LAUSR

Abstract The present research aims to study the charge and discharge processes within a triplex-tube system. In this system, the water flows inside the outer and inner pipes and the annulus region is filled with RT82 as the phase change material (PCM). The aim of this investigation is to evaluate the effects of adding Al2O3 nanoparticles with concentration of 0 and 0.05 as well as influence of geometry, fin installation, and other influential factors on these processes. The simulations were performed using ANSYS Fluent 18.1 and verification with previous articles guaranteed the correctness of modeling. The flow was considered laminar and the Boussinesq approximation has been employed to the problem. Moreover, the stored energy was evaluated. The results suggest that the usage of nanoparticles leads to significant conduction enhancements and can reduce the solidification and melting time in system about 12 and 6.4%, respectively. Also, the fin installation results in decrement of solidification and melting time by 5 and 37.8%, respectively.