Numerical study on the effect of umbrella-shaped fins in charging performance of a latent heat storage unit

Branch fins can expand the heat exchange area and uniformly release heat to each part of phase change material (PCM) domain. It has advantages in accelerating heat storage speed, but its structure is too complex. Based on these, a novel two-stage branch umbrella-shaped fin was designed in current research, which not only simplified the structure but also maintained the advantages of uniform heat distribution. The transient melting model of PCM in the umbrella-shaped fins latent heat storage unit was established and the numerical simulation was conducted. The influence of bifurcation number on melting was studied. Based on the optimal number of bifurcations, the non-uniform arrangement method was applied to further accelerate the melting of PCM, and the best optimal filling ratio was gotten. The results showed that as the bifurcations increased, the natural convection was weakened, and the thermal conduction was strengthened. When the bifurcation number was 4, the PCM melted more quickly and the temperature field was more homogeneous. Melting time can be reduced by 61% compared with straight fins. The heat conduction of PCM is weakened and the convection is strengthened with an increase in filling ratio. The melting speed of PCM first decreased and then increased. When the filling ratio was 345 degrees, PCM had the fastest melting speed and the most uniform temperature field, and the melting time can be reduced by 9.6% compared with the uniform arrangement.