Effect of compact fin structure on heat transfer performance of ice storage unit during freezing

•Ice storage technology applied to building energy efficiency.•A compact plate fin structure is proposed.•Parametric design optimization using numerical models.•The compact plate fin structure significantly strengthened the heat transfer.•Fin spacing, working medium channel number and outer space size are key parameters. Mismatches between energy demand and supply for buildings can be effectively solved by using ice storage technology. A compact plate-fin structured ice storage unit is proposed in this study, and its heat transfer performance is investigated through a combination of experimental verification and numerical simulation. A two-dimensional transient model of a plate-fin ice storage unit was developed and validated based on experimental data, and the heat transfer performance and solidification process of the unit were numerically simulated. The fin spacing, heat transfer fluid channel number and outer space size, which affect the phase transformation and solidification rate, were analysed. Results indicated that the compact fin structure considerably increased the heat transfer in the ice storage unit. Reducing the fin spacing, increasing the number of channels and decreasing the size of the external space can increase the solidification rate and improve the storage capacity of the ice storage unit. The full solidification time of the unit with a fin spacing of d = 4 mm was 32 % shorter than that with d = 24 mm. The solidification time with a channel number of N = 2 is 26 % shorter than that with N = 4. The final solidification time at f = 18 mm in the outer space is 57 % shorter than that at f = 33 mm.