Near Independent Subnetworks in Heat Exchanger Network Design

A minimum number of matches in a heat exchanger network (HEN) can be achieved by maximizing the number of independent subnetworks. The mixed-integer linear programming (MILP) transshipment model of Papoulias and Grossmann (Comput. Chem. Eng. 1983, 7, 707) allows for reaching the maximum number of perfectly balanced subnetworks, i.e., all streams are forced to reach given outlet temperatures. We have developed a method that maximizes the number of near-independent subnetworks, in which the streams achieve a certain specified outlet temperature within a tolerance. This conforms better to an industrial scenario and potentially generates a higher number of subnetworks. The approach is based on a MILP transshipment model formulation solved in a recursive procedure. The method ensures the minimal number of matches and minimal deviations from the nominal outlet temperatures.