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Methodology to Determine the Fast Burn Period Inside a Heavy-Duty Diesel Engine Converted to Natural Gas Lean-Burn Spark Ignition Operation

West Virginia University-Jinlong Liu, Cosmin Dumitrescu
  • Technical Paper
  • 2019-01-2220
Published 2019-12-19 by SAE International in United States
The conversion of existing diesel engines to natural-gas operation can reduce the dependence on petroleum imports and curtail engine-out emissions. A convenient way to perform such conversion is by adding a gas injector in the intake manifold and replacing the diesel fuel injector with a spark plug to initiate and control the combustion process. However, challenges may appear with respect to engine’s efficiency and emissions as natural-gas spark-ignition combustion inside a diesel combustion chamber is different to that in conventional spark ignition engines. For example, major difference is the phasing and duration of the fast burn, defined as the period in which the rate of heat release increases linearly with crank angle. This study presents a methodology to investigate the fast burn inside a diesel geometry using heat release data. The algorithm was applied to experimental data from a single-cylinder research engine that operated at several lean-burn conditions that changed spark timing, equivalence ratio, and engine speed. More, a 3D CFD RANS engine simulation was used to validate the developed methodology. As results showed that…
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Plasma Temperature of Spark Discharge in a Lean-burn Spark-ignition Engine Using a Time Series of Spectra Measurements

Kyushu University-Yukihide Nagano, Toshiaki Kitagawa
Okayama University-Nobuyuki Kawahara, Masanobu Watanabe, Eiji Tomita
  • Technical Paper
  • 2019-01-2158
Published 2019-12-19 by SAE International in United States
In this research, a spark plug with an optical fiber has been developed to obtain the emission spectra from the spark discharge and flame kernel. This developed spark plug with an optical fiber can obtain the time series of emission spectra from the spark discharge and Initial flame kernel in the real spark-ignition engine using EMCCD spectrometer. The plasma vibrational temperature of the spark discharge can be measured using the emission spectra from the electrically excited CN violet band system. The plasma of the spark discharge and gas rotational temperature of the initial flame kernel can be also measured using emission spectra from OH* radicals (P and R branches). The plasma temperature of the spark discharge was almost 8,000 K and the gas temperature of the Initial flame kernel approached that of the adiabatic flame temperature.
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Specifics of the Combustion Phenomenon Inside a Heavy-Duty Diesel Engine Converted to Natural Gas Lean-Burn Spark Ignition Operation

Center for Alternative Fuels Engines and Emissions (CAFEE),-Jinlong Liu, Cosmin E. Dumitrescu, Hemanth Bommisetty
  • Technical Paper
  • 2019-01-2221
Published 2019-12-19 by SAE International in United States
The conversion of existing diesel engines to natural gas with the least amount of modifications can reduce the dependence on conventional oil and enhance national energy security. This study investigated such engine conversion using an experimental platform that consisted of a single-cylinder diesel engine modified for lean-burn natural-gas spark-ignition operation through the addition of a gas injector and a spark plug. Following steady-state experiments at several operating conditions that changed spark timing, mixture equivalence ratio, and engine speed, the experimental results suggested that the combustion phenomena in diesel engines retrofitted to lean-burn natural gas spark ignition presents significant differences compared to that in a conventional stoichiometric spark ignition engine. For example, the apparent heat release rate inferred from recorded pressure data is the addition of two separate, sequential combustion events: a fast burn inside the piston bowl and a slow event inside the squish region. To model the heat release in such converted engine, each combustion event was approximated to a Gaussian curve, with the total heat release during the engine cycle being the superimposition…
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Research of Fuel Components to Expand lean-limit in Super lean-burn condition

JXTG Nippon Oil & Energy Corporation-Taketora Naiki, Ken Obata, Manabu Watanabe
Keio University-Takeshi Yokomori, Norimasa Iida
  • Technical Paper
  • 2019-01-2257
Published 2019-12-19 by SAE International in United States
The thermal efficiency of internal combustion engines can be improved dramatically with the right combination of engine technology and fuel technology. Super lean-burn technology is attracting attention as a means of boosting thermal efficiency. However, there is a limit to how lean a fuel-air mixture can be before combustion becomes unstable or misfire occurs. The authors evaluated the effects of various chemical compositions on the lean limit under super lean-burn conditions. By changing the composition of the fuel, it was possible to achieve excess air ratios of over 2.0, resulting in high thermal efficiency.
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H2-Engine Operation with EGR Achieving High Power and High Efficiency Emission-Free Combustion

KEYOU GmbH-Daniel Thomas Koch, Alvaro Sousa, Dominik Bertram
  • Technical Paper
  • 2019-01-2178
Published 2019-12-19 by SAE International in United States
Using hydrogen as a fuel to power internal combustion engines is a practical and effective solution to achieve zero impact mobility. The product of hydrogen combustion is water vapour. It does not emit climate-damaging greenhouse gas CO2 and health-damaging pollutants such as CO, HC or NOx. The impact into the environment is negligible. This allows therefore zero impact mobility, as long as hydrogen fuel being produced from renewable energies and water. Hydrogen combustion strategies take the avoidance of NOx formation is a priority parameter to control.The idea of using hydrogen in combustion engines to power vehicles is not new and has been successfully demonstrated in the recent past by companies such as BMW, MAN and Ford.The Start-up company KEYOU is bringing hydrogen engines technology to a new level now by presenting a new combustion concept that is applied ‘add-on’ to existing Diesel engines. The result is an attractive clean engine solution to power clean vehicles, especially in the heavy-duty vehicle sector, where current clean solutions (such as battery electric or fuel cell electric) penalize customers…
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Study of Ignition Processes of a Lean Burn Engine using Large-Eddy Simulation

FEV Europe GmbH, Neuenhofstraße 181 , 52078 Aachen, Germany-P. Adomeit, A. Brunn
IFP Energies nouvelles, 1 et 4 avenue de Bois-Préau, 92852 R-S. Jay, K. Truffin, C. Angelberger
  • Technical Paper
  • 2019-01-2209
Published 2019-12-19 by SAE International in United States
Ultra-lean burn conditions (λ>1.8) is seen as a way for improving efficiency and reducing emissions of spark-ignition engines. In comparison to conventional operation with stoichiometric mixture, this itself raises fundamental issues in terms of combustion physics, among which the significant reduction of the laminar flame speed, increase of the laminar flame thickness as well as an increased sensitivity to local fuel/air equivalence ratio variations are all essential to be accounted for. In particular, the effect of modified laminar flame characteristics on flame stretch during the early flame development in a spark ignited engine is of importance.In the present work the cycle-to-cycle combustion variations of ultra-lean burn operation is modeled, by utilizing capability of Large-Eddy Simulation (LES). Then results are analyzed after a careful validation of the aerodynamics and spray/flow interactions that have initially been predicted. This aims to simulate direct injection gasoline engine operating in ultra-lean conditions with indicated efficiency of 46%.First, LES predictions of the cold flow are compared to High Speed Particle Image Velocimetry. Second, the injector model is compared against experimental spray…
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Hydrogen as a Combustion Enhancer for Highly Efficient Ultra-Lean Spark-Ignition Engines

IFP Energies nouvelles, Institut Carnot IFPEN TE-Jean-Marc Zaccardi, Guillaume Pilla
  • Technical Paper
  • 2019-01-2258
Published 2019-12-19 by SAE International in United States
Performance of lean burn gasoline spark-ignition engines can be enhanced through hydrogen supplementation. Thanks to its physicochemical properties, hydrogen supports the flame propagation and extends the dilution limits with improved combustion stability. These interesting features usually result in decreased emissions and improved efficiencies which is of the utmost importance for future SI engines targeting ultra-lean conditions at λ ≥ 2 and brake thermal efficiencies above 50%. Compared to previous studies of hydrogen supplementation, this article aims at demonstrating how hydrogen can support the combustion process with a modern combustion system optimized for extreme dilution rates and high efficiency.Experimental investigations performed with a single cylinder engine are reported and show that the minimal amount of hydrogen required to reach λ = 2 is in the range of 2 to 4% of the total intake volume flow rate. At low load, NOx emissions can be lowered down to 33 ppm at λ = 2 and results also show that a10-fold decrease in NOx emissions is possible when the dilution rate increases from the lean limit without hydrogen…
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Ignition Experiments by Nanosecond Repetitively Pulsed Discharges in Intense Turbulence for Super Lean Burn at Engine Condition

Institute of Fluid Science, Tohoku University-Kodai Uesugi, Youhi Morii, Taichi Mukoyama, Takuya Tezuka, Susumu Hasegawa, Hisashi Nakamura, Hidemasa Takana
Institute of Fluid Science, Tohoku University / ICE Lab. Far-Kaoru Maruta
  • Technical Paper
  • 2019-01-2160
Published 2019-12-19 by SAE International in United States
Ignition by Nanosecond Repetitively Pulsed Discharges (NRPD) at EXponential Increase of Minimum Ignition Energy (MIE-EXI) region under super lean SI engine conditions was studied. Fundamental experiments were conducted with a turbulent ignition test chamber with twin counter-rotating fans. The MIE-EXI region by arc discharge appeared over 6500 rpm of fan speed. In the MIE-EXI region (7000 rpm), successful ignition was achieved by establishing coupled ignition kernels with NRPD at 15 kHz although ignition was unsuccessful at 1 kHz. Results show that ignition by NRPD has potential advantages for lean burn applications. Preliminary engine test results with NRPD were also demonstrated.
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Influence of ethanol blending on knocking in a lean burn SI engine

Keio University-Kazuki Kaneko, Yuki Yasutake, Takeshi Yokomori, Norimasa Iida
  • Technical Paper
  • 2019-01-2152
Published 2019-12-19 by SAE International in United States
Lean burn is one method for improving thermal efficiency in spark ignition (SI) engines. Suppression of knocking provides higher thermal efficiency, and ethanol blending is considered an effective way to suppress knocking due to its high octane and high latent heat of evaporation.We investigate the effect of ethanol blending on knocking in an SI engine under lean operating conditions. The Livengood-Wu (LW) integral was performed based on ignition delay duration estimated from a zero-dimensional detailed chemical reaction calculation with pressure and temperature histories.Knocking was suppressed and thermal efficiency increased with ethanol-gasoline blending fuel, even at 0.5 equivalence ratio. Decrease in unburned gas temperature by latent heat of evaporation had a comparable influence on knocking suppression, which was supported by LW integral analysis.
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1D Numerical and Experimental Investigations of an Ultralean Pre-chamber Engine

SAE International Journal of Engines

Business Unit Gasoline Powertrains FEV Europe GmbH in Aachen, Germany-Christoph Müller, Knut Habermann
Universita degli Studi di Napoli Federico II Dipartimento di Ingegneria Industriale, Italy-Vincenzo De Bellis
  • Journal Article
  • 03-13-02-0012
Published 2019-11-19 by SAE International in United States
In recent years, lean-burn gasoline Spark-Ignition (SI) engines have been a major subject of investigations. With this solution, in fact, it is possible to simultaneously reduce NOx raw emissions and fuel consumption due to decreased heat losses, higher thermodynamic efficiency, and enhanced knock resistance. However, the real applicability of this technique is strongly limited by the increase in cyclic variation and the occurrence of misfire, which are typical for the combustion of homogeneous lean air/fuel mixtures. The employment of a Pre-Chamber (PC), in which the combustion begins before proceeding in the main combustion chamber, has already shown the capability of significantly extending the lean-burn limit. In this work, the potential of an ultralean PC SI engine for a decisive improvement of the thermal efficiency is presented by means of numerical and experimental analyses. The SI engine is experimentally investigated with and without the employment of the PC with the aim to analyze the real gain of this innovative combustion system. For both configurations, the engine is tested at various speeds, loads, and air-fuel ratios. A…