Three dimensional hybrid microcrystalline graphite-silica sol stabilized stearic acid as composite phase change material for thermal energy storage

Abstract

Solid-liquid phase change material (PCM) is widely investigated, however it's low thermal conductivity and leakage issue hinder its large-scale commercial application. Numerous researchers have taken different approaches to enhance its thermal property, and have verified the optimized performance of the newly developed series of PCMs through experimental data and simulation results. In this report we developed a form-stable composite with the three-dimensional (3D) hybrid structure matrix to tackle this issue. Microcrystalline graphite (MG) was used as the structure material, and silica sol was used as a binder and porous skeleton to design and prepare the microcrystalline graphite-silica sol matrix in a 3D hybrid structure. Stearic acid (SA) was introduced to the 3D hybrid matrix to form composite PCM. The effects of the mass ratio between MG and silica sol on the pore structure of the 3D hybrid matrix were investigated systematically. With increasing the mass content of silica sol in the hybrid matrix, the loading capacity increases followed by decreasing, with a maximum loading of stearic acid as high as 49.94 % observed. The composite PCM could achieve the highest melting/cooling latent heat of 95.76 J g−1/96.04 J g−1 and higher thermal conductivity by 90.9 % than pure SA. The thermal infrared image indicated that the optimized composite had a better transient temperature response than pure SA. The leakage test proved that the 3D hybrid matrix stabilizes SA well, exhibiting excellent shape stability during phase change. These results demonstrated that the composition of MG/silica gel is an effective strategy, giving enhanced energy storage characteristics, including thermal stability, energy storage capacity, and thermal reliability.