Optimal Molecular Design of Low-Temperature Organic Fluids under Uncertain Conditions

Computer-aided molecular design as a mixed-integer nonlinear programming problem under uncertainty in group contribution parameters has been addressed. A set of new low-temperature organic compounds, for heat recovery purposes, was obtained by solving the mixed-integer nonlinear programming problem with nominal values from a previous work. Monte Carlo simulations with Latin hypercube sampling were carried out to asses the effect of uncertain group contributions on thermo-physical properties. Furthermore, a set-based robust counterpart was formulated by taking into account uncertainty only in linear constraints. The results show that even small uncertainty in group contribution parameters can lead to significant variations in thermo-physical properties of the compounds analyzed. Therefore, it is necessary to consider uncertainty in the Computer-aided molecular design formulation. Solutions of the robust counterpart became more conservative as the uncertainty set size increased, producing organic compounds different from the nominal case.