Abstract
This research presents a numerical analysis of the three-dimensional simulation of heat transfer and fluid flow incloded forced convection through a square-section channel with different ribs and the effect of addition of nanoparticles with constant heat flux up and down the channel. The single-phase approach of Nano-fluid is employed; it is assumed that the base fluid (water) and nanoparticles (Al2O3) are treated as a homogeneous mixture. The study assumes that the Nano-fluid incompressible, steady and laminar. The nanoparticles used in 25 nanometers and with volumetric concentration (1-5) %. ANSYS 18.1 FLUENT is a computational fluid dynamics (CFD) program. The finite volume method was used to solve the ruling equations. To ensure accuracy of the results, the validity was performed with previous studies of the channel and under the same boundary conditions and the result was Compatible. By using ribs at the top and bottom of the channel in two alignment inline and staggered, and five ribs per surface, and in tow shapes (triangle A and triangle B). The aspect ratio is equal to (2(. with five different values for Reynolds numbers (300, 500, 700, 900 and 1200). The results showed that triangular ribs type (A) with staggered alignment represent the optimal state of the all studied shapes and at all Reynolds numbers. The maximum value of the performance evaluation criteria (PEC) was 1.8561 and the use of Nano-fluid at a concentration of 5% compared to 1.5991 for the same channel using water only, and at Reynolds number 1200. At 5% volume concentration, the heat transfer coefficient (h) was 29.78% higher than the thermal conductivity increase of 16.48% when using only the Nano-fluid. When adding the triangular ribs type (A), the increase in heat transfer coefficient (h) is equal to (143.03%). Actually, other factors such as dispersion, Brownian motion, hermophoresis, vortex generator, and nanoparticles migration also are responsible for the enhancement of convective heat transfer.
