Numerical investigation of thermohydraulics performance in elliptical twisted duct heat exchanger

Abstract

Heat transfer behaviour in twisted elliptical duct swirl generator is investigated numerically. Twisted geometry is a widely used technique for heat transfer enhancement. This work presents the investigation of a elliptical twisted duct (ETD) for turbulent heat transfer in air using computational fluid dynamics (CFD) modelling. In the present paper, transition—SST model which can predict the change of flow regime from laminar through intermittent to turbulent has been used for numerical simulations. While the aspect ratio of major and minor axes of the elliptical duct is 0.5, the pitch length (Y) is varied between 0.5 and 1.0. The results indicate that the smaller pitch length yields a higher heat transfer value with relatively lower performance penalty. The transition from laminar to turbulent regime is observed between Reynolds numbers of 1000–3500 for all cases. For all investigated cases, heat transfer enhancement (η) tends to increase with the increase of Reynolds number. This result is useful for the design of solar thermal heaters and heat exchangers.