Synthesis of large-scale multi-stream heat exchanger networks using a stepwise optimization method

•A stepwise method for synthesizing large-scale MSHENs is proposed.•The pseudo-temperature diagram approach is employed in the presented method.•Several heuristic strategies for synthesizing sub-networks are proposed.•A hybrid algorithm combined SA and GA is used for the optimization.•The results obtained by the proposed method are better than those of previous paper.

In this paper, an efficient stepwise approach is presented for synthesizing large-scale multi-stream heat exchanger networks (MSHENs). The proposed approach employs the pseudo-temperature enthalpy diagram method to gain an initial network. In the next stage, several heuristic strategies are raised to conduct the selection and mergence of enthalpy intervals. The sub-networks are re-designed in the merged intervals based on the introduced strategies to disconnect the heat exchanger loops caused by involving too many intervals in the initial networks. A corresponding mathematical model is established with the objective of minimum total annual cost (TAC), and the simulated annealing and genetic algorithm (SA/GA) is adopted for the optimization. Two cases taken from literatures are studied to illustrate the effectiveness of the proposed method on solving MSHEN synthesis problems. The results obtained are better than those of previous paper and have shown an excellent performance of the multi-stream heat exchanger.