Effectiveness improvement and optimization of shell-and-tube heat exchanger with entransy method

Abstract

In this study, the optimum design of shell and tube heat exchangers is investigated by applying the entransy dissipation theory and genetic algorithm method. In fact, this article presents solutions to increase performance of heat exchanger with changes in geometry, such as the number of tubes, tube diameter, and baffle geometries. According to the second law of thermodynamics, the most irreversibilities of convective heat transfer processes are due to fluid friction and heat transfer via finite temperature difference. Entransy dissipations are due to the irreversibilities of convective heat transfer. Therefore, the minimization of them has been chosen as objective function, and the corresponding problem optimized under the conditions of the constant heat transfer rate and constant thermal surface. The results show that the single-objective optimization at constant heat transfer rate, can be improve the performance of heat exchanger significantly and in constant heat transfer area increases the effectiveness, but it leads to increase of pump power consumption. It is found that, the fluid friction impact is not fully considered when the working fluid of heat exchanger is liquid in single-objective optimization approach. In order to solving this problem, a multi-objective optimization approach to heat exchanger design is established.