Heat exchanger network design with multi stream exchangers using stage wise superstructure
Abstract Nowadays, most of heat exchanger network (HEN) publications are focused on conventional two stream heat exchangers in HEN. Multi stream heat exchangers (MHEX) referred as another type of exchanger which provides many advantages over conventional two stream heat exchanger such as substantial saving on both capital cost and volume. Conceptually, MHEX could replace whole HEN. In this work, the overall methodology of multi stream plate fin heat exchanger type is divided into three design phases. For the first phase, the HEN synthesis by stage wise superstructure done by Yee et al. (1990) is used to minimize overall hot and cold utilities. In the second phase, the composite curves are generated based on enthalpy intervals from pinch analysis which subdivide the MHEX into block sections and help specify the stream population in each section. In the last phase, the conceptual design model of multi stream plate fin heat exchanger is proposed with calculation of pressure drop and exchanger volume in each section. The continuous variables of basic fin geometries for all fin types based on the work published by different researchers and thermal hydraulic model are optimized simultaneously by minimizing the MHEX volume in each section.