Numerical Simulation of the Performance of Applying Different Nanofluids in a Tube with a 90° Bend at the Center of the Tube

This research manuscript addresses the study of the performance of a flat tube having a 90° bend under the flow of three different nanofluids such as copper oxide, multiwalled carbon nanotubes, and aluminum oxide/water nanofluids at different inlet fluid temperatures and Reynolds numbers. The performance of the flat tube is analyzed under the Reynolds number between 5000 and 11000 and a fluid inlet temperature range of 35°C–50°C. The results obtained in this study show that the heat transfer coefficient increases with the increase in volume concentration as well as Reynolds number. The maximum heat transfer coefficient is obtained using multiwalled carbon nanotubes followed by copper oxide and then aluminum oxide. This study also illustrates that the friction factor increases with the increase in volume concentration and decrease in Reynolds number. The results of the numerical study have been validated with the help of an experimental study. The study has proved that the use of nanofluids instead of the conventional fluid can lead to reducing the size of the tube for the same amount of heat transfer which can prove the reduction of the size in heat transfer equipment. Furthermore, it is also observed in this study that the presence of the 90° bend in the flat tube improved the heat transfer performance due to the increased turbulence at the bent section of the tube.