Numerical Study of Heat Transfer Enhancement for Low-Pressure Flows in a Square Cavity with Two Fins Attached to the Hot Wall Using Al2O3-Air Nanofluid

The gaseous low-pressure nanofluid flow of a steady-state two-dimensional laminar natural convection heat transfer in a square cavity of length L with two attached solid fins to the hot wall is numerically investigated. Such flows are found in many engineering applications, such as nuclear reactors and electronic cooling equipment. Physical parameter ranges in this study are as follows: 0 ≤ Kn ≤ 0.1, 103 ≤ Ra ≤106, 0 ≤ ϕ ≤ 0.2, LF/L takes the value of 0.5, HF takes the values of 0.25 to 0.75. Simulation results show that Nusselt number depends directly on the Rayleigh number and inversely on the Knudsen number. In addition, it is found that heat transfer will be enhanced by dispersing the nanoparticles of Al2O3 in the base low-pressure gaseous flow. Moreover, it is found that the Nusselt number of such flows increases as the nano-particle volume fraction increases for the investigated range of volume fractions considered in this study. In addition, a correlation of the Nusselt number among all the investigated parameters in this study is proposed as Nu = 0.2196 Ra0.0829 Kn–0.511 ϕ0.104.