scholarly journals Numerical Simulation of the Influence of CO2 on the Combustion Characteristics and NOX of Biogas

2022 ◽  
Vol 9 ◽  
Author(s):  
Jinshuang Ma ◽  
Chuanjia Qi ◽  
Siyi Luo ◽  
Zongliang Zuo
Keyword(s):  
Flame Propagation ◽  
Chemical Equilibrium ◽  
Combustion Temperature ◽  
Molar Fraction ◽  
Volume Ratio ◽  
Calorific Value ◽  
Propagation Speed ◽  
Inert Gases ◽  
Flame Combustion ◽  
Flame Propagation Speed

The existence of inert gases such as N2 and CO2 in biogas will reduce the proportion of combustible components in syngas and affect the combustion and NOX formation characteristics. In this study, ANSYS CHEMKIN-PRO software combined with GRI-MECH 3.0 mechanism was used to numerically simulate the effects of different CO2 concentrations (CO2 volume ratio in biogas is 0–41.6%) on flame combustion temperature, flame propagation speed and nitrogen oxide formation of complex biogas with low calorific value. The results showed that when the combustion reaches the chemical equilibrium, the flame combustion temperature and flame propagation speed decrease with the increase of CO2 concentration, and the flame propagation speed decreases even more slowly. Meanwhile, the molar fraction of NO at chemical equilibrium decreases with the increase of CO2 concentration and the decrease is decreasing, which indicates that the effect of CO2 concentration in biogas on NO is simpler. While the molar fraction of NO2 does not change regularly with the change of CO2 concentration, the effect of CO2 concentration in biogas on NO2 is complicated. The highest molar fraction of NO2 was found at chemical equilibrium when the CO2 concentration was 33.6%, when the target was a typical low calorific value biogas.

Ignition Dynamics in an Annular Combustor With Gyratory Flow Motion

2018 ◽  
Author(s):  
Chenran Ye ◽  
Gaofeng Wang ◽  
Yuanqi Fang ◽  
Chengbiao Ma ◽  
Liang Zhong ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Velocity Component ◽  
Thermal Power ◽  
Propagation Speed ◽  
Circumferential Velocity ◽  
Bulk Velocity ◽  
Ignition Process ◽  
Flow Motion ◽  
Annular Combustor ◽  
Flame Propagation Speed

In concepts of integrated design of combustor and turbine, an annular combustor model is developed and featured with multiple oblique-injecting swirling injectors to introduce gyratory flow motion in the combustion chamber. The ignition process is experimentally investigated to study the effects of introducing circumferential velocity component Uc to the light-round sequence. Experiments are carried out with premixed propane/air mixture in ambient conditions. The light-round sequence is recorded by a high-speed camera, which provides detailed flame azimuthal positions during the sequence and gives access to the light-round time τ and the circumferential flame propagation speed Sc. The results have also been compared with that obtained from a straight-injecting annular combustor. The effects of bulk velocity Ub, thermal power P and equivalence ratio Φ are also explored. Due to the gyratory flow motion induced by oblique injection, the flame fronts only propagate along the direction of circumferential flow. Both of the circumferential flame propagation speed increase with increasing bulk velocity in two injection types. It seems mainly to depend on bulk velocity, regardless of Φ, in oblique-injecting combustor when compared with the straight one. It indicates that the circumferential velocity component would play a dominant role in light-round sequence when it is sufficient higher than the displacement flame speed.

A Comparative Study of Methane Combustion Characteristics with Different Additions in an Optical SI Engine

2021 ◽  
Author(s):  
Lin Chen ◽  
Xiao Zhang ◽  
Ren Zhang ◽  
Wanhui Zhao
Keyword(s):  
Natural Gas ◽  
Flame Propagation ◽  
Power Output ◽  
High Speed ◽  
Propagation Speed ◽  
Pressure Oscillation ◽  
Methane Combustion ◽  
Natural Gas Engines ◽  
Auto Ignition ◽  
Flame Propagation Speed

Abstract Natural gas is a promising fuel for IC engines with minimal modification, whereas its low power output and slow flame propagation speed remain a challenge for automobile manufacturers. To find a method of improving the natural gas engines, methane combustion with different additions was comparatively studied. High-speed direct photography and simultaneous pressure were performed to capture detailed combustion evolutions. First, the results of pure methane combustion confirm its good anti-knock property, and no pressure oscillation occurs even there is an end-gas auto-ignition, indicating that high compression ratio and high boosting are effective ways to improve the performance of natural gas engines. Second, adding heavy hydrocarbons can greatly improve engines' power output, but engine knock should be considered if low anti-knock fuel was used. Third, as a carbon-free and gaseous fuel, hydrogen addition can not only increase methane flame propagation speed but reduce cyclic variations. However, a proper fraction is needed under different load conditions. Last, oxygen-enriched combustion is an effective way to promote methane combustion. The heat release becomes faster and more concentrated, specifically, the flame propagation speed can be increased by more than 2 times under 27% oxygen concentration condition. The current study shall give insights into improving natural gas engines' performance.

scholarly journals Investigation of Pressure Rise and Flame Acceleration Characteristics in a Single Channel of Wave Rotor Combustor with Spoilers

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Jianzhong Li ◽  
Kaichen Zhang ◽  
Wei Li ◽  
Li Yuan
Keyword(s):  
Flame Propagation ◽  
Single Channel ◽  
Pressure Rise ◽  
Propagation Speed ◽  
Blockage Ratio ◽  
Wave Rotor ◽  
Flame Acceleration ◽  
Channel Wave ◽  
Experimental Rig ◽  
Flame Propagation Speed

A simplified single channel wave rotor combustor (WRC) experimental rig was established, in which the spoilers with different blockage ratios (BR) could be conveniently installed and disassembled. The spoilers were firstly used for WRC to improve the pressure rise. The effects of different blockage ratios on the pressure rise and flame acceleration characteristics in a single channel of the WRC were investigated. The addition of spoilers could remarkably improve the pressure rise and flame propagation speed in a single channel of the WRC. While the blockage ratio of the spoiler increases, both pressure rise and mean flame propagation speed are improved. When the spoilers with a blockage ratio of 38.91% are used, the peak pressure increases by 200% compared to that of WRC without the spoilers. When the spoilers of different blockage ratios (23.35%, 31.13%, and 38.91%) are used, it is found that the flame propagation speed is significantly improved with the increasing of the blockage ratio. Specifically, the maximum flame propagation speed reaches 55 m/s, and the maximum mean flame propagation speed is 36.95 m/s. Furthermore, combustion becomes more intense, and the flame is brighter around the spoiler.

Effect of additional diluents on flame propagation speed and markstein length in outwardly propagating premixed methane/ethylene–air flames

2018 ◽  
Vol 32 (11) ◽  
pp. 5501-5509 ◽  
Author(s):  
Hee June Kim ◽  
Kyuho Van ◽  
Kee Man Lee ◽  
Dae Keun Lee ◽  
Young Tae Guahk ◽  
...  
Keyword(s):  
Flame Propagation ◽  
Propagation Speed ◽  
Markstein Length ◽  
Flame Propagation Speed

Effects of electric field intensity and distribution on flame propagation speed of CH4/O2/N2 flames

Fuel ◽  
2015 ◽  
Vol 158 ◽  
pp. 807-815 ◽  
Author(s):  
Hao Duan ◽  
Xiaomin Wu ◽  
Tianqi Sun ◽  
Bing Liu ◽  
Jianfeng Fang ◽  
...  
Keyword(s):  
Electric Field ◽  
Flame Propagation ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Propagation Speed ◽  
Flame Propagation Speed

Cyclic flame propagation in premixed combustion

2013 ◽  
Vol 735 ◽  
pp. 176-202 ◽  
Author(s):  
Philipp A. Boettcher ◽  
Shyam K. Menon ◽  
Brian L. Ventura ◽  
Guillaume Blanquart ◽  
Joseph E. Shepherd
Keyword(s):  
Flame Propagation ◽  
Propagation Speed ◽  
Power Input ◽  
Combustion Products ◽  
Flame Speed ◽  
Field Analysis ◽  
Gravitational Acceleration ◽  
Inflow Velocity ◽  
Hot Surface ◽  
Flame Propagation Speed

AbstractIn experiments of hot surface ignition and subsequent flame propagation, a puffing flame instability is observed in mixtures that are stagnant and premixed prior to ignition. By varying the size of the hot surface, power input, and combustion vessel volume, it was determined that the instability is a function of the interaction of the flame, with the fluid flow induced by the combustion products rather than the initial plume established by the hot surface. Pressure ranges from 25 to 100 kPa and mixtures of n-hexane/air with equivalence ratios between $\phi = 0. 58$ and 3.0 at room temperature were investigated. Equivalence ratios between $\phi = 2. 15$ and 2.5 exhibited multiple flame and equivalence ratios above $\phi = 2. 5$ resulted in puffing flames at atmospheric pressure. The phenomenon is accurately reproduced in numerical simulations and a detailed flow field analysis revealed competition between the inflow velocity at the base of the flame and the flame propagation speed. The increasing inflow velocity, which exceeds the flame propagation speed, is ultimately responsible for creating a puff. The puff is then accelerated upward, allowing for the creation of the subsequent instabilities. The frequency of the puff is proportional to the gravitational acceleration and inversely proportional to the flame speed. A scaling relationship describes the dependence of the frequency on gravitational acceleration, hot surface diameter, and flame speed. This relation shows good agreement for rich n-hexane/air and lean hydrogen/air flames, as well as lean hexane/hydrogen/air mixtures.

An Experimental Investigation on the Combustion Process of a Simulated Turbocharged Spark Ignition Natural Gas Engine Operated on Stoichiometric Mixture

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Hailin Li ◽  
Timothy Gatts ◽  
Shiyu Liu ◽  
Scott Wayne ◽  
Nigel Clark ◽  
...  
Keyword(s):  
Natural Gas ◽  
Flame Propagation ◽  
Combustion Process ◽  
Propagation Speed ◽  
Spark Ignition ◽  
Boost Pressure ◽  
Stoichiometric Mixture ◽  
Process Data ◽  
Intake Pressure ◽  
Flame Propagation Speed

This research investigated the combustion process of an AVL Model LEF/Volvo 5312 single cylinder engine configured to simulate the operation of a heavy-duty spark ignition (SI) natural gas (NG) engine operated on stoichiometric mixture. The factors affecting the combustion process that were examined include intake pressure, spark timing (ST), and the addition of diluents including nitrogen (N2) and carbon dioxide (CO2) to the NG to simulate low British thermal unit (BTU) gases. The mixing of diluents with NG is able to slow down the flame propagation speed, suppress the onset of knock, and allow the engine to operate on higher boost pressure for higher power output. The addition of CO2 was more effective than N2 in suppressing the onset of knock and slowing down the flame propagation speed due to its high heat capacity. Boosting intake pressure significantly increased the heat release rate (HRR) evaluated on J/°CA basis which represents the rate of mass of fuel burning. However, its impact on the normalized HRR evaluated on %/°CA basis, representing the flame propagation rate, was relatively mild. Boosting the intake pressure from 1.0 to 1.8 bar without adding diluents increased the peak HRR to 1.96 times of that observed at 1.0 bar. The increase was due to the burning of more fuel (about 1.8 times), and the 12.9% increase in the normalized HRR. The latter was due to the shortened combustion duration from 23.6 to 18.2 °CA, a 22.9% reduction. The presence of 40% CO2 or N2 in their mixture with NG increased the peak cylinder pressure (PCP) limited brake mean effective pressure (BMEP) from 17.2 to about 20.2 bar. The combustion process of a turbocharged SI NG engine can be approximated by referring to the HRR measured under a naturally aspirated condition. This makes it convenient for researchers to numerically simulate the combustion process and the onset of knock of turbocharged SI NG engines using combustion process data measured under naturally aspirated conditions as a reference.

Effects of Vortex Stretching and Merging on Flame Propagation Speed in Vortex Bursting

2019 ◽  
Vol 2019 (0) ◽  
pp. J05107P
Author(s):  
Yoh KABUTOYA ◽  
Takashi TAKAYAMA ◽  
Masahisa SHINODA ◽  
Hiroshi YAMASHITA
Keyword(s):  
Flame Propagation ◽  
Propagation Speed ◽  
Flame Propagation Speed
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