Heat transfer and flow optimization of a novel sinusoidal minitube filled with non-Newtonian SiC/EG-water nanofluids

In present study heat transfer and forced convection flow of non-Newtonian two-phase ethylene-glycol/water mixture based nanofluid through a wavy-sinusoidal minitube has been investigated. The 2D governing system of equations is solved numerically in the computational field using the Control-Volume-Approach founded on the SIMPLE technique. Flow velocities or Reynolds numbers are varied in the turbulent regime range from Re=6000 to Re=15,000 and the tube walls boundary condition is uniform temperature. The optimization was conducted considering five different constant and variable a(x) amplitudes, five various constant and variable 2(x) wavelengths and five various phase shifts in order to achieve the most advantageous geometry in view of the highest thermal-hydraulic performance evaluation criterion index. From obtained results in present paper, it has been realized that the wavy-wall minitube thermal-hydraulic performance is seriously affected with varying the wavy amplitude, wavelength and phase shift. The highest thermal-hydraulic PEC has been obtained for the amplitude of alpha=0.5 mm with increasing wavelength and phase shift of theta=90 degrees at Re=6000 Reynolds number. After opting of the optimum geometry, Silicon-Carbide (SiC) nanoparticles were added to base fluid in volume fraction of 4% and sizes of 16 to 90nm. Based on results, the PEC of EG/water based nanofluid with nanoparticle diameter of d(np)=90 nm has been conducted to be the most efficient among all models during investigated range of flow velocities. PEC amount for optimum tube using EG/water based SiC nanofluid with volume fraction of phi=4% and nanoparticle diameter of d(np)=90 nm at Re=15,000 is about 1.670.