Browse Topic: Hydrocarbons

Items (2,995)

Identification and Quantification of PAHs in Gasoline Soot Using ASE-GC-MS/MS

2026-99-0110

7/31/2026

In the present work, a novel method that combines accelerated solvent extraction (ASE) and gas chromatography coupled with triple quadrupole tandem mass spectrometry (GC-MS/MS) was proposed to identify and quantify polycyclic aromatic hydrocarbons (PAHs) in gasoline soot. The n-hexane was employed to extract the target analytes, and the optimal extraction conditions were identified (cycle times = 3, extraction time = 30 min, extraction temperature = 120°C, and extraction pressure = 100 MPa). The extraction efficiency of six analytes was measured to assess the ASE method; the formation mechanism of partial PAHs was discussed, and the 18 PAHs in gasoline soot were studied both qualitatively and quantitatively under the optimal conditions. It was found that our new method reached a high correlation coefficient (between 0.9987 and 0.9997); the limits of quantification (LOQs) (S/N = 6) for these PAHs were between 0.003 and 0.009 ng/mL with a relative standard deviation (RSD) of 2.9–10.6%. Our method demonstrated good performance in determining the target analytes in soot samples, such as gasoline soot, some materials soot, co-combustion soot, gasoline, and materials. The PAHs differences in soot samples containing gasoline and materials soot samples were significant enough to obtain the observed discrimination. The method is an accurate and sensitive quantitative method to identify gasoline residues in soot samples of arson fire.

Liu, Shujun, Cao, Henan, Qi, Lijie, Liu, Yang, Li, Qi

Spray–Wall Interaction at Thermal Swing Coatings in SI Engines

03-19-03-0014

6/25/2026

As a contribution to the reduction of greenhouse gas emissions in the transportation sector, the indicated efficiency of SI engines can be increased via thermal swing coatings. Thereby, a decrease in greenhouse gas emissions can be achieved, although not at all operating conditions. Here, the often-observed increased hydrocarbon emission partially overcompensates the reduced wall heat losses. The main root cause is always attributed to the increased surface roughness and porosity, leading to an increased crevice volume. Further investigations were performed at a single-cylinder engine equipped with a FTIR for species analysis of hydrocarbon emissions. A comparison of direct injection and port fuel injection were performed for RON95 E10 and methanol to assess the influence of mixture preparation. 3D CFD was used to additionally investigate the in-cylinder processes. The comparison of port fuel injection and direct injection showed a significant influence on the fuel hydrocarbon emissions for the direct injection when the thermal swing coating was applied. The effect is more pronounced for methanol. For port fuel injection nearly the same or reduced fuel hydrocarbon emissions can be observed. This is mainly attributed to an increased wall film agglomeration at the piston for the thermal swing coating in case of direct injection, which can be observed in 3D CFD. Due to the low thermal effusivity of the coating, the droplet impingement leads to a notable decrease in the surface temperature. This results in lower evaporation of the fuel and a longer droplet lifetime. Consequently, a fuel wall film is still present at top dead center after ignition leading to additional hydrocarbon emissions.

Fischer, Marcus, Pischinger, Stefan

Nitrogen-Based Emissions from Ammonia Combustion in a Heavy-Duty Spark Ignition Engine

2026-37-0032

6/9/2026

Ammonia (NH3) is a carbon-free fuel with strong potential for spark-ignition (SI) engine applications. However, the engine can produce complex nitrogen-based emissions not adequately captured by conventional engine models. This study consolidated the results of experimental and numerical studies on the use of neat NH3 combustion in a heavy-duty compression-ignition engine converted to spark-ignition operation, first for a sweep of equivalence ratios (ϕ) from 0.7 to 1.0, and another from varying the energy substitution ratio of methane (CH4)– NH3 blends from neat CH4 to neat NH3 at constant ϕ = 0.8. Two 0-D two-zone SI engine models with detailed chemistry (called “original” and “extended”) predicted engine thermodynamics and emissions. While the original model reproduced in-cylinder pressure and combustion phasing, it failed to capture the effect of fuel composition or operating condition on NO trends, both under- and over-predicting them for neat NH3 and CH4-rich operations. An extension of the model incorporating a burned-zone batch reactor and two more reactors simulating the post-combustion oxidation of the mixture exiting crevices and the DeNOx processes during exhaust blowdown were implemented to address these limitations. Analysis of NO formation pathways highlighted the differences between modeling approaches. The equilibrium assumptions in the original model restricted NO formation primarily to thermal (Zeldovich) mechanisms. In contrast, the kinetics-driven model showed that non-thermal pathways dominate NO formation for all NH3-containing cases, which shows the limitations of conventional SI models developed for hydrocarbons when applied to nitrogen-containing fuels. Post-combustion homogeneous reactors for crevice-based oxidation and exhaust blowdown revealed significant NO and N2O formation after the end of combustion at moderate temperatures (850–1200 K), suggesting that N2O formation was dominated by secondary thermal processes. Therefore, the inclusion of post-combustion chemistry and more consistent models are essential for accurate emission prediction in NH3-fueled SI engines.

Trujillo Grisales, Juan, Saenz Prado, Stefany, Alvarez, Luis F., Akkerman, Vyacheslav, Dumitrescu, Cosmin E.

Methane Emission Mitigation in Large-Bore Dual-Fuel Engines via Negative Valve Overlap Diesel Injection: Thermochemical Pathways and Reactivity Control

2026-37-0045

6/9/2026

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

Advanced Silicone Materials for Harsh Aerospace Environments

26AERP06_01

6/1/2026

Aerospace and defense systems demand materials capable of maintaining performance under extreme environmental and operational stressors, including wide thermal cycling ranges, exposure to hydrocarbon fuels, vacuum conditions, and repeated mechanical strain. Silicone-based materials have become essential in these environments because they can retain elasticity, stability, and functionality where many traditional materials fail. Silicones are widely used as coatings, adhesives, sealants, and elastomers in aircraft and spacecraft applications. Their chemical structure enables resistance to both high and low temperatures, while also providing durability against solvents and fuels such as jet fuel. In contrast, many conventional elastomers degrade under prolonged thermal exposure or become brittle at cryogenic temperatures.

Experimental Investigation of Diesel, Aqueous Ammonia, and Compressed Natural Gas Mixtures on Performance and Emissions in a Compression Ignition Engine

04-19-03-0011

5/30/2026

Abstract This study investigates and evaluates systematically the combustion, performance, and emissions characteristics of heavy-duty diesel engines fueled by diesel–ammonia–compressed natural gas triple blends. While dual-fuel systems are well-documented, the interactive effects of ammonia and CNG within a single compression ignition (CI) engine remain largely unexplored. Experiments were conducted on a 300 Nm, 660 rpm diesel engine by testing pure diesel, diesel–ammonia blends (10–20 wt.% aqueous ammonia), and triple-fuel mixtures containing 10% of the total energy from compressed natural gas. Pure diesel was first tested to provide baseline data, and subsequently blends were tested for a comparative study. The primary contribution of this work is the identification of a synergistic effect of the fuel triple blends on engine performance and emissions. Results indicate that all fuel blends improve thermal efficiency and reduce fuel consumption compared to conventional diesel. The blend containing 20% aqueous ammonia, 80% diesel, and 10% of the total fuel energy supplied by compressed natural gas achieved the highest thermal efficiency of 39.7% (7% higher than diesel) and the lowest brake specific fuel consumption of 211.22 g/kWh. Furthermore, emissions analysis revealed that carbon dioxide and nitrogen oxide emissions were significantly reduced with this triple blend. The blend decreased carbon dioxide by 26.6% and nitrogen oxide emissions by 32.1%, while hydrocarbon emissions were also lowered by up to 29.2%. Carbon monoxide emissions increased slightly for the triple blends, reaching a maximum value of 3.9028 g/kWh for the A20D80CNG10 mixture, compared to diesel operation. The slight increase in carbon monoxide emissions for triple blends highlights a trade-off in emission behavior. These findings address the combined utilization of diesel–ammonia–compressed natural gas triple-fuel mixtures in heavy-duty engines, demonstrating that strategic blending can simultaneously improve efficiency while mitigating environmental impact. Graphical Abstract

Sinkala, Happy, Sarıtaş, Mehmet, Kül, Volkan Sabri, Akansu, Selahaddin Orhan, Ünalan, Sebahattin

2025 Student Design Competition Graduate Winner: University of Maryland Wyvern Design Pioneering Hydrogen-Electric VTOL

F-0082-2026-0344

5/5/2026

In response to the 42nd (2025) Annual VFS Student Design Competition, the Graduate Student Design Team from the University of Maryland introduces Wyvern, a novel hydrogen-powered electric compound rotor-craft engineered for maximum loiter and operational safety. Named after a mythical dragon that defies convention by not breathing fire, Wyvern only breathes water vapor by forgoing hydrocarbon combustion in favor of the quiet and clean power of hydrogen. This design reflects not only an aeronautical solution to an engineering challenge but a greater aspiration to reshaping how practical and clean vertical flight can be achieved.

Basak, Kumardip, Ogle, William

Effect of Exhaust Gas Components on Oxygen Storage Capacity Measurements of Automotive Catalysts

2026-01-0360

4/7/2026

Three-way catalytic converters (TWC) are one of the most popular methods to help reduce harmful tailpipe emissions emitted from internal combustion (IC) vehicles. To help improve conversion efficiency, TWCs can store and release oxygen via an oxygen storage capacity (OSC) mechanism. During engine control unit (ECU) calibration, on board OSC measurements are correlated to TWC and vehicle emissions to monitor emissions performance throughout the full useful life (FUL) of the vehicle. It is known that different test conditions, including temperature, space velocity and background gases in the exhaust stream affect OSC measurement, potentially altering the calculated OSC values and thus the perceived level of OSC and emissions preformance during operation. This study utilises an OMEGA test bench to complete OSC measurements on the full-scale automotive catalyst samples to quantify the effects of different background gases including carbon monoxide, hydrocarbons and nitric oxide on OSC measurements, concluding that all background gases studied affect measured OSC values. The study revealed that hydrocarbons had the largest effect on OSC measurement increasing OSC values by up to 50%. It was concluded that the increase in OSC measurement with injected hydrocarbons was due to the breakdown of hydrocarbons on the catalyst surface during rich periods of operation increasing the amount of oxygen required to fully oxidise the catalyst resulting in a larger perceived OSC measurement. During the initial ECU calibration original equipment manufacturers (OEM) should consider these effects on OSC measurement and understand how this will affect perceived OSC and vehicle emissions performance for FUL and onboard diagnostics (OBD) applications. This will help ensure emissions compliance and guide optimized catalyst and engine calibrations.

Mc Grane, Liam, Douglas, Roy, Irwin, Kurtis, Woods, Andrew, Elliott, Matthew, Istrate, Oana, Nockemann, Peter

Study of Deposit Control Additive Efficacy in Gasoline Direct Injection Engines

2026-01-0349

4/7/2026

There is an increasing adoption of Direct-Injection Spark-Ignition (DISI) engines in the market, which per 2024 US Environmental Protection Agency (EPA) Automotive Trends Report represents 73% of new vehicles sold in the US. And while it is well accepted that DISI offers advantages over Port Fuel Injection (PFI) technology in meeting stringent CO2 emissions and fuel economy requirements set by the EPA, DISI engines are also associated with increased formation of injector deposits. These deposits may foul injectors and accumulate on the injector tip causing distorted spray patterns and diffusive combustion. Ultimately, this leads to engine performance deterioration and increased harmful emissions. To control deposit formation, detergent-type chemistries are added to the fuel in small amounts. Deposit Control Additives (DCAs) function by preventing the formation of deleterious injector deposits as well as removing existing ones. This study used standardized protocols describing the assessment of DCA in controlling injector deposits that have been developed by industry in both the US and Europe. When used at standard concentrations, DCA showed some engine performance and emission benefits over untreated base fuel. This investigation also demonstrated that engine performance can be recovered, in an engine with fouled injectors, with the use of higher DCA concentrations, accompanied by improved fuel economy and reduced particulate and total hydrocarbon emissions. This further confirms previous findings that, although DCA increases gum levels in the fuel, higher concentrations of DCAs improve injector cleanliness enough to outweigh any negative impacts from the increased gum content.

Soriano, Nestor, Williams, Rod, Cracknell, Roger, Lang, Wendy, Chahal, Jasprit

Effect of Renewable Fuel Blends on Particulate Emissions under Medium Engine Load and Injector Coking Conditions in a GDI Engine

2026-01-0301

4/7/2026

Renewable gasoline is blended with fossil gasoline as part of the effort to achieve zero net carbon emissions. This study examined how five gasoline fuels with different hydrocarbon compositions affect engine-out gaseous and particle number (PN) emissions. Gasolines F3 and F4 reduce GHG emissions by 54% and 35%, compared with fossil gasoline. The other three gasolines reduce GHG emissions by 4-9%. Tests were conducted on a single-cylinder GDI engine at 10-14 bar indicated mean effective pressure (IMEP) and 2000 rpm. The injector-tip coking behavior of the test fuels and the resulting PN emissions were also investigated at 10 bar IMEP. Spray plume targets and start-of-injection (SOI) timing were adjusted to examine how the test fuels affected PN emissions. An endoscope was used to identify the sources of soot during fuel combustion. The experimental results show that PN varies with gasoline composition and engine operating conditions. Aromatics and olefins contribute more to injector coking. Coked injector conditions showed 95% higher PN than clean injector conditions. Reducing the injector umbrella angle reduces coking. At 10-14 bar IMEP, PN emissions increased with higher aromatics content in the gasoline. Additionally, olefins and naphthene contributed to PN at higher IMEPs. 10-200 nm size particles accounted for 70-95% of total particles. Gasoline with higher C9+ aromatics and T50 to FBP values showed higher 10-200 nm particles. Replacing 10% of paraffins with olefins and naphthene in gasoline changed >10 nm particles by 25%. Increasing 4% paraffins and decreasing 4.5% aromatics in gasoline reduced PN emissions by 125%. Increasing the aromatics content of gasoline by 8% increased fuel consumption by 2% and hydrocarbon emissions by 30%. Retarding the SOI timing by 20 CAD reduced PN emissions by 60%.

Muniappan, Krishnamoorthi, Dahlander, Petter, Helmantel, Ayolt, Alemahdi, Nika, Lehto, Kalle

The Impact of Various Renewable Hydrocarbons on Performance and Emissions in a Super Lean Burn Engine

2026-01-0306

4/7/2026

Compared to regular fuels, biofuels can play a key role as low-carbon transitional energy sources for ICE vehicles as the fleet moves towards increasing electrification. Blending of ethanol plays a key role in enhancing the anti-knock properties of the fuel and also allows renewable hydrocarbons (such as bio-naphtha) to be incorporated into the blend whilst maintaining an acceptable overall fuel quality. Super lean burn ICE technology with λ between 2 and 3 can lead to enhanced fuel economy and reduced NOx emissions. The Toyota prototype engine used to generate data for this project injects most of the fuel in PFI mode to generate a homogeneous super-lean charge in the cylinder, but just before spark ignition the DI injector sprays a small amount of fuel towards the spark plug to create a richer charge near the spark plug to promote flame kernel development. Various fuel formulations with high biofuel content were tested in both conventional and super lean burn engines. Certain fuel compositions were formulated with faster burning components such as ethyl benzene. The super lean burn engine showed a clear link between faster combustion and minimization of unburned fuel losses, thereby resulting in a further efficiency benefit. The effect of fuel composition on particulate emissions was more complex: although the conventional engine emitted higher particulate numbers (PN) when operating on fuels with a higher content of heavier aromatics (as might be predicted from standard particulate index approaches), the super lean burn engine suggests that additional factors are at play which are discussed in the paper.

Aradi, Allen, Krueger-Venus, Jens, Jain, Sandeep Kumar, Cracknell, Roger, Kolbeck, Andreas, Shibuya, Masahiko, Yamada, Ryota, Matsubara, Naoyoshi, Kitano, Koji

Effect of Renewable Fuel Blends on Particulate Emissions in Warm-Up Conditions in a GDI Engine

2026-01-0304

4/7/2026

Renewable gasoline offers significant benefits in reducing greenhouse gas (GHG) emissions. In this study, five gasolines with different renewable hydrocarbon classes and varying distillation curves were taken to investigate their effect on particle number (PN) emissions in a spark-ignition GDI engine at 10 bar indicated mean effective pressure (IMEP) and 2000 rpm. The engine coolant temperature was varied from 90°C to 35°C to investigate the effect of fuel evaporation on soot formation. Injectors with various spray plume targets and start of injection (SOI) timing (300° and 260° bTDC) were used to assess how different gasolines affect engine performance and to determine engine calibration requirements. A simplified transient cycle examines how engine motoring influences PN emissions for test gasolines. A high-speed camera and endoscope were used to identify the sources of soot during fuel combustion. Simulations were done to assess the quality of fuel-air mixing in support of the experimental data. The results revealed that the type of hydrocarbons in gasoline was crucially affecting PN emissions. Particles with >10 nm increased with increasing fuel’s aromatics. Paraffin-rich gasoline showed 71% and 98% lower PN than aromatics-rich gasoline under hot and cold engine conditions. Paraffin-rich gasoline showed lower PN in cold tests than in hot tests with retarded SOI. Replacing ~10% paraffins with olefins and naphthene reduced >10 nm PN by 15-77%. However, replacing 19% of paraffins with olefins and naphthene increases PN emissions. Optimal SOI timing reduces PN by 80% for aromatics-rich gasoline. Fuel consumption and hydrocarbon (HC) emissions increased with increasing aromatics and paraffins in gasoline under cold conditions. Yellow flames on the piston top and near the injector tip were the primary sources of soot. Simulation results showed that the liquid fuel mass increased by 14% when the coolant temperature was reduced by 55 K.

Muniappan, Krishnamoorthi, Dahlander, Petter, Helmantel, Ayolt, Alemahdi, Nika, Lehto, Kalle

Achieving Euro 7 WHSC NOx Emission Targets from a Spark Ignited Engine Using Methanol-Hydrogen Co-Fuelling

2026-01-0321

4/7/2026

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 Chamber

2026-01-0348

4/7/2026

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

Effect of E20 Fuel on Vehicle Performance Parameters of 694CC Gasoline Engine for Commercial Vehicle Application

2026-26-0565

1/16/2026

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

Advancement in Analytical Characterization of NBR: Py-GC-MS as an Alternative to NMR for Acrylonitrile Quantification

2026-26-0546

1/16/2026

Nitrile Butadiene Rubber (NBR), known for its superior resistance to hydrocarbon oil, low gas permeability, and excellent thermal stability, finds extensive use in seals, O-rings, conveyor belts etc. Importantly, these performance attributes are chiefly governed by acrylonitrile content in NBR. Analytical characterization of raw NBR is relatively straightforward using conventional techniques such as elemental analysis (CHNS) and liquid state 13C NMR. In contrast, the analysis of vulcanized NBR presents considerable challenges due to its crosslinked structure, which renders it insoluble in most organic and inorganic solvents, thereby restricting direct molecular-level analysis. While solid-state 13C NMR is an established technique for structural characterization in rubber vulcanizates, its high-cost curbs routine industrial analysis. In this study, Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) technique has been explored as a robust, precise, cost-effective alternative. Quantitative determination of acrylonitrile (ACN) content in vulcanized NBR, covering a compositional range of 15% to 52% is carried out using Py-GC-MS. For sequence distribution of ACN units, liquid-state 13C NMR, is utilized exclusively for soluble, uncured NBR. The absolute ACN content values thus obtained serve as reference standards for validating the Py-GC-MS method, enabling robust quantification across both raw and cured material forms.

Samanta, Rajyasree, Ghosh, Debojit, Anjana, Kanhaiya, Sen, Amit, Guria, Biswanath, Chanda, Jagannath, Samui, Barun, Ghosh, Prasenjit, Mukhopadhyay, Rabindra

Replacing Diesel Engines with CNG Engines – Impact on Emissions, Based on Chassis Dynamometer Tests of Medium and Heavy-Duty Buses

2026-26-0127

1/16/2026

This paper compares carbon dioxide, carbon monoxide, methane, and oxides of nitrogen emissions from medium and heavy-duty buses using diesel, diesel-hybrid, and CNG powertrains. Comparisons are made using results from chassis dynamometer-based tests with driving cycles intended to simulate a wide range of operating conditions. Tail pipe emissions are measured by diluting the vehicle’s exhaust in a full-scale dilution tunnel by mixing with conditioned air. Samples are drawn through probes of raw exhaust, diluted exhaust and measured using laboratory grade emission analyzers. Fuel consumption of diesel is measured using a weighing scale, while a gas flow meter is used for measuring CNG consumption. Experimental data from 19 buses tested on a chassis dynamometer over the last 8 years has been analyzed and a comparison of results from similar buses with the differently fueled powertrains is presented. Based on these test results, it is shown that replacing diesel engines with CNG engines does not significantly reduce the emissions of carbon dioxide, while it increases carbon monoxide and methane emissions, reduces oxides of nitrogen emissions, and does not substantially help to reduce global warming.

Iyer, Suresh

A Thermoelectric System for Emission Control Optimization in Two-Wheeler Automotive Applications

2026-26-0218

1/16/2026

Environmental pollution is one of the growing concerns of our society. As vehicle emissions are a major contributor to air pollution, emission control is a primary goal of the Automotive industry. Vehicle emissions are higher due to improper combustion, which leads to toxic gases being generated from the exhaust system. Unburnt fuel is one of the leading causes of toxic pollutants such as Carbon Monoxide, Nitric Oxides (NOx) and Hydrocarbons. The catalytic converter converts these gases into less toxic substances such as Carbon Dioxide, Nitrogen, and water vapor. The catalytic converter performs efficiently after reaching its “Light Off” temperature, after which the catalyst becomes active. Hence, elevated temperature of the exhaust gases aids in efficient conversion. Presently, the gases from the exhaust system are approximately at a temperature of 300°C-600°C. This paper outlines the concept of a Peltier (Thermoelectric) Module - based system, which helps maintain the high temperature of the exhaust gases prior to entering the catalytic converter. Peltier Modules are thermoelectric devices well-known for their usage in heating/cooling applications. The proposed system includes a chamber in which the Peltier Module is embedded. As the gases flow through the chamber, the embedded Peltier Module, which is powered by the battery, increases the temperature inside the chamber. Therefore, with this concept, the components required to heat the catalytic converter could be potentially reduced, since the exhaust gases will be maintained at the targeted temperature required for better emission control. Moreover, the Peltier Module is also known to be used for electricity generation. Consequently, by generating electricity through heat utilization on the surface of the chamber, we provide an added benefit of this proposed concept. This can be achieved by mounting the Peltier Module on the hot surface of the chamber. The other side of the Peltier Module is exposed to ambient air and thereby a potential difference is created through the Seebeck Effect.

Venkateshwaran, Aishwarya, Soodlu, Shashikiran, M, Mathaiyan

Improving Late Pilot Injection Strategy in Dual-Fuel Diesel/Methane Engines through Supercharging and Hydrogen Enrichment

03-18-08-0049

12/24/2025

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

Investigation of the Performance and Emissions of a Compression Ignition Mechanical Engine Operating in a Dual-Fuel Mode with Diesel and CNG

2025-36-0127

12/18/2025

This study investigates the impact of adding compressed natural gas (CNG) to diesel on the performance of a compression ignition engine. In diesel dual-fuel systems, CNG is used to replace part of the energy originally supplied by diesel. The objective is to evaluate the performance of an Agrale BX6110 agricultural tractor engine operating in dual-fuel mode, with simple adaptations that allow it to function in its original mode as well, ensuring easy reversibility. Additionally, CNG can represent a cost-effective and environmentally advantageous alternative for farmers, significantly reducing their operational costs. Tests were conducted with four different CNG injection cases and three diesel injection cases, using an AW Dynamometer NEB 200 test bench. The maximum diesel substitution by CNG was 45.20%. In dual-fuel mode, the engine achieved maximum torque and power values of 665 N·m and 37.3 kW, respectively, representing a 20.45% loss compared to diesel-only operation. A reduction of 20.50% in carbon dioxide (CO2) emissions was observed, while unburned hydrocarbon emissions increased by approximately 4.52 times. Through economic analysis, it was concluded that, at the point of maximum torque and power operating in dual-fuel mode, a cost reduction of 14.32% per kWh produced was achieved.

Oliveira, Lucas, Alvarez, Carlos Eduardo Castilla, Cesar, Felipe

Effect of Fuel Injection Strategies on Performance, Combustion, and Emission Characteristics of Diesel–Diethyl Ether–Fueled Compression Ignition Engine

03-18-07-0043

11/20/2025

This experimental study compared a blend of diesel–DEE (DEE 40% v/v in diesel) with baseline diesel. This experimental study assesses different fuel injection strategies for controlling the in-cylinder charge stratification, such as single, double, and triple injections. The peak in-cylinder pressure under the partially premixed combustion mode was higher than conventional diesel combustion. Higher in-cylinder pressure with increasing dwell time was observed under triple injections. Retarding pilot injections increased the peak in-cylinder pressure. Conventional diesel combustion mode exhibited the highest brake thermal efficiency and lowest emissions with all injection strategies. A longer dwell time of 12° CA showed higher brake thermal efficiency, nitric oxide, and carbon monoxide emissions, whereas hydrocarbon emissions were lower compared to a shorter dwell time of 6° CA. Hydrocarbon and carbon monoxide emissions increased, but nitric oxide and brake thermal efficiency were reduced by advancing pilot injections. The diesel–DEE blend exhibited slightly lower brake thermal efficiency than baseline diesel at all injection strategies, except for the conventional diesel combustion mode. Diesel–DEE blend exhibited higher hydrocarbon and carbon monoxide emissions than baseline diesel, but nitric oxide emissions were lower.

Sonawane, Utkarsha, Agarwal, Avinash Kumar

Computational Investigation on a Boosted Uniflow Scavenged Direct-Injection Combustion Engine (BUSDICE) with Alcohol Fuels

2025-32-0027

11/3/2025

Alcohol fuels, produced from renewable energy sources, are considered a crucial solution for achieving life-cycle carbon neutrality in internal combustion engines. The Boosted Uniflow Scavenged Direct-Injection Combustion Engine (BUSDICE) exhibits significant potential for high thermal efficiency with an aggressive downsizing design. In this study, a computational investigation was carried out to assess the spray mixing and combustion characteristics of BUSDICE fuelled with methanol and ethanol, compared with gasoline, under a high-load condition. The injection duration of methanol and ethanol is significantly longer than that of iso-octane, leading to incomplete evaporation. The mixture exhibits an “outer-rich, central-lean” stratification pattern due to the short mixing time and swirl flow transportation for all three fuels. However, the prolonged injection of methanol induces stronger turbulence, which can enhance the local mixing. The spatial mixture stratification, particularly near the spark-local area, has a strong influence on the initial kernel development and flame propagation. Consequently, methanol exhibits a shorter ignition delay than ethanol under the same spark timing, leading to faster flame propagation attributed to a richer equivalence ratio around the spark plug. Nevertheless, the ignition and combustion performance of ethanol can be improved by advancing the spark timing. The spark timing study reveals that alcohol fuels can operate under high load without knocking, whereas iso-octane requires retarded ignition timing to prevent knocking. As a result, methanol and ethanol provide a better IMEP and ITE than iso-octane under high-load conditions. From an emissions perspective, due to their low carbon-to-hydrogen (C/H) ratio and high oxygen content, unburnt hydrocarbon emissions decrease significantly when using alcohol fuels, especially methanol, for which these emissions are almost zero. However, the soot of ethanol shows a slight increase than iso-octane, due to the highly stratified mixture and incomplete combustion. Additionally, the NOx of ethanol and methanol increases due to the higher combustion temperatures than iso-octane. Overall, the results highlight the strong potential of alcohol-fuelled BUSDICE engines as compact and sustainable solutions for small-displacement powertrains, offering high thermal efficiency and substantially reduced pollutant emissions.

Feng, Yizhuo, Lu, Enshen, Dong, Shuo, Keshtkar, Hossein, Wang, Xinyan, Zhao, Hua

Effect of Plasma-Assisted Ignition on Combustion and Emission Characteristics of Two Stroke Engines with Different Fuels

2025-32-0030

11/3/2025

This study explores the effect of plasma-assisted ignition (PAI) on combustion stability and emissions in two-stroke spark-ignition engines. Two engine platforms were evaluated: a conventional single-cylinder two-stroke engine and a thermodynamically advanced opposed-piston two-stroke (OP2S) engine. The OP2S engine configuration offers reduced heat loss and higher power density due to its uniflow scavenging and favorable geometry, but suffers from high residual gas fraction, which increases ignition difficulty and combustion instability. To address this, nanosecond-pulsed PAI was applied in various spatial arrangements and discharge voltages, using both gasoline and a low-reactivity gasoline/DMC blend fuel. Spark ignition timing was held constant at the minimum advance for best torque across all tests. Combustion stability was assessed via indicated mean effective pressure (IMEP) and its coefficient of variation, while CO and HC emissions were measured as environmental indicators. Results show that PAI significantly enhanced ignition stability, reducing COVIMEP by up to 84% and HC emissions by up to 24%, depending on fuel and engine type. The OP2S engine showed greater responsiveness to ignition configuration and plasma positioning due to its uniflow scavenging method. These findings confirm that PAI is a promising strategy for improving ignition robustness and emission performance in both conventional and advanced two-stroke engine architectures.

Liu, Jinru, Yamazaki, Yoshiaki, Otaki, Yusuke, Kato, Hayato, Kobayashi, Daichi, Umegaki, Tetsuo, Asai, Tomohiko, Iijima, Akira

Analysis of Flame Propagation Characteristics in a Hydrogen Engine using an Optically Accessible Engine

2025-32-0061

11/3/2025

This study focused on the effects of hydrogen on the flame propagation characteristics and combustion characteristics of a small spark-ignition engine. The combustion flame in the cylinder was observed using a side-valve engine that allowed optical access. The fundamental characteristics of hydrogen combustion were investigated based on combustion images photographed in the cylinder with a high-speed camera and measured cylinder pressure waveforms. Experiments were conducted under various ignition timings and equivalence ratios and comparisons were made with the characteristics of an existing hydrocarbon liquid fuel. The hydrogen flame was successfully photographed, although it has been regarded as being difficult to visualize, thus enabling calculation of the flame propagation speed. As a result, it was found that the flame propagation speed of hydrogen was much faster than that of the existing hydrocarbon fuel. On the other hand, it was difficult to photograph the hydrogen flame directly in the lean region. In future studies, it will be necessary to reduce the shooting speed or to conduct investigations based on spectroscopic measurements. Regarding hydrogen combustion, it was found that the combustible range of hydrogen was broad even when the experimental conditions were substantially varied. It was also found that the combustible period was much shorter than that of the existing hydrocarbon fuel. Misfiring and after-firing were observed in hydrogen combustion where the ignition timing was close to top dead center as well as under a lean condition. This confirmed that there are issues concerning hydrogen combustion stability under such conditions.

Arai, Yuto, Ueno, Takamori, Suda, Ryosuke, Sato, Ryoichi, Nakao, Yoshinori, Ninomiya, Yoshinari, Matsushita, Koichiro, Kamio, Tomohiko, Iijima, Akira

First Investigation of Ducted Fuel Injection on a Retrofitted Heavy-Duty Multi-Cylinder Production Engine

04-19-01-0005

10/22/2025

Ducted fuel injection (DFI) was tested for the first time on a production multi-cylinder engine. Design-of-experiments (DoE) testing was carried out for DFI with a baseline ultra-low sulfur diesel (ULSD) fuel as well as three fuels with lower lifecycle carbon dioxide (CO2) emissions: renewable diesel, neat biodiesel (from soy), and a 50/50 blend by volume of biodiesel with renewable diesel denoted B50R50. For all fuels tested, DFI enabled simultaneous reductions of engine-out emissions of soot and nitrogen oxides (NOx) with late injection timings. DoE data were used to develop individual calibrations for steady-state testing with each fuel using the ISO 8178 eight-mode off-road test cycle. Over the ISO 8178 test, DFI with a five-duct configuration and B50R50 fuel reduced soot and NOx by 87% and 42%, respectively, relative to the production engine calibration. Soot reductions generally decreased with increasing engine load. Hydrocarbon and carbon monoxide emissions tended to increase with DFI but were not excessive over the ISO 8178 test. Brake-specific energy consumption generally increased with DFI due to the use of retarded injection timings and exhaust-gas recirculation to achieve the desired NOx reductions but was less than or equal to that for conventional diesel combustion with ULSD at a similar NOx level. Significant deposits were encountered on one cylinder when running at idle with the ULSD fuel only, but this was mitigated by replacing the corresponding fuel injector (which showed deformation at the exits of two of its orifices) and using a fuel detergent additive in subsequent testing. In all, the engine was successfully operated for over 300 hours in the DFI configuration. Research areas for improved DFI implementation are identified.

Ogren, Ryan M., Baumgard, Kirby J., Radhakrishna, Vishnu, Kempin, Robert C., Mueller, Charles J.

Optimal Sets of Molecules to Predict Aviation Fuel Properties

2025-01-0395

10/7/2025

The complexity and variability of modern aviation fuels necessitate the development of robust and efficient tools to assess their properties accurately, particularly within the certification framework established by the American Society for Testing and Materials (ASTM). Therefore, previous research has developed predictive models to reduce the experimental burden by predicting aviation fuel properties from broad chemical classes. While two-dimensional Gas Chromatography (GC×GC) provides detailed compositional information, it only identifies the weight of hydrocarbon families (aromatics, cycloalkanes, n-alkanes, iso-alkanes), not individual molecules. Aviation fuels are complex, and their composition can contain more than 60 key classes, the majority of which are isomeric. As a result, an exceptionally high number of possible molecule combinations makes random selection prone to high errors in property prediction. To this end, we used a Monte Carlo approach to search for the optimal combination of 64 hydrocarbon molecules from this vast combinatorial space. By exploring up to 500 million combinations, we aim to determine the molecule set that best predicts mass density, kinematic viscosity, and distillation temperature using linear mixing rules. These rules calculate the properties of molecule mixtures using the weight of each molecule in the mixture and the pure molecules’ properties. We used experimental data for various aviation fuels, including conventional jet fuels, sustainable aviation fuels, and rocket propulsion fuels. Results showed that the isomeric effect has a substantial role in predicting mass density, kinematic viscosity, and the distillation temperature. Results showed that the linear mixing rules could outperform machine learning that overlooks the isomeric effect for the three properties. This research benefits the surrogate fuel analysis, which requires defining a surrogate mixture of hydrocarbon molecules, and will provide insights into the best isomers or molecules to choose to predict aviation fuel properties with the least error. This work will help deliver aviation fuel producers with a relatively accurate pre-screening tool for property prediction, minimizing the need for iterative experimental processes.

Radaideh, Mohammed I., Kim, Doohyun, Radaideh, Majdi, Violi, Angela

Experimental and Numerical Insights on Emissions Control with a Diesel Oxidation Catalyst in Reactivity-Controlled Compression Ignition Combustion Conditions

03-18-05-0034

9/1/2025

Reactivity-controlled compression ignition (RCCI), a low-temperature combustion strategy, reduces oxides of nitrogen (NOx) and soot simultaneously; however, high concentrations of carbon monoxide (CO) and total hydrocarbons (THC) and low exhaust gas temperatures pose a significant challenge for the catalytic control of tailpipe CO and THC. Diesel oxidation catalyst (DOC) is generally used in compression ignition (CI) engines for CO, THC, and nitric oxide (NO) oxidation. This work provides a new understanding of the performance characteristics of a DOC in the RCCI combustion strategy with various gasoline–diesel fuel premix ratios ranging from ~46% to ~70% at steady-state operating conditions. Experimental insights from the RCCI strategy prompt considerations of both CO and THC oxidations and THC trap functionalities in the 1D transient model of the DOC. It is observed that an increase in the fuel premix ratio from 50% to 70% in RCCI shifts the CO and THC oxidation characteristics curves by up to 10°C toward low exhaust gas temperatures. The evolution of the catalyst surface temperature with exhaust gas temperature reveals distinct stages of heat transfer, indicating a progressive shift of oxidation reactions from the back to the front side of the DOC channel. Furthermore, axial variations of the oxidation characteristics of the DOC reveal that CO oxidizes over a narrow length of the DOC as compared to THC. Additionally, a nondimensional analysis is carried out to identify kinetic-controlled and mass transfer–controlled regimes of CO and THC oxidations, indicating that both CO and THC are in kinetic-controlled regimes at exhaust gas temperatures lower than 192°C, and transitioning into a mass transfer–controlled regime above this temperature.

Suman, Abhishek, Sarangi, Asish Kumar, Herreros, Jose Martin

Drop-In Performance of Propyl- and Butyl-Terminated Oxymethylene Ethers in a Compression Ignition Engine

04-19-01-0003

7/16/2025

Oxymethylene ethers (OMEs) have been proposed for use in diesel engines as a high-reactivity fuel with reduced soot emission. Historically, the focus on methyl-terminated OMEs has limited drop-in applicability. In this work, a set of extended-alkyl OMEs with methyl, propyl, and butyl terminations are tested in an unmodified 4.5L Deere diesel engine, neat and in various blends with ultra-low-sulfur diesel (ULSD). Engine operability and emissions data are collected for the various fuel blends. External laboratory testing against the ASTM D975 standard demonstrates that a blend of 30% butyl-terminated OMEs with ULSD meets all ASTM standard requirements except lubricity. It is shown that the OMEs and OME–diesel blends demonstrate shorter combustion durations, as defined by the 10%–90% heat release timing, than the ULSD control. Engine brake efficiency is unaffected by OME usage, while specific fuel consumption increases in proportion to the reduced heating values of OMEs. Particulate emissions are reduced to a greater extent for all OMEs and OME blends than the blend ratio would suggest when using the yield sooting index as an estimator. NOx emissions from the OMEs and OME blends are increased with respect to ULSD; however, the increase in NOx is much lower than the decrease in particulates, indicating a possible improvement in the soot/NOx tradeoff seen in combustion engines. Two observed downsides are increases in unburned hydrocarbon and formaldehyde emissions. Overall, butyl-terminated OMEs are recommended for future study as the ideal diesel blendstock studied in this work, with good balance of matching properties and improved emissions performance.

Lucas, Stephen P., Zdanowicz, Andrew, Wolff, Wyatt W., Windom, Bret

Effect of Water Dilution and Homogenous Lean Operation on Combustion and Detailed Emissions in a Spark Ignited Gasoline Direct Injection Engine

04-19-01-0004

7/10/2025

Twenty-nine percent of the greenhouse gas emissions in the US are produced by the transportation sector according to the US Environmental Protection Agency. The combination of increasingly stringent regulations on emissions and fuel economy, along with the current practical limitations of electrification motivate continued development efforts for improving internal combustion engine efficiency and emissions. Ethanol, an extensive fuel additive or drop-in replacement for gasoline, is already recognized as a promising transition fuel in decarbonization efforts. Furthermore, lean combustion in spark-ignited (SI) engines has been pursued extensively for engine efficiency and emissions improvements. Lean combustion, however, faces the challenges of decreased combustion stability and strong increases to engine-out NOx at conditions where conventional SI engines are stable (ϕ > 0.7). Water dilution, historically used as a knock inhibitor in performance engines, has shown potential for improving both emissions and efficiency in modern engines. This study evaluates the combined impact of homogeneous lean operation and water dilution on a 2.4L 4-cylinder naturally aspirated (NA) gasoline direct injection (GDI) engine fueled with a gasoline ethanol blend. The results indicate that efficiency during stable lean operation is maintained or improved, and NOx emissions are reduced by 15–40% depending on the level of water dilution. The lean stability limit is slightly degraded with water dilution; however, the decrease in NOx emissions allow for less lean operation while maintaining non-water-dilute efficiency improvement and emissions reduction. Detailed hydrocarbon emissions reveal that ethanol is nearly three times more sensitive to water dilution than gasoline, and hydrocarbon kinetic pathways associated with ethanol show a similar increased sensitivity to water dilution.

Voris, Alex, Lundberg, Matt, Puzinauskas, Paulius

Effects of Double Injection Strategy in a Diesel-Ammonia Dual-Fuel Engine

2025-01-0206

6/16/2025

This study investigates the application of a double injection strategy in a single-cylinder marine diesel-ammonia dual-fuel engine retrofitted for experimental analysis. A diesel micro-pilot (MP) injection was used to ignite ammonia combustion, and diesel and ammonia were injected separately into the cylinder through dedicated injectors. The first MP injection timing was fixed at reference injection timing, and both early and late double MP injection strategies were implemented to evaluate their effects on ammonia combustion, engine performance, and exhaust emissions. Under all conditions, the ammonia injection timing remained constant. Early double injection strategies, with the second MP injection occurring before the first, enhanced premixed diesel combustion by raising in-cylinder temperature and pressure. However, this early heat release was ineffective for ammonia evaporation and combustion due to poor timing alignment. In contrast, late double injection strategies, with the second MP injection occurring between +75–105 CAD after reference injection timing, improved ammonia combustion by targeting the diesel spray at unburned ammonia in the squish region near the cylinder liner, where flame quenching typically occurs. Consequently, late MP injections reduced unburned ammonia emissions but led to higher N2O and hydrocarbon emissions due to slower oxidation rates in the squish region. Additionally, thermal efficiency declined due to decreased work conversion efficiency. Unburned ammonia above a certain level was detected under all conditions, primarily due to injector asymmetry, which led to incomplete combustion in specific regions of the cylinder. These findings underscore the importance of optimizing diesel pilot injection timing to enhance ammonia combustion while managing trade-offs in emissions and efficiency in dual-fuel engines.

Park, Chansoo, Jang, Ilpum, Park, Cheolwoong, Kim, Minki, Park, Gyeongtae

Investigating Lubricants Base Oils Reactivity in Ammonia Engines via Accelerated Aging

2025-01-0240

6/16/2025

As a carbon-free molecule, ammonia is more and more considered as a relevant fuel for long distance and off-road applications. However, this gas has different combustion characteristics compared to conventional fuels, challenging the suitability of lubricants to such engines. In this work, the evolution of lubricants under conditions mimicking ammonia combustion was assessed. Mineral and polyester lubricant base oils were exposed to oxygen, nitrogen oxides, and ammonia in a pressurized reactor under stirring. Oil aliquots were sampled at regular intervals, and characterized using Fourier Transform Infrared Spectroscopy (FTIR), viscosity and total oxygen and nitrogen contents measurements. Exposure to air containing nitrogen oxides resulted in quicker accumulation of oxidation products compared to neat air, for both the mineral and complex polyester base oil. Besides, exposure to gaseous ammonia in air resulted in a slower oxidation rate for both oils, compared to neat air. A global measurement of the total nitrogen content after 2 h showed a significant increase for both oils. Under similar conditions, the total nitrogen content of the polyester base oil was higher than the mineral oil, indicating a higher affinity of the ammonia with this matrix. Chromatograms obtained with a Gas Chromatography (GC) column associated to a Nitrogen Chemiluminescence Detector (NCD) showed that nitrogen speciation evolved from nitrogen contained in very light molecules, likely dissolved ammonia, to molecular nitrogen distributed across the entire range of hydrocarbon chain lengths. This demonstrates that ammonia reacted with the base oils and their degradation products. Two-dimensional gas chromatography and mass spectrometry will be performed in the upcoming months to identify these new kinds of degradation products. This study paves the way towards a better understanding of oil reactivity when exposed to ammonia combustion byproducts, including outcomes on engine operation and emissions of pollutants.

Doncoeur, Carole, Giarracca, Lucia, Cologon, Perrine, Rousselle, Christine

Understanding How Blending Different Ratios of Renewable Fuels with Diesel Impacts the Toxicity of Exhaust Particulates to Human Health

2025-01-0207

6/16/2025

The urgent need to decarbonise transport has increased the utilisation of renewable fuels blended with current hydrocarbons. Heavy duty vehicle electrification solutions are yet to be realised and therefore the reliance on diesel engines may still be present for decades to come. Currently, the diesel supplied to fuel stations across the UK is a 7% blended biodiesel, whilst in South Korea a 5% blend is utilised. Biodiesel is produced from renewable sources, for example, crops, waste residue, oils and biomass. Particulates from diesel combustion are known to be toxic due to the presence of polycyclic aromatic hydrocarbons (PAHs), however there is very limited understanding of blending oxygenated fuels on the toxicity of the particulates produced. PAHs are aromatic structures that can be metabolised into chemicals which can disrupt DNA replication and potentially influence cancer mechanisms if inhaled in high quantities. Soyabean methyl-ester (SME) was blended at lower ratios, e.g., 5%, 10%, 15% and combusted in a light duty direct injection diesel engine to investigate and collect particulate emissions. Gas-Chromatography Mass-Spectroscopy (GC-MS) was used to characterise and identify PAH content of the collected particulate samples. Results showed that the lower blend fuels produced a greater amount of large ring PAHs, which correlated with a higher toxic effect in experiments undertaken using in-vitro cell models with collected soot samples. This toxic effect was of greater significance than that observed from combustion of either 100% fossil diesel (FD) or 100% SME biodiesel. The toxic effects found highlight the need to better understand impacts of renewable fuel utilisation on human health.

Hailwood, Emma, Hellier, Paul, Ladommatos, Nicos, Leonard, Martin

Thermal Efficiency Improvement and Emission Reduction of Methanol Spark Ignition Engine Using Lean-Burn Strategy

2025-01-0224

6/16/2025

Methanol is a promising fuel for achieving carbon neutrality in the transportation sector, particularly for internal combustion engine vehicles. With its high-Octane number, methanol enables higher thermal efficiency compared to gasoline engines. Additionally, its wide flammability range allows stable engine operation under lean burn conditions at low to mid-load levels. These characteristics make methanol well-suited for lean-burn strategies, which reduce pumping losses and enhance thermal efficiency. However, there remains a lack of studies on the influence of injection timing under different lean conditions, particularly in a wall-guided spark ignition engine. Wall-guided systems use the chamber wall or piston surface to redirect and stratify the fuel-air mixture near the spark plug at the time of ignition. The combustion performance of lean-burn engines in highly sensitive to variations in injection and excess air ratio. In this study, experiments were conducted on a single-cylinder engine to examine the combustion and emission characteristics under varying excess air ratios and the injection timings. At an SOI of -180 CAD aTDC, a thermal efficiency of 47.5% was achieved when the excess air ratio was increased. This corresponds to a 5.62% improvement in efficiency compared to the condition with excess air ratio (λ) 1.2 condition, representing the largest increase among all tested conditions. Due to high thermal efficiency, high vaporization heat of methanol, and low combustion temperature of lean conditions, nitrogen oxides emission decreased from 10.24 g/kWh to 2.23 g/kWh. However, corrected hydrocarbon emission increased from 3.07 g/kWh to 6.98 g/kWh under SOI -120 CAD aTDC condition, leading to the decline in combustion efficiency.

Lee, Seungwon, Kim, Hyunsoo, Hwang, Joonsik, Bae, Choongsik

Effect of Ignition Condition and Fuel Octane Number on Knock Intensity in a Small 2-Stroke Engine

2025-01-0211

6/16/2025

Internal combustion engines (ICEs) remain widely used in automotive transportation for their high energy storage system efficiency and economic benefits. The 4-stroke engine has dominated all other forms to date, because the Otto cycle is relatively simple to understand. However, the significant benefits such as less pumping work and friction, lighter construction of 2-stroke engine, are attractive for applications that prioritize the simplicity and power density as well as meet the emission regulations. The disadvantages of the 2-stroke engine are mainly caused by the lack of sufficient scavenging process. Also, the overlap of the intake and exhaust phases results in charge short-circuiting, more fuel consumption and high unburned hydrocarbon emissions. For these reasons, it is difficult for 2-stroke engines to achieve stoichiometric combustion, making them incompatible with three-way catalyst to control emissions. The residual exhaust gas in the cylinder makes the spark ignition application leads to incomplete combustion and a higher coefficient of variation. Hence, it is imperative to investigate the effect of spark ignition strategies (ignition position, ignition timing conditions) on a portable small 2-stroke engine with complex in-cylinder gas flow distribution. In this study, we discussed the effect of spark ignition strategies on a small 2-stroke engine. In-cylinder combustion characteristics, emission characteristics and flame propagation process were observed by an optical 2-stroke engine with loop-scavenging. Additionally, in terms of fuel properties, gasoline, dimethyl carbonate/gasoline blend fuel and primary reference fuel are used to investigate the influence of ignition method on knock intensity with different octane numbers. To analyze the effect of fuel properties on combustion characteristics, the computational fluid dynamic (CFD) simulation using CONVERGE were conducted to predict the flame propagations. Through the experimental and CFD results, the potential for combustion improvement on 2-stroke spark ignition engine was evaluated by the optimization of ignition strategies.

Liu, Jinru, Yamazaki, Yoshiaki, Otaki, Yusuke, Kato, Hayato, Yokota, Takumi, Iijima, Akira

Research on Basic Characteristics of a Two-Stroke Opposed Piston Engine

2024-32-0112

4/18/2025

This study investigated the performance characteristics of a two-stroke opposed piston engine that is capable of constantly operating with high power output and high efficiency. An investigation was also made of the performance obtained by applying a pseudo uniflow condition as a measure against large hydrocarbon (HC) emissions owing to blow-by of unburned mixture, which is an issue of two-stroke engines. The test engine had a displacement of 127 cm3 and a bore and stroke of 48 x 70 mm. One-point and dual-point ignition systems were used, and regular gasoline was supplied as the test fuel using a carburetor-based fueling system. Experiments were conducted at engine speeds of 1500 and 3000 rpm at ignition timings of 45 deg. and 35 deg. before top dead center. The results showed that large quantities of HC emissions were emitted because stable combustion was not achieved. This revealed that a stronger uniflow condition must be applied as a countermeasure rather than a simple pseudo uniflow.

Fukushima, Shumpei, Uehara, Ryota, Hayashi, Yoshiaki, Igarashi, Ryo, Tokita, Kazuho, Iijima, Akira

Effects of Post-Injection Strategy on the Performance of Diesel Catalyst-Heating Operation

2025-01-8414

4/1/2025

Minimizing the time needed to achieve light-off temperatures in diesel engine aftertreatment devices is key to mitigate pollutant emissions during the first minutes of operation. Catalyst heating operation typically includes one or multiple post-injections late during the expansion stroke aimed to increase the enthalpy of the exhaust gases. However, post-injection retardability is constrained by low combustion efficiency and the formation of CO and unburned hydrocarbons that cannot be oxidized by a still-inactive oxidation catalyst. In this study, the effects of post-injection strategy on the performance and emissions of a medium duty diesel engine have been investigated experimentally, focusing on the impacts on post-injection retardability. A five injection strategy (two pilot, one main, two post) was implemented in the engine, and the injection duration ratio between the two post-injections has been varied systematically while performing post-injection timing sweeps to identify the trade-offs between exhaust enthalpy, emissions, fuel delivered by each post-injection, and post-injection timing. The exhaust enthalpy and the indicated specific CO and unburned hydrocarbon emissions increase as the post-injection retard for all the injection duration ratios. However, this effect is more dramatic for long first post injection durations and short second post injection durations (i.e., a high first-to-second post-injection duration ratio). For these cases, the fuel vaporization cooling effect of the first post-injection on the in-cylinder reactivity causes that both post injections burn together at lower in-cylinder temperatures than those of the other first-to-second injection duration ratios, leading to higher emissions with no significant advantages in exhaust enthalpy. In general, a fuel split ratio equal to 1 with half of the fuel injected in the second post-injection, which ignition is sustained by half of the fuel injected in the first post-injection provides better performance-emissions trade-off and higher post-injection retardability.

Lopez Pintor, Dario, Lee, Sanguk, Cho, Seokwon, Busch, Stephen, Wu, Angela, Narayanan, Abhinandhan, Abboud, Rami

Influence of Methanol-to-Gasoline Fuel Formulation on Knock Propensity and Flame Speed

2025-01-8400

4/1/2025

Drop-in gasoline fuels that originate from renewable, low-net-carbon sources, such as methanol-to-gasoline (MTG), are an important bridge in the transition between traditional fossil fuels and electrification of the transportation sector. The composition of these fuels can be tuned by adjusting the settings of the chemical processes used to create them, which can be leveraged to formulate optimized fuels for higher knock resistance or higher flame speed. This study investigated how the distribution of hydrocarbon classes and molecular structure of a renewable MTG gasoline surrogate affected knock and flame speed using chemical kinetic modeling. The original MTG surrogate was modified by increasing the relative amount of a certain hydrocarbon class while the concentration of other hydrocarbon classes is reduced equally. Increasing normal- and iso-alkanes increased reactivity and penalized octane sensitivity, olefins increased octane sensitivity while keeping the research octane number constant, and increasing cyclo-alkanes or aromatics decreased reactivity with the fuel being more sensitive to cyclo-alkanes. To optimize octane rating, short normal-alkanes and long, highly-branched iso-alkanes are preferred, with octane rating being very sensitive to the structure of iso-alkanes. Increased branching also improves octane rating for cyclo-alkanes, olefins, and aromatics. Regarding flame speed, normal-alkanes tend to increase flame speed at engine-relevant conditions because they form radicals that accelerate the flame. However, aromatics and cyclo-alkanes, which are promising octane boosters, showed lower flame speeds. Based on this understanding, an optimized MTG was formulated and compared against the effect of ethanol blending on the original MTG, with the optimized fuel showing similar performance as MTG with 52.5%vol ethanol. Chemical kinetic analyses showed that the chemistry that controls octane rating is different from that that controls flame speed, opening the door to fuels that simultaneously improve both knock and deflagration characteristics.

MacDonald, James, Lopez Pintor, Dario, Matsubara, Naoyoshi, Kitano, Koji, Yamada, Ryota

Comparison of Gasoline Particulate Indices Using U.S. Market Gasoline Samples

2025-01-8449

4/1/2025

Simulated distillation (SimDis) uses wide bore capillary gas chromatography (GC) to provide a detailed volatility profile of blended gasoline. The boiling point distribution from SimDis analysis is correlated to the hydrocarbon contents of spark ignition fuels and provide the resolution necessary to characterize the compositions of the fuel. Recent publications on simulated distillation applied to spark ignition fuel reveal the merits of indexing a gasoline fuel so that it can be correlated to the tendency of particulate emissions from vehicles. With this in mind, SimDis can be a useful and quick tool in assessing the PM-formation potential of market gasolines. Heavy aromatic compounds are compounds identified as having at least 10 Carbons and 1 aromatic ring. These compounds that are present in spark ignition fuels are major contributors to vehicle particulate emissions. These compounds can be found in the higher boiling portion (T70+) of the distillation profiles. As demonstrated in recent studies, the particulate indices of gasoline samples are indicative of the relative amount of particulate that a fuel forms during combustion. [1,2] These indices include Particulate Matter Index (PMI), Particulate Evaluation Index (PEI), and most recent PEISimDis calculation. [3,4,5] PMI and PEI require a detailed and lengthy GC separation process to yield the data needed for calculation. PEISimDis is reliant upon the much quicker method of SimDis and is primarily focused on the contributions from heavy aromatics. This paper will present a continued study of PEISimDis and its efficacy for PM prediction using a collection of the latest market gasoline fuel samples from the United States. How industry standard particulate indices are affected by PMI distribution, application of SimDis profiles, and the correlations of evaporative temperatures, especially above T90, will all be examined. Additionally, an analysis of SimDis cut-points (%-off values) of this collection of market samples will be performed to demonstrate the opportunity and effect of reducing the percent of heavy molecules for fuel quality improvement.

Goralski, Sarah, Geng, Pat, Dozier, Jon, Butler, Aron

Products of Tomorrow

TBMG-52824

4/1/2025

A Computational Investigation of Hydrogen Pre-Chamber and Spark-Ignition Combustion Engines at Different Load Conditions

2025-01-8406

4/1/2025

Pre-chamber (PC) technology has demonstrated its capability to achieve clean and stable combustion in internal combustion engines (ICEs) under lean conditions. This study evaluates the effectiveness of PC in direct injection (DI) hydrogen (H2)-ICEs compared to conventional spark ignition (SI) operation using high-fidelity computational fluid dynamics simulations across a range of load conditions. Various loads were attained by systematically adjusting intake pressure and injected H2 mass. The primary hypothesis posits that highly turbulent PC jets facilitate rapid mixing and combustion of ultra-lean mixtures. The comparative analysis revealed that DI fueling in both PC and SI modes did not achieve perfectly homogeneous mixtures, particularly under high load conditions, although PC slightly enhanced mixture uniformity. Combustion behavior exhibited a non-monotonic trend, with SI outperforming PC at low and high loads, while PC demonstrated superior performance at medium loads despite elevated heat transfer losses. Additionally, PC jets maintained high concentrations of OH radicals, promoting faster combustion and indicating potential for auto-ignition suppression. In conclusion, specific tasks for optimizing SI and PC systems were identified, providing clear directions for future research.

Menaca, Rafael, Liu, Xinlei, Mohan, Balaji, Cenker, Emre, AlRamadan, Abdullah, Im, Hong

Combustion and Emission Analysis of Pelletized vs. Raw Biomass Fuels

2025-28-0035

2/7/2025

Biomass fuels, such as sawdust and groundnut shells, are increasingly recognized as sustainable alternatives to fossil fuels. However, their high moisture content and loose structure result in low thermal efficiency. To improve performance, pellet forms of these fuels are often used. Naturally available raw and pellet forms of Sawdust, groundnut shell fuels have been utilized in this study. This study evaluates and compares the thermal efficiency of a gasifier cook stove and emissions from the combustion of raw and pellet forms of biomass fuels. It was found that the burning rate and firepower increase significantly with the use of pellet from of fuels. Sawdust pellets exhibited a highest thermal efficiency of 22.41%. The hydrocarbon (HC) levels for groundnut shell pellets were observed to range between 1 and 5 parts per million (ppm), while for sawdust pellets, it was observed to range from 1 to 6 ppm, indicating the preferable usage of pellets as fuel over raw form of biomass fuel.

Prasad, Malladi Jogendra, Vangipurapu, Bapi Raju

Effects of Injection Parameters On the Evaporation, Mixing, Combustion and Emission Characteristics of a Spark Ignition Methanol Engine

2025-01-7119

1/31/2025

The combustion performance test under different injection parameters was carried out on an inline 6-cylinder spark-ignition (SI) methanol engine, and the influence mechanism of injection parameters on methanol evaporation, mixing, combustion and emission was revealed through simulation. The results indicate that compared to the low-flow nozzle scheme (14*D0.26), when adopting the high-flow nozzle scheme (16*D0.30), the injection duration is shorter. The evaporation rate of methanol in the intake port is increased, the amount of methanol droplets and wall-attached liquid film in the cylinder is reduced, and the temperature in the cylinder is elevated. Moreover, the changes are more significant under high-load operating conditions. The change in the methanol charge rate during the intake process leads to a slightly higher inhomogeneity of the in-cylinder mixture. The relatively high temperature in the cylinder and the appropriate increase in the mixture concentration on the exhaust side are conducive to accelerating the combustion in the early and middle stages. The CA0-10 is shortened, and the CA50 is advanced, which improves the combustion performance under different loads. The brake thermal efficiency (BTE) is increased by 0.53% to 1.27%. Moreover, as the load increases, the increase in BTE becomes more significant. In terms of emission performance, adopting the 16*D0.26 nozzle scheme reduces the amount of methanol in the piston crevice, weakens the crevice effect, and reduces HC emissions by 56.3% to 68.5% under different loads. However, the relatively rich mixture in the combustion chamber on the exhaust side leads to an increase in CO emissions. In conclusion, adopting the high-flow nozzle scheme can lead to a relatively small increase in CO emissions while significantly reducing HC emissions, reducing the liquid film in the cylinder, and obtaining a relatively high BTE. Moreover, it is possible to adjust the injection phase more flexibly under high-load operating conditions.

Zhang, Zhi, Liu, Haifeng, Li, Yongzhi, Chang, Weide, Shu, Zanqiao, Ju, Chengyuan, Ratlamwala, Tahir Abdul Hussain, Yao, Mingfa

Exploring the Future of Sustainable Fuels: Experimental and Predictive Insights on Engine Performance and Emissions Using Algae Biodiesel Blends

2024-01-5250

1/28/2025

This study investigates the potential of biodiesel derived from Azolla algae as an alternative fuel for conventional diesel. The performance and emissions characteristics of various biodiesel blends were evaluated experimentally. The physicochemical properties of pure diesel (D100), and blends with Azolla biodiesel at 5% (BD5), 10% (BD10), 15% (BD15), 20% (BD20), and 100% (B100) were analyzed. It is observed that the amount of fuel consumed is higher at higher loads when fuel is blended with biodiesels. Hydrocarbon emissions were reduced with biodiesel blends at full load and the reduction is higher with increase in blend concentration. A significant difference of 85 ppm NOx was observed between BD20 and D100 at full load. CO emissions decreased with higher biodiesel concentrations, with BD20 resulted less CO emissions than D100, making BD20 a more environmentally viable fuel. Artificial neural networks (ANN) were employed for predictive modeling, achieving approximately 95% accuracy. Pearson’s correlation coefficients (0.9770 to 1.000) and root mean square errors (0.01048 to 0.0804) for all the output parameters indicate the model’s high efficiency and accuracy, closely matching experimental values.

Senthilkumar, D., Murugesan, Sivanesan, Bhadrinath, P., Shamitha, G., Adityasree, R.

Effect of Fuel Chemical Structure on Soot Formation in Sustainable Aviation Fuels

2024-01-4310

11/5/2024

Sustainable Aviation Fuels (SAFs) offer great promises towards decarbonizing the aviation sector. Due to the high safety standards and global scale of the aviation industry, SAFs pose challenges to aircraft engines and combustion processes, which must be thoroughly understood. Soot emissions from aircrafts play a crucial role, acting as ice nuclei and contributing to the formation of contrail cirrus clouds, which, in turn, may account for a substantial portion of the net radiative climate forcing. This study focuses on utilizing detailed kinetic simulations and soot modeling to investigate soot particle generation in aero-engines operating on SAFs. Differences in soot yield were investigated for different fuel components, including n-alkanes, iso-alkanes, cycloalkanes, and aromatics. A 0-D simulation framework was developed and utilized in conjunction with advanced soot models to predict and assess soot processes under conditions relevant to aero-engine combustion. The simulations, conducted under combustion and inert conditions, revealed that aromatic fuels significantly enhance soot yield, exhibiting accelerated growth toward larger aromatics under both combustion and pyrolysis conditions. The results also highlight the necessity for higher gas temperatures for PAHs to grow, in agreement with pyrolysis experiments indicating soot onset temperatures between 1400 and 1500K. Furthermore, the study assessed the influence of precursors on soot formation, challenging the appropriateness of using C2H2 or mono-aromatics as precursors with the tested soot models. The simulation results indicate that such precursors lead to large errors, advocating for the use of larger PAHs as precursor in these soot models, as suggested by the models’ validation space. Finally, this work also explores the impact of fuel structure on soot formation, contributing to ongoing efforts to replace aromatics with cycloalkanes in jet fuels through examining reference fuel blends representative of petroleum-based jet fuel and cycloalkane-based SAFs. The “SAF” blends result in a reduced soot yield compared to the jet fuel surrogate, underscoring SAFs’ capability to diminish emissions in the aviation industry.

Yi, Junghwa, Manin, Julien, Wan, Kevin, Lopez Pintor, Dario, Nguyen, Tuan, Dempsey, Adam

Effects of Fuel Distillation Characteristics on the Performance of Catalyst-Heating Operation in a Medium-Duty Off-Road Diesel Engine

2024-01-4278

11/5/2024

Catalyst heating operation in compression-ignition engines is critical to ensure rapid light-off of exhaust catalysts during cold-start. This is typically achieved by using late post injections for increased exhaust enthalpy, which retardability is constrained by acceptable CO and unburned hydrocarbons emissions, since they are directly emitted through the tailpipe due to the inactivity of the oxidation catalyst at these conditions. Post-injection retardability has shown to be affected by the cetane number of the fuel, but it is unclear how other fuel properties affect the ability to retard the combustion. This study aims to understand the impact of the distillation characteristics of the fuel on the performance of catalyst heating operation and on post-injection retardability. In this study, experiments are performed in a single-cylinder medium-duty diesel engine fueled with three full boiling-range diesel fuels with different distillation curves using a five-injection strategy (two pilot, one main, two post) optimized for catalyst heating operation. The two post-injections are block-shifted to more retarded timings for three different first-post to second-post fuel split ratios and at a constant engine load. Decreasing the volatility of the fuel leads to higher exhaust enthalpy values and lower CO and unburned hydrocarbon emissions. The increase in exhaust enthalpy is caused by an additional fuel requirement to compensate for higher heat losses caused by higher flame-wall interactions with the less volatile fuels. The decrease in CO and unburned hydrocarbon emissions is caused by lower formation of overly-lean regions that do not burn properly using with the less volatile fuels. Thus, low volatility fuels improve the retardability of post injections. Chemical kinetic simulations are performed to better understand autoignition reactivity differences between fuels, concluding that fuel effects are more important for the pilot injections due to the low in-cylinder temperature and high in-cylinder pressure at the time of injection.

Lee, Sanguk, Lopez Pintor, Dario, Cho, Seokwon, Busch, Stephen

Quantifying Environmental and Health Impacts of Conventional Diesel and Methane Diesel RCCI Engine Emissions: A Numerical Analysis

2024-01-4307

11/5/2024

A reactivity-controlled compression ignition (RCCI) engine offers ultralow soot and nitrogen oxide (NOx) emission in addition to higher thermal efficiency than diesel or compression ignition (CI) engines. However, the higher emissions of unburned hydrocarbons (HC) and carbon monoxide (CO) from RCCI engines pose a significant challenge that hinders their adoption in the future automotive sector. Additionally, HC includes several hydrocarbons that harm human health and the environment. This study aims to minimize HC and CO formation and emissions by implementing different injection strategies, including adjustments to spray angle configuration, injection timing, and fuel premixing ratio. Additionally, the study examines how different injection strategies affect the spatial and temporal distribution of HC and CO inside the combustion chamber. To achieve this objective, a numerical investigation is conducted on a single-cylinder diesel engine modified to operate in RCCI mode, utilizing a detailed reaction mechanism with ANSYS FORTE. The reaction mechanism comprises 137 species and 1,022 reactions, using n-heptane and CH4 as fuel surrogates. Initially, the computational model is developed using engine geometry and validated against experimental results for conventional diesel and RCCI modes, after which a parametric investigation is conducted. The results demonstrate that, among injection strategies, the spray configuration has the greatest impact on HC and CO emissions. Narrow spray configuration in RCCI combustion leads to a significant decrease in HC and CO emissions. HC and CO emissions increase with advanced injection timing and a higher fuel premixing ratio. RCCI engines exhibit lower acidification potential and eutrophication potential equivalent emissions compared to conventional diesel engines.

Yadav, Neeraj Kumar, Chandel, Amit Singh, Maurya, Rakesh Kumar, Padhee, Srikant Sekhar

Ionization Based Sensor for Early Detection of Thermal Runaway Events in Lithium-Ion Batteries

2024-01-4326

11/5/2024

Lithium-ion and lithium-metal battery cells are susceptible to a phenomenon known as thermal runaway under failure conditions. Given their widespread use in applications such as electric vehicles, portable electronics, and energy storage systems, early detection of thermal runaway is crucial for ensuring the safety of these battery systems. Thermal runaway entails a rapid escalation in battery cell temperature accompanied by the emission of flammable lithium ions, particulates, electrons, hydrocarbons, and hydrogen gases. These gases pose a significant ignition risk, potentially leading to fires and endangering occupants and bystanders. Therefore, the timely detection of thermal runaway is paramount for ensuring safety in proximity to such battery systems. Traditionally, thermal runaway sensors comprise intricate assemblies of pressure, temperature, and gas sensors, strategically positioned at the pressure relief valve of battery modules. Calibration of all sensors is essential to reliably detect thermal runaway conditions. An alternative method for thermal runaway detection involves the identification of ions and free electrons present in the gases emitted by the battery, utilizing ionization techniques. This paper presents an experimental investigation for the early detection of thermal runaway using a novel ionization sensor. The setup involves the placement of a fully charged battery pouch cell on a heater equipped with thermocouples and cell voltage measurement. The cell is enclosed within a container with a controlled opening to the atmosphere. A detailed analysis of the ionization signal was compared with the thermocouple measurements and battery voltage. In addition, a comparison between sealed and vented pouch cell batteries was made, and the detection of thermal runaway was analyzed. The novel sensor reliably detects early signs of thermal runaway in lithium-ion batteries, often before or during pouch rupture, making it valuable for early warning systems. Its effectiveness across different scenarios highlights its potential for integration into battery management systems to significantly enhance safety protocols.

Mansour, Youssef

HYPERFIRE: A Sub-Scale Non-Reacting Flow Test System

TBMG-51750

10/1/2024

Engineers at NASAs Stennis Space Center have developed the HYdrocarbon Propellants Enabling Reproduction of Flows in Rocket Engines (HYPERFIRE), a sub-scale, non-reacting flow test system. HYPERFIRE uses heated ethane to enable physical simulation of rocket engines powered by a broad range of propellants in an inexpensive, accurate, and simple fashion.

Aerospace - General Requirements for Hydraulic Fuse - Quantity Measuring

AS5466 (Current)

6/24/2024

This specification establishes the design, performance, and test requirements for hydraulic quantity measuring fuses intended to be used for hydraulic circuit protection.

A-6C5 Components Committee

Engine Behavior Analysis on a Conventional Diesel Engine Powered with Blends of Lemon Grass Oil Biodiesel–Diesel Blends

03-17-08-0058

6/14/2024

Fossil fuel usage causes environmental pollution, and fuel depletion, further affecting a country’s economy. Biofuels and diesel-blended fuels are practical alternatives to sustain fossil fuels. This experimental study analyses lemongrass oil’s performance, emissions, and combustion characteristics after blending with diesel. Lemongrass oil is mixed with diesel at 10 (B10), 15 (B15), and 25% (B25) and evaluated using a 5.20 kW direct injection diesel engine. B10 brake thermal efficiency is 36.47%, which is higher than other blends. The B10 displays an 8.73% decrease in brake-specific fuel consumption compared to diesel. An increase in exhaust gas temperature for B10 than diesel is 4.5%. It indicates that higher lemongrass oil blends decrease exhaust gas temperature. The decrease in average carbon monoxide emissions in B10 to diesel is 22.19%. The decrease in hydrocarbon emissions for B10 to diesel is 7.14%. Biodiesel with lemongrass oil increases nitrogen oxide (NOx) because of increased temperature and poor combustion. Apart from NOx emissions, all other parameters of lemongrass oil blends are suitable for practical diesel applications. The significant findings benefit the biodiesel community toward the efficient combustion of biodiesel blends.

Swami Punniakodi, Banumathi Munuswamy, Arumugam, Chelliah, Suyambazhahan, Sivalingam, Senthil, Ramalingam, Balasubramanian, Dhinesh, Papla Venugopal, Inbanaathan, Nguyen, Van Nhanh, Cao, Dao Nam

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