The transport of a fine powder under an extremely dense phase condition was tried using a progressive cavity pump that is a type of constant-volume pump.
When the void fraction of the powder in the transport pipe is larger than that of loose packing, the pressure drop in the powder transport can be estimated by previous theoretical equations using the dynamic internal and wall-friction coefficient. However, if the void fraction of a powder in the pipe is lower than that of the loose packing condition, the pressure drop increases suddenly and can't be estimated by the previous theory. The reason the experimental result is different from the value calculated by the previous theory is that the pressure drop depends on the particle-wall friction loss by the powder pressure. Therefore, we try to estimate the pressure drop in the pipe using the powder pressure acting on the pipe wall the same way as the estimation of that in a bin. The calculated value based on our method shows good agreement with the experimental data.
