Preparation and thermal properties of porous heterogeneous composite phase change materials based on molten salts/expanded graphite

摘要

Three kinds of porous heterogeneous composite phase change materials were synthesized from expanded graphite (EG) and binary molten salts (LiNO_3-KCl, LiNO_3-NaNO_3 and LiNO_3-NaCl) through solution impregnation method. Binary molten salt content in the composite phase change materials was calculated to be between 77.8% and 81.5% and high encapsulation efficiency was calculated to be between 72.8% and 78.8%. The thermal conductivity of binary molten salts was enhanced by 4.9-6.9 times after impregnation with EG. SEM photographs showed that the prepared composites were more homogeneous in comparison to other salt/EG composites prepared by infiltration or compression. Phase change properties of the porous heterogeneous composite phase change materials showed great thermal stability, which was maintained after 100 cycles.