A novel method to predict thermal conductivity of NaCl/water based MCNT nano-suspesnion for cold energy storage
A novel method to predict thermal conductivity of NaCl/water based MCNT nano-suspesnion for cold energy storage
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一种预测用于冷能存储的 NaCl/水基 MCNT 纳米悬浮液热导率的新方法
DOI：
10.1016/j.egypro.2019.01.711
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Huang Y
中科院分区：
文献类型：
--
作者：
Huang Y
作为一种典型的低温蓄冷介质，NaCl-水溶液作为相变蓄冷材料（PCM），其熔点为-21 ℃。0.0625体积%- 0.5体积%将多壁碳纳米管（MCNT）通过超声分散在NaCl-水基液中制成纳米悬浮液。测定了MCNT-NaCl-水体系的粘度，实验结果与修正的Krieger-Doughnard（K-D）模型吻合较好。通过对粘度数据的拟合，得到了MCNT团簇的结构，表明温度越低，团簇的尺寸越大。利用MCNT团簇参数，采用修正的Hamilton-Crosser（H-C）模型预测了MCNT-NaCl-水体系的热导率。此外，还进行了导热系数实验，将测量值与计算值进行了比较。结果表明，传统的H-C模型低估了测量的热导率由大幅度的，而本文提出的方法显示出良好的精度。此外，还发现MCNT在低温下比在高温下更显著地提高导热系数。
As a typical cold storage media working at sub-zero temperature, NaCl-water solution as a phase change material (PCM) with -21oC melting point has been selected in this study. 0.0625 vol.%-0.5 vol.% multi-wall carbon nanotube (MCNT) was dispersed in the NaCl-water basefluid via ultra-sonicating to make nano-suspension. The viscosity of MCNT-NaCl-water was measured and the experimental results fitted well with the modified Krieger-Dougherty (K-D) model. The structure of MCNT cluster was derived from the fitting of viscosity data, showing that the lower the temperature, the larger the cluster size could be. Benefited from the MCNT cluster parameter, the thermal conductivity of MCNT-NaCl-water was predicted by modified Hamilton-Crosser (H-C) model, in which the MCNT cluster was considered as a whole part with its equivalent thermal conductivity. In addition, thermal conductivity experiment was also conducted to compare the measured value with the calculated value. The results indicated that the traditional H-C model underestimates the measured thermal conductivity by a large margin while the approach proposed in this paper shows good accuracy. Moreover, it is also found that MCNT will improve the thermal conductivity more significantly at low temperature than at high temperature.