Thermal conductivity enhancement of PEG/SiO_2 composite PCM by in situ Cu doping

摘要

In order to improve the energy utilization efficiency during heat charging and discharging processes, thermal conductivity enhancement of polyethylene glycol (PEG)/SiO_2 hybrid form-stable phase change material (PCM) was achieved by in situ Cu doping via in situ chemical reduction of CuSO_4 through ultrasound-assisted sol-gel process. This method would be an important approach to develop novel hybrid form-stable PCM with high thermal conductivity due to the mild preparation conditions. The XPS result of this material showed that the valence state of copper in PEG6000/SiO_2 PCM was mainly zero. The FTIR demonstrated that there was no new chemical bond between Cu, PEG6000 and SiO_2. The thermal properties and thermal stability of the composite PCM were confirmed using DSC and TGA analyses. The phase change enthalpy of Cu/PEG/SiO_2 PCM reached up to 110 J/g, and the thermal conductivity was 0.414 W/(m K) for 2.1 wt% Cu in PEG/SiO_2, which was enhanced by 38.1% compared to pure PEG. The Cu/PEG/SiO_2 hybrid material had excellent thermal stability and good form-stable performance.