碳纳米管水悬浮液过冷度及非等温结晶过程

Supercooling behaviour and non-isothermal crystallization processes of aqueous suspensions of carbon nanotubes

采用添加碳纳米管形成悬浮液的方法可以有效地提高基液的导热系数,碳纳米管的存在还将对悬浮液的固液相变行为产生可观的影响。利用差示扫描量热仪对低浓度碳纳米管水悬浮液的过冷度进行了非等温结晶实验测试,对比分析了不同浓度(质量分数最高为1%)的悬浮液在不同降温速率情况下过冷度的变化规律。实验结果表明,由于碳纳米管的存在,悬浮液的过冷度较之纯水有所降低。随着浓度的提高,悬浮液的过冷度呈逐步下降的趋势。在最高浓度1%时,悬浮液的过冷度较之纯水下降了约7℃。此外,悬浮液的过冷度随着降温速率的增大略有升高,其中浓度为0.01%的悬浮液在降温速率为10℃/min时较2℃/min时增大了约4℃。采用碳纳米管悬浮液作为蓄冷工质对整个非等温结晶过程并未体现出加速的效果,但能在较慢的降温速率下有效地降低水的过冷度。

This paper reports a study on the supercooling behaviour and non-isothermal crystallization processes of dilute aqueous suspensions of carbon nanotubes. A differential scanning calorimeter （DSC） was used in the study. The dependence of the extent of the suspension supercooling was measured as a function of nanotube concentration and cooling rate. It was found that the extent of supercooling of water decreased due to the addition of carbon nanotubes and the extent of decrease increased with increasing carbnon nanotube concentration. The decrease in the supercooling was nearly 7 ℃ at a concentration of 1%. An increase in the cooling rate led to a slight increase in the extent of supercooling. Although the use of carbon nanotubes was able to reduce the extent of supercooling, it did not show any influence on the non-isothermal crystallization processes.