scholarly journals Combustion of Hydrogen Enriched Methane and Biogases Containing Hydrogen in a Controlled Auto-Ignition Engine

2018 ◽  
Vol 8 (12) ◽  
pp. 2667
Author(s):  
Antonio Mariani ◽  
Andrea Unich ◽  
Mario Minale
Keyword(s):  
Equivalence Ratio ◽  
Numerical Study ◽  
Chemical Reactivity ◽  
Combustion Process ◽  
Pollutant Emissions ◽  
Ignition Process ◽  
Effective Pressure ◽  
Indicated Mean Effective Pressure ◽  
Auto Ignition ◽  
Combustion Of Hydrogen

The paper describes a numerical study of the combustion of hydrogen enriched methane and biogases containing hydrogen in a Controlled Auto Ignition engine (CAI). A single cylinder CAI engine is modelled with Chemkin to predict engine performance, comparing the fuels in terms of indicated mean effective pressure, engine efficiency, and pollutant emissions. The effects of hydrogen and carbon dioxide on the combustion process are evaluated using the GRI-Mech 3.0 detailed radical chain reactions mechanism. A parametric study, performed by varying the temperature at the start of compression and the equivalence ratio, allows evaluating the temperature requirements for all fuels; moreover, the effect of hydrogen enrichment on the auto-ignition process is investigated. The results show that, at constant initial temperature, hydrogen promotes the ignition, which then occurs earlier, as a consequence of higher chemical reactivity. At a fixed indicated mean effective pressure, hydrogen presence shifts the operating range towards lower initial gas temperature and lower equivalence ratio and reduces NOx emissions. Such reduction, somewhat counter-intuitive if compared with similar studies on spark-ignition engines, is the result of operating the engine at lower initial gas temperatures.

scholarly journals Influence of Compression Ratio on Flywheel Dimension for a Naturally Aspirated Spark Ignition Engine: A Numerical Study

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Aan Yudianto ◽  
Peixuan Li
Keyword(s):  
Compression Ratio ◽  
Numerical Study ◽  
Engine Performance ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Effective Pressure ◽  
Si Engine ◽  
Compression Stroke ◽  
Indicated Mean Effective Pressure ◽  
Proper Design

The proper design of the flywheel undeniably determines in tuning the engine to confirm the better output engine performance. The aim of this study is to mathematically investigate the effect of various values of the compression ratio on some essential parameters to determine the appropriate value for the flywheel dimension. A numerical calculation approach was proposed to eventually determine the dimension of the engine flywheel on a five-cylinder four-stroke Spark Ignition (SI) engine. The various compression ratios of 8.5, 9, 9.5, 10, 10.5, and 11 were selected to perform the calculations. The effects of compression ratio on effective pressure, indicated mean effective pressure (IMEP), dynamic irregularity value of the crankshaft, and the diameter of the flywheel was clearly investigated. The study found that 2.5 increment value of the compression ratio significantly increases the effective pressure of about 41.53% on the starting of the expansion stroke. While at the end of the compression stroke, the rise of effective pressure is about 76.67%, and the changes in dynamic irregularity merely increase by about 1.79%. The same trend applies to the flywheel diameter and width, which increases 2.08% for both.

scholarly journals Potential of hydrogen addition to natural gas or ammonia as a solution towards low- or zero-carbon fuel for the supply of a small turbocharged SI engine

2021 ◽  
Vol 312 ◽  
pp. 07022
Author(s):  
Alfredo Lanotte ◽  
Vincenzo De Bellis ◽  
Enrica Malfi
Keyword(s):  
Alternative Fuels ◽  
Laminar Flame ◽  
Combustion Engine ◽  
Numerical Study ◽  
Combustion Process ◽  
Pollutant Emissions ◽  
Si Engine ◽  
Hydrogen Addition ◽  
Emission Regulations ◽  
Zero Carbon

Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those fuels, on one hand, allow to drastically reduce CO2 emissions, helping to comply with the increasingly stringent emission regulations, and, on the other hand, could lead to possible advantages in performances if blended with conventional fuels. In this regard, this work focuses on the 1D numerical study of an internal combustion engine supplied with different fuels: pure gasoline, and blends of methane-hydrogen and ammonia-hydrogen. The analyses are carried out with reference to a downsized turbocharged two-cylinder engine working in an operating point representative of engine operations along WLTC, namely 1800 rpm and 9.4 bar of BMEP. To evaluate the potential of methane-hydrogen and ammonia-hydrogen blends, a parametric study is performed. The varied parameters are air/fuel proportions (from 1 up to 2) and the hydrogen fraction over the total fuel. Hydrogen volume percentages up to 60% are considered both in the case of methane-hydrogen and ammonia-hydrogen blends. Model predictive capabilities are enhanced through a refined treatment of the laminar flame speed and chemistry of the end gas to improve the description of the combustion process and knock phenomenon, respectively. After the model validation under pure gasoline supply, numerical analyses allowed to estimate the benefits and drawbacks of considered alternative fuels in terms of efficiency, carbon monoxide, and pollutant emissions.

An investigation for reducing combustion instability under cold-start condition of a direct injection gasoline engine

2018 ◽  
Vol 20 (4) ◽  
pp. 470-479 ◽  
Author(s):  
Koshiro Kimura ◽  
Sachio Mori ◽  
Masato Kawauchi ◽  
Rio Shimizu
Keyword(s):  
Flame Propagation ◽  
Equivalence Ratio ◽  
Direct Injection ◽  
Cold Start ◽  
Spark Ignition Engine ◽  
Injection Timing ◽  
Effective Pressure ◽  
Indicated Mean Effective Pressure ◽  
The Mean ◽  
Initial Flame

In order to meet recent stringent emission regulations, the exhaust catalyst should be heated as early as possible to activate the purifying reactions. In a direct injection spark-ignition engine, a combination of late fuel injection during the compression stroke and late ignition in the expansion stroke is a common strategy to quickly raise exhaust gas temperature for subsequent rapid activation of exhaust catalysts. However, this approach under cold start-up of an engine often results in incomplete and unstable combustion. In this study, to explore the conditions of stable ignition and combustion, the effect of injection timing on indicated mean effective pressure and early combustion duration (MBD0.5) are first investigated by an analysis of the pressure indicator diagram. As this analysis shows a strong correlation between indicated mean effective pressure and MBD0.5, the mechanism of initial flame propagation is investigated intensively using optical diagnostics. Namely, mean equivalence ratio of mixtures in the propagating flame front is measured by focusing on the ratio of C2* to CH* emission intensities. The flow velocity and turbulence intensity around the spark electrode are measured by the back-scattering laser Doppler anemometry. Two major conclusions are derived from this study: First, when the injection timing is retarded, the mean equivalence ratio increases as the time for the injected fuel to travel and diffuse is shortened. The most preferable mean equivalence ratio for fast initial combustion is found to lie in a range from 1.2 to 1.4. Second, when the second injection timing is retarded further, the mean equivalence ratio increases exceeding 1.4, and this results in slower and more fluctuated initial flame propagation. But, if the turbulent intensity is increased by means of the spray induced air motion, the slowed initial combustion can be recovered.

Design of a Model Based Controller for Regulation of Auto-Ignition

2005 ◽  
Author(s):  
William de Ojeda
Keyword(s):  
Ignition Temperature ◽  
Combustion Process ◽  
Flow Characteristics ◽  
Ignition Process ◽  
Intake Valve ◽  
Model Predictive Controller ◽  
Auto Ignition ◽  
Charge Mixture ◽  
Predictive Controller ◽  
Noise Factors

The present paper considers a model predictive controller to sustain a combustion system that relies in the auto-ignition of a fuel/air mixture. The auto-ignition process relies in elevating the fuel/air mixture to the ignition temperature to initiate the combustion process. The homogeneity or heterogeneous characteristics of the mixture have a strong influence on the process as well as the fuel composition, Diesel or gasoline, and charge mixture temperature. The auto-ignition process is examined in a compression ignition (CI) engine platform, with Diesel fuel premixed early in the compression cycle with the charge air. The variations in the temperature of the charge air in each cylinder encountered due to variations in cooling in the cylinder head or unsymmetrical flow characteristics are compensated using a model predictive controller to manipulate the intake valve closing timing (IVC). IVC regulates the effective compression ratio and the timing with respect to the cylinder’s top dead center position when the charge temperature reaches the auto-ignition temperature. Simultaneously, the controller manipulates the fuel mass delivered to the cylinder to adjust torque to the desired level. The paper shows empirical correlations between the intake valve closing and fueling to auto-ignition timing and torque that serve to solve the predictive model when subject to various noise factors.

scholarly journals Indicated Mean Effective Pressure Oscillations in a Natural Gas Combustion Engine

2009 ◽  
Vol 64 (5-6) ◽  
pp. 393-398 ◽  
Author(s):  
Grzegorz Litak ◽  
Michał Gęca ◽  
Bao-Feng Yao ◽  
Guo-Xiu Li
Keyword(s):  
Natural Gas ◽  
Combustion Engine ◽  
Combustion Process ◽  
Spark Ignition Engine ◽  
Effective Pressure ◽  
Gas Combustion ◽  
Indicated Mean Effective Pressure ◽  
Natural Gas Combustion ◽  
Measured Pressure ◽  
Lean Conditions

Fluctuations in a combustion process of natural gas in the internal spark ignition engine have been investigated. We measured pressure of the cyclic combustion and expressed its cyclic oscillations in terms of indicated mean effective pressure per cycle. By applying the statistical and multifractal analysis to the corresponding time series we show the considerable changes in engine dynamics for a different equivalence ratio decreases from 0.781 to very lean conditions.

scholarly journals Numerical Study of Hydrogen Auto-Ignition Process in an Isotropic and Anisotropic Turbulent Field

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1869
Author(s):  
Agnieszka Wawrzak ◽  
Artur Tyliszczak
Keyword(s):  
Ignition Delay ◽  
Numerical Study ◽  
Maximum Temperature ◽  
Combustion Model ◽  
Ignition Process ◽  
Length Scales ◽  
Flame Kernel ◽  
Turbulent Field ◽  
Auto Ignition ◽  
Turbulence Length

The physical mechanisms underlying the dynamics of the flame kernel in stationary isotropic and anisotropic turbulent field are studied using large eddy simulations (LES) combined with a pdf approach method for the combustion model closure. Special attention is given to the ignition scenario, ignition delay, size and shape of the flame kernel among different turbulent regimes. Different stages of ignition are analysed for various levels of the initial velocity fluctuations and turbulence length scales. Impact of these parameters is found small for the ignition delay time but turns out to be significant during the flame kernel propagation phase and persists up to the stabilisation stage. In general, it is found that in the isotropic conditions, the flame growth and the rise of the maximum temperature in the domain are more dependent on the initial fluctuations level and the length scales. In the anisotropic regimes, these parameters have a substantial influence on the flame only during the initial phase of its development.

The influence of intermediate species on the combustion process of n-dodecane flame

2019 ◽  
Vol 234 (2-3) ◽  
pp. 334-348
Author(s):  
Wanhui Zhao ◽  
Lei Zhou ◽  
Jiayue Qi ◽  
Haiqiao Wei
Keyword(s):  
Oxygen Concentration ◽  
Ignition Delay ◽  
Combustion Process ◽  
Great Influence ◽  
Engine Performance ◽  
Pollutant Emissions ◽  
Ignition Process ◽  
Gas Temperature ◽  
Initial Oxygen ◽  
Main Influence

Split-injection strategy is of great potential to reduce the pollutant emissions without deterioration of engine performance. The combustion of the previously injected fuel has great influence on the ignition of the subsequent second injection. In this study, the main influence of species formed in the first injection on the ignition of the second injection is analysed in detail. Different species are added into the fuel/air mixture to study the influence of the species formed in the first injection on the combustion process of the second injection. Results show that the influence of species addition on the ignition delay is dependent on the initial temperature and oxygen concentration. The presence of acetylene (C2H2) and methane (CH4) prolongs the ignition delay regardless of initial temperatures or oxygen concentrations. However, ethylene (C2H4), hydrogen peroxide (H2O2), hydrogen (H2) and formaldehyde (CH2O) shorten the ignition delay at high temperatures. The temperature increase ahead of the second spray plays a more important role in promoting the overall ignition process regardless of the initial oxygen concentration. Moreover, the effect of species addition on the first- and second-stage ignition processes is also analysed in detail. Different from the results with other species addition, the presence of H2O2 and CH2O in the initial gas leads to the monotonical decrease with the increase in the initial gas temperature, T0.

scholarly journals Effects of CNG quantity on combustion characteristics and emissions of a dual fuelled automotive diesel engine

2020 ◽  
Vol 180 ◽  
pp. 01008
Author(s):  
Silviu Rotaru ◽  
Constantin Pana ◽  
Nicolae Negurescu ◽  
Alexandru Cernat ◽  
Dinu Fuiorescu ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Natural Gas ◽  
Combustion Process ◽  
Operating Regime ◽  
Intake Manifold ◽  
Maximum Pressure ◽  
Effective Pressure ◽  
Compressed Natural Gas ◽  
Positive Effects ◽  
Indicated Mean Effective Pressure

The paper reveals some experimental aspects of compressed natural gas (CNG) use in dual fuel mode at an automotive diesel engine. Brake specific energetic consumption, incylinder pressure, emissions and variability of indicated mean effective pressure are analysed at operating regime of 2000 rpm and 40% load. Using CNG as an alternative fuel reduces brake specific energetic consumption by 50%, the CO2 emission by 10% and sets the in-cylinder maximum pressure 13 bar higher comparative to diesel fuel fuelling. The smoke and hydrocarbons emissions and the variability of indicated mean effective pressure are affected by the injection of compressed natural gas into intake manifold: HC emission grows 24 times, the smoke number and the coefficient of variability of IMEP double their values. The use of compressed natural gas at an automotive diesel engine improves its energetic performances and combustion process, having positive effects on CO2 emission and fuel consumption.

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