添加纳米SiO_(2)熔盐传热储热稳定性能研究

Study on thermal stability of molten salt composites added with SiO_(2)nanoparticles

纳米熔盐具有优异的传热储热性能,但作为储热传热工质,要经历无数次储热/放热循环过程,因此纳米熔盐储/放热循环的稳定性非常重要。采用高温熔融法制备了不同配比的纳米熔盐,并利用自行设计的储热材料储/放热性能测试实验台进行冷热循环稳定性试验,间隔取出被测样品,采用差示扫描量热法和激光闪射法对其熔点、潜热、热重、比热和热导率进行试验测试,得到了该纳米熔盐储热材料在储/放热循环过程中的热物理性质随循环次数和成分配比的关系。分析发现添加质量分数1.0%的SiO_(2)纳米熔盐熔点更低,可操作的温度范围更广,储热系统所需的经济成本更小;添加质量分数0.5%SiO_(2)的纳米熔盐比热容与其他配比的纳米熔盐相比性能更优。

Molten salt nanofluid shows excellent performance in heat transfer and storage,but its thermal stability in heat storage/release process is crucial since the material has to undergo numerous similar cycles once it is taken as heat transfer and storage medium.Molten salt composites with different formulations were prepared by high-temperature melting method,and their heat storage/release performance was tested on a self-designed test bench.The measured samples were taken at a same time interval,and their melting point,latent heat,thermogravimetry,specific heat and thermal conductivity were tested by differential scanning calorimetry and laser flash.The relationship of the thermophysical properties of the molten salt composites with their ingredients and the number of heat storage/release cycles were obtained.It is found that the composite added with 1.0%SiO_(2)has a lower melting point,a wider temperature range for operation,and requires a lower investment in the thermal storage system,while the composite added with 0.5%SiO_(2)has a better specific heat capacity than those of other composites with SiO_(2)of different ratios.