Entropy generation analysis of convective turbulent flow in alternating elliptical axis tubes with different angles between pitches; a numerical investigation

This paper presents a numerical analysis for studying entropy generation and the convective turbulent flow of an alternating elliptical axis (AEA) tube with different angles between the pitches at constant wall temperature boundary conditions. The turbulent flow of water fluid is simulated at Reynolds numbers of 10,000 to 60,000. The numerical results indicated that the multi-longitudinal vortices have a major influence on convective heat transfer, pressure drop and entropy generation. Two symmetrical vortices having the same direction of rotation close to the tube wall cause local wall shear stress and the local total entropy generation of the tube wall decrease. However, in some parts of the domain of the AEA tubes, these symmetrical vortices are absent. Therefore, there are different results for the local wall shear stress and the local total entropy generation in all domains of the AEA tubes. The Nusselt number and friction factor increases with an increase in Reynolds number and the angle between pitches of the AEA tube. The entropy generation analysis showed that the main source of irreversibility is by thermal entropy generation. The total entropy generation increases when there is an increase in the Reynolds number, as well as the angle between pitches of the AEA tube. Also, at Reynolds numbers of 20,000, the ratio of the total entropy generation of AEA tube to that of the circular tube is at its minimum.