Research on Heat Transfer Characteristics of a Coupled System of Molten Salt Heat Pipe and Thermoelectric Power Generation

Abstract: This study aims to validate the design scheme, key technologies, and system integration capabilities of a molten salt reactor by constructing a high-temperature heat pipe heat transfer experimental platform. The focus is on investigating the startup characteristics of the heat pipe and the coupled heat transfer dynamics within a thermoelectric power generation system. Methods​: A high-temperature heat pipe experimental apparatus was developed, utilizing molten salt (a ternary nitrate mixture with a melting point of 230°C) as the primary heat transfer medium. The system was initiated via a ​hot-condition salt-loading startup method​ to simulate operational conditions, with temperature monitoring achieved through K-type thermocouples and pressure sensors. A thermal resistance network model was established to analyze heat transfer pathways, incorporating radiative and convective effects quantified at 700°C. Experimental protocols included:1.Startup phase: Gradual heating from ambient to 700°C with molten salt loading under controlled nitrogen atmosphere; 2. Steady-state operation: Measurement of thermal conductivity, heat flux, and thermoelectric voltage output using a T-type differential thermopile;3. Model validation: Comparative analysis between experimental data and thermal resistance network predictions. Results​:The experimental results demonstrate that the ​equivalent thermal conductivity of molten salt​ reaches ​11.2 W/m·K at 700°C, driven by enhanced radiation heat transfer (contributing 63% of total heat flux) and natural convection. The thermal resistance network model exhibited a ​44.9% deviation​ from experimental data in overall system analysis, primarily due to unaccounted interfacial thermal resistances. However, the model’s prediction for the ​molten salt heat pipe thermal resistance​ showed only a ​19.3% discrepancy, confirming the feasibility of integrating thermal resistance network methods with experimental validation. Systematic thermal analysis revealed that the ​thermoelectric power generation system​ accounts for ​87.3% of total thermal resistance (0.51 K/W), emphasizing its dominant role in heat transfer inefficiency.
The experimental results demonstrate that the equivalent thermal conductivity of molten salt reaches 11.2 W/m·K at 700°C, driven by enhanced radiation heat transfer (contributing 63% of total heat flux) and natural convection. The thermal resistance network model exhibited a 44.9% deviation from experimental data in overall system analysis, primarily due to unaccounted interfacial thermal resistances. However, the model’s prediction for the molten salt heat pipe thermal resistance showed only a 19.3% discrepancy, confirming the feasibility of integrating thermal resistance net-work methods with experimental validation. Systematic thermal analysis revealed that the thermoelectric power generation system accounts for 87.3% of total thermal resistance (0.51 K/W), emphasizing its dominant role in heat transfer inefficiency.