The three models were developed based on an understanding of natural convection in phase change material (PCM), drawing from previous studies. In these models, five fins were selected to achieve a balance between enhancement, reduced fin weight, and increased thermal storage capacity of the PCM heat exchanger (H.E.).
In the melting process, fresh molten PCM ascends to the top of the container, leading to an increase in the temperature of the upper half. Therefore, there is no need to increase the fin portion in the upper half. Conversely, during solidification, fresh cooled PCM descends to the bottom of the container, causing the temperature of the lower half to drop faster than that of the upper half. Therefore, adjusting the fin length distribution is crucial to achieve the optimal performance during both melting and solidification.
Considering these considerations, three designs were proposed:
  1. The first design features uniform-length fins and serves as the reference model for comparison. Figure (1) A.
  2. The second design, labeled A-2, has a greater fin portion in the lower half compared to the upper half of the container. Figure (1) B.
  3. The third model, A-3, also has a larger fin portion in the lower half, but it is less than that of the A-2 model. Figure (1) C.
Three-dimensional simulation models of a horizontal tabular phase change material (PCM) H. E. with five longitudinal copper fins were created. The dimensions of the components are presented in Table (1), and the length of the heat exchanger is 500 meters, as illustrated in Figure (2).