Non-structural model of heat exchanger network: Modeling and optimization

Abstract

Simultaneous synthesis of heat exchanger network (HEN) is an indispensable strategy to improve energy efficiency and realize high techno-economic performances. The structural models that involve a stage-wise superstructure have some limitations concerning the global optimization for the HEN, including the flexibility of configurations and computational efficiency of synthesis methods. Therefore, a novel non-structural model (NSM) is proposed in this work for the simultaneous synthesis of the HEN. Firstly, the concept of a non-structural HEN configuration is described based on an analysis of the drawbacks of structural models. Then, the mathematical formulation of the NSM is provided. Finally, a general implementation method is proposed to realize the simultaneous synthesis of an NSM-based HEN and make it a feasible synthesis method. Six medium and large scale case studies are used to demonstrate the flexibility of configurations in the proposed model and its performance concerning the global optimization of HEN synthesis using a random walk algorithm with compulsive evolution. The combination of the NSM and the heuristic method has led to better optimal solutions than those that exclude the stream splits as published in previous works, achieving high quality and efficiency in the synthesis of HEN problems.