/2026
In alignment with its carbon reduction commitments, India is transitioning towards higher ethanol-blended fuels, with E20 set for nationwide implementation by 2025. Ethanol is a renewable, domestically produced biofuel produced through fermentation of biomass such as sugarcane, corn. It possesses a higher octane rating and oxygen content compared to conventional gasoline, making it a favorable additive for improving engine performance and reducing emissions. This study investigates the impact of E20 fuel on performance parameters of a 694 cc MPFI , water-cooled, twin-cylinder gasoline engine. For deriving maximum benefits of increased Octane rating of E20, compression ratio was increased to 12.5:1. Experimental analysis was conducted to assess the changes in combustion behavior, brake specific fuel consumption (BSFC), torque output, engine out emissions and thermal efficiency when operating on E20 compared to baseline gasoline (E10). Base results indicate that E20 promotes more efficient combustion, owing to its higher laminar flame speed and elevated oxygen content, leading to a 3–4% improvement in low-end torque across real-world operating speed ranges. Conversely, on-road evaluations reveal a 3–4% fuel economy penalty with E20 relative to E10. Recovering E10-comparable fuel efficiency with E20 necessitates comprehensive engine calibration optimization, supported by targeted hardware modifications. Additionally, the high octane rating of ethanol reduces knock propensity, enabling the adoption of more aggressive ignition timing and higher compression ratios without compromising engine durability. Thermal benefits are also taken into consideration, with a reduction in peak mid-catalyst temperatures by approximately 30–40°C, this enables stoichiometric operation throughout operating range without any enrichment. These improvements suggest that engines calibrated specifically for E20 can be benefited through fuel’s inherent properties to achieve higher thermal efficiency and lower tailpipe emissions. In conclusion, the incorporation of E20 fuel in internal combustion engines shows notable advancements in engine performance and efficiency.
Kulkarni, Deepak, Malekar, Hemant A, Thonge, Ravindra, Kanchan, Shubham
Performance Optimization of 2 Cylinder Flex Fuel Engine for Small Commercial Vehicle – A STEP TOWARDS SUSTAINABILITY2026-26-01191/16/2026
Increasing ethanol blending in gasoline is significant from both financial (reducing dependency on crude oil) and sustainability (overall CO2 reduction) points of view. Flex Fuel is an ethanol-gasoline blend containing ethanol ranging from 20% to 85%. Flex Fuel emerges as an exceptionally advantageous solution, adeptly addressing the shortcomings associated with both gasoline and ethanol. Performance optimization of Flex Fuel is a major challenge as fuel properties like knocking tendency, calorific value, vapour pressure, latent heat, and stoichiometric air-fuel ratio change with varying ethanol content. This paper elaborates on the experimental results of trials conducted for optimizing engine performance with Flex Fuel for a 2-cylinder engine used in a small commercial vehicle. To derive maximum benefit from the higher octane rating of E85, the compression ratio is increased, while ignition timing is optimized to avoid knocking with E20 fuel. For intermediate blends, ignition timing is suitably interpolated. Fuel injection pressure is increased to address the higher fuel flow requirement, and a fuel heater is added to address cold starts with E85 fuel. Ethanol content detection is done through software, and by suitable interpolation, fuelling and ignition timing are optimized for the entire range of Flex Fuel in a single calibration file. Engine performance with E20 & E93 fuel is optimized considering all mechanical and thermal limits of the engine through various iterations. The experimental results are analysed using the first principle method.
Kulkarni, Deepak, Malekar, Hemant A, Upadhyay, Rajdip, Katkar, Santosh, Undre, Shrikant
Development of Flex Fuel Engine for Indian Market2026-26-01171/16/2026
This paper presents the methodology and outcomes of modifying a 1.2L naturally aspirated (NA) engine to enable flex-fuel compatibility, targeting optimal performance with ethanol blends ranging from E20 to E100. Ethanol is being increasingly promoted due to its potential to reduce greenhouse gas emissions and to provide an additional source of income for farmers. As per the road map for Ethanol blending released by Govt. of India, there has been continuous increase in blending of ethanol in gasoline. An initial target of 20% ethanol blending in gasoline by April 2025 has already been achieved. This work is in alignment with the broader push for development of flex-fuel vehicles, which necessitates engine adaptations capable of operating on varying ethanol blends. The primary objective was to upgrade the engine, which can give optimum performance with both lower range of ethanol blends starting from E20 as per IS 17021:2018 standard till higher blends of up to E100 as per IS 17821:2022. The engine upgrade included several key modifications such as material upgradation of components directly coming in contact with fuel for ethanol resistance, optimization of the compression ratio, introduction of heated fuel rail system for cold start and redesign of intake camshaft to ensure compatibility and performance with ethanol-blended fuels. Additionally, the engine management system (EMS) was recalibrated with dedicated maps tailored to various ethanol blend levels, enabling efficient and reliable operation across a wide range of fuel compositions
Tyagarajan, Sethuramalingam, Pise, Chetan, Kavekar, Pratap, Agarwal, Nishant Kumar
Material Compatibility Studies of Ethanol Blended Diesel2026-26-01291/16/2026
The Government of India has mandated biofuel blending in automotive fuels to reduce crude oil imports and support the national economy. As part of this initiative, Oil Marketing Companies (OMCs) have begun nationwide blending of E20 fuel (20% ethanol in petrol). Ethanol supply is expected to exceed demand by the end of 2025 due to initiatives like the Pradhan Mantri JI-VAN Yojana. Alternative applications for ethanol are being explored; one promising approach is its use as a co-blend with diesel fuel (ED blends). However, ethanol’s low cetane number and poor lubricity pose challenges for direct use in diesel engines without modifications. ED blends demonstrated reduced emissions while maintaining performance comparable to conventional diesel. To further address concerns related to materials compatibility of ED blends with fuel system components, particularly plastomers that may impact engine durability, a detailed study was conducted using elastomers such as FVMQ, FKM, HNBR, and NBR in accordance with the SAE J1748. Test specimens were immersed in ED blends and conventional diesel at 55°C for 1008 hours. Key physical and mechanical properties were measured before and after the immersion tests. The results revealed that FVMQ, FKM and HNBR demonstrated comparable durability when exposed to ED blends vis-à-vis diesel, whereas NBR performed better only in conventional diesel. SEM analysis of the specimens showed significate surface degradation in NBR, supporting the mechanical test results. Although ED blends exhibited changes in fuel properties such as flash point and water content, the blends remained stable under ambient storage conditions.
Johnpeter, Justin P, Chakrahari, Kiran, Chakradhar, Maya, Arora, Ajay, Prakash, Shanti, Pokhriyal, Naveen Kumar
For CNG and FFV Fuel Application Exhaust Valve Redesign and Robustness Improvement to Combat Abnormal Valve Guide and Seat Wear2026-26-01251/16/2026
Today, passenger car makers around the world are striving to meet the increasing demand for fuel economy, high performance, and silent engines. Corporate Average Fuel Economy (CAFE) regulations implemented in India to improve the fuel efficiency of a manufacturer's fleet of vehicles. CAFE goal is to reduce fuel consumption and, by extension, the emissions that contribute to climate change. CNG (Compressed Natural Gas) engines offer several advantages that help manufacturers meet and exceed these standards. The demand for CNG vehicles has surged exponentially in recent years, CNG engine better Fuel efficiency and advantage in CAFÉ norms make good case for OEM & Customer to use more CNG vehicle. CNG is dry fuel compared to gasoline. These dry fuels lack lubricating properties, unlike conventional fuels like petrol, diesel and biofuels, which are wet and liquid. Consequently, the operations and failures associated with these fuels differ. The materials and designs of engine parts, such as fuel lines, ECU, exhaust valves, and cylinder heads, vary depending on the fuel used. In CNG engine most challenging issue is leakage at Valve seat and Valve face interface causing unstable combustion and power drop. This study discusses the countermeasures adopted to address the high valve face, Valve guide and valve seat wear in cylinder heads and engine valves. The investigation focuses on material, design, and manufacturing process improvements specially for Exhaust valve, supported by part-level and vehicle-level validation and testing for CNG exhaust valves and cylinder heads.
Poonia, Sanjay, Kumar, Chandan, Sharma, Shailender, Khan, Prasenjit, Bhat, Anoop, P, Prasath, Neb, Ashish
Flex-Fuel Technology for India: Challenges, Opportunities, and Compliance with Emerging Emission Norms2026-26-01091/16/2026
The adoption of flex-fuel vehicles (FFVs) in India presents a significant opportunity to reduce dependence on fossil fuels, lower greenhouse gas emissions, and ensure compliance with the country’s evolving emission norms. This paper explores the key aspects of flex-fuel technology in the context of Indian four-wheeler regulations, particularly Bharat Stage VI and potential future emission norms. The study begins with an overview of flex-fuel technology, detailing its advantages and associated challenges. A critical focus is placed on blend identification techniques, which play a vital role in optimizing combustion efficiency and ensuring seamless transitions between different ethanol-gasoline blends. Furthermore, the impact of ethanol blending on various fuel properties is examined, including changes in energy content, latent heat of vaporization, octane number rating, and stoichiometric air-fuel ratio. These factors significantly influence engine performance and emission characteristics, highlighting both challenges and opportunities in meeting emission targets. Finally, the study presents key conclusions on the viability of flex-fuel adoption in India. By addressing the challenges and opportunities associated with the technology, this paper attempts to provide insights for optimizing its implementation in the evolving automotive landscape.
Balasubramanian, Karthick, KR, Prabhakar, Kallahallii Somu, Santhosh Kumar
Improving Late Pilot Injection Strategy in Dual-Fuel Diesel/Methane Engines through Supercharging and Hydrogen Enrichment03-18-08-004912/24/2025
In this study, a novel dual-fuel combustion strategy is investigated, employing late pilot injection in diesel–methane engines to improve performance and reduce emissions. The engine was first tested with conventional diesel and methane, exploring a wide range of pilot injection timings, injection pressures, and intake boost pressures. Subsequently, experiments were repeated using a methane/hydrogen blend to assess the influence of hydrogen addition. Results show that, when using only methane, delayed pilot injections have minimal effects on engine performance. In naturally aspirated operation, unburned hydrocarbons and carbon monoxide are reduced, while in supercharged conditions, emissions increase; however, they remain within acceptable limits. Nitrogen oxides and particulate matter reach their lowest levels with delayed injection. Introducing hydrogen reduces engine performance and hydrocarbons and carbon monoxide emissions; notably, it suppresses the typical nitrogen oxides increase associated with hydrogen, while also lowering particulate matter. These findings demonstrate that combining late pilot injections with hydrogen addition and supercharging is a promising strategy for improving dual-fuel engine efficiency and emissions, offering a potential pathway toward cleaner combustion.
Carlucci, Antonio Paolo, Strafella, Luciano, Ficarella, Antonio
Analysis of Light Duty Vehicle Particulate Matter Emissions Using Scanning Electron Microscopy2025-36-007412/18/2025
Particulate matter (PM), mainly its finer fraction, is among the main atmospheric pollutants present in an urban environment. The relationship between the increase in the concentration of this pollutant and the harm to human health is well established. The main sources of particulate matter in urban areas are mobile sources, which include the exhaust emission from light duty vehicles. This work measured the emission of PM in three light duty passenger vehicles, characterizing it in terms of emitted mass in one “flex” vehicle with port fuel (indirect) injection (PFI), using ethanol and gasohol (mixture of 22% anhydrous ethanol and 78% gasoline, by volume), in another “flex” vehicle with direct fuel injection (GDI), and in a diesel vehicle. In addition to mass measurement, images of the filters used in PM sampling were produced using scanning electron microscopy. The processing of these images made it possible to determine the average PM size, as well as establish a particle size distribution for each vehicle and test fuel. With the same instrument, the presence of some chemical elements present in the sample could be determined, through Energy Dispersive Spectroscopy (EDS) analysis.
Borsari, Vanderlei, Neto, Edson Elpídio, de Abrantes, Rui
Numerical Simulation of Additized Ethanol: Impact of Engine Parameters on Combustion, Performance and Emissions2025-36-025012/18/2025
One alternative to fossil fuels is the use of bioethanol in internal combustion engines. However, the application of this renewable fuel in compression-ignition engines is limited due to its low cetane number. This barrier, however, can be overcome by using additives that enhance this property. Consequently, additized ethanol emerges as a promising option with significant potential for decarbonization and improved combustion efficiency. In this context, the present study numerically investigated, using the CONVERGE CFD software, the use of additized ethanol in a compression-ignition internal combustion engine used in marine transportation. As a comparative baseline for each investigated setup, cases involving conventional diesel fuel were also analyzed numerically. The reaction mechanisms used for modeling the combustion of both additized ethanol and conventional diesel were validated against experimental data available in the literature. Di-tert-butyl peroxide (DTBP) was the studied cetane improver used in this study, blended with ethanol at weight fractions equal to 0%, 5% and 10%. In addition to the additive content in ethanol, the study also evaluated, through a sensitivity analysis, the impact of fuel injection strategies, including variations in injection timing (from 6 to 0 degrees before top dead center) and engine load levels (25%, 50%, 75%, and 100%). Key combustion, performance, and emission parameters were analyzed, including ignition delay, heat release rate, thermal and combustion efficiency, and emissions of CO₂, CO, NOX, CH4 and CO2eq. The results indicate that additized ethanol is a viable fuel for compression-ignition engines.
Assis, Guilherme, Sánchez, Fernando Zegarra, Pradelle, Renata Nohra Chaar, Braga, Sergio Leal, Ticona, Epifanio Mamani, Souza Junior, Jorge, Pradelle, Florian
Calculation of Greenhouse Gas Emissions in CO 2 Equivalent per Hectare of Sugarcane Cultivated for Brazilian Ethanol Production2025-36-019112/18/2025
This study aims to quantify, through Monte Carlo simulation (100,000 iterations), the greenhouse gas (GHG) emissions associated with the complete production cycle of ethanol from sugarcane in Brazil, expressed in kg CO2eq/ha, and to project these emissions over a 20-year horizon. To achieve this, the production cycle was segmented into distinct stages - land use change, soil management and preparation, fertilization, harvesting and straw management, soil carbon sequestration, and industrial processing - and the parameters for each stage were defined based on recent. Three representative scenarios were considered: Worst-case (unsustainable practices involving conversion of native vegetation, high fertilizer dosages, and complete burning of the straw), Typical (conventional practices, with conversion of degraded pastures and sustainable management), and Ideal (best practices, characterized by reduced input dosages, the use of nitrification inhibitors, and high straw retention). The results indicate that, under sustainable practices, ethanol exhibits a significantly lower carbon footprint compared to gasoline, whose typical emissions range between 2.8 and 3.0 kg CO2eq/L. These findings reinforce the potential of Brazilian ethanol to contribute to GHG emission reductions and underscore the importance of adopting sustainable agricultural practices.
Assis, Marcelo Suman Silva, Paula Araújo, Gabriel Heleno de, Baeta, José Guilherme Coelho, Abreu, Pedro Blaso Barbosa de, Filho, Fernando Antonio Rodrigues
Effect of Ultra-High Fuel Injection Pressure on Combustion Characteristics, Engine Performance and Pollutant Emissions of a Multi-Cylinder Engine2025-36-021212/18/2025
The concern about CO2 emissions from commercial vehicles powered with internal combustion engines has been motivating research and development projects to reduce the transportation sector carbon footprint. One of the promising alternatives is the use of biofuels associated with high-efficient internal combustion engines, taking advantage of the current infrastructure of car manufacturers and automotive suppliers, as well as of the potential growth in biofuel production. With the stringent emissions regulations, the use of downsized SI engines for passenger cars has driven the adoption of direct injection technology, enabling the use of different fuel injection strategies such as stratified mixtures and multiple injection events, as well as the increase of the compression ratio as a way to improve engine thermal efficiency. This path also led to a gradual increase in injection pressure, aiming to improve spray formation and reduce the formation of particulate matter. In this sense, the implementation of such technology on the Brazilian flex-fuel engine represents an important path to the transport sector decarbonization. However, the use of hydrous ethanol and gasoline-anhydrous ethanol blends on direct injection systems still demands fundamental research to fully understand the potential benefits and drawbacks of higher fuel injection pressures. Within this framework, this work aims to further understand the effect of using ultra-high fuel injection pressures (up to 1000 bar) on engine performance and pollutant emissions of a multi-cylinder prototype engine. Experimental tests with three different injection pressures confirmed the HC and soot emission reduction, as well as improvement on the engine brake thermal efficiency both when fueled with hydrous ethanol and Brazilian gasohol (blend of 27% anhydrous ethanol in gasoline). Due to the lack of dedicated hardware to pressurize and inject ethanol at ultra-high pressures, the durability of the injection components was a major concern during the experimental campaign.
Antolini, Jácson, Zabeu, Clayton Barcelos, Pires, Gustavo Cassares, Polizio, Yuri
Experimental Investigation of Additive Formulations for Ethanol Use in Compression Ignition Engines Using a Rapid Compression Machine2025-36-018512/18/2025
The transition to renewable fuels is critical to reduce greenhouse gas emissions and achieve carbon neutrality in the transportation sector. Ethanol has emerged as a promising biofuel for compression ignition (CI) engines due to its renewability and low-carbon profile. However, its low cetane number, high latent heat of vaporization, poor lubricity, and corrosive properties severely limit its auto-ignition capability and durable operation under conventional CI conditions. Building upon previous work using a Rapid Compression Machine (RCM) to assess ignition improvers for ethanol, this study explores a broader range of fuel formulations to enhance ethanol-based combustion. A total of nine blends were prepared, consisting predominantly of hydrated ethanol (50-80% by volume), combined with 5-25% biodiesel and up to 5% of a commercial ignition improvers. The biodiesel component acted both as a co-solvent and as a combustion stabilizer, particularly under cold-start conditions. Tests were carried out under both hot and cold-start conditions, across compression ratios ranging from 25:1 down to the ignition failure limit. To ensure equal injected energy input, injected fuel mass was adjusted based on the Lower Heating Value (LHV) of each blend. High-resolution pressure transducers and high-speed optical imaging were employed to provide direct experimental insights into the combustion process, validate thermodynamic trends, and support comparative assessments of ignition behavior across different blends and compression ratios to evaluate key combustion parameters. The results indicate that blends enriched with both biodiesel and ignition additives, particularly E900B50A50, E925B50A25, and E925B25A50, significantly improved auto-ignition performance, enabling complete and stable combustion under compression ratios higher than 23. Uniform flame front propagation was observed across all injector nozzles, indicating complete combustion and effective fuel–air mixing, which are essential for maximizing thermal efficiency and minimizing unburned emissions in CI engine operation.
Bacic, Denise Amato, Sánchez, Fernando Zegarra, Ticona, Epifanio Mamani, Pradelle, Renata Nohra Chaar, Santos Coelho, Lucas dos, Mota, Crislane Almeida Pereira da, Pradelle, Florian
Mixing Rules for Accurate Prediction of Physicochemical Properties in Automotive Diesel-Biodiesel-Ethanol Blends2025-36-013512/18/2025
The increasing demand for reduced emissions in the automotive sector has driven research into alternative fuels, including Diesel, Biodiesel, and ethanol blends. This study aims to optimize mixing rules to predict the physicochemical properties of ternary fuel blends, essential for improving engine performance and minimizing emissions. Seven established mixing rules—Kay’s Equation, Semilogarithmic Equation, Grunberg-Nissan Equation, Modified Lederer Equation, Hu-Burns Equation, Power Law, and Polynomial Equation—were evaluated to estimate key properties such as kinematic viscosity, cetane number, cetane index, flash point, pour point, and cloud point. A comprehensive database, sourced from previous literature, included pure fuel properties and blend data for 33 to 101 cases. MATLAB was used to implement nonlinear optimization, adjusting coefficients to minimize error metrics like Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Standard Deviation (SD). The physical consistency of the correlations was verified by ensuring that estimated properties followed expected trends. The results identified the best-performing equation for each property, with the Grunberg-Nissan equation providing reliable estimates for viscosity and cetane number, and the Hu-Burns equation excelling in cetane index and cloud point. Additionally, the polynomial equation demonstrated accuracy for flash point. The optimized correlations were validated with independent experimental data, confirming their robustness and suitability for automotive fuel applications. This approach simplifies the selection of fuel compositions, contributing to cleaner fuel formulations and supporting the shift towards sustainable energy solutions.
Tirado, Carlos Andrés Abanto, Lobato, Maria Letícia Costa, Passos, Sthefany Faber, Pradelle, Renata Nohra Chaar, Pradelle, Florian
Optimization of Biogas Combustion in SI Engines Applied to the Pre-Chamber Ignition System2025-36-020912/18/2025
The diversification of the energy matrix, combined with the use of renewable and less polluting fuels in internal combustion engines, has encouraged numerous research efforts both nationally and internationally. In this context, the utilization of waste for biofuel production stands out as a promising alternative, offering a clean and economically viable energy source. Biogas is one of the most sustainable options and has been widely used in the industry. However, it presents low lower heating values (LHV) and difficulties in burning stoichiometric mixtures, which compromise engine performance, resulting in higher specific fuel consumption and lower power output compared to fossil fuels. To address this challenge, this study aimed to improve biogas combustion in internal combustion engines by investigating the application of a new pre-chamber ignition system in the combustion process and engine performance parameters. For this, experimental tests were conducted with two biofuel concentrations for evaluation: (100% CNG) and (85% CNG + 15% CO2), enriching the stoichiometric mixture and applying calibration methodologies in a single-cylinder engine adapted to operate with biogas, assessing engine performance parameters and gas emissions. The application of pre-chamber ignition showed significant improvements in energy efficiency, resulting in approximately a 12% torque gain in stoichiometric mixtures, contributing to more efficient combustion and a reduction in hydrocarbon emissions. The use of mixtures in the range of 1.0 to 1.2 led to emission reductions between 60% and 35% compared to the engine without the pre-chamber, demonstrating the pre-chamber’s ability to promote more complete combustion even in leaner mixtures. The data obtained provide valuable insights for the development and application of new technologies in biogas-powered internal combustion engines, contributing to advancements in this research area.
Siqueira, Caio Henrique Moreira, Ázara, Luiz Eduardo Martins, Ribeiro, José Vitor Puttini, Soares, Gabriel Faria, Silva, Fábio Moreira, Alvarez, Carlos Eduardo Castilla
Performance Analysis of Methanol- Ethanol Blend Fuel in a Spark-Ignition Flex-Fuel Engine2025-36-014812/18/2025
Flex-fueled vehicles (FFV) dominate the Brazilian market, accounting for over 75% of the national fleet. Ethanol fuel is widely used, primarily in the form of hydrated ethyl alcohol fuel (HEAF). Given the similar physicochemical properties of ethanol and methanol, fuel adulteration is a growing concern, often involving the addition of anhydrous ethanol, methanol, or even water to hydrated ethanol. These adulterants are visually imperceptible and can only be detected through analyses conducted by regulatory agencies using specialized instruments. However, they can significantly affect vehicle performance and accelerate engine component deterioration. The experiment was performed with a small displacement 3-cylinder port fuel injection flex-fuel engine on an engine test bench (dynamometer) and compared when fueled with ethanol and methanol. Data acquisition included combustion pressure, spark plug temperature, torque, air-fuel ratio, fuel flow, spark maps, and the overall effects of methanol adulteration on combustion. The results indicate that engines designed and calibrated to operate with hydrated ethanol exhibit different combustion behaviors when methanol is present in the fuel mixture. Methanol increases combustion pressure and temperature inside the chamber, creating a highly corrosive environment due to both the elevated temperature and the chemical properties of methanol. Fuel consumption increased when methanol was used in the engine calibrated for ethanol. The findings highlight the potential risks associated with fuel adulteration, emphasizing its impact on engine durability, vehicle fuel economy, and maintenance costs.
Mascarenhas, Giovana Rebellato, Gomes, Ederson, Cruz, Diego, Duque, Edson Luciano
Effects of Vehicle Usage on Aldehyde Emissions in Flex-Fuel PFI Engines Using Ethanol2025-36-009812/18/2025
Brazil PL8 regulation has required that manufacturers comply with new emissions levels for all of vehicle life – 0 km up to 160.000 km. On this study, tests found that results between new and used vehicles are remarkably similar except for Aldehydes on Ethanol tests. To better understand this phenomena, two main ideas were considered: first, the engine mileage needed to stabilize aldehydes emissions; and second, the main factors responsible for higher acetaldehyde values on new engines only.
Fernandes, Sarah, Borsari, Marcio, Brondani, Dhouglas
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