عنوان مقاله [English]
Use of thermal energy storage using latent heat fusion of phase change materials is an effective and efficient way for energy storage in solar water heaters. The present paper is an experimental study carried out at last week of August 2014, in Jundi-Shapur Industrial University of Dezful City. First, in this study, two eccentric double tube heat exchangers with different eccentricities were built and each was separately placed in the circuit of a forced solar water heater including a flat plate solar collector, a storage tank, and a hot water circulating pump. Through the internal tube of heat exchanger passes the water heated by the solar collector, while the shell contains paraffin wax as the phase change material to which copper oxide nanoparticles are added to increase thermal conductivity. This study experimentally investigates the effect of copper oxide nanoparticles and also the effect of eccentricity on the charge of paraffin wax as the phase change material and energy storage due to the change in both of these parameters. Experimental results indicate that paraffin wax containing 3%, 1% and without nanoparticles, have reached their melting points at 14:20, 15:20 and 16:20, respectively, in the heat exchanger with 1 inch eccentricity , Paraffin wax with 3% nanoparticles has reached its melting point at 14:20 and 15:40 in the heat exchangers with 1-inch eccentricity and 0.5-inch eccentricity, respectively. . It is worth noting that lowering the heat exchanger internal tube and adding nanoparticles significantly improve the fusion (charge) of paraffin wax and also thermal energy storage.