Euler/Lagrange computations of pneumatic conveying in a horizontal channel with different wall roughness

The present study is related to the particle behaviour and the pressure drop in a particle-laden six meter long horizontal channel with rectangular cross-section from both experimental and numerical perspectives. Experiments and calculations are carried out for different spherical glass beads with diameters between 60 and 625 μm and mass loadings up to 1.0 (kg particles/kg gas). Additionally, stainless steel walls with different wall roughness are considered. In all experiments the air volume flow rate is constant in order to maintain a fixed gas average velocity of 20 m/s. As a result, the pressure drop in the channel is strongly influenced by wall roughness. Higher wall roughness implies higher pressure drop because of the increase in wall collision frequency, whereby momentum is extracted from the fluid due to two-way coupling. The numerical computations were performed by the Euler/Lagrange approach accounting for two-way and four-way coupling. For the calculation of the particle motion all relevant forces (i.e. drag, transverse lift and gravity), inter-particle collisions and wall collisions with wall roughness were considered. The agreement of the computations with the experiments was found to be very good for the gas and particle velocities as well as the pressure drop.

Graphical abstractThe Euler/Lagrange approach was applied to pneumatic conveying in a narrow horizontal channel. The results on velocities of both phases and pressure drop were compared with measurements. Variations of particle size, mass loading and degree of wall roughness were realised. The agreement of velocity profiles was found to be reasonable and the increase of pressure drop by the particles with increasing wall roughness was captured very well using a stochastic wall roughness model and accounting for inter-particle collisions (see Figure).Figure optionsDownload full-size imageDownload as PowerPoint slide