ali saadi

An experimental study was carried out in order to find out the effects of ZnO Nano fluid with a mean diameter of 30nm on heat transfer, pressure drop and termal performance of a double tube heat exchanger, where the volume fraction of nanoparticles in the base fluid is less than 1% (low concentration). Ethylene glycol and Nano fluid with particle volume fraction of 0.5%, 0.7% and 1% are used as working fluid. The experiments are carried out in the fully developed turbulent regime. The results indicate that addition of low value of nanoparticles to the base fluid motivates the heat transfer to increase remarkably. The Nano fluid also show that the pressure drop of Nano fluid is slightly higher than that of the base fluid and does not increase with increasing the nanoparticles volume fraction. In this paper, experimental results have been compared with the existing correlations for Nano fluid convective heat transfer coefficient in turbulent regime. Also Nusselt number and friction factor were considered in definition of thermal performance factor for all cases are greater than unity which indicate that this Nano fluid enhances the heat transfer without huge penalty in pumping power. Thermal performance factor maximum is obtained 1.32% by 1% volume fraction and between 1.03%~1.20% by 0.5% volume fraction. Also, for Reynolds about 6300, nusselt number have increased by 0.7% volume fraction, about 19.8 percent. Hence, applying the methods studied here could be considered as a good choice in particle application.