Document Type : Research Paper
Assistant Professor, Faculty of Modern Sciences & Technologies, University of Tehran, I.R.Iran
Graduate Student, Department of Mechanical Engineering, University of Zanjan, I.R.Iran
In this paper, the effects of adding nanoparticles including Tio2 to a fluid media for purpose of free convection heat transfer improvement were analyzed. The free convection was assumed to be in laminar flow regime and the solutions and calculations were all done by the integral method. Water, as a Newtonian fluid, was considered the base fluid (water) and all the thermo physical properties of the nano-fluids have been considered unvarying. According to the calculations performed and all depicted graphs, one can thoroughly consider that adding nanoparticles to the fluid generally causes increment and development of heat transfer coefficient. Increasing nanoparticles concentration increases the heat transfer rate. The heat transfer increment is also dependent on the nanoparticles thermal onductivity and the viscosity theory used. In this study, four different kinds of theories were used for the nano-fluids viscosity calculations. The effects of viscosity on the nano-fluids thermal conductivity can be obviously seen. All the calculations have been done for the concentrations lower than 4%.