Channel size Cross-flow velocity Reynolds number Cleanability Surface area to volume ratio Liquid hold-up Energy consumption
Tubular Large 2-6 m/s >104 Easy to clean (Membrane replacement is simple) Low High High
Hollow fibre Narrow 0.5-2.5 m/s 500-3000 Easy to clean (high membrane cost) High Low Low
Spiral wound Narrow 0.5-1.5 m/s 500-1000 Reasonably economic (membrane can collapse) High Low Low
Flat sheet Open/ narrow 2-3 m/s >104 Easy to clean (Membrane replacement is simple) Low moderate moderate
Vibrating Membrane Open/ Narrow 2-3 m/s >104 Easy to clean but Membrane replacement is difficult Low moderate High
Table 1: The characteristics of cross-flow module configurations.