Comparative investigation of nanofluid heat transfer in vertical annular channel with cosine heat flux by experimental and numerical methods

One method to improve heat convection is to increase the heat transfer coefficient of the working fluid. Adding metal or non-metal nanoparticles into the base fluid, known as nanofluid, is a technique to enhance the heat transfer coefficient. Research in the field of nanofluids has grown significantly in the last two decades. In this study, the effects of a homogenous combination of Al2O3 and TiO2 nanoparticles with deionized water are investigated. The thermohydraulic performance of the nanofluid inside the vertical channel is analyzed by experimental and numerical methods for turbulent and laminar flow. The turbulence model utilized in computational fluid dynamics is the k-ε model. The heating rod in the test section produces 1 kW cosine heat flux. The results show that increasing the concentration of nanoparticles significantly reduces the maximum temperature of the rod. The use of 1% homogeneous nanofluid reduces the maximum temperature by 20% at the Reynolds of 950 and 9.5% at the Reynolds of 4200 compared to pure water. Also, the heat transfer coefficient increases with the addition of nanoparticles. The difference between the results obtained by the k-ε turbulence model and the experimental method shows a difference of 10% to 13%. This research shows that the combined nanofluid with suitable thermal performance can be one of the working fluids in future thermal cycles.