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Mehdi Bidabadi - One of the best experts on this subject based on the ideXlab platform.

  • volatization combustion of biomass particles in random media mathematical modeling and analyze the effect of lewis number
    Chemical Engineering and Processing, 2018
    Co-Authors: Mehdi Bidabadi, Mohammadali Harati, Ebrahim Yaghoubi, Mohammad Hossein Doranehgard, Qingang Xiong, Pouria Aghajannezhad
    Abstract:

    Abstract In this work, a mathematical model is proposed to model volatilization and combustion of micro organic dust particles. In contrast with previous studies, random combustion of Biomass particles (Lycopodium) and analyze the effect of different Lewis number on the combustion properties is investigated. It is assumed that Flame structure is consisted of preheat or volatilization Zone, reaction Zone and post Flame Zone. Also, different Lewis numbers are applied in governing equations. For modeling random combustion, the source term in energy equation has been modeled by use of random states for volatilization of particles in preheat Zone. For this regard, different groups which contains random number of particles and sense a random temperature in the preheat Zone has been considered. In this analysis, the impact of random combustion, Lewis number and size of particles on the combustion properties of Biomass particles such as: burning velocity, Flame temperature and effective equivalence ratio are studied. Consequently, comparison made between results obtained from random model by experimental data, showed that the random model have a better agreement with experimental data than non-random model.

  • the influence of radiation on the Flame propagation through micro organic dust particles with non unity lewis number
    Journal of The Energy Institute, 2014
    Co-Authors: Mehdi Bidabadi, S Montazerinejad, Sayyed Aboozar Fanaee
    Abstract:

    Abstract In this paper, the analytical study of effects of radiation and non-unity Lewis number on the laminar premixed Flames of organic dust clouds has been done. The research is focused on a combustion model for premixed Flames and the Flame structure is composed of preheat-vaporization, narrow reaction and finally the post-Flame Zone. The normalized governing equations with help of boundary and matching conditions are solved by perturbation method. The results show that increasing equivalence ratio and decreasing Lewis number are resulted in the increase of Flame temperature and burning velocity. For the sake of this model validation, fuel conversion is compared by published experimental data and shows an acceptable agreement.

  • an analytical model for Flame propagation through moist lycopodium particles with non unity lewis number
    International Journal of Engineering Transactions B: Applications, 2014
    Co-Authors: Mehdi Bidabadi, Seyed Alireza Mostafavi, Farzad F Dizaji, Beidaghy H Dizaji
    Abstract:

    In this investigation, the structure of one-dimensional Flame propagation in uniform cloud of volatile organic particles has been analyzed in which the structure of Flame is divided into three Zones. The first Zone is preheat Zone which is divided into three subZones itself. In the first subZone (heating), particle cloud is heated until the moist particles reach to vaporization temperature (water vapor). In the next subZone (drying), particle moisture comes out, and in the final subZone the pyrolysis phenomenon takes place. The second Zone is the reaction Zone, and the last one is the post-Flame Zone. In this research, an analytical method is used in order to solve the governing equations of particle cloud combustion in aforementione d Zones. The overall investigation of this study leads to a non-linear burning velocity correlation. Consequently, the results show that a decrease in particle moisture content or an increase in equivalence ratio ( u ϕ ) or Lewis number causes to increase in moisture evaporation and devolatization rates, and consequently both Flame temperature and burning velocity increase

  • the effect of lewis and damkohler numbers on the Flame propagation through micro organic dust particles
    International Journal of Thermal Sciences, 2010
    Co-Authors: Mehdi Bidabadi, Ali Haghiri, Alireza Rahbari
    Abstract:

    In this study, the role of Lewis and Damkohler numbers on the premixed Flame propagation through micro-organic dust particles is investigated. It is presumed that the fuel particles vaporize first to yield a gaseous fuel, which is oxidized in the gas phase. In order to simulate the combustion process, the Flame structure is composed of four Zones; a preheat Zone, a vaporization Zone, a reaction Zone and finally a post Flame Zone, respectively. Then the governing equations, required boundary conditions and matching conditions are applied for each Zone and the standard asymptotic method is used in order to solve these differential equations. Consequently the important parameters on the combustion phenomenon of organic dust particles such as gaseous fuel mass fraction, organic dust mass fraction and burning velocity with the various numbers of Lewis, Damkohler and the onset of vaporization are plotted in figures. This prediction has a reasonable agreement with experimental data of micro-organic dust particle combustion.

Wei Wu - One of the best experts on this subject based on the ideXlab platform.

  • comparative study on microwave plasma assisted combustion of premixed and nonpremixed methane air mixtures
    Combustion Science and Technology, 2015
    Co-Authors: Wei Wu, Che A. Fuh, Chuji Wang
    Abstract:

    Employing a novel microwave plasma-assisted combustion (PAC) facility, we conducted a comparative study on PAC of premixed and nonpremixed methane/air mixtures. Results showed that three different reaction Zones (plasma Zone, hybrid plasma-Flame Zone, and Flame Zone) exist, regardless of the fuel injection patterns of the premixed or nonpremixed. Different fuel injection patterns had different optical emission spectra for the hybrid Zones and Flame Zones, with a major difference being the presence or absence of emissions from CH and C2. A U-shaped ignition curve of plasma power versus fuel equivalence ratio was observed in the premixed PAC, whereas an approximately linear increasing line was in the nonpremixed PAC. Pulsed cavity ringdown spectroscopy was also utilized to measure absolute number densities of the ground state OH(X) radicals in the Flame Zones for both fuel patterns. Results showed different number density profiles along the Flame propagation direction between the premixed and nonpremixed PAC.

  • roles of the state resolved oh a and oh x radicals in microwave plasma assisted combustion of premixed methane air an exploratory study
    Combustion and Flame, 2014
    Co-Authors: Chuji Wang, Wei Wu
    Abstract:

    Abstract We report a novel microwave plasma-assisted combustion (PAC) system that is developed as a new test platform to study roles of plasma in PAC. The system included two major components, an atmospheric pressure microwave plasma cavity and a cross-shape quartz combustor. This new PAC system allows one to study PAC using complicated yet well-controlled combinations of operating parameters, such as fuel equivalence ratio ( ϕ ), fuel mixture flow rate, plasma gas flow rate, plasma gases, symmetric or asymmetric fuel-oxidant injection patterns, with and without plasma. In this work, ignitions at the fuel (lean and rich) flammability limits at different plasma powers and fuel flow rates were investigated. The ignition curves of plasma power versus ϕ FL at the different flow rates revealed a stretched U-shape, showing clear evidences of the plasma enhancement effects on ignition and Flame stabilization, i.e. the fuel lean flammability limit ( ϕ LFL ) was extended to ϕ  = 0.2, as compared to ϕ  = 0.6 at the same combustion parameters except with no plasma. Optical emission spectroscopy (OES) showed that the combustor had three distinct reaction Zones: plasma Zone, hybrid plasma-Flame Zone, and Flame Zone; and each of the reaction Zones was well defined by its OES features. Furthermore, a detailed survey of OES of OH (A–X) conducted along the plasma jet axis ( x direction) with a spatial resolution of 0.5 mm revealed that OH(A) had a double-peak feature in its relative emission intensity curve (I ∼  x ) in the hybrid Zone where plasma-assisted ignition (PAI) started, as evidenced by a significant surge of OH(A) and by a large increase in OH rotational temperature, i.e. from 1450 K to 2400 K. Moving from the hybrid Zone to the Flame Zone, OH(A) decreased by more than four orders of magnitude. However, the electronic ground state OH(X) measured simultaneously using pulsed cavity ringdown spectroscopy around 308 nm showed that absolute number density of the OH(X) decreased by smaller than a factor of ten from the downstream of the hybrid Zone to the Flame Zone. The different changing rates of the OH(A) and OH(X) radicals from the hybrid Zone to the Flame Zone allow us to propose a hypothesis that if both the electronically excited state OH(A) and the electronic ground state OH(X) assisted the ignition and Flame stabilization processes, the role of OH(X) radicals was more dominant in the Flame stabilization but the role of OH(A) radicals was more dominant in the ignition enhancement.

  • simultaneous measurements of oh a and oh x radicals in microwave plasma jet assisted combustion of methane air mixtures around the lean burn limit using optical emission spectroscopy and cavity ringdown spectroscopy
    Journal of Physics D, 2013
    Co-Authors: Chuji Wang, Wei Wu
    Abstract:

    We report a new plasma-assisted combustion system, in which a continuous atmospheric argon microwave plasma jet is employed to enhance combustion of methane/air mixtures in different fuel equivalence ratios (?) ranging from 0.35 to 1.5. The combustor has three distinct reaction Zones along the jet axis (the combustion Flame direction): the pure plasma Zone, the hybrid plasma-Flame Zone and the combustion Flame Zone. Each of the three Zones is clearly defined by its emission spectral fingerprints. The plasma Zone was featured by strong emissions from OH and NH electronic bands and atomic lines of Ar, H? and H?. In the hybrid Zone where the plasma jet met fuel mixtures, emission spectra were dominated by OH, NH and CN transitions and by weak or no atomic transitions. In the combustion Flame Zone, only weak OH emissions were observed. Simulations of optical emission spectroscopy (OES) yielded gas kinetic temperatures to be 1175???50?K, 1450???50?K and 1865???50?K in each of the three Zones, respectively. The plasma-enhancement effect was investigated by comparing the lean-burn limits of the combustion with and without plasma. At the same fuel mixture flow rate of 1.0 standard litre per minute and plasma power of 100?W, the lean-burn limit in terms of the fuel equivalence ratio ? was extended from 0.72 without assistance of the plasma to 0.35 with assistance of the plasma. In addition to OES that was employed to characterize the excited state species including OH(A) in the three different Zones, pulsed cavity ringdown spectroscopy was utilized to measure absolute number densities of the ground state OH(X) using the OH A?X (0?0) R2 (1) line in different locations in the Flame Zone at ??=?0.51, 0.87, 1.10 and 1.45. For rich and lean combustions, significantly different OH(X) number densities and density profiles in the Flame Zone were observed. At ??=?0.51, the OH(X, V??=?0, J??=?0.5) number density increased from 2.29???1015?molecule?cm?3 at the combustor nozzle to the maximum, 3.13???1015?molecule?cm?3 at 2?mm downstream, and to the lowest detectable level of 0.12???1015 molecule cm?3 in the far downstream where optical emissions were too weak to be detected. Results from the simultaneous measurements of the electronically excited state OH(A) and the ground state OH(X) allow us to discuss the roles of OH(A) and OH(X) in the plasma-assisted ignition and the Flame stabilization, respectively.

Richard A Yetter - One of the best experts on this subject based on the ideXlab platform.

  • effect of particle size on combustion of aluminum particle dust in air
    Combustion and Flame, 2009
    Co-Authors: Ying Huang, Vigor Yang, Grant Risha, Richard A Yetter
    Abstract:

    Abstract The combustion of aluminum particle dust in a laminar air flow is theoretically studied under fuel-lean conditions. A wide range of particle sizes at nano and micron scales is explored. The Flame speed and temperature distribution are obtained by numerically solving the energy equation in the Flame Zone, with the particle burning rate modeled as a function of particle diameter and ambient temperature. The model allows for investigation into the effects of particle size, equivalence ratio, and chemical kinetics on the burning characteristics and Flame structures of aluminum-particle/air mixtures. In addition, the Flame behavior with ultra-fine particles in the sub-nanometer range is examined by asymptotically treating particles as large molecules. Calculated Flame speeds show reasonable agreement with experimental data. As the particle diameter decreases from the micron to the nano range, the Flame speed increases and the combustion transits from a diffusion-controlled to a kinetically controlled mode. For micron-sized and larger particles, the Flame speed can be correlated with the particle size according to a d − m relationship, with m being 0.92. For nano-particles, a d −0.52 or d −0.13 dependence is obtained, depending on whether the d 1.0 - or d 0.3 -law of particle burning time is implemented in the Flame model, respectively. No universal law of Flame speed exists for the entire range of particle sizes.

  • combustion of bimodal nano micron sized aluminum particle dust in air
    31st International Symposium on Combustion, 2007
    Co-Authors: Ying Huang, Vigor Yang, Grant Risha, Richard A Yetter
    Abstract:

    Abstract The combustion of bimodal nano/micron-sized aluminum particles with air is studied both analytically and experimentally in a well-characterized laminar particle-laden flow. Experimentally, an apparatus capable of producing Bunsen-type premixed Flames was constructed to investigate the Flame characteristics of bimodal-particle/air mixtures. The Flame speed is positively affected by increasing the mass fraction of nano particles in the fuel formulation despite the lower Flame luminosity and thicker Flame Zone. Theoretically, the Flames are assumed to consist of several different regimes for fuel-lean mixture, including the preheat, Flame, and post Flame Zones. The Flame speed and temperature distribution are derived by solving the energy equation in each regime and matching the temperature and heat flux at the interfacial boundaries. The analysis allows for the investigation of the effects of particle composition and equivalence ratio on the burning characteristics of aluminum-particle/air mixtures. Reasonable agreement between theoretical results and experimental data was obtained in terms of Flame speed. The Flame structure of a bimodal particle dust cloud may display either an overlapping or a separated configuration, depending on the combustion properties of aluminum particles at different scales. At low percentages of nano particles in the fuel formulation, the Flame exhibits a separated spatial structure with a wider Flame regime. At higher nano-particle loadings, overlapping Flame configurations are observed.

Chuji Wang - One of the best experts on this subject based on the ideXlab platform.

  • comparative study on microwave plasma assisted combustion of premixed and nonpremixed methane air mixtures
    Combustion Science and Technology, 2015
    Co-Authors: Wei Wu, Che A. Fuh, Chuji Wang
    Abstract:

    Employing a novel microwave plasma-assisted combustion (PAC) facility, we conducted a comparative study on PAC of premixed and nonpremixed methane/air mixtures. Results showed that three different reaction Zones (plasma Zone, hybrid plasma-Flame Zone, and Flame Zone) exist, regardless of the fuel injection patterns of the premixed or nonpremixed. Different fuel injection patterns had different optical emission spectra for the hybrid Zones and Flame Zones, with a major difference being the presence or absence of emissions from CH and C2. A U-shaped ignition curve of plasma power versus fuel equivalence ratio was observed in the premixed PAC, whereas an approximately linear increasing line was in the nonpremixed PAC. Pulsed cavity ringdown spectroscopy was also utilized to measure absolute number densities of the ground state OH(X) radicals in the Flame Zones for both fuel patterns. Results showed different number density profiles along the Flame propagation direction between the premixed and nonpremixed PAC.

  • roles of the state resolved oh a and oh x radicals in microwave plasma assisted combustion of premixed methane air an exploratory study
    Combustion and Flame, 2014
    Co-Authors: Chuji Wang, Wei Wu
    Abstract:

    Abstract We report a novel microwave plasma-assisted combustion (PAC) system that is developed as a new test platform to study roles of plasma in PAC. The system included two major components, an atmospheric pressure microwave plasma cavity and a cross-shape quartz combustor. This new PAC system allows one to study PAC using complicated yet well-controlled combinations of operating parameters, such as fuel equivalence ratio ( ϕ ), fuel mixture flow rate, plasma gas flow rate, plasma gases, symmetric or asymmetric fuel-oxidant injection patterns, with and without plasma. In this work, ignitions at the fuel (lean and rich) flammability limits at different plasma powers and fuel flow rates were investigated. The ignition curves of plasma power versus ϕ FL at the different flow rates revealed a stretched U-shape, showing clear evidences of the plasma enhancement effects on ignition and Flame stabilization, i.e. the fuel lean flammability limit ( ϕ LFL ) was extended to ϕ  = 0.2, as compared to ϕ  = 0.6 at the same combustion parameters except with no plasma. Optical emission spectroscopy (OES) showed that the combustor had three distinct reaction Zones: plasma Zone, hybrid plasma-Flame Zone, and Flame Zone; and each of the reaction Zones was well defined by its OES features. Furthermore, a detailed survey of OES of OH (A–X) conducted along the plasma jet axis ( x direction) with a spatial resolution of 0.5 mm revealed that OH(A) had a double-peak feature in its relative emission intensity curve (I ∼  x ) in the hybrid Zone where plasma-assisted ignition (PAI) started, as evidenced by a significant surge of OH(A) and by a large increase in OH rotational temperature, i.e. from 1450 K to 2400 K. Moving from the hybrid Zone to the Flame Zone, OH(A) decreased by more than four orders of magnitude. However, the electronic ground state OH(X) measured simultaneously using pulsed cavity ringdown spectroscopy around 308 nm showed that absolute number density of the OH(X) decreased by smaller than a factor of ten from the downstream of the hybrid Zone to the Flame Zone. The different changing rates of the OH(A) and OH(X) radicals from the hybrid Zone to the Flame Zone allow us to propose a hypothesis that if both the electronically excited state OH(A) and the electronic ground state OH(X) assisted the ignition and Flame stabilization processes, the role of OH(X) radicals was more dominant in the Flame stabilization but the role of OH(A) radicals was more dominant in the ignition enhancement.

  • simultaneous measurements of oh a and oh x radicals in microwave plasma jet assisted combustion of methane air mixtures around the lean burn limit using optical emission spectroscopy and cavity ringdown spectroscopy
    Journal of Physics D, 2013
    Co-Authors: Chuji Wang, Wei Wu
    Abstract:

    We report a new plasma-assisted combustion system, in which a continuous atmospheric argon microwave plasma jet is employed to enhance combustion of methane/air mixtures in different fuel equivalence ratios (?) ranging from 0.35 to 1.5. The combustor has three distinct reaction Zones along the jet axis (the combustion Flame direction): the pure plasma Zone, the hybrid plasma-Flame Zone and the combustion Flame Zone. Each of the three Zones is clearly defined by its emission spectral fingerprints. The plasma Zone was featured by strong emissions from OH and NH electronic bands and atomic lines of Ar, H? and H?. In the hybrid Zone where the plasma jet met fuel mixtures, emission spectra were dominated by OH, NH and CN transitions and by weak or no atomic transitions. In the combustion Flame Zone, only weak OH emissions were observed. Simulations of optical emission spectroscopy (OES) yielded gas kinetic temperatures to be 1175???50?K, 1450???50?K and 1865???50?K in each of the three Zones, respectively. The plasma-enhancement effect was investigated by comparing the lean-burn limits of the combustion with and without plasma. At the same fuel mixture flow rate of 1.0 standard litre per minute and plasma power of 100?W, the lean-burn limit in terms of the fuel equivalence ratio ? was extended from 0.72 without assistance of the plasma to 0.35 with assistance of the plasma. In addition to OES that was employed to characterize the excited state species including OH(A) in the three different Zones, pulsed cavity ringdown spectroscopy was utilized to measure absolute number densities of the ground state OH(X) using the OH A?X (0?0) R2 (1) line in different locations in the Flame Zone at ??=?0.51, 0.87, 1.10 and 1.45. For rich and lean combustions, significantly different OH(X) number densities and density profiles in the Flame Zone were observed. At ??=?0.51, the OH(X, V??=?0, J??=?0.5) number density increased from 2.29???1015?molecule?cm?3 at the combustor nozzle to the maximum, 3.13???1015?molecule?cm?3 at 2?mm downstream, and to the lowest detectable level of 0.12???1015 molecule cm?3 in the far downstream where optical emissions were too weak to be detected. Results from the simultaneous measurements of the electronically excited state OH(A) and the ground state OH(X) allow us to discuss the roles of OH(A) and OH(X) in the plasma-assisted ignition and the Flame stabilization, respectively.

Alireza Rahbari - One of the best experts on this subject based on the ideXlab platform.

  • the effect of lewis and damkohler numbers on the Flame propagation through micro organic dust particles
    International Journal of Thermal Sciences, 2010
    Co-Authors: Mehdi Bidabadi, Ali Haghiri, Alireza Rahbari
    Abstract:

    In this study, the role of Lewis and Damkohler numbers on the premixed Flame propagation through micro-organic dust particles is investigated. It is presumed that the fuel particles vaporize first to yield a gaseous fuel, which is oxidized in the gas phase. In order to simulate the combustion process, the Flame structure is composed of four Zones; a preheat Zone, a vaporization Zone, a reaction Zone and finally a post Flame Zone, respectively. Then the governing equations, required boundary conditions and matching conditions are applied for each Zone and the standard asymptotic method is used in order to solve these differential equations. Consequently the important parameters on the combustion phenomenon of organic dust particles such as gaseous fuel mass fraction, organic dust mass fraction and burning velocity with the various numbers of Lewis, Damkohler and the onset of vaporization are plotted in figures. This prediction has a reasonable agreement with experimental data of micro-organic dust particle combustion.