DEM investigation of mixing indices in a ribbon mixer (Open Access)--颗粒学报PARTICUOLOGY

Jin, X., Chandratilleke, G. R., Wang, S., & Shen, Y. (2022). DEM investigation of mixing indices in a ribbon mixer. Particuology, 60, 37-47. https://doi.org/10.1016/j.partic.2021.03.005

DEM investigation of mixing indices in a ribbon mixer (Open Access)

Xin Jin, Ganga Rohana Chandratilleke, Shuai Wang, Yansong Shen ^*

School of Chemical Engineering, University of New South Wales, Sydney, NSW 2052, Australia

10.1016/j.partic.2021.03.005

Volume 60, January 2022, Pages 37-47

Received 14 July 2020, Revised 12 March 2021, Accepted 12 March 2021, Available online 11 April 2021, Version of Record 23 October 2021.

E-mail: ys.shen@unsw.edu.au

Highlights

• The accuracy of mixing indices in a cylindrical ribbon mixer is studied by DEM.

• The results of several mixing indices are compared at particle scale and macro-scale.

• Non-sample variance methods are used to compare against the sample variance methods.

• Lacey index is the most suitable index among the indices considered in this study.

Abstract

Mixing index is an important parameter to understand and assess the mixing state in various mixers including ribbon mixers, the typical food processing devices. Many mixing indices based on either sample variance methods or non-sample variance methods have been proposed and used in the past, however, they were not well compared in the literature to evaluate their accuracy of assessing the final mixing state. In this study, discrete element method (DEM) modelling is used to investigate and compare the accuracy of these mixing indices for mixing of uniform particles in a horizontal cylindrical ribbon mixer. The sample variance methods for mixing indices are first compared both at particle- and macro-scale levels. In addition, non-sample variance methods, namely entropy and non-sampling indices are compared against the results from the sample variance methods. The simulation results indicate that, among the indices considered in this study, Lacey index shows the most accurate results. The Lacey index is regarded to be the most suitable mixing index to evaluate the steady-state mixing state of the ribbon mixer in the real-time (or without stopping the impeller) at both the particle- and macro-scale levels. The study is useful for the selection of a proper mixing index for a specific mixture in a given mixer.

Graphical abstract

Keywords

DEM; Particle mixing; Mixing index; Ribbon mixer; Sample variance methods; Non-sample variance methods

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