Design and optimization of latent heat energy storage units with tree-shaped fins
Gao, Qingbo (2025)
Kandidaatintyö
2025
School of Energy Systems, Energiatekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2025051545103
https://urn.fi/URN:NBN:fi-fe2025051545103
Tiivistelmä
This thesis focuses on the design and numerical evaluation of a latent heat energy storage device using dendritic (tree-shaped) fins for heat transfer enhancement. The main contributions include:
(1) The heat transfer performance during the melting process of the phase change material can be significantly improved through appropriate geometrical configurations. With fixed bifurcation angles, the most effective configuration employing a gradient branch length distribution reduced the melting time by 18.4% compared to the reference case. With constant branch lengths, a moderate increase in bifurcation angles led to a 3.3% reduction in melting time.
(2) Under gravity, all configurations exhibited preferential melting in the bottom region. The ‘V-shaped’ channel design, with a bifurcation angle aligned with the direction of gravity, achieved a liquid-phase fraction of 88.1% at 2400 s, suggesting a potential method for directional heat transfer enhancement.
(3) The study reveals the dynamic balance of multimodal heat transfer and the stage-dependent influence of the bifurcation angle. Maintaining a 50° bifurcation at the root ensures sufficient fin coverage, while a 30° angle in the secondary branches helps to keep the flow channel open.
These results provide practical insights for the design of efficient latent heat energy storage systems incorporating dendritic fin structures.
(1) The heat transfer performance during the melting process of the phase change material can be significantly improved through appropriate geometrical configurations. With fixed bifurcation angles, the most effective configuration employing a gradient branch length distribution reduced the melting time by 18.4% compared to the reference case. With constant branch lengths, a moderate increase in bifurcation angles led to a 3.3% reduction in melting time.
(2) Under gravity, all configurations exhibited preferential melting in the bottom region. The ‘V-shaped’ channel design, with a bifurcation angle aligned with the direction of gravity, achieved a liquid-phase fraction of 88.1% at 2400 s, suggesting a potential method for directional heat transfer enhancement.
(3) The study reveals the dynamic balance of multimodal heat transfer and the stage-dependent influence of the bifurcation angle. Maintaining a 50° bifurcation at the root ensures sufficient fin coverage, while a 30° angle in the secondary branches helps to keep the flow channel open.
These results provide practical insights for the design of efficient latent heat energy storage systems incorporating dendritic fin structures.