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

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.

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The Liftoff Properties of Dimethyl Ether Jet Diffusion Flames With Preheating

Volume 1B: Combustion, Fuels and Emissions ◽

10.1115/gt2013-95287 ◽

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.

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Transient Response of a Cross Flow Heat Exchanger Subjected to Temperature and Flow Perturbations

Volume 8A: Heat Transfer and Thermal Engineering ◽

10.1115/imece2015-52562 ◽

2015 ◽

Cited By ~ 3

Author(s):

Karthik Silaipillayarputhur ◽

Stephen A. Idem

Keyword(s):

Heat Exchanger ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Heat Exchangers ◽

Cross Flow ◽

Transient Performance ◽

Numerical Predictions ◽

Minimum Capacity ◽

Flow Heat

The transient performance of a multi-pass cross flow heat exchanger subjected to temperature and mass flow rate perturbations, where the heat exchanger flow circuiting is neither parallel flow nor counter flow, is considered in this work. A detailed numerical study was performed for representative single-pass, two-pass, and three-pass heat exchangers. Numerical predictions were obtained for cases where the minimum capacity rate fluid was subjected to a step change in inlet temperature in absence of mass flow rate perturbations. Likewise, numerical predictions were obtained for the heat exchangers operating initially at steady state, where a step mass flow rate change of the minimum capacity rate fluid was imposed in the absence of any fluid temperature perturbations. The transient performance of this particular heat exchanger configuration subjected to these temperature and flow disturbances has not been discussed previously in the available literature. In the present study the energy balance equations for the hot and cold fluids and the heat exchanger wall were solved using an implicit central finite difference method. A parametric study was conducted by varying the dimensionless quantities that govern the transient response of the heat exchanger over a typical range of values. Because of the storage of energy in the heat exchanger wall, and finite propagation times associated with the inlet perturbations, the outlet temperatures of both fluids do not respond instantaneously. The results are compared with previously published transient performance predictions of multi-pass counter flow and parallel flow heat exchangers.

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

ASME 2004 Power Conference ◽

10.1115/power2004-52134 ◽

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.

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

10.1115/gt2021-58622 ◽

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.

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Two-Dimensional Numerical Study of Temperature, Species Distributions in Coflow Laminar Diffusion Flames

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.516-517.80 ◽

2012 ◽

Vol 516-517 ◽

pp. 80-83

Author(s):

You Ning Xu ◽

Jun Rui Shi ◽

Zhi Jia Xue ◽

Shu Qun Wang ◽

Mao Zhao Xie

Keyword(s):

Gas Phase ◽

Mass Fraction ◽

Diffusion Flames ◽

Numerical Study ◽

Flame Temperature ◽

Species Distributions ◽

Phase Reaction ◽

Laminar Diffusion Flames ◽

Gas Phase Reaction ◽

Air Diffusion

Abstract. temperature and species distributions of an atmosphere coflow laminar CH4/air diffusion flame was studied by numerical simulation. We solve the steady equations for the species mass fraction, energy, momentum with detailed gas-phase reaction mechanism and complex thermal and transport properties to predict the velocity, temperature, species distributions for different dilute level. Results indicated that the predicted temperature and species are in excellent with available experiment date at different dilute level. In addition, it is indicated that adding N2in the fuel has a significant influence on the flame temperature and species distribution.

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Numerical study of the effect of gas-to-liquid ratio on the internal and external flows of effervescent atomizers

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-2017-0125 ◽

2018 ◽

Vol 42 (4) ◽

pp. 444-456 ◽

Cited By ~ 1

Author(s):

Milad Mousavi ◽

Ali Dolatabadi

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Internal Flow ◽

Operating Conditions ◽

Liquid Ratio ◽

Spray Cone ◽

Numerical Predictions ◽

Gas To Liquid ◽

Discharge Orifice

In an effort to capture the complex evolving interface of internal and external flow in an effervescent atomizer, a compressible Eulerian method, along with the volume-of-fluid method coupled with the large eddy simulation model, are employed in a two-phase flow system. Water is injected into the atomizer with a constant mass flow rate of 0.0133 kg/s (i.e., 800 mL/min). The mass flow rate of air is adjusted to vary the gas-to-liquid ratio (GLR) from 0.55% to 2.6%. It is observed that the increase in the GLR is accompanied by an evolution of the internal flow from a complex bubbly flow to an annular flow, which consequently reduces the liquid film thickness at the discharge orifice. Further studies on the internal pressure illustrate the critical condition, which leads to choked flow and pressure oscillations at the discharge orifice. Increasing the GLR was found to affect the internal flow, resulting in changes to primary atomization parameters such as a shortening of the breakup length and a widening of the spray cone angle. The numerical predictions are in good agreement with the experimental results under the same operating conditions.

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Experimental and Numerical Study of Supercritical Carbon Dioxide Flow Through Valves

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4032640 ◽

2016 ◽

Vol 2 (3) ◽

Author(s):

Haomin Yuan ◽

Mark Anderson

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Validation Data ◽

Choked Flow ◽

Numerical Predictions ◽

Valve Model ◽

Supercritical Carbon

The supercritical carbon dioxide (sCO2) Brayton cycle shows advantages such as high efficiency, compactness, and low capital cost. These benefits make it a competitive candidate for future-generation power-conversion cycles. In order to study this cycle, valve characteristics under sCO2 flow conditions must be studied. However, the traditional models for valves may not be accurate due to the real gas property of sCO2. In this study, this problem was studied both experimentally and numerically. A small valve was tested in the authors’ experiment facility first to provide validation data. For this valve, numerical predictions of mass flow rate agree with experimental data. Then, simulations were scaled up to valves in a real power-cycle design. The traditional gas-service valve model fails to predict mass flow rate at low-pressure ratios. A modification was proposed to improve the current gas-service valve model by changing the choked-flow check.

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An Experimental Study on Flame Puffing of a Swirl Partially Premixed Combustion under Varying Mass Flow Rate of Primary Air

Energies ◽

10.3390/en11071916 ◽

2018 ◽

Vol 11 (7) ◽

pp. 1916

Author(s):

Zhongya Xi ◽

Zhongguang Fu ◽

Syed Sabir ◽

Xiaotian Hu ◽

Yibo Jiang

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Equivalent Width ◽

Flame Temperature ◽

Dominant Frequency ◽

Partially Premixed ◽

Swirl Flame ◽

The Impact ◽

Varying Mass

It is of practical significance to understand the flame puffing behavior under varying mass flow rate of primary air ṁpri. An experiment was conducted to study the impact of ṁpri on flame puffing in a swirl partially premixed combustor, the puffing behavior of six significant flame properties was examined. The results showed that almost every spectrum had two fundamental frequencies, which is different from the single-peak spectrum of non-swirl flame. The flame heat-release rate, flame area, and flame equivalent width had identical dominant frequency and sub-dominant frequency, both decreased with the increasing of ṁpri. It was attributed to the decreased overall flame temperature caused by the improved mixing of fuel and primary air. All measured frequencies were in the range of 3–14 Hz, but the predicted frequencies from the theoretical models based on non-swirl flame were larger than the measured. This indicates the puffing frequency of swirl flame was much more sensitive to the variation in ṁpri than the frequency of non-swirl flame. Moreover, the amplitude of flame length was the smallest in all properties, with the most weakened oscillating intensity. While the amplitude of the flame area and flame equivalent width were the largest, with the strongest oscillation level. Consequently, the flame puffing is mainly attributed to the oscillation in width direction.

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Microscale Desorption Based on Membrane Separation

Volume 4 ◽

10.1115/ht-fed2004-56756 ◽

2004 ◽

Author(s):

Jonathan D. Thorud ◽

Jeremy J. Siekas ◽

James A. Liburdy ◽

Deborah V. Pence

Keyword(s):

Heat Flux ◽

Binary Mixture ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Mass Flux ◽

Heat Input ◽

Mass Fraction ◽

Inlet Flow ◽

Inlet Flow Rate

A scheme to achieve high desportion rates in a microscale system has been conceived based on the use of a hydrophobic porous membrane forming one wall of a high aspect ratio channel. To accomplish desorption, vapor is drawn through the membrane, during the addition of heat, as the binary mixture flows along the channel. The channel geometry is designed to achieve a thin film of binary mixture (lithium bromide and water) that is approximately 350 microns thick, while achieving a high membrane surface area which is approximately 3 cm × 6 cm. Vapor is drawn from the channel by creating a pressure differential across the membrane. Experiments were run varying the inlet mass flow rate, heat input, and pressure difference across the membrane, for an inlet mass fraction of 0.41. Mass fraction increases through the channel were up to 0.05. It is shown that the mass flux of vapor per mass flow rate into the channel decreases as the inlet flow rate increases, for a given heat flux. Also, the mass flux of vapor is linearly dependent on the heat input rate and not a function of inlet flow rate or pressure differential for the range of conditions studied. Images within the channel show bubble formation and desorption through the membrane under high heat flux and low inlet flow conditions.

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