A general model is proposed for optimal operation of heat exchanger network(HEN)

aiming to achieve two goals: 1) all controlled temperatures are kept at their targets; 2) operating cost is minimized. The model is formulated as non-linear program(NLP)

which consists of exchanger model

splitter model

mixer model

by-pass model and relation model between unit models. The HEN structure is represented with stage-wise superstructure presented by Yee and Grossmann(1990)

which is developed for considering non-constant film coefficient. A solution strategy based on particle swarm optimization algorithm is developed for NLP problem

which promises simple

fast and robust searching procedure. The proposed method is applied to four benchmark problems reported by published literatures

and the optimal results prove that the method is more effective to optimal operation problem of HEN.