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A New Efficient Combustion Method for ICEs

Revolutionary Engines LLC-Peter C. Cheeseman
  • Technical Paper
  • 2020-01-1314
To be published on 2020-04-14 by SAE International in United States
The best known methods for combustion in Internal Combustion Engines (ICEs) are: Spark Ignition (SI), Compression Ignition (CI) and Homogeneous Charge Compression Ignition (HCCI). Each of these combustion methods has well known limitations for efficiency and clean exhaust. This paper presents a new method of combustion, called Entry Ignition (EI) that overcomes some of these limitations. EI burns a homogeneous fuel air mixture at constant pressure with combustion occurring at the inlet where the unburned mixture flows into the combustion chamber. Combustion results from the unburned mixture mixing with the much hotter burned gases already in the combustion chamber. EI can operate in a conventional piston-type engine, with the only major change being in the valving. EI’s efficiency gain results from the following. Firstly, EI is not subject to “knocking” and so can operate at CI-level compression ratios or higher. Secondly, EI allows lean burn, which improves efficiency for basic thermodynamic reasons. Thirdly, an engine using EI can fully expand the combustion gases (Brayton cycle), and finally, EI has reduced heat loss relative to the…
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Combustion Characterization of Neat n-Butanol in an SI Engine

Shanghai Jiao Tong University-Tie Li
University of Windsor-Navjot Singh Sandhu, Xiao Yu, Simon Leblanc, Ming Zheng, David Ting
  • Technical Paper
  • 2020-01-0334
To be published on 2020-04-14 by SAE International in United States
Increasingly stringent emission standards have promoted the interest in alternate fuel sources. Because of the comparable energy density to the existing fossil fuels and renewable production, alcohol fuels may be a suitable replacement, or an additive to the gasoline/diesel fuels to meet the future emission standards with minimal modification to current engine geometry. In this research, the combustion characteristics of neat n-butanol are analyzed under spark ignition operation using a single cylinder SI engine. The fuel is injected into the intake manifold using a port-fuel injector. Two modes of charge dilution were used in this investigation to test the limits of stable engine operation, namely lean burn using excess fresh air and exhaust gas recirculation (EGR). The in-cylinder pressure measurement and subsequently, heat release analysis are used to investigate the combustion characteristics of the fuel under low load SI engine operation. Additionally, a comprehensive emission analysis is performed to study the combustion by-products. Furthermore, the combustion and emission characteristics of n-butanol fuel are compared to those of the gasoline fuel. Preliminary results highlight the effect…
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Design and Simulation of a Multi Fuel Gas Mixture System of a Wankel Rotary Engine

University of Applied Sciences Zwickau-Tobias Dost, Joern Getzlaff
  • Technical Paper
  • 2020-01-0548
To be published on 2020-04-14 by SAE International in United States
The paper first includes the main objective and boundary conditions for design and simulation of a multi fuel gas mixture system of a Wankel rotary engine. New regenerative fuels are more and more important for use in automotive propulsion and stationary applications of combustion engines. Due to the special design and operation of rotary engines there are opportunities for running these engines in future electric and hybrid applications with new designed liquids and gaseous fuels based on regenerative energy sources. Nevertheless, rotary engines have advantages in avoidance of preignition and detonation especially when using gaseous fuels with a higher percentage of hydrogen. The focus is on basic research and analyses of main physical and thermodynamic properties of separate lean burn gases (lower calorific value, mixed calorific value, AFR) and their effects on fuel mixing and engine performance. Furthermore, the scope of the investigation is on the development of simulation models, which are capable to simulate the entire engine process and to map all factors influencing mixture formation, and for the combustion important parameter of unconventional…
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Combustion Enhancement in a Gas Engine Using Low Temperature Plasma

Chiba University-Yasuo Moriyoshi, Tatsuya Kuboyama
Oita University-Kimitoshi Tanoue
  • Technical Paper
  • 2020-01-0823
To be published on 2020-04-14 by SAE International in United States
Low temperature plasma ignition has been proposed as a new ignition technique as it has features of good wear resistance, low energy release and combustion enhancement. In the authors’ previous study, lean burn limit could be extended slightly by low temperature plasma ignition while the power supply’s performance with steep voltage rising with time (dV/dt), showed higher peak value of the rate of heat release and better indicated thermal efficiency. In this study, basic study of low temperature plasma ignition system was carried out to find out the reason of combustion enhancement. Moreover, the durability test of low temperature plasma plug was performed to check the wear resistance.
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Effect of Pre-Chamber Enrichment on Lean Burn Pre-Chamber Spark Ignition Combustion Concept with a Narrow-Throat Geometry

King Abdullah University of Science & Technology-Ponnya Hlaing, Manuel Echeverri Marquez, Eshan Singh, Fahad Almatrafi, Moez Ben Houidi, Bengt Johansson
Saudi Aramco-Emre Cenker
  • Technical Paper
  • 2020-01-0825
To be published on 2020-04-14 by SAE International in United States
Pre-chamber spark ignition (PCSI) combustion is an emerging lean-burn combustion mode capable of extending the lean operation limit of an engine. The favorable characteristic of short combustion duration at the lean condition of PCSI results in high efficiencies compared to conventional spark ignition combustion. Since the engine operation is typically lean, PCSI can significantly reduce engine-out NOx emissions while maintaining short combustion durations. In this study, experiments were conducted on a heavy-duty engine at lean conditions at mid to low load. Two major studies were performed. In the first study, the total fuel energy input to the engine was fixed while the intake pressure was varied, resulting in varying the global excess air ratio. In the second study, the intake pressure was fixed while the amount of fuel was changed to alter the global excess air ratio. At each global excess air ratio, the fuel injection to the pre-chamber was varied parametrically to assess the effect of pre-chamber enrichment on engine operating characteristics. Multi-chamber heat release analysis was performed to present the pre-chamber and main…
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The Potential of Gasoline Fueled Pre Chamber Ignition Combined with Elevated Compression Ratio

Hitachi Europe GmbH-Henning Sauerland
Technische Universitat Munchen-Andreas Stadler, Martin Härtl, Georg Wachtmeister
  • Technical Paper
  • 2020-01-0279
To be published on 2020-04-14 by SAE International in United States
Pre-chamber ignition is a method to simultaneously increase the thermal efficiency and to meet ever more stringent emission regulations at the same time. In this study, a single cylinder research engine is equipped with a tailored pre-chamber ignition system and operated at two different compression ratios, namely 10.5 and 14.2. While most studies on gasoline pre-chamber ignition employ port fuel injection, in this work, the main fuel quantity is introduced by side direct injection into the combustion chamber to fully exploit the knock mitigation effect. Different pre-chamber design variants are evaluated considering both unfueled and gasoline-fueled operation. As for the latter, the influence of the fuel amount supplied to the pre-chamber is discussed. Due to its principle, the pre-chamber ignition system increases combustion speeds by generating enhanced in-cylinder turbulence and multiple ignition sites. This property proves to be an effective measure to mitigate knocking effects. It is shown that less spark retard compared to conventional spark ignition allows to exploit the efficiency benefit of elevated compression ratios also in high load operation for stoichiometric mixtures.…
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Experimental and Numerical Analysis of Passive Pre-Chamber Ignition with EGR and Air Dilution for Future Generation Passenger Car Engines

DEA-IRP Groupe Renault-Cedric Libert, Fano Rampanarivo, Chistou Panagiotis, Maziar Dabiri
Universitat Politecnica de Valencia-Ricardo Novella, Jose Pastor, Josep Gomez-Soriano, Ibrahim Barbery
  • Technical Paper
  • 2020-01-0238
To be published on 2020-04-14 by SAE International in United States
Nowadays the combination of strict regulations for pollutant and CO2 emissions, together with the irruption of electric vehicles in the automotive market, is arising many concerns for internal combustion engine community. For this purpose, many research efforts are being devoted to the development of a new generation of high-performance spark-ignition (SI) engines for passenger car applications. Particularly, the PC ignition concept, also known as Turbulent Jet Ignition (TJI), is the focus of several investigations for its benefits in terms of engine thermal efficiency. The passive or un-scavenged version of this ignition strategy does not require an auxiliary fuel supply inside the PC; therefore, it becomes a promising solution for passenger car applications as packaging and installation are simple and straightforward. Moreover, combining this concept with lean burn is an interesting alternative for both improving the engine efficiency and maintaining low pollutant emissions as it enables Low Temperature Combustion (LTC) which ultimately reduces NOX emissions. EGR dilution is also an attractive approach as it is compatible with the three-way catalyst for NOX control. However, previous researches…
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Discharge Current Management for Diluted Combustion under Forced Flow Conditions

University of Windsor-Zhenyi Yang, Linyan Wang, Navjot S. Sandhu, Xiao Yu, Ming Zheng
  • Technical Paper
  • 2020-01-1118
To be published on 2020-04-14 by SAE International in United States
Lean burn or EGR diluted combustion with enhanced charge motion is effective in improving the efficiency of spark ignition engines. However, the ignition process under these conditions is getting more challenging due to higher ignition energy required by the lean or diluted mixture, as well as the interactions of the gas flow on the flame kernel. Enhanced spark discharge energy is essential to initiate the combustion under these conditions. Moreover, the discharge process should be more carefully controlled to improve the effectiveness of the spark. In this study, spark ignition systems with boosted discharge energy are used to ignite diluted air-fuel mixture under forced flow conditions. The impacts of the discharge current level, the discharge duration and the discharge current profile on the ignition are investigated in detail using optical diagnosis. It is evident from the results that extended discharge duration helps promote the flame propagation, though the effectiveness is limited when the duration exceeds the required minimum value for a self-sustained flame kernel. A higher discharge current level is favorable for generating a stronger…
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Experimental Investigation of the Influence of Ignition System Parameters on Combustion in a Rapid Compression-Expansion Machine

Graz University of Technology-Andreas Nickl, Andreas Wimmer
HOERBIGER Wien GmbH-Georg Meyer
  • Technical Paper
  • 2020-01-1122
To be published on 2020-04-14 by SAE International in United States
Lean burn combustion concepts with high mean effective pressures are being pursued for large gas engines in order to meet future stringent emission limits while maintaining high engine efficiencies. Since severe boundary conditions for the ignition process are encountered with these combustion concepts, the processes of spark ignition and flame initiation are important topics of applied research, which aims to avoid misfiring and to keep cycle-to-cycle combustion variability within reasonable limits. This paper focuses on the fundamental investigation of early flame kernel development using different ignition system settings. The investigations are carried out on a rapid compression-expansion machine in which the spark ignition process can be observed under engine-like pressure and excess air ratio conditions while low flow velocities are maintained. The schlieren setup for high-speed optical investigations of the area of the spark plug electrodes is described and a suitable post-processing routine is introduced. The influence of different spark current durations on early flame kernel formation is investigated using a modulated capacitive discharge ignition (MCDI) system. The outcomes reveal that a short spark current…
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High Resolution Global NOx Sub-Model for Embedded System Application with Low Calibration Effort

Exothermia GmbH-Konstantinos Michos
Technische Hochschule Nuernberg-Georgios Bikas, Peter Weigand, Marina Brilz
  • Technical Paper
  • 2020-01-0246
To be published on 2020-04-14 by SAE International in United States
The starting point of the present work is a global model of NOx formation for stoichiometric and lean combustion of hydrocarbons developed on the basis of a single non-linear algebraic equation. The latter is the exact solution of a system of differential equations describing the main kinetic reaction schemes of NOx formation, because it’s been analytically derived. The NOx sub-model incorporates the well-established thermal (extended Zeldovich) and the N2O reaction paths, which are considered to be the most relevant NOx production paths under certain operating conditions in arbitrary engine application. Furthermore, the NOx sub-model proposed here relies on well-established and adopted mechanisms like the GRI-Mech 3.0 [25] and consequently requires no parameter adjustment.The single equation NOx sub-model has been developed by the authors in a previous study [14] and shown satisfactory results when validated against test bench data of two different engines operated under stoichiometric and lean burn combustion conditions respectively. Therefore, there is a strong evidence, that its implementation on embedded systems for "in-situ" and "in memory" analysis of engine process data, or even…