成核剂对储热材料Na_2HPO_4·12H_2O过冷性能的影响

Effect of nucleating agents on supercooling performance of heat storage material Na_2HPO_4·12H_2O

用步冷曲线法研究室温冷却环境下成核剂-Na2HPO4·12H2O复合体系的过冷性能,分析成核剂的添加量和晶体结构对过冷度的影响.结果表明:Na2SiO3·9H2O、NaF、CH3COONa·3H2O和Na2B4O7·10H2O这4种成核剂对Na2HPO4·12H2O的过冷现象有不同程度的改善.为有效改善过冷,成核剂的添加量有一个合适的范围.在10g的Na2HPO4·12H2O中,分别添加0.30g的Na2SiO3·9H2O、0.15g的CH3COONa·3H2O、0.05g的NaF和0.05g的Na2B4O7·10H2O时,抑制过冷的效果最好.同时发现,与Na2HPO4·12H2O晶体结构不同的成核剂Na2SiO3·9H2O改善过冷的效果最显著;与Na2HPO4·12H2O晶体结构相同的成核剂中,Na2B4O7·10H2O改善过冷的效果优于CH3COONa·3H2O.

The supercooling performances of nucleating agent-Na2 HPO4 · 12H20 composite system in room temperature environment was researched with step cooling method. The effect of nucleating agent addition amount and crystal structure on the supercooling degree was analyzed. The experimental results showed that four kinds of nucleating agents such as Na2SiO3 · 9H2O, NaF, CH3COONa ·3H20, and Na2B40,· 10H20 would improve the supercooling phenomenon of Na2 HPO4 · 12H2O to some extent. In order to improve the supercooling effectively, there is an appropriate range of nucleating agent addition a- mount. When adding 0. 30 g of Na2SiO3 · 9H20, 0. 15 g of CH3COONa · 3H20, 0. 05 g of NaF, and 0. 05 g of NazB4 O7 · 10H20 respectively into 10 g of Na2 HPO4 · 12H2 O, the inhibiting effect of supercoo- ling would be the best. Meantime, it was discovered that the nucleating agent Na2 SiO3 · 9H2 O with dis- tinct crystal structure from the Na2 HPO4 · 12HPO would have the most remarkable effect of improvement on the supercooling inhibition. The crystal structures of nucleating agents Na2B407 · 10H2O and CH3 COONa · 3H3O were identical to that of Na2HPO4 · 12H20,but Na2B407 · 10H2O would be better for improving the supercooling than CH3COONa · 3H2O.