Numerical study of heat transfer enhancement in the entrance region for low-pressure gaseous laminar pipe flows using Al₂O₃–air nanofluid

Abstract

The gaseous low-pressure nanofluid flow of a steady-state two-dimensional laminar forced convection heat transfer in the entrance region of pipes is numerically investigated. Such flows are of interest for many engineering applications like the nuclear reactor and electronic equipment cooling, heat exchangers, and many others. Physical parameters considered in this study are Reynolds number (Re), Prandtl number (Pr), nanosolid particles volume fraction (f), Knudsen number (Kn), and the aspect ratio (AR). These parameters ranges are as follows: 500 Re 2000, 0:76 Pr 0:95, 0 f 0:5, 0 Kn 0:1, and 1 AR 10. The outcome of this study shows that by increasing Kn, velocity slip and temperature jump at the solid boundaries increase. In addition, heat transfer is enhanced by dispersing Al 2 O 3 nanoparticles in the base low-pressure gaseous flow. Results show that there is no effect of the nanoparticles volume fraction with values below 0.03 on the average Nusselt number. The average Nusselt number increases (Nu) as the value of the nanoparticles volume fraction exceeds 0.03. For instance, at Re = 1000, results show that when dispersing Al 2 O 3 nanosolid particles with volume fractions of 0.3 and 0.5; there is an enhancement in the average Nusselt number of 30.35% and 136.74%, respectively, when compared to the case of dispersing Al 2 O 3 nanosolid particles of 0.03 volume fraction.. Moreover, it is concluded that the average Nusselt number (Nu) depends directly on Reynolds (Re), Prandtl (Pr) numbers, and the nanoparticles volume fraction (f) and inversely on Knudsen number (Kn) and the aspect ratio (AR) for the investigated range of parameters considered in this study. Finally, a correlation of Nusselt number among all the investigated parameters in this study is proposed as Nu = 0:976AR

A Brief Survey of Preparation and Heat Transfer Enhancement of Hybrid Nanofluids

“…In addition, the correlation for the total entropy generation among all the investigated parameters is proposed. Finally, Al-Kouz et al [80] conducted a numerical study to investigate heat transfer characteristics in the entrance region of laminar rarefied air/Al 2 O 3 flow in pipes. The effects of the aspect ratio, Knudsen number, Reynolds number and the nanosolid particle volume fraction on the heat transfer characteristics were presented, and a correlation of Nusselt number among all the investigated parameters is introduced.…”

Performance of a hybrid photovoltaic/thermal system utilizing water‐Al 2 O 3 nanofluid and fins

“…Moreover, they proposed a correlation of Nusselt number among all the parameters investigated in their study. In addition, Al‐Kouz et al investigated numerically the heat transfer enhancement in the entrance region for low‐pressure gaseous laminar pipe flows using air‐Al 2 O 3 nanofluid; they concluded that as Reynolds number, volume fraction of the nanosolid particles, and Prandtl number increase, then the average Nusselt number increases. In addition, they found out that as the aspect ratio and Knudsen number increase, then the average Nusselt number decreases.…”

Thermal Radiation and Mass Transfer Analysis in an Inclined Channel Flow of a Clear Viscous Fluid and H2O/EG-Based Nanofluids through a Porous Medium

“…Hisham et al [28] examined the flow of two-phase Maxwell fluids between parallel plates. Moreover, and due to the importance of nano/hybrid nanofluids in the enhancement of heat transfer, many researchers have investigated the impact of such fluids along with other physical parameters such as porous media, magnetohydrodynamics, rarefaction effects, and different geometries on the heat transfer [29][30][31][32][33][34][35][36][37][38][39][40][41]. The heat and mass transfer in three-layered channels was studied by Umavathi and Hemavathi [42].…”