DILUTE PHASE PNEUMATIC CONVEYING IN A HORIZONTAL PIPE: EFFECT OF RESTITUTION COEFFICIENT AND SPECULARITY COEFFICIENT

Dilute-phase gas-solid flow (i.e., pneumatic conveying) in a horizontal pipe has been solved in the present research work using Euler-Euler modeling, or the two fluid modeling approach. In Euler-Euler modeling, the gas and solid phases are both treated as a continuum. It was observed that particles settle in the pipe wall and do not distribute in the whole cross section of the pipe as expected by neglecting particle-particle collisions. For radial dispersion of the particles in the horizontal gas-solid flow, it is essential to consider collisions along with the lift force. The value of the numerical parameter specularity coefficient strongly affected the two-phase pressure drop prediction, which was chosen correctly by comparing it with existing experimental data. The major findings of the present work are that the pressure drop increased with the gas-phase Reynolds number and solid volume fraction. However, with respect to the particle diameter, the pressure drop first increased, reached a maximum, and then decreased. Solid particles in the range of 35-200 mu m and the solid volume fraction in the range of 1%-10% were considered in the present research work. Also, the computed data for the pressure drop were compared with the existing correlations for the pressure drop available in the literature and it was found that the Yang and Michaelides correlations are qualitatively in good agreement with the computed data within an error of +/- 30%.