The critical particle size model was developed through analyzing the forces acting on a single particle with axial

radial and circumferential directions considered.The effects of feed temperature

cross-flow velocity and permeate flux on the critical particle size were investigated theoretically and experimentally

and the mechanism of particle deposition was discussed.Both simulation and measured results show that the membrane thickness becomes larger with the decrease of feed temperature and increase of trans-membrane pressure difference

and smaller with the increase of cross-flow velocity.Because of the net gravity

there exists a dynamic layer of non-uniform thickness along the circumference direction in the horizontal tube.This non-uniformity can be reduced evidently as the cross-velocity increases.The model calculation is in good agreement with the experimental results.