5.3: TQCEN

TOCGroup 5TQCELTQCENLGroup 1A-ZGroup 5


Use TQCEN to calculate the equilibrium, taking results from the previous equilibrium calculation as initial estimates

Added for ChemApp version 5.0.0



C: tqcen(option,indexp,indexc,vals,&noerr);

Pascal: tqcen(option,indexp,indexc,vals,noerr);

Basic: Call tqcen(option,indexp,indexc,vals,noerr)

Name Type Value set on call or returned
OPTION CHARACTER Set to a string as shown in Table 16
INDEXP INTEGER Set to the index number for a phase, if necessary
INDEXC INTEGER Set to the index number for a constituent, if necessary
VALS Array of 2 of
Set to an initial estimate of the target variable, or the lower and upper limits of an incoming amount, if necessary
NOERR INTEGER Returns an error number

Once an equilibrium has been calculated with TQCE or TQCEL, subsequent equilibria can be executed using TQCEN or TQCENL. When the two latter subroutines are called, results from the previous equilibrium calculation are used as initial estimates. This will result in a noticable increase of the computational efficiency, especially when the current settings of global conditions or streams are close to those of the previous calculation.

An error message (516) will result if the status of a phase constituent or a phase has been modified since the last executed phase equilibrium. Thus, after a call to TQCEN, the application programmer is advised to check NOERR for this value, and recalculate the equilibrium using TQCE if it equals 516.

If convergence would fail because of poor initial estimates, then the calculation will be automatically repeated with initial estimates produced by ChemApp.

For a description of the parameters and constraints, see TQCE.

See also




ChemApp Programmer's Manual, Edition 3.6© GTT-Technologies, 2003