Numerical study on forced convection heat transfer of TiO2/water nanofluid flow inside a double-pipe heat exchanger with spindle-shaped turbulators

Heat exchangers have a substantial role in industrial processes. Efficient designs must be introduced to balance heat exchanger effectiveness and pressure drop in order to attain the anticipated tradeoff between the system's size and efficiency. Herein, a numerical study has been implemented on the impact of using nanofluid inside a double-pipe heat exchanger equipped with spindle-shaped turbulators on the heat transfer rate and pressure drop in a turbulent flow regime. The two-phase mixture method has been employed and the characteristic equations, namely, continuity, momentum, energy, turbulent kinetic energy, turbulent losses, and the particle volume fraction equation have been solved for studying the flow. The numerical finite volume method has been utilized to discretize and solve the equations. The results show that by adding 0.01 volumetric fraction of nanoparticles to the base fluid, the transfer heat transfer coefficient increases by 11.45% at Re 4000, and 11.91% at Re 7000, in comparison with the base fluid. Also, although increasing the volume fraction of nanoparticles reduces the heat exchanger performance index, however, this reduction is slight when associated with the base fluid rate in the volume fraction of 0.01.