I am modeling a humidication device in AspenPlus to control the relative humidity of a room. The device (please see the attached diagram for clarification) is intended to operate by introducing or retiring H2O from the inlet air stream in order to meet the required humidity set point. A DesigSpec is utilized to vary the amount of introduced/retired water. However, I need it to be able to change the manipulated variable depending on the specific case. For example:
IF Real Humidity< Humidity set point THEN Increase H2OIN & do not manipulate H2OOUT
IF Real Humidity>Humidity set point THEN Increase H2OOUT & do not manipulate H2OIN
I appreciate any contribution to overcome the problem.
Best regards
Hello Enrique,
Im not sure but, have you tried with a Calculator instead of a Design Spec? With a Calculator you can write more complex expressions (including conditional statements). Maybe you can write a FORTRAN subroutine which satisfies your needs. GLK!!
Regards
Hello Junior Lorenzo Llanes ,
I was precisely trying with a calculator as a work around. Yet, I am not sure it can actually perform the same calculation the DesignSpec would (I mean, the "mini-optimization" problem a DesignSpec solves).
Anyway, I will keep trying.
Thanks for your contribution!
You can use inline Fortran statements for the definition of the Variables in the Define Tab and in the Target definition on the Spec Tab.
Not sure if .LT. etc works. Its worth a trial!
Check online help "Rules for In-Line Fortran Statements"
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