Effects of nano-fluids types, volume fraction of nano-particles, and aspect ratios on natural convection heat transfer in right- angle triangular enclosure

Abstract EN

This study investigates natural convection heat transfer and fluid flow characteristic of water based nano-fluids in a right-angle triangular enclosure, where the left vertical wall is insulated, the right inclined wall is cooled, and the horizontal wall is heated by spatially varying temperature.

Governing equations are solved using streamvorticity formulation in curvilinear coordinates.

Streamlines, isotherms, local and average Nusselt number, moreover to NUR factor are used to present the corresponding flow and thermal fields inside the triangular enclosure.

Calculation were performed for three aspect ratio of enclosure geometry (AR = 0.5, 1, 2), solid volume fractions of nanoparticles ranging from PHI = 0, to 4 %, and Rayleigh number varying from 104 to 106.

Three types of nano-particles are taken into consideration : Cu, Al 2O3, and TiO2.

The results show that, the average heat transfer rate increases significantly as particle volume fraction and Rayleigh number increase.

Also, the type of nano-fluid is a key factor for heat transfer enhancement where the high values are obtained when using Cu, TiO2, and Al2O3 nano-particles respectively.

Finally, it is observed that the aspect ratio of the enclosure is one of the most important on flow and heat transfer.

Increasing the AR leads that to increase the flow strength and heat transfer rate.