A novel optimization framework for designing multi-stream compact heat exchangers and associated network

Despite the performance gains of heat exchangers by thermal-hydraulic optimization, many design approaches suffer from a long process of trial-and-error, limited practical problem formulation and poor robustness. This paper addresses those challenges and develops an optimization framework for designing multi-stream compact heat exchangers. The optimization framework consists of a multi-stream matching organization design with Pinch analysis principles on the heat exchanger network, fin selection and relevant layer pattern using multi-objective algorithm for the thermal-hydraulic modeling, and a field synergy optimization analysis for the temperature field of exchanger. There are compatible with each other by the mutual restriction of design parameters and the process requirements. Finally, by means of a segmented differential calculation, the designed temperature field of all the streams and layers can be obtained. Design capabilities of this optimization framework are investigated on two multi stream heat exchangers for cryogenic air separation processes. The optimization results are compared with traditional design methods, proving that this framework not only satisfies the specific energy requirement, but also to some extent improves the heat transfer efficiency and reduces the fluid resistance. The developed optimization framework provides a flexible and robust method for numerical simulation and optimization design of multi-stream heat exchangers. (C) 2017 Elsevier Ltd. All rights reserved.