Improving the solidification performance of a shell-and-tube latent-heat thermal energy storage unit using a connected-Y-shaped fin

In this paper, the solidification process of the phase change material (PCM) in the shell-and-tube latent-heat thermal energy storage unit (LTESU) strengthened by fin is studied. For improving the strengthening effect of fins on the solidification performance of shell-and-tube LTESU, this paper proposes a novel connected-Y-shaped fin. The novel fin is inspired by the interconnection of the internal texture of the lotus leaf, and the branches of the two-level Y-shaped fins are connected into a whole by three metal annuluses. The numerical simulation method is applied to investigate the influence of the connected-Y-shaped fin on the solidification performance of PCM. The effects of annulus position and fin width on solidification performance are studied and analyzed. At the same time, the effects of the connected-Y-shaped fin on the solidification process under different wall temperatures and the radius ratio of outer to inner tube (gamma(i)) are investigated. The results indicated that the connected-Y-shaped fin can significantly enhance the discharging performance of LTESU. Compared with the traditional two-level Y-shaped fins, the optimized connected-Y-shaped fin can shorten the PCM solidification time by 53.9%. The optimum width ratio of the connected-Y-shaped fin should be 2. The optimum radius ratio of the outer annulus, middle annulus, and inner annulus to the outer tube should be 0.91, 0.64, and 0.41, respectively. The scope of application of the conclusion is that Ste = 0.139 - 0.496, and gamma(i) = 0.083 - 0.167. A novel connected-Y-shaped fin is proposed for the latent heat storage unit. The influences of fin structure parameters on the solidification process are discussed. Optimum fin parameters are recommended for maximizing the solidification rate. The novel fin can decrease the solidification time of PCM by 53.9%.