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Dive into the research topics where Jamal Chaouki is active.

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Featured researches published by Jamal Chaouki.


Powder Technology | 1985

Effect of interparticle forces on the hydrodynamic behaviour of fluidized aerogels

Jamal Chaouki; C. Chavarie; D. Klvana; G. Pajonk

Abstract Aerogel powders, particles of the group C according to the Geldart classification, are not particularly attractive as such for fluidized bed applications. The following study shows, however, that these fine solids form agglomerates above a minimum superficial velocity of 0.04 m/s and that the resulting new system fluidizes smoothly and homogeneously at room and at higher temperatures. A comprehensive model developed to represent the hydrodynamic behaviour of the system proposes that the agglomerate is a cluster of the original fixed bed materials and hence has the properties of the bulk matrix. Van der Waals forces on the elementary grains are used to predict the cluster size. This clustering process is finally analysed in the light of the classical fluidizability diagram.


Powder Technology | 2001

Local solid mixing in gas–solid fluidized beds

Navid Mostoufi; Jamal Chaouki

Abstract Diffusivity of the solid particles in a 152-mm ID gas–solid fluidized bed was determined at different regimes of fluidization. The gas was air at room temperature and atmospheric pressure and the solids were 385 μm sand or 70 μm FCC particles. The experiments were done at superficial gas velocities from 0.5 to 2.8 m/s for sand and 0.44 to 0.9 m/s for FCC (in both bubbling and turbulent regimes). Movement of a tracer was monitored by radioactive particle tracking (RPT) technique. Once the time-position data became available, local axial and radial diffusivity of solids were calculated from these data. Calculated diffusivities are in the range of 3.3×10−3 to 5.6×10−2 m2/s for axial and 2.6×10−4 to 1.5×10−3 m2/s for radial direction. The results show that the diffusivities, both axial and radial, increase with superficial gas velocity and are linearly correlated to the axial solid velocity gradient. Solid diffusivity in a bed of FCC was found to be higher than that of a bed of sand at the same excess superficial gas velocity.


Chemical Engineering Journal | 2000

Characterization of dynamic gas-solid distribution in fluidized beds

Heping Cui; Navid Mostoufi; Jamal Chaouki

Abstract A probability distribution model of the local voidage was proposed to describe and simulate dynamic gas–solid distribution in the bubbling and turbulent fluidized bed reactors. Experiments were carried out in an air-fluidized bed. The bed materials were FCC particles (Geldart A) and irregular sand particles (Geldart B). A cross-optical fiber probe was employed to measure dynamic voidage. The minimum probability method was introduced to identify the division between the emulsion phase and the bubble phase. The statistical analysis indicated that the two particle types employed have extremely different dynamic behaviors corresponding to different gas–solid distributions and the interaction between the bubble and emulsion phases. For the FCC particles, the voidage of the emulsion phase is very close to that at the minimum fluidization with little effect from the formation and motion of bubbles in bubbling regime, and deviates a little from emf in turbulent regime. For the sand particles, the voidage of the emulsion phase differs far from that at the minimum fluidization, and the bubble phase gradually becomes more dilute from bubbling to turbulent regime. However, for both particles the dynamic voidage fluctuations in the emulsion phase and the bubble phase followed beta distribution under various operating conditions. The probability density functions of the local voidage from emf to 1 showed the continuous double-peak phenomena, one peak for the emulsion phase and another for the bubble phase, and evolved with changing operating conditions and bed position. A particular distribution, called coupled beta distribution, was developed to describe and simulate such probability density function with double peaks and its complex evolution from bubbling to turbulent regime. The quantification of the probability density function then statistically introduced the spatiotemporal two-phase flow structure.


Powder Technology | 1992

Scaling considerations for circulating fluidized bed risers

Gregory S. Patience; Jamal Chaouki; Franco Berruti; R. Wong

Abstract The ratio between actual gas velocity to particle velocity in the hydrodynamically fully developed region of Circulating Fluidized Bed risers (CFB) may be approximated by ϕ=1+5.6/Fr+0.47Fr0.41t=Ug/ϵVp. This ratio, termed the slip factor, is about 2 at operating conditions characteristic of industrial risers several meters in diameter and agrees with observations of J. M. Matsen (in D. L. Keairns (ed.), Fluidization Technology, Vol. 2, Hemisphere, 1976, p. 135). The proposed relationship between the gas and solids velocity is an adequate first approximation to estimate gas and solids residence times, blower capacity and standpipe length.


Chemical Engineering Science | 2003

Axial dispersion in the three-dimensional mixing of particles in a rotating drum reactor

Richard G. Sherritt; Jamal Chaouki; Anil K. Mehrotra; Leo A. Behie

Horizontal drum reactors are widely used in industry for the processing of granular material. They are ideally suited for chemical processes that require high temperatures at near-atmospheric pressure. However, the complexities of these reactors have resulted in empirical design procedures that lead to very conservative and costly reactors. This study first reviews critically the extensive literature on experimental results obtained on rotary kilns (without flights) and proposes new design equations for the axial-dispersion coefficient in terms of rotational speed, degree of fill, drum diameter, and particle diameter. A total of 179 data points from the literature, encompassing both the batch and the continuous operational modes, yielded design correlations for slumping, rolling/cascading and cataracting bed behaviours. Additionally, new measurements were made on a pilot-scale rotary drum by tracking a single radioactive particle (emitting gamma-rays) using a battery of nine scintillation counters; these data confirmed the correctness of the proposed design correlations.


Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 1994

A γ-ray detection system for 3-D particle tracking in multiphase reactors

Faïçal Larachi; G. Kennedy; Jamal Chaouki

A system employing eight NaI detectors has been developed for tracking particles moving in a three-phase fluidized bed reactor. One particle is tagged with typically 2 MBq of 46Sc which emits high energy γ-rays. The system is calibrated by measuring the count-rates in the 8 detectors with the tagged particle placed at a number of locations in the reactor and then calculating the count-rates, using the Monte Carlo technique, at 19 200 locations. In a tracking experiment, data are accumulated in the multiscaling mode and the coordinates of the moving particle are calculatedby least-squares using the calibration map. With 30 ms counting intervals, the location of the particle is determined with a typical precision of 5 mm. The use of these data for determining velocity flow fields in multiphase reactors is illustrated.


Bioresource Technology | 2014

Extraction of phenols from lignin microwave-pyrolysis oil using a switchable hydrophilicity solvent.

Dongbao Fu; Sherif Farag; Jamal Chaouki; Philip G. Jessop

Microwave pyrolysis of lignin, an aromatic polymer byproduct from paper-pulping industry, produces char, gases, and lignin pyrolysis oil. Within the oil are valuable phenolic compounds such as phenol, guaiacol and catechol. In this work, we describe a method using switchable hydrophilicity solvents (SHS) to extract phenols as a mixture from lignin microwave-pyrolysis oil at the scale of 10 g of bio-oil. Even at this small scale, losses are small; 96% of the bio-oil was recovered in its three fractions, 72% of guaiacol and 70% of 4-methylguaiacol, the most abundant phenols in the bio-oil, were extracted and 91% of the solvent SHS was recovered after extraction. The starting material (lignin microwave-pyrolysis oil) and the three fractions resulted from SHS extraction were characterized by GC-MS and quantitative (13)C{(1)H} and (31)P{(1)H} NMR spectroscopy.


Fuel | 1998

Simulation of circulating fluidized bed reactors using ASPEN PLUS

R. Sotudeh-Gharebaagh; Robert Legros; Jamal Chaouki; J. Paris

A comprehensive model is developed for the combustion of coal in a circulating fluidized bed combustor (CFBC). The proposed model integrates hydrodynamic parameters, reaction model and kinetic subroutines necessary to simulate coal combustion in a CFBC. Kinetic expressions were developed for the char combustion rates and the SO2 absorption in the bed using data from the literature. The reaction model, which considers only the important steps of coal combustion, was simulated using four ASPEN PLUS reactor models and several subroutines. The developed subroutines were then nested in the ASPEN PLUS input file, so that the CFBC may be represented. The validity of the model was demonstrated using 14 different sets of operating conditions for the CANMET 0.8 MWth CFBC pilot plant.


Chemical Engineering Science | 1993

Gas phase hydrodynamics in the riser of a circulating fluidized bed

Gregory S. Patience; Jamal Chaouki

Abstract The hydrodynamics of a circulating fluidized bed (CFB) were studied using radioactive argon as a tracer. The impulse experiments show that gas passes through the riser at velocities significantly greater than superficial gas velocities. A core-annular flow model was used to describe the hydrodynamics. Axial dispersion in the core zone is negligible and mass transfer to the denser, stagnant annulus is characterized by a cross-flow coefficient, k . The Gilliland-Sherwood equation for wetted wall towers, modified to account for the increase in mass transfer rate introduced by the solids, correlates the data reasonably well: The ratio of the cross-sectional area of the lean core to riser cross-sectional area, Φ g , decreases with solids mass flux but increases with gas velocity. Based on a number of experimental investigations, the effects of riser diameter and particle characteristics on Φ g were qualified and the data were fit with a simple two parameter model: This relationship adequately predicts gas bypassing in risers from 0.05 to 0.94 m in diameter.


Applied Catalysis A-general | 1994

Combustion of methane over La0.66Sr0.34Ni0.3Co0.7O3 and La0.4Sr0.6Fe0.4Co0.6O3 prepared by freeze-drying

D. Klvana; J. Vaillancourt; Jitka Kirchnerova; Jamal Chaouki

A kinetic study of methane combustion at low temperatures (648 to 923 K) over La0.66Sr0.34Ni0.3Co0.7O3 and La0.4Sr0.6Fe0.4Co0.6O3 perovskites, both prepared by spray-freezing/ freeze-drying, has been carried out to determine the kinetic parameters for simple models suitable for use in reactor design and in reactor performance evaluation. The two tested models, a simple first-order modelr =k·PCH4, and a two-term modelr = (k1 +k2.P0.5O2PCH4 are related to the re mechanism. The first-order model gave a good fit to the experimental data for La0.66Sr0.34Ni0.3Co0.7O3 and was found adequate also for La0.4Sr0.6Fe0.4Co0.6O3. However, in the case of the latter catalyst the experimental data were best described by a Mars-van Krevelen model. The activity of the two catalysts is very good and stable, but the nickel-based catalyst is more active.

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Christophe Guy

École Polytechnique de Montréal

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François Bertrand

École Polytechnique de Montréal

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Gregory S. Patience

École Polytechnique de Montréal

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Robert Legros

École Polytechnique de Montréal

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Jean-Philippe Laviolette

École Polytechnique de Montréal

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Jaber Shabanian

École Polytechnique de Montréal

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Jocelyn Doucet

École Polytechnique de Montréal

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Sherif Farag

École Polytechnique de Montréal

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C. Chavarie

École Polytechnique de Montréal

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