Strategy for improving temperature distribution uniformity in molten salt electric heaters: comprehensive optimization of operating parameters

Molten salt thermal storage technology has been widely applied in recent years for the flexible transformation of thermal power systems and consumption of renewable energy. Molten salt electric heaters (MSEHs) serve as key components of thermal-electrical decoupling in thermal storage systems. However, MSEHs are prone to local overheating and lack effective methods for adjusting operating parameters under variable conditions. The study developed a coupling model for MSEHs to optimize convective heat transfer performance and operating parameters. The results revealed that low heating power significantly alleviated overheating. Moreover, the study revealed how buoyancy effects dominate at low flow rates, leading to severe overheating and a maximum temperature of 657.72 °C. And the criterion based on the modified Rayleigh number for mixed convection onset of MSEHs was established. Additionally, empirical formulas for the MSEH flow and heat transfer characteristics were derived, enabling performance prediction without complex measurements. Finally, it was found that MSEH exhibited better temperature uniformity at lower flow rates and electric heating power under the same temperature rise conditions, with the maximum temperature reduced to 573.85 °C. And a neural network model predicting max temperature of MSEH was developed, providing a critical basis for real-time operational optimization under variable conditions.