Investigation of the Influence of Compression Ratio, Intake Air Temperature and Swirl in Intake passage on Random Cyclic Pressure Variations in Spark-Ignition Engines

2007 ◽  
Author(s):  
T.K. Chandrashekar ◽  
R.Harish kumar ◽  
A.J. Antony
Keyword(s):  
Air Temperature ◽  
Compression Ratio ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Cyclic Pressure

Quantification of knock benefits from reformate and cooled exhaust gas recirculation using a Livengood–Wu approach with detailed chemical kinetics

2016 ◽  
Vol 18 (7) ◽  
pp. 717-731 ◽  
Author(s):  
David K Marsh ◽  
Alexander K Voice
Keyword(s):  
Carbon Monoxide ◽  
Compression Ratio ◽  
Exhaust Gas Recirculation ◽  
Spark Ignition ◽  
Mitigation Strategies ◽  
Exhaust Gas ◽  
Spark Ignition Engines ◽  
Volume Percent ◽  
Hydroxy Radicals ◽  
Gas Recirculation

In this work, a simple methodology was implemented to predict the onset of knock in spark-ignition engines and quantify the benefits of two practical knock mitigation strategies: cooled exhaust gas recirculation and syngas blending. Based on the results of this study, both cooled exhaust gas recirculation and the presence of syngas constituents in the end-gas substantially improved the knock-limited compression ratio of the engine. At constant load, 25% exhaust gas recirculation increased the knock-limited compression ratio from 9.0 to 10.8:1 (0.07 compression ratio per 1% exhaust gas recirculation) due to lower end-gas temperature and reactant (fuel and oxygen) concentrations. At exhaust gas recirculation rates above 43%, higher intake temperature outweighed the benefits of lower end-gas reactant concentration. At constant intake temperature, cooled exhaust gas recirculation was significantly more effective at all exhaust gas recirculation rates (0.10 compression ratio per 1% exhaust gas recirculation), and no diminishing returns or optimum was observed. Both hydrogen and carbon monoxide were also predicted to improve knock by reducing end-gas reactivity, likely through the conversion of high-reactivity hydroxy-radicals to less reactive peroxy-radicals. Hydrogen increased the knock-limited compression ratio by 1.1 per volume percent added at constant energy content. Carbon monoxide was less effective, increasing the knock-limited compression ratio by 0.38 per volume percent added. Combining 25% cooled exhaust gas recirculation with reformate produced from rich combustion at an equivalence ratio of 1.3 resulted in a predicted increase in the knock-limited compression ratio of 3.5, which agreed well with the published experimental engine data. The results show the extent to which syngas blending and cooled exhaust gas recirculation each contribute separately to knock mitigation and demonstrate that both can be effective knock mitigation strategies. Together, these solutions have the potential to increase the compression ratio and efficiency of spark-ignition engines.

scholarly journals Enabling high compression ratio in boosted spark ignition engines: Thermodynamic trajectory and fuel chemistry effects on knock

2020 ◽  
Vol 222 ◽  
pp. 446-459
Author(s):  
Flavio Dal Forno Chuahy ◽  
Derek Splitter ◽  
Vicente Boronat ◽  
Scott W. Wagnon
Keyword(s):  
Compression Ratio ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
High Compression Ratio ◽  
High Compression

STOCHASTIC MODELLING AND ESTIMATION FOR CYCLIC PRESSURE VARIATIONS IN SPARK IGNITION ENGINES

2001 ◽  
Vol 15 (2) ◽  
pp. 419-438 ◽  
Author(s):  
J.B. ROBERTS ◽  
J.C. PEYTON JONES ◽  
K.J. LANDSBOROUGH
Keyword(s):  
Stochastic Modelling ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Cyclic Pressure

scholarly journals The Operating Features of a Stoichiometric, Ammonia and Gasoline Dual Fueled Spark Ignition Engine

2006 ◽  
Author(s):  
Shawn M. Grannell ◽  
Dennis N. Assanis ◽  
Stanislav V. Bohac ◽  
Donald E. Gillespie
Keyword(s):  
Compression Ratio ◽  
Thermal Efficiency ◽  
Maximum Load ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Gaseous Ammonia ◽  
Spark Ignition Engines ◽  
Stoichiometric Mixture ◽  
Brake Thermal Efficiency ◽  
Practical Operation

An overall stoichiometric mixture of air, gaseous ammonia and gasoline was metered into a single cylinder, variable compression ratio, supercharged CFR engine at varying ratios of gasoline to ammonia. The engine was operated such that the combustion was knock-free with minimal roughness for all loads ranging from idle up to a maximum load in the supercharge regime. For a given load, speed, and compression ratio there was a range of ratios of gasoline to ammonia for which knock-free, smooth firing was obtained. This range was investigated at its roughness limit and also at its knock limit. If too much ammonia was used, then the engine fired with an excessive roughness. If too much gasoline was used, then knock-free combustion could not be obtained while the maximum brake torque spark advance was maintained. Stoichiometric operation on gasoline alone was also investigated, for comparison. It was found that a significant fraction of the gasoline used in spark ignition engines could be replaced with ammonia. Operation on mostly gasoline was required near idle. However, mostly ammonia could be used at high load. Operation on ammonia alone was possible at some of the supercharged load points. Generally, the use of ammonia or ammonia with gasoline allowed knock-free operation at higher compression ratios and higher loads than could be obtained with the use of gasoline alone. The use of ammonia/gasoline allowed practical operation at a compression ratio of 12:1 whereas the limit for gasoline alone was 9:1. When running on ammonia/gasoline the engine could be operated at brake mean effective pressures that were more than 50% higher than those achieved with the use of gasoline alone. The maximum brake thermal efficiency achieved with the use of ammonia/gasoline was 32.0% at 10:1 compression ratio and BMEP = 1025 kPa. The maximum brake thermal efficiency possible for gasoline was 24.6% at 9:1 and BMEP = 570 kPa.

The Fuel Mix Limits and Efficiency of a Stoichiometric, Ammonia, and Gasoline Dual Fueled Spark Ignition Engine

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Shawn M. Grannell ◽  
Dennis N. Assanis ◽  
Stanislav V. Bohac ◽  
Donald E. Gillespie
Keyword(s):  
Compression Ratio ◽  
Maximum Load ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Significant Fraction ◽  
Gaseous Ammonia ◽  
Spark Ignition Engines ◽  
Stoichiometric Mixture ◽  
Brake Torque ◽  
Spark Timing

An overall stoichiometric mixture of air, gaseous ammonia, and gasoline was metered into a single cylinder, variable compression ratio, supercharged cooperative fuel research (CFR) engine at varying ratios of gasoline to ammonia. The engine was operated such that the combustion was knock-free with minimal roughness for all loads ranging from idle up to a maximum load in the supercharge regime. For a given load, speed, and compression ratio, there was a range of ratios of gasoline to ammonia for which knock-free, smooth firing was obtained. This range was investigated at its rough limit and also at its maximum brake torque (MBT) knock limit. If too much ammonia was used, then the engine fired with an excessive roughness. If too much gasoline was used, then knock-free combustion could not be obtained while the maximum brake torque spark timing was maintained. Stoichiometric operation on gasoline alone is also presented, for comparison. It was found that a significant fraction of the gasoline used in spark ignition engines could be replaced with ammonia. Operation on about 100% gasoline was required at idle. However, a fuel mix comprising 70% ammonia∕30% gasoline on an energy basis could be used at normally aspirated, wide open throttle. Even greater ammonia to gasoline ratios were permitted for supercharged operation. The use of ammonia with gasoline allowed knock-free operation with MBT spark timing at higher compression ratios and higher loads than could be obtained with the use of gasoline alone.

Knock Rating of Gaseous Fuels

2003 ◽  
Vol 125 (2) ◽  
pp. 500-504 ◽  
Author(s):  
A. A. Attar ◽  
G. A. Karim
Keyword(s):  
Binary Mixtures ◽  
Compression Ratio ◽  
Equivalence Ratio ◽  
Spark Ignition ◽  
The Other ◽  
Mixture Composition ◽  
Spark Ignition Engines ◽  
Gaseous Fuels ◽  
Spark Timing ◽  
Methane Number

The knock tendency in spark ignition engines of binary mixtures of hydrogen, ethane, propane and n-butane is examined in a CFR engine for a range of mixture composition, compression ratio, spark timing, and equivalence ratio. It is shown that changes in the knock characteristics of binary mixtures of hydrogen with methane are sufficiently different from those of the binary mixtures of the other gaseous fuels with methane that renders the use of the methane number of limited utility. However, binary mixtures of n-butane with methane may offer a better alternative. Small changes in the concentration of butane produce almost linearly significant changes in both the values of the knock limited compression ratio for fixed spark timing and the knock limited spark timing for a fixed compression ratio.

Evaluation of compression ratio and blow-by rates for spark ignition engines based on in-cylinder pressure trace analysis

2018 ◽  
Vol 162 ◽  
pp. 98-108 ◽  
Author(s):  
Adrian Irimescu ◽  
Silvana Di Iorio ◽  
Simona Silvia Merola ◽  
Paolo Sementa ◽  
Bianca Maria Vaglieco
Keyword(s):  
Compression Ratio ◽  
Trace Analysis ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Cylinder Pressure ◽  
Pressure Trace
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