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Licensed Unlicensed Requires Authentication Published by De Gruyter December 4, 2014

Numerical Analysis of Residence Time Distribution in Packed Bed Reactors with Irregular Particle Arrangements

Theodoros Atmakidis and Eugeny Y. Kenig


The computational fluid dynamics approach is applied to packed bed reactors with moderate tube-to-particle diameter ratios. In order to generate irregular particle arrangements within the reactors, a modified ballistic deposition method is used. While our previous studies were focused on pressure drop and mass transfer characteristics, the present paper uses the same framework to investigate the dispersion phenomena occurring in such reactors. Two different methods, namely the tracer and the post-processing method, are applied. The first method imitates the experimental procedure in which a non-diffusive tracer is injected into the packed bed. The residence time can be evaluated from the evolution of the tracer concentration. The second method is purely numerical and allows fast residence time estimation. Simulation results are successfully validated against experimental data from literature. The suggested numerical analysis is a valuable tool toward a deeper understanding of the fundamental transport phenomena in such reactors and, consequently, for the improvement of the packed bed performance.



Specific surface area, m2/m3


Dimensionless tracer concentration, –


Local tracer concentration, mol/m3


Cross-section-averaged tracer concentration, mol/m3


Total injected tracer concentration, mol/m3


Axial dispersion coefficient, m2/s


Molecular dispersion coefficient, m2/s


Diffusion coefficient, m2/s


Residence time distribution, 1/s


Particle diameter, m


Packed bed length, m


Peclet number, –


Molecular Peclet number, –


Reynolds number, –


Time, s


Local velocity, m/s


Superficial velocity, m/s


Dimensionless vertical coordinate, –


Vertical coordinate, m

Greek letters

Porosity of the packed bed, –


Dimensionless time, –


Tube-to-particle diameter ratio, –


Dynamic viscosity, kg/m s


Density, kg/m3


Second central moment of the RTD, s2


Dimensionless second central moment of the RTD, –


Local residence time, s


Mean residence time, s


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Published Online: 2014-12-4
Published in Print: 2015-3-1

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