Performance Optimization of Molten Salt Thermocline Storage System with Coupling Thermal Resistance

Molten salt thermocline storage systems provide significant cost advantages for concentrated solar power, although their thermal performance is constrained by internal thermal resistance within solid fillers. This study establishes a coupled model integrating solid heat conduction and molten salt convection to analyze thermal resistance between molten salt and solid interfaces. System optimization evaluates key parameters including solid thermal conductivity, filler diameter, molten salt thermal conductivity, and inlet velocity. Results indicate that solid thermal resistance impedes solid‐salt heat transfer, with optimal solid thermal conductivity maximizing discharging efficiency. As filler diameter increases from 0.025 to 0.045 m, the optimal solid thermal conductivity rises by 3 W (m K) −1 , while the discharging efficiency decreases ≈1.8%. At the optimal solid thermal conductivity, moderate reduction of molten salt thermal conductivity increases discharging efficiency by 3.46%. Reduced inlet velocity further diminishes efficiency, requiring elevated molten salt thermal conductivity to enhance thermal performance at lower flow rates. These findings demonstrate that synergistic optimization of solid thermal conductivity and molten salt thermal conductivity under variable operating conditions can significantly enhance thermocline storage efficiency.