Shape–stabilized phase change materials composed of polyethylene glycol and ordered mesoporous silica synthesized from fly ash

Abstract

Aiming at the problems of easy leakage and low thermal conductivity of solid–liquid phase change materials (PCM), and the recycle of fly ash, ordered mesoporous silica (OMS) was synthesized from fly ash to prepare the shape–stabilized PCM (SSPCM) with various polyethylene glycol (PEG) mass fractions. Aminoated multi–walled carbon nanotubes (MWNT–NH2) were added into SSPCM for enhancing the heat transfer rate. The structure of PEG remains intact after blending with OMS. The shape–stabilization capacity of OMS to PEG was up to 90 wt%. The leakage problem of solid–liquid PCM can be effectively solved owing to the interactions between OMS and PEG, such as surface adsorption, mesoporous confinement and hydrogen bonding. The melting enthalpy of PEG/OMS SSPCM with 90 wt% PEG reaches up to 133.7 J g−1, and its heat storage efficiency is 90%. SSPCM exhibits excellent thermal stability and reliability. Its thermal conductivity is increased by 191.3% upon the addition of 5 wt% MWNT–NH2 comparing with PEG.