Effect of nanofluid concentration on the performance of circular heat pipe

The goal of this paper is to experimentally study the behavior of nanofluid to improve the performance of a circular heat pipe. Pure water and Al_2O_3-water based nanofluid are used as working fluids. An experimental setup is designed and constructed to study the heat pipe performance under different operating conditions. The effect of filling ratio, volume fraction of nanoparticles in the base fluid, and heat input rate on the thermal resistance is investigated. Total thermal resistance of the heat pipe for pure water and Al_2O_3-water based nanofluid is also predicted. An experimental correlation is obtained to predict the influence of Prandtl number and dimensionless heat transfer rate, Kq on thermal resistance. Thermal resistance decreases with increasing Al_2O_3-water based nanofluid compared to that of pure water. The experimental data is compared to the available data from previous work. The agreement is found to be fairly good.