Heat exchanger networks synthesis considering the rigorous equipment design and distinct parameters for capital cost estimation

In the present paper, a novel bi-level approach for the optimal synthesis of HENs is presented. A new capital cost parameter is iteratively updated in the capital cost function based on the shell and tube heat exchangers detailed design considering the shell diameter, tube length, the area as well as the other parameters needed to calculate a total cost correction factor, in such a way that the heat exchangers in the HEN have different capital cost parameters. At the outer level, a mixed-integer nonlinear programming (MINLP) model is proposed for the HEN synthesis. In the inner level, another MINLP model is used to rigorously design the shell and tube heat exchangers using the Bell-Delaware method as the HEN is being synthesized. Two case studies are performed, and considerable differences in the final HEN were observed when compared to those obtained using the same parameters in the capital cost function for all heat exchangers in the HEN. The results show that this strategy can provide more realistic solutions for costing than those presented previously in the literature.