SYNTHESIS OF HEAT-EXCHANGER NETWORKS CONSIDERING LOCATION OF PROCESS STREAM SOURCES

The synthesis of a heat exchanger network (HEN) is an active field of interest in process engineering in order to develop a systematic proce dure for finding an optimal network and individual heat transfer areas to meet the target temperatures at minimum total cost, which consists of energy and capital costs. Previous methods have given priority to identifying the minimum energy cost at a given minimum approach temper ature (Delta T-min) common to all heat matches between the heat source s and sinks beforehand. However, Delta T-min for each match depends on the physical properties, the temperature levels and the locations of the process stream sources, which are strongly related to the total co st effect. The purpose of this study is to develop a HEN synthesis met hod considering the energy and capital costs simultaneously, and an ev olutionary approach is found to be suitable for the nature of this pro blem. In adopting this approach, generating an initial network and sea rching for the neighboring ones becomes important, In this study, an a lgorithm of selection criterion is developed to generate an initial ne twork based on the thermodynamic and economic consideration. Moreover, three evolutionary rules: changing the neighboring heat match; adding heat match; and varying heat transfer area have been proposed. These rules enable evolutionary searching without missing a better network. Finally, the effect of the developed evolutionary method is demonstrat ed through an illustrative example problem.