Unsteady heat transfer modeling for a solar thermal storage unit incorporating nanoparticles

In the present article, spider's web shaped enclosure has been introduced as a container for thermal storage and paraffin has been utilized for saving energy. The unsteady melting process has been simulated based on FVM in which gravity force effect has been involved and a two dimensional domain has been considered. According to different thickness of layers and type of materials, 27 cases have been generated which were simulated by means of ANSYS FLUENT. The applied paraffin has a melting temperature of 82 ?C and alumina nanoparticles with concentration of 0.04 have been loaded into PCM to accelerate the process. Stream function, isotherms and LF have been reported in each space of domain as contours in three levels of time. Decreasing the range of t2 and t1 for all cases causes melting time to decrease around 21.37 % and 12.38 %, respectively. The minimum needed time happens when t1 = t2 = 0.25 for Al structure in which 984 s need to obtain full melting