The C-Routines are the core of the process synthesis software. They include functions that can be grouped in three categories:
- Thermodynamics and numerics
The implemented thermodynamic models allow for all kinds of property calculations. While the repertoire of equation of state and activity coefficient models is restricted, the most common models, such as NRTL, UNIQUAC, UNIFAC, Redlich-Kwong, Peng-Robinson, etc. are included. A set of numerical routines, including linear and nonlinear system solvers, is available, e.g. for the calculation of phase equilibrium (VLE, VLLE, LLE).
- System analysis
Beside different routines for the calculation of azeotropes and a topologcial consistency check, routines for the calculation of residue curves (RC), distillation lines (DL) and pinch lines (PL) are available. The latter are of vital importance for the implemented shortcut methods. The calculation is based on an efficient homotopy continuation approach and special test functions to detect possible bifurcations of the solution branches. Based on the RC, DL and PL, additional routines facilitate the calculation of different concepts for the approximation of distillation boundaries by means of simple distillation boundaries (SDB), total reflux boundaries (TRB) and the so called pitchfork distillation boundaries (PDB).
- Separation analysis
Based on the routines for the calculation of the RC, DL and PL, as well as the different distillation boundary concepts additional routines aim at the determination of split feasibility. Besides that a multitude of shortcut methods for the determination of the minimum energy demand of distillation-based separations is available, all of which are based on publications of the AVT.PT.