Eulerian modeling of mono-disperse gas–particle flow with electrostatic forces
Résumé
Due to triboelectric charging, the solid phase in gas–particle flows can become electrically charged, which induces an electrical interaction between all the particles in the system. Because this force decays very rapidly, many current models neglect the contribution of the electrostatic interaction between the particles. Nevertheless, the impact that this force can have in many industrial configurations is well documented. In this work an Eulerian–Eulerian model for gas–particle flow is proposed in order to take into consideration the electrostatic interaction between the particles. We use the kinetic theory of granular flows to derive the transport equation for the electrical charge for dense gas–particle systems. We show that the electric charge transport equation can be derived without presuming the for the particle charge distribution. In order to close the collision integrals in the Chapman–Enskog equation, we proposed a linear model for the charge-velocity correlation. The model was tested in a 3 dimensional periodic box. The results shows that the dispersion phenomenon have two contributions: a kinetic dispersion due to the random motion of particles (predominant in dilute systems) and collisional dispersion due to the electron transfer during a particle-particle collision (predominant in dense systems). Another effect that contributes to the particle transfer is the triboconductivity effect, which is the motion of electrons following the global electric potential difference. The dispersion and triboconductivity characteristic times where calculated, and the analysis shows that, in dense systems, the two effects are comparable if the dispersion characteristic length is equal to the particle diameter.
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