ABSTRACT
The steady-state and volumetric flexibility indices have been computed for the membrane modules discussed in several case studies. In some cases, it is beneficial to consider the volumetric flexibility index (FIv) as an alternative metric. To demonstrate the merits of this multicriteria approach, steady-state and volumetric flexibility analyses are applied to the designs of two different types of realistic systems: the membrane module and the heat exchanger network (HEN). The boundary points of the feasible region, which are accurately identified in volumetric flexibility analysis, could be adopted for pinpointing the most constrained segment of the active constraint in steady-state flexibility analysis. Moreover, instead of the single set of nominal conditions adopted in the traditional ad hoc approach, many other options may be considered because any operable point within the feasible region can be chosen for design.
