纳米粒子掺杂太阳盐复合材料热物性研究

Study on thermophysical properties of solar salt composites doped with nanoparticles

在聚光式太阳能系统中,熔盐被视为良好的储热材料,具有成本低、使用安全、低饱和蒸汽压等特点。合理改善其热物性可实现太阳能高效利用,掺杂纳米颗粒可提高熔盐的储热及传热性能。在之前工作中,采用高温静态熔融法将纳米氧化铝(Nano alumina,NA2)掺杂于太阳盐(SS,质量分数为60%的硝酸钠与质量分数为40%的硝酸钾的混合物)中,获得了具有较高比热容的纳米流体(NA2-SS,N2S)。在此基础上,采用相同方法将纳米石墨粉(GP)和NA2同时掺杂于SS中(NA2-GP-SS,N2GS),利用差式扫描量热法和瞬态平面热源法对体系比热和导热进行测试。结果表明,优化样品为N2GS-4,比热容与原样SS相比提升21.79%,导热提升20.69%,在高温状态下具有较好的热稳定性。N2GS-4作为一种硝酸盐基纳米复合蓄热材料在热能存储系统中具有广阔的应用前景。

In concentrating solar energy system,molten salt can be regarded as good heat storage material with the characteristics of low cost,safe use and low saturated vapor pressure.Reasonable improvement of its thermal properties can realize the efficient utilization of solar energy.Doping nanoparticles can improve the heat storage and transfer performance of molten salt.In previous work,nano alumina(NA2)was doped into solar salt(SS,60%NaNO3+40%KNO3,mass ratio)by hightemperature static melting method to obtain nanofluids(NA2-SS,N2S)with high specific heat capacity.On this basis,nanographite powder(GP)and NA2 were simultaneously doped into SS(NA2-GP-SS,N2GS)by the same method.The specific heat and thermal conductivity of the system were measured by differential scanning calorimetry and transient plane heat source method.The results showed that the optimized sample was N2GS-4,its specific heat was 21.79%higher than the original SS,and thermal conductivity was increased by 20.69%,which had excellent thermal stability at high temperature.N2GS-4,as a kind of nitrate based nanocomposite thermal storage material,had a broad application prospect in thermal energy storage system due to its high thermal storage and heat transfer performance.