Functionalized Multi‐Walled carbon Nano Tubes nanoparticles dispersed in water through an Magneto Hydro Dynamic nonsmooth duct equipped with sinusoidal‐wavy wall: Diminishing vortex intensity via nonlinear Navier–Stokes equations
Quyen Nguyen, Dariush Bahrami, Rasool Kalbasi, Arash Karimipour
Abstract
In this study, the efficacy of applying a magnetic field on a double‐pipe heat exchanger equipped with a sinusoidal‐wavy wall on the effectiveness and entropy generation was investigated. Making sinusoidal‐wavy wall has a positive effect as well as a negative effect. Using sinusoidal‐wall increases the heat transfer area (positive effect), and on the other hand, it creates vortex (negative effect). The rate of improvement in heat transfer is dependent on the competition between positive and negative effects. Owing to using the sinusoidal‐wavy wall, the heat transfer enhancement was 1.56%. Applying the magnetic field, the vortex intensity diminished (negative effect reduction). In the presence of the magnetic field, heat transfer enhancement intensified from 1.56% to 19%. It was found that the presence of the magnetic field increases the entropy generation (due to the rise in temperature gradient) and, on the other hand, reduces the entropy generation (due to the diminishes in the vortex strength). In the presence of sinusoidal‐wavy wall, the increase in Hartman number led to decrease in total entropy generation. Due to the presence of the sinusoidal‐wavy wall in the double pipe heat exchanger (Hartman number = 0), the entropy generation was increased up to 18%. Applying the magnetic field diminished, the irreversibility correspond to sinusoidal‐wavy wall. At Ha = 60, owing to using the sinusoidal‐wavy wall, total entropy generation increased by only 8%.