Synergistic Effect of Soot Formation in Ethylene/Propane Co-Flow Diffusion Flames at Elevated Pressures

2021 ◽  
Author(s):  
Dongsheng Zheng ◽  
Xin Hui ◽  
Xin Xue ◽  
Weitao Liu
Keyword(s):  
Synergistic Effect ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Total Carbon ◽  
Light Extinction ◽  
Flame Height ◽  
Carbon Mass

Abstract The synergistic effect of soot formation refers to the interaction between different fuels during soot forming processes, which results in higher soot formation than any individual fuels. The present study experimentally investigates the synergistic effect of soot formation in co-flow diffusion flames of propane/ethylene fuel mixtures. The total carbon mass flow rate of the propane/ethylene mixture was kept constant at 0.5 mg/s, and the propane carbon ratio (RC) was defined as the ratio of carbon mass flow rate of propane to the total carbon mass flow rate. The laser-induced incandescence (LII) and light extinction (LE) techniques were applied to measure the soot volume fractions (SVF) at pressures of 0.1–0.5 MPa. The results showed strong synergistic effect in propane/ethylene mixtures at atmospheric conditions; however, increasing pressure weakens the synergistic effect. The LII intensity contours showed that the soot formation zone extends when synergistic effect occurs at RC = 0.1 and 0.2 for 0.1 and 0.3 Mpa. The normalized peak SVF showed that synergistic effect monotonically becomes weak with increasing pressure from 0.1 to 0.3 Mpa; meanwhile, the it still stayed strong at 0.2 Mpa when using normalized maximum soot yield, and then turned to be weaker as pressure increases. Further comparison analysis of the SVF profiles between RC = 0 and 0.1 revealed that the synergistic effect occurs at the two-wing area of the sooty flame at low axial flame height, and then gradually becomes stronger with increasing axial flame height in the soot zone for 0.1–0.3 Mpa. To illustrate the pressure effects on synergistic soot formation, numerical analysis in homogeneous closed reactor was conducted and it was found that The PAHs formation competition between C3H3 pathway and HACA mechanism results in the different soot formation phenomenon of ethylene/propane flames.

Mechanism of the Effect of Dilution With Different Inert Gases on Smoke Point of Propylene Diffusion Flames

2004 ◽  
Author(s):  
S. F. Goh ◽  
S. R. Gollahalli
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Diffusion Flames ◽  
Smoke Point ◽  
Inert Gases ◽  
Inert Gas ◽  
Flame Height ◽  
Point Condition ◽  
Gas Dilution

An experimental study to compare the smoking characteristics of diffusion flames of propylene diluted nitrogen, argon, carbon dioxide and helium was performed. The mass flow rate of propylene at smoke point condition, which was defined as the critical fuel mass flow rate (CFMFR), was first determined. Then, CFMFR was divided into ten different fractions for the study of the mechanism of inert gas dilution on smoke point. The mass flow rate of each different inert gas to achieve the smoke point condition was then determined in the same manner. Flame radiation and the visible flame height for all the diluted fuel flames were measured. The axial soot concentration profiles of nitrogen-diluted smoke point flames were also measured using the laser induced incandescence (LII) method for selective conditions. The inert gas dilution study showed two distinct regions (chemical and momentum controlled regions). The study shows the amount diluent needed to achieve smoke point was in the decreasing order of Ar, CO2, N2 and He on mass basis. The analysis of the results showed that the main reason for this phenomenon was the heat sink capability of the gas. Hence, the specific heat of the gas was an important parameter. In general, nitrogen-diluted flames had higher flame length than other inert gas diluted flames. At higher CFMFR, in helium-diluted flames radiation was higher than in other flames.

Computational Study of Fuel Dilution Effect on the Soot Formation in Methane-Air Laminar Confined Diffusion Flame

2013 ◽  
Author(s):  
Achin Kumar Chowdhuri ◽  
Arindam Mitra ◽  
Somnath Chakraborti ◽  
Bijan Kumar Mandal
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Diffusion Flame ◽  
Volume Fraction ◽  
Soot Formation ◽  
Soot Volume Fraction ◽  
Flame Height ◽  
Fuel Jet ◽  
Fuel Stream

Although diffusion flame is free from many problems associated with premixed flame, soot formation is a major problem in diffusion flame. The techniques of dilution of fuel or air with inert gases such as nitrogen and argon are used to decrease soot level in the flame. In this work, a CFD code has been developed to predict the flame height, soot volume fraction and soot number density in an axisymmetric laminar confined methane-air diffusion flame after diluting the fuel with nitrogen. The temperatures of the air and fuel at inlet are taken as 300K. Mass flow rate of the fuel stream is considered as 3.71×10−6 kg/s and mass flow rate of the air is taken as 2.2104×10−6 kg/s. The total mass flow rate through the central jet (fuel jet) is, however, kept constant. The radiation effect is also included through an optically thin radiation model. An explicit finite difference technique has been adopted for the numerical solution of reacting flow and two equations soot model with variable thermodynamic and transport properties. The prediction shows that flame height decreases with the addition of nitrogen to the fuel. Temperature of the flame is considerably reduced in the given computational domain. Both soot volume fraction and soot number density decrease with dilution by adding nitrogen in the fuel jet. The soot formation at different nitrogen dilution level of 0%, 10%, 20%, 30%, 40% and 50% are plotted and the soot get considerably reduced as the concentration of nitrogen is increased in the fuel stream.

The Liftoff Properties of Dimethyl Ether Jet Diffusion Flames With Preheating

2013 ◽  
Author(s):  
Jie Zhou ◽  
Yuhua Ai ◽  
Wenjun Kong
Keyword(s):  
Ambient Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Diffusion Flames ◽  
Thermal Buoyancy ◽  
Jet Diffusion Flames ◽  
Lifted Flames ◽  
Low Mass ◽  
Jet Velocity

Liftoff properties of DME laminar axisymmetric diffusion flames were investigated experimentally with emphasis on the preheating effects. At room temperature, DME presented a different liftoff phenomenon from the non-oxygenated hydrocarbon fuels. It could not be lifted off directly by increasing the jet velocity except for far field ignition at relatively low mass flow rate. When fuel and dilution were preheated, the DME flame could be lifted off directly by increasing the jet velocity. The range of the mass flow rate of stabilized DME liftoff flames became much narrower and the liftoff height became much smaller at fuel preheating than that at ambient temperature. With the increase of the jet temperature, the DME liftoff flames exhibited as one of the following three types: stationary lifted flames, stable oscillating lifted flames and unstable oscillating lifted flames. Stationary lifted flames existed when the initial temperature was relatively low (less than 350 K). Stable oscillating lifted flames were observed at relatively high preheated temperature (about 350 K ∼ 750 K), and the trajectory of the liftoff flame base was nearly sinusoidal. Both the oscillating frequency and amplitude increased with the preheating temperature. The oscillating lifted flames were caused by thermal buoyancy effect, inertia and the instability in the inner flow. When the jet temperature exceeded 750 K, the oscillating lifted flames became unstable and easily to be blown out. The flame base of the stabilized DME liftoff flame had a tribrachial structure at both ambient temperature and elevated temperature.

Experimental and Numerical Analysis of Carbon Black Formation in Hydrocarbon/Air Diffusion Flames

2010 ◽  
Author(s):  
D. F. Heravi ◽  
H. M. Heravi ◽  
K. Bashirnezhad ◽  
Hassan Sanaei ◽  
Amirhomayun Samiee
Keyword(s):  
Carbon Black ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Mass Fraction ◽  
Diffusion Flames ◽  
Flame Temperature ◽  
Gravimetric Method ◽  
Numerical Predictions ◽  
Air Diffusion

Carbon black has been widely used in industry, especially in rubber and plastic production. The present study is concerned with measuring and simulating the carbon black formation process in Propane-air and Acetylene-Air diffusion flames. The carbon black concentrations in the furnace have been measured by means of a soot pump and gravimetric method. The flue gas analysis is also done by means of Testo XL-350 Gas Analyzer. The numerical predictions are carried out with the CFD code, Fluent. The chemical reaction formulation relates the production of the carbon black to the incomplete combustion and pyrolysis of propane and Acetylene as both the main gas and the feedstock. The effects of feedstock mass flow rate, the position of feedstock injection, the feedstock material and the shape of the furnace on carbon black are studied. The results show the effect of temperature on soot and carbon black formation in which as the temperature increases the soot and carbon black mass fraction is also increased. The results also show that as the feedstock mass flow rate increases the formation of the carbon black is increased up to point where the mass flow rate of feed stock is three times greater than the mass flow rate of the main gas and after that the carbon black production rate starts decreasing because of the decreasing of temperature due to cold fuel injection to the furnace. The position of feedstock injection affects the mixing process of air and fuel, and complete mixing causes the temperature to be increased. The injection of feedstock in the pre-combustion zone influences the maximum of the flame temperature. As the hydrocarbon initially pyrolyzes to acetylene and afterwards acetylene breaks into soot and carbon black in the present study acetylene is used as feedstock, the results show huge increasing of soot and carbon black mass fraction in the products. The results also show that predictions and the experimental measurements are in good agreement.

Soot Formation With Light Extinction and Grayscale Extraction Methods Applied to Ethanol-Gasoline Blends Laminar Flame

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Shengli Wei ◽  
Jie Chen ◽  
Rui Xu ◽  
Tongyuan Ding ◽  
Xiqian Zhao
Keyword(s):  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Laminar Flame ◽  
Flame Structure ◽  
Extraction Methods ◽  
Light Extinction ◽  
Flame Height ◽  
Laminar Diffusion Flames ◽  
Mass Flowrate

Abstract In this paper, the two-dimensional parallel light extinction method was carried out to study the soot formation in laminar diffusion flames of four different ethanol-gasoline blends, of which ethanol volume fractions ranging from 0% up to 100% (E0, E20, E80, and E100). The flame images were processed synthetically via matlab to accurately calculate the flame height. In addition, the flame structure was redefined as three zones to observe the soot formation. The results indicate that the flame height changes with the variation of gas volume flowrate and fuel mass flowrate during the experiment. In terms of soot formation, as the volume fraction of ethanol increases, the proportion of soot forming zone decreases, while the area of blue flame zone grows. Simultaneously, the transition zone accounts for about 21% of the total flame area, which has no significant change with the increase of ethanol volume fraction.

scholarly journals Experimental Investigation of Oxygen Addition to Fuel on Soot Formation in Laminar Coflow Diffusion Flames of Ethylene and Propane

2006 ◽  
Author(s):  
Fengshan Liu ◽  
Kevin A. Thomson ◽  
Gregory J. Smallwood
Keyword(s):  
Flow Rate ◽  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Soot Volume Fraction ◽  
Oxygen Flow Rate ◽  
Flame Height ◽  
Fuel Flow Rate ◽  
Fuel Flow ◽  
Oxygen Addition

Investigation of the effect of oxygen addition to fuel on the visible flame appearance and soot formation characteristics of laminar diffusion flames is important to gain comprehensive understanding of gas-phase combustion chemistry and its interaction with soot chemistry. This paper reports experimental results of oxygen addition to fuel on the visible flame height and soot volume fraction distributions in axisymmetric coflow laminar ethylene and propane diffusion flames at atmospheric flames. The carbon flow rate was maintained constant in all the experiments. Although many experimental studies have been conducted in the literature in this topic, the present investigation aimed at providing spatially resolved soot volume fraction distributions over the entire range of oxygen addition from no oxygen addition up to the point of flashback while keeping the carbon mass flow rate constant. The level of oxygen added to fuel right before flashback is about 45% (the percentage of oxygen addition is always by volume in this study) of the fuel flow rate in the ethylene flame and 300% of the fuel flow rate in the propane flame. As the added oxygen amount to ethylene increases, the visible flame height first increases. When the added oxygen flow rate is about 13% of the fuel flow rate, the flame becomes smoking, i.e., soot escapes from the flame tip. When the oxygen flow rate reaches about 42% of the fuel flow rate, the flame stops smoking. When oxygen was added to propane, the visible flame height linearly decreases with increasing the amount of oxygen. These very different effects of oxygen addition to ethylene and propane indicate that oxygen plays a drastically different role in the chemical pathways leading to soot formation in ethylene and propane flames. Distributions of soot volume fractions in these flames were measured using a 2D light attenuation technique coupled with the Abel inversion. The present study provides valuable experimental data for validating soot models.

scholarly journals Effects of aromatic on soot characteristics of aviation fuel surrogates in diffusion flames

2015 ◽  
Vol 18 (4) ◽  
pp. 55-64
Author(s):  
Thong Duc Hong ◽  
Osamu Fujita
Keyword(s):  
Diffusion Flames ◽  
Soot Formation ◽  
Linear Functions ◽  
Aviation Fuel ◽  
Light Extinction ◽  
Flame Height ◽  
Aircraft Engines ◽  
Mass Consumption ◽  
Function Of Two Variables ◽  
Fuel Surrogates

Co-annular smoke-free laminar diffusion wick-fed flames of dodecane and its blended with various amounts of propylbenzene of 10, 20, 25 vol.% have been used to study soot formation characteristics. Dodecane and propylbenzene are selected as the surrogates for paraffin class and aromatic class of aviation fuel. A light extinction method is adopted to determine the total soot volume (TSV) as a function of flame height (Hf) and fuel mass consumption rate (FMCR). An empirical model has been built to predict soot formation of dodecane and propylbenzene (Do/PB) mixtures as the function of two variables of FMCR and concentration of propylbenzenet (%PB). TSVs of Do/PB mixtures increase with increasing Hf, FMCR and %PB. The effect of Hf, FMCR and %PB on soot formation are respectively expressed as the quadratic, power law and linear functions. The result of current work creates a database for optimizing the trade-off impacts of aromatic in aviation fuel. This information is of high importance when blending aromatic to bioparaffins, which is produced from triglycerides and fatty acids in the vegetable by hydrotreating process, for using as a fuel in aircraft engines.

The standard unit mass flow rate of gas-liquid mixtures

2020 ◽  
pp. 13-16
Author(s):  
V.N. Petrov ◽  
◽  
V.F. Sopin ◽  
L.A. Akhmetzyanova ◽  
Ya.S. Petrova ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Liquid Mixtures ◽  
Unit Mass ◽  
Standard Unit

Prediction of Leakage Mass Flow Rate Through Gas Springs

1987 ◽  
Author(s):  
Roberto Bruno Bossio ◽  
Vincenzo Naso ◽  
Marian Cichy ◽  
Boleslaw Pleszewski
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate
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