Experimental study of humidity influence on triboelectric charging of particle-laden duct flows

TL;DR

This study experimentally examines how ambient humidity affects electrostatic charging of particles in duct flows, revealing a non-linear relationship that impacts industrial safety.

Contribution

It provides new experimental data on humidity's effect on triboelectric charging in gas-solid flows, highlighting the complex influence of environmental conditions.

Findings

Electrostatic charge increases then decreases with humidity.

Charge levels depend on humidity in a non-linear manner.

Results inform safety protocols for pneumatic conveying.

Abstract

Electrostatic charge on powders arises during pneumatic transport due to particle-particle and particle-surface interactions via triboelectrification. This is a potential threat to the safety of industrial productions and the source of numerous fires and dust explosions in the past. Triboelectric charges are affected by environmental conditions, such as ambient temperature and relative humidity. In this work, we experimentally investigated the influence of ambient humidity on the particle charge of gas-solid flows in a square-shaped duct. Monodisperse PMMA particles are fed into a fully developed airflow in a PMMA duct and then pass through a metallic duct section. The charge of particles is measured at the outlet of the metallic duct via a Faraday cup. By measuring the electrostatic charge under various environmental conditions, we observed that the electrostatic charge first increases with the humidity and then decreases when the humidity becomes higher.