Thermo ecological optimization of shell and tube heat exchangers using NSGA II

Shell and tube heat exchangers are the most important equipment in chemical processes plants. The heat exchanger design from the thermodynamic point of view is based on two fundamental aspects, the global heat transfer coefficient and the pressure drop. In 2007 a new thermodynamic property denominated "Entransy" was defined, which expresses the capacity of a body to transfer heat. This property can totally characterize the capacity to transfer heat of a shell and tube heat exchanger. The loss of this capacity is denominated "Entransy Dissipation". For evaluating the ecological impact of thermal machines, Angulo-Brown created in 1991 the "ecological function". In this paper the "entransy dissipation" and the ecological function were combined and a new expression for evaluating the ecological impact of shell and tube heat exchangers is proposed. A multi objective optimization of shell and tube heat exchangers considering irreversibility is also carried out. The ecological function and the cost were used as objective functions. For solving the of multi-objective optimization problem, the method of the Genetic Algorithms is used.