CFD analysis of heat transfer and pressure drop in helically coiled heat exchangers using Al2O3 / water nanofluid

In this investigation, the heat transfer coefficient and pressure drop of a helically coiled tube heat exchanger handling Al2O3/ water nanofluids is made by using computational fluid dynamics fluent (CFD) software package. This was done under laminar flow condition in the Dean number (De) range of 1650–2650 and the nanoparticles volume concentration of 0.1%, 0.4% and 0.8%. The effect of some important parameters such as nanoparticle volume concentration and Dean number (De) on heat transfer and pressure drop is studied. The coiled tube side Nusselt number (Nu) is found to be 30% higher than water at maximum De. The maximum pressure drop is found to be 9% higher than water. It is also found that the Nu and pressure drop significantly increase with increasing particle volume concentration and De. It is also found that the experimental friction factor increases with increasing the particle volume concentration and De. The CFD Nu and pressure drop results have been compared with the experimental and theoretical results. On comparison, it is found that the CFD simulation results show good agreement with the experimental and theoretical results. It is concluded that the CFD approach gives good prediction for heat transfer coefficient and pressure drop in a shell and helically coiled tube heat exchanger using Al2O3/ water nanofluids. The average relative error between experimental Nu, pressure drop results and CFD results are found to be 8.5% and 9.5% respectively.