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issue International Review of Chemical Engineering (Rapid Communications) - January 2009 - Preface and acknowledgments
International Review of Chemical Engineering (Rapid Communications) - January 2009 - Papers
International Review of Chemical Engineering (Rapid Communications) - Preface and acknowledgments
by the Editor-in-Chief prof. Jordan Hristov
International Review of Chemical Engineering (Rapid Communications) - Papers
by Guillermo Rein Vol. 1. n. 1, pp. 3-18
Abstract - Smouldering is the slow, low-temperature, flameless form of combustion of a condensed fuel. It poses safety and environmental hazards and allows novel technological application but its fundamentals remain mostly unknown to the scientific community. The terms filtering combustion, smoking problem, deep seated fires, hidden fires, peat or peatlands fires, lagging fires, low oxygen combustion, in-situ combustion, fireflood and underground gasification, all refer to smouldering combustion phenomena. This paper attempts to synthesize a comprehensive view of smouldering combustion bringing together contributions from diverse scientific disciplines. Smouldering is the leading cause of deaths in residential fires and a source of safety concerns in space and commercial flights. Smouldering wildfires destroy large amounts of biomass and cause great damage to the soil, contributing significantly to atmospheric pollutant and green house gas emissions. Subsurface fires in coal mines and seams burn for very long periods of time, making them the oldest continuously burning fires on Earth. Worthy of consideration are the novel environmental and energy technologies being developed based on the direct application of smouldering combustion. These include the remediation of contaminated soils, production of biochar for long term storage of carbon, enchanted oil extraction from reservoirs and gasification of coal seams. The prospect of new opportunities for science and engineering in smouldering combustion are noticeable, but a much larger international research effort is required to increase the number of multidisciplinary experimental, theoretical and field studies. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fire; Safety; Subsurface;Forest; Emissions; Carbon; Biomass; Multidisciplinary; Smoldering.
Vol. 1. n. 1, pp. 19-43
Abstract - Odours in potable waters are the major complaint repeated by customers worldwide. Water utilities have justified or ignored them, because, in most cases, the odorous waters satisfy all of the water laws and registration requirements. For customers however, odour is often the primary judgement of water quality. Odour problems are usually caused by Aqueous Organic Matter (AOM). Furthermore, the AOM can be produced as unexpected by-products (e.g. disinfection by-products) during water treatment processes. Hence, eliminating AOM during water treatment is one of the highest priorities in water utilities. Several investigations have been performed for the identification, characterization, treatment options, and treatability of the AOM. Unfortunately, these researchers have proved that the Conventional Potable Water Treatment (CPWT) processes, which consist of coagulation, sedimentation, rapid media filtration and disinfection, are not suitable for reducing the AOM concentration to a level low enough to alleviate odour problems. These researchers have also justified the introduction of advanced or alternative processes such as granular activated carbon bed adsorption, ozonation and membrane filtration for improving AOM removal. The goal of this review is to look at the research which has been done in this area and to find out the best available operations, in terms of AOM reduction, in current CPWT plants for minimizing odour, that can be performed easily and demand minimum budget and modification. For this purpose, options available such as enhanced coagulation, powdered activated carbon adsorption, oxidation and membrane filtration will be investigated and their efficiencies assessed in comparison with the performance of CPWT processes. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Potable water; Odour; Aqueous organic matter; Treatment options.
Vol. 1. n. 1, pp. 44-50
Abstract - This is an experimental study of the process of film evaporation of blends of dehydrated slow pyrolysis bio-oil with light diesel fuel. Four fuel batches were tested: 100% bio-oil, 70% bio-oil and 30% diesel fuel, 30% bio-oil and 70% diesel fuel, and 100% standard light diesel fuel. The bio-oil used in this study was produced in a kiln from local pine trees (mainly Pinus Peuce also known as Macedonian Pine) from the Rila Mountain region, Bulgaria. The fuel films coated the outer surface of a quartz fibre, which was irradiated by a tungsten incandescent bulb. The bulb was used as a heater and a source of visual light with a constant effective emissive power of 465 W/m2. The experiments showed that the evaporation of the fuel samples strongly depends on the composition of the blends. The pure diesel fuel sample exhibited fast and complete evaporation. The bio-oil and the blends showed an incomplete evaporation that, depending on the presence of volatile fractions, resulted in: (i) formation of amorphous tar-like matter; (ii) formation of a sponge-like shell; or, (iii) swelling of the film, followed by the core matter eruption and formation of a hollow core surrounded by a thin and smooth shell. The film surface regression rate followed a progressive law with a time dependent rate constant. Several physical models are considered as bases for further mathematical modelling. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: bio-oil, diesel fuel, film-evaporation, thermal radiation, heat-transfer, shell.
Vol. 1. n. 1, pp. 51-57
Abstract - The pollution of environment and the changes of climate are caused directly by the CO2 emission in combustion process of coal. Chemical looping combustion could easily concentrate CO2 in combustion processes by efficient and energy-saving ways. A new compound oxygen carrier with calcium sulfate and metal oxides is prepared by impregnation method in this paper. The reaction in thermal gravimetric analyzer between the compound oxygen carrier and some gaseous fuels such as CO and some solid fuels such as coal char is investigated. The reaction rate between the compound oxygen carrier impregnated with trace Fe2O3 and NiO and solid fuels is much faster than that between CaSO4 oxygen carrier and solid fuels. Fe2O3 addition improves the reaction performance of oxygen carrier with solid fuels more than NiO. Furthermore, different influencing factors, including pressure, fuel reactor temperature, and oxygen excess number, on the formation of carbon deposits and sulfur evolution are investigated. It can be predicted that the temperatures in the range from 900 to 1050 °C, the pressure form 1 to 5 bar and the excess oxygen number from 0.9 to 1.1 can be regarded as the optimum operation conditions. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Chemical-looping combustion, compound oxygen carrier, carbon deposits, impregnation method, sulfur evolution.
Vol. 1. n. 1, pp. 58-65
Abstract - Previous attempts to determine the amount of volatile material transferred into and burnt in the freeboard region (FBR) of fluidized bed coal combustors have been few and/or ambiguous. A major reason for this is the difficulty of separating the two combustion processes (volatiles and char) occurring simultaneously within both bed and freeboard sections, and because the instrumentation for measuring these separate phenomena directly is non-existent. Therefore, a calorimetric technique is reported here to produce quantitative information on the fraction of heat released by the volatile component in the FBR. The calorimetric experiments revealed that over one third of the original volatiles may be released and burnt above the bed at low excess air levels (< 10 %) and low bed temperatures (< 850°C), for shallow beds (0.2 m) and small bed particle size (0.674 mm); while a low transfer of volatile matter was measured at high bed temperatures (> 850°C) and high excess air levels (up to 40 %). The transfer of coal volatiles in the FBR was found to be influenced by the in-bed operating and fluidizing conditions in the following order: bed temperature (Tb), excess air (XSA), fluidizing velocity (Uo) and coal particle size (dc). Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Coal Volatiles, Combustion, Fluidized Beds.
Vol. 1. n. 1, pp. 66-73
Abstract - A heat and mass transfer and energy management problem of for hydromagnetic flow with magnetic effect micropolar fluids past through a stretching sheet has been studied. Governing equations are included continuity equation, momentum equation, angular momentum equation, energy equation and the concentration equation of a micropolar fluid have been analyzed by a combination of the similarity transformation and a accurate finite-difference method. These solutions are used to obtain distributions of the local convective heat transfer coefficient and the stretching sheet temperature. The ranges of these dimensionless parameters, the Prandtl number Pr, the magnetic parameter M, the material parameter K, the Eckert number Ec and the Schmidt number Sc are from 0.3 to 0.71, 0 to 20, 0 to 2, 0 to 0.8 and 0.5 to 10, respectively. The numerical results indicate that, an increase in the magnetic parameter gives a decrease in the values of the velocities and Nusselt number, or an increase in the values of the shear stress, couple stress at the surface, temperature and concentration. The material parameter has the opposite effect of magnetic field parameter on the values of the velocities, temperature, concentration, shear stress, Nusselt number and Schmidt number. The temperature decreases as the Prandtl number increases, or increases as the Eckert number increases. The concentration decreases as Schmidt number increases. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Heat and mass transfer, Energy management, Magnetic field, Micropolar fluid, Stretching sheet, Finite difference method.
Vol. 1. n. 1, pp. 74-80
Abstract - In this work the effect of air humidity on powder flow properties was studied by means of a ring shear tester. Powder sample moisture content was conditioned by humid air in a fluidization column. In spite of the very low moisture contents in the powder (<0.2%) obtained by this technique, a significant change in the powder cohesion was observed. The Kelvin equation was used to infer on the pressure increase inside the capillary bridge and the resulting typical interparticle force. This result was used to derive the powder tensile strength following the Rumpf approach and compare it with values derived from shear experiments. A single fitted value of the unknown capillary bridge gap is able to provide quantitative agreement for experiments with highly humid air. Model estimation indicates that water mainly condenses on rough surfaces of the particles and only a small portion of this condensed humidity contributes to change the powder flow properties in interparticle capillary bridges. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: cohesive powder behavior, flow properties, humidity.
Vol. 1. n. 1, pp. 81-86
Abstract - In this study, the behaviour of binary-solid liquid fluidized beds was investigated, with particular reference to the transition from the fixed to the fully fluidised state. We report here the results of the first part of the investigation, which focused exclusively on binary-solid mixtures in which the solid species differ only with regard to the densities of the two materials. In keeping with previous studies on gas-solid systems, the experiments confirm the concept of a minimum fluidization velocity - a relatively well defined one for mono-solid-component suspensions - to be inapplicable for binary-solid-component systems, where the transition from the fixed to the fully fluidized state is an altogether more complex phenomenon. In particular, the behaviour depends critically on the initial state of the system: whether fully segregated, for example (with a layer of the more dense solid below one of the less dense, or viceversa), or completely homogeneously mixed throughout the column. Experimental investigations, quantifying the bed behaviour by means of visual observation as well as overall and local pressure drop measurements, are reported and discussed in detail for each of these situations. Simple force balance considerations are shown to provide quantitative predictions of the main observed phenomena. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fluidized beds, Minimum fluidization velocity, Binary solid mixture.
Vol. 1. n. 1, pp. 87-99
Abstract - Thermal energy storage systems that make use of latent heat involve a moving solid-liquid interface. Part I of this study examines the problem of one-dimensional melting in a finite slab with convective boundary conditions using the Heat Balance Integral technique. The slab is analyzed for the situation where the fluid temperature on one side of the slab is above the fusion temperature and on the other side below the fusion temperature. The slab is initially assumed to be solid at fusion temperature or subcooled. The results obtained predict the rate at which phase-change occurs (i.e., solid-liquid interface position as a function of time) and provide the temperature distribution in the solid and liquid regions at various times. Analytical solutions exist only for a special case of these problems and are compared to solutions obtained using the heat balance integral method. This study reveals, depending on the relative strength of convection, that either full or partial melting of the slab can occur which is essential information needed in the design of efficient phase-change TES systems. A direct simple formula is also developed that can be used to calculate the final melting interface position, given any particular values of Biot numbers and fluid temperatures on both sides of the slab. The final interface location obtained using the transient integral technique is compared with that obtained using the proposed formula to further validate the results. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Melting, Finite Slab, Integral Heat Balance Method, Convection.
Vol. 1. n. 1, pp. 100-108
Abstract - The freezing of a slab of finite thickness subjected to convective boundary conditions at both ends are studied in this paper. The Heat Balance Integral technique is employed (same as that used in Part I) to obtain freezing solutions for this one-dimensional problem. The slab is analyzed for its initial condition being either at fusion temperature or above (a superheated liquid). The rate of freezing and the temperature distribution in the solid and liquid regions are obtained. The solutions are validated for special cases by comparing with the available analytical solutions. The effect of enhancing the thermal conductivity on the freezing process is also investigated. Provided the Biot numbers and fluid temperatures on both sides of the slab are known, a direct simple formula is developed which predicts the final freezing interface position and this is shown to match well with the results obtained from the Heat Balance Integral Method. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Freezing, Finite Slab, Integral Heat Balance Method, Convection.
Vol. 1. n. 1, pp. 109-116
Abstract - Several non-intrusive laser diagnostic techniques (PIV, Marker Nephelometry and PLIF) were applied to study spray impact morphology: droplets velocity and size prior and after the impact, the number of droplets in the impact and post-impact zones, and the presence of vorticity fields in the impact area, at a temperature lower than the critical Nukiyama and Leidenfrost temperatures. The experimental results suggest that the process of droplet post-impact atomisation follows a hydrodynamic mechanism in which the first droplets that hit the wall form a liquid film. Later, the film breaks up because of the impact of the next incident dropletsm. As a result, a small number of relatively large post-impact droplets of low velocity is formed and pushed away from the zone of impact. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Spray, Droplet, Film, Atomisation, PIV, Mie Scattering, PLIF.
by Xin-Rui Li, Hiroshi Koseki Vol. 1. n. 1, pp. 117-120
Abstract - To evaluate the thermal safety of lithium battery, its electrolyte was assessed by CHETAH (Chemical Thermodynamic and Energy Release) and measured by a Differential scanning calorimeter (DSC), since it is a reactive material and causes accidents. Moreover, thermal reactivities of coin type primary lithium, silver oxide and alkaline batteries were analyzed by using a modified closed pressure vessel test (MCPVT). As a result, lithium battery is more hazardous than the other types of batteries. This might be a reason why recently with its increasing usage or disposal, accidents increased when used lithium batteries are thrown into other domestic wastes. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Coin type primary battery, Lithium, Thermal reactivity, Waste management, Hazard.
by Ahmed Aidan, Mehrab Mehrvar, Taleb Hassan Ibrahim, Valentin Nenov, Raafat Alnaizy Vol. 1. n. 1, pp. 121-125
Abstract - Laboratory-scale experiments were conducted to study the treatment of phenol contaminated wastewater using submerged ceramic membrane bioreactor (SCMBR) with flat-sheet-type ceramic membrane module. The effects of organic loading rate on the phenol degradation were studied using Polyseed bacteria containing a mixed culture of microorganisms with and without acclimatization. The experimental results showed that the phenol removal efficiency was over 75% at phenol concentrations of 400 mg/l with the COD removal efficiency of greater than 80%. For phenol concentrations of 800 mg/l, the removal efficiency dropped to about 40%, however, the system returned to its previous treatment efficiency once the phenol load was removed. As a result, it was observed that the bacteria survived at the high load phenol concentration of 800 mg/l. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Phenol degradation, submerged ceramic membrane bioreactor, SCMBR, organic shock load.
Vol. 1. n. 1, pp. 126-133
Abstract - Heat transfer studies were carried out in a laboratory scale bubbling fluidized bed reactor with 54.5 mm internal diameter, using five different sizes of silica sand particles: 107.5, 142.5, 180, 282.5 and 357.5 μm. The bubbling bed region was heated by a 2 kW electrical resistance and the heat was transferred towards a membrane cooling wall placed above the free surface of the bed. The bed temperature range covered by the experiments went from 400 to 700 ºC and a correlation for the global heat transfer coefficient is proposed. Two heat transfer mechanisms are responsible for the thermal energy transportation towards the membrane cooling walls: i) the convective heat transfer from the mainly fluidizing air flow; ii) the heat carried by the bed solid particles in the to-and-from movement created by their upward projection, due to the bursting bubbles reaching the bed surface, their collisions against the membrane walls and subsequent return to the hot bubbling bed. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Bubbling fluidized bed, Heat transfer, Membrane walls.
Vol. 1. n. 1, pp. 134
This book goes far beyond the promise of its title, and it is a wide compendium of the present state of the knowledge in the modeling of stress and velocity distributions for flowing and non flowing granular materials. This makes this book an important reference for scientists and engineers working on granular matter. The book is not only theory and most of the chapters start with an overview of the experimental observations that justify the specific modeling approach proposed in the corresponding chapter. In the first chapter the fundamentals of the physics and the basic balance equation that are relevant to particulate systems are presented. Chapter 2 to 4 are devoted mainly to plain silo flow and, more in general, to those systems that can be approached by continuum mechanics in two dimensions. The simplified geometry allows to introduce and discuss in simpler cases most of the assumptions made in the stress and strain analyses involving granular materials. Chapters 5 and 6 extend the application of continuum mechanics to cases involving tree dimensional flow and, in particular, to axy-symmetric bins. The most important powder constitutive equations involving yield and non yield conditions are also discussed in these chapters. The last four chapters are devoted to the modeling of fast granular flow by the approach of the kinetic theory. In particular, chapters 7 and 8 address the kinetic theory that can be derived by assuming smooth inelastic particles and its applications. In chapter 9 the velocity distribution functions and the particulate solids constitutive equation are compared for the two cases of smooth and rough particles. Two features of this book make it suitable for adoption as a text book in a university course for graduate students on granular flow. The first is represented by more than sixty pages of 11 appendixes most of which summarize the basics of the tensor analysis. The second feature is represented by the large number of exercises promoting meditation on the main concepts presented in the text and their application. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
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