Multi-objective Optimization of Shell-and-Tube Heat Exchangers According to Different Expressions of the Second Law of Thermodynamics

Shell-and-tube type heat exchangers (STHE) are the most important part of non-combustion heat transfer equipment in industrial processes. The literature provides extensive information on various methods of optimizing the design of STHE, however, as a rule, it is carried out only with the aim of minimizing costs as an objective function. In this paper, it is proposed to use multi-purpose optimization of STHE using new thermodynamic and environmental expressions as objective functions. Its implementation is possible with the use of genetic algorithms of the second generation. The paper presents a procedure and a mathematical model for multi-purpose optimization, in which five objective functions are proposed to be used: the coefficient of thermal resistance, thermal efficiency, environmental function, total cost, including operating costs, and the total amount of dissipated entransy. The concept of entransy is proposed for the first time to create a new ecological function used as a criterion for optimizing STHE. The novelty of the proposed work lies in the fact that it optimizes simultaneously taking into account mechanical and vibration limitations, the design of the heat exchanger, as well as taking into account the parameters of thermohydraulic processes occurring in it. The approbation of the methodology was carried out on the basis of a specific case study, which had previously been repeatedly used by various authors to verify the results obtained. The multi-purpose optimization of the STHE made it possible to develop design options with minimal costs at a given thermal load and with geometric options that are adaptable to the space available for installation and the availability of auxiliary systems.