Improvement of Energy, Exergy Efficiency and PEC Index in a Heat Exchanger Equipped With Turbulators Under The Effect of a Magnetic Field

چکیده مقاله

A double-tube heat exchanger equipped with vortex generators is simulated under the effect of a magnetic field. The internal tube of this heat exchanger is equipped with blade-type vortex generators, having various shapes. A magnetic field is employed to enhance thermal efficiency in the double-tube heat exchanger, with Hartmann numbers ranging from 35 to 155. The applied hybrid nanofluid is composed of Syltherm 800, iron oxide, and graphene oxide at volume fractions (φ)of 0, 1.75, and 3.75%. The study is conducted under steady-state conditions using a two-phase model with Reynolds numbers (Re) ranging from 25,000 to 55,000, utilizing the k-epsilon turbulence model. The results display that as the Re increases, the convective heat transfer coefficient rises. The maximum increase in the Nusselt number (Nu) is observed in the heat exchanger equipped with vortex generators of Sample 3, while the minimum occurs when the heat exchanger is bare. Additionally, as the Hartmann number increases from 35 to 155, the exergy efficiency also rises. Exergy efficiency increases with Reynolds numbers up to 35,000 and then decreases. It is found that the use of a magnetic field maximizes exergy efficiency at a Re of 35,000 and Hartmann number (Ha) of 155 for the heat exchanger equipped with Sample 3 vortex generators.