scholarly journals Premixed Combustion of Coconut Oil on Perforated Burner

2013 ◽  
Vol 2 (3) ◽  
pp. 133-139
Author(s):  
I.K.G. Wirawan ◽  
I.N.G. Wardana ◽  
Rudy Soenoko ◽  
Slamet Wahyudi
Keyword(s):  
Equivalence Ratio ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Perforated Plate ◽  
Coconut Oil ◽  
Ambient Air ◽  
Premixed Combustion ◽  
Flame Velocity ◽  
Bunsen Flame ◽  
Rich Mixture

Coconut oil premixed combustion behavior has been studied experimentally on perforated burner with equivalence ratio (φ) varied from very lean until very rich. The results showed that burning of glycerol needs large number of air so that the laminar burning velocity (SL) is the highest at very lean mixture and the flame is in the form of individual Bunsen flame on each of the perforated plate hole. As φ is increased the  SL decreases and the secondary Bunsen flame with open tip occurs from φ =0.54 at the downstream of perforated flame. The perforated flame disappears at φ = 0.66 while the secondary Bunsen flame still exist with SL increases following that of hexadecane flame trend and then extinct when the equivalence ratio reaches one or more. Surrounding ambient air intervention makes SL decreases, shifts lower flammability limit into richer mixture, and performs triple and cellular flames. The glycerol diffusion flame radiation burned fatty acids that perform cellular islands on perforated hole.  Without glycerol, laminar flame velocity becomes higher and more stable as perforated flame at higher φ. At rich mixture the Bunsen flame becomes unstable and performs petal cellular around the cone flame front. Keywords: cellular flame; glycerol; perforated flame;secondary Bunsen flame with open tip; triple flame

Inhibition of Premixed Methane-Air Flames with CF3I

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Caimao Luo ◽  
Bogdan Dlugogorski ◽  
Eric Kennedy ◽  
Behdad Moghtaderi
Keyword(s):  
Sensitivity Analysis ◽  
Pathway Analysis ◽  
Laminar Flame ◽  
Computational Study ◽  
Reaction Pathway ◽  
Burning Velocity ◽  
Flame Velocity ◽  
Promoting Effect ◽  
Elementary Reactions ◽  
Reaction Pathway Analysis

This paper presents a systematic computational study of the inhibition of premixed flames of short chain hydrocarbons with CF3I, focusing on sensitivity analysis of the (normalized) burning velocity and reaction pathway analysis using the "iodine-flux" approach. A comprehensive kinetic mechanism was obtained by combining the GRI, hydrofluorocarbon and CF3I sub-mechanisms, and updating the rates of some of the elementary reactions. Calculations were performed using the PREMIX computer code in the CHEMKIN suite of computer codes. The updated mechanism yielded estimates of the normalized laminar burning velocities which concurs closely with published measurements. The sensitivity analysis resulted in a positive coefficient for CF3I + M ? CF3 + I + M, confirming the promoting effect of CF3I on the laminar flame velocity and is consistent with previous studies. Reaction pathways were drawn for stoichiometric, fuel-lean and fuel-rich flames doped with 1 and 2% of CF3I at atmospheric pressure. The reaction pathway analysis served to identify four major inhibition cycles, denoted as HI ? I ? HI, HI ? I ? I2 ? HI, HI ? I ? CH3I ? HI and HI ? I ? C2H5I ? HI. Furthermore, the paper developed a linear expression linking the normalized rate of heat release with the ratio of laminar burning velocities of mitigated and non-mitigated flames, and verified the efficacy of this expression for flames inhibited with CF3I.

Experimental Study on Laminar Flame Speeds and Markstein Length of Methane-Air Mixtures at Atmospheric Conditions

2014 ◽  
Vol 699 ◽  
pp. 714-719
Author(s):  
Alaeldeen Altag Yousif ◽  
Shaharin Anwar Sulaiman
Keyword(s):  
High Speed ◽  
Equivalence Ratio ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Ambient Pressure ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Atmospheric Conditions ◽  
Laminar Burning Velocity ◽  
Markstein Length

Accurate value of laminar flame speed is an important parameter of combustible mixtures. In this respect, experimental data are very useful for modeling improvement and validating chemical kinetic mechanisms. To achieve this, an experimental characterization on spherically expanding flames propagation of methane-air mixtures were carried out. Tests were conducted in constant volume cylindrical combustion chamber to measure stretched, unstretched laminar flame speed, laminar burning velocity, and flame stretch effect as quantified by the associated Markstein lengths. The mixtures of methane-air were ignited at extensive ranges of lean-to-rich equivalence ratios, under ambient pressure and temperature. This is achieved by high speed schlieren cine-photography for flames observation in the vessel. The results showed that the unstretched laminar burning velocity increased and the peak value of the unstretched laminar burning velocity shifted to the richer mixture side with the increase of equivalence ratio. The flame propagation speed showed different trends at different equivalence ratio for tested mixtures. It was found that the Markstein length was increased with the increase of equivalence ratio.

Turbulent mean reaction rates in the limit of large activation energies

1981 ◽  
Vol 110 ◽  
pp. 411-432 ◽  
Author(s):  
N. Peters ◽  
W. Hocks ◽  
G. Mohiuddin
Keyword(s):  
Reaction Rate ◽  
Laminar Flame ◽  
Mixture Fraction ◽  
Beta Function ◽  
Reaction Rates ◽  
Activation Energies ◽  
Premixed Combustion ◽  
Flame Velocity ◽  
Progress Variable ◽  
The Mean

Closed-form expressions for the turbulent mean reaction rate and its covariance with the temperature are derived for premixed and non-premixed combustion. The limit of large activation energies is exploited for a chemical reaction rate that, by virtue of coupling functions, depends on the mixture fraction and a non-equilibrium progress variable only. The probability density function (p.d.f.) formulation with an assumed shape of the p.d.f. is used; a beta-function distribution is assumed for the progress variable. The mean reaction rate is expressed in terms of the mean and the variance of the temperature and, for non-premixed combustion, of the mixture fraction. The reaction kinetics are represented by the non-dimensional activation energy and the laminar flame velocity. For non-premixed systems the possibility of local extinction by flame stretch is considered.

Laminar Flame Speeds and Strain Sensitivities of Mixtures of H2 With CO, CO2and N2 at Elevated Temperatures

2007 ◽  
Author(s):  
J. Natarajan ◽  
T. Lieuwen ◽  
J. Seitzman
Keyword(s):  
Radiation Effects ◽  
Equivalence Ratio ◽  
Elevated Temperatures ◽  
Laminar Flame ◽  
Flame Speed ◽  
Bunsen Flame ◽  
Clear Trend ◽  
Numerical Predictions ◽  
Fuel Mixtures ◽  
Lean Conditions

Laminar flame speed and strain sensitivities have been measured for mixtures of H2/CO/CO2/N2/O2 with a wall stagnation flame technique at high preheat temperature (700 K) and lean conditions. The measurements are compared with numerical predictions based on two reaction mechanisms: GRI Mech 3.0 and a H2/CO mechanism (Davis et al.). For H2:CO 50:50 fuel mixtures, both models tend to over predict the temperature dependence of the flame speed especially at very lean conditions, which confirms the trend found in an earlier study employing a Bunsen flame technique. The predicted strain sensitivities are in good agreement with the measurements. For 50:50 H2:CO fuel mixtures diluted with 40% CO2, the amount of over prediction by the models is about the same as in the undiluted case, which suggests that radiation effects associated with CO2 addition are not important for this mixture at highly preheated lean condition. For low H2 content (5 to 20%) H2/CO fuel mixtures at 5 atm and fuel lean condition, the predicted unstrained flame speeds are in excellent agreement with the measurements, but the models fail to predicted the strain sensitivity as the amount of H2 increases to 20%. Results are also presented for pure H2 with N2 diluted air (O2:N2 1:9) over a range of equivalence ratios. At lean conditions, the models over predict the measured flame speed by as much as 30%, and the amount of over prediction decreases as the equivalence ratio increases to stoichiometric and rich condition. The measured strain sensitivities are three times higher than the model predictions at lean conditions. More importantly, the predicted strain sensitivities do not change with equivalence ratio for both models, while the measurements reveal a clear trend (decreasing and then increasing) as the fuel-air ratio changes from lean to rich.

Laminar Flame Velocity of Syngas Fuels

2010 ◽  
Author(s):  
Bidhan Dam ◽  
Vishwanath Ardha ◽  
Ahsan Choudhuri
Keyword(s):  
Laminar Flame ◽  
Burning Velocity ◽  
Flame Velocity ◽  
Laminar Burning Velocity ◽  
Velocity Data ◽  
Flame Propagation Velocity ◽  
Exit Velocity ◽  
Flat Flame ◽  
Burner Exit

The paper presents the experimental measurements of the laminar burning velocity of H2-CO mixtures. Hydrogen (H2) and carbon monoxide (CO) are the two primary constituents of syngas fuels. Three burner systems (nozzle, tubular, and flat flame) are used to quantify the effects of burner exit velocity profiles on the determination of laminar flame propagation velocity. The effects to N2 and CO2 diluents have been investigated as well, and it is observed that the effects of N2 and CO2 on the mixture burning velocity are significantly different. Finally, the burning velocity data of various syngas compositions (brown, bituminous, lignite and coke) are presented.

scholarly journals Characteristics of Ammonia/Hydrogen Premixed Combustion in a Novel Linear Engine Generator

Proceedings ◽  
2020 ◽  
Vol 58 (1) ◽  
pp. 2
Author(s):  
Fangyu Zhang ◽  
Gen Chen ◽  
Dawei Wu ◽  
Tie Li ◽  
Zhifei Zhang ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Equivalence Ratio ◽  
Initial Temperature ◽  
Laminar Flame ◽  
Initial Pressure ◽  
Premixed Combustion ◽  
Combustion Mechanism ◽  
Detailed Chemical Kinetics ◽  
Linear Engine ◽  
Premixed Laminar

In order to support the development of a novel linear engine generator (LEG), the characteristics of ammonia/hydrogen premixed combustion are studied by using a detailed chemical kinetics mechanism. The ammonia combustion mechanism is identified among several mechanisms and validated with published experimental data. A parametric analysis is carried out under LEG typical working conditions to study the effects of equivalence ratio (0.80 – 1.60), hydrogen blending ratio (0.0 – 0.6), initial temperature (300 – 700 K) and initial pressure (1 – 20 bar) on premixed laminar flame speed, ignition delay and key flame species concentrations. It is shown that an equivalence ratio of around 1.10 – 1.20 is beneficial to both ammonia flame stability and lower NOx emission. Ignition delay is reduced with the increase in hydrogen blending ratio, initial temperature and initial pressure. At a certain initial temperature and initial pressure, the effects of hydrogen blending ratio can be negligible for over 50% hydrogen in the fuel. Under higher pressure (>10 bar), the initial pressure has a minor influence on the ignition delay reduction. It is also found that the high-pressure high-temperature environment contributes to reducing NO emission considerably in ammonia/hydrogen combustion, which implies the potential of a low NOx LEG fuelled by ammonia/hydrogen.

Prediction of Flame Burning Velocity at Early Flame Development Time With High Exhaust Gas Recirculation and Spark Advance

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
H. Lian ◽  
J. B. Martz ◽  
B. P. Maldonado ◽  
A. G. Stefanopoulou ◽  
K. Zaseck ◽  
...  
Keyword(s):  
Laminar Flame ◽  
Burning Velocity ◽  
Maximum Level ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Flame Velocity ◽  
Flame Development ◽  
Gas Recirculation ◽  
Averaged Model

Diluting spark-ignited (SI) stoichiometric combustion engines with excess residual gas improves thermal efficiency and allows the spark to be advanced toward maximum brake torque (MBT) timing. However, flame propagation rates decrease and misfires can occur at high exhaust gas recirculation (EGR) conditions and advanced spark, limiting the maximum level of charge dilution and its benefits. The misfire limits are often determined for a specific engine from extensive experiments covering a large range of speed, torque, and actuator settings. To extend the benefits of dilute combustion while at the misfire limit, it is essential to define a parameterizable, physics-based model capable of predicting the misfire limits, with cycle to cycle varied flame burning velocity as operating conditions change based on the driver demand. A cycle-averaged model is the first step in this process. The current work describes a model of cycle-averaged laminar flame burning velocity within the early flame development period of 0–3% mass fraction burned. A flame curvature correction method is used to account for both the effect of flame stretch and ignition characteristics, in a variable volume engine system. Comparison of the predicted and the measured flame velocity was performed using a spark plug with fiber optical access. The comparison at a small set of spark and EGR settings at fixed load and speed, shows an agreement within 30% of uncertainty, while 20% uncertainty equals ± one standard deviation over 2000 cycles.

scholarly journals The Role of Magnetic Field Orientation in Vegetable Oil Premixed Combustion

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Dony Perdana ◽  
Lilis Yuliati ◽  
Nurkholis Hamidi ◽  
I. N. G. Wardana
Keyword(s):  
Magnetic Field ◽  
Vegetable Oil ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Stability Limit ◽  
Lewis Number ◽  
Flame Speed ◽  
Premixed Combustion ◽  
Field Orientation ◽  
Magnetic Field Orientation

This study observed the influence of magnetic field orientation on the premixed combustion of vegetable oil. The results show that the magnetic field increased the laminar burning velocity because the spin of electron became more energetic and changes the spin of hydrogen proton from para to ortho. The increase of flame speed became larger on vegetable oil with stronger electric poles. The attraction magnetic field gives the strongest effect against the increase of flame speed and makes flame stability limit wider toward lean equivalence ratio. This is because O2 with the paramagnetic nature is pumped more crossing flame from the south pole (S) to north pole (N) whereas the heat energy carried by H2O from the reaction product with the diamagnetic nature is pumped more crossing flame in the N pole to the S pole. This made the combustion close to Lewis number equal to unity, whereas in the repulsion magnetic poles, S-S, more O2 is pumped into the flame while more heat is pumped out of the flame, and thus, combustion in the flame is leaner and reactions are not optimal. Conversely, at N-N poles, more heat carried by H2O was pumped into the flame while more O2 was pumped out of the flame. As a result, combustion in the flame is richer and the reaction is also not optimal. As a consequence, the velocity of the laminar flame at the repelling poles is lower than that of attracting poles.

scholarly journals The effect of magnetic field variations in a mixture of coconut oil and jatropha on flame stability and characteristics on the premixed combustion

2021 ◽  
pp. 13-22
Author(s):  
Dony Perdana ◽  
Satworo Adiwidodo ◽  
Mochamad Choifin ◽  
Wigo Ardi Winarko
Keyword(s):  
Magnetic Field ◽  
Vegetable Oil ◽  
Laminar Flame ◽  
Coconut Oil ◽  
Flame Speed ◽  
Premixed Combustion ◽  
Flame Stability ◽  
Laminar Flame Speed ◽  
Magnetic Field Variations ◽  
Ratio Range

This study investigates the effect of attracting and repels magnetic fields with the materials of vegetable oil in the form of a mixture of coconut oil and jatropha (B50) against the behavior of stability and characteristics of flame in the process of premixed burning. The fuel for a mixture of vegetable oil of 600 ml was filled into the boiler heated with a gas stove to be evaporated at a temperature of 300 °C and 3 bar pressure was kept constant was mixed with air from the compressor in the burner room. Then a flame was ignited at the end of the nozzle to form a diffusion flame, the flame formed was then given north (N) and south (S). The results showed that the flame speed of the attractive magnetic field was 52.22 cm/sec, the repulsive magnetic field was 50.49 cm/sec while without a magnetic field was 49.79 cm/sec. The increase in the laminar flame speed in the attractive magnetic field is caused by the electron spin becoming more energetic and due to the change in the spin of the hydrogen proton from para to ortho. The attractive magnetic field has the strongest effect on increasing the flame speed. This makes the flame more stable in the equivalency ratio range of 0.75–1.17 compared to without a magnetic field in the same equivalency ratio range. This was so because O2 where it is in nature of paramagnetic was pumped more crossing the flame from south to north poles whereas the heat brought by H2O in nature of diamagnetic was pumped more crossing north to south poles. Whereas on the repel magnetic field, it was hotter when brought by H2O pumped into the flame whereas O2 tended to be pumped going out of the flame. This caused the combustion in the flame was smaller and the reaction was not maximum. As a consequence, the laminar flame speed was more lacking and the reaction was not to the fullest. As a consequence, the laminar flame speed in the repel was fewer than the attract magnetic field

Prediction of Flame Burning Velocity at Early Flame Development Time With High Exhaust Gas Recirculation (EGR) and Spark Advance

2016 ◽  
Author(s):  
H. Lian ◽  
J. B. Martz ◽  
B. P. Maldonado ◽  
A. G. Stefanopoulou ◽  
K. Zaseck ◽  
...  
Keyword(s):  
Laminar Flame ◽  
Burning Velocity ◽  
Maximum Level ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Flame Velocity ◽  
Flame Development ◽  
Gas Recirculation ◽  
Averaged Model

Diluting Spark-Ignited (SI) stoichiometric combustion engines with excess residual gas improves thermal efficiency, and allows spark to be advanced towards Maximum Brake Torque (MBT) timing. However, flame propagation rates decrease and misfires can occur at high Exhaust Gas Recirculation (EGR) conditions and advanced spark, limiting the maximum level of charge dilution and its benefits. The misfire limits are often determined for a specific engine from extensive experiments covering a large range of speed, torque and actuator settings. To extend the benefits of dilute combustion while at the misfire limit, it is essential to define a parameterizable, physics-based model capable of predicting the misfire limits, with cycle to cycle varied flame burning velocity as operating conditions change based on driver demand. A cycle averaged model is the first step in this process. The current work describes a model of cycle averaged laminar flame burning velocity within the early flame development period of 0 to 3 percent mass fraction burned. A flame curvature correction method is used to account for both the effect of flame stretch and ignition characteristics, in a variable volume engine system. Comparison of the predicted and the measured flame velocity was performed using a spark plug with fiber optical access. The comparison at a small set of spark and EGR settings at fixed load and speed, shows an agreement within 30% of uncertainty, while 20% uncertainty equals ± one standard deviation over 2,000 cycles.

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