关键词: 太阳能, 碳酸熔盐, 复合材料, 镁粉, 制备, 热导率, 液体

Abstract:

In order to improve the low thermal conductivity performance of carbonate molten salt, it is proposed to dope metal magnesium powder with ternary carbonate molten salt (Li₂CO₃-Na₂CO₃-K₂CO₃) to strengthen the thermal conductivity. The static melting method was used to prepare the composite carbonate salts with 1%(mass) or 2%(mass) magnesium powder. The morphology, structure, liquid density, specific heat capacity, and thermal diffusivity were characterized by the scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDX), Archimedes method, the differential scanning calorimeter (DIN specific heat measure standard) and the laser flash method, respectively. The thermal conductivity was finally calculated based on the density, specific heat capacity, and thermal diffusivity. The results showed that the introducing of magnesium powder changed the morphology of pure eutectic (ternary carbonate salt), a large number of spherical particles (2-5 μm) were detected in the composite salts. Comparison with the pure eutectic, the liquid density, thermal diffusivity and thermal conductivity of salt compound doped magnesium powder were enhanced, and the liquid specific heat capacity was diminished. The mean thermal conductivity of salt compound doped with 1% or 2% magnesium powder was enhanced by 21.67% and 19.07%, respectively. So, the 1% salt composite should be the promising HTF due to the enhancement of density, thermal diffusivity and thermal conductivity.

Key words: solar energy, carbonate salt, composites, magnesium powder, preparation, thermal conductivity, liquid