Non-structural model for heat exchanger network synthesis allowing for stream splitting

Abstract

For more than three decades, heat exchanger network (HEN) synthesis has been primarily addressed by defining initial structures that embed different design alternatives, and near optimal HEN configurations are extracted from these structures during the optimization process. However, such initial structures are prone to missing necessary design alternatives and may require simplifying assumptions to ease the computational burden of optimization algorithms. This paper presents a non-structural model (NSM) for synthesis of HEN considering stream splitting and non-isothermal merging of branch streams. The model exhibits randomness in stream matching, generation and elimination by which potential matches are realized. Random walk algorithm with compulsive evolution is used for optimization of both integer variables (number of heat units) and continuous variables (heat duties and split fractions). The effectiveness of the approach is tested for small- and medium-size literature cases. The method demonstrates results comparable to or better than those reported in literature.