Synthesis of a multipass heat exchanger network based on life cycle energy saving

摘要

A method was described in this paper for the synthesis of a multipass heat exchanger network (HEN) based on minimization of the life cycle accumulative total cost. Considering the fouling resistance will be increased with the running of HEN, the overdesign was always optimized to minimize the total cost. A superstructure model was used in the proposed method to optimize multipass HEN. Fouling and heat transfer coefficients were used in different operating periods. Since the fouling resistance was increased slowly with running time, the life cycle running period was decomposed into several running intervals, and the corresponding heat transfer area was optimized for each heat exchanger. Then, the accumulative total cost was calculated and compared in different operating intervals to obtain the optimal design. Since the fouling resistance was varied with the running of HEN, the optimal HEN results were changed in correspondence to different accumulative total costs. Consequently, the optimal heat transfer area was obtained based on the minimization of the life cycle accumulative total cost. To show the reliability of this approach, it was applied to synthesize a HEN problem taken from open literature, and results were compared to those predicted from published methods. By comparisons of these results, the accumulative total cost for HEN based on life cycle energy saving is the most profitable one. The results demonstrated that it is necessary to consider the HEN optimization in different operating intervals and compare the corresponding accumulative total cost in order to realize the life cycle energy saving. (C) 2016 Published by Elsevier Ltd.