1,721,001 research outputs found
Mathematical modeling of monolith reactors for photocatalytic oxidation of air contaminants
No full textA distributed parameter model for photocatalytic oxidation of air contaminants in monolith reactors is presented. Heat and mass balance equations for monolith structure are combined with a model of irradiation from a light source and a kinetic model for photon adsorption and chemical reaction to describe the processes of heat, mass and photon transfer within the system and the heterogeneous chemistry at the catalyst surface. The model accounts for interaction between light and matter at the catalyst surface, convective and interphase gas-solid heat and mass transfer, reaction at the catalyst surface and heat conduction within the solid structure. Together with detailed axial profile of temperature and conversion in the gas phase and at the catalyst surface under different operating conditions (inlet gas temperature, composition and flow rate, light source power, monolith geometry), the model provides the distribution of photon flux along the channels and allows the discrimination between thermal and pure photonic effect on the overall rate of conversion. (C) 1998 Elsevier Science S.A. All rights reserved
Particle-based biofilm reactors for the bioremediation of infiltration water contaminated by aromatic sulfonates
No full textAn experimental model of biofilm detachment in liquid fluidized bed biological reactors
No full textDimensional analysis was applied for the description of biofilm detachment in liquid fluidized bed biological reactors. This technique allowed the identification of the significant parameters influencing detachment mechanisms and suggested suitable experiments for the characterization of involved phenomena. The influence of the significant variables was established on a lab-scale reactor and an empirical model was proposed to correlate experimental results. The detachment rate was strongly dependent on liquid velocity, while the influence of other parameters, such as solid hold-up and liquid shear stress, was found to be less important. (C) 1996 John Wiley & Sons, Inc
Mixing and segregation in water fluidised-bed bioreactors
No full textThe complete segregation model, already successfully tested for binary-solid liquid fluidised beds of smooth rigid particles. has been applied to fluidised-bed bioreactors. Qualitative comparison with reported experimental behaviour has shown the capability of the model to predict solid mixing and segregation in these specific types of fluidised beds. (C) 1997 Elsevier Science Ltd
Denitrification performance of Pseudomonas Nitrificans in a fluidised bed biofilm reactor and in a stirred tank reactor.
No full textMechanisms of biofilm detachment in fluidized bed reactors
No full textBiofilm detachment in liquid fluidized bed biological reactors was investigated to point out how different mechanisms influence the process. Erosion due to liquid shear and abrasion due to collisions of particles were considered as possible mechanisms of biomass detachment in liquid fluidized beds. A dimensional analysis technique allowed the identification of the significant parameters affecting the process. The influence of these parameters was established on a lab-scale reactor. An empirical model was proposed to correlate the experimental data and to analyze the effect of some characteristic quantities, such as particle Reynolds number, biomass fraction, liquid shear stress and solid concentration, on the detachment rate. Detachment rate strongly increased with fluid velocity while, owing to modifications in biofilm structure and morphology during the biological growth, it slightly decreased with liquid shear stress. (C) 1997 IAWQ. Published by Elsevier Science Ltd
Modeling and experimental verification of physical and chemical processes during pyrolysis of a refuse-derived fuel
No full textA model for refuse-derived fuel (RDF) conventional pyrolysis in a fixed-bed reactor is presented. The model investigates the influence of the heat- and mass-transfer processes on the pyrolysis product yields. Solid degradation reactions have been modeled by assuming that the interactions between the main RDF components during pyrolysis are negligible and that the RDF pyrolysis behavior may be considered as the sum of the separate behaviors of ''primary reacting species''. The model accounts for conductive and convective heat transfer within the solid matrix and secondary tar-cracking-reactions, as well as for variability in physical properties and in the void fraction of the pyrolyzing material. Quite good agreement was found between model results and experimental data obtained for conventional pyrolysis of a RDF in a laboratory-scale fixed-bed reactor, The model is able to predict the temperature transients, the rate of gas generation, and the product final yields during conventional pyrolysis of RDF
THE ESTIMATION OF THE SOLID SIZE AND DENSITY IN LIQUID FLUIDIZED-BED BIOLOGICAL REACTORS
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