A simultaneous optimization approach for heat exchanger network (HEN) synthesis and detailed shell-and-tube heat exchanger (HE) design including phase changes is proposed based on a genetic/simulated annealing algorithm (GA/SA). Firstly, a model for HEN synthesis considering utility HEs with phase change is established by combining the improved stage-wise superstructure model of HEN synthesis with non-isothermal mixing of splits and detailed design models of HEs involving phase change, the minimum total annual cost accounting for pumping cost is set as the key objective. Secondly, two alternative connection schemes for HEs, which are referred to as one-stream series-wound and one-stream parallel in the stage-wise superstructure of the HEN, were applied. Thirdly, a simultaneous optimization strategy is proposed. Required areas of HEs obtained by stage-wise superstructure, overall heat-transfer coefficients and pressure drops based on the dimension parameters of HEs are used to connect HEN synthesis and the detailed design of each HE. Finally, a flowchart of optimization procedures using GA/SA was presented to solve the problem, and an inner iterative loop of the area of HE is used to guarantee the feasibility of the solution. Two examples results are used to illustrate the availability of the proposed model and algorithm. (C) 2019 Elsevier Ltd. All rights reserved.