Numerical solution for optimization of curved turbulator geometry in a double-pipe heat exchanger containing two-phase Cu-GO/Therminol VP-1 hybrid nanofluid to achieve maximum exergy efficiency

Abstract

In industry, heat exchangers (HE) either remove excess heat from a device to cool it or keep a reaction warm within a certain temperature range. Most of the HEs used in oil, gas, and petrochemical industries are double-pipe types. The present study was carried out in steady state and utilizing the pressure-based finite volume method (FVM). The Two-phase Cu-GO/Therminol VP-1 (copper-graphene oxide) hybrid nanofluid (HN) is modeled utilizing the mixture model. The turbulence model is the k-ε model. The range of changes of Re and φ of GO and Cu nanoparticles is 17000 to 41000 and 0 to 3%, respectively. Also, the study is done for different geometric shapes of the novel turbulator with the curvature angles of β = 0⁰, 45⁰, 90⁰, and 135⁰. The numerical results demonstrate that an increment in Re, i.e. an increase in the HN velocity, enhances the Nusselt number (Nu) and convective heat transfer coefficient (HTC). The maximum amount of thermal performance in the double-pipe exchanger is related to the use of the turbulator with β = 135⁰ and φ = 3%. In addition, for all cases, the values of the performance evaluation criteria (PEC) is greater than 1. Therefore, it is appropriate to use the innovative turbulator (IT) and change its curvature angle in the HE in terms of PEC. For all values of β, the exergy efficiency is improved with φ and Re and is reduced with β.