Experimental study on charging and discharging performance of latent energy storage with topologically optimized fins: Diffusion and convection design

Guided by well-defined objective functions, the integration of topology optimization algorithms into the design of secondary heat exchange surfaces for latent thermal energy storage units can effectively mitigates the inherent low thermal conductivity of phase change materials. This approach significantly enhances both the thermal storage density and power density of the latent thermal energy storage units. In this study, a thermal diffusion topology optimization method and a thermal convection topology optimization method were developed, leading to the fabrication of two distinct topological fin structures: a "diffusion design" with a heat exchange area of 0.211 m2 and a "convection design" with a heat exchange area of 0.176 m2. The topology-optimized convection design exhibited superior heat transfer performance during both the charging and discharging processes. Compared to the conventional rectangular design, in which the volume fraction is the same as that in diffusion design and convection design, the diffusion design can reduce the total charging and discharging time by 52.2 %–58.6 % and 33.7 %–51.4 % respectively, while the convection design can reduce the total charging and discharging time by 61.0 %–69.4 % and 44.0 %–74.4 % respectively. Consequently, within a fixed fin structure and heat transfer area, variations in inlet flow rate and temperature of the heat transfer fluid offer limited influence over the heat transfer rate and overall system performance.