Numerical optimization of heat exchangers with circular and non-circular shapes

Abstract

A circular tube bundle is one of the simplest geometries that is widely used for heat transfer applications. However, in the recent years, cross-flow heat exchangers with non-circular tube arrangement have been receiving increased attention. The main purpose of this work is to gain insight into the characteristics of heat transfer and fluid flow in different tube bundles arrangements: circular, ellipsoidal and wing-shaped, for heat exchangers taking into account local and bulk entropy generation. All tube shapes are investigated under similar operating condition. This could provide a new way for engineers to design an optimal network of heat exchangers allowing the enhancement of heat transfer and recovery in industrial applications. We conduct a two-dimensional numerical CFD model using finite volume discretization to evaluate the performance of these systems. The effects of pressure drop, exergy and enthalpy balances are both investigated. Entropy generation is sought in order to find the best tube bundles arrangement. Heat transfer correlations are obtained for different situations of tube shapes and suggestions are made for the best geometry that minimizes the total entropy generation (i.e. the irrevesibilities).

Keywords

• Heat exchanger
• Tube bundles
• Circular tube
• Non-circular tube
• Optimization
• Simulation
• Pressure drop
• exergy
• Entropy generation