University of TehranEnergy Equipment and Systems2383-11113220151201Numerical simulation of Al2O3–water nanofluid mixed convection in an inclined annulus971111702910.22059/ees.2015.17029ENHadiImaniFaculty of Mechanical Engineering, Tarbiat Modares University, Iran
P.O. Box 14115-143 Tehran, IranAliCheraqiFaculty of Aerospace Engineering, KNTU, P .O. Box 16765-3381 Tehran, IranAliJafarianFaculty of Mechanical Engineering, Tarbiat Modares University, Iran
P.O. Box 14115-143 Tehran, IranMohammad MahdiHeyhatFaculty of Mechanical Engineering, Tarbiat Modares University, Iran
P.O. Box 14115-143 Tehran, IranJournal Article20150718<em>Laminar mixed convection of Aluminium oxide (Al<sub>2</sub>O<sub>3</sub>)–water nanofluid flow in an inclined annulus using a single-phase approach was numerically studied. Constant heat flux boundary conditions were applied on the inner and outer walls. All the thermophysical properties of nanofluid, such as, viscosity, heat capacity, thermal conductivity, and thermal expansion coefficient, except density in the body force term were assumed to be constant. Based on Boussinesq’s hypothesis, density was assumed to be a linear function of temperature. The nanofluid properties were calculated in terms of constant properties of nanoparticles and the base fluid. Using the finite volume method the continuity, momentum, and energy equations were numerically solved. Numerical simulations were conducted for the nanoparticle concentrations of 0, 2, and 5% and five different inclination angles including-30<sup>o</sup>,-15<sup>o</sup> ,0 , +15<sup>o</sup>, and+30<sup>o</sup>. Results showed that a variation in the inclination angle affected the Nusselt number on the inner wall more than the outer one. The Nusselt number in negative angles was higher than in the positive ones, so that at a volume fraction of 5%, the average Nusselt number at the inner wall decreased almost 2% when changing the angle from -30<sup>o</sup> to+30<sup>o</sup>. The local Friction factor in the positive angles was higher than in the negative ones.</em>http://www.energyequipsys.com/article_17029_79124ceec89e23d1d110f62978525868.pdf