Investigating the thermal energy storage inside a double-wall tank utilizing phase-change materials (PCMs)

In present study, the efficient parameters on thermal energy storage in a double-wall tank with phase-change materials have been investigated. At first, the effect of using fins in distribution of phase-change materials has been studied. Inside the tank where the inlet-heated water is there, the inlet temperature and Reynolds number have been investigated. Also, on tank walls where the phase-change materials are placed, the effect of using of fins and the type of phase-change materials has been investigated. By mounting fins on areas with phase-change materials, the melting time reduces significantly. Therefore, after mounting fins, the melting of phase-change materials has been reduced from 60 to 80% in approximately 8 h. In water zone, by increasing inlet temperature from 340 to 360 K, the melting time of phase-change material reduces significantly, in a way that, after approximately 8 h, the amount of melted materials changed from 67 to 87%; however, the change in Reynolds number does not have any considerable influence. In final section, the effect of thermophysical properties of phase-change materials on melting process has been studied. The obtained results reveal that using materials with lower specific heat and melting temperature causes the reduction of melting time, and hence, for melting 90% of phase-change materials with wax, 14 h is needed, while, by using SavEHS34, these materials change their phase in 5.5 h.