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The dilution effect on the extinction of wall diffusion flame

Nadjib Ghiti
Archives of Thermodynamics | 2014 | No 4 December | 43-54 | DOI: 10.2478/aoter-2014-0032
Keywords flame N2 Dilution wall flame infrared thermography methane
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Abstract

The dynamic process of the interaction between a turbulent jet diffusion methane flame and a lateral wall was experimentally studied. The evolution of the flame temperature field with the Nitrogen dilution of the methane jet flame was examined. The interaction between the diffusion flame and the lateral wall was investigated for different distance between the wall and the central axes of the jet flame. The dilution is found to play the central role in the flame extinction process. The flame response as the lateral wall approaches from infinity and the increasing of the dilution rate make the flame extinction more rapid than the flame without dilution, when the nitrogen dilution rate increase the flame temperature decrease.
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Authors and Affiliations

Nadjib Ghiti

Repair of Structural Steel Surface Groove by Using Flame Welding Method by Spraying Pure Iron Powder

P. Keyhany S.E. Vahdat
Archives of Foundry Engineering | 2016 | No 3 | DOI: 10.1515/afe-2016-0072
Keywords Oxyacetylene Reducing flame tensile strength
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Abstract

To improve mechanical properties and increasing useful life of metal pieces, different methods of welding are used for repairing surface

crack of metal pieces. In this research, performance of flame welding method by spraying pure iron powder evaluated for repairing surface

grooves of structural steel. First, four specimens including one control specimen and other three specimens grooved specimens in depth of

1mm and in length of 12.5mm and groove width in the sizes of 0.5, 0.75 and 1mm.were prepared then, powder melted using oxyacetylene

reducing flame and spraying iron powder in the flame path and attached to the inner surface of the groove and finally, the specimen

repaired. Results showed that after repairing surface groove, tensile strength of the repaired specimens were reached to the tensile strength

of control specimen with the margin of 2.5%.

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Authors and Affiliations

P. Keyhany
S.E. Vahdat

Investigation on effect of air velocity in turbulent non-premixed flames

Zafar Namazian Heidar Hashemi Farideh Namazian
Archive of Mechanical Engineering | 2016 | vol. 63 | No 3 | 355-366 | DOI: 10.1515/meceng-2016-0020
Keywords turbulent flame methane-air non-premixed length of flame flame temperature
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Abstract

In this study, the turbulent non-premixed methane-air flame is simulated to determine the effect of air velocity on the length of flame, temperature distribution and mole fraction of species. The computational fluid dynamics (CFD) technique is used to perform this simulation. To solve the turbulence flow, k-ε model is used. In contrast to the previous works, in this study, in each one of simulations the properties of materials are taken variable and then the results are compared. The results show that at a certain flow rate of fuel, by increasing the air velocity, similar to when the properties are constant, the width of the flame becomes thinner and the maximum temperature is higher; the penetration of oxygen into the fuel as well as fuel consumption is also increased. It is noteworthy that most of the pollutants produced are NOx, which are strongly temperature dependent. The amount of these pollutants rises when the temperature is increased. As a solution, decreasing the air velocity can decrease the amount of these pollutants. Finally, comparing the result of this study and the other work, which considers constant properties, shows that the variable properties assumption leads to obtaining more exact solution but the trends of both results are similar.

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Authors and Affiliations

Zafar Namazian
Heidar Hashemi
Farideh Namazian

An overview of the (eco)toxicological effects of flame retardants emerging in water and sediment

Adriana M. Dowbysz Mariola Samsonowicz Bożena Kukfisz
Journal of Water and Land Development | 2023 | No 59 | 44-49 | DOI: 10.24425/jwld.2023.147227
Keywords organophosphorus flame retardants novel brominated flame retardants ecotoxicity water sediment
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Abstract

Flame retardants (FRs) that have an adverse effect on human and the environment have been subject to regulation since 1972. However, FRs emerging as a replacement, are not proving to be fully environmentally safe. Water and sediment contamination by FRs, including organophosphorus (OPFRs) and novel brominated (NBFRs) ones, is a matter of major concern. Due to their common usage, many release sources, and relatively high mobility, they pose a threat to aquatic organisms and ecosystems. This review summarises studies on the OPFRs’, and NBFRs’ simultaneous occurrence in water and corresponding sediment. The main sources of occurrence and routes of entry of FRs into the environment are presented. The newest reports on the ecotoxicity of selected FRs had been summarised in order to bring the matter to attention. The research revealed that although great efforts had been made to study the occurrence of OPFRs and NBFRs in water and sediment separately, there is a lack of research on their occurrence in both media in the same area. Although major efforts have been made to study the ecotoxicity of OPFRs, there are some deficiencies for the NBFRs. Considering their relatively high ecotoxicity, further studies should be conducted on joint ecotoxicity, which may cause synergistic or antagonistic effects.
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Authors and Affiliations

Adriana M. Dowbysz
1
ORCID: ORCID
Mariola Samsonowicz
1
ORCID: ORCID
Bożena Kukfisz
2
ORCID: ORCID
  1. Bialystok University of Technology, Department of Chemistry, Biology and Biotechnology, 45E Wiejska St, 15-351, Bialystok, Poland
  2. Fire University, Institute of Safety Engineering, Warsaw, Poland

Numerical study of laminar non-premixed biogas-air flames behind backward facing steps

Alagani Harish Vasudevan Raghavan
Archive of Mechanical Engineering | 2022 | vol. 69 | No 2 | 221-244 | DOI: 10.24425/ame.2022.140413
Keywords biogas non-premixed flames backward facing step flame stability detailed kinetics
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Abstract

Biogas, a renewable fuel, has low operational stability range in burners due to its inherent carbon-dioxide content. In cross-flow configuration, biogas is injected from a horizontal injector and air is supplied in an orthogonal direction to the fuel flow. To increase the stable operating regime, backward facing steps are used. Systematic numerical simulations of these flames are reported here. The comprehensive numerical model incorporates a chemical kinetic mechanism having 25 species and 121 elementary reactions, multicomponent diffusion, variable thermo-physical properties, and optically thin approximation based volumetric radiation model. The model is able to predict different stable flame types formed behind the step under different air and fuel flow rates, comparable to experimental predictions. Predicted flow, species, and temperature fields in the flames within the stable operating regime, revealing their anchoring positions relative to the rear face of the backward facing step, which are difficult to be measured experimentally, have been presented in detail. Resultant flow field behind a backward facing step under chemically reactive condition is compared against the flow fields under isothermal and non-reactive conditions to reveal the significant change the chemical reaction produces. Effects of step height and step location relative to the fuel injector are also presented.
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Authors and Affiliations

Alagani Harish
1
ORCID: ORCID
Vasudevan Raghavan
1
  1. Indian Institute of Technology Madras, Chennai, India

Simulation Studies on the Influence of Other Combustible Gases on the Characteristics of Methane Explosions at Constant Volume and High Temperature

Zhenmin Luo Litao Liu Shuaishuai Gao Tao Wang Bin Su Lei Wang Yong Yang Xiufang Li
Archives of Mining Sciences | 2021 | vol. 66 | No 2 | 279-295 | DOI: 10.24425/ams.2021.137462
Keywords Constant volume Volume fraction of combustible gas Initial temperature adiabatic flame temperature Maximum explosion pressure
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Abstract

Gas explosions are major disasters in coal mining, and they typically cause a large number of deaths, injuries and property losses. An appropriate understanding of the effects of combustible gases on the characteristics of methane explosions is essential to prevent and control methane explosions. FLACS software was used to simulate an explosion of a mixture of CH4 and combustible gases (C2H4, C2H6, H2, and CO) at various mixing concentrations and different temperatures (25, 60, 100, 140 and 180℃). After adding combustible gases to methane at a constant volume and atmospheric pressure, the adiabatic flame temperature linearly increases as the initial temperature increases. Under stoichiometric conditions (9.5% CH4-air mixture), the addition of C2H4 and C2H6 has a greater effect on the adiabatic flame temperature of methane than H2 and CO at different initial temperatures. Under the fuel-lean CH4-air mixture (7% CH4-air mixture) and fuel-rich mixture (11% CH4-air mixture), the addition of H2 and CO has a greater effect on the adiabatic flame temperature of methane. In contrast, the addition of combustible gases negatively affected the maximum explosion pressure of the CH4-air mixture, exhibiting a linearly decreasing trend with increasing initial temperature. As the volume fraction of the mixed gas increases, the adiabatic flame temperature and maximum explosion pressure of the stoichiometric conditions increase. In contrast, under the fuel-rich mixture, the combustible gas slightly lowered the adiabatic flame temperature and the maximum explosion pressure. When the initial temperature was 140℃, the fuel consumption time was approximately 8-10 ms earlier than that at the initial temperature of 25℃. When the volume fraction of the combustible gas was 2.0%, the consumption time of fuel reduced by approximately 10 ms compared with that observed when the volume fraction of flammable gas was 0.4%.
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Authors and Affiliations

Zhenmin Luo
1 2
ORCID: ORCID
Litao Liu
1 2
ORCID: ORCID
Shuaishuai Gao
1 2
ORCID: ORCID
Tao Wang
1 2 3
ORCID: ORCID
Bin Su
1 2
ORCID: ORCID
Lei Wang
1 2
ORCID: ORCID
Yong Yang
4 2
ORCID: ORCID
Xiufang Li
4
ORCID: ORCID
  1. Xi’an University of Science and Technology, School of Safety Science & Engineering, 58, Yanta Mid. Rd., Xi’an, 710054, Shaanxi, PR China
  2. Shaanxi Key Laboratory of Prevention and Control of Coal Fire, 58, Yanta Mid. Rd, Xi’an, 710054, Shaanxi, PR China
  3. Xi’an University of Science and Technology, Postdoctoral Program, 58, Yanta Mid. Rd., Xi’an 710054, Shaanxi, PR China
  4. Xi’an University of Science and Technology, School of Safety Science & Engineering, 58, Yanta Mid. Rd., Xi’an, 710054, Shaanxi, PR

Assessment of Trace Element Content in Products and Wastes of Coal Treatments from the Upper-Silesian Basin

Krystyna Srogi Mariusz Minkina
Archives of Environmental Protection | 2005 | vol. 31 | No 1 | 95-106
Keywords trace elements coal products and wastes microwave digestion flame and electrothermalatomic absorption spectrometry adsorptive and anodic stripping voltammetry
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Abstract

The aim of the study was to estimate the content of trace elements: zinc, cadmium, lead, molybdenum and nickel in products and wastes of coal treatment from Upper-Silesian Basin. Two analytical methods were applied: atomic absorption spectrometry (FAAS, ETAAS) and anodic (ASY) and adsorptive stripping voltammetry (AdSY). ASY is used to determine zinc, cadmium and lead; AdSY molybdenum and nickel, and FAAS and ETAAS to determine all elements. In the case of Zn, Ni, Mo, Pb and Cd determined by FAAS (ETAAS) the concentrations were practically the same as those obtained by ASY or AdSY.
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Authors and Affiliations

Krystyna Srogi
Mariusz Minkina

Commercial Penta-BDE Mixtures in Dust Samples from Indoor Environments in Lublin, Poland - a Case Study

Amelia Staszowska Bernard Połednik Marzenna R. Dudzińska Jacek Czerwiński
Archives of Environmental Protection | 2008 | vol. 34 | No 3 | 239-247
Keywords Flame retardants polybrominated diphenyl ethers (PBOEs) Penta-BOE dust indoor air quality
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Abstract

Levels and distribution of selected polybrorninated diphenyl ether congeners in dust samples taken from different indoor environments in Lublin, South-Eastern Poland, are reported. The most abundant congeners, found in the majority of sampling sites, were BOE 47, 100 and 28, respectively. The highest levels of examined congeners were observed in dust samples taken from a computer repair facility and labs. BOE 47, 99 and 100, occurring at highest levels and having the greatest contribution confirm that in Polish indoor environments polymer products contain Penta - BOE technical mixture.
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Authors and Affiliations

Amelia Staszowska
Bernard Połednik
Marzenna R. Dudzińska
Jacek Czerwiński

Influence of Flame Retardant and Processing Conditions on Selected Properties of Mouldings Made of ABS

M. Trzaskalska
Archives of Metallurgy and Materials | 2022 | vol. 67 | No 4 | 1381-1386 | DOI: 10.24425/amm.2022.141065
Keywords injection moulding ABS PS TiO2 flame retardant mechanical properties
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Abstract

Thanks to dyeing of polymers, the possibilities of their use are constantly increasing. It is equally important to use additives that will have several functions. A perfect example is titanium dioxide used as an optical brightener and a flame retardant at the same time. Mostly it is used in the form of a powder. However, there are no studies where TiO2 is used as a colourbatch based on the different polymer matrix.
The aim of the work was to investigate the effect of titanium white in the form of colourbatch on the flammability and selected properties of mouldings produced in various processing conditions. Colourbatch based on PS matrix, was used in the research. The variable processing parameters were: injection temperature Tw, volume flow rate Vw, residence time and the addition of a colourbatch. On the basis of the measurements, it was found that the processing conditions and the addition of the colourbatch have low effect on the hardness of the mouldings, which was in the range from 75.59o Sh D (Shore type D) to 81.95o Sh D. It was also noted that the addition of colourbatch with TiO2 and increasing injection temperature reduces impact strength even by several dozen percent. Moreover, it was found that use of TiO2 causes a delay in the ignitability of the samples in selected cases. It is difficult to determine whether the variable processing conditions or the addition of TiO2 on the PS matrix have a greater impact on the ignitability of the moulded parts.
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Authors and Affiliations

M. Trzaskalska
1
ORCID: ORCID
  1. Czestochowa University of Technology, Faculty of Mechanical Engineering and Computer Science, Department of Technology and Automation, 21 Armii Krajowej Av., 42-201 Czestochowa, Poland

Numerical analysis of structure, stability and entropy generation in biogas coflow diffusion flames

R. Nivethana Kumar S. Muthu Kumaran Vasudevan Raghavan
Archive of Mechanical Engineering | 2022 | vol. 69 | No 1 | 99-128 | DOI: 10.24425/ame.2021.139648
Keywords biogas flame stability entropy generation coflow air hydrogen injection preheated reactants
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Abstract

Biogas is a gaseous biofuel predominantly composed of methane and carbon-dioxide. Stability of biogas flames strongly depend upon the amount of carbon-dioxide present in biogas, which varies with the source of biomass and reactor. In this paper, a comprehensive study on the stability and flame characteristics of coflow biogas diffusion flames is reported. Numerical simulations are carried out using reactive flow module in OpenFOAM, incorporated with variable thermophysical properties, Fick’s and Soret diffusion, and short chemical kinetics mechanism. Effects of carbon-dioxide content in the biogas, temperatures of the fuel or coflowing air streams (preheated reactant) and hydrogen addition to fuel or air streams are analyzed. Entropy generation in these flames is also predicted. Results show that the flame temperature increases with the degree of preheat of reactants and the flames show better stability with the preheated air stream. Preheating the air contributes to increased flame stability and also to a significant decrease in entropy generation. Hydrogen addition, contributing to the same power rating, is seen to be relatively more effective in increasing the flame stability when added to the fuel stream. Results in terms of flow, temperature, species and entropy fields, are used to describe the stability and flame characteristics.
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Authors and Affiliations

R. Nivethana Kumar
1
S. Muthu Kumaran
1
Vasudevan Raghavan
1
  1. Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai – 600036, India

Process Design for Size-Controlled Flame Spray Synthesis of Li4Ti5O12 and Electrochemical Performance

Oliver Waser Oliver Brenner Arto J. Groehn Sotiris E. Pratsinis
Chemical and Process Engineering | 2017 | vol. 38 | No 1 | 51-66 | DOI: 10.1515/cpe-2017-0005
Keywords Li-ion battery Li4Ti5O12 size control residence time distribution computational fluid dynamics flame synthesis of electroceramics
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Abstract

Inexpensive synthesis of electroceramic materials is required for efficient energy storage. Here the design of a scalable process, flame spray pyrolysis (FSP), for synthesis of size-controlled nanomaterials is investigated focusing on understanding the role of air entrainment (AE) during their aerosol synthesis with emphasis on battery materials. The AE into the enclosed FSP reactor is analysed quantitatively by computational fluid dynamics (CFD) and calculated temperatures are verified by Fourier transform infrared spectroscopy (FTIR). Various Li4Ti5O12 (LTO) particle compositions are made and characterized by N2 adsorption, electron microscopy and X-ray diffraction while the electrochemical performance of LTO is tested at various charging rates. Increasing AE decreases recirculation in the enclosing tube leading to lower reactor temperatures and particle concentrations by air dilution as well as shorter and narrower residence time distributions. As a result, particle growth by coagulation - coalescence decreases leading to smaller primary particles that are mostly pure LTO exhibiting high C-rate performance with more than 120 mAh/g galvanostatic specific charge at 40C, outperforming commercial LTO. The effect of AE on FSP-made particle characteristics is demonstrated also in combustion synthesis of LiFePO4 and ZrO2.

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Authors and Affiliations

Oliver Waser
Oliver Brenner
Arto J. Groehn
Sotiris E. Pratsinis

Use of Microwave-Assisted Digestion for Determination of Element Contents in Environmental Materials by ICP-AES and FAAS

Krystyna Srogi
Archives of Environmental Protection | 2006 | vol. 32 | No 1 | 89-104
Keywords Microwave digestion plant materials coal fly ash soil Flame Atomic Absorption Spectroscopy(FAAS) Inductively Coupled Plasma Atomic Emission Spectrometry ([CP-AES) trace clementsdetermination
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Abstract

The methods arc described for determinations of Al, Fe, Ca, Mg, Ba, Cr, Mn, Ni, Cu, Zn, Pb, Cd, V and Sr in botanical, coal fly ash and soil samples by flame atomic absorption spectrometry (FAAS), and inductively coupled plasma atomic emission spectrometry (!CP-AES). Special attention has been paid to sample preparation, an important stage at which a sample is explored to contaminants. Results of the analysis of all samples arc discussed.
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Authors and Affiliations

Krystyna Srogi

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