云遮挡条件下熔融盐吸热管防护的数值模拟

基于吸热器单管模型，采用Fluent数值软件模拟研究云遮挡发生时及防护后，不同热流密度、熔融盐流速、表面对流换热系数吸热管温降特性的影响。研究结果表明：辐射热流密度对于熔盐吸热管壁面温度降低至接近凝固点的时间影响有限；对流换热系数越大越容易出现熔盐凝固；熔盐进口流速越低，熔盐出口温度降低至接近凝固点的时间越长；单根吸热管壁面温度下降至熔盐最低使用温度时间约为20 s，采用加装防护装置及降低熔盐进口流速相结合的防护策略，可将其时间延长近6倍，最长延缓至143 s。

Numerical Simulations on the Protection of the Molten Salt Thermal Tube under Cloud Occlusion

Based on the single tube model of the receiver, the temperature drop characteristics of the endothermic tube such as the heat flux, molten salt flow rate and surface convection heat transfer coefficient were studied through numerical simulations on the scenarios under cloud occlusion before and after protection schemes implemented. The results exhibit limited impacts of radiation heat flux density on the elapsed time for temperature at the molten salt outlet to decrease to close to the solidification point. Moreover, the greater the convection heat transfer coefficient, the more likely the molten salt solidification may appear; while the lower the molten salt inlet velocity, the longer time it will take for the molten salt outlet temperature to drop close to the solidification point. Without the protective device, the time taken to reach the freezing temperature of the molten salt at the outlet is about 20 seconds. The scheme of adding the protective device and reducing the inlet velocity of molten salt can be applied to extend the time by almost six times, or as much as 130 seconds. Thereby system security can be greatly improved.