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Experimental and Numerical Assessment of Active Pre-chamber Ignition in Heavy Duty Natural Gas Stationary Engine

Istituto Motori CNR-Gessica Onofrio, Carlo Beatrice
Lund University-Changle Li, Pablo Garcia Valladolid, Per Tunestal
  • Technical Paper
  • 2020-01-0819
To be published on 2020-04-14 by SAE International in United States
Gas engines (fuelled with CNG, LNG or Biogas) for generation of power and heat are, to this date, taking up larger shares of the market with respect to diesel engines. In order to meet the limit imposed by the TA-Luft regulations on stationary engines, lean combustion represents a viable solution for achieving lower emissions as well as efficiency levels comparable with diesel engines. Leaner mixtures however affect the combustion stability as the flame propagation velocity and consequently heat release rate are slowed down. As a strategy to deliver higher ignition energy, an active pre-chamber may be used. This work focuses on assessing the performance of a pre-chamber combustion configuration in a stationary heavy-duty engine for power generation, operating at different loads, air-to-fuel ratios and spark timings. The engine was originally a 6-cylinder compression ignition engine which is here employed as a single cylinder engine and then suitably modified to host the pre-chamber (with its natural gas injection system and spark plug) with a new bowl piston to decrease compression ratio. A 0D model is built…
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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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Review of Vehicle Engine Efficiency and Emissions

Corning, Inc.-Ameya Joshi
  • Technical Paper
  • 2020-01-0352
To be published on 2020-04-14 by SAE International in United States
This review covers some of the major advances pertaining to reducing tailpipe emissions of greenhouse gases and criteria pollutants. Discussed are both new and upcoming regulations, and technologies being developed for improving engines and after-treatment systems.There is clearly a focus on reducing greenhouse gas emissions in major countries, implemented through ambitious CO2 and electrification targets. Several mature IC engine (ICE) technologies are reviewed which promise to deliver double digit reductions in CO2 emissions. We cover some of these in detail, including gasoline compression ignition, pre-chamber combustion, water injection, and cylinder deactivation. Electrification of the powertrain and synergistic gains with advanced engine technologies are examined. The case is made for the need for cradle-to-grave analyses when evaluating various powertrain choices, and highlight the role hybrids can play in achieving significant and immediate CO2 reductions. For the first time, also briefly discussed are the role of advanced fuels and their potential for improving emissions.On criteria pollutants, the focus remains on reducing NOx and particulates. California is leading the charge on an omnibus rulemaking for heavy-duty trucks, targeting…
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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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Quasi-Dimensional Multi-Zone Combustion Diagnostic Tool for SI Engines with Novel NOx and CO Emissions Models

Exothermia GmbH-Konstantinos N. Michos
Technische Hochschule Nuernberg-Georgios Bikas
  • Technical Paper
  • 2020-01-0289
To be published on 2020-04-14 by SAE International in United States
In this work a quasi-dimensional multi-zone combustion diagnostic tool for homogeneous charge Spark Ignition (SI) engines is analytically developed for the evaluation of heat release, flame propagation, combustion velocities as well as engine-out NOx and CO emissions, based on in-cylinder pressure data analysis. The tool can be used to assess the effects of fuel, design and operating parameters on the SI engine combustion and NOx and CO emissions formation processes.Certain novel features are included in the presently developed combustion diagnostic tool. Firstly, combustion chambers of any shape and spark plug position can be considered due to an advanced model for the calculation of the geometric interaction between a spherically expanding flame and a general combustion chamber geometry. Also, the temperature stratification of the burned gas developed during the combustion phase, which has to be captured for the theoretically realistic estimation of the in-cylinder formation of pollutant emissions, is taken into account by a multi-zone thermodynamic treatment. According to this, multiple spherically allocated burned zones are sequentially generated at specified (user-defined) crank angle intervals, forming overlapping…
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Improving Heavy Duty Natural Gas Engine Efficiency: A Systematic Approach to Application of Dedicated EGR

Southwest Research Institute-Michael C. Kocsis, Robert Mitchell, Ahmed Abdul Moiz, Vickey Kalaskar, D. Ryan Williams, Scott Sjovall
  • Technical Paper
  • 2020-01-0818
To be published on 2020-04-14 by SAE International in United States
The worldwide trend of tightening CO2 emissions standards and desire for near zero emissions is driving development of high efficiency natural gas engines for a low CO2 replacement of traditional diesel engines. A Cummins Westport ISX12 G was previously converted to a Dedicated EGR® (D-EGR®) configuration with two out of the six cylinders acting as the EGR producing cylinders. Using a systems approach, the combustion and turbocharging systems were optimized for improved efficiency while maintaining the potential for achieving 0.02 g/bhp-hr NOX standards. A prototype variable nozzle turbocharger was selected to maintain the stock torque curve. The EGR delivery method enabled a reduction in pre-turbine pressure as the turbine was not required to be undersized to drive EGR. A high energy Dual Coil Offset (DCO®) ignition system was utilized to maintain stable combustion with increased EGR rates. High compression ratio, reduced squish pistons were designed to maintain MBT combustion phasing and fast burn rates along the torque curve. The final engine configuration was tested on the Heavy-Duty Supplemental Emissions Test (SET), a 13-mode steady-state engine…
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Predicting the Influence of Charge Air Temperature Reduction on Engine Efficiency, CCV and NOx-Emissions of a Large Gas Engine Using a SI Burn Rate Model

Caterpillar Energy Solutions GmbH-Stefan Palaveev, Matthias Veltman
FKFS-Sebastian Hann, Michael Grill
  • Technical Paper
  • 2020-01-0575
To be published on 2020-04-14 by SAE International in United States
In order to meet increasingly stringent exhaust emission regulations, new engine concepts need to be developed. Lean combustion systems for stationary running large gas engines can reduce raw NOx-emissions to a very low level and enable the compliance with the exhaust emission standards without using a cost-intensive SCR-aftertreatment system. Experimental investigations in the past have already confirmed that a strong reduction of the charge air temperature even below ambient conditions by using an absorption chiller can significantly reduce NOx emissions. However, test bench operation of large gas engines is costly and time-consuming. To increase the efficiency of the engine development process, the possibility to use 0D/1D engine simulation prior to test bench studies of new concepts is investigated using the example of low temperature charge air cooling. In this context, a reliable prediction of engine efficiency and NOx-emissions is important. Furthermore, restrictions to the engine operation like increase of cycle-to-cycle fluctuations due to high excess air ratio or late combustion need to be predicted as well in the engine simulation.For this purposes, a combustion model…
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Study for Higher Efficiency and Lower Emissions in Turbo Charged Small Gas Engine Using Low Caloric Biomass Model Gas

Doshisha University-Kenta Shiomi, Ryogo Kato, Eriko Matsumura, Jiro Senda
Yanmar Co.,Ltd-Ryoichi Hagiwara, Yuta Watanabe, Toru Nakazono
  • Technical Paper
  • 2019-32-0620
Published 2020-01-24 by Society of Automotive Engineers of Japan in Japan
In recent years, depletion of energy resources and increasing CO2 emission have been concerned. As this solution, the use of biofuels from garbage is focused. In this research, higher efficiency and lower emissions in the gas engine for power generation using biomass gas are aimed. However, the biomass gas is low caloric value and the output is low and the combustion is unstable. Therefore, a turbocharged spark ignition gas engine is used as the test institution. As a result, it is found that combustion stability and high efficiency of biomass gas can be realized.
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Experimental analysis of engine cooling capacity at different altitudes: a case study for biarticulated gas engine bus at high altitude

Scania Latin America-Gabriel Prado de Oliveira, Bruno Afonso Garcia
  • Technical Paper
  • 2019-36-0272
Published 2020-01-13 by SAE International in United States
The demand for mass public transportation is growing on the major urban areas worldwide along with stricter demands on exhaust gas emission levels driven by society’s concern on the environment, leading to the development of sustainable transport solutions. Some of the solutions to reduce emission levels, such as electrified powertrains, may not be affordable for emergent markets due to the necessity of investments on infrastructure as well as high costs of some technologies. Bogotá city in Colombia is renewing its bus rapid transit (BRT) fleet and aims to reduce emission levels in its operation. Therefore, the development of a biarticulated bus driven by a compressed natural gas (CNG) Otto engine can be a sustainable solution for such application reducing both emission levels and fuel costs (compared to a Diesel model). However, the development of a cooling system for such bus becomes a challenge due to several factors that have a negative impact on cooling performance such as: high gross train weight (GTW); high altitude application; CNG Otto engine (compared to a Diesel model) and limited…
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Experimental Investigation on the Influence of Brake Mean Effective Pressures up to 30 bar on the Behavior of a Large Bore Otto Gas Engine

Technical University of Munich-Stefan Eicheldinger, Tomas Bartkowski, Alexander Schröder, Dr.-Ing. Maximilian Prager, Prof. Dr.-Ing. Georg Wachtmeister
  • Technical Paper
  • 2019-01-2224
Published 2019-12-19 by SAE International in United States
For large bore Otto gas engines a high specific power output and therefore high engine load promises a rise in engine efficiency on one hand and on the other hand a reduction of the performance-related investment. However, this can negatively affect the emissions performance, operating limits especially in regards to knocking, and component life. For this reason at the Chair of Internal Combustion Engines (LVK) of the Technical University of Munich (TUM) experiments with a 4.77 l single-cylinder research engine were carried out to investigate the boundary conditions, potentials and downsides of combustion processes with a brake mean effective pressure beyond current series engines and higher than 30 bar. The objective in this investigations was to achieve BMEP > 30 bar with an engine configuration that widely represents the current series-production status. Hence, an unscavenged prechamber spark plug, a series Piston and Valve timing were used. To shift the knocking limit to more fuel-efficient operating points, different intake air temperatures were used. The engine behavior was measured in engine maps with a variation of the…
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