Optimal design and performance investigation of latent heat thermal energy storage system integrated with nonuniformed topology fins

The intrinsic low thermal conductivity of PCM restricts performance of phase change systems. Incorporation of metal fins represents an efficacious strategy to remediate the inferior thermal performance. In order to establish more efficient heat transfer, a nonuniform topology-based fin structure fitting for a rounded rectangle shell-tube phase change unit is designed in this paper. This paper investigated the effect of nonuniform tree-like fins on the melting characteristics of phase change units. The topology domain is achieved based on a density-based optimization methodology, with a heat source varying along the vertical direction innovatively. Numerical results reveal that the tree-like fin structure is distributed within the design domain. The varying heat source induces more metal fins placed in the bottom part of the phase change unit. Topology fins are capable of reducing the unmelted "dead zone" appearing in the bottom corners of the no-fin or even-fin phase change unit. The balance between thermal transient conduction and convection reduces the total melting time of PCMs in the topology phase change unit approximately 52.78 % and 23.62 % when compared to the no-fin and even-fin cases. The phase change unit with nonuniformly topologized fins (n = 2) is optimal with fastest melting rate and lowest average temperature of PCM. Fin volume, tube-shell ratio and heat flux are found to have positive effect on phase transition of the phase change unit. The melting rate of phase change unit is significantly accelerated by an increase in fin volume, tube-shell ratio and heat flux. In conclusion, this paper illustrates the heat transfer enhancement of a phase change unit integrated with the nonuniform topology fins, with noticeable benefit to the optimal design of phase change system.