Modeling Study on the Pressure Drop and Characteristic Velocity of the Pneumatic Logistics Transmission System

In this paper, experiments and theoretical analysis were carried out to develop the pressure drop model and to predict characteristic velocities of the pneumatic logistics transmission system. First, the pressure drop model was developed by taking into account both structure properties of the conveying system and contributions of both gas and solid phases. In particular, the gas-phase contribution considers four terms of the gas passing through the various parts of the transfer bottle and the pipe, and the solid-phase contribution should be considered only when the transfer bottle is in the motion state. Second, a model to predict the transfer bottle velocity was developed based on analyzing the pressure state in the gas chamber in the front of the transfer bottle. Necessary model parameters including gas and solid friction coefficients were then determined by conducting conveying experiments. This allows us to predict the pressure drop and the characteristic velocity of the pneumatic logistics transmission system. Model predictions agree well with experiments, by giving errors mostly smaller than ±10% for the system pressure drop. The critical gas velocity according to the initial motion of the transfer bottle and transfer bottle velocities at various conditions were successfully predicted as well.