Numerical Appraisal of Heat Transfer and Flow in Concentric Annuli Permeable and Impermeable Fins by using Nanofluids

Numerical study was carried out to investigate the natural convection heat transfer enhancement by using utilizing various nanofluids in a three ? dimensional annulus. The annulus between two concentric cylinders with porous (permeable)fins , solid (impermeable) fins, without fins and these fins attached to the inner cylinder. The inner cylinder and two fins are maintained at constant wall temperature (CWT),while the outer cylinder is diathermal (adiabatic).The problem was solved numerically using Alternating Direction Implicit (ADI) method. The two types of nanoparticles used in his article metallic silver copper (Cu) and nonmetallic zirconium oxide (ZrO2). The numerical results for three cases considered are given in terms of stream function contours and isotherms for values of Rayleigh number Ra of 103,104and105 and volume fractions Φ of 1%, 2% and 5%. As well as this article indicating to the effect fin inclination angles and annulus inclination angles. The numerical results show that As the solid volume fraction increases, the heat transfer is enhanced for all values of the Rayleigh number and volume fraction. Nanoparticles concentration did not reveal serious effect on the secondary flow and the average skin friction coefficient while increasing volume fraction and Rayleigh number significantly increase Nusselt number. The values of the average Nusselt number by using nanofluids are compared with distilled water for three cases porous fins , solid (impermeable) fins, without fins. Results showed that the annulus porous fins provided higher heat transfer rate than annulus solid (impermeable) fins and annulus without fins. The enhancement in heat transfer of nanofluids for annulus with porous fins, solid (impermeable) fins and annulus without fins at (5 %) volume concentration of (Cu) nanoparticles increases (82.25 %, 70.15 %,50.33 % ),while of (ZrO2) (69.35 %, 52.44 %,37.42 % ) respectively compared with the base fluid (distilled water).