Performance analysis of turbulent convection heat transfer of Al2O3 water-nanofluid in circular tubes at constant wall temperature

The present paper analyzes the turbulent convection of Al2O3-water nanofluid inside a circular section tube subjected to constant wall temperature. The analysis is developed numerically, by using the mixture model which has been proved to be a convenient method to simulate nanofluids behavior. The numerical model is successfully validated by means of analytical equations and experimental correlations. The study is focused on the analysis of the entropy generation along the tube axis, showing an opposite behavior of the frictional entropy generation and thermal entropy generation, thus establishing a minimum point of total entropy generation along the tube length. Despite of the increase of the average heat transfer coefficient, the average total entropy generation increases at the increase of Re and of the concentration of nanoparticles. The results reported in the present paper are believed to be useful for the thermal optimization of nanofluids flow inside tubes.