## Two Phase Choked Flow

## Two Phase Choked Flow

(OP)

I am currently working on calculating the mass flowrate for two different nozzles from two high pressure sources (400 psi & 850 psi boiler blowdown to an atmospheric tank). Having not really done any calculating (due to lack of information) I can only assume these flows will be choked, and due to the pressure drop the fluid should be flashing in the pipe. Does anyone have any experience calculating two phase choked flow? I don't have any access to software (becides excel ;) ), but library (text) references can be aquired. As always, any help is greatly appreciated!

jproj

jproj

## RE: Two Phase Choked Flow

The two eqns are easily handled by Excel, but pretty cumbersome to do by hand.

Thanks!

Pete

pjchandl@prou.com

## RE: Two Phase Choked Flow

## RE: Two Phase Choked Flow

To be specific, I am trying to size the steam and liquid outlet lines on the blowdown tank. To get this flow, we need to know the inlet flow from blowdown inlets. The inlet flows are to be based on choked flow from a 2" nozzle (850# blowdown), and a 2½" (400# blowdown), both saturated liquid at the boiler outlet.

Unfortunately, this is in the "design / build" phase (quick ship) and (as luck would have it) our customer (the design engineer for the job) is unwilling to tell us how to calculate this flow (they don't know the flow or haven't calculated it, but they specify the blowdown tank size... go figure!).

If anyone knows of any sources for information, I would greatly appreciate the help!

jproj

P.S. Pete: I tried searching on James or James equation, but I didn't find anything. If you could point me to where I could find it, I would be much appreciative!

Thanks!!!

## RE: Two Phase Choked Flow

Actually, after giving it some more thought, I think you may be able to determine the blowdwon flow rates given the nozzle sizes. The Crane manual (Flow of Fluids Through Valves, Fittings, and Pipes) covers calculation of flow of liquids through nozzles and orifices. You may need some more data like the ID of the blowdown lines, but it looks pretty straightforward.