Hydrodynamic-thermal variations of a nanofluid in a tube equipped with a twisted tape: The study of the structural effects of the twisted tape

Thermal energy is one of the most important issues in most industries, because conversion of energy from fossil fuels to thermal energy occurs in almost all conventional industries. Therefore, considering the lack of fossil resources and the increasing pollution of human environments, attention to the proper use of thermal energy should be considered by researchers. In recent years, attention has been focused on the use of new technologies to increase the efficiency of thermal systems, including heat exchangers. Among these technologies, which are considered in this paper, is the simultaneous use of nanofluids and torsion strips placed inside the heat exchanger tube. In the present numerical study, for the first time, a two-phase Euler-Lagrangian numerical simulation has been used in this geometry to overcome the shortcomings of previous monophasic studies. The effects of independent variables such as the volume fraction of nanoparticles and Reynolds number and the structural variables of the torsion bar, such as the shear and the torque ratio on heat transfer and the coefficient of friction, have been investigated. The results showed that other variables except Reynolds have the same qualitative effects on heat transfer and friction coefficient.