Souders Brown equation given by$,$ U $=$ Kv $($l $-$ v$)/$v$,$ is used for the calculation of the $\_\_\_\_\_\_\_\_\_$ in a continuous distillation column.

Diameter of the bubble cap column

Diameter of the sieve plate column

Tray pressure drop

Residence time in the downcomer for the disengagement of entrained vapour