Equilibrium charge and triboelectric coefficient of spheres in a rotating container--颗粒学报PARTICUOLOGY

Hu, J., Liang, C., Zhou, Q., & Ma, J. (2022). Equilibrium charge and triboelectric coefficient of spheres in a rotating container. Particuology, 63, 103-111. https://doi.org/10.1016/j.partic.2021.03.004

Equilibrium charge and triboelectric coefficient of spheres in a rotating container

Jiawei Hu, Cai Liang ^*, Qun Zhou, Jiliang Ma

Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China

10.1016/j.partic.2021.03.004

Volume 63, April 2022, Pages 103-111

Received 27 October 2020, Revised 10 March 2021, Accepted 12 March 2021, Available online 20 April 2021, Version of Record 18 November 2021.

E-mail: liangc@seu.edu.cn

Highlights

• Equilibrium charge and triboelectric coefficient were proposed to characterize the tribo-charging process.

• Effects of material type, rotation speed and relative humidity on contact electrification were studied.

• Charge relaxation constant and charge generation constant were compared.

Abstract

Contact electrification occurs in many granular material systems due to particle-particle and particle-wall contacts. In this paper, we used a simple device to characterize the electrification of different spheres in a rotating spherical container. The charge of the spheres was quantified by a Faraday cup after rotating for various time and the disperse behaviors of charged spheres were recorded by a camera. The effects of the rotational time, sphere size, rotational speed, sphere material, and relative humidity on the equilibrium charge and triboelectric coefficient were analyzed. The results show that the equilibrium surface charge density is independent of the sphere size and the rotating speed, whereas the larger rotating speed enhances the triboelectric coefficient. It is also shown that charge relaxation constants are two orders of magnitude lower than the charge generation constants for all spheres at a low relative humidity. The increase of water molecules in the air was found to result in the decline of charge generation constant and the rise of charge relaxation constant, which together cause the decrease of the equilibrium surface charge density.

Graphical abstract

Keywords

Particle charging; Equilibrium charge; Charge relaxation; Charge generation; Electrostatics

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