Chemical Engineering › Fluid Flow and Transfer Processes

Advanced Combustion Engine Technologies

Works Count: 96965

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Description

This cluster of papers focuses on the chemical kinetics of combustion processes, including soot formation, internal combustion engines, fuel chemistry, oxidation mechanisms, laminar flame speeds, and emissions from various hydrocarbon and biofuels. It covers a wide range of topics related to the understanding and modeling of combustion reactions in different engine and fuel systems.

Keywords

Combustion; Chemical Kinetics; Soot Formation; Internal Combustion Engines; Fuel Chemistry; Oxidation Mechanism; Laminar Flame Speeds; Hydrocarbon Fuels; Emissions; Biofuels

KIVA-3V: A block-structured KIVA program for engines with vertical or canted valves

1997-07-01

A.A. Amsden

This report describes an extended version of KIVA-3, known as KIVA-3V, that can model any number of vertical or canted valves in the cylinder head of an internal combustion (IC) … This report describes an extended version of KIVA-3, known as KIVA-3V, that can model any number of vertical or canted valves in the cylinder head of an internal combustion (IC) engine. The valves are treated as solid objects that move through the mesh using the familiar snapper technique used for piston motion in KIVA-3. Because the valve motion is modeled exactly, and the valve shapes are as exact as the grid resolution will allow, the accuracy of the valve model is commensurate with that of the rest of the program. Other new features in KIVA-3V include a particle-based liquid wall film model, a new sorting subroutine that is linear in the number of nodes and preserves the original storage sequence, a mixing-controlled turbulent combustion model, and an optional RNG {kappa}-{epsilon} turbulence model. All features and capabilities of the original KIVA-3 have been retained. The grid generator, K3PREP, has been expanded to support the generation of grids with valves, along with the shaping of valve ports and runners. Graphics output options have also been expanded. The report discusses the new features, and includes four examples of grids with vertical and canted valves that are representative of IC engines in use today.

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Active Thermo-Atmosphere Combustion (ATAC) - A New Combustion Process for Internal Combustion Engines

1979-02-01

Shigeru Onishi , Souk Hong Jo , Katsuji Shoda +2 more

A new lean combustion process for internal combustion engines has been developed. This newly devised combustion system, designated as Active Thermo-Atmosphere Combustion (ATAC), differs from conventional gasoline and diesel engine … A new lean combustion process for internal combustion engines has been developed. This newly devised combustion system, designated as Active Thermo-Atmosphere Combustion (ATAC), differs from conventional gasoline and diesel engine combustion processes. ATAC can be applied most easily to two-stroke cycle gasoline engines. Stable combustion can be achieved with lean mixtures at part-throttle operation. With ATAC the fuel consumption and exhaust emissions of two-stroke cycle spark-ignition engines are remarkably improved, and noise and vibration are reduced.

Mechanism of the Smokeless Rich Diesel Combustion by Reducing Temperature

2001-03-05

Kazuhiro Akihama , Yoshiki Takatori , Kazuhisa Inagaki +2 more

Introduction to Internal Combustion Engines

2012-01-01

R. Stone

Notation XV 7.5.1 Firing engine tests 7.5.2Non-firing engine tests 7.5.3Port flow characteristics 7.6 Engine performance and technology 7.7 Concluding remarks 7.8 Questions 8 In-cylinder motion and turbulent combustion 8.1 13.4.6Determination … Notation XV 7.5.1 Firing engine tests 7.5.2Non-firing engine tests 7.5.3Port flow characteristics 7.6 Engine performance and technology 7.7 Concluding remarks 7.8 Questions 8 In-cylinder motion and turbulent combustion 8.1 13.4.6Determination of EGR and exhaust residual (ER) levels 13.4.7 Determination of the air/fuel ratio from exhaust emissions 13.5 Computer-based combustion analysis 13.5.1 Introduction 13.5.2Burn rate analysis 13.5.3Heat release analysis 13.6 Advanced test systems 13.7 Conclusions 13.8 Question

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Modeling the Effects of Drop Drag and Breakup on Fuel Sprays

1993-03-01

Alex B. Liu , Daniel Mather , Rolf D. Reitz

Abstract : Spray models have been evaluated using experimentally measured trajectories and drop sizes of single drops injected into a high relative velocity gas flow. The computations were made using … Abstract : Spray models have been evaluated using experimentally measured trajectories and drop sizes of single drops injected into a high relative velocity gas flow. The computations were made using a modified version of the KIVA-2 code. It was found that the drop drag coefficient and the drop breakup time model constant had to be adjusted in order to match the measurements. Based on these findings, a new drop drag submodel is proposed in which the drop drag coefficient changes dynamically with the flow conditions. The model accounts for the effects of drop distortion and oscillation due to the relative motion between the drop and the gas. The value of the drag coefficient varies between the two limits of that of a rigid sphere (no distortion) and that of a disk (maximum distortion). The modified model was also applied to diesel sprays. The results show that the spray tip penetration is relatively insensitive to the value used for the drop drag coefficient. However, the distribution of drop sizes within sprays is influenced by drop drag. This is due to the fact that changes in drop drag produce changes in the drop-gas relative velocity. This, in turn, causes changes in the spray drop size through the drop breakup and coalescence processes. The changes occur in such a way that the net effect on the spray penetration is small over the tested ranges of conditions. These results emphasize that measurements of spray penetration are not sufficient to test and produce improved spray models. Instead, local measurements of drop size and velocity are needed to develop accurate spray models.

Introduction to Modeling and Control of Internal Combustion Engine Systems

2004-01-01

Lino Guzzella , Christopher H. Onder

A Conceptual Model of DI Diesel Combustion Based on Laser-Sheet Imaging*

1997-02-24

John E. Dec

A Hierarchical and Comparative Kinetic Modeling Study of C<sub>1</sub> − C<sub>2</sub> Hydrocarbon and Oxygenated Fuels

2013-08-17

Wayne K. Metcalfe , Sinéad M. Burke , Syed Sayeed Ahmed +1 more

ABSTRACT A detailed chemical kinetic mechanism has been developed to describe the oxidation of small hydrocarbon and oxygenated hydrocarbon species. The reactivity of these small fuels and intermediates is of … ABSTRACT A detailed chemical kinetic mechanism has been developed to describe the oxidation of small hydrocarbon and oxygenated hydrocarbon species. The reactivity of these small fuels and intermediates is of critical importance in understanding and accurately describing the combustion characteristics, such as ignition delay time, flame speed, and emissions of practical fuels. The chosen rate expressions have been assembled through critical evaluation of the literature, with minimum optimization performed. The mechanism has been validated over a wide range of initial conditions and experimental devices, including flow reactor, shock tube, jet‐stirred reactor, and flame studies. The current mechanism contains accurate kinetic descriptions for saturated and unsaturated hydrocarbons, namely methane, ethane, ethylene, and acetylene, and oxygenated species; formaldehyde, methanol, acetaldehyde, and ethanol.

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A Universally Applicable Equation for the Instantaneous Heat Transfer Coefficient in the Internal Combustion Engine

1967-02-01

Gerhard Woschni

Kinetic modeling of soot formation with detailed chemistry and physics: laminar premixed flames of C2 hydrocarbons

2000-04-01

Jörg Appel , H. Bockhorn , Michael Frenklach

A detailed chemical kinetic model for high temperature ethanol oxidation

1999-01-01

N.M. Marinov

A detailed chemical kinetic model for ethanol oxidation has been developed and validated against a variety of experimental data sets. Laminar flame speed data (obtained from a constant volume bomb … A detailed chemical kinetic model for ethanol oxidation has been developed and validated against a variety of experimental data sets. Laminar flame speed data (obtained from a constant volume bomb and counterflow twin-flame), ignition delay data behind a reflected shock wave, and ethanol oxidation product profiles from a jet-stirred and turbulent flow reactor were used in this computational study. Good agreement was found in modeling of the data sets obtained from the five different experimental systems. The computational results show that high temperature ethanol oxidation exhibits strong sensitivity to the fall-off kinetics of ethanol decomposition, branching ratio selection for C2H5OH + OH ↔ Products, and reactions involving the hydroperoxyl (HO2) radical. The multichanneled ethanol decomposition process is analyzed by RRKM/Master Equation theory, and the results are compared with those obtained from earlier studies. The ten-parameter Troe form is used to define the C2H5OH(+M) ↔ CH3 + CH2OH(+M) rate expression as k∞ = 5.94E23 T−1.68 exp(−45880 K/T) (s−1) ko = 2.88E85 T−18.9 exp(−55317 K/T) (cm3/mol/sec) Fcent = 0.5 exp(−T/200 K) + 0.5 exp(−T/890 K) + exp(−4600 K/T) and the C2H5OH(+M) ↔ C2H4 + H2O(+M) rate expression as k∞ = 2.79E13 T0.09 exp(−33284 K/T) (s−1) ko = 2.57E83 T−18.85 exp(−43509 K/T) (cm3/mol/sec) F cent = 0.3 exp(−T/350 K) + 0.7 exp(−T/800 K) + exp(−3800 K/T) with an applied energy transfer per collision value of <ΔEdown> = 500 cm−1. An empirical branching ratio estimation procedure is presented which determines the temperature dependent branching ratios of the three distinct sites of hydrogen abstraction from ethanol. The calculated branching ratios for C2H5OH + OH, C2H5OH + O, C2H5OH + H, and C2H5OH + CH3 are compared to experimental data. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 183–220, 1999

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Comprehensive H<sub>2</sub>/O<sub>2</sub> kinetic model for high‐pressure combustion

2011-12-06

Michael P. Burke , Marcos Chaos , Yiguang Ju +2 more

Abstract An updated H 2 /O 2 kinetic model based on that of Li et al. ( Int J Chem Kinet 36, 2004, 566–575) is presented and tested against a … Abstract An updated H 2 /O 2 kinetic model based on that of Li et al. ( Int J Chem Kinet 36, 2004, 566–575) is presented and tested against a wide range of combustion targets. The primary motivations of the model revision are to incorporate recent improvements in rate constant treatment and resolve discrepancies between experimental data and predictions using recently published kinetic models in dilute, high‐pressure flames. Attempts are made to identify major remaining sources of uncertainties, in both the reaction rate parameters and the assumptions of the kinetic model, affecting predictions of relevant combustion behavior. With regard to model parameters, present uncertainties in the temperature and pressure dependence of rate constants for HO 2 formation and consumption reactions are demonstrated to substantially affect predictive capabilities at high‐pressure, low‐temperature conditions. With regard to model assumptions, calculations are performed to investigate several reactions/processes that have not received much attention previously. Results from ab initio calculations and modeling studies imply that inclusion of H + HO 2 = H 2 O + O in the kinetic model might be warranted, though further studies are necessary to ascertain its role in combustion modeling. In addition, it appears that characterization of nonlinear bath‐gas mixture rule behavior for H + O 2 (+ M) = HO 2 (+ M) in multicomponent bath gases might be necessary to predict high‐pressure flame speeds within ∼15%. The updated model is tested against all of the previous validation targets considered by Li et al. as well as new targets from a number of recent studies. Special attention is devoted to establishing a context for evaluating model performance against experimental data by careful consideration of uncertainties in measurements, initial conditions, and physical model assumptions. For example, ignition delay times in shock tubes are shown to be sensitive to potential impurity effects, which have been suggested to accelerate early radical pool growth in shock tube speciation studies. In addition, speciation predictions in burner‐stabilized flames are found to be more sensitive to uncertainties in experimental boundary conditions than to uncertainties in kinetics and transport. Predictions using the present model adequately reproduce previous validation targets and show substantially improved agreement against recent high‐pressure flame speed and shock tube speciation measurements. Comparisons of predictions of several other kinetic models with the experimental data for nearly the entire validation set used here are also provided in the Supporting Information. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 44: 444–474, 2012

Alcohol combustion chemistry

2014-06-16

S. Mani Sarathy , Patrick Oßwald , Nils Hansen +1 more

Kinetic modeling of gasoline surrogate components and mixtures under engine conditions

2010-08-20

Marco Mehl , William J. Pitz , Charles K. Westbrook +1 more

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Turbulence Modeling of Internal Combustion Engines Using RNG κ-ε Models

1995-01-01

Zhiyu Han , Rolf D. Reitz

Abstract The RNG κ-ε turbulence model derived by Yakhot and Orszag (1986) based on the Renormalization Group theory has been modified and applied to variable-density engine flows in the present … Abstract The RNG κ-ε turbulence model derived by Yakhot and Orszag (1986) based on the Renormalization Group theory has been modified and applied to variable-density engine flows in the present study. The original RNG-based turbulence transport approximations were developed formally for an incompressible flow. In order to account for flow compressibility the RNG ε-equation is modified and closed through an isotropic rapid distortion analysis. Computations were made of engine compressing/expanding flows and the results were compared with available experimental observations in a production diesel engine geometry. The modified RNG κ-ε model was also applied to diesel spray combustion computations. It is shown that the use of the RNG model is warranted for spray combustion modeling since the ratio of the turbulent to mean-strain time scales is appreciable due to spray-generated mean flow gradients, and the model introduces a term to account for these effects. Large scale flow structures are predicted which are affected by the spray and the squish and are consistent with endoscope combustion images. The effects of flow compressibility on both non-reacting compressing/expanding flows and reacting flows are discussed. It is concluded that predicted combustion parameters, particularly, soot emissions, are significantly influenced by the treatment of flow compressibility in the turbulence model. Key Words: Turbulence modelingrenormatization group κ-εcompressibilityinternal combustion enginesspray combustionpollutant emissions

The hydrogen-fueled internal combustion engine: a technical review

2006-01-31

Christopher White , Richard R. Steeper , Andrew E. Lutz

A comprehensive modeling study of hydrogen oxidation

2004-08-30

Marcus Ó Conaire , Henry J. Curran , John M. Simmie +2 more

Abstract A detailed kinetic mechanism has been developed to simulate the combustion of H 2 /O 2 mixtures, over a wide range of temperatures, pressures, and equivalence ratios. Over the … Abstract A detailed kinetic mechanism has been developed to simulate the combustion of H 2 /O 2 mixtures, over a wide range of temperatures, pressures, and equivalence ratios. Over the series of experiments numerically investigated, the temperature ranged from 298 to 2700 K, the pressure from 0.05 to 87 atm, and the equivalence ratios from 0.2 to 6. Ignition delay times, flame speeds, and species composition data provide for a stringent test of the chemical kinetic mechanism, all of which are simulated in the current study with varying success. A sensitivity analysis was carried out to determine which reactions were dominating the H 2 /O 2 system at particular conditions of pressure, temperature, and fuel/oxygen/diluent ratios. Overall, good agreement was observed between the model and the wide range of experiments simulated. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 603–622, 2004

A directed relation graph method for mechanism reduction

2005-01-01

Tianfeng Lu , Chung K. Law

Chemical kinetics of hydrocarbon ignition in practical combustion systems

2000-01-01

Charles K. Westbrook

Ethanol?diesel fuel blends ?? a review

2004-06-17

Anca Daniela Hansen

Formation of polycyclic aromatic hydrocarbons and their growth to soot—a review of chemical reaction pathways

2000-08-01

Hanz Richter , Jack B. Howard

The potential of di-methyl ether (DME) as an alternative fuel for compression-ignition engines: A review

2007-07-17

C. Arcoumanis , Choongsik Bae , Roy J. Crookes +1 more

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Progress and recent trends in homogeneous charge compression ignition (HCCI) engines

2009-06-22

Mingfa Yao , Zhaolei Zheng , Haifeng Liu

MODELING SPRAY ATOMIZATION WITH THE KELVIN-HELMHOLTZ/RAYLEIGH-TAYLOR HYBRID MODEL

1999-01-01

Rolf D. Reitz , Jennifer C. Beale

An improved spray atomization model is presented for use in both diesel and gasoline spray computations. The KH-RT hybrid atomization model consists of two distinct steps: primary and secondary breakup. … An improved spray atomization model is presented for use in both diesel and gasoline spray computations. The KH-RT hybrid atomization model consists of two distinct steps: primary and secondary breakup. The Kelvin-Helmholtz (KH) instability model was used to predict the primary breakup of the intact liquid core of a diesel jet. The secondary breakup of the individual drops was modeled with the Kelvin-Helmholtz model in conjunction with the Rayleigh-Taylor (RT) accelerative instability model. A modification was made to the KH-RT hybrid model that allowed the RT accelerative instabilities to affect all drops outside the intact liquid core of the jet. In previous implementations, only the drops beyond the breakup length are affected by RT breakup. Furthermore, a Rosin-Rammler distribution was used to specify the sizes of children drops after the RT breakup of a parent drop. The modifications made to the KH-RT hybrid model were found to give satisfactory results and to improve the temperature dependence of the liquid fuel penetration of the diesel sprays significantly. The KH-RT model was also found to predict the spray shape, penetration, and local SMD of hollow-cone sprays as well as previous gasoline spray models based on the TAB model.

A Comprehensive Modeling Study of n-Heptane Oxidation

1998-07-01

Henry J. Curran , P. Gaffuri , William J. Pitz +1 more

Fuel reactivity controlled compression ignition (RCCI): a pathway to controlled high-efficiency clean combustion

2011-06-01

Sage Kokjohn , Reed Hanson , Derek Splitter +1 more

A fuel reactivity controlled compression ignition (RCCI) concept is demonstrated as a promising method to achieve high efficiency – clean combustion. Engine experiments were performed in a heavy-duty test engine … A fuel reactivity controlled compression ignition (RCCI) concept is demonstrated as a promising method to achieve high efficiency – clean combustion. Engine experiments were performed in a heavy-duty test engine over a range of loads. Additionally, RCCI engine experiments were compared to conventional diesel engine experiments. Detailed computational fluid dynamics modelling was then used to explain the experimentally observed trends. Specifically, it was found that RCCI combustion is capable of operating over a wide range of engine loads with near zero levels of NO x and soot, acceptable pressure rise rate and ringing intensity, and very high indicated efficiency. For example, a peak gross indicated efficiency of 56 per cent was observed at 9.3 bar indicated mean effective pressure and 1300 rev/min. The comparison between RCCI and conventional diesel showed a reduction in NO x by three orders of magnitude, a reduction in soot by a factor of six, and an increase in gross indicated efficiency of 16.4 per cent (i.e. 7.9 per cent more of the fuel energy was converted to useful work). The simulation results showed that the improvement in fuel conversion efficiency was due both to reductions in heat transfer losses and improved control over the start- and end-of-combustion.

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Soot processes in compression ignition engines

2007-01-17

Dale R. Tree , Kenth Svensson

Review of high efficiency and clean reactivity controlled compression ignition (RCCI) combustion in internal combustion engines

2014-08-03

Rolf D. Reitz , Ganesh Duraisamy

This article covers key and representative developments in the area of high efficiency and clean internal combustion engines. The main objective is to highlight recent efforts to improve (IC) engine … This article covers key and representative developments in the area of high efficiency and clean internal combustion engines. The main objective is to highlight recent efforts to improve (IC) engine fuel efficiency and combustion. Rising fuel prices and stringent emission mandates have demanded cleaner combustion and increased fuel efficiency from the IC engine. This need for increased efficiency has placed compression ignition (CI) engines in the forefront compared to spark ignition (SI) engines. However, the relatively high emission of oxides of nitrogen (NOx) and particulate matter (PM) emitted by diesel engines increases their cost and raises environmental barriers that have prevented their widespread use in certain markets. The desire to increase IC engine fuel efficiency while simultaneously meeting emissions mandates has thus motivated considerable research. This paper describes recent progress to improve the fuel efficiency of diesel or CI engines through advanced combustion and fuels research. In particular, a dual fuel engine combustion technology called "reactivity controlled compression ignition" (RCCI), which is a variant of Homogeneous Charge Compression Ignition (HCCI), is highlighted, since it provides more efficient control over the combustion process and has the capability to lower fuel use and pollutant emissions. This paper reviews recent RCCI experiments and computational studies performed on light- and heavy-duty engines, and compares results using conventional and alternative fuels (natural gas, ethanol, and biodiesel) with conventional diesel, advanced diesel and HCCI concepts.

Advanced compression-ignition engines—understanding the in-cylinder processes

2008-10-06

John E. Dec

Hierarchical and comparative kinetic modeling of laminar flame speeds of hydrocarbon and oxygenated fuels

2012-04-21

E. Ranzi , Alessio Frassoldati , Roberto Barberena Graña +4 more

A comprehensive detailed chemical kinetic reaction mechanism for combustion of n-alkane hydrocarbons from n-octane to n-hexadecane

2008-09-16

Charles K. Westbrook , William J. Pitz , Olivier Herbinet +2 more

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Kinetic and thermodynamic issues in the formation of aromatic compounds in flames of aliphatic fuels

1992-10-01

James A. Miller , Carl F. Melius

Detailed modeling of soot particle nucleation and growth

1991-01-01

Michael Frenklach , Hai Wang

A detailed kinetic modeling study of aromatics formation in laminar premixed acetylene and ethylene flames

1997-07-01

Hai Wang , Michael Frenklach

Formation of nitric oxide in premixed hydrocarbon flames

1971-01-01

C.P. Fenimore

A comprehensive modeling study of iso-octane oxidation

2002-05-01

Henry J. Curran

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An updated comprehensive kinetic model of hydrogen combustion

2004-08-04

Juan Li , Zhenwei Zhao , Andrei F. Kazakov +1 more

Abstract A comprehensively tested H 2 /O 2 chemical kinetic mechanism based on the work of Mueller et al. 1 and recently published kinetic and thermodynamic information is presented. The … Abstract A comprehensively tested H 2 /O 2 chemical kinetic mechanism based on the work of Mueller et al. 1 and recently published kinetic and thermodynamic information is presented. The revised mechanism is validated against a wide range of experimental conditions, including those found in shock tubes, flow reactors, and laminar premixed flame. Excellent agreement of the model predictions with the experimental observations demonstrates that the mechanism is comprehensive and has good predictive capabilities for different experimental systems, including new results published subsequent to the work of Mueller et al. 1 , particularly high‐pressure laminar flame speed and shock tube ignition results. The reaction H + OH + M is found to be primarily significant only to laminar flame speed propagation predictions at high pressure. All experimental hydrogen flame speed observations can be adequately fit using any of the several transport coefficient estimates presently available in the literature for the hydrogen/oxygen system simply by adjusting the rate parameters for this reaction within their present uncertainties. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 566–575, 2004

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Reaction mechanism of soot formation in flames

2002-02-21

Michael Frenklach

Chemical reactions and physical processes responsible for the formation of polycyclic aromatic hydrocarbons and soot in hydrocarbon flames are reviewed. The discussion is focused on major elements in the present … Chemical reactions and physical processes responsible for the formation of polycyclic aromatic hydrocarbons and soot in hydrocarbon flames are reviewed. The discussion is focused on major elements in the present understanding of the phenomena, clarification of concepts central to the present state of the art, and a summary of new results.

Internal combustion engine fundamentals

1988-10-01

1 Engine Types and Their Operations 2 Engine Design and Operating Parameters 3 Thermochemistry of Fuel-Air Mixtures 4 Properties of Working Fluids 5 Ideal Models of Engine Cycles 6 Gas … 1 Engine Types and Their Operations 2 Engine Design and Operating Parameters 3 Thermochemistry of Fuel-Air Mixtures 4 Properties of Working Fluids 5 Ideal Models of Engine Cycles 6 Gas Exchange Processes 7 SI Engine Fuel Metering and Manifold Phenomena 8 Charge Motion within the Cylinder 9 Combustion in Ignition Engines 10 Combustion in Compression Ignition Engines 11 Pollutant Formation and Control 12 Engine Heat Transfer 13 Engine Friction and Lubrication 14 Modeling Real Engine Flow and Combustion Processes 15 Engine Operating Characteristics Appendixes

Molecular theory of gases and liquids

1955-01-01

William E. Scott

Methanol as a fuel for internal combustion engines

2018-10-16

Sebastian Verhelst , James Turner , Louis Sileghem +1 more

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Science and technology of ammonia combustion

2018-11-10

Hideaki Kobayashi , Akihiro Hayakawa , K.D. Kunkuma A. Somarathne +1 more

This paper focuses on the potential use of ammonia as a carbon-free fuel, and covers recent advances in the development of ammonia combustion technology and its underlying chemistry. Fulfilling the … This paper focuses on the potential use of ammonia as a carbon-free fuel, and covers recent advances in the development of ammonia combustion technology and its underlying chemistry. Fulfilling the COP21 Paris Agreement requires the de-carbonization of energy generation, through utilization of carbon-neutral and overall carbon-free fuels produced from renewable sources. Hydrogen is one of such fuels, which is a potential energy carrier for reducing greenhouse-gas emissions. However, its shipment for long distances and storage for long times present challenges. Ammonia on the other hand, comprises 17.8% of hydrogen by mass and can be produced from renewable hydrogen and nitrogen separated from air. Furthermore, thermal properties of ammonia are similar to those of propane in terms of boiling temperature and condensation pressure, making it attractive as a hydrogen and energy carrier. Ammonia has been produced and utilized for the past 100 years as a fertilizer, chemical raw material, and refrigerant. Ammonia can be used as a fuel but there are several challenges in ammonia combustion, such as low flammability, high NOx emission, and low radiation intensity. Overcoming these challenges requires further research into ammonia flame dynamics and chemistry. This paper discusses recent successful applications of ammonia fuel, in gas turbines, co-fired with pulverize coal, and in industrial furnaces. These applications have been implemented under the Japanese ‘Cross-ministerial Strategic Innovation Promotion Program (SIP): Energy Carriers’. In addition, fundamental aspects of ammonia combustion are discussed including characteristics of laminar premixed flames, counterflow twin-flames, and turbulent premixed flames stabilized by a nozzle burner at high pressure. Furthermore, this paper discusses details of the chemistry of ammonia combustion related to NOx production, processes for reducing NOx, and validation of several ammonia oxidation kinetics models. Finally, LES results for a gas-turbine-like swirl-burner are presented, for the purpose of developing low-NOx single-fuelled ammonia gas turbine combustors.

Hydrogen-fueled internal combustion engines

2009-09-19

Sebastian Verhelst , Thomas Wallner

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Soot formation

1981-01-01

Brian S. Haynes , H. Gg. Wagner

Dynamic Mode Decomposition

2016-11-23

J. Nathan Kutz , Steven L. Brunton , Bingni W. Brunton +1 more

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Automotive spark-ignited direct-injection gasoline engines

1999-10-01

Fuquan Zhao , Ming‐Chia Lai , David L. Harrington

Turbocharging the Internal Combustion Engine

1982-01-01

N. Watson , Mikoláš Janota

<JATS1:p>The Turbocharger was invented a surprisingly long time ago but only relatively recently has it been an accepted component on all but very small diesel engines. Turbocharging technology for single … <JATS1:p>The Turbocharger was invented a surprisingly long time ago but only relatively recently has it been an accepted component on all but very small diesel engines. Turbocharging technology for single cylinder engines is applicable to a variety of current and prospective single cylinder diesel engine markets, including tractors, generators, water pumps, rickshaws, motorcycles, lawn mowers, and landscaping equipment.</JATS1:p>

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Exploration of the effects of flow parameters and hydrogen addition for methane – air laminar flame development and anchoring

2025-06-25

Basel Al Bishtawi , Xinwei Cheng , Manh‐Vu Tran +1 more | Fuel

On the lubricant oil potential to serve as auto-ignition centre in hydrogen engines: reactivity alteration, chemical ignition, and propagation modes

2025-06-25

Elia Distaso , G. Calò , Riccardo Amirante +2 more | Fuel

Enhancing Specific Fuel Consumption Predictions in Compression Ignition Engine: A Taguchi Optimized Neural Network Approach for Diesel and Polymer Based Fuels

2025-06-24

Tushar M. Patel , Maulik A. Modi | Journal of The Institution of Engineers (India) Series C

Effect of hydrogen enrichment strategy on performance, combustion and emission characteristics of dual-fuel diesel engine: recent progress, challenges and opportunities

2025-06-24

Gaurav Sharma , Ashok Kumar Dewangan , Ashok Kumar Yadav +1 more | Journal of Thermal Analysis and Calorimetry

Machine learning tabulation of thermochemistry for the PAH mechanism and applications to laminar and turbulent sooting flames

2025-06-24

Anxiong Liu , Tianjie Ding , Kun Luo | Combustion and Flame

A numerical toolkit for the ignition delay time and ignition probability density predictions based on instantaneous mixing fields in OpenFOAM

2025-06-23

Zhiwei Huang , Chi Zhang , Qifan Zhang | Fuel

Suitability of DME/LPG blends for SI engines: Reactivity and spray characterization through research and motor octane number measurements coupled with optical imaging techniques

2025-06-23

R. J. Churchill , Manav Sharma , Daniel B. Olsen +1 more | Fuel

Minimum Ignition Energy Density of Premixed NH<sub>3</sub>–H<sub>2</sub> Counterflow Flames

2025-06-23

Wenzhao Ma , Qian Wang , Liming Dai +1 more | Energy & Fuels

Impact of oxygen enrichment on ammonia combustion in spark-ignition engines under partial load conditions

2025-06-23

Fabio Anaclerio , Francesco Fornarelli , Jean-Baptiste Masurier +1 more | Fuel

Partially-charged advanced low-temperature combustion in diesel engine: Progress and prospects

2025-06-21

Thanh Tuan Le , Dhinesh Balasubramanian , Lê Anh Tuấn +7 more | Alexandria Engineering Journal

A novel gas turbine performance prediction model incorporating the residual connection and feature engineering methods

2025-06-21

Bo Yu , Wenhe Liu , Daxing Xie +2 more | Energy

Crank-angle-resolved HR-TEM analysis of aggregation process and nanostructure of GDI in-cylinder soot particles

2025-06-20

Tetsuya Aizawa , S. Noguchi , Yudai Hojo +4 more | International Journal of Engine Research

In order to clarify details of the aggregation process of Gasoline Direct Injection (GDI) in-cylinder soot and thus to provide comprehensive quantitative experimental database required for development and validation of … In order to clarify details of the aggregation process of Gasoline Direct Injection (GDI) in-cylinder soot and thus to provide comprehensive quantitative experimental database required for development and validation of the PM/PN prediction models, Diffused Back Illumination (DBI) laser extinction measurements, crank-angle-resolved total in-cylinder gas/particles sampling, filter gravimetry, High-Resolution Transmission Electron Microscopy (HR-TEM) observation, and analysis of morphology and nanostructure of in-cylinder soot particles using a Rapid Compression and Expansion Machine (RCEM) were conducted. Crank-angle-resolved total mass, aggregate size distribution, primary particle size distribution, fractal dimension, nanostructure, and porosity of in-cylinder soot particles were successfully obtained. The in-cylinder soot mass rapidly increased right after the ignition, gradually increased after cylinder pressure peaked, and stabilized around 0.2 mg under the present experimental condition. The amount and size of large aggregates increased with the progress of combustion, soot formation, and growth. The primary soot particle size increased in the early combustion phase and did not exhibit significant change thereafter. The fractal dimension of the aggregates gradually decreased with the progress of combustion, soot formation, and growth. The porosity of soot particles derived from the HR-TEM nanostructure analysis exhibited relatively high value for initially formed young soot particles and decreased with the progress of combustion. Secondary-agglomeration-assisted sampling was found to effectively facilitate the identification of very sparsely scattered young soot particles deposited onto the TEM grids in low-magnification wide-field TEM observations and the selection of primary particles that do not overlap with the lacey carbon on the TEM grid in high-magnification nanostructure observations. The crank-angle-resolved quantitative data on the aggregation process of GDI in-cylinder soot particles obtained in the present study are expected to facilitate the development and validation of PM/PN prediction models.

Mapping ammonia-diesel combustion on a single-cylinder 107 mm bore diesel engine retrofitted for ammonia port-fuel injection

2025-06-20

Scott Curran , Brian Kaul , Daanish Tyrewala | International Journal of Engine Research

Ammonia is garnering significant interest from the international maritime sector as an alternative fuel. It is attractive as a hydrogen carrier and as a fuel because it has a higher … Ammonia is garnering significant interest from the international maritime sector as an alternative fuel. It is attractive as a hydrogen carrier and as a fuel because it has a higher volumetric energy density compared with gaseous or liquid hydrogen, making it easier to store and transport without requiring high pressures or cryogenic storage. Ammonia has significant toxicity concerns, but safe handling procedures have already been established because it is one of the most widely produced chemicals worldwide for use as a fertilizer. Barriers to consuming NH 3 as a fuel in engines include (1) less favorable ignition energy and flame speed compared with conventional fuels; (2) emissions challenges, including potentially high NH 3 , NO X , and N 2 O emissions; and (3) fuel delivery and handling challenges. Although NH 3 has been used to fuel compression-ignition marine engines in limited demonstration projects, technical barriers still exist. The use of NH 3 as a fuel in smaller-bore, high-speed auxiliary engines for large vessels and for smaller inland and coastal marine applications remains unaddressed. This work investigates a late-injection diesel pilot ignition dual-fuel NH 3 strategy using a single-cylinder, high-speed Cummins four-stroke diesel engine platform with a 107 mm bore and 1.1 L displacement per cylinder. The engine was modified for port fuel injection of heated gaseous anhydrous NH 3 . The diesel fuel injection system and the combustion geometry were unmodified to represent a retrofit application, which would minimize additional hardware to maximize diesel fuel displacement with NH 3 . The results show the applicability of a late injection diesel pilot strategy to overcome the challenging fuel properties of NH 3 over the engine operating envelope. Mapping results focusing on emissions are presented, and comparisons are made to a conventional diesel combustion baseline.

Deep transfer learning-based model for real-time prediction of multiple injection rate in common rail system for marine engine

2025-06-20

Xiangdong Lu , Jianhui Zhao , В. А. Марков +1 more | Energy

Thermal and Emission Performance Evaluation of Hydrogen-Enriched Natural Gas-Fired Domestic Condensing Boilers

2025-06-20

Radosław Jankowski , Rafał Ślefarski , Ireneusz Bauma +1 more | Energies

The combustion of gaseous fuels in condensing boilers contributes to the greenhouse gas and toxic compound emissions in exhaust gases. Hydrogen, as a clean energy carrier, could play a key … The combustion of gaseous fuels in condensing boilers contributes to the greenhouse gas and toxic compound emissions in exhaust gases. Hydrogen, as a clean energy carrier, could play a key role in decarbonizing the residential heating sector. However, its significantly different combustion behavior compared to hydrocarbon fuels requires thorough investigation prior to implementation in heating systems. This study presents experimental and theoretical analyses of the co-combustion of natural gas with hydrogen in low-power-output condensing boilers (second and third generation), with hydrogen content of up to 50% by volume. The results show that mixtures of hydrogen and natural gas contribute to increasing heat transfer in boilers through convection and flue gas radiation. They also highlight the benefits of using the heat from the condensation of vapors in the flue gases. Other studies have observed an increase in efficiency of up to 1.6 percentage points compared to natural gas at 50% hydrogen content. Up to a 6% increase in the amount of energy recovered by water vapor condensation was also recorded, while exhaust gas losses did not change significantly. Notably, the addition of hydrogen resulted in a substantial decrease in the emission of nitrogen oxides (NOx) and carbon monoxide (CO). At 50% hydrogen content, NOx emissions decreased several-fold to 2.7 mg/m3, while CO emissions were reduced by a factor of six, reaching 9.9 mg/m3. All measured NOx values remained well below the current regulatory limit for condensing gas boilers, which is 33.5 mg/m3. These results highlight the potential of hydrogen blending as a transitional solution on the path toward cleaner residential heating systems.

Impact of Ammonia Energy Ratio on the Performance of an Ammonia/Diesel Dual-Fuel Direct Injection Engine Across Different Combustion Modes

2025-06-20

Cheng Li , Sheng Yang , Yuqiang Li | Processes

The ammonia energy ratio (AER) is a critical parameter influencing the performance of ammonia/diesel dual-fuel engines. In this study, a numerical simulation was conducted based on a high-pressure dual-fuel (HPDF) … The ammonia energy ratio (AER) is a critical parameter influencing the performance of ammonia/diesel dual-fuel engines. In this study, a numerical simulation was conducted based on a high-pressure dual-fuel (HPDF) direct injection ammonia/diesel engine to investigate the impact of the AER on combustion and emissions under two distinct combustion modes. By adjusting the ammonia start of injection timing (ASOI), the combustion mode was transitioned from diffusion combustion (HPDF1) to partially premixed combustion (HPDF2). The results show that under the HPDF1 mode, a three-stage heat release pattern is observed, and the evolution curves of NO and NO2 exhibit fluctuations similar to the heat release process. As the AER increases, the second heat release stage is suppressed, the high-temperature region narrows, the ignition delay is extended, and the CA10–CA50 interval shortens, leading to a higher maximum pressure rise rate (MPRR) at a high AER. Conversely, in the HPDF2 mode, the combustion process is characterized by a two-stage heat release. With an increasing AER, the high-temperature region expands, the ignition delay and CA10–CA50 interval are prolonged, while the CA50–CA90 interval shortens, and the MPRR becomes the lowest at a high AER. For both combustion modes, total greenhouse gas (GHG) emissions decrease with an increasing AER. However, in the HPDF2 mode with an AER = 95%, N2O accounts for up to 78% of the total GHG emissions. Additionally, a trade-off relationship exists between NOx emissions and indicated thermal efficiency (ITE). When the ASOI is set to −8°CA ATDC, the engine operates in a transitional combustion mode between HPDF1 and HPDF2. At this point, setting the AER to 95% effectively mitigates the trade-off, achieving an ITE of 53.56% with NOx emissions as low as 578 ppm.

Analysis of the Application of Ammonia as a Fuel for a Compression-Ignition Engine

2025-06-19

Wojciech Tutak , Arkadiusz Jamrozik | Energies

Piston engines used for powering automobiles as well as machinery and equipment have traditionally relied on petroleum-derived fuels. Subsequently, renewable fuels began to be used in an effort to reduce … Piston engines used for powering automobiles as well as machinery and equipment have traditionally relied on petroleum-derived fuels. Subsequently, renewable fuels began to be used in an effort to reduce the combustion of hydrocarbon-based fuels and the associated greenhouse effect. Researchers are currently developing technologies aimed at eliminating fuels containing carbon in their molecular structure, which would effectively minimize the emission of carbon oxides into the atmosphere. Ammonia is considered a highly promising carbon-free fuel with broad applicability in energy systems. It serves as an excellent hydrogen carrier (NH3), free from many of the storage and transportation limitations associated with pure hydrogen. Safety concerns regarding the storage and transport of hydrogen make ammonia an increasingly important fuel also due to its larger hydrogen storage capacity. This manuscript investigates the use of ammonia for powering a dual-fuel engine. The results indicate that the addition of ammonia improves engine performance; however, it may also lead to an increase in NOx emissions. Due to the limitations of ammonia as a fuel, approximately 40% of the energy input must still be provided by diesel fuel to achieve optimal engine performance and acceptable NOx emission levels. The presented research findings highlight the significant potential of NH3 as an alternative fuel for compression-ignition engines. Proper control of the injection strategy or the adoption of alternative combustion systems may offer a promising approach to reducing greenhouse gas emissions while maintaining satisfactory engine performance parameters.

Effects of Split Injection Strategies on Evaporation Dynamics and Combustion Performance: Role of First Injection Mass Ratio in Soot and NOx Reduction

2025-06-19

Weiwei Shang , Haizhao Li , Kang Yang +2 more | Energy

Numerical Investigation of System Architecture and Engine Characteristics Effects on Gasoline Compression Ignition (GCI) Hybrid Heavy-Duty Truck Performance

2025-06-19

Minghao Zhao , Hu Wang , Zunqing Zheng +1 more | International Journal of Automotive Technology

Modeling the Thermodynamics of Oxygen-Enriched Combustion in a GE LM6000 Gas Turbine Using CH4/NH3 and CH4/H2

2025-06-19

Laith Mustafa , Rafał Ślefarski , Radosław Jankowski +2 more | Energies

Gas turbines are widely used in power generation due to their reliability, flexibility, and high efficiency. As the energy sector transitions towards low-carbon alternatives, hydrogen and ammonia are emerging as … Gas turbines are widely used in power generation due to their reliability, flexibility, and high efficiency. As the energy sector transitions towards low-carbon alternatives, hydrogen and ammonia are emerging as promising fuels. This study investigates the thermodynamic and combustion performance of a GE LM6000 gas turbine fueled by methane/hydrogen and methane/ammonia fuel blends under varying levels of oxygen enrichment (21%, 30%, and 40% O2 by volume). Steady-state thermodynamic simulations were conducted using Aspen HYSYS, and combustion modeling was performed using ANSYS Chemkin-Pro, assuming a constant thermal input of 102 MW. Results show that increasing hydrogen content significantly raises flame temperature and burning velocity, whereas ammonia reduces both due to its lower reactivity. Net power output and thermal efficiency improved with higher fuel substitution, peaking at 43.46 MW and 42.7% for 100% NH3. However, NOx emissions increased with higher hydrogen content and oxygen enrichment, while NH3 blends exhibit more complex emission trends. The findings highlight the trade-offs between efficiency and emissions in future low-carbon gas turbine systems.

Soot coagulation due to pulsating flow in diesel engine exhaust: a numerical investigation

2025-06-19

Pavan Prakash Duvvuri , Rajesh Shrivastava , Sheshadri Sreedhara | The European Physical Journal Special Topics

Investigating the effect of butanol isomers on combustion and emissions in port injection dual fuel diesel engines: an experimental study

2025-06-18

Mikail Kılınç , Gökhan Öztürk , Müjdat Fırat | PLoS ONE

The present study examines the effects of substituting alternative fuels for diesel fuel and employing a dual fuel approach on diesel engine combustion characteristics and emissions. Various butanol isomers, namely … The present study examines the effects of substituting alternative fuels for diesel fuel and employing a dual fuel approach on diesel engine combustion characteristics and emissions. Various butanol isomers, namely ıso-butanol, n-butanol, tert-butanol, and sec-butanol, were chosen as novelty alternative fuels. In dual fuel combustion strategy, diesel fuel was injected directly into the cylinder, while butanol isomers as a secondary fuel were introduced into the cylinder at the beginning of the intake period using a port injection technique. The tests were repeated for 15%, 30%, and 45% premixing ratios (Rp) of butanol isomers. This study presents detailed combustion parameters and pollutant emission findings produced in diesel engines employing a dual fuel strategy with butanol isomers. In general, an increase within in cylinder pressure and heat release rate was observed. Especially at a premixing ratio of 45%, an increase of 50% within heat release rate was observed. Use of all butanol isomers increased the ignition delay and shortened combustion duration. Brake thermal efficiency remained at acceptable levels, and ringing intensity was below the knock limit. In addition to an increase in CO and HC emissions, NOX emissions were also up at other premixing ratios but declined at 15%. High levels of decreased smoke opacity were recorded. Especially at a premixing ratio of 45% iso-butanol, a decrease up to 90% is remarkable. In conclusion, the combustion characteristics and pollutant emission results obtained from the experimental engine are discussed in detail according to the operating parameters. The obtained findings provide important information about the performance and emission profiles of alternative fuels and dual fuel systems and provide guidance for future research.

Effects of H2O on NH3 combustion in air: A reactive molecular dynamics study

2025-06-18

Tong Li , Jing Wang , Yingshan Hong +3 more | Journal of the Energy Institute

In situ multi-tier auto-ignition detection applied to dual-fuel combustion simulations

2025-06-17

Jorge Salinas , Hemanth Kolla , Martin Rieth +7 more | Combustion and Flame

Towards Intelligent Combustion: A Bibliometric and Machine Learning Analysis of Hydrogen-Fueled Gas Turbines

2025-06-17

Agonga Oyinbonogha Fred | International Journal for Research in Applied Science and Engineering Technology

Thermo-acoustic instability poses significant challenges to the safe and efficient operation of hydrogen-fueled gas turbines, particularly in industrial applications. This study conducts a comprehensive bibliometric analysis to explore research trends, … Thermo-acoustic instability poses significant challenges to the safe and efficient operation of hydrogen-fueled gas turbines, particularly in industrial applications. This study conducts a comprehensive bibliometric analysis to explore research trends, identify gaps, and evaluate predictive modeling opportunities for thermo-acoustic instability in hydrogen combustion systems. Using Scopus and Web of Science data analyzed with Bibliometrix (R-package), the study maps the thematic evolution of key research areas. The findings reveal extensive work on performance optimization, flow dynamics, and combustion propagation, yet limited attention to hydrogen-specific thermo-acoustic instability. Additionally, while numerical simulations and active control mechanisms are well-developed, real-time predictive modeling using machine learning (ML) remains underexplored. To bridge these gaps, this study proposes a hybrid AI-CFD framework incorporating neural networks for enhanced instability prediction and control. The insights gained contribute to advancing hydrogen combustion technologies, enabling safer and more efficient gas turbine operations

Optimization of spray breakup model parameters for predicting fuel spray and film characteristics in gasoline direct injection engines

2025-06-17

Hao-Pin Lien , Diego Bestel , Le Zhao +7 more | International Journal of Engine Research

This study investigated the behavior of gasoline direct injection (GDI) sprays using computational fluid dynamics (CFD). The authors developed an approach to identify optimal spray breakup model parameters by evaluating … This study investigated the behavior of gasoline direct injection (GDI) sprays using computational fluid dynamics (CFD). The authors developed an approach to identify optimal spray breakup model parameters by evaluating an error function across numerous simulations, with the goal of minimizing discrepancies from experimental data. Using the optimal setup, the simulated spray matched well with projected liquid volume distributions, liquid penetration, and spray width measured in a constant-pressure continuous-flow chamber. To further validate the approach, the same setup was tested across various fuels, injectors, and operating conditions. Subsequently, the optimal setup, along with a recently developed spray-wall interaction model, were applied to a direct-injection spark-ignited engine under late-injection conditions to predict and evaluate fuel film formation and evolution at varying engine coolant temperatures. With the centrally mounted injector directing the spray toward the piston, simulations indicated that the spray tends to impinge on the piston surface. The proposed simulation framework also accurately captured the aggregate film area on the piston surface, aligning with previously published experimental results. Moreover, simulations showed that increasing the coolant temperature from cold start conditions (333 K) to warm conditions (363 K) reduced the fuel mass deposited on the piston by roughly 50%. Furthermore, for the spray-guided engine configuration studied in this work, the CFD model predicted minimal film deposition on the spark plug electrodes regardless of the coolant temperatures due to a relatively weak in-cylinder flow during the compression phase.

Research on the Mechanism of Adjusting the Bypass Ratio for an Adaptive Cycle Engine

2025-06-16

Qian Li , Guoping Huang , Chen Xia +1 more | Advances in transdisciplinary engineering

The adaptive cycle engine can maintain good performance in both supersonic and subsonic cruise with a wide adjustment range of bypass ratio. In this paper, the performance model of the … The adaptive cycle engine can maintain good performance in both supersonic and subsonic cruise with a wide adjustment range of bypass ratio. In this paper, the performance model of the adaptive cycle engine was established, using the XA100 as a baseline engine. Based on the performance model, the mass flow rate. The effect of mass flow distribution between the first and second splitters on the specific thrust and specific fuel consumption was analyzed. The results show that under the same bypass ratio, the first split ratio has a more effect on specific thrust than the second split ratio. The first split ratio reduced from 0.6 to 0.1, specific thrust increases by 24.3%. And the second split ratio has a greater effect on specific fuel consumption. The second split ratio increased from 0.1 to 0.5, saving 11.1% on specific fuel consumption. Then, the experimental model of the multistage splitter system (first and second splitters) and FVABI of the ACE was completed. And the experimental results show that the performance of the first and second splitters remain above 0.965 under the different mass-flow-ratio combinations. At the same time, the airflow of the CDFS duct has a stronger adjusting effect on the airflow of the second splitter than that of the first splitter.

Ammonia-Diesel Engines Segmented Modeling Approach and Simplified Combustion model Research

2025-06-16

Guangyuan Li , Run Chen , Xinran Wang +5 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Ammonia-diesel dual-fuel engines can effectively reduce greenhouse gas (GHG) emissions. Aiming at the real-time control requirements of ammonia/diesel dual-fuel engines, this study proposes a segmented real-time … <div class="section abstract"><div class="htmlview paragraph">Ammonia-diesel dual-fuel engines can effectively reduce greenhouse gas (GHG) emissions. Aiming at the real-time control requirements of ammonia/diesel dual-fuel engines, this study proposes a segmented real-time modeling method and a heat release rate model simplification strategy by linearized heat release rate curves. First, the engine working cycle is divided into three parts: intake and exhaust stage, compression and expansion stage, and combustion process. Different simulation steps and modeling strategies are designed to optimize computational efficiency while maintaining the necessary level of accuracy at each stage. Secondly, based on the calibrated heat release rate (HRR) curves, feature points are extracted to construct a simplified linear heat release model. In the absence of calibration data, the characteristic points of the HRR curves are obtained through interpolation. Compared with the commonly used combustion model, the Wiebe model, the proposed simplified model can more easily obtain the parameters required for calibration while maintaining accuracy. Finally, the effectiveness of the model was verified experimentally under various cases. The results showed that the real-time modeling method can keep single-cycle simulation time in 2ms, the prediction deviations of the indicated mean effective pressure (IMEP) under 4% and the peak pressure in the cylinder (<i>p</i><sub>max</sub>) deviations are less than 2%, and the deviations of specific combustion angle (CA10, CA50, CA90) are controlled within 1°crankshaft angle (CA). It provides a model basis for the real-time control of ammonia diesel engines and is of great value in promoting the engineering application of ammonia fuel in transportation fields such as ship power systems.</div></div>

Comparison of Methanol and Gasoline Fuel Spray Vaporization Using Direct-Injection Technology

2025-06-16

Kevin Wan , Rafael Clemente Mallada , Zachary D. Buen +4 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Considering the large opportunity to reduce net lifecycle carbon emissions through the use of renewable methanol, we address spray technologies needed to overcome the challenge of … <div class="section abstract"><div class="htmlview paragraph">Considering the large opportunity to reduce net lifecycle carbon emissions through the use of renewable methanol, we address spray technologies needed to overcome the challenge of wall wetting and poor vaporization for methanol and the need for improved computational modeling of these processes. High-speed extinction imaging followed by computed tomography reconstruction is utilized to provide three-dimensional liquid volume fraction for reference fuel injectors, to be used for model validation activities. The first injector is the symmetric 8-hole Spray M injector for the Engine Combustion Network, and the second injector is an asymmetric 6-hole injector designed for lateral-cylinder mounting. The degree of plume interaction and vaporization are characterized at representative injection conditions, showing substantially higher concentrations of liquid for methanol than gasoline even with preheated fuel temperatures (90 degrees C). In light of higher injected mass requirements for methanol sprays in combustion applications due to its lower chemical enthalpy, an elevated injection pressure is explored to visualize their effects on spray morphology and improve our understanding of the accelerated evaporation from higher injection pressure. Differences between using collimated and diffuse lighting for extinction measurements are discussed along with the uncertainties associated with each diagnostic. The collimated light source provides higher fidelity optical thickness measurements compared to the diffuse light source but suffers from interference from vapor-phase beam steering. The beam steering effects creates difficulty on the determining the liquid boundary but has negligible impact on the total measured extinction at mild conditions.</div></div>

Experimental Analysis of Performance and Durability Using Ethanol 27% Fuel Blend in a Turbocharged Gasoline Direct Injection Engine

2025-06-16

D R Vigneshwar , Vijayabaskar Bhakthavachalu , M. Muralidharan | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">India aims to achieve 20% ethanol blending (E20) in petrol by 2025 under its National Biofuels Policy to reduce carbon emissions, enhance energy security, and support … <div class="section abstract"><div class="htmlview paragraph">India aims to achieve 20% ethanol blending (E20) in petrol by 2025 under its National Biofuels Policy to reduce carbon emissions, enhance energy security, and support the agricultural economy. Building on this, E27 (27% ethanol in gasoline) is being evaluated as an advanced mid-level blend to further lower greenhouse gas emissions and reduce reliance on fossil fuels. This study investigates the performance, emissions, and combustion characteristics of a turbocharged gasoline direct injection (TGDI) engine using E27 fuel over 20,000 km in real-world driving conditions, as part of a broader research program accumulating over 100,000 km across multiple vehicle categories. Key findings indicate that E27 achieves an optimal balance of emissions reduction and performance, with NOx and THC emissions decreasing by 12% and 5%, respectively, compared to E10, while CO and CO₂ levels remained stable, reflecting ethanol’s oxygenation effect and lower carbon intensity. Power output and acceleration improved slightly due to ethanol’s higher-octane rating and improved combustion efficiency.</div><div class="htmlview paragraph">Oil degradation and wear remained within acceptable limits, confirming E27's suitability for regular use without requiring engine modifications. The findings suggest that E27 blended fuel has potential and can significant future ethanol adoption strategy, which will also supporting its 2030 carbon reduction targets. Further research should focus on optimizing calibration in engine for different ethanol blends as the current study has focused on E10 compliant vehicle’s long-term durability, and performance of the with higher fuel blends aligning with real time usage pattern.</div></div>

“A Comparative Assessment of Port Fuel Injection and Direct Injection of Hydrogen in Internal Combustion Engines: Performance, Efficiency, and Emissions”

2025-06-16

Sukh Das Ahirwar , Naveen Kumar | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">With the transition toward low-carbon fuel-based transportation systems, hydrogen is becoming increasingly promising as a sustainable internal combustion engine (ICE) fuel. There are two pathways for … <div class="section abstract"><div class="htmlview paragraph">With the transition toward low-carbon fuel-based transportation systems, hydrogen is becoming increasingly promising as a sustainable internal combustion engine (ICE) fuel. There are two pathways for introducing hydrogen: Port Fuel Injection (PFI) and Direct Injection (DI) in an engine, which greatly affect performance, efficiency, and emissions.</div><div class="htmlview paragraph">In the Port Fuel Injection (PFI), hydrogen is introduced into the intake manifold and mixed with air before reaching the combustion chamber. This approach is preferred due to its affordability, ease of use, and compatibility with current engine configurations. Because of PFI's more uniform air-fuel mixture, combustion is smoother, and NOx emissions are reduced. On the other hand, it raises the possibility of pre-ignition, particularly when engine loads are high, and a decrease in volumetric efficiency due to a reduction in the volume of intake air as hydrogen replaces it.</div><div class="htmlview paragraph">Direct injection gives exact control over the timing and volume of fuel injected by delivering hydrogen straight into the combustion chamber. This method increases power output, thermal management, and combustion efficiency. Injecting hydrogen closer to the top dead center (TDC) decreases premature ignition. DI also lowers the danger of pre-ignition and knock. Despite these benefits, DI systems are more expensive and complicated, requiring precise control mechanisms and cutting-edge injector technology. The study examines through comparative assessment of the two introduction mechanisms for a country like India and suggests that although DI is better suited for high-performance engines, providing greater efficiency and power, with extra complexity, PFI is favorable for cost-sensitive applications where simplicity and emission reduction are prioritized.</div></div>

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

2025-06-16

Jinru Liu , Yoshiaki Yamazaki , Yusuke Otaki +3 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">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 … <div class="section abstract"><div class="htmlview paragraph">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.</div></div>

Numerical Investigation into the Combustion and Emission Characteristics of Ammonia Direct Injection Mechanism

2025-06-16

Ardhika Setiawan , Ocktaeck Lim | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">The effects of diesel and the ammonia ratio on the emissions and combustion characteristics of ammonia utilized in AMMONIA direct injection (AMMONIA-Di) engines were investigated through … <div class="section abstract"><div class="htmlview paragraph">The effects of diesel and the ammonia ratio on the emissions and combustion characteristics of ammonia utilized in AMMONIA direct injection (AMMONIA-Di) engines were investigated through experimental and numerical investigations. A rapid compression expansion machine (RCEM) modified to facilitate the dual direct injection fuel (diesel-ammonia) - compression ignition (CI) method was used to conduct the experiment. A compression ratio (CR) of 19 and an ammonia energy percentage ranging from 10% to 90% were used in the experiment. Changes were made to the start of injection (SOI) from 0o to 40<sup>o</sup> before top dead center (BTDC) in order to find the best auto-ignition properties of ammonia. In order to facilitate auto-ignition, the diesel’s SOI was maintained at 10<sup>o</sup> BTDC. Computational fluid dynamics (CFD) modeling was used to establish the detailed emission propagation during the combustion process. During the expansion step, ammonia goes through a second stage of combustion, demonstrating that the fuel cannot burn entirely during the initial auto-ignition process. Emissions of CO2, HC, and NOx rise when direct injection CI engines use up to 50% ammonia. When SOI is applied to ammonia at 0 and 40 BTDC with an ammonia energy percentage higher than 50%, the emissions vary significantly, indicating poor combustion quality that encourages the production of emissions.</div></div>

Development of Simple Models for Performance Estimation of a Spark Ignition Engine Fueled with Ammonia and Hydrogen

2025-06-16

A. Ichikawa , Yumiko Ogura , Kazuki Yanaoka +3 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">In engine development, it is needed to investigate engine performance under a lot of conditions. This is called the adaptability test, and it takes a lot … <div class="section abstract"><div class="htmlview paragraph">In engine development, it is needed to investigate engine performance under a lot of conditions. This is called the adaptability test, and it takes a lot of times, money, and manpower. Therefore, decreasing the test is aspired and constructing models that estimate the engine performance is effective for early adoption of ammonia engines. In this research, factors determining the thermal efficiency of a spark ignition engine fueled with ammonia/hydrogen mixtures were investigated and two simple models to estimate the performance were constructed. A diesel based four-stroke single-cylinder spark ignition engine with a displacement volume of 412 cm<sup>3</sup> was used. Different compression ratios <i>ε</i> and two pistons with different squish areas were used. Experiments were conducted for total equivalence ratio of 1.0, while changing the LHV (lower heating value) ratio of ammonia and hydrogen. It is shown that higher compression ratio and larger squish velocity expanded the stable operation range of the engine. For high compression ratio with high squish piston, operation with pure ammonia was possible. The indicated thermal efficiency was expressed as a product of four factors; (i) the effect of compression ratio and specific heat ratio, (ii) the effect of change in molar number, (iii) the effect of degree of constant volume, and (iv) the combustion efficiency. Also, the indicated mean effective pressure was expressed as a product of four factors mentioned above and (v) the input heat. The model reproduced the measured indicated thermal efficiency and the measured indicated mean effective pressure in standard deviation of 0.03.</div></div>

Decarbonisation of GDI Engines Utilising On-Board Hydrogen Production in an Improved Design Thermochemical Exhaust-Assisted Fuel Reformer

2025-06-16

Seung Woo Lee , Ammar Wahbi , J.M. Herreros +3 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Engine intake charge enrichment with hydrogen (H<sub>2</sub>) is one way to enhance engine thermal efficiency and decrease pollutant emissions while replacing carbon-based fuel. Waste energy from … <div class="section abstract"><div class="htmlview paragraph">Engine intake charge enrichment with hydrogen (H<sub>2</sub>) is one way to enhance engine thermal efficiency and decrease pollutant emissions while replacing carbon-based fuel. Waste energy from hot exhaust gas can be thermochemically recovered as hydrogen in catalytic exhaust gas fuel reforming, which can then be used in combustion. This study focuses on tailoring the design of the fuel reformer, including the catalyst chemistry and coating on ceramic and metallic structures, to benefit the whole system’s fuel economy and decrease engine out emissions. The main reformer improvements focused on exhaust flow management and interaction with the engine's after-treatment system, while the final stage focused on the reformer's internal design structure. The new design iteration enabled hydrogen production improvements between 78% and 86% in the critical exhaust gas temperature range of 410°C to 520°C with gas hourly space velocities (GHSVs) in highly demanding engine operating conditions ranging from 16,000 h<sup>-1</sup> to 81,000 h<sup>-1</sup>. The integration of the new fuel reformer with a modern, turbocharged, 2.0 L Hyundai GDI engine raises the fuel efficiency through a combination of higher exhaust energy recovery, improved engine thermal efficiency, and enhanced combustion at highly dilute operation. The engine fuel economy at nine engine speed and torque operating conditions was improved from around 0.5% to 7.88%, with an average of 4.62%.</div></div>

Endoscopic Imaging of Split-Injected Gas Jet Developments in a Multi-Cylinder Hydrogen Low-Pressure Direct-Injection Spark-Ignition Engine

2025-06-16

ChengHua Zhang , Dongchan Kim , Sanghoon Kook +1 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Split injection is widely used in conventional spark ignition engines to control mixture formation. To utilise split injection in a hydrogen direct injection engine, it is … <div class="section abstract"><div class="htmlview paragraph">Split injection is widely used in conventional spark ignition engines to control mixture formation. To utilise split injection in a hydrogen direct injection engine, it is important to understand gas jet development and its variations with injection timing. This is because prolonged duration of gaseous fuel injection is required due to lower energy per volume than that of the liquid fuel, which causes complex jet-tumble interactions. The ambient air pressure and density during the gas injection also changes depending on the injection timing, adding more complexity. This study performs endoscopic high-speed imaging of gas jet laser shadowgraph in an inline four-cylinder low-pressure direct-injection spark ignition (H<sub>2</sub>LPDI) engine equipped with a side-mounted, outward opening pintle nozzle injector. Due to safety concern and its known similarity in macroscopic jet developments, helium was used as an alternative gas to hydrogen. The results showed that the gas jet development changes greatly with the split injection timing selected with respect to the intake valve closure (IVC). For pre-IVC split injection, the first jet and second jet exhibited a very similar jet structure with statistically identical spreading angle and mixture centroid because both injections occurred at low air density conditions. However, the first injection showed a higher penetration rate and jet mixing rate, suggesting a complex interplay with the intake air flow. For post-IVC split injection, the second jet showed a narrower spreading angle due to lifted lower part of the jet, suggesting a strong influence of tumble flow. As the split injection was executed after the IVC, the developing tumble flow significantly accelerated jet penetration for the first injection. However, by the time that the second injection was executed, the tumble flow structure became well defined to hinder the second jet penetration. Indeed, the mixture centroid position was more lifted for the second jet evidencing the significant influence of developing tumble flow.</div></div>

Evaluation of Jet Fuels on Thermal Efficiency, NO <sub>X</sub> Emissions, Particulate Matter, and Particle Size Distribution in a Heavy-Duty Compression Ignition Engine

2025-06-16

Khanh Cung , Niranjan Miganakallu Narasimhamurthy , Imad Khalek +1 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Alternative fuels such as Fischer-Tropsch Synthesized Paraffinic Kerosene (FT-SPK) and Catalytic Hydrothermal Conversion Jet (CHCJ) are among the important sustainable aviation fuels (SAFs) for future transportation. … <div class="section abstract"><div class="htmlview paragraph">Alternative fuels such as Fischer-Tropsch Synthesized Paraffinic Kerosene (FT-SPK) and Catalytic Hydrothermal Conversion Jet (CHCJ) are among the important sustainable aviation fuels (SAFs) for future transportation. However, these alternative fuels often vary in their characteristics, depending on their feedstock and fuel production processes. Therefore, a detailed analysis of these alternative fuels' combustion, emissions, and efficiency must be performed under controlled experiments to understand the impact of fuel properties and operating conditions.</div><div class="htmlview paragraph">This study used a single-cylinder research engine (SCE) with a compression ratio of 17:1. Extensive operating conditions were performed to determine the effect of each fuel on the engine performance, which can be fundamentally understood by fuel properties (e.g., cetane number, heat of combustion, and density) in comparison with Jet-A fuel. The experimental setup includes high-speed data acquisition for combustion analysis and gaseous and solid emissions benches for nitrogen oxides (NO<sub>X</sub>).</div><div class="htmlview paragraph">Results suggested that an engine control management (ECM) strategy can potentially optimize the performance of these alternative jet fuels by compensating for differences in their fuel properties. This study aims to provide insights for future work on exploring different SAF fuels that are more environmentally friendly while meeting the required performance.</div></div>

Hydrogen Jet Characteristics of an Outward-Opening Injector Based on Schlieren Imaging

2025-06-16

Chaoqun Hu , Longbiao Hu , Haie Chen +3 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Hydrogen was considered as a promising carbon-free fuel for future society. The application of hydrogen in internal combustion engines has drawn more and more attention. Jet … <div class="section abstract"><div class="htmlview paragraph">Hydrogen was considered as a promising carbon-free fuel for future society. The application of hydrogen in internal combustion engines has drawn more and more attention. Jet performance of hydrogen injection plays a crucial role in characteristics of the hydrogen fuelled engines, in terms of mixture preparation, combustion and heat release in cylinder. In this research, an outward-opening injector was developed for hydrogen direct-injection applications. The jet performance was studied using high-speed schlieren imaging in a constant volume chamber and the effects of injection and ambient pressures on jet characteristics were investigated. The results show that, the hydrogen jet exhibits a conical structure in the near-field and overall presents a bell-shaped appearance under relatively low ambient pressure, which differs from the irregular structure under relatively high ambient pressure. The pressure ratio, defined as the ratio of injection pressure to chamber pressure, significantly influences the jet characteristics. The increase in the pressure ratio leads to greater axial and radial penetration of the jet, and an increase in the cross-sectional area. The penetration constant of outward-opening injector gas jets is 1.10 ± 0.02 at a pressure ratio ranging from 2 to 10. Separately, elevating the injection pressure enhances its mass flow and improves mixture formation. While increasing the chamber pressure hinders the development and expansion of the jet, resulting in a reduction in the jet entrainment rate.</div></div>

Evaluating the Impact of Displacing Injected Gasoline with Aspirated Ammonia in a Direct Injection Spark Ignition Engine

2025-06-16

Annaniya Mitchell Sivaranjitham , Paul Hellier , Nicos Ladommatos +2 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Replacing fossil fuels with renewable ammonia could provide a crucial step towards the decarbonisation of transport sectors. However, many challenges remain in utilising ammonia within combustion … <div class="section abstract"><div class="htmlview paragraph">Replacing fossil fuels with renewable ammonia could provide a crucial step towards the decarbonisation of transport sectors. However, many challenges remain in utilising ammonia within combustion systems: the volumetric energy density of ammonia is significantly lower than that of gasoline, exposure to ammonia (including ammonia slip) can be detrimental to human health, and the production of emissions, including unregulated emissions (such as N<sub>2</sub>O), from ammonia combustion can be catastrophic for the environment if not treated appropriately. Therefore, there is a need to determine the efficacy of ammonia as a fuel for internal combustion engines and the impact on the efficiency of energy release and the resulting exhaust emissions. A modern spark ignition engine was modified such that ammonia was aspirated through the engine intake air to incrementally displace engine gasoline and maintain a constant work output. It was found that displacing the fuel energy supplied by direct injected gasoline with premixed ammonia by 10% to 40% on an engine work performed basis decreased the peak HRR (heat release rate) and delayed combustion. Spark timing was also advanced to up to 20 CAD BTDC (crank angle degrees before top dead centre) for fuel blends incorporating up to 40% ammonia to allow for optimal conversion of chemical energy to useful work. The corresponding exhaust emissions analysis showed a linear decrease in CO<sub>2</sub>, however, an exponential decrease in CO as the proportion of ammonia increased. Additionally observed was an initial increase in unburnt hydrocarbons followed by a decrease as peak HRR decreased. However, a clear effect of ammonia level on NO<sub>x</sub> emissions was not apparent.</div></div>

Research on Combustion Characteristics of Flash-Boiling Spray in Cylinders Based on Machine Learning Methods

2025-06-16

Weixuan Zhang , Muhammad Shahbaz , Mingli Cui +2 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">With the increasing number of vehicles in operation, exhaust emissions from engines have exerted negative impacts on ecological environments, prompting researchers to actively pursue cleaner and … <div class="section abstract"><div class="htmlview paragraph">With the increasing number of vehicles in operation, exhaust emissions from engines have exerted negative impacts on ecological environments, prompting researchers to actively pursue cleaner and more efficient in-cylinder combustion strategies. Flash-boiling spray technology, capable of generating superior fuel atomization under relatively low injection pressures, has emerged as a promising approach for achieving performance breakthroughs in gasoline direct injection (GDI) engines. While current research primarily focuses on morphological characterization and mechanistic analysis of flash-boiling spray, there remains insufficient understanding of flame development characteristics under flash boiling spray conditions within engine cylinders. This study systematically investigates the combustion characteristics of TPRF and PRF fuels under both subcooled and flash-boiling spray conditions through the integration of image processing and machine learning methodologies. Experimental investigations were conducted on an optically accessible GDI engine, with fuel temperatures maintained at 25°C (subcooled) and 180°C (flash-boiling). Machine learning-based analysis of in-cylinder flame features revealed that critical combustion characteristics can be effectively extracted through correlation matrices and Gini importance parameters, providing quantitative references for manual interpretation of flame development processes. Further comparative analysis demonstrated that subcooled conditions exhibited higher fractal dimensions and marginally faster combustion rates, while flash-boiling sprays significantly enhanced fuel-air mixing homogeneity, suppressed the formation of diffusion flames, and notably reduced aggregated soot particles.</div></div>

Analysis of Combustion Characteristics of a Small 2-Stroke Opposed Piston Engine Using an Optically Accessible Engine and Numerical Analysis

2025-06-16

Yoshiaki Yamazaki , Shigetaka Watanabe , Ikumi Okawara +3 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">As global warming becomes more serious, decarbonization of internal combustion engines, which emit a large amount of carbon dioxide, is being promoted. It is predicted that … <div class="section abstract"><div class="htmlview paragraph">As global warming becomes more serious, decarbonization of internal combustion engines, which emit a large amount of carbon dioxide, is being promoted. It is predicted that many vehicles will still be equipped with engines in 2035, and a variety of powertrains will be required in the future. Therefore, we focused on the opposed-piston engine as an internal combustion engine specialized for power generation applications. The opposed-piston engine is characterized by its light weight due to the absence of a cylinder head, low S/V ratio due to the ultra-long stroke, reduced cooling loss due to the long stroke, and reduced vibration due to the offsetting of the reciprocating inertial forces of the left and right pistons. We believe that the engine for power generation can achieve the required high efficiency operation and vibration reduction. Therefore, in this study, combustion analysis of a two-stroke opposed-piston engine with features of low vibration, high efficiency, and high output was conducted using numerical analysis to solve the vibration problem, which is a demerit of engines for power generation, and to further improve thermal efficiency. In this study, a prototype opposed-piston engine with a displacement of 126.6 [cc] was built and used as an experimental device, but it is difficult to visualize the inside of a cylinder of an opposed-piston engine. Therefore, an experiment was conducted using a 63.3[cc] an optically accessible single-cylinder engine with the same bore and half the displacement and stroke, and the results were compared with the numerical analysis results of the an optically accessible single-cylinder engine, and the validity of the numerical analysis was confirmed. Therefore, we considered that the combustion analysis of an opposed-piston engine was also valid, and we conducted a combustion analysis of an opposed-piston engine using CONVERGE.</div></div>

Flame Developments of Pilot Diesel Ignited Hydrogen Jet in an Optical Dual Direct Injection Engine

2025-06-16

Alan Heaton , Qing Nian Chan , Sanghoon Kook | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">This study aims to characterise the flame development for hydrogen-diesel dual direct injection (H2DDI) in an optically accessible heavy-duty engine through high-speed imaging of the natural … <div class="section abstract"><div class="htmlview paragraph">This study aims to characterise the flame development for hydrogen-diesel dual direct injection (H2DDI) in an optically accessible heavy-duty engine through high-speed imaging of the natural combustion luminosity. A single hole, side mounted injector was used to inject H<sub>2</sub> at 35 MPa in addition to a centrally mounted eight-hole diesel injector providing the ignition source for the H2. Firstly, the diesel pilot flame was examined without H<sub>2</sub> to establish the combustion characteristics of the pilot flame. The pilot fuel energy was reduced from 1200 J to 120 J until the minimum repeatable diesel flame was found, which showed a flame distribution that transitioned from an initial quasi-steady diesel flame at peak load (1200 J), to a piston bowl wall-centric flame distribution (840 J) and then to an injector centric flame (120 J). The minimum pilot fuel quantity of 120 J was then used to investigate the ignition process of hydrogen main fuel mixtures supplying 90% energy and only 10% energy from diesel. The images showed three distinct stages of flame development. Firstly, the ignition of diesel pilot fuel occurs prior to interaction between the two fuels, as the H<sub>2</sub> requires time to penetrate to the centre of the cylinder where the diesel pilot flame forms. Prior to ignition, the H<sub>2</sub> jet penetrates towards the ignition source whilst it is simultaneously spread clockwise by the swirl flow. The second stage of flame development commences as the ignition of this H<sub>2</sub> jet occurring after a period of interaction with the burnt products of the diesel pilot. Upon ignition, the H<sub>2</sub> flame propagates upstream through the partially premixed H<sub>2</sub> mixture and towards the H<sub>2</sub> injector. Following the initial flame propagation, the combustion rate reduces as the transition into a diffusion mode occurs, <i>i.e.</i> the third stage of the flame development, with continued steady reaction zone growth, aided by the swirl flow. This three-stage ignition and flame development does not change with varied diesel pilot injection timing as evidenced by the flame images with only delayed phasing for later diesel pilot injection timing. However, the diesel pilot flame merges with the newly propagating H<sub>2</sub> flame and thus the later diesel pilot injection timing leads to higher peak flame size and intensity.</div></div>

Design and Optimisation of a Passive Pre-Chamber Ignition System for a Heavy-Duty Hydrogen Engine at Lean Conditions

2025-06-16

Hossein Keshtkar , Yizhuo Feng , Hua Zhao +1 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Strict regulations and legislation for carbon emissions and pollution from heavy-duty engines are pushing towards carbon-free fuels such as hydrogen as a fuel for internal combustion … <div class="section abstract"><div class="htmlview paragraph">Strict regulations and legislation for carbon emissions and pollution from heavy-duty engines are pushing towards carbon-free fuels such as hydrogen as a fuel for internal combustion engines. Moving towards this goal, the engine design needs to fully comply with hydrogen’s unique characteristics to achieve optimum performance and efficiency. One aspect that can potentially improve combustion efficiency and emissions is adopting the pre-chamber ignition strategy in large-bore engines at lean conditions. The pre-chamber is a small cavity, usually 3-6% of the total engine volume, installed on the cylinder head, housing the initial combustion event, which would then inject the turbulent jet into the main chamber via nozzles placed at the bottom of the pre-chamber. This ignition strategy would provide multiple flame fronts into the main chamber, accelerating combustion speed and enhancing engine performance. However, the pre-chamber must be designed specifically for Hydrogen combustion to make the best use of this strategy. In this paper, we aimed to investigate the effects of pre-chamber designs such as pre-chamber dome, pre-chamber volume and nozzle diameter on the combustion development in the pre-chamber and, consequently, the combustion in the main chamber along with the engine performance and efficiency of a 2 L single-cylinder heavy-duty hydrogen engine. The simulations are performed in Star-CD software. This research shows that an optimum pre-chamber configuration can significantly affect engine performance. The nozzle diameter has a non-monotonic effect on the jetting propagation. Specifically, a small nozzle diameter will slow down the flame development inside the pre-chamber, followed by restricting the ejected flame jets, while a wider nozzle diameter will weaken the jet momentum into the main chamber. Further, the results revealed that increasing the pre-chamber volume largely enhanced the performance and combustion development, resulting in significant improvements to overall engine performance. Thus, it is clear that the optimum pre-chamber design configuration could significantly improve thermal efficiency, and the dedicated pre-chamber design is critical to achieving optimal performance.</div></div>

Investigating Lubricants Base Oils Reactivity in Ammonia Engines via Accelerated Aging

2025-06-16

Carole Doncoeur , Lucia Giarracca , Perrine Cologon +1 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">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 … <div class="section abstract"><div class="htmlview paragraph">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.</div><div class="htmlview paragraph">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.</div></div>

Parametric Analysis of Injector Operational Parameters, Charge Dilution, and Intake Valve Opening on In-Cylinder Motion and Flame Development in an Automotive, Lean-Burn, Gasoline Engine with High-Tumble

2025-06-16

James MacDonald , Isaac Ekoto , Donghee Han +1 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">The effect of injection pressure, start of injection (SOI) timing, charge dilution, and valve timing on charge motion and early flame development was investigated for a … <div class="section abstract"><div class="htmlview paragraph">The effect of injection pressure, start of injection (SOI) timing, charge dilution, and valve timing on charge motion and early flame development was investigated for a pre-production automotive gasoline engine. Experiments were performed in a single-cycle optical engine designed to represent the high-tumble (Tumble ratio = 1.8), lean-burn engine. Time-resolved particle image velocimetry (PIV) was used to characterize velocity flow fields throughout the swept volume during the intake and compression strokes. Diffuse back illuminated imaging allowed for visualization and quantification of the injected liquid fuel spray and its interactions with the tumble vortex. Hydroxyl (OH*) chemiluminescence imaging was performed to image spark channel elongation and early flame kernel development.</div><div class="htmlview paragraph">It was observed that an optimal injection timing of 320° before top dead center (bTDC) resulted in attenuation of the tumble motion and an associated reduction in compression flows that shifted the tumble vortex toward the intake valves. These effects were amplified with higher injection pressures or advanced injection timings but muted for lower injection pressures or retarded injection timings. This differs from previous observations with a moderate tumble head (tumble ratio = 1.5), where the optimal injection timing resulted in augmentation of the tumble motion due to the momentum of the injected fuel spray, increasing the compression flows. Chemiluminescence imaging and visualization of the spark behavior of the high-tumble engine revealed that the optimal injection timing produced a highly stretched spark channel that consistently deflected toward the exhaust valves, with the flame kernel rapidly expanding in the recirculation zone at the time of spark, leading to a faster overall flame development in the combustion chamber. Variations of the parameters that increased flow velocities (lower injection pressures and retarded injection timings) resulted in less consistent spark positioning and flame kernel development, as well as a higher chance of observing restrikes of the spark. This is suspected to be why the optimal injection timing for the high-tumble head resulted in the attenuation of the tumble motion and reduced flow velocities compared to the moderate tumble head. These results suggest that it is crucial to balance the interactions between the tumble motion and the fuel spray with the with how the flow affects the quality of the spark channel and early kernel development at the time of spark. The interplay between the bulk flow motion and electrode-generated wake turbulence will be discussed, with experimental data compared to companion large eddy simulation results.</div></div>

Combustion and Emission Characteristics of Marine Ammonia-Diesel Dual Fuel Engine with Micro-Pilot Injector Change

2025-06-16

Ilpum Jang , Cheolwoong Park , Minki Kim +4 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">Recently, as regulations on greenhouse gas emissions have become stricter, driven by global warming, there is increasing interest in engines utilizing environmentally friendly fuels. In this … <div class="section abstract"><div class="htmlview paragraph">Recently, as regulations on greenhouse gas emissions have become stricter, driven by global warming, there is increasing interest in engines utilizing environmentally friendly fuels. In this context, ammonia is attracting attention as a potential alternative to fossil fuels in the future. However, due to its distinct fuel properties compared to conventional fuels, research is being conducted on utilizing diesel as an ignition source for ammonia. In this study, the effects of diesel injector fuel flow rate, and micro-pilot (MP) diesel injection timing on combustion and exhaust emission characteristics were analyzed in a single cylinder 12L marine ammonia-diesel dual-fuel engine. Two types of diesel micro-pilot injectors were tested. The first one was high flow rate micro-pilot injector (HMPI) and the second one was low flow rate micro-pilot injector (LMPI). HMPI injector had 66% more number of fuel injector nozzle hole and 250% larger fuel flow rate. Therefore, HMPI injector could distribute diesel more widely within the combustion chamber in a short injection duration, which led to advantages such as an increased ratio of premixed combustion in diesel, improved oxygen utilization in the combustion cylinder, and enhanced ignitability of ammonia.</div><div class="htmlview paragraph">To maintain a constant energy ratio between ammonia and diesel under steady engine load conditions, the injection durations were adjusted, and MP diesel injection timing was varied in increments of 5 crank angle degrees (CAD) to evaluate performance and emission characteristics. The experimental results showed that HMPI demonstrated higher thermal efficiency and lower unburned NH<sub>3</sub> and N<sub>2</sub>O emission levels compared to LMPI. HMPI also showed improved overall performances under advanced MP diesel injection timing, however, performance of LMPI was also improved under the same conditions due to reduced interference between ammonia and MP diesel injection spray compared to the conditions under delayed MP diesel injection timing.</div></div>

Effects of Injection and Intake Timing on Atomization and Combustion in a Hybrid Gasoline Direct Injection Optical Engine under the Low-Speed Low-Load Condition

2025-06-16

Mingli Cui , Jinhong Fu , Xingjia Man +4 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">With the growing trend of hybridization in modern engines, hybrid gasoline direct injection (GDI) engines are typically designed for high load at BMEP of 6 to … <div class="section abstract"><div class="htmlview paragraph">With the growing trend of hybridization in modern engines, hybrid gasoline direct injection (GDI) engines are typically designed for high load at BMEP of 6 to 10 bar, low-to-mid speed of 2000 to 3000 rpm to achieve optimal fuel economy. However, these engines inevitably operate under low-speed, low-load conditions, such as during engine startup and low-speed cruising, where insufficient intake air often leads to poor air-fuel mixing and weak turbulence, resulting in suboptimal combustion. Adjusting intake and injection timing presents a simple and effective approach to optimizing the combustion process in hybrid GDI engines. In this study, an optical engine with a combustion system geometry identical to that of an advanced hybrid GDI engine was used. The engine featured a compression ratio of 15.0:1 and was equipped with a variable timing camshaft for intake timing control and an electronically controlled system for injection timing. High-speed color imaging, using transparent pistons and cylinder liners, captured the in-cylinder spray development and combustion processes. The interaction between the airflow, spray, and piston was analyzed to better understand its effects on combustion. The results showed that advancing the intake timing, relative to the baseline intake and injection settings, enhanced the interaction between the airflow and the fuel spray, improved flame kernel development and reduced pool fires caused by fuel films on the piston. In contrast, delaying the injection timing reduced pool fires by decreasing spray impingement on the piston; however, the delay prevented proper evaporation of the fuel droplets, causing the formation of a sooty yellow flame on the intake side due to the accumulation of fuel in the tumble region. This study demonstrates that careful tuning of intake and injection timings can optimize in-cylinder combustion, improve fuel-air mixing, and reduce emissions in hybrid GDI engines operating under low-speed, low-load conditions.</div></div>

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

2025-06-16

Chansoo Park , Ilpum Jang , Cheolwoong Park +2 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">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 … <div class="section abstract"><div class="htmlview paragraph">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.</div><div class="htmlview paragraph">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.</div><div class="htmlview paragraph">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.</div></div>

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

2025-06-16

Seungwon Lee , Hyunsoo Kim , Joonsik Hwang +1 more | SAE technical papers on CD-ROM/SAE technical paper series

<div class="section abstract"><div class="htmlview paragraph">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 … <div class="section abstract"><div class="htmlview paragraph">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 (<span class="monospace">λ</span>) 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.</div></div>