Molten salt is one of the most commonly used heat storage working fluids in solar thermal power. However, its heat transfer coefficient is low. Optimizing the heat transfer condition could improve the heat transfer performance of molten salts, thereby facilitating convection that enhances heat transfer. In trough and tower solar thermal power generation systems, the heating surface of the molten salt collector tube differs with the different angles of sunlight heating. Numerical simulations on the characteristics of the flow and mixed convection heat transfer of Hitec salt in one-, two-, and three-sided heating conditions in pipes were carried out in this study. The results of mixed convection and heat transfer of molten salt on different multisided heating surfaces showed that the heat accumulated at the heating surfaces and then transferred to the mainstream core region. Under nonuniform heating conditions, the buoyancy effect generated a vortex, which changed the shape of the core area of the mainstream and resulted in the enhancement of the heat transfer ability. Double side heating showed the strongest buoyancy effect. The degree of heat accumulation under three-sided heating was the lowest, and the nonuniformity of the heat transfer process in one-sided heating was the highest.

熔盐是太阳能热发电中最常用的蓄热工质之一。但其传热系数较低。优化传热条件可以提高熔盐的传热性能，从而促进增强传热的对流。在槽式和塔式太阳能热发电系统中，熔盐集热管的受热面随着太阳光加热角度的不同而不同。本研究对管道内单侧、双侧和三侧加热条件下 Hitec 盐的流动和混合对流换热特性进行了数值模拟。熔盐在不同多边受热面上的混合对流和传热结果表明，热量在受热面积聚，然后转移到主流核心区域。在非均匀加热条件下，浮力效应产生涡流，改变主流核心区的形状，导致传热能力增强。双面加热显示出最强的浮力效应。三侧加热时的蓄热程度最低，单侧加热时传热过程的不均匀性最高。双面加热显示出最强的浮力效应。三侧加热时的蓄热程度最低，单侧加热时传热过程的不均匀性最高。双面加热显示出最强的浮力效应。三侧加热时的蓄热程度最低，单侧加热时传热过程的不均匀性最高。