Numerical simulation on heat transfer of nanofluid in conical spiral heat exchanger

In this research article, the performance of a conical spiral heat exchanger with rectangular cross sections is numerically investigated by using two different nanofluids, aluminium oxide/water (Al2O3/water) and copper oxide/water (CuO/water) nanofluid. For this purpose, the effects of nanofluid concentration on the secondary flow, pressure drop, heat transfer and figure of merit (FOM) (the ratio of total heat transfer to the required fluid for pumping) are investigated. On the structured grid, the continuity, momentum, and energy equations are solved by employing a finite volume method. Results indicate that by enhancing the concentration of a nanofluid, the formed secondary flow gains more power. Based on the obtained results, the pressure drop increases with enhancing the nanofluid concentration along the tube. The heat transfer rate is slightly increased by adding nanoparticles to the base water fluid in very low concentrations, but with increasing the concentration of nanofluids, the heat transfer rate reduces. Moreover, FOM decreases with increasing nanofluid concentration. This variation is higher for copper oxide compared to alumina nanofluids at lower concentrations, while it is higher for alumina nanofluid at higher concentrations.