Optimal design of controllable heat-exchanger networks under multi-directional resiliency-target constraints

Controllable design of heat exchanger networks is formulated as constrained nonlinear optimization problem. The objective of this new method is to find the individual exchanger areas and bypass fractions which minimize the total annualized cost (or the total area) of the given heat exchanger network structure and, at the same time, to satisfy all the target temperature constraints (hard or soft) for a set of disturbances predefined in all possible directions. This is achieved by solving only one constrained optimization problem which considers the exchanger model equations (heat transfer and mixing) and constraints (resiliency index, heat load and the minimum approach temperature) simultaneously for all possible predefined disturbance directions. With the proposed method, a retrofit design satisfying given set of resiliency-target constraints of a heat exchanger network at minimum cost is accomplished.