Flashing calculations

[CMRM]

I'm trying to calculate the estimated flow rate of 1000psi saturated water through an orifice through which water discharges to the atmospheric pressure. Since flash evaporation occurs in this process I really don't know how to raise the problem.

 

[Latexman]

The solutions to two processes are needed. The rate process, or the fluid flow part of the problem (mass balance), and the state process, or the thermodynamic part of the problem (energy balance), needs to be solved and in agreement for a correct answer. Most first year thermodynamic texts would call your application "Throttling". Throttling is assumed to be adiabatic, so [Δ]H = 0.

If the temperature and dynamic pressure of the water upstream and in the throat of the orifice results in the water being only 1 phase (i.e. liquid), then most first year fluid mechanics texts cover single phase flow through an orifice pretty well.

If the temperature and dynamic pressure of the water upstream and in the throat of the orifice results in the water going into two phases, then you need to consult more sophisticated references, but I won't get into this until we get some feedback from you.


Good luck,
Latexman

 

[mbeychok]

CMRM:

It would be most useful for you to read the many papers by Hans Fauske on the flashing of saturated (or sub-cooled) liquids through equiment leaks. One such paper is:

Fauske, Hans K., "Flashing Flows: Some Guidelines For Emergency Releases", Plant/Operations Progress, July 1985

If you cannot find Fauske's papers, then you can purchase copies from this website:

http://www3.interscience.wiley.com/...cksearch&WISindexid1=WISall&WISsearch1=Fauske

Milton Beychok
(Visit me at www.air-dispersion.com)
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