Figure (10) displays the temperature contour over time during the
solidification process. Initially, the temperature of the melted PCM
decreases, causing the hotter PCM to rise to the top. The overall
temperature of the melted PCM reaches the solidus temperature, achieving
a uniform temperature distribution at around 500 seconds for all three
models. At this stage, a solid layer forms on the fin surface. The
temperature of this layer decreases to match the heat transfer fluid
temperature during solidification, and the layer width gradually
increases until full solidification is achieved.
Figure (11) displays the temperature versus time graph, showing the
volume averaged PCM temperature over time. Two distinct regions are
observed. The first region is characterized by a rapid decrease in
temperature over time, primarily driven by sensible heat transfer from
the PCM. This region concludes at around 500 seconds, corresponding to
stage one in the temperature contour. The second region exhibits a
gradual decrease in temperature over time due to heat transfer by latent
heat, continuing until the end of the test.
There are slight differences among the three models, with Model A-1
having slightly lower temperatures at certain instances, particularly at
the beginning of region two. Model A-2, on the other hand, features the
highest temperatures in region two.