Study on heat transfer characteristics during start-up of the external molten salt receiver considering wind effects in solar power towers

To investigate the impact of wind fields on the start-up process of the solar power tower system, this paper focuses on the complex convective heat transfer of the external molten salt receiver under varying wind speeds and directions. A three-dimensional numerical model is developed to analyze the convective heat transfer distribution under varying wind conditions. Subsequently, a new forced convection correlation at the panel level was developed to study the start-up performance of the receiver under varying wind conditions and molten salt flow rates. This correlation applies to receiver with height-to-diameter ratios of 0.90–1.20 and tube diameters of 33.4–51.0 mm, covering a temperature range of 286 K to 923 K. Unlike whole-receiver models, this approach is capable of describing panel-level convective variations and offers a practical correlation for similar external receivers within the studied parameter ranges. At v10 = 14 m s−1 during preheating, convective losses are 9 times radiative losses, making them the dominant energy loss mechanism. Under these conditions, if conventional preheating strategies (Vant-Hull algorithm) are employed, the minimum wall temperature only reaches 525 K, falling short of the 543 K required for successful preheating. Additionally, the temperature range of the panels can be as high as 96 K, posing a risk of solidification. Overall, for rapid engineering-scale prediction, this study provides a practical engineering-oriented approach for panel-level convective heat transfer modeling and offers useful guidance for the development of receiver start-up control strategies under complex wind conditions.