Optimization on a novel irregular snowflake fin for thermal energy storage using response surface method

In this study, the horizontal sleeve phase change heat storage unit filled with RT55 is taken as the research object. Providing at the low thermal conductivity of phase change materials (PCM), this work proposes using an irregular snowflake-shaped longitudinal fin structure to improve the melting performance of horizontal latent heat storage sleeves (LHTES) under natural convection and to numerically simulate the phase change heat transfer process. Here, Thermal assessments on the melting fraction, temperature field, velocity distribution, and heat storage for melting are made. Results demonstrate that the snowflake fin structure significantly shortens the full melting time of LHTES, saving 45.92% time compared to the traditional fin structure. This study reveals that moderate changes of fin length, width, shape, and distribution angle could shorten the heat filling time. As a result of aggregated evaluation of the heating time, heat storage capacity, and heat storage temperature, the study determined the optimal fin distribution angle α to be 40°. This work further optimized the geometric parameters using the response surface method (RSM) and proved that the optimal solution to be the fin end length at 13mm, the width at 0.58mm, and the bifurcation angle at 40°.