ABSTRACT

Expanded graphite (EG)/LiCl-NaCl phase change composites are prepared by aqueous solution method with different EG amount and forming pressure to enhance heat conduction for high-temperature latent heat thermal energy storage application. Their microstructure and thermal conductivity are characterized. Results indicate that the composites are uniform and the LiCl-NaCl eutectic is well dispersed in the graphite flakes. Thermal conductivity of the LiCl-NaCl can increase to as much as 40.51 W/(m·K), which is 46 times higher than that of pure eutectic salt. With forming pressure, the thermal conductivities of the samples show anisotropy because of a flattened irregular honeycomb network of graphite. Within certain limits, the greater the forming pressure is, the more pronounced the anisotropy performs. In addition, the formulas to calculate the thermal conductivity in the axial direction and the radial direction are given based on the average rotation angle φ of EG basal plane, and experimental data show that the formula in the radial direction is especially useful for calculating the thermal conductivity.

摘要

采用水溶液法制备了不同EG量和成型压力的膨胀石墨（EG）/ LiCl-NaCl相变复合材料，以增强导热性，适用于高温潜热储热。表征了它们的微观结构和热导率。结果表明，复合材料是均匀的，并且LiCl-NaCl共晶体很好地分散在石墨薄片中。LiCl-NaCl的热导率可以增加到40.51 W /（m·K），是纯共晶盐的46倍。在成形压力下，样品的导热率显示出各向异性，这是由于石墨的扁平不规则蜂窝状网络变平了。在一定范围内，成型压力越大，各向异性表现得越明显。此外，