Abstract
Pressure drop of a long packed granular bed is usually calculated by using the air velocity at the mid-length of bed because a decrease in pressure towards the bed outlet brings the expansion of air and therefore an increase in air flow velocity. However, for a long bed consisting of small particles with a low voidage at a high air velocity, the air pressure decreases so significantly that the prediction of pressure drop with the air velocity at the mid-length of the bed is no longer applicable. Consequently, the pressure drop has to be calculated in an integral manner by considering the air velocity increase across the bed. The present work estimated the error between the pressure drop predicted with the mid-length air velocity and that in an integral manner for various lengths of bed. As a result, it is shown that the pressure drops at various air velocities can be readily predicted when the pressure ratio at two locations in the bed is known at a given air velocity.
