A practical multi-period heat exchanger network (HEN) design is required to satisfy not only the operating requirements in several discrete sub-periods

but also the flexibility requirements in all sub-periods that help to compensate the potential fluctuations of the parameters in each sub-period. However

the problem of overdesign arise in most cases where the heat transfer areas are determined by increasing the margin or using the maximum area concept during the multi-period HEN design. These factors will lead to a waste of resource and capital. To address these problems

a method of multi-period HEN design considering overdesign control is proposed by taking both the requirements of multi-period operation and single period flexibility into account. In the proposed method

an initial multi-period HEN is first obtained by the single period HEN optimization. A HEN modification model

on the basis of stage-wise superstructure model and flexibility index model

is then developed and solved to determine the optimal modifications of the initial multi-period HEN in each sub-period. The final multi-period HEN is thus finished by combing the initial multi-period HEN and the corresponding modifications. The application and effectiveness of the proposed method are finally verified through a comparison of the results in this work and those in literature.