How to select equilibrium calculation methods

Moderator: jasper

How to select equilibrium calculation methods

Postby arvind.prasad » 18 April 2017, 02:32

Dear Jasper,
I have a mixture of Nitrogen, Hydrogen and ammonia. The thermodynamics package selected is Peng Robinson Equation of state. If I try to find the temperature for liqufaction, clicking stream>Phase Fraction>vapor fraction flash, for 20 percent vapor, a window pops up. The warning is Calc Equilibrium Failed: Equilibrium Flash Failed. I receive warnings in the log. Can we change the flash methods? I guess TP flash would solve the problem
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Re: How to select equilibrium calculation methods

Postby jasper » 18 April 2017, 07:13

Please select Plot, Create, Temperature plot, and select stream 1, vapor fraction, phase vapor, T = 0 to 500 K (not C).

You will see that there where the TP flash actually solves, the vapor fraction always exceeds 85%, which is not surprising when with about 70% hydrogen.

The flash you are asking for has no solution with the selected model and overall composition.
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Re: How to select equilibrium calculation methods

Postby arvind.prasad » 18 April 2017, 13:33

Thanks Jasper.
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