Measurement and Analysis of multiple distribution of tribo-charge for a mixture of particles in gas-solids pipe flow

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The tribo-charging of particles in gas-solids pipe flow has been studied both theoretically and experimentally. A model for the particle charging has been presented, which is based on the charge transfer caused by particle impact on the wall surface and takes into account three probability density functions, i.e. (i) the number of collisions of a particle with the wall, (ii) initial particle charge, and (iii) the impact charging factor characterizing the transferred charge. These functions individually affect the electrostatic charge distribution, and hence key parameters on the particle electrification can be determined from the charge distribution. To verify the model, a system for measuring particle charge distribution has been constructed and the relevant experiments have been carried out using positively charged particles and negatively charged particles. It was found that the experimental results were in agreement with the theoretical ones, and by analyzing the values of the key parameters determined from the experimental data, the states of the particle charging were evaluated quantitatively. Furthermore, bipolar charge distributions were measured using a mixture of powders, showing that the charge distributions in a dilute phase transport system could be explained by the linear additivity of the charge distribution of each powder. It was also found that the particle charge can be controlled by the arrangement of the pipes made of different materials. In the present research, the system to analyze and control the particle charging was constructed.