Programming issues

Both TQSTSC (Get – Stoichiometry – System – Component) and TQSTPC (Get – Stoichiometry – Phase – Constituent) return a molecular mass via the parameter WMASS. If you did not change the mass unit using TQCSU (Change – System – Unit), it remains set to the default unit, which is ‘mol’. The molecular mass is […]

If an error occurs (error no. 103 or 102) while reading the thermodynamic data-file using TQRFIL (Read – File), the reason is typically one of the following: The file has not been opened properly.  This can especially happen when the subroutine TQOPEN (Open – File) is used (i.e. when programming in languages other than FORTRAN)

If ChemApp indicates that it cannot calculate an equilibrium, typically returning error numbers 701 or 702 after a call to TQCE (Calculate – Equilibrium) or TQCEL (Calculate – Equilibrium – List – Results), check the conditions which are active for the equilibrium calculation in question using TQSHOW (Show – Present – Settings). Then check the

Both TQGETR (Get – Results) and TQGDPC (Get – Thermodynamic – Data – Phase – Constituent) allow you to retrieve the values for these thermodynamic functions for phase constituents. The difference is that TQGETR retrieves these values for the previously calculated equilibrium state. The values retrieved with TQGDPC, on the other hand, have nothing to do

The answer in short: Perform a target calculation with volume as target and pressure as target variable instead. When calculations are made under constant product volume by using the option ‘VT’ of the subroutines TQSETC (Set – Equilibrium – Condition) or TQSTEC (Set – Equilibrium – Condition – When – Stream – Input), ChemApp will

For users of ChemApp versions prior to 3.2.0: The values returned by TQSTXP (Get – Thermodynamic – Property – Of – A – Stream) always refer to the last calculated equilibrium state. If TQSTXP is called before the first equilibrium calculation has been performed using TQCE (Calculate – Equilibrium) or TQMAP (Calculate – One –

A set of subroutines to do exactly that will be included in the next release of ChemApp/ChemApp light (version 3.3.x).