Structure and Area Optimization of Flexible Heat Exchanger Networks

A novel method is outlined for flexible heat exchanger network synthesis including nonconvex problems. The presented method is sequentially implemented by two main steps: structure synthesis and area optimization; nevertheless, the optimization of heat exchanger areas can still react on the structure to gain the global optimal solution. The structure is initially synthesized at the nominal operating point and renewed by the topological union with the structure of the critical point and the improved heat transfer loops disconnection strategy. For area optimization, an iterative approach with strong robustness is proposed based on the influences of heat exchanger areas on flexibility index and total annual cost, respectively. The direction matrix method is employed to provide the operational flexibility of the network and the critical operating point. Two examples with nonconvex feasible regions have been studied, and the results well demonstrate the effectiveness of the proposed approach