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高温熔盐作为一种高效的传热和蓄热工质,其熔点的高低和熔化潜热的大小决定着熔盐的工作温度和相变蓄热能力。以化学纯Na Br、KBr、CaBr_2、LiBr为基盐,按照一定比例配制一种混合四元溴化盐。为改善该混合熔盐的性能,将纳米SiO_2以一定质量分数均匀加入混合溴化盐中,配制得到SiO_2纳米溴化盐。利用同步热分析仪对四元溴化盐和SiO_2纳米溴化盐的熔点和熔化潜热进行实验研究。实验结果表明纳米溴化盐的熔点随纳米SiO_2质量百分含量的增大而缓慢下降,下降幅度在2.5℃以内;熔化潜热随纳米SiO_2质量百分含量的增大呈近似直线规律升高,当纳米SiO_2含量达到1.5%时,该纳米SiO_2溴化盐的熔化潜热达到最大,较四元溴化盐升高了89.6%;纳米SiO_2的添加提高了四元溴化盐的分解温度及热稳定性。
High temperature molten salt as an efficient heat transfer and heat storage medium, the melting point of the level and the size of the latent heat of fusion determines the molten salt temperature and phase change thermal storage capacity. With chemical pure Na Br, KBr, CaBr_2, LiBr as the base salt, according to a certain proportion to prepare a mixed quaternary bromide. In order to improve the performance of the mixed molten salt, the nano-SiO 2 is evenly mixed with the mixed bromide salt in a certain mass fraction to prepare the nano-SiO 2 bromide. Simultaneous thermal analysis was used to study the melting point and latent heat of melting of quaternary bromide and SiO2 nano-bromide. The experimental results show that the melting point of the nano-bromide salt decreases slowly with the increase of the mass fraction of nano-SiO 2, and the decrease range is within 2.5 ℃. The latent heat of fusion increases linearly with the increase of nano-SiO 2 mass fraction, When the content of nano-SiO 2 reaches 1.5%, the latent heat of melting of nano-SiO 2 bromide reaches the maximum, which is 89.6% higher than that of quaternary bromide. The addition of nano SiO 2 increases the decomposition temperature and thermal stability of quaternary bromide .