An asymptotic analysis for detailed mathematical modeling of counter-flow non-premixed multi-zone laminar flames fueled by lycopodium particles

2019 ◽  
Vol 30 (4) ◽  
pp. 2137-2168 ◽  
Author(s):  
Mehdi Bidabadi ◽  
Sadegh Sadeghi ◽  
Pedram Panahifar ◽  
Davood Toghraie ◽  
Alireza Rahbari
Keyword(s):  
Mathematical Modeling ◽  
Asymptotic Method ◽  
Flame Temperature ◽  
Laminar Flames ◽  
Counter Flow ◽  
Content Type ◽  
Front Position ◽  
Mass Fractions ◽  
Premixed Laminar ◽  
Fuel Particles

Purpose This study aims to present a basic mathematical model for investigating the structure of counter-flow non-premixed laminar flames propagating through uniformly-distributed organic fuel particles considering preheat, drying, vaporization, reaction and oxidizer zones. Design/methodology/approach Lycopodium particles and air are taken as biofuel and oxidizer, respectively. Dimensionalized and non-dimensionalized forms of mass and energy conservation equations are derived for each zone taking into account proper boundary and jump conditions. Subsequently, to solve the governing equations, an asymptotic method is used. For validation purpose, results achieved from the present analysis are compared with reliable data reported in the literature under certain conditions. Findings With regard to the comparisons, although different complex non-homogeneous differential equations are solved in this paper, acceptable agreements are observed. Finally, the impacts of significant parameters including fuel and oxidizer Lewis numbers, equivalence ratio, mass particle concentration, fuel and oxidizer mass fractions and lycopodium initial temperature on the flame temperature, flame front position and flow strain rate are elaborately explained. Originality/value An asymptotic method for mathematical modeling of counter-flow non-premixed multi-zone laminar flames propagating through lycopodium particles.

Mathematical modeling of the production of magnetic nanoparticles through counter-flow non-premixed combustion for biomedical applications

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shahin Akbari ◽  
Nima Hasanvand ◽  
Sadegh Sadeghi ◽  
Mehdi Bidabadi ◽  
Qingang Xiong
Keyword(s):  
Magnetic Nanoparticles ◽  
Large Scale ◽  
Flame Temperature ◽  
Combustion Process ◽  
Premixed Combustion ◽  
Counter Flow ◽  
Content Type ◽  
Thermophoretic Force ◽  
Mass Fractions ◽  
Carrier Gases

Purpose The widespread usage of magnetic nanoparticles (MNPs) requires their efficient synthesis during combustion process. This study aims to present a mathematical model for the oxidation of MNPs in a counter-flow non-premixed combustion system to produce MNPs, where the key sub-processes during the oxidation reaction are involved. Design/methodology/approach To accurately describe structure of flame and determine distributions of temperature and mass fractions of both reactants and products, equations of energy and mass conservations were solved based on the prevailing assumptions that three regions, i.e. preheating, reaction and oxidizer zones exist. Findings The numerical simulation was first validated against experimental data and characteristics of the combustion process are discussed. Eventually, the influences of crucial parameters such as reactant Lewis numbers, strain rate ratio, particle size, inert gas and thermophoretic force on structure of flame and combustion behavior were examined. The results show that maximum flame temperature can achieve 2,205 K. Replacing nitrogen with argon and helium as carrier gases can increase flame temperature by about 27% and 34%, respectively. Additionally, maximum absolute thermophoretic force was found at approximately 9.6 × 10–8 N. Originality/value To the best of authors’ knowledge, this is the first time to numerically model the preparation of MNPs in a counter-flow non-premixed combustion configuration, which can guide large-scale experimental work in a more effective way.

scholarly journals Mathematical Modeling of Non-Premixed Laminar Flow Flames Fed with Biofuel in Counter-Flow Arrangement Considering Porosity and Thermophoresis Effects: An Asymptotic Approach

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2945 ◽  
Author(s):  
Mehdi Bidabadi ◽  
Peyman Ghashghaei Nejad ◽  
Hamed Rasam ◽  
Sadegh Sadeghi ◽  
Bahman Shabani
Keyword(s):  
Laminar Flow ◽  
Solid Phase ◽  
Medical Systems ◽  
Safe Operation ◽  
Counter Flow ◽  
Thermophoretic Force ◽  
Mass Fractions ◽  
Premixed Laminar ◽  
Organic Particles ◽  
Flame Sheet

Due to the safe operation and stability of non-premixed combustion, it can widely be utilized in different engineering power and medical systems. The current paper suggests a mathematical asymptotic technique to describe non-premixed laminar flow flames formed in organic particles in a counter-flow configuration. In this investigation, fuel and oxidizer enter the combustor from opposite sides separately and multiple zones including preheating, vaporization, flame and post-flame zones were considered. Micro-sized lycopodium particles and air were respectively applied as a biofuel and an oxidizer. Dimensionalized and non-dimensionalized mass and energy conservation equations were determined for the zones and solved by Mathematica and Matlab software by applying proper boundary and jump conditions. Since lycopodium particles have numerous spores, the porosity of the particles was involved in the equations. Further, significant parameters such as lycopodium vaporization rate and thermophoretic force corresponding to the lycopodium particles in the solid phase were examined. The temperature distribution, flame sheet position, fuel and oxidizer mass fractions, equivalence ratio and flow strain rate were evaluated for the counter-flow non-premixed flames. Ultimately, the thermophoretic force caused by the temperature gradient at different positions was computed for several values of porosity, fuel and oxidizer Lewis numbers.

IMPLEMENTATION OF THE FLAMELET-GENERATED-MANIFOLD FOR PREMIXED LAMINAR FLAMES WITH HEAT LOSS

2018 ◽  
Author(s):  
Leonardo Donatti ◽  
Andre Carlos Contini ◽  
Cristian Alex Hoerlle ◽  
Leonardo Zimmer ◽  
Lisandro Maders ◽  
...  
Keyword(s):  
Heat Loss ◽  
Laminar Flames ◽  
Flamelet Generated Manifold ◽  
Premixed Laminar Flames ◽  
Premixed Laminar

Economic thought in the 17th and 18th centuries: a linguistic approach

2015 ◽  
Vol 23 (3) ◽  
pp. 260-270
Author(s):  
Iara Vigo de Lima
Keyword(s):  
Economic Thought ◽  
Point Of View ◽  
Content Type ◽  
Front Position ◽  
History Of ◽  
Epistemological Model ◽  
Theory Of Language ◽  
Theory Of Value ◽  
Linguistic Approach ◽  
Practical Implications

Purpose – The purpose of this paper is to analyse Michel Foucault’s new epistemological model regarding an analogy between the theory of language and economic thought in the seventeenth and eighteenth centuries. Design/methodology/approach – Through the scrutiny of language, Foucault intended to demonstrate that some analogies, among different branches of knowledge (interdiscursive practice), allow us to apprehend the underlying configuration of thought regarding ontological and epistemological conditions that have historically determined knowledge. He draws a parallel between four theoretical segments borrowed from general grammar (Attribution, Articulation, Designation and Derivation) and economic thought on wealth. Findings – One of the most remarkable propositions of this approach is that the theory of language and economic thought were epistemologically isomorphic in that context. What the theory of language stated in relation to “attribution” and “articulation” corresponded to the “theory of value” in economic thought. What grammar investigated regarding “designation” and “derivation” was analogous to the “theory of money and trade” in economic thought. The relationships that were – directly and diagonally – identified between and among them led to the conclusion that there was ‘a circular and surface causality’ in economic thought insofar as “circulation” preceded “production”. It was “superficial” because it could not find an explanation for the cause of “wealth”, which was only possible when “production” was placed in the front position of theories. Practical implications – Such an epistemological point of view can inspire other studies in the history of economic thought. Originality/value – This paper offers a perspective on how to think about the history of ontological and epistemological conditions of economic thought.

PAHs formation simulation in the premixed laminar flames of TRF with alcohol addition using a semi-detailed combustion mechanism

Fuel ◽  
2015 ◽  
Vol 155 ◽  
pp. 44-54 ◽  
Author(s):  
Guorui Jia ◽  
Mingfa Yao ◽  
Haifeng Liu ◽  
Peng Zhang ◽  
Beiling Chen ◽  
...  
Keyword(s):  
Laminar Flames ◽  
Combustion Mechanism ◽  
Premixed Laminar Flames ◽  
Premixed Laminar

The Effect of Lewis Number on Instantaneous Flamelet Speed and Position Statistics in Counter-Flow Flames With Increasing Turbulence

2017 ◽  
Author(s):  
Sean D. Salusbury ◽  
Ehsan Abbasi-Atibeh ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Flame Front ◽  
Turbulence Intensity ◽  
High Speed ◽  
Rayleigh Scattering ◽  
Turbulent Flame ◽  
Lewis Number ◽  
Turbulent Flames ◽  
Flame Speed ◽  
Laminar Flames ◽  
Counter Flow

Differential diffusion effects in premixed combustion are studied in a counter-flow flame experiment for fuel-lean flames of three fuels with different Lewis numbers: methane, propane, and hydrogen. Previous studies of stretched laminar flames show that a maximum reference flame speed is observed for mixtures with Le ≳ 1 at lower flame-stretch values than at extinction, while the reference flame speed for Le ≪ 1 increases until extinction occurs when the flame is constrained by the stagnation point. In this work, counter-flow flame experiments are performed for these same mixtures, building upon the laminar results by using variable high-blockage turbulence-generating plates to generate turbulence intensities from the near-laminar u′/SLo=1 to the maximum u′/SLo achievable for each mixture, on the order of u′/SLo=10. Local, instantaneous reference flamelet speeds within the turbulent flame are extracted from high-speed PIV measurements. Instantaneous flame front positions are measured by Rayleigh scattering. The probability-density functions (PDFs) of instantaneous reference flamelet speeds for the Le ≳ 1 mixtures illustrate that the flamelet speeds are increasing with increasing turbulence intensity. However, at the highest turbulence intensities measured in these experiments, the probability seems to drop off at a velocity that matches experimentally-measured maximum reference flame speeds in previous work. In contrast, in the Le ≪ 1 turbulent flames, the most-probable instantaneous reference flamelet speed increases with increasing turbulence intensity and can, significantly, exceed the maximum reference flame speed measured in counter-flow laminar flames at extinction, with the PDF remaining near symmetric for the highest turbulence intensities. These results are reinforced by instantaneous flame position measurements. Flame-front location PDFs show the most probable flame location is linked both to the bulk flow velocity and to the instantaneous velocity PDFs. Furthermore, hydrogen flame-location PDFs are recognizably skewed upstream as u′/SLo increases, indicating a tendency for the Le ≪ 1 flame brush to propagate farther into the unburned reactants against a steepening average velocity gradient.

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