a novel method (a tube with successive increase and reduction in diameter) to increase nanofluid heat transfer in a tube

In this paper, a new geometry has been proposed to increase heat transfer in tubes. the fluid used was water-aluminum oxide (al2o3) nanofluid. the results showed that the proposed geometry in this study (compared to a simple tube) in addition to increasing heat transfer, reduced the flow pressure drop, which is a great advantage over previous methods. reynolds numbers of 2-300 and nanoparticle volume fraction of 0-3.5% have been investigated. profile of temperature, velocity and pressure has been presented for different reynolds numbers, nanofluid volume fractions and sections of geometry. in addition, variations of nusselt number in different reynolds numbers and volume fractions have been studied. for the reynolds number 50, increasing the temperature of the fluid of the geometry proposed in this study was 52% higher than that of a simple tube under the same operating conditions. for the reynolds number 50, the pressure drop of the geometry proposed in this study was 24% less than that of a simple tube under the same operating conditions. the results showed that the change in volume fraction of nanoparticles had a small effect on the nusselt number. it was found that increasing the reynolds number increased the nusselt number.