Browse Topic: Ignition timing

Items (986)

COMBUSTION STRATEGIES FOR LOW-CETANE FUELS

2024-01-3788

11/15/2024

ABSTRACT The effects of advanced fuel injection strategies on the combustion behavior of an unblended low-cetane synthetic jet fuel (Sasol isoparaffinic kerosene, POSF 7629, derived cetane number 31) were investigated in a single-cylinder research engine (SCRE) at several speeds and loads. The most significant finding of the current work is that the introduction of a small pulse of fuel prior to the main fuel injection event, termed a close-coupled pilot (CCP) injection, effectively mitigates the relatively longer ignition delay time of the DCN 31 fuel. Therefore, a potential technical solution exists that would permit the use of low-cetane jet fuels in military ground vehicles if the operational scenario required it. Citation: M. Tess, E. Gingrich, S. Stoll, “Combustion Strategies for Low-Cetane Fuels”, In Proceedings of the Ground Vehicle Systems Engineering and Technology Symposium (GVSETS), NDIA, Novi, MI, Aug. 13-15, 2019

Tess, Michael, Gingrich, Eric, Stoll, Steve

Performance and Emissions of a Hydrogen Dual-Fuel Engine Using Diesel and HVO as Pilot Fuels

2024-01-4286

11/05/2024

A comprehensive experimental study of hydrogen–diesel dual-fuel and hydrogen-hydrotreated vegetable oil (HVO) dual-fuel operations was conducted in a single-cylinder diesel engine (bore 85.0 mm, stroke 96.9 mm, and compression ratio 14.3) equipped with a common rail fuel injection system and a supercharger. The hydrogen flow rate was manipulated by varying the hydrogen excess air ratio from 2.5 to 4.0 in 0.5 increments. Hydrogen was introduced into the intake pipe using a gas injector. Diesel fuel and HVO were injected as pilot fuels at a fixed injection pressure of 80 MPa. The quantity of pilot fuel was set to 3, 6, and 13 mm3/cycle. The intake and exhaust pressures were set in the range of 100–220 kPa in 20 kPa increments. The engine was operated at a constant speed of 1,800 rpm under all conditions. The pilot injection timing was varied such that the ignition timing was constant at the TDC under all conditions. The results demonstrated that smoke was lower when HVO was used as the

Mukhtar, Ghazian Amin, Tange, Kota, Nakatani, Satoshi, Horibe, Naoto, Kawanabe, Hiroshi, Morita, Gin, Hiraoka, Kenji, Koda, Kazuyuki

Physics Based On-Board Exhaust-Temperature Prediction Model for Highly Efficient and Low-Emission Powertrain

2024-01-4273

11/05/2024

Modern automotive powertrains are operated using many control devices under a wide range of environmental conditions. The exhaust temperature must be controlled within a specific range to ensure low exhaust-gas emissions and engine-component protection. In this regard, physics-based exhaust-temperature prediction models are advantageous compared with the conventional exhaust-temperature map-based model developed using engine dyno testing results. This is because physics-based models can predict exhaust-temperature behavior in conditions not measured for calibration. However, increasing the computational load to illustrate all physical phenomena in the engine air path, including combustion in the cylinder, may not fully leverage the advantages of physical models for the performance of electric control units (ECUs). This study proposes an onboard physics-based exhaust-temperature prediction model for a mass-produced engine to protect the engine exhaust system and reduce exhaust emissions

Yamaguchi, Seiya, Tomita, Masayuki, Urakawa, Shinji, Ookubo, Seiichi

Fuel Design Concept to Improve Both Combustion Stability and Antiknocking Property Focusing on Ethane

2024-01-4276

11/05/2024

For realizing a super-leanburn SI engine with a very-high compression ratio, it is necessary to design a new fuel which could have low ignitability at a low temperature for antiknocking, but high ignitability at a high temperature for some contribution to stable combustion. C2H6 has a very-long ignition delay time at a low temperature, close to that of CH4, but a short ignition delay time at a high temperature, close to that of gasoline. C2H6 also has a laminar burning velocity about 1.2 times higher than that of gasoline. C2H6 addition to gasoline could be a good example of fuel design to improve both combustion stability and antiknocking property. In the present study, the antiknocking effect of adding CH4, C2H6, or C3H8 with the RON of 120, 115, or 112, respectively, to a regular-gasoline surrogate fuel with the RON of 90.8 has been investigated in an SI engine with a stoichiometric mixture. With the energy fraction of the gaseous fuel of less than 0.35, knocking limit CA50 is

Kuwahara, Kazunari, Shimizu, Taisei, Okada, Atsuki

Methanol Combustion in Compression Ignition Engines with a Combustion Enhancer Based on Nitrates (CEN): Insights from an Experimental Study in a New One-Shot Engine (NOSE

2024-01-4281

11/05/2024

Because it can be produced in a green form methanol is envisioned as a potential fuel replacing conventional Diesel fuel to directly reduce greenhouse gases (GHG) impact of maritime transportation. For these reasons, Original Equipment Manufacturers (OEMs) are working to make methanol easier to use in Compression Ignition (CI) engines. While it is an easy to use substance with manageable energy content, methanol has a few drawbacks, such as: high latent heat of vaporization, high auto-ignition temperature. These drawbacks have an impact on the quality of combustion and therefore solutions have to be found and are still being studied to give methanol a Diesel like behavior. One solution is to use a pilot fuel for ignition in quantities that remain high (> 20 %). A previous study carried out at the PRISME laboratory highlighted the possibility of using a Combustion Enhancer based on Nitrates (CEN) at additive levels. Here the CEN impact in methanol is studied through the use of a New One

Samson, Richard, Morin, Anne-Gaelle, Foucher, Fabrice

Spray Ignition of Primary Reference Fuels Blended with Ethanol and 2,5-Dimethylfuran

2024-01-4294

11/05/2024

Engine knocking poses a significant challenge for downsizing and boosting strategies in spark-ignition (SI) engines. In the event of knock, the unburnt fuel-oxidizer mixture auto-ignites after being compressed by the flame front and piston of an SI engine. Conventional knock is influenced by combustion chemistry and physical properties of the fuel. In this work, we present auto-ignition characteristics of primary reference fuel (PRF75), ethanol, 2,5-dimethylfuran, and their blends in Advanced Fuel Ignition Delay Analyzer (AFIDA). Three different pressures, i.e. 10, 15, and 20 atm and four different temperatures, i.e. 450, 500, 550, and 600 0C have been used as initial conditions. A weak negative temperature coefficient (NTC) behavior has been observed for PRF75 ignition in AFIDA in this work. Moreover, for PRF75, the ignition delay times at low temperatures have been observed to show weaker dependence on pressure in comparison to the high temperature cases. For ethanol and 2,5

Bhattacharya, Atmadeep, Kaario, Ossi, Eraqi, Basem, Sakleshpur Nagaraja, Shashank, Sarathy, Mani

Heater and Accessories, Aircraft Internal Combustion Heat Exchanger Type

AS8040C (Current)

10/03/2024

This SAE Aerospace Standard (AS) covers combustion heaters and accessories used in, but not limited to, the following applications: a Cabin heating (all occupied regions and windshield heating) b Wing and empennage anti-icing c Engine and accessory heating (when heater is installed as part of the aircraft) d Aircraft deicing

AC-9 Aircraft Environmental Systems Committee

Novel Chemical Kinetics Mechanism for Robust Simulation of Multi-Component Fuel Blends in Engine Conditions

2024-24-0035

09/18/2024

Ammonia, with its significant hydrogen content, offers a practical alternative to pure hydrogen in marine applications and is easier to store due to its higher volumetric energy density. While Ammonia's resistance to auto-ignition makes it suitable for high-compression ratio engines using pre-mixed charge, its low flame speed poses challenges. Innovative combustion strategies, such as dual-fuel and reactivity-controlled compression ignition (RCCI), leverage secondary high-reactivity fuels like diesel to enhance Ammonia combustion. To address the challenges posed by Ammonia's low flame speed, blending with hydrogen or natural gas (NG) in the low reactivity portion of the fuel mixture is an effective approach. For combustion simulation in engines, it is crucial to develop a chemical kinetics mechanism that accommodates all participating fuels: diesel, Ammonia, hydrogen, and NG. This study aims to propose a kinetics mechanism applicable for the combustion of these fuels together. The

Salahi, Mohammad Mahdi, Mahmoudzadeh Andwari, Amin, Kakoee, Alireza, Hyvonen, Jari, Gharehghani, Ayat, Mikulski, Maciej, Lendormy, Éric

Numerical and Experimental Analysis of Dual Fuel Hydrogen/Diesel Combustion at Varying Engine Speed on a Single Cylinder Engine

2024-24-0044

09/18/2024

In this study, dual fuel combustion process has been investigated numerically and experimentally in a single cylinder research engine. Two engine speeds have been investigated (1500 and 2000 rpm) at fixed BMEP of 5 bar for both engine speeds. For each engine speed two operating points have tested with and without EGR (Exhaust Gas Recirculation). The hydrogen has been injected in the intake manifold in front of the tumble intake port inlet and a small amount of diesel fuel has been introduced directly in the cylinder through two injections strategy: one pilot injection occurring Before Top Dead Center (BTDC) and one main occurring around the Top Dead Center (TDC). The dual-fuel combustion model in GT-SUITE has been used first to calibrate the combustion model by using the Three Pressure Analysis (TPA) model. This step allows the calibration of the combustion model to predict in-cylinder combustion processes. Simulations have been performed at varying mass distribution of injected diesel

Maroteaux, Fadila, SEBAI, Salim, Mancaruso, Ezio, Rossetti, Salvatore, Schembri, Patrick, Radja, Katia, Barichella, Arnault

Effect of Ethanol and Iso-Octane Blends on Isolated Low-Temperature Heat Release in a Spark Ignition Engine

04-17-03-0016

05/17/2024

Low-temperature heat release (LTHR) is of interest for its potential to help control autoignition in advanced compression ignition (ACI) engines and mitigate knock in spark ignition (SI) engines. Previous studies have identified and investigated LTHR in both ACI and SI engines before the main high-temperature heat release (HTHR) event and, more recently, LTHR in isolation has been demonstrated in SI engines by appropriately curating the in-cylinder thermal state during compression and disabling the spark discharge. Ethanol is an increasingly common component of market fuel blends, owing to its renewable sources. In this work, the effect of adding ethanol to iso-octane (2,2,4-trimethylpentane) blends on their LTHR behavior is demonstrated. Tests were run on a motored single-cylinder engine elevated inlet air temperatures and pressures were adjusted to realize LTHR from blends of iso-octane and ethanol without entering the HTHR regime. The blends were tested with inlet temperatures of 40

White, Samuel Philip, Bajwa, Abdullah Umair, Leach, Felix

Effect of Spark Assisted Compression Ignition on the End-Gas Autoignition with DME-air Mixtures in a Rapid Compression Machine

2024-01-2822

04/09/2024

Substantial effort has been devoted to utilizing homogeneous charge compression ignition (HCCI) to improve thermal efficiency and reduce emission pollutants in internal combustion engines. However, the uncertainty of ignition timing and limited operational range restrict further adoption for the industry. Using the spark-assisted compression ignition (SACI) technique has the advantage of using a spark event to control the combustion process. This study employs a rapid compression machine to characterize the ignition and combustion process of Dimethyl ether (DME) under engine-like background temperature and pressures and combustion regimes, including HCCI, SACI, and knocking onsite. The spark ignition timing was swept to ignite the mixture under various thermodynamic conditions. This investigation demonstrates the presence of four distinct combustion regimes, including detonation, strong end-gas autoignition, mild end-gas autoignition, and HCCI. The observation indicates that HCCI

Jin, Long, Yu, Xiao, Wang, Meiping, Reader, Graham, Zheng, Ming

Optical Diagnostic Study on Ammonia-Diesel and Ammonia-PODE Dual Fuel Engines

2024-01-2362

04/09/2024

Ammonia shows promise as an alternative fuel for internal combustion engines (ICEs) in reducing CO2 emissions due to its carbon-free nature and well-established infrastructure. However, certain drawbacks, such as the high ignition energy, the narrow flammability range, and the extremely low laminar flame speed, limit its widespread application. The dual fuel (DF) mode is an appealing approach to enhance ammonia combustion. The combustion characteristics of ammonia-diesel dual fuel mode and ammonia-PODE3 dual fuel mode were experimentally studied using a full-view optical engine and the high-speed photography method. The ammonia energy ratio (ERa) was varied from 40% to 60%, and the main injection energy ratio (ERInj1) and the main injection time (SOI1) were also varied in ammonia-PODE3 mode. The findings demonstrate that ammonia-PODE3 mode exhibits better ignition characteristics than ammonia-diesel mode, resulting in an earlier ignition start, a larger flame area, a larger flame

Mao, Jianshu, Zhang, Yixiao, Ma, Yue, Ma, Xiao, Wang, Zhi, Wang, Zhenqian, Shuai, Shijin

Estimating Light-Duty Vehicle Gaseous Emissions Using a Data-Driven Approach in Off-Cycle Measurements

2024-01-2705

04/09/2024

As global regulations on automotive tailpipe emissions become increasingly stringent, developing precise tailpipe emissions models has garnered significant attention to fulfill onboard monitoring requirements without some drawbacks associated with traditional sensor-based systems. Within the European Union, there is consideration of mandating real-time measurement of emission constituents to enable driver warnings in cases where constituent standards are exceeded. Presently, available technology renders this approach cost-prohibitive and technologically challenging, with most sensor suppliers either unable to meet the demand or unwilling to justify the development costs associated with sensor commercialization. Efforts to circumvent the sensor-based approach through first principle models, incorporating thermokinetics, have proven to be both computationally expensive and lacking in accuracy during transient operations. We propose a data-driven solution based on DL (deep learning) to

Hashemi, Ashton, Schlingmann, Dean

Effect of Port Water Injection on the Knock and Combustion Characteristics for an Argon Power Cycle Hydrogen Engine

2024-01-2612

04/09/2024

Argon power cycle hydrogen engine is an internal combustion engine that employs argon instead of nitrogen of air as the working fluid, oxygen as the oxidizer, and hydrogen as the fuel. Since argon has a higher specific heat ratio than air, argon power cycle hydrogen engines have theoretically higher indicated thermal efficiencies according to the Otto cycle efficiency formula. However, argon makes the end mixture more susceptible to spontaneous combustion and thus is accompanied by a stronger knock at a lower compression ratio, thus limiting the improvement of thermal efficiency in engine operation. In order to suppress the limitation of knock on the thermal efficiency, this paper adopts a combination of experimental and simulation methods to investigate the effects of port water injection on the knock suppression and combustion characteristics of an argon power cycle hydrogen engine. The results show that the port water injection can effectively reduce the knock intensity of the argon

Tang, Yongjian, Deng, Jun, Xie, Kaien, Jin, Shaoye, Li, Liguang

Numerical Simulation of Ammonia-Hydrogen Engine Using Low-Pressure Direct Injection (LP-DI

2024-01-2118

04/09/2024

Ammonia (NH3), a zero-carbon fuel, has great potential for internal combustion engine development. However, its high ignition energy, low laminar burning velocity, narrow range of flammability limits, and high latent heat of vaporization are not conducive for engine application. This paper numerically investigates the feasibility of utilizing ammonia in a heavy-duty diesel engine, specifically through low-pressure direct injection (LP-DI) of hydrogen to ignite ammonia combustion. Due to the lack of a well-corresponding mechanism for the operating conditions of ammonia-hydrogen engines, this study serves only as a trend-oriented prediction. The paper compares the engine's combustion and emission performance by optimizing four critical parameters: excess air ratio, hydrogen energy ratio, ignition timing, and hydrogen injection timing. The results reveal that excessively high hydrogen energy ratios lead to an advanced combustion phase, reducing indicated thermal efficiency. Additionally

Xu, Xiaoting, Wang, Wei, Qi, Yunliang, Wang, Zhi, Min, Haijiao, Li, Fangwei, Yin, Yong, Li, Zhi

Comparison of the Predictive Capabilities of Chemical Kinetic Models for Hydrogen Combustion Applications

2024-01-2116

04/09/2024

Recent legislation banning the sale of new petrol and diesel vehicles in Europe from 2035 has shifted the focus of internal combustion engine research towards alternative fuels with net zero tailpipe emissions such as hydrogen. Research regarding hydrogen as a fuel is particularly pertinent to the so-called ‘hard-to-electrify’ propulsion applications, requiring a combination of large range, fast refuelling times or high-load duty cycles. The virtual design, development, and optimisation of hydrogen internal combustion engines has resulted in the necessity for accurate predictive modelling of the hydrogen combustion and autoignition processes. Typically, the models for these processes rely respectively on laminar flame speed datasets to calculate the rate of fuel burn as well as ignition delay time datasets to estimate autoignition timing. These datasets are generated using chemical kinetic mechanisms available in the literature. However, these mechanisms have typically been developed

Ribnishki, Aleksandar, Charles, Cameron, Esposito, Stefania, Akehurst, Sam, Yuan, Hao

Evaluation of closed-loop combustion phase optimization for varying fuel compensation and cylinder balancing in a HD SI-ICE

2024-01-2837

04/09/2024

Alternative fuels, such as natural and bio-gas, are attractive options for reducing greenhouse gas emissions from combustion engines. However, the naturally occurring variation in gas composition poses a challenge and may significantly impact engine performance. The gas composition affects fundamental fuel properties such as flame propagation speed and heat release rate. Deviations from the gas composition for which the engine was calibrated result in changes in the combustion phase, reducing engine efficiency and increasing fuel consumption and emissions. However, the efficiency loss can be limited by estimating the combustion phase and adapting the spark timing, which could be implemented favorably using a closed-loop control approach. In this paper, we evaluate the efficiency loss resulting from varying gas compositions and the benefits of using a closed-loop controller to adapt the spark timing to retain the nominal combustion phase. We use a 13-liter natural gas-fueled heavy-duty

Björnsson, Ola, Tunestal, Per

A Study on the Relationship between ECN Spray D and Marine-Sized Nozzles Using FGM Combustion Model

2024-01-2695

04/09/2024

Present work investigates the relationship between the combustion parameters of a well-known ECN heavy-duty nozzle called Spray D and marine-size nozzles. The study is carried out in OpenFOAM software within the framework of RANS turbulence modelling, using a flamelet based tabulation technique known as FGM to model the combustion. The large nozzles are tested in a constant volume chamber representative of marine engines, for which a CFD setup is validated against inert data in literature. The reacting results have been validated first with experimental data, initializing the domain with a highly reactive environment (23% oxygen) and engine-like swirl. Then, a less reactive initial condition was set up in the domain (15% oxygen) without swirl, to achieve a Spray D-like environment. The main goal is to study the variation of the combustion parameters Ignition Delay Time (IDT) and Lift-Off Length (LOL) as function of nozzle diameter, leading to a mathematical correlation to estimate the

Di Matteo, Andrea, Somers, Bart

Development of a Direct-Injection Heavy-Duty Hydrogen Engine

2024-01-2609

04/09/2024

Hydrogen-fuelled internal combustion engines (ICEs) offer a zero-carbon fuel option for many applications. As part of the global effort to study hydrogen ICEs Ricardo has developed single-cylinder and multi-cylinder heavy-duty engines. The engines are representative of a 13 litre Euro VI heavy-duty production application converted to run on hydrogen fuel with limited changes. The engine is fitted with direct hydrogen injectors which enable flexible injection strategies and reduce hydrogen in the intake system. Steady-state testing was carried out over an array of speed and load points covering a typical heavy-duty drive-cycle area. Engine test results are presented and analysed in this paper. The combustion system can run to values exceeding lambda 5 and 40% exhaust gas recirculation (EGR) can be tolerated. The impact of lambda, EGR, injection and ignition timing variations are presented and demonstrate how the system responds to the corresponding changes in specific heat capacity

Osborne, Richard, Hughes, John, Loiudice, Angela, Penning, Richard, Valenta, Lukáš

Effect of Timing Strategy on Mixture Formation, Performance and Emission of Inlet Injection Hydrogen Engine

2024-01-2614

04/09/2024

In order to scrutinize the timing variables impacting the combustion performance and emissions of the Port Fuel Injection hydrogen engine (PFI-H2ICE), a model of a four-cylinder hydrogen engine is meticulously built utilizing the 1D software GT-POWER. The effect of excess air coefficients and timing strategies (including the intake valve opening timing (IVO), the start of injection timing (SOI), and ignition timing) is analyzed in this study. The main conclusions are as follows: The hydrogen engine remold from the Isuzu JE4N28 nature gas engine manifests a lean combustion threshold ranging between 2.0 and 2.5. Notably, advancing intake valve opening timing by 20°CA has proven beneficial to the brake thermal efficiency (BTE) of the hydrogen engine while reducing the NOx emissions by a substantial margin, and advancing intake valve opening timing bears the virtue of strengthen the positive influence of the start of injection timing upon the engine's combustion performance. The longer the

Hu, Zhiyuan, Yin, Li, Zhang, Yunhua, Lou, Diming, Tan, Piqiang, Liu, Dengcheng

Experimental Study of Piston Temperature Profile with Respect to Varying Engine Parameters – Using Telemetry Method

2024-26-0341

01/16/2024

As emissions standards become more stringent, OEMs are pushing engines to run on leaner fuel mixtures, which puts increased thermal stress on components, particularly pistons, causing them to operate at higher temperatures. This requires more robust design and rigorous testing of components. Telemetry methods offer accurate and real-time feedback, allowing designers to test components at various operating conditions, providing more flexibility than other traditional methods. Piston temperature measurement is a critical aspect of engine development because it directly affects engine performance and durability. Among the various techniques available for this purpose, telemetry methods have gained considerable attention in recent years. This method involves integrating temperature sensors and transmitter on the piston, which transmit temperature data wirelessly to a receiver outside the engine. In this paper, we evaluate the impact of coolant temperatures, valve timing, ignition timing

Pandey, Ram Krishan, Kumar, Atul, Jangra, Sumit

Validation of a CFD hydrogen combustion model on an PFI SI engine under lean combustion

2023-36-0125

01/08/2024

In order to further explore the potential of hydrogen as an alternative fuel, this study aims to validate a computational fluid dynamics model for hydrogen combustion in a port fuel injection spark ignition engine. The engine operates at 1800 rpm with a compression ratio of 10:1, under two lean combustion conditions: excess air ratios of 2.5 and 1.7, at full and part load, respectively. The simulations were performed using the CONVERGE 3.1 software and the C3MechV3.3 reaction mechanism. The predictions were then compared with experimental data to assess the accuracy and validity of the model, enabling the comparison of different lean operating conditions to evaluate important combustion characteristics, such as flame development, apparent heat release and NOx formation. The tested model successfully validated the two experimental conditions, accurately adjusting the in-cylinder pressure profiles for both cases of lean hydrogen mixture combustion. Additionally, the prediction of the

França, Louise Bomfim Magalhães, Pasa, Bruno Roberto, Fagundez, Jean Lucca Souza, Pereira, Juliano Silveira, Martins, Mario Eduardo Santos, Lanzanova, Thompson Diórdinis Metzka, Salau, Nina Paula Gonçalves

Numerical Study of the Effect of Direct-Injection Timing of Methanol and Excess Air Ratio on the Combustion Characteristics of a Marine Diesel-Methanol Dual-Fuel Engine

2023-01-1626

10/31/2023

Methanol is a suitable alternative fuel to relieve the problem of energy shortage and decrease the emission of greenhouse gases. The effect of direct-injection timing of methanol and diesel on the combustion characteristics of a marine diesel engine with bore of 210 mm was simulated with a 3-dimentional computational fluid dynamic (CFD) software AVL-FIRE. The combustion model was set-up and validated by the experimental data from the marine diesel engine. Results show that there are two peaks on the heat release rate (HRR) curves with the normal diesel-methanol combustion process. The first HRR peak is caused by the combustion of diesel. The second HRR peak is resulted from the hybrid combustion process of diesel and methanol. The injection timing of diesel influences the peak pressure rise rate (PPRR) and ignition timing. The indicated mean effective pressure (IMEP), the maximum in-cylinder pressure and combustion duration are influenced by the direct-injection timing of methanol

Li, Xiao, Yan, Ping, Li, Hong-Mei, Zheng, Liang, Shen, Gang, Hu, Yu-Chen, Han, Dan

Numerical Research on the Effects of Pre-Chamber Orifice Scheme on the Performance in a Large-Bore Natural Gas Engine

2023-01-1631

10/31/2023

Pre-chamber ignition is one of the advanced technologies to improve the combustion performance for lean combustion natural gas engine, which could achieve low NOx, simultaneously. The designing scheme of the orifices, which connects the pre-chamber and the main chamber, is the main challenge limiting the further improvement. In this work, the three-dimensional computational fluid dynamics calculation based on a four-stroke engine with 320 mm cylinder bore was conducted to investigate the effects of orifice structure on the combustion and NOx performance. The results show that the schemes with 7 and 9 orifices lead to the delayed high-temperature jets formation due to the asymmetrical airflow in the pre-chamber, which retards the ignition timing but enhances the combustion in the main chamber. The 6 orifices scheme leads to the insufficient distribution of the high-temperature jets, and the 10 orifices result in the serious interference between the adjacent high-temperature jets. The

Li, Bo, Cao, Jianlin, Tian, Liu, Fan, Liyun, Xiao, Ge, Long, Wuqiang

A Novel Approach to Constructing Reactivity-Based Simplified Combustion Model for Dual Fuel Engine

2023-01-1627

10/31/2023

To achieve higher efficiencies and lower emissions, dual-fuel strategies have arisen as advanced engine technologies. In order to fully utilize engine fuels, understanding the combustion chemistry is urgently required. However, due to computation limitations, detailed kinetic models cannot be used in numerical engine simulations. As an alternative, approaches for developing reduced reaction mechanisms have been proposed. Nevertheless, existing simplified methods neglecting the real engine combustion processes, which is the ultimate goal of reduced mechanism. In this study, we propose a novel simplified approach based on fuel reactivity. The high-reactivity fuel undergoes pyrolysis first, followed by the pyrolysis and oxidation of the low-reactivity fuel. Therefore, the simplified mechanism consists of highly lumped reactions of high-reactivity fuel, radical reactions of low-reactivity fuel and C0-C2 core mechanisms. We have applied this methodology to a dual-fuel engine fueled with

Li, Ang, Zhang, Zhenyingnan, Li, Zhuohang, Zhu, Lei, Huang, Zhen

Effects of the Combustion Enhancer Containing Alkyl Nitrate (CEN) to Methanol in a Direct-Injection Compression Ignition (DICI) Engine

2023-01-1619

10/31/2023

When a biofuel, methanol is an interesting alternative for internal combustion engines (ICE). Despite drawbacks such as misfiring or instabilities at low loads, methanol has several advantages. Today, dual-fuel systems allow the use of methanol in combination with diesel fuel. This paper will present a different approach, the ability to use methanol in a flex-fuel system. The addition of a combustion enhancer containing alkyl nitrate (CEN) allows the use of methanol in a direct-injection compression ignition (DICI) engine without any changing. In this paper, different volume fractions of this additive are tested. The aim is to show the effect of the CEN on the combustion of methanol. The effect of CEN on methanol has been confirmed thanks to previous tests carried out on a Rapid Compression Machine (RCM). Ignition delay times (IDT) and auto-ignition temperature were reduced with small amounts of CEN. The engine is a single-cylinder, with a displacement of 0.499L and a compression ratio

Samson, Richard, Morin, Anne-Gaëlle, Foucher, Fabrice

Experimental Study of Combustion Characteristics and Emissions of Pre-Chamber Induced HCCI Combustion

2023-01-1623

10/31/2023

It is a well-known fact that HCCI combustion offers the possibility of achieving high efficiency with low emissions, but with the challenges in combustion control and ability to adjust to changing environmental conditions. To resolve the aforementioned challenges, a pre-chamber induced homogeneous charge compression ignition (PC-HCCI) combustion mode was experimentally tested with aim of providing initial operating boundaries in terms of combustion stability and obtaining initial performance results. The single cylinder engine equipped with active pre-chamber and compression ratio (CR) of 17.5 was fueled by gasoline. The initial experiments were performed at the engine speed of 1600 rpm with intake air temperatures varied from 33°C to 100°C to verify the possibility of achieving the PC-HCCI combustion mode and to compare the achieved engine performance and emission results with both PCSI and pure HCCI combustion modes used as reference cases. The results showed that PC-HCCI combustion

Ugrinić, Sara, Krajnovic, Josip, Sjeric, Momir, Kozarac, Darko

Simulation Study of the Effect of Nozzle Position and Hydrogen Injection Strategy on Hydrogen Engine Combustion Characteristic

2023-01-7018

10/30/2023

Hydrogen energy is a kind of secondary energy with an abundant source, wide application, green, and is low-carbon, which is important for building a clean, low-carbon, safe, and efficient energy system and achieving the goal of carbon peaking and being carbon neutral. In this paper, the effect of nozzle position, hydrogen injection timing, and ignition timing on the in-cylinder combustion characteristics is investigated separately with the 13E hydrogen engine as the simulation object. The test results show that when the nozzle position is set in the middle of the intake and exhaust tracts (L2 and L3), the peak in-cylinder pressure is slightly higher than that of L1, but when the nozzle position is L2, the cylinder pressure curve is the smoothest, the peak exothermic rate is the lowest, and the peak cylinder temperature is the lowest. When the ignition timing is consistent, with the delay of hydrogen injection timing, the peak in-cylinder pressure decreases and the peak phase remains

Tan, Piqiang, Tian, Yuan, Lou, Diming, Zhang, Yunhua, Liu, Dengcheng, Zhao, Keqin

Study on Knocking Intensity and Autoignitive Propagation Velocity with the Same Methane Number Mixtures of Methane/Ethane and Methane/ n -Butane

2023-01-1803

10/24/2023

Although methane number is widely used to predict knocking occurrence and its intensity, it does not determine a fuel composition uniquely, that means, the knocking intensity by the different composition fuel must show difference even if the same methane number fuels are employed. To establish a novel index, the knocking intensity and the autoignitive propagation velocity, as consequence of spontaneous ignition process, are investigated both experimentally and numerically by using the different composition gaseous fuels with same methane number. Methane/ethane/air and methane/n-butane/air mixtures with the same methane number of 70 and the equivalence ratio of 0.5 were employed. They are rapidly compressed and ignited spontaneously by a Rapid Compression Machine. Ignition delay times, autoignitive propagation velocities, and knocking intensity were measured by acquired pressure histories and high-speed imaging. To survey detail, zero-dimensional and quasi-one-dimensional numerical

Saito, Masanori, Kato, Ryo, Komatsu, Yuma, Takagi, Keigo, Otani, Masaki, Tanabe, Mitsuaki

Improvement of the EGR Dilution Tolerance in Gasoline Engines by the Use of a HSASI Pre-Chamber Spark Plug

2023-01-1805

10/24/2023

Charge dilution in gasoline engines reduces NOx emissions and wall heat losses by the lower combustion temperature. Furthermore, under part load conditions de-throttling allows the reduction of pumping losses and thus higher engine efficiency. In contrast to lean burn, charge dilution by exhaust gas recirculation (EGR) under stoichiometric combustion conditions enables the use of an effective three-way catalyst. A pre-chamber spark plug with hot surface-assisted spark ignition (HSASI) was developed at the UAS Karlsruhe to overcome the drawbacks of charge dilution, especially under part load or cold start conditions, such as inhibited ignition and slow flame speed, and to even enable a further increase of the dilution rate. The influence of the HSASI pre-chamber spark plug on the heat release under EGR dilution and stoichiometric conditions was investigated on a single-cylinder gasoline engine. The performance of the HSASI spark plug was compared with a passive pre-chamber spark plug

Holzberger, Sascha, Kettner, Maurice, Kirchberger, Roland

An Optimized, Data-Driven Reaction Mechanism for Dual-Fuel Combustion of Ammonia and Diesel Primary Reference Fuels

2023-32-0101

09/29/2023

The possibility to operate current diesel engines in dual-fuel mode with the addition of an alternative fuel is fundamental to accelerate the energy transition to achieve carbon neutrality. The simulation of the dual- fuel combustion process with 0D/1D combustion models is fundamental for the performance prediction, but still particularly challenging, due to chemical interactions of the mixture. The authors defined a novel data-driven workflow for the development of combustion reaction mechanisms and used it to generate a dual-fuel mechanism for Ammonia and Diesel Primary Reference Fuels (DPRF) suitable for efficient combustion simulations in heavy duty engines, with variable cetane number Diesel fuels. A baseline reaction mechanism was created by merging the detailed ammonia mechanism by Glarborg et al. with reaction pathways for n- hexadecane and 2,2,4,4,6,8,8-heptamethylnonane from a well-established multi-component fuel mechanism. To define its target validity space, a standardized

Perini, Federico, Reitz, Rolf D., Fiorini, Niccolò, Innocenti, Alessandro, Latinov, Matteo, Vichi, Giovanni

Study on the image recognition of ammonia ignition process induced by methanol micro-jet

2023-32-0067

09/29/2023

Ammonia is regarded as a possible carbon-free energy source for engines, drawing more and more attention. However, the low burning velocity of ammonia inhibits its application. To improve the ignition energy by ignition chamber (pre-chamber) jet ignition seems to be a good solution. In this study, the jet-controlled compound ignition (JCCI) model was proposed to improve the ammonia premixed combustion, in which the ignition chamber was fueled with methanol, investigated by visualization method in a constant volume chamber. Jet flame image recognition and characteristic parameters determination is significant to the analysis of the jet flame propagation and combustion processes. In this study, jet flame image recognition approaches were investigated and compared. The Approach 1 as jet flame contour extraction method was applied to study the overall jet flame propagation. Approach 2 focuses on the jet flame variation of the adjacent images to recognition the jet ignition process, which

Wang, Peng, Long, Wuqiang, Wei, Fuxing, Dong, Dongsheng, Tian, Hua, Tian, Jiangping, Dong, Pengbo, Zhang, Xiaolei, Lu, Mingfei

A Study of Autoignition and Combustion Characteristics in an HCCI Engine using a Blended Fuel of DME and City Gas

2023-32-0017

09/29/2023

In recent years, there has been a need to reduce CO2 emissions from internal combustion engines in order to achieve an energy-saving and low-carbon society. Against this backdrop, the authors have focused attention on Homogeneous Charge Compression Ignition (HCCI) combustion that achieves both high efficiency and clean emissions. With HCCI combustion, a premixed mixture of fuel and air is supplied to the cylinder and autoignited by piston compression to drive the engine. Autoignition makes it possible to operate the engine at a high compression ratio, enabling the HCCI combustion system to attain high efficiency. However, HCCI combustion also has some major unresolved issues. Two principal issues that can be cited are ignition timing control for igniting the mixture at the proper time and assurance of suitable combustion conditions following ignition to prevent incomplete combustion and knocking. The combustion characteristics of a blended fuel of dimethyl ether (DME) as the ignition

Yamagiwa, Reo, MANABE, Yusuke, MITO, Shinji, IIJIMA, Akira, YOSHIHARA, Shintaro, YAMAGUCHI, Takahiro, MIYAMOTO, Sekai

Numerical Investigation of Multi-Stage HCCI Combustion with Small Chamber Inside Piston

2023-32-0020

09/29/2023

Homogeneous charge compression ignition (HCCI) combustion is promising for not only high thermal efficiency but also reducing nitrogen oxides (NOx) and PM simultaneously. However, the operational range of the HCCI combustion is limited because of some issues, such as poor control of ignition timing and knocking by the excessive rate of pressure rise. In this study, a new combustion system based on the HCCI combustion process is proposed based on the authors' previous experimental work. This combustion system has a divided combustion chamber of two parts, one is small and the other is large. The most significant feature is the small chamber inside the piston. At first, combustion takes place in the small chamber, and then the burned gas is ejected into the large chamber to ignite the mixture in the large chamber. In this combustion system, the combustion in the large chamber takes the HCCI combustion process. 3D-CFD was conducted to predict HCCI combustion characteristics with small

Nomura, Takuya, Moriyoshi, Yasuo, Morikawa, Koji, Kuboyama, Tatsuya

Simulation of charged species flow and ion current detection for knock sensing in gasoline engines with active pre-chamber

2023-32-0005

09/29/2023

Recently, it has been wildly recognized that active pre- chamber has a significant effect on extending the lean burn limit of gasoline engines. Ion current signals in the combustion is also considered as a promising approach to the engine knock detection. In this study, the feasibility of employing ion current in an active pre- chamber for combustion diagnosis was analyzed by three-dimensional numerical simulation on a single- cylinder engine equipped with active pre-chamber. The flow characteristics of charged species (NO+, H3O+ and electrons) in the main chamber and pre-chamber under knock conditions are investigated at different engine speeds, intake pressures and ignition timings. The results show that the ion current can theoretically be used for the knock detection of the active pre- chamber. The peak value of the electron or H3O+ mass fraction caused by knocking backflow can be used as knock indication peak. Intake pressure is the most critical factor affecting the intensity of

MIAO, Xinke, FEI, Shengyi, DENG, Jun, LI, Liguang, HU, Yinuo, MA, Junjie

End-Gas Autoignition Prediction Using Reverse Livengood-Wu Integral with Ignition Delay Time Equations for Gasoline Surrogate Fuel

2023-32-0081

09/29/2023

A high-accuracy knocking or end-gas autoignition prediction model with low computational loads is necessary to develop thermal-efficiency improvement technologies for SI engines efficiently using computational techniques. Livengood-Wu integral has been applied widely as a simple and practical model to predict in-cylinder autoignition timing. In the present study, a high-accuracy model based on Livengood-Wu integral, has been investigated. First, a small set of ignition delay time equations for a premium-gasoline surrogate fuel has been developed, which can reproduce the temperature-, pressure-, equivalence ratio-, and EGR-dependences of ignition delay time under constant-volume condition, produced using a detailed reaction mechanism. Then, Livengood-Wu integral using the ignition delay time equations has been applied to predict in-cylinder autoignition timing produced using the detailed reaction mechanism. Numerical analyses have found X of Livengood-Wu integral and error factors in

Kuwahara, Kazunari

Ignition and Combustion Controls of Synthetic Fuel using Diesel Engine with Variable Valve Timing System [First Report

2023-32-0060

09/29/2023

Because the transportation industry uses fossil fuels as much as 1/4 of the total, CO2 emission from transport sector should be reduced. Therefore, carbon neutral (CN) fuel has been attracted attention. However, hydrogen and ammonia have low energy density and are difficult to be stored and transported. In this study, synfuel produced by Fischer-Tropsch (FT) reaction. This fuel is produced with carbon dioxide absorbed from the direct air capture and electricity derived from renewable energy, so it is possible to achieve CN. However, FT fuel tends to have less aromatics and a higher cetane number than diesel fuel. Therefore, excessive early ignition occurs at low speed and low load in application to diesel engine. The purpose of this study is to suppress early ignition by controlling the amount of air flowing into the cylinder. The numerical results showed that the ignition timing and combustion could be controlled using Miller cycle by late intake valve closing (LIVC). In addition, by

Sumida, Yo, Terada, Masaya, Kawano, Daisuke

Improvement in Oxy-fuel Combustion of SI Engine Fueled by Natural Gas

2023-32-0085

09/29/2023

Oxy-fuel combustion (OFC), in which fuel is burnt with pure oxygen, is a promising method by which to establish a CO2 recovery system from engine exhaust. The ideal exhaust gas for OFC consists of only CO2 and H2O at a stoichiometric mixture ratio, which can be easily separated by cooling the exhaust. In OFC, exhaust gas recirculation (EGR) is applied in order to avoid an extreme increase of the combustion temperature by increasing the heat capacity. In the present study, in order to improve the OFC of a natural-gas spark-ignited engine, the effect of the operating conditions on the combustion characteristics was investigated using a rapid compression and expansion machine. The effects of the compression ratio, ignition timing, and CO2 concentration in the mixture were examined while keeping the fuel-oxygen mixture at the stoichiometric ratio. The obtained results show that by increasing the compression ratio from 10.1 to 17.5, the gross indicated thermal efficiency of OFC can be

KAWASAKI, Kiyoshi, SUETOMI, Junya, YOKOE, Syunsuke, YAMANE, Koji, DEJIMA, Kazuhito

Numerical simulation of effects of operating parameters on combustion in a hydrogen direct injection engine

2023-32-0040

09/29/2023

In this study, a three-dimensional numerical model of a hydrogen direct injection engine was built, and the effects of several engine operating parameters, including equivalence ratio, injection timing, ignition timing and intake pressure on combustion were analyzed. The results show that with a fixed ignition timing and intake pressure of 1.0 bar, an increase in the equivalence ratio from 0.3 to 1.1 leads to a reduction in indicated thermal efficiency from 47.3% to 37.73% due to increasing wall heat loss. The NOX emissions first increase and then decrease, arriving the peak at the equivalence ratio of 0.7, about 20.9g/kW·h, primarily attributed to the combined effect of oxygen content, cylinder temperature, and hydrogen reducibility. When the equivalence ratio is fixed at 0.5, with the injection timing delayed, the stratification of the mixture becomes more obvious, the combustion speed accelerates, and the maximum thermal efficiency increases. At the same time, NOX emissions also

Zhen, Fu, Wenzhi, Gao, Duanzheng, Zhao, Yuhuai, Li

Development of a 5-Component Diesel Surrogate Chemical Kinetic Mechanism Coupled with a Semi-Detailed Soot Model with Application to Engine Combustion and Emissions Modeling

2023-24-0030

08/28/2023

In the present work, five surrogate components (n-Hexadecane, n-Tetradecane, Heptamethylnonane, Decalin, 1-Methylnaphthalene) are proposed to represent liquid phase of diesel fuel, and another different five surrogate components (n-Decane, n-Heptane, iso-Octane, MCH (methylcyclohexane), Toluene) are proposed to represent vapor phase of diesel fuel. For the vapor phase, a 5-component surrogate chemical kinetic mechanism has been developed and validated. In the mechanism, a recently updated H2/O2/CO/C1 detailed sub-mechanism is adopted for accurately predicting the laminar flame speeds over a wide range of operating conditions, also a recently updated C2-C3 detailed sub-mechanism is used due to its potential benefit on accurate flame propagation simulation. For each of the five diesel vapor surrogate components, a skeletal sub-mechanism, which determines the simulation of ignition delay times, is constructed for species C4-Cn. The five skeletal sub-mechanisms are coupled with the new C2

Yang, Shiyou, Yang, Ruicheng

Experimental Combustion Analysis in a Gasoline Baseline Hydrogen-Fueled Internal Combustion Engine at Ultra-Lean Conditions

2023-24-0073

08/28/2023

Hydrogen-fueled internal combustion engines (H2ICEs) have emerged as a promising technology for reducing greenhouse gas emissions in the transportation sector. However, due to the unique properties of hydrogen, especially under ultra-lean conditions, the combustion characteristics of hydrogen flames differ significantly from those of conventional fuels. This research focuses on evaluating the combustion process and cycle-to-cycle variations (CCVs) in a single-cylinder port-fuel injection H2ICE, as well as their impact on performance parameters. To assess in-cylinder combustion, three indicators of flame development are utilized and compared to the fundamental properties of hydrogen. The study investigates the effects of various factors including fuel-air equivalence ratio (ranging from 0.2 to 0.55), engine load (IMEP between 1 and 4 bar), and engine speed (900 to 1500 rpm). The analysis aims to understand the behavior of the flame initiation phase, which refers to the time from

Ramalho Leite, Caio, Laignel, Mathieu, Brequigny, Pierre, Borée, Jacques, Foucher, Fabrice

Piston Pre-Heating Using a Pressurized-Heated Oil Buffer: A Practical Method to Reduce ICE Emissions and Fuel Consumption

2023-24-0123

08/28/2023

Engine cold start is characterized by sub-optimal combustion efficiency due to the low temperature of the combustion chamber; this heavily increases engine raw emissions at start. One driving phenomenon is a limited fuel evaporation rate. Consequently, a liquid fuel film remains on the piston top at ignition. Liquid fuel deposited on the piston top is a well-known cause of “pool-fire”, leading to high levels of particle emissions; a problem particularly noticeable with bio-based renewable fuels. Engine piston pre-heating can be deployed to prevent or limit the formation of such fuel film and associated pollutants. In this work a practical technique is proposed to effectively pre-heat the pistons immediately before engine cold start. The device consists of a pressurized-heated oil buffer which pre-heats the pistons via the existing piston cooling nozzles. The device provides further benefits in emissions and fuel consumption in two ways: 1) the warm oil pre-lubricates the engine working

Bovo, Mirko, Mubarak Ali, Mohammed Jaasim

Influence of the Injection Timing on the Mixture Formation Process in a Spark-Ignition Hydrogen Fuelled ICE

2023-24-0079

08/28/2023

In the context of reducing carbon-dioxide (CO2) emissions, the increasing exploitation of renewable sources is expected to improve the availability of green hydrogen, which can be considered a valid alternative to gasoline and diesel fuels in the mobility sector (particularly for long-haul and heavy-duty missions). The air-hydrogen mixing plays a significant role, particularly in direct-injection spark-ignition engines. As a matter of fact, the onset of zones featuring an equivalence ratio greater than 0.5 should be avoided, since this would lead to an increased risk of self-ignition and NOx production. The presence of wide ultra-lean volumes (over the lean flammability limit) due to imperfect mixing is negative too, yielding to irregular combustion. Therefore, the calibration of the direct injection timing is a crucial task. In this work, the authors numerically explore the influence of the injection timing, for a fixed total amount of fuel (global equivalence ratio equal to 0.25), on

Anaclerio, Giuseppe, Capurso, Tommaso, Torresi, Marco, Camporeale, Sergio

Combustion, Performance, Emissions and Energy Analysis of Hydrogen Fuelled Spark-Ignition Engine under Lean Burn Condition

2023-28-1334

05/25/2023

The design and development of a hydrogen powered spark-ignition engine, aimed for installation on a vehicle for on-road application. The experiment was conducted at WOT (Wide Open Throttle) condition at a speed of 4000 rpm with an excess air-fuel ratio of 1.3, 1.5, 2.2, 2.5, 3, 3.75, and 4.0. The ignition timing was optimized for maximum torque at each value of the excess air ratio. The various parameters analyzed such as in-cylinder pressure, Pressure and Volume, Logarithm of Pressure and Volume, Mass fraction burned, Cummulative heat release, Net heat release, Rate of pressure rise, and Mean gas temperature. The results show that there is a profound effect of excess air-fuel ratio on the engine’s mean effective pressure, output power, Brake thermal efficiency, Volumetric efficiency, Brake specific fuel consumption, and NOx emissions. The peak cylinder pressure decreases with an increase in excess air-fuel ratio and NOx emissions are reduced due to reduced mean gas temperature. Also

Shinde, Apurwa, KARUNAMURTHY, K, SHINDE, BALU JALINDAR, Rairikar, Sandeep, Thipse, Sukrut S

Understanding Interaction between Reactive Jets in Pre-Chamber Ignition of Gaseous Fuel

2023-01-0225

04/11/2023

In order to improve the ignition capacity and burning rate for spark-ignited engines, pre-chamber jet ignition is a promising technique to achieve fast premixed combustion and low pollutant emissions. However, few studies focus on the interaction between multiple reacting (i.e. flamelet) or reacted (i.e. radical) jets, its effect on ignition, exotherm and flow behaviors also remain to be revealed. This paper investigated two types of jet interaction under different pre-chamber structures, including the jet-crossing and unequal nozzle designs. Optical experiments under different conditions were conducted in a constant volume combustion chamber with CH4 as fuel, using simultaneous high speed schlieren and OH* chemiluminescence method. Meanwhile, computational fluid dynamics (CFD) simulations with CH4 and NH3/CH4 blend fuels were carried out using Converge software to provide further insights of turbulent flow and ignition process. For the jet-crossing structure, it was found that

Zhang, Yixiao, Ma, Xiao, Mao, Jianshu, Fang, Yuwen, Li, Yanfei, Shuai, Shijin

Computational Investigation of Combustion Phasing and Emission of Ammonia and Hydrogen Blends under HCCI Conditions

2023-01-0189

04/11/2023

There is a growing interest in ammonia as a potential carbon-free fuel due to the current trend of decarbonization in ground transportation. Benefits of ammonia as a fuel include its high volumetric energy density, ease of storage and transportation, and mature manufacturing infrastructure. On the other hand, ammonia suffers from a low flame speed, long ignition delay times and NOx formation. In this work, a computational investigation of ammonia and hydrogen blends in a 0-D homogeneous charge compression ignition reactor is conducted using different blends under a range of engine-relevant conditions. Iso-contours of the crank angle corresponding to 50% of total heat release (CA50) are developed to assess the reactivity of the different blends under different engine speeds and equivalence ratios. The results show that ammonia requires a high inlet temperature to achieve a CA50 close to top dead center (TDC). An increase in hydrogen concentration resulted in a lower inlet temperature

Bakir, Ahmad, Ge, Haiwen, Zhao, Peng

An Updated Comprehensive Chemical Kinetic Mechanism for Ammonia and its Blends with Hydrogen, Methanol, and N -Heptane

2023-01-0204

04/11/2023

Ammonia is a promising carbon-free alternative fuel for use in combustion systems. The main associated challenges are its relatively low reactivity and high NOx emissions compared to conventional fuels. Therefore, the combustion behaviour of ammonia and ammonia blends still needs to be better understood over a wide range of conditions. To this end, a comprehensive chemical kinetic mechanism C3MechV3.4, which is an update of C3MechV3.3, has been developed for improved predictions of the combustion of ammonia and ammonia blends. C3MechV3.4 has been validated using a wide range of experimental results for pure ammonia and ammonia/hydrogen, ammonia/methanol and ammonia/n-heptane blends. These validations target different data sets including ignition delay times, species profiles measured as a function of time, and/or temperature and laminar flame speeds over a wide range of conditions. The updated developed mechanism gives good predictions for pure ammonia and its blends with hydrogen

Hamdy, Mohamed, Nadiri, Solmaz, Mohamed, Ahmed, Dong, Shijun, Wu, Yuxiang, Fernandes, Ravi, Zhou, Chongwen, Liu, Shuaishuai, Senecal, Kelly, Zhang, Kuiwen, Curran, Henry

Characterization of High-Tumble Flow Effects on Early Injection for a Lean-Burn Gasoline Engine

2023-01-0238

04/11/2023

The influence of early induction stroke direct injection on late-cycle flows was investigated for a lean-burn, high-tumble, gasoline engine. The engine features side-mounted injection and was operated at a moderate load (8.5 bar brake mean effective pressure) and engine speed (2000 revolutions per minute) condition representative of a significant portion of the duty cycle for a hybridized powertrain system. Thermodynamic engine tests were used to evaluate cam phasing, injection schedule, and ignition timing such that an optimal balance of acceptable fuel economy, combustion stability, and engine-out nitrogen oxide (NOx) emissions was achieved. A single cylinder of the 4-cylinder thermodynamic engine was outfitted with an endoscope that enabled direct imaging of the spark discharge and early flame development. Tejhese measurements were complemented by optical-engine tests used to directly measure the impact of fuel injection dynamics on late-cycle flows via a combination of particle

MacDonald, James Richard, White, Logan, Ekoto, Isaac, Pickett, Lyle, Oh, Heechang, Han, Donghee

Ignition Delay Time of a Toluene Reference Fuel with Substituted Phenol Additives

2023-01-0321

04/11/2023

Rapid compression machines can be used to measure a fuel’s ignition delay time and develop an understanding of its resistance to autoignition. Continuing developments in engine design demand higher octane fuels that are resistant to autoignition. Substituted phenols are members of the aromatic hydrocarbon family, and aromatics like toluene are often added to pump-grade gasoline to increase the fuel octane number. Previous numerical and experimental studies have found that substituted phenols included at additive levels in gasoline surrogates, such as the toluene reference fuel in this study, may have a lengthening effect on the ignition delay time of the base fuel they are added to. In this study, the substituted phenols 2,4-xylenol and 3,5-xylenol were added to their own respective toluene reference fuel at 2% by mole, and the ignition delay times of the base fuel mixtures including substituted phenols were compared to the base fuel without additives at engine-relevant conditions for

Trombley, Grace, Toulson, Elisa

Analysis of Cycle-to-Cycle Variation in In-Cylinder Flow and Combustion by Using Simultaneous PIV Measurements on Two Sections

2023-01-0215

04/11/2023

To realize stable combustion in lean or diluted conditions, reducing cycle-to-cycle variations of flow and fuel distribution is important. In this study, the effect of initial flow field was examined by simultaneous Time-Resolved PIV and visualization on two cross-sections in a fully optical-access engine under motoring and firing conditions with homogeneous pre-mixture. As a result, Omega index was defined and plotted on the correlation map between turbulence kinetic energy and CA10 (duration from ignition timing to 10% to the total accumulated heat). The omega index describes the strength of a horizontal flow field that resembles the shape of the Greek letter Omega. The plots with high Omega index were found frequently in the CA10 retarded cycles. On the other hand, the plots with low Omega index have simple tumble flows and the correlation was clearly found. This means that not only turbulence but also mean velocity’s pattern are important for the estimation parameter of cycle-to

Moriyoshi, Yasuo, Hokimoto, Satoshi, Kuboyama, Tatsuya, kaneko, Makoto

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