The accuracy of fluidized-bed CFD predictions using the two-fluid model can be improved significantly, even when using coarse grids, by replacing the microscopic kinetic-theory-based closures with coarsegrained constitutive models. These coarse-grained constitutive relationships, called filtered models, account for the unresolved gas-particle structures (clusters and bubbles) via sub-grid corrections.Following the previous 2-D approaches of Igci et al.
Recebido em 8/3/07; aceito em 11/7/07; publicado na web em 19/12/07Knowledge of coal combustion kinetics is crucial for burner design. This work aims to contribute on this issue by determining the kinetics of a particular Brazilian bituminous coal. Non-isothermal thermogravimetry was applied for determining both the preexponential factor and the activation energy. Coal samples of 10 mg and 775 μm mean size were used in synthetic air atmospheres (21 % O 2 ). Heating rates from 10 to 50 o C/min were applied until the temperature reached 850 o C, which was kept constant until burnout. The activation energy for the primary and the secondary combustion resulted, respectively, in 135.1 kJ/mol and 85.1 kJ/mol.
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