To support the integration of high shares of renewable energy and enhance the operational flexibility of thermal power systems, thermosyphon have been considered as promising high-efficiency heat transfer components for thermal energy storage applications. In this study, a water-based thermosyphon motivated by molten-salt thermal energy storage scenarios is investigated numerically to clarify its internal heat-transfer behavior under different operating conditions. A two-dimensional CFD model is established based on the Volume-of-Fluid (VOF) multiphase approach coupled with the Lee phase-change model. The effects of heating power (3.5–5.0 kW) and liquid filling ratio (25–40%) on wall temperature distribution and thermal resistance characteristics are systematically analyzed. The results indicate that increasing the filling ratio improves the uniformity of the evaporator wall temperature, and a filling ratio of 40% leads to a relatively favorable liquid distribution and the lowest total thermal resistance within the investigated range. The evaporator thermal resistance exhibits a “decrease–increase” trend with heating power and reaches a minimum value of 1.019 × 10−4 K/W at 4.5 kW, while the condenser thermal resistance decreases monotonically with in-creasing heating power. This study provides comparative numerical insights into the coupled effects of heating power and filling ratio on thermosyphon performance, offering a reference for the component-level design and parameter selection of heat pipe heat exchangers in molten-salt-related thermal energy storage systems.
Ding et al. (Fri,) studied this question.