Gas-solid flows with tribocharging

In this study, we seek to shed light on dynamics of tribo-electrically charged particles in granular materials through a combination of computational modelling and experiments. Tribocharging is a process by which two materials exchange electric charge upon mechanical contact; it has been observed in many industrial applications such as fluidised beds, pneumatic conveying pipes and silo flows. To study how tribocharging affects hydrodynamics of granular materials, we develop Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) simulation platform, where the locally-averaged equations of motion for the fluid phase are solved in a Eulerian framework and the particles are tracked in a Lagrangian fashion by solving Newton’s laws of motion. In this approach, we use a finite-volume based particle-particle and particle-mesh type Poisson solver for the electric field and a tribocharging model that accounts for the charging tendency of particles captured by effective work function difference between the contacting surfaces and the electrical field at contact. We then undertake fluidized bed experiments and measure average charge on polyethylene particles at different controlled humidity conditions. Subsequently, we perform CFD-DEM simulations of the same flow configuration and show that the predicted charge values are in a good agreement with experimental data.