检索结果-南通市图书馆

Journal of Central South University 2017年第1期24卷 81-89页

作者： mehdi bidabadi Alireza Khoeini Poorfar Combustion Research Laboratory School of Mechanical EngineeringIran University of Science and Technology(IUST)Narmak16846-13114TehranIran

In this research combustion of aluminum dust particles in a quiescent medium with spatially discrete sources distributed in a random way was studied by a numerical approach.A new thermal model was generated to estimate flame propagation speed in a lean/rich reaction *** speed for different particle diameters and the effects of various oxidizers such as carbon dioxide and oxygen on flame speed were *** was considered the inert *** addition,the quenching distance and the minimum ignition energy(MIE) were studied as a function of dust *** burning time models for aluminum were employed and their results were compared with each *** model was based on conduction heat transfer mechanism using the heat point source *** combustion of single-particle was first studied and the solution was *** the dust combustion was investigated using the superposition principle to include the effects of surrounding *** is found that larger particles have higher values of quenching distance in comparison with smaller particles in an assumed dust *** the increase of dust concentration the value of MIE would be decreased for an assumed particle *** random discrete heat sources method,the obtained results of random distribution of fuel particles in space provide closer and realistic predictions of the combustion physics of aluminum dust flame as compared with the experimental findings.

关键词： flame propagation speed random particle distribution quenching distance random discrete combustion aluminum

Modeling multi regional counter flow combustion of lycopodium dust cloud with considering radiative heat loss

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2017年第11期24卷 2638-2648页

作者： bidabadi mehdi Ebrahimi Farzaneh Bordbar Vahid School of Mechanical Engineering Department of Energy ConversionCombustion Research LaboratoryIran University of Science and Technology(IUST)Tehran ***Iran

In this work, an analytical model is presented to simulate the combustion process of organic dust with considering radiative heat loss effect in counterflow configuration. A thermal model has been generated to estimate the flame propagation speed in various dust concentrations. The structure of premixed flame in a symmetric configuration, containing uniformly distributed volatile fuel particles, with nonunity Lewis number is examined with strain rate issue. The flame structure is divided into six zones: first heating, drying, second heating, volatile evaporation, reaction and post-flame zones. At first, the governing equations of lycopodium combustion dust particles are written for each zone. Finally, boundary conditions and matching conditions are applied for each zone in order to solve the differential equations. The purpose of this article is to analyze radiation heat transfer on lycopodium flame propagation dust particles and characteristics to check the effect of parameters on combustion.

关键词： radiative heat counterflow lycopodium analytical model

Pyrolysis and combustion kinetics of lycopodium particles in thermogravimetric analysis

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2015年第9期22卷 3409-3417页

作者： Seyed Alireza Mostafavi Sadjad Salavati Hossein Beidaghy Dizaji mehdi bidabadi Department of Mechanical Engineering Faculty of Engineering Arak University School of Mechanical Engineering Department of Energy Conversion Combustion Research Laboratory Iran University of Science and Technology

Biomass is a kind of renewable energy which is used increasingly in different types of combustion systems or in the production of fuels like bio-oil. Lycopodium is a cellulosic particle, with good combustion properties, of which microscopic images show that these particles have spherical shapes with identical diameters of 31 μm. The measured density of these particles is 1.0779 g/cm2. Lycopodium particles contain 64.06% carbon, 25.56% oxygen, 8.55% hydrogen and 1.83% nitrogen, and no sulfur. Thermogravimetric analysis in the nitrogen environment indicates that the maximum of particle mass reduction occurs in the temperature range of 250-550 ℃ where the maximum mass reduction in the DTG diagrams also occurs in. In the oxygen environment, an additional peak can also be observed in the temperature range of 500-600 ℃, which points to solid phase combustion and ignition temperature of lycopodium particles. The kinetics of reactions is determined by curve fitting and minimization of error.

关键词： lycopodium dust particles thermogravimetric analysis pyrolysis combustion ignition temperature chemical kinetics

Micro-organic dust combustion considering particles thermal resistance

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2015年第7期22卷 2833-2840页

作者： Mohammadamin Soltaninejad Farzad Faraji Dizaji Hossein Beidaghy Dizaji mehdi bidabadi School of Mechanical Engineering Department of Energy Conversion Combustion Research LaboratoryIran University of Science and Technology School of Engineering The University of Vermont Young Researchers and Elite Club Tabriz Branch Islamic Azad University

Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.

关键词： micro-organic dust Biot number particles thermal resistance flame temperature burning velocity

Investigation of effective dimensionless numbers on initiation of instability in combustion of moisty organic dust

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2014年第1期21卷 326-337页

作者： mehdi bidabadi Farzad Faraji Dizaji Hossein Beidaghy Dizaji Moslem Safari Ghahsareh School of Mechanical Engineering Department of Energy ConversionCombustion Research LaboratoryIran University of Science and Technology Young Researchers and Elite Club Tabriz BranchIslamic Azad University

In this work, the effect of various effective dimensionless numbers and moisture contents on initiation of instability in combustion of moisty organic dust is calculated. To have reliable model, effect of thermal radiation is taken into account. One- dimensional flame structure is divided into three zones： preheat zone, reaction zone and post-flame zone. To investigate pulsating characteristics of flame, governing equations are rewritten in dimensionless space-time （（, r/, ~） coordinates. By solving these newly achieved governing equations and combining them, which is completely discussed in body of article, a new expression is obtained. By solving this equation, it is possible to predict initiation of instability in organic dust flame. According to the obtained results by increasing Lewis number, threshold of instability happens sooner. On the other hand, pulsating is postponed by increasing Damk6hler number, pyrolysis temperature or moisture content. Also, by considering thermal radiation effect, burning velocity predicted by our model is closer to experimental results.

关键词： instability Lewis number Damk6hler number pyrolysis temperature moisture content organic dust

An analytical model for pyrolysis of a single biomass particle

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2015年第1期22卷 350-359页

作者： mehdi bidabadi Mohammad Rastegar Moghaddam Seyed Alireza Mostafavi Farzad Faraji Dizaji Hossein Beidaghy Dizaji School of Mechanical Engineering Department of Energy Conversion Combustion Research LaboratoryIran University of Science and Technology Department of Mechanical Engineering Faculty of Engineering Arak University School of Engineering the University of Vermont 33 Colchecter Avenue Young Researchers and Elite Club Tabriz Branch Islamic Azad University

Decreasing in emissions of greenhouse gases to confront the global warming needs to replace fossil fuels as the main doer of the world climate changes by renewable and clean fuels produced from biomass like wood waste which is neutral on the amount of CO2. An analytical and engineering model for pyrolysis process of a single biomass particle has been presented. Using a two-stage semi global kinetic model which includes both primary and secondary reactions, the effects of parameters like shape and size of particle as well as porosity on the particle temperature profile and product yields have been investigated. Comparison of the obtained results with experimental data shows that our results are in a reasonable agreement with previous researchers' works. Finally, a sensitivity analysis is done to determine the importance of each parameter on pyrolysis of a single biomass particle which is affected by many constant parameters.

关键词： biomass pyrolysis analytical model single particle sensitivity analysis

Analytical Model for Predicting the Heat Loss Effect on the Pyrolysis of Biomass Particles

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2013年第10期21卷 1114-1120页

作者： Alireza Rahbari Fatemeh Ebrahiminasab mehdi bidabadi Department of Mechanical Engineering Shahid Raj aee Teacher Training University (S RTTU) Tehran lran Deigartment of Mechanical Englneering. Iran University of Science and Technology Combustion Research LaboratoryNarmak Tehran Iran

This paper presents the combined influence of heat-loss and radiation on the pyrolysis of biomass particles by considering the structure of one-dimensional, laminar and steady state flame propagation in uniformly premixed wood particles. The assumed flame structure consists of a broad preheat-vaporization zone where the rate of gas-phase chemical reaction is small, a thin reaction zone composed of three regions: gas, tar and char combustion where convection and the vaporization rate of the fuel particles are small, and a broad convection zone. The analysis is performed in the asymptotic limit, where the value of the characteristic Zeldovich number is large and the equivalence ratio is larger than unity(i.e.u≥1). The principal attention is made on the determination of a non-linear burning velocity correlation. Consequently, the impacts of radiation, heat loss and particle size as the determining factors on the flame temperature and burning velocity of biomass particles are declared in this research.

关键词： analytical model heat loss radiation particle size pyrolysis tlame temperature burning velocity

Analytical investigation of temperature of a single micron sized iron particle during combustion

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2020年第3期27卷 951-962页

作者： Peyman MAGHSOUDI mehdi bidabadi Seyed Amir Hossein MADANI Abolfazl AFZALABADI Department of Energy Conversion School of Mechanical EngineeringIran University of Science and Technology(IUST)Narmak16846-13114TehranIran

The present study deals with analytical investigation of temperature of a single burning iron *** mathematical methods including AGM(Akbari-Ganji’s method),CM(Collocation method)and GM(Galerkin Method)are applied to solving non-linear differential governing equation and effectiveness of these methods is examined as *** further investigation,forth order Runge-Kutta approach,a numerical method,is used to validate the obtained analytical *** the present study,the developed mathematical model takes into account the effects of thermal radiation,convective heat transfer and particle density variations during combustion *** to particles’small size and high thermal conductivity,the system is assumed to be lumped in which the particle temperature does not change within the body and all of its regions are at the same *** temperature distributions obtained by analytical methods have satisfactory agreement with numerical ***,the results indicate that AGM is a more appropriate method than GM and CM due to its lower mean relative error and less run time.

关键词： iron particle combustion analytical solutions thermal radiation convective heat transfer

Responses of Grafted Watermelon onto Cucurbita pepo Tiana F1 Hybrid to Boron Nutritional Disorders

在线全文

学校读者我要写书评

暂无评论

Horticultural Plant Journal 2019年第5期5卷 213-220页

作者： Shirani bidabadi Siamak Sabbatini Paolo Department of Horticulture College of AgricultureIsfahan University of TechnologyIsfahan84156-83111Iran Department of Horticulture Michigan State UniversityEast LansingMI48824USA

Sensitivity to boron stress in growing media during the early seedlings stage could severely inhibit watermelon growth and development. The aim of this study was to test if watermelon(Citrullus lanatus cv. Mahbubi) performance can be improved under different boron concentrations(0, 46.31 and 935.11 μmol·L-1 H3BO3) by grafting watermelon plants onto Cucurbita pepo Tiana F1 hybrid rootstock. Shoot dry weight of grafted watermelon was significantly higher than those of non-grafted plants under boron stress conditions(0 and 935.11 μmol·L-1). Boron concentration of the aerial organs of the grafted plants was higher than in the non-grafted ones when treated with 0 μmol·L-1 H3BO3. However, with the application of boron(935.11 μmol·L-1 H3BO3), the aerial organs of grafted plants accumulated lower boron than non-grafted ones. The Cucurbita pepo rootstock also improved the absorption of several other nutrients and leaf chlorophyll content and the Fv/Fmratio was also increased at high boron root concentration. Higher activities of several antioxidant enzymes such as catalase(CAT), superoxide dismutase(SOD) and peroxidase(POX) in grafted watermelons were associated with a significant reduction in H2O2 and malondialdehyde(MDA) generation when compared with those of non-grafted plants under boron stress conditions(0 and 935.11 μmol·L-1 H3BO3). Grafted plants reported improved growth, nutrient uptake and several other physiological parameters when compared to non-grafted watermelon plants under boron stress conditions.

关键词： Citrullus lanatus Cucurbita pepo lipid peroxidation oxidative stress rootstock

Development of a radiographic method for measuring the discrete spectrum of the electron beam from a plasma focus device

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2017年第7期19卷 26-33页

作者： Neda SHAMSIAN Babak SHIRANI bidabadi Hosein PIRJAMADI Department of Nuclear Engineering Faculty of Advanced Sciences and Technologies University of Isfahan

An indirect method is proposed for measuring the relative energy spectrum of the pulsed electron beam of a plasma focus device. The Bremsstrahlung x-ray, generated by the collision of electrons against the anode surface, was measured behind lead filters with various thicknesses using a radiographic film system. A matrix equation was considered in order to explain the relation between the x-ray dose and the spectral amplitudes of the electron beam. The electron spectrum of the device was measured at 0.6 mbar argon and 22 kV charging voltage, in four discrete energy intervals extending up to 500 keV. The results of the experiments show that most of the electrons are emitted in the 125-375 keV energy range and the spectral amplitude becomes negligible beyond 375 keV.

关键词： magnetized plasma plasma focus plasma diagnostics electron beam energyspectrum x-ray dosimetry