# Pressure drop problem (using the darcy law)

1. Jul 24, 2012

### sifr

1. The problem statement, all variables and given/known data

Estimate the pressure drop in a tower packed with porous support. This tower is an integral part of a water oxygenation system and will need to operate over extended periods without cleaning.

From the following data estimate the pressure drop you expect to see on start-up

Diamter = 1.5m
Height = 3m
Support size = 0.004m

2. Relevant equations

Δp = (uμh)/β

u is liquid velocity
μ is liquid viscosity (I.e. water)
β is bead permitivitty (I.e the support)

3. The attempt at a solution

I have had no problem calculating β and got 4.9 x 10^-9m
Where I get stuck is finding 'u'

for these problems I usually use the formula u = Q/A
Volumetric flow rate over cross sectional area - however in this instance there is no information about the volumetric flow rate

Should I assume a volumetric flow rate? Or is there a way to calculate it from the above information? (sometimes they give something away in the wording such as 'start up' - not sure what I should take from that)

Are there any other equations I can use? This is a 15 mark question so I'm assuming there's a bit of calculation that needs to go into it.