[oj.bulmer]

Hello

I was wondering what is best way to specify the inlet boundary condition for bubble columns with ring sparger.

The options are:

1. Determine superficial air velocity by experimental measurement, assume a suitable volume fraction at sparger inlet (generally 0.3) and use this to calculate inlet gas velocity by following relation.
   
   ...........( being inlet gas volume fraction)
   
   
2. Calculate ellispsoidal regime settling velocity and use it as a superficial velocity, to calculate the inlet velocity as mentioned in point #1. This avoids the tedious and more-than-often impractical measurement of gas superficial velocity
   
   
3. Specify inlet volume fraction (~0.3) and mass flow rate that is known. This seems a lot easier, especially when it comes to mass imbalance calculations at degassing outlet at top.

In literature I have reviewed so far, option 1 seems mostly ( rather universally) popular, though difficult to implement in my case due to lack of availability of data. Option 2 is theoretical simplification and discards any geometrical influence and there is no evidence of this being appropriate in the literature. Option 3 seems so obvious choice, but I am yet to find a publication that mentions the use of mass flow rate at inlet. Quite surprising.

Any ideas about which may be the best way?

Regards
OJ