Investigation on improving the heat exchange efficiency of an ocean thermal engine with snowflake-like fins

The low melting efficiency of ocean thermal engines limits the sampling rate of buoys driven by ocean thermal energy. To address this issue, an innovative snowflake-type fin has been integrated into the thermal unit of an ocean thermal energy conversion power generator. A numerical investigation was conducted to analyze the effects of fin configuration, bifurcation angle θ, spacing L, and length ratio α on the melting behavior and thermal storage performance, with maintaining a constant total fin volume held constant throughout the study. The results indicate that the snowflake configuration significantly reduces the complete melting time of the phase change material (PCM). Furthermore, the melting time exhibits a trend that initially decreases before subsequently increasing. Using response surface methodology, the optimal conditions for single-factor optimization with a fixed total fin volume were determined to be θ1 = 123°, θ2 = 113°, L20 = 6.78 mm, and α = 0.648, achieving the shortest melting time. Under these optimized conditions, the melting time was reduced by 34.8% compared to traditional multi-level fin configurations. This paper proposes a method for optimizing PCM melting and thermal storage performance through the utilization of a snowflake configuration.