To elucidate the complex characteristics of pre-chamber combustion engines, the interaction of the hot gas jets initiated by an active narrow throated pre-chamber with lean premixed CH4/air in a heavy-duty engine was studied computationally. A twelve-hole KAUST proprietary pre-chamber geometry was investigated using CONVERGE software. The KAUST pre-chamber has an upper conical part with the spark plug, and fuel injector, followed by a straight narrow region called the throat and nozzles connecting the chambers. The simulations were run for an entire cycle, starting at the previous cycle's exhaust valve opening (EVO). The SAGE combustion model was used with the chemistry modeled using a reduced methane oxidation mechanism based on GRI Mech 3.0, which was validated against in-house OH chemiluminescence data from the optical engine experiments. Two different piston geometries, a flat piston geometry, and a more realistic bowl piston geometry were studied to understand the influence of jet

Sanal, Sangeeth, Echeverri Marquez, Manuel, Silva, Mickael, Cenker, Emre, Im, Hong G.

Unburned Mixture Heat-transfer Surface vs Mass Fraction Burned Correlation for Application in Single- and Two-zone Models of SI Engine Cycle

2022-01-045303/29/2022

Assessment of the boundaries for knock in spark ignition engines (related with self-ignition of unburned charge) is required for development of the engine control and charge composition when designing the gas engines with variable fuel compositions. In this work the extension of the single-zone model of the SI engine cycle is proposed. It includes simulation of the fresh charge temperature and pre-flame reactions based on detailed chemical kinetic mechanism of self-ignition. The heat release is modelled based on Wiebe function; the heat transfer is modelled by the Woschni correlation. To extend the capabilities of the single-zone models the closure problem of the heat-transfer surface of fresh charge to combustion chamber walls based on mass fraction burned is addressed in frame of energy balance equation for unburned charge. For model validation the simulation results are compared with the predictions of the two-zone model, which directly tracks the flame front propagation through

Zaev, Ivan Aleksandrovich, Smirnov, Sergey

Investigation of a Second Exhaust Valve Lift to Improve Combustion in a Methane - Diesel Dual-Fuel Engine

2022-01-0466

03/29/2022

In recent years, the utilization of dual-fuel combustion has gained popularity in order to improve engine efficiency and emissions. With its high knock resistance, methane allows operation in high compression diesel engines with lower risk of knocking. With the use of diesel fuel as an ignition source, it is possible to exploit the advantages of lean combustion without facing problems to provide the high amount of ignition energy necessary to burn methane under such operating conditions. Another advantage is the variety of sources from which the primary fuel can be obtained. In addition to fossil sources, methane can also be produced from biomass or electrical energy.As the rate of substitution of diesel by methane increases, the trade-off between nitrogen oxide and soot is mitigated. However, emissions of carbon monoxide and unburned methane increase. Since carbon monoxide is toxic and methane has 25 times the global warming potential of carbon dioxide, these emission components pose

Mueller, Florian, Guenthner, Michael, Weigel, Alexander, Thees, Matthias

Advanced Turbulence Model for SI Combustion in a Heavy-Duty NG Engine

2022-01-046203/29/2022

In the recent years, the interest in heavy-duty engines fuelled with Compressed Natural Gas (CNG) is increasing due to the necessity to comply with the stringent CO2 limitation imposed by national and international regulations. Indeed, the reduced number of carbon atoms of the NG molecule allows to reduce the CO2 emissions compared to a conventional fuel. The possibility to produce synthetic methane from renewable energy sources, or bio-methane from agricultural biomass and/or animal waste, contributes to support the switch from conventional fuel to CNG. To drive the engine development and reduce the time-to-market, the employment of numerical analysis is mandatory. This requires a continuous improvement of the simulation models toward real predictive analyses able to reduce the experimental R&D efforts. In this framework, 1D numerical codes are fundamental tools for system design, energy management optimization, and so on. The present work is focused on the improvement of the

Riccardi, Marco, De Bellis, Vincenzo, Bozza, Fabio, Sforza, Lorenzo, Beatrice, Carlo, Lucchini, Tommaso, Fraioli, Valentina, Golini, Stefano, Mirzaeian, Mohsen, Langridge, Simon

Machine learning assisted analysis of heat transfer characteristics of a heavy duty natural gas engine

2022-01-057203/29/2022

Heat transfer affects engine performance, efficiency, and emissions. Hence, it was essential to investigate the heat transfer characteristics after converting a compression ignition engine to a spark ignition and natural gas. The heat transfer for each engine speed and load was calculated based on Woschni’s correlation. As the number of experiments that provided engine response was limited, an artificial neural network approach was proposed to predict the engine heat transfer characteristics and aid in the analysis. The good agreement between the experimental results and data predicted by the machine learning algorithm validated the predictive capability of the artificial neural network model. The results of the data-driven analyses suggested that the heat transfer increased as the spark timing advanced. Moreover, increasing the engine speed reduced the heat flux form the combustion chamber to the engine coolant. Further, leaning the mixture lowered the heat transfer rate to the

Liu, Jinlong, Dumitrescu, Cosmin, Ulishney, Christopher

Spark Discharge Characteristics for varying Spark Plug Geometries and Gas Compositions

2022-01-052703/29/2022

Spark discharge properties were studied and characterized for varying gas compositions and spark plug geometries using a spark calorimeter and constant volume optical vessel. Two different 18mm natural gas engine spark plugs were used in the experiments. All measurements were recorded under quiescent conditions and with a spark gap of 0.30mm. The spark plug calorimeter was used for measuring thermal energy deposition to the gas for gas compositions of nitrogen, a stoichiometric mixture of nitrogen and methane, a stoichiometric mixture of nitrogen and methane, diluted with 30% carbon dioxide by volume, and for air. Other measurements of interest included breakdown voltage, electrical energy delivered to the spark gap, electrical-to-thermal energy conversion efficiency, and spark duration, for pressures up to 28 bar at 300K. The optical vessel was used for the combusting mixture of stoichiometric air and methane at pressures up to 28 bar. For these experiments, thermal energy deposition

Tambasco, Corey, Hall, Matthew, Matthews, Ron

Parametric study in a stoichiometric diesel micro-pilot natural gas engine for efficiency optimization

2022-01-055803/29/2022

Diesel piloted natural gas engine's performance varies depending on operating conditions and has shown to perform best under medium to high load. It can often be equal to or better the fuel efficiency of a diesel-only engine in this operating range. In this paper, a multi-cylinder multi-cylinder diesel 6.7L engine was converted to run stoichiometric natural gas /diesel micro-pilot combustion with a maximum diesel contribution of 10%. The effects of combustion controling parameters, including the pilot start of injection, pilot injection pressure, pilot injection quantity, EGR, and global equivalence ratio were experimentally studied using the Taguchi Orthogonal Matrix approach while operating at stoichiometric conditions. Furthermore, a 1-D simulation model was calibrated with the experimental data to assess further efficiency improvement by optimizing the turbocharger and combustion chamber geometry. It was observed that EQR and the diesel pilot SOI are primary factors impacting

Bonfochi Vinhaes, Vinicius, Yang, Xuebin, Eggart, Brian, McTaggart-Cowan, Gordon, Munshi, Sandeep, Naber, Jeffrey, Shahbakhti, Mahdi

Detection and Onset Determination of End-Gas Autoignition on Spark-Ignited Natural Gas Engines Based on the Apparent Heat Release Rate

2022-01-056303/29/2022

Natural Gas used in high-efficiency engines holds promise as a low-cost intermediate solution to reduce Greenhouse Gases and particulate matter. However, to achieve high engine efficiencies, engines need to be operated at higher power levels and increased Brake Mean Effective Pressures (BMEP), which is limited by destructive, engine damaging knock. Alternatively, if controlled, the same End-Gas Autoignition (EGAI) process responsible for knock can boost efficiencies and consume unburned methane while leveraging low-cost traditional exhaust aftertreatment technologies, such as a three-way catalyst, to minimize environmental impact. For this reason, this work has developed a method to detect the presence of EGAI and to determine its onset location (or crank angle). This method is based on the characteristic shape of the Apparent Heat Release Rate (AHRR) curve under four levels of EGAI, where, by searching for the presence and location of inflection points one can determine the onset

Bernardi Bestel, Diego, Rodriguez, Juan, Marchese, Anthony, Olsen, Daniel, Windom, Bret

Numerical and Experimental Analysis of Abnormal Combustion in a SI Gasoline Engine with a Re-Entrant Piston Bowl and Swirl Flow

2022-32-003801/09/2022

Some SI (spark-ignition) engines fueled with gasoline for industrial machineries are designed based on the conventional diesel engine in consideration of the compatibility with installation. Such diesel engine-based SI engines secure a combustion chamber by a piston bowl instead of a pent-roof combustion chamber widely applied for SI engines for automobiles. In the development of SI engines, because knocking deteriorates the power output and the thermal efficiency, it is essential to clarify causes of knocking and predict knocking events. However, there has been little research on knocking in diesel engine-based SI engines. The purpose of this study is to elucidate knocking phenomena in a gasoline engine with a re-entrant piston bowl and swirl flow numerically and experimentally. In-cylinder visualization and pressure analysis of knock onset cycles have been experimentally performed. Locations of autoignition have been predicted by 3D-CFD analysis with detailed chemical reactions. The

Matsuoka, Ayano, Shiraishi, Kentaro, Kishi, Shinji, Bae, Jaeok, Kaneko, Makoto, Kuboyama, Tatsuya, Moriyoshi, Yasuo

Extension of the Lean Limit of Gasoline Engines Under Part Load by Using Hot Surface Assisted Spark Ignition (HSASI)

2022-32-005101/09/2022

Charge dilution by lean-burn is one way to increase the efficiency of spark ignition engines while reducing NOx emissions. This work focuses on increasing the flammability of lean mixtures inside a passive pre-chamber spark plug by elevating its temperature with the help of a controllable hot surface integrated into the pre-chamber. Thus, an extension of the lean limit under part load is aimed for. A pre-chamber spark plug prototype with an integrated, controllable glow plug was developed, called Hot Surface Assisted Spark Ignition (HSASI). Experimental investigations were conducted on a single-cylinder engine at the Karlsruhe University of Applied Sciences. Operating modes with an active glow plug (HSASI) and a non-active glow plug were compared. The lean limit for both operation modes were determined under part load. NOx, CO and THC emissions were measured for different air-fuel equivalence ratios λ. The lean limit is extended by more than 0.1 in λ at low loads with HSASI operation

Holzberger, Sascha, Kettner, Maurice, Kirchberger, Roland

Combustion Performance of Methane Fermentation Gas with Hydrogen Addition under Various Ignition Timings

2022-32-004301/09/2022

Hydrogen (H2) addition is widely used for natural gas combustion to improve the engine efficiency. However, less attention was paid on the various ignition timings for the maximum brake torque (MBT) and brake thermal efficiency (BTE). In order to check the ignition timing effect, experiments were performed in a spark ignition engine with engine speed fixed on 1500 revolutions per minute (rpm). Firstly, CH4 was only used for combustion with excess air ratio (λ) changing from 0.8 to 1.4. Then, co-combustion of 50 vol% CH4 and 50 vol% CO2 was checked to simulate methane fermentation gas. Finally, H2 was added with volume percentage varying from 5% to 20%. Among these discussions, torque, brake mean effective pressure (BMEP), BTE and cylinder pressure were evaluated. Based on the results, high efficiency can be achieved by advancing the ignition timing with H2 addition at λ=1.4. However, with H2 addition, the ignition timing should be retarded to obtain higher BTE. At the lean-burn

Luo, Hongliang, Jin, Yu, An, Yanzhao, Matsumura, Yukihiko, Ichikawa, Takayuki, Kim, Wookyung, Nakashimada, Yutaka, Nishida, Keiya

Effect of Different Fuel Supply System on Combustion Characteristics in Hydrogen SI Engine

2022-32-009201/09/2022

In recent years, internal combustion engine using hydrogen gas, has attracted attention as one solution to the problem of global warming. Hydrogen gas has excellent combustion characteristics such as wide limits of inflammability and fast burning velocity because of high diffusion rate. Therefore, it has been made to obtain stable ignition and combustion by adding hydrogen with lean mixture in spark ignition engines using hydrocarbon fuels and to be attempted efficient operation by engine researchers. The purpose of this study is to reduce cooling loss in a gas engine using hydrogen gas and hydrogen Mixer system (Mixer) engine was remodeled to hydrogen Port Injection (PI) system engine. In this report, the heterogeneity of hydrogen mixture is clarified by comparing the combustion characteristics of the Mixer and the PI, and the effect of the difference in hydrogen supply systems on cooling loss is system. Ignition delay of the PI system is shorter than that of the Mixer. This is to

Koshikawa, Shoi, Matsuya, Yuki, Sekine, Tsukasa, Matsumura, Eriko, Senda, Jiro, Morita, Gin, Nakazono, Toru

Improvements of Combustion and Emissions in a Natural Gas Fueled Engine with Hydrogen Enrichment and Optimized Injection Timings of the Diesel Fuel

2022-32-009501/09/2022

In a natural gas fueled engine ignited by diesel fuel, the addition of hydrogen to the engine could be a possible way to improve thermal efficiency and reduce unburned methane which has a warming potential many times that of carbon dioxide as it promotes a more rapid and complete combustion. This study carried out engine experiments using a single cylinder engine with natural gas and hydrogen delivered separately into the intake pipe, and with pilot-injection of diesel fuel. The percentages of hydrogen in the natural gas-hydrogen mixtures were varied from 0% to 50% of the heat value. The results showed that the hydrogen addition has an insignificant effect on the ignition delay of the diesel fuel and that it shortens the combustion duration. The increase in the hydrogen ratio decreased the unburned hydrocarbon emissions more than the reduction of the amount of natural gas that was replaced by the hydrogen. Further, the direct injection timing of the diesel fuel was varied from early in

Kobashi, Yoshimitsu, Inagaki, Ryuya, Shibata, Gen, Ogawa, Hideyuki

Analysis of a gas engine with arbitrary mixture ratio of hydrogen and methane for heavy-duty vehicles

2021-01-117709/21/2021

To reduce exhaust emissions in commercial vehicles, hydrogen, as a carbon-free fuel, is a reasonable alternative to conventional fuels. In order to circumvent the current problem of hydrogen availability, the use of a gas engine for heavy duty vehicles(hdv), which is able to operate with pure compressed natural gas (CNG), pure hydrogen as well as any mixture of these both gases, is sensible. For this purpose, an operating concept for a gas engine was developed, which is able to operate with an arbitrary hydrogen-natural gas mixture ratio. For this purpose, the mixture formation of a hydrogen-natural gas-air mixture was analysed in a 3D CFD simulation. The results for pure hydrogen operation show a very good homogenization of the fuel distribution at the point of ignition when an outward-opening injector was used. Based on these results, a 1D simulation was used to generate an operating map of the gas engine and investigate it with regard to its efficiency and exhaust emissions. A lean

Klepatz, Kevin, Tempelhagen, Robin, Rottengruber, Hermann

Spark Ignition Discharge Characteristics under Quiescent Conditions and with Convective Flows

2021-01-115709/21/2021

The arc characteristics and discharge behavior of a representative inductive spark ignition system were characterized with a spark plug calorimeter and a constant volume vessel used to create high-pressure crossflow velocities through the gap of the spark plug. A 14 mm diameter natural gas engine spark plug was used for the measurements. The discharges were into a non-combusting gas, primarily nitrogen. The spark plug calorimeter was used to determine the electrical-to-thermal energy conversion in the spark gap under quiescent conditions, while the constant volume vessel was used to study ignition arc structure in convective crossflows and imaged with a high-speed camera. Topics included the effect of crossflow velocity, pressure (up to 20 bar at 300 K), and gap distance on breakdown voltage, arc duration and delivered electrical energy. Also of interest was the amount of remaining electrical energy on the coil versus spark duration in a cross flow. Resistance of the arc plasma during

Tambasco, Corey, Li, Delong, Hall, Matthew, Matthews, Ronald

Assessment of the Knock Prediction Capabilities with Single-Zone Thermodynamic Model of SI Engine and Detailed Chemical Kinetic Mechanisms of Fuel Combustion

2021-01-114509/21/2021

Assessment of the boundaries for self-ignition of unburned charge in spark ignition engines (also related to knock) is required for development of the engine concepts and controls with respect to charge composition, spark advance and valve timing when designing the gas engines with wide range of the fuel compositions and converting compression ignition engines to gas engines. In this paper the combination of the single-zone model of the SI engine and chemical kinetics modeling is evaluated as a rapid prototyping tool for prediction of the self-ignition of the unburned charge in SI engine. The single-zone model simulates the cylinder pressure history based on Wiebe heat release function. The simulation of the self-ignition of the unburned charge is performed with coupled solution of the system of ordinary differential equations for temperature and species concentration with detailed chemical kinetic mechanism. Three fuels were considered: primary reference fuel, methane, hydrogen. The

Zaev, Ivan, Smirnov, Sergei

Conversion Performance Prediction of Thermal-Deteriorated Three-Way Catalysts: Surface Reaction Model Development Considering Platinum Group Metals and Co-Catalyst

2021-24-007709/05/2021

Three-way catalyst (TWC) converters can purify harmful substances, such as carbon monoxide, nitrogen oxides, and hydrocarbons, from the exhaust gases of gasoline engines. However, large amounts of these substances may be emitted before the TWC reaches its light-off temperature during cold starts, and its performance may be impaired by thermal deterioration during high-load driving. In this work, a simulation model was developed using axisuite commercial software by Exothermia S.A to predict the light-off conversion performance of Pd/CeO2-ZrO2-Al2O3 catalysts with different degrees of thermal deterioration. The model considered detailed surface reactions and the main factor of the deterioration mechanism. In the detailed reaction mechanism, adsorption, desorption, and surface reactions of each gas species at active sites of the platinum group metal (PGM) particles were considered based on the Langmuir-Hinshelwood mechanism. Model gas experiments were performed to identify each reaction

Yamakawa, Yukihiro, Inoue, Ryoya, Kubo, Yunosuke, Yamaguchi, Kyohei, Kusaka, Jin

Modeling of Three Way Catalyst Behavior Under Steady and Transient Operations in a Stoichiometric Natural Gas Fueled Engine

2021-24-007409/05/2021

Methane abatement in the exhaust gas of natural gas engines is much more challenging in respect to the oxidation of other higher order hydrocarbons. Under steady state λ sweep, the methane conversion efficiency is high at exact stoichiometric, and decreases steeply under both slightly rich and slightly lean conditions. Transient lean to rich transitions can improve methane conversion at the rich side. Previous experimental work has attributed the enhanced methane conversion to activation of methane steam reforming. The steam reforming rate, however, attenuates over time and the methane conversion rate gradually converges to the low steady state values. In this work, a reactor model is established to predict steady state and transient transition characteristics of a three-way catalyst (TWC) mounted in the exhaust of a natural gas heavy-duty engine. In total 17 global reactions are selected and implemented in the reactor model, including oxidation reactions, NOx related reactions, water

Wang, Moyu, Dimopoulos Eggenschwiler, Panayotis

Knock: A Century of Research

03-15-01-0004

07/28/2021

Knock is one of the main limitations on increasing spark-ignition (SI) engine efficiency. This has been known for at least 100 years, and it is still the case today. Knock occurs when conditions ahead of the flame front in an SI engine result in one or more autoignition events in the end gas. The autoignition reaction rate is typically much higher than that of the flame-front propagation. This may lead to the creation of pressure waves in the combustion chamber and, hence, an undesirable noise that gives knock its name. The resulting increased mechanical and thermal loading on engine components may eventually lead to engine failure. Reducing the compression ratio lowers end-gas temperatures and pressures, reducing end-gas reactivity and, hence, mitigating knock. However, this has a detrimental effect on engine efficiency. Automotive companies must significantly reduce their fleet carbon dioxide (CO2) values in the coming years to meet targets resulting from the 2015 Paris Agreement

Corrigan, Daire James, Fontanesi, Stefano

Knock: A Century of Research

03-15-01-0004-TEST-REC07/28/2021

Corrigan, Daire James, Fontanesi, Stefano

Experimental and 0D Numerical Investigation of Ultra-Lean Combustion Concept to Improve the Efficiency of SI Engine

2021-01-038404/06/2021

Recently, the car manufacturers are moving towards innovative Spark Ignition (SI) engine architectures with unconventional combustion concepts, aiming to comply with the stringent regulation imposed by EU and other legislators. The introduction of burdensome cycles for vehicle homologation, indeed, requires an engine characterized by a high efficiency in the most of its operating conditions, for which a conventional SI engine results to be ineffective. Combustion systems which work with very lean air/fuel mixture have demonstrated to be a promising solution to this concern. Higher specific heat ratio, minor heat losses and increased knock resistance indeed allow improving fuel consumption. Additionally, the lower combustion temperatures enable to reduce NOX production. Since conventional SI engines can work with a limited amount of excess air, alternative solutions are being developed to overcome this constraint and reach the above benefit. Among all these solutions, replacing the

De Bellis, Vincenzo, Malfi, Enrica, Bozza, Fabio, KUMAR, Deepak, Serrano, David, Dulbecco, Alessio, Zaccardi, Jean-Marc

TOC

99-03-01-0TOC02/12/2021

TOC

Tobolski, Sue

Model-Based Precise Air-Fuel Ratio Control for Gaseous Fueled Engines

02-13-03-0017

10/09/2020

In this article, an adaptive state estimation algorithm for precise air-fuel ratio (AFR) control is presented. AFR control is a critical part of internal combustion engine (ICE) control, and tight AFR control delivers lower engine emissions, better engine fuel economy, and better engine transient performance. The proposed control algorithm significantly improves transient AFR control to eliminate and reduce the amplitude of the lean and rich spikes during transients. The new algorithm is first demonstrated in simulation (using Matlab/SimulinkTM and GT-PowerTM) and then verified on a test engine. The engine tests are conducted using the European Transient Cycle (ETC) with HoribaTM double-ended dynamometer. The developed algorithm utilizes a nonlinear physics-based engine model in the observer and advanced control principles with modifications to solve real industrial control issues. This method dramatically reduces on-engine AFR transient calibration efforts, which was one of the

Han, Yi, Young, Peter

Fuels in Ground Support Equipment (Other Than Gasoline or Diesel)

AIR5373A (Current)

09/23/2020

This SAE Aerospace Information Report (AIR) is intended as a source of comparative information and is subject to change to keep pace with experience and technical advances. This document describes currently used fuels and fuels which may be used in the future. Conventional gasoline and diesel fuels are intentionally omitted from this document.

AGE-3 Aircraft Ground Support Equipment Committee