Latent heat storage plays an important role in the utilization of solar energy. However

the low thermal conductivity of phase change materials (PCM) significantly reduces the heat transfer efficiency of latent heat storage systems. To enhance its storage/release efficiency

optimizing the fin geometry is essential. This paper establishes a validated three-dimensional numerical model that considers PCM natural convection to study the effects of fin height and number on the heat transfer process. The fin volume of all models is kept constant

and the fin height is determined by the annular space. The impact of fin heights (0.3

ΔR

0.5

ΔR

0.7

ΔR

0.9

ΔR

) and numbers (4

8

10

16) on heat transfer efficiency was investigated by analyzing the PCM temperature distribution on the shell section

the liquid fraction within the shell over time

and the average heat transfer rate and heat flux. The results show that increasing the fin height from 0.3

ΔR

to 0.9

ΔR

reduces the heat storage and release completion times by 61.16 % and 45.43 %

respectively. Similarly

increasing the number of fins from 4 to 16 reduces the heat storage and release completion times by 33.35 % and 31.13 %

respectively. The study concludes that increasing both the fin number and height dilutes the heat flux between the fin and PCM during

both the heat storage and release processes

with the fin number having a more significant effect on reducing heat flux than fin height. Therefore

when the fin volume remains constant

increasing fin height is more conducive to improving the heat transfer performance of the PCM. These findings will provide a foundation for the application of finned tube energy storage systems in building energy conservation and other fields.