Papers by behdad moghtaderi
Combustion and flame spread on fuel-soaked porous solids
Progress in Energy and Combustion Science, 2013
Fires caused by accidental spillage of flammable liquids have been a major safety concern in indu... more Fires caused by accidental spillage of flammable liquids have been a major safety concern in industries and urban areas. There has been a recent surge of interest in the research concerning the combustion and flame spread over an inert porous media soaked with flammable liquid. This interest has been driven by the need to better understand fire and its behaviour under these conditions and improve the relevant fire safety and prevention technologies. A review of key studies in this subject area has been conducted and summarised, focussing mainly on the theory plus a notable experimental findings about combustion and the flame spread phenomena of fuel-soaked porous media. The review covers topics such as flame spread behaviour, physical flame propagation aspects, heat transfer, temperature distribution; and fuel consumption over inert porous media. The review concludes with some practical safety and environmental considerations for decontamination of land soaked with flammable liquid.
Australia is amongst the forefront of Enhanced Geothermal System (EGS) and Hot Sedimentary Aquife... more Australia is amongst the forefront of Enhanced Geothermal System (EGS) and Hot Sedimentary Aquifer (HSA) ventures. With no active extensional regimes generating high-permeability systems of fluid-borne crustal heat, commercially-viable geothermal systems in Australia depend on trapping heat from radiogenic decay.
A Novel Miniaturised Fuel Reformer for On-board Hydrogen Enrichment of Gaseous and Liquid Fuels in Combustion Systems
Chemeca 2010: Engineering at the Edge; 26-29 September 2010, Hilton Adelaide, South Australia, 2010
Experiments were conducted in a thermogravimetric analyser (TGA) and a prototype miniaturised mic... more Experiments were conducted in a thermogravimetric analyser (TGA) and a prototype miniaturised micro-reactor on magnetite (Fe3O4) and wuestite (FeO) metal oxides under both pure methane and pure steam environments. Results show that the concentration of methane in the product gas gradually decreases while Fe3O4 is being transformed to FeO. However, on or about a fractional conversion of 60% the slope of the CH4 plot sharply increases. This profound change can be attributed to catalytic effect of FeO on methane decomposition. Similarly, the H2 plot picks up rapidly and reaches its maximum value of 98% at a fractional conversion of 30%. The conversion times in the micro-reactor were found to be much shorter than TGA experiments.
Powder Technology, 2018
This article reports an investigation on the explosion characteristics of methane-coal dust hybri... more This article reports an investigation on the explosion characteristics of methane-coal dust hybrid mixtures in a ducted spherical vessel. Methane-coal dust hybrid mixture explosion can occur in coal mines and spread into mine tunnels. While investigating the effects of methane addition to coal dust-air mixtures, the violence of coal dust explosions was found to increase significantly in the presence of methane. The energy of ignition was found to impact on the pressure rises in the vessel and in the duct. The experimental data and scientific analysis presented can assist in addressing ducted explosions originating from hybrid mixtures in process industries such as coal mines.
Fuel, 2019
Heat recovery from a fluidised-bed ventilation air methane abatement reactor and conversion into ... more Heat recovery from a fluidised-bed ventilation air methane abatement reactor and conversion into power using a Rankine cycle based steam turbine and cooling via an absorption chiller was simulated using the process simulation package Aspen Plus. The primary aim of the simulation was to determine the minimum methane concentration for self-sustaining operation, both in terms of maintaining the oxidation process at high temperature and to generate sufficient power to operate the plant. For a ventilation air flow rate of 20 m 3 /s (equivalent to a single abatement module), the minimum methane concentration was found to be 0.46 vol% at a reactor temperature of 650 °C and ambient pressure. The Rankine cycle operated with a steam pressure of 7.0 bar and steam flow rate of 0.4 kg/s. At the minimum methane concentration the process was self-sustained with zero net power being produced. The cooling produced at 0.46 vol% was 680 kW R using an indirect-fired absorption chiller while 780 kW R was produced via a direct-fired absorption chiller. Assuming a total ventilation air flow rate of 300 m 3 /s, fifteen 20 m 3 /s modules would be required, producing a total of up to 11,700 kW R of cooling. The net power produced was zero between reactor temperatures of 500 and 700 °C at the investigated steam pressures (2.0-7.0 bar). Excess net power was produced at reactor temperatures greater than 700 °C due to the restriction of the inlet VAM temperature to 600 °C (to prevent auto-ignition of the methane upstream of the reactor). At low reactor temperatures the steam flow rate decreased with both reactor temperature and steam pressure but remained constant at reactor temperatures of 750 and 800 °C. The methane abatement plant would be able to operate without an external power supply through the utilisation of the process heat. The plant would produce adequate cooling for a typical gassy underground coal mine in Australia. Such mines are located in the Bowen Basin of Queensland; a region characterised by high virgin rock temperatures with cooling requirements of up to 7000 kW R .
Fuel, 2017
Coal is a major resource in Australia, both for power generation and as an export good, however i... more Coal is a major resource in Australia, both for power generation and as an export good, however its environmental impact is of significant concern. The structure of coal is inherently complex and contains many heteroatoms, which negatively affect the combustion efficiency and cause pollution. This study reveals that pretreatment of two types of Australian coal, a lignite coal and a thermal bituminous coal, with low cost choline amino acid based ionic liquids, markedly reduces the particle size and heteroatom content. This method is rapid (3h) and proceeds at a low temperature of 70 °C. FTIR, NMR and TGA analysis revealed that pretreated coal has reduced aliphatic carbon, carbonyl groups and sulfur compared to untreated coal. Choline arginate was the best perfoming pretreatment agent for both types of
Technical Issues Associated with Co-combustion and Ash Deposition
This chapter provides a detailed assessment of two major groups of technical issues associated wi... more This chapter provides a detailed assessment of two major groups of technical issues associated with the cofiring of coal and biomass in pulverised fuel boilers. These are: (i) combustion-related issues; and a brief overview of (ii) issues related to ash deposition. The emissions and ash disposal issues are dealt with separately in detail in Chapter 6. A series of examples is also presented in Chapter 8 to show the extent to which the technical issues discussed in Chapters 4-6 impact upon a cofiring operation and to demonstrate the most effective course of action to resolve these problems in a practical situation.
2013 IEEE 14th International Conference on Information Reuse & Integration (IRI), 2013
Network. The purpose of this paper is to conduct a comparative study on the accuracy of classific... more Network. The purpose of this paper is to conduct a comparative study on the accuracy of classification models and reduce the credit risk. In this paper, we use data mining of enterprise software to construct four classification models, namely, decision tree, logistic regression, neural network and support vector machine, for credit scoring in banking. We conduct a systematic comparison and analysis on the accuracy of 17 classification models for credit scoring in banking. The contribution of this paper is that we use different classification methods to construct classification models and compare classification models accuracy, and the evidence demonstrates that the support vector machine models have higher accuracy rates and therefore outperform past classification methods in the context of credit scoring in banking.
Energy & Fuels, 2015
The larger reactor volume, additional oxygen polishing unit and carbon stripper for separation of... more The larger reactor volume, additional oxygen polishing unit and carbon stripper for separation of 2 oxygen carrier and ash in the chemical looping combustion (CLC) and/or chemical looping oxygen 3 uncoupling processes for solid fuels are anticipated not only to incur operational complexity but also 4 increase the capital and operating costs. As an alternative, this paper proposes a novel hybrid process -5 called "Chemical Looping Oxy Combustor (CLOC)". This novel process provides an integration of 6 chemical looping air separation (CLAS) with fluidized bed oxy-fuel combustion and is expected to 7 eliminate the need for an additional oxygen polishing unit and carbon stripper. It can be retrofitted to 8 any existing coal CFB at low cost. The other advantages of CLOC includes less solid handling issues, 9 flexibility in handling low grade coal with high moisture, no/less contamination of oxygen carriers, 10 no/less slip of CO 2 /SO x in air reactor and low energy penalty etc. Also, in CLOC process coal 11 combustion will occur in a separate fluidized bed combustor with relatively faster kinetics due to the 12 availability of high oxygen concentration (i.e. ~25-28 vol%) which eliminates the need for a larger fuel 13 reactor volume. In the current paper, thermodynamic simulations of CLOC process using Cu-, Mn-, 14 and Co-based metal oxide oxygen carriers were carried out. Their performances were also compared 15 against the conventional air-firing and oxy-firing technologies, e.g. oxy-fuel combustion integrated 16 with cryogenic air separation unit (CASU) and chemical looping oxygen uncoupling (CLOU). It was 17 identified that CLOC process needs external heat for reduction reactor provided by either direct or 18 indirect methane combustion. Moreover, a maximum plant thermal efficiency was achieved for CLOC 19 using Cu-based oxygen carrier. The energy penalty of CLOC process, compared with the air-firing 20 base case, was found to be approximately 2-3%, about 4-5 times smaller than those of the CASU cases 21 and only half of that of the CLOU process, indicating that CLOC offers a promising option for 22 combustion of solid fuels. 23
The co-pyrolysis and co-gasification of binary blends of a bituminous coal (PT), a petcoke (PC) a... more The co-pyrolysis and co-gasification of binary blends of a bituminous coal (PT), a petcoke (PC) and two types of biomass (olive stones, OS; chestnut, CH) were studied at atmospheric pressure in a fixed bed reactor. The pyrolysis and gasification were performed under nitrogen, and steam/oxygen atmospheres, respectively. In a fixed bed reactor, the particles of the different fuels are in close contact, providing an optimum means for evaluating possible synergetic effects. Pyrolysis tests showed a lack of chemical interaction between the components of the blend. Therefore, the composition of the gas produced during the pyrolysis tests can be predicted from those of the individual components and their mass fractions. During the co-gasification tests, different interactions were observed depending on the heating rate. Low heating rates produced higher amount of CO and CO 2 , whereas tar yield decreased. At high heating rates, the biomass and coal blends produced more tar but less H 2 and CO. The effect of co-gasification on apparent thermal efficiency was also evaluated.
Process Safety and Environmental Protection, 2000
Journal of Fluid Mechanics, 2006
This paper reports on a lattice Boltzmann simulation of laminar mixing in a coaxial microreactor ... more This paper reports on a lattice Boltzmann simulation of laminar mixing in a coaxial microreactor at low Reynolds numbers. The main focus of the study was to compare the effectiveness of a multi-holed baffle plate, a set of 2 × 2 square bars, and a flat-plate arrangement on the enhancement of reagent mixing inside the reactor. It was found that all three mixers increased mixing through the mechanism of generating coherent structures, which in turn increased interface contact between the fluid streams. However, for this particular microreactor, the efficiency of each mixer depended on its ability to generate coherent structures with high helicity and thereby inducing a swirl motion to the flow.
Kinetics and Mechanism of Catalytic Oxidation of Formaldehyde over Hydrophobic Catalysts
Industrial & Engineering Chemistry Research, 1994
Catalytic oxidation is an attractive way to reduce volatile organic compound (VOC) emissions to m... more Catalytic oxidation is an attractive way to reduce volatile organic compound (VOC) emissions to meet the requirements of air pollution control regulations. The kinetics and mechanism are reported for the oxidation of formaldehyde with air over a hydrophobic catalyst. The measured catalyst activity and selectivity varied with temperature. A mathematical model, based on the Mars-van Krevelen mechanism, has been developed
High Temperature, 2000
Considering the developing role of the friction stir welding in manufacturing industry, a complet... more Considering the developing role of the friction stir welding in manufacturing industry, a complete study on the process is necessary. Studies on each stage of the process in particular, provide a better understanding of friction stir welding, and specially friction stir spot welding. In this study, plunge stage has been studied by experimental methods for investigating the temperature distribution around the tool during the plunge stage and microstructure changes of the workpiece. Experiments were performed on aluminium 7050 plates with coincident measurement of temperature. In the study, the tool which has a triangle pin is used. The results of this study are used as initial conditions for theoretical analysis of welding process. The results show that the temperature distribution around the tool is quite asymmetric. The asymmetric distribution of temperature is due to nonuniform load distribution underneath the tool and tilt angle of it. The temperatures of the points behind the tool are higher compared with points located forward the tool. Microstructural studies showed that four regions with different microstructures are formed around the tool during the process. These areas were separated based on differences in grain size and elongations. Grains near the tool are elongated in a particular direction that show the material flow direction.
Differences in reactivity of pulverised coal in air (O2/N2) and oxy-fuel (O2/CO2) conditions
Fuel Processing Technology, 2009
... Keywords: Oxy-fuel combustion; Pulverised coal; Char; Gasification; Reactivity; TGA. Article ... more ... Keywords: Oxy-fuel combustion; Pulverised coal; Char; Gasification; Reactivity; TGA. Article Outline. ... In summary, the rates of combustion in oxy-fuel combustion may differ from air conditions, with identified mechanisms consistent with both improved and worsened rates. 2.2. ...
Short Communication: a methodology for evaluating the effect of drying on the heat of combustion of wood-based materials
Fire and Materials, 2000
Fire and Materials, 2012
ABSTRACTFlame spread over porous media due to accidental fuel spillage is a major fire safety con... more ABSTRACTFlame spread over porous media due to accidental fuel spillage is a major fire safety concern. The behaviour of flame under such conditions greatly depends on the availability of fuel at combustion zone. A combined experimental and mathematical study was carried out to investigate the rate of fuel penetration through porous beds at different fuel ratios. Propanol at three different fuel ratios of 0.1, 0.125 and 0.15 and sand particles ranging in diameters from 0.5 to 5 mm were employed as liquid fuel and porous bed, respectively.Results showed that fuel penetration rate was a function of permeability of porous bed and mass of the liquid fuel. The permeability of porous bed and consequently the rate of fuel penetration decreased as either the tortuosity or the specific surface area was increased.Fuel penetration measurement and mathematical results indicated that the rate of fuel penetration is directly proportional to the fuel ratio. The fuel penetration rate was found to be...
Experimental Thermal and Fluid Science, 2004
Gravity currents are important physical phenomena which have direct implications in a wide range ... more Gravity currents are important physical phenomena which have direct implications in a wide range of physical situations including geophysical processes, air conditioning, and building fires where they are responsible for the transport of smoke and hot gases, particularly, along long corridors. Despite recent progress in the field, relatively little is known about the structure of gravity currents under conditions pertinent to building fires. In particular, the impact of heat transfer at boundaries is not well understood. The present investigation is an attempt to address this shortcoming by studying the turbulent structure of gravity currents under both adiabatic and isothermal boundary conditions. For this purpose, a series of experiments was conducted in a rectangular tank with turbulent underflows. Laser Doppler velocimetry was employed to quantify the velocity field and associated turbulence parameters. Experimental results indicated that the mean flow within the head region primarily consisted of an undiluted large single vortex which rapidly mixed with the ambient flow in the wake region. Flows with isothermal wall boundary conditions showed three-dimensional effects whereas those with adiabatic walls exhibited two-dimensional behaviour. Turbulence was found to be highly inhomogeneous and its distribution was governed by the location of large eddies. While all components of turbulence kinetic energy showed minima in the regions where velocity was maximum (i.e. low fluid shear), they reached their maximum in the shear layer at the upper boundary of the flow.
Coal Ash Buildup on Ceramic Filters in a Hot Gas Filtration System
Energy & Fuels, 2003
Energy & Fuels, 2012
This study is concerned with the reduction/oxidation (redox) behavior of bimetallic oxygen carrie... more This study is concerned with the reduction/oxidation (redox) behavior of bimetallic oxygen carries of Ni and Fe under conditions pertinent to chemical looping combustion (CLC). Bimetallic oxygen carriers of Ni-and Fe-based metal oxides with different mixture ratios were developed through the incipient wet impregnation (IWP) method by employing SiO 2 as the support. The redox properties of metal oxide mixtures were determined in a magnetic balanced thermogravimetric analyzer (TGA) over a range of temperatures between 500 and 950 °C at atmospheric pressure under alternating reduction and oxidation half cycles. The reduction half cycle was carried out in the presence of CO, CO 2 , and N 2 mixtures with different volume fractions of CO (typically 5, 10, and 70%), while the oxidation half cycle was conducted in normal air. Oxygen carriers exhibited temperaturedependent reactivity during both reduction and oxidation half cycles. The reactivity of monospecies Ni-based oxides on the silica support under the reducing environment of CO was found to be lower than that of Fe-based oxides. Furthermore, with the exception of 950 °C, reaction rates and the extent of reactions at high temperatures were generally found to be higher than those of low temperatures. The kinetic properties of all monospecies and bimetallic oxygen carriers were determined using the shrinking core model, from which the mixture kinetics of nickel and iron oxide on the SiO 2 support were further correlated to the mixture ratio through a detailed theoretical analysis.
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Papers by behdad moghtaderi