How easy the solution of an MINLP model of a superstructure is usually analyzed according to the shape (linearity, convexity, relaxation, etc) of the equations, see e.g. Grossmann (1996). Here relations between the (super)structures and their MINLP representation are studied. In order to analyze this relation, we have defined ideal MINLP and binarily minimal MINLP representations. The effect of ideality and the number of binary variables on the solution time are compared on test examples. The first example is the synthesis problem of Kocis and Grossmann (1987). An ideal and, in the same time, binarily minimal MINLP representation has been constructed and solved. The second example is the membrane train of an industrial ethanol dehydration problem (Lelkes et al., 2000). The representations, solved on a Sun Sparc station using GAMS DICOPT++ solver, are compared according to the maximal size of solvable problems.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Computer Science Applications