Engine Knock in an SI Engine with Hydrogen Supplementation under Stoichiometric and Lean Conditions

2014 ◽  
Vol 7 (2) ◽  
pp. 595-605 ◽  
Author(s):  
Yu Chen ◽  
Robert Raine
Keyword(s):  
Si Engine ◽  
Engine Knock ◽  
Lean Conditions

Effect of Syngas (H2/CO) on SI Engine Knock under Boosted EGR and Lean Conditions

2017 ◽  
Vol 10 (3) ◽  
pp. 959-969 ◽  
Author(s):  
Taehoon Han ◽  
George Lavoie ◽  
Margaret Wooldridge ◽  
André Boehman
Keyword(s):  
Si Engine ◽  
Engine Knock ◽  
Lean Conditions

scholarly journals Prediction of Cyclic Variability and Knock-Limited Spark Advance (KLSA) in Spark-Ignition (SI) Engine

2018 ◽  
Author(s):  
Zongyu Yue ◽  
K. Dean Edwards ◽  
C. Scott Sluder ◽  
Sibendu Som
Keyword(s):  
Octane Number ◽  
Spark Ignition ◽  
Fuel Properties ◽  
Maximum Efficiency ◽  
Ignition Timing ◽  
Si Engine ◽  
Cfd Simulations ◽  
Chemical Kinetic Model ◽  
Cyclic Variability ◽  
Engine Knock

Engine knock remains one of the major barriers to further improve thermal efficiency of Spark Ignition (SI) engines. Knock can be suppressed by lowering the compression ratio, or retarding the spark ignition timing, however, at an expense of efficiency penalty. SI engine is usually operated at knock-limited spark advance (KLSA) to achieve possibly maximum efficiency with given engine hardware and fuel properties, such as Research Octane Number (RON), Motor Octane Number (MON), and heat of vaporization, etc. Co-optimization of engine design and fuel properties is promising to improve the engine efficiency and predictive CFD models can be used to facilitate this optimization process. However, difficulties exist in predicting KLSA in CFD simulations. First, cyclic variability of SI engine demands that multi-cycle results are required to capture the extreme conditions. Secondly, Mach Courant-Friedrichs-Lewy (CFL) number of 1 is desired to accurately predict the knock intensity (KI), resulting in unaffordable computational cost, especially for multi-cycle simulations. In this study, a new approach to numerically predict KLSA using large Mach CFL number of 50 is proposed. This approach is validated against experimental data for a boosted Direct Injection Spark Ignition (DISI) engine at multiple loads and spark timings. G-equation combustion model coupled with well-mixed chemical kinetic model are used to predict the turbulent flame propagation and end-gas auto-ignition, respectively. Simulations run for 10 consecutive engine cycles at each condition. The results show good agreement between model predictions and experiments in terms of cylinder pressure, combustion phasing and cyclic variation. Engine knock is predicted with early spark ignition timing, indicated by significant pressure wave oscillation and end-gas heat release. Maximum Amplitude of Pressure Oscillation (MAPO) analysis is performed to quantify the KI, and the slope change point in KI extrema is used to indicate the KLSA accurately. Using a smaller Mach CFL number of 5 also results in the same conclusions thus demonstrating that this approach is insensitive to the Mach CFL number. The use of large Mach CFL number allows us to achieve fast turn-around time for multi-cycle engine CFD simulations.

Fuel Composition Effects on Emissions From a Spark-Ignited Engine Operated on Simulated Biogases

1999 ◽  
Vol 123 (1) ◽  
pp. 132-138 ◽  
Author(s):  
K. C. Midkiff ◽  
S. R. Bell ◽  
S. Rathnam ◽  
S. Bhargava
Keyword(s):  
Natural Gas ◽  
Specific Energy Consumption ◽  
Fuel Composition ◽  
Nox Emissions ◽  
Si Engine ◽  
Composition Effects ◽  
Brake Power ◽  
Spark Timing ◽  
Unburned Hydrocarbons ◽  
Lean Conditions

Measurements are reported for a spark-ignited (SI) engine burning natural gas and three simulated biogas fuels (natural gas, CO2, and N2 mixtures). Exhaust concentrations of CO, CO2,O2,NOx, and unburned hydrocarbons, as well as brake power and brake specific energy consumption, were measured. Leaner mixtures, retarded spark timing and diluent addition CO2,N2 yielded reduced NOx emissions. NOx reductions up to 50 percent were achieved at MBT timing through diluent addition. Reduced peak temperatures caused by diluent addition, lean conditions, and retarded spark timing reduced combustion quality slightly, as evidenced by small increases in CO and unburned hydrocarbons emissions.

Lean Limit Extension for High BMEP Gas Engines via Novel Electronic Ignition and Prechamber Plug: Higher Efficiency and Lower NOx in Open Chamber Engines

2011 ◽  
Author(s):  
Domenico Chiera ◽  
David Ahrens ◽  
Nolan Polley ◽  
David Petruska ◽  
Mike Riley ◽  
...  
Keyword(s):  
Natural Gas ◽  
High Performance ◽  
Fuel Efficiency ◽  
Combustion Stability ◽  
Ignition System ◽  
Trade Off ◽  
Spark Plug ◽  
Engine Knock ◽  
Lean Limit ◽  
Lean Conditions

Large bore natural gas engines have the perennial challenge to achieve ever higher efficiency with ever lower NOx emissions, while maintaining stable combustion, avoiding misfire and engine knock. A primary strategτy to achieve these goals is to run leaner and leaner. However, leaner mixtures lead to reduced combustion stability and the operating space between misfire and engine knock shrinks. Leaner operation requires a high performance ignition system. This report will highlight the fundamental challenges related to lean operation and the progress Woodward has made to create a novel high performance prechamber spark plug to achieve good combustion stability in a passive prechamber spark plug under lean conditions. The spark plug in combination with the appropriate ignition system enables faster and more stable combustion under increasingly lean conditions, improving fuel efficiency and emissions. Engine simulation modeling is used to demonstrate the benefits of lean gas mixtures and reduced combustion duration to enhance the NOx versus fuel consumption trade-off for a range of air fuel ratios. With this database available, a design requirements flow-down is performed such that combustion performance requirements can be specified a priori, which if met would ensure the high level engine emissions and performance targets would be met. With combustion requirements in hand, CFD simulations are used to identify the mechanisms by which flame propagation is improved with prechamber spark plugs in general, and by the Lean Quality Plug (WW-LQP) prechamber spark plug under development at Woodward. Experimental validation was carried out to confirm the benefits of lean operation and improvement of combustion stability (COV) on the NOx-efficiency trade-off. Operation with Woodward’s WW-LQP spark plug and IC1100 AC ignition system showed improved fuel efficiency at constant NOx on a high BMEP engine. Additionally, the enhanced stability and low COV of the WW-LQP enables extension of the natural gas lean limit closer to λ = 2.00 for an open chamber engine.

NOx Emissions Reduction of a Natural Gas SI Engine Under Lean Conditions: Comparison of the EGR and RGR Concepts

2006 ◽  
Author(s):  
Olivier Le Corre ◽  
Fre´de´ric Pirotais
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Emissions Reduction ◽  
Nox Emissions ◽  
Si Engine ◽  
Gas Recirculation ◽  
Lean Conditions

In natural gas SI engines under lean conditions, NOx emissions reduction can be realized by injecting an additional mass flow rate to inlet gases. It can be easily done in situ using two techniques: EGR (Exhaust Gas Recirculation) or RGR (Reformed Gas Recirculation) which is an improvement of the usual EGR configuration. Exhaust gases are catalyzed before being reintroduced at the engine inlet. Reformed gases contain carbon monoxide and hydrogen in addition to carbon dioxide, steam and nitrogen dioxide that compose usual recirculated gases. In order to compare EGR and RGR concepts, the study is divided in three stages. Firstly, a “two-zone” thermodynamic model has been developed and validated on a large open chamber SI engine (18L CHP plant engine, fuelled by natural gas and equipped with data acquisition). Both in-cylinder pressure and NOx emissions have been compared between numerical results and experimental data. A good agreement is obtained, the error is less than 3%. Secondly, a widespread model of steam reforming on a Ni/MgOAl2O3 catalyst has been used to compute in particular CO and H2 concentrations. Numerical results lead to a good concordance with experimental data from literature. Finally, SI engine and reformer models have been linked. RGR and EGR configurations have been numerically compared considering the same recirculation mass flow rate. According to the results, RGR is the best way to decrease significantly nitrous oxide emissions, while keeping good engine performance.

Effect of operation under lean conditions on NOx emissions and fuel consumption fueling an SI engine with hydrous ethanol–gasoline blends enhanced with synthesis gas

Energy ◽  
2021 ◽  
pp. 121694
Author(s):  
Ahmed A. Al-Harbi ◽  
Abdullah J. Alabduly ◽  
Abdullah M. Alkhedhair ◽  
Naif B. Alqahtani ◽  
Miqad S. Albishi
Keyword(s):  
Fuel Consumption ◽  
Synthesis Gas ◽  
Nox Emissions ◽  
Si Engine ◽  
Hydrous Ethanol ◽  
Lean Conditions
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