Experimental and numerical simulation of phase change process for paraffin in three-dimensional graphene aerogel

In this paper, melting and solidification experiments were performed on paraffin and paraffin/graphene aerogel (GA) composite. Since phase change process of paraffin in GA skeleton with micron-sized pore structure was difficult to directly observe, numerical simulation was applied with volume average method. The characteristics of phase change process for paraffin and paraffin/GA composite were clearly demonstrated. The temperature-time curves of experimental and numerical simulation were in good agreement. For the melting process, the strong natural convection of paraffin led to uneven temperature distribution. Paraffin cannot be completely melted due to its low thermal conductivity and poor heat exchange performance. GA skeleton could improve the thermal conductivity of paraffin and made it melt completely under the condition of heat exchange with the surrounding environment. For the solidification process, the heat transfer mode was mainly heat conduction, and the GA skeleton reduced the solidification time of paraffin by 21%. Three-dimensional porous structure of GA accelerated heat transfer process, which meant it can be used in the fields of heat storage. The micron-sized pore structure weakened the natural convection, indicating that heat transfer process of paraffin had uniform temperature distribution and could be applied in temperature management.