Heat Transfer Enhancement and Structural Optimization of an N-Dodecane Based OTEC System for Arctic Profiling Floats

To address the power supply bottleneck of unmanned polar observation equipment, this study proposes and validates, for the first time, an Arctic Ocean Thermal Energy Conversion (OTEC) system using n-dodecane as the working medium. Distinct from conventional phase change materials (PCMs), n-dodecane demonstrates high compatibility with extreme polar cross-medium temperature gradients. A 3D transient phase-change heat transfer model was established and rigorously benchmarked against experimentally-grounded reference data. Results indicate that a 60 mm baseline tube diameter effectively balances energy storage potential and thermal lag. The optimized longitudinal fin configuration (LF-8) restructures the internal heat transport topology, substantially reducing solidification time by 87 min and boosting the normalized thermal discharging power to 187.5%. Compared to the 3–7 h required by conventional OTEC devices, the proposed LF-8 system demonstrates a significantly accelerated heat transfer rate. A comprehensive bivariate sensitivity analysis reveals that even under the absolute worst-case polar meteorological combination (−17 °C ambient temperature coupled with a sluggish 6 m/s wind), a complete thermodynamic reset is achieved in a maximum of 124.5 min. This safely preserves a substantial margin against the restricted 180-min surface-dwelling window. This research fills a critical gap in OTEC exploitation under polar conditions, providing a robust power solution for long-endurance Arctic profiling floats.