Analysis and Optimization of the Opening Dynamic Characteristics of Molten Salt Check Valves for Concentrating Solar Power

Abstract

The poor opening dynamic characteristics of molten salt check valves, used in concentrating solar thermal systems, constitute the main cause of valve disc oscillation and low pressure difference difficulty in opening during molten salt delivery. A molten salt swing check valve is designed to meet the requirements of high-temperature and high-pressure sealing and anti-crystallization flow channels. A transient dynamics model of the valve motion components is established, dynamic mesh and UDF (user-defined function) techniques are used to simulate the non-constant flow of hot molten salt and the opening process of the check valve and to analyze the dynamic characteristics of the opening process. Topological optimization of the valve motion components is proposed for the first time in order to improve the opening performance of the check valve, and the topological optimization of the valve motion components is based on the solid isotropic material penalty (SIMP) model with the variable density method and thermal–fluid–mechanical coupling method. The design is also verified for the dangerous working condition of a molten salt hammer. The results show that the mass of the valve motion component is reduced by 57.76% after optimization while meeting the requirements of strength and stiffness. The optimized molten salt check valve achieves a larger angle and faster opening, the full opening angle is increased by 6°, the positive resting pressure difference of the valve is reduced by 5 kPa, the minimum opening pressure difference is reduced by 8.9 kPa, the optimized flow characteristics are smoother, and the valve disc oscillation problem is avoided. The study provides a method for researchers to use to optimize the design of a molten salt swing check valve and its dynamic characteristics for concentrating solar power, which is of great significance in efforts to improve the stability of the molten salt transport system.