Statistical variation of characteristics of random packed beds of Raschig rings: The influence of the sample size (Open Access)--颗粒学报PARTICUOLOGY

Niegodajew, P., & Marek, M. (2021). Statistical variation of characteristics of random packed beds of Raschig rings: The influence of the sample size. Particuology, 56, 50-61. https://doi.org/10.1016/j.partic.2020.11.004

Statistical variation of characteristics of random packed beds of Raschig rings: The influence of the sample size (Open Access)

Paweł Niegodajew, Maciej Marek ^*

Czestochowa University of Technology, Department of Thermal Machinery, al. Armii Krajowej 21, 42-200 Czestochowa, Poland

10.1016/j.partic.2020.11.004

Volume 56, June 2021, Pages 50-61

Received 5 September 2020, Revised 19 October 2020, Accepted 11 November 2020, Available online 8 January 2021, Version of Record 8 March 2021.

E-mail: marekm@imc.pcz.czest.pl

Highlights

• Analysis of variation of bed structure between many realisations of packing is made.

• Variation of bed characteristics depends on the sample size and ordering effects.

• Orientation distribution of particles strongly depends on the sample size.

• Porosity distribution is well-reproducible, even for small beds.

Abstract

Many studies on random packed beds have been dedicated to local porosity (void fraction) or orientation distribution of particles. However, despite the random nature of the considered packings, very little attention has been devoted to examination whether the number of particles used in experiments/simulations is sufficiently large to get reproducible results. The reproducibility of the key packing parameters depends on the size of the population of particles (sample size) and ordering effects induced by the confining walls. This work investigates quantitatively the influence of the sample size on the statistical variation of the packed bed characteristics. Packed beds of Raschig rings were generated with a sequential algorithm and three column diameters were considered. It has been found that in the case of the orientation distribution the results depend strongly on the sample size, especially for slender columns, while the porosity profiles are well-reproducible characteristics even for relatively small packings of rings. Some complementary results for full cylinders are also included.

Graphical abstract

Keywords

Random packing; Raschig rings; Full cylinders; Particle orientation; Porosity; Reproducibility

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