以三水醋酸钠(CH3COONa.3H2O)为相变储热基材,添加各种不同成核剂和增稠剂,比较它们的效果,寻求储热性能优越的组合配方。实验表明:对于同一成核剂,随添加量的增加,CH3COONa.3H2O的过冷度有增大的倾向。在10 g CH3COONa.3H2O中添加0.05 g的Na2HPO4.12H2O,抑制过冷的效果最好,同时配合0.3 g羧甲基纤维素(CMC)使用,CH3COONa.3H2O的过冷性能得到进一步改善,过冷度可降低至2.015℃,并且还能有效地防止相分层。同时,还发现CH3COONa.3H2O体系的恒温温度为65℃比较合适。
A accelerated arithmetic algorithm of the dynamic computing regions was designed,and 3-dimensional numerical simulation of isothermal solidification for a binary alloy was implemented.The dendritic growth and the recalescence of Ni-Cu binary alloy during the solidification at different cooling rates were investigated.The effects of cooling rate on dendritic patterns and microsegregation patterns were studied.The computed results indicate that,with the increment of the cooling rate,the dendritic growth velocity increases,both the main branch and side-branches become slender,the secondary dendrite arm spacing becomes smaller,the inadequate solute diffusion in solid aggravates,and the severity of microsegregation ahead of interface aggravates.At a higher cooling rate,the binary alloy presents recalescence;while the cooling rate is small,no recalescence occurs.
