Flame temperature effect on sp2 bonds on nascent carbon nanoparticles formed in premixed flames (T > 2100 K): A Raman spectroscopy and particle mobility sizing study

2019 ◽  
Vol 37 (1) ◽  
pp. 943-951 ◽  
Author(s):  
Jonathan Bonpua ◽  
Yuniba Yagües ◽  
Aleksandr Aleshin ◽  
Shruthi Dasappa ◽  
Joaquin Camacho
Keyword(s):  
Raman Spectroscopy ◽  
Temperature Effect ◽  
Carbon Nanoparticles ◽  
Flame Temperature ◽  
Premixed Flames ◽  
Particle Mobility

scholarly journals Variable Temperature Synthesis of Tunable Flame-Generated Carbon Nanoparticles

2021 ◽  
Vol 7 (2) ◽  
pp. 44
Author(s):  
Francesca Picca ◽  
Angela Di Pietro ◽  
Mario Commodo ◽  
Patrizia Minutolo ◽  
Andrea D’Anna
Keyword(s):  
Carbon Nanoparticles ◽  
Variable Temperature ◽  
Flame Temperature ◽  
Cost Effective ◽  
Synthesis Process ◽  
Electrical Mobility ◽  
Material Synthesis ◽  
Online Measurements ◽  
Degree Of Graphitization

In this study, flame-formed carbon nanoparticles of different nanostructures have been produced by changing the flame temperature. Raman spectroscopy has been used for the characterization of the carbon nanoparticles, while the particle size has been obtained by online measurements made by electrical mobility analysis. The results show that, in agreement with recent literature data, a large variety of carbon nanoparticles, with a different degree of graphitization, can be produced by changing the flame temperature. This methodology allows for the synthesis of very small carbon nanoparticles with a size of about 3-4 nm and with different graphitic orders. Under the perspective of the material synthesis process, the variable-temperature flame-synthesis of carbon nanoparticles appears as an attractive procedure for a cost-effective and easily scalable production of highly tunable carbon nanoparticles.

Numerical Analysis of Equivalence Ratio Fluctuations in a Partially Premixed Gas Turbine Combustor Using Large Eddy Simulations

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Ping Wang ◽  
Qian Yu ◽  
Prashant Shrotriya ◽  
Mingmin Chen
Keyword(s):  
Reaction Mechanism ◽  
Equivalence Ratio ◽  
Flame Temperature ◽  
Premixed Flames ◽  
Large Eddy Simulations ◽  
Combustion Model ◽  
Inlet Channel ◽  
Large Eddy ◽  
Partially Premixed Flames ◽  
Partially Premixed

In the present work, the fluctuations of equivalence ratio in the PRECCINSTA combustor are investigated via large eddy simulations (LES). Four isothermal flow cases with different combinations of global equivalence ratios (0.7 or 0.83) and grids (1.2 or 1.8 million cells) are simulated to study the mixing process of air with methane, which is injected into the inlet channel through small holes. It is shown that the fluctuations of equivalence ratio are very large, and their ranges are [0.4, 1.3] and [0.3, 1.2] for cases 0.83 and 0.7, respectively. For simulating turbulent partially premixed flames in this burner with the well-known dynamically thickened flame (DTF) combustion model, a suitable multistep reaction mechanism should be chosen aforehand. To do that, laminar premixed flames of 15 different equivalence ratios are calculated using three different methane/air reaction mechanisms: 2S_CH4_BFER, 2sCM2 reduced mechanisms and GRI-Mech 3.0 detailed reaction mechanism. The variations of flame temperature, flame speed and thickness of the laminar flames with the equivalence ratios are compared in detail. It is demonstrated that the applicative equivalence ratio range for the 2S_CH4_BFER mechanism is [0.5, 1.3], which is larger than that of the 2sCM2 mechanism [0.5, 1.2]. Therefore, it is recommended to use the 2S_CH4_BFER scheme to simulate the partially premixed flames in the PRECCINSTA combustion chamber.

Flame Temperature Effect on the Structure of SiC Nanoparticles Grown by Laser Pyrolysis

2004 ◽  
Vol 6 (1) ◽  
pp. 63-70 ◽  
Author(s):  
N. Herlin-Boime ◽  
J. Vicens ◽  
C. Dufour ◽  
F. Ténégal ◽  
C. Reynaud ◽  
...  
Keyword(s):  
Temperature Effect ◽  
Flame Temperature ◽  
Sic Nanoparticles ◽  
Laser Pyrolysis

Time-dependent measurements of flame temperature and the OH radical in the unsteady extinction of non-premixed flames

2005 ◽  
Vol 141 (1-2) ◽  
pp. 186-190 ◽  
Author(s):  
Uen Do Lee ◽  
Kwang Chul Oh ◽  
Hyun Dong Shin ◽  
Ki Ho Lee
Keyword(s):  
Flame Temperature ◽  
Premixed Flames ◽  
Time Dependent ◽  
Oh Radical

scholarly journals Numerical study of the superadiabatic flame temperature phenomenon in hydrocarbon premixed flames

2002 ◽  
Vol 29 (2) ◽  
pp. 1543-1550 ◽  
Author(s):  
Fengshan Liu ◽  
Hongsheng Guo ◽  
Gregory J. Smallwood ◽  
Ömer L. Gülder
Keyword(s):  
Numerical Study ◽  
Flame Temperature ◽  
Premixed Flames

A Numerical Study on the Effect of Water Addition on NO Formation in Counterflow CH4/Air Premixed Flames

2005 ◽  
Author(s):  
Hongsheng Guo ◽  
Stuart W. Neill ◽  
Gregory J. Smallwood
Keyword(s):  
Numerical Study ◽  
Temperature Drop ◽  
Flame Temperature ◽  
Premixed Flames ◽  
Chemical Effect ◽  
Water Addition ◽  
Detailed Chemistry ◽  
Effect Of Water ◽  
No Formation ◽  
The Rich

The effect of water addition on NO formation in counterflow CH4/air premixed flames was investigated by numerical simulation. Detailed chemistry and complex thermal and transport properties were employed. The results show that the addition of water to a flame suppresses the formation of NO primarily due to the flame temperature drop. Among a lean, a stoichiometric and a rich premixed flame, the effectiveness of water addition is most significant for the stoichiometric flame and least for the rich flame, since the dominant NO formation mechanism varies. The addition of water also reduces the formation of NO in a flame because of chemical effect that increases the concentration of OH, while reduces the concentrations of O and H. Compared to the stoichiometric flame, the chemical effect is intensified in the lean and rich flames.

scholarly journals Experimental techniques for the characterization of carbon nanoparticles – a brief overview

2014 ◽  
Vol 5 ◽  
pp. 1760-1766 ◽  
Author(s):  
Wojciech Kempiński ◽  
Szymon Łoś ◽  
Mateusz Kempiński ◽  
Damian Markowski
Keyword(s):  
Electrical Conductivity ◽  
Raman Spectroscopy ◽  
Carbon Nanoparticles ◽  
Carrier Transport ◽  
Structural Changes ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray

The review of four experimental methods: X-ray diffraction, Raman spectroscopy, electron paramagnetic resonance and four-point electrical conductivity measurements is presented to characterize carbon nanoparticles. Two types of carbon nanoparticle systems are discussed: one comprising the powder of individual carbon nanoparticles and the second as a structurally interconnected nanoparticle matrix in the form of a fiber. X-ray diffraction and Raman spectroscopy reveal the atomic structure of the carbon nanoparticles and allow for observation of the changes in the quasi-graphitic ordering induced by ultrasonic irradiation and with the so-called quasi-high pressure effect under adsorption conditions. Structural changes have strong influence on the electronic properties, especially the localization of charge carriers within the nanoparticles, which can be observed with the EPR technique. This in turn can be well-correlated with the four-point electrical conductivity measurements which directly show the character of the charge carrier transport within the examined structures.

Blowout Characteristics of Partially Premixed Flames of Prevaporized Blends of Biofuels and Petroleum Fuels

2017 ◽  
Author(s):  
Tonci Maleta ◽  
Ramkumar N. Parthasarathy ◽  
Subramanya R. Gollahalli
Keyword(s):  
Laminar Flame ◽  
Flame Temperature ◽  
Premixed Flames ◽  
Temperature Profiles ◽  
Flame Velocity ◽  
Gas Phase Reactions ◽  
Partially Premixed Flames ◽  
Inner Diameter ◽  
Partially Premixed ◽  
Petroleum Fuels

The laminar partially premixed flames of prevaporized Jet-A, canola methyl ester (CME) and blend flames of Jet-A and CME were studied over a range of equivalence ratios of 0.6–0.8 with and without heated coflow. Measurements of blowout velocities and flame temperature profiles were made. The injector was designed to produce a uniform inner flow and had an inner diameter of 12.7 mm. The flames were laminar and blue in color (dominated by homogeneous gas-phase reactions). The temperature profiles in all the flames were similar, with a peak temperature of 1680 K. The blowout velocity increased with equivalence ratio for all the flames; the blowout velocity of pure CME flames was higher than that of pure Jet-A flames with no coflow present. The blowout velocity of the blend flames ranged around the values for the pure fuel flames. A Damkohler number (based on the velocity gradient at the jet boundary and chemical reaction time scale estimated from laminar flame velocity) of unity characterizes the blowout velocity. As the coflow velocity was increased, the blowout velocity was increased, and the differences between the values for the various flames became smaller.

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