Isentropic Flash Calculations
Isentropic Flash Calculations
(OP)
Hi guys,
I'm working on some two-phase flow applications, attempting to use API 520's omega method. The methods call out an isentropic/adiabatic flash calculation to determine the system specific volume. Unfortunately I don't have access to ASPEN or similar software.
I tried searching the forums and found lots of references to process simulators and using Prode Properties (which I have but am not very familiar with), but I can't seem to find any source that shows the equations for this calculation.
Does anyone have a source/reference that shows the steps for doing the flash calculations? I also hesitate to use Prode Properties when I'm unfamiliar with it; is there a good guide to using it anywhere?
I'm working on some two-phase flow applications, attempting to use API 520's omega method. The methods call out an isentropic/adiabatic flash calculation to determine the system specific volume. Unfortunately I don't have access to ASPEN or similar software.
I tried searching the forums and found lots of references to process simulators and using Prode Properties (which I have but am not very familiar with), but I can't seem to find any source that shows the equations for this calculation.
Does anyone have a source/reference that shows the steps for doing the flash calculations? I also hesitate to use Prode Properties when I'm unfamiliar with it; is there a good guide to using it anywhere?





RE: Isentropic Flash Calculations
This is the simple, vapor only venting derivation for a PSV. Two-phase is more complex, but it's derivation and examples can be found if your Google-fu is strong.
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
RE: Isentropic Flash Calculations
http://www.prode.com/en/properties.htm
RE: Isentropic Flash Calculations
Good luck,
Latexman
To a ChE, the glass is always full - 1/2 air and 1/2 water.
RE: Isentropic Flash Calculations
RE: Isentropic Flash Calculations
in this forum you can find several references to Prode Properties since the library includes several equilibrium (HEM) and non-equilibrium (HNE) models,
there is an Excel page with VBA code for API HEM (posted by PaoloPemi) but (as far as I know) the procedures included in the library calculate the speed of sound (critical flow) with different models for equilibrium and non-equilibrium cases,
as said by chicopee in some cases (for example, pure fluids) you can utilize a mollier chart or a table of values, while for mixtures you need to solve phase equilibria.
RE: Isentropic Flash Calculations
I prefer PRODE for these calc's but you can use another simulator as well,
however, as library, Prode offers several advantages when working with Excel or similar applications (while a simulator is more suitable for solving complex plants).