Large-scale fabrication of expanded graphite aerogel-based phase change material composite for efficient solar harvesting

Abstract

The low thermal conductivity, insufficient solar-to-thermal charging capacity, and poor shape stability of phase change materials (PCMs) restrict their functionality in solar harvesting. Herein, a novel large-scale expanded graphite-based aerogel (EGA) with high thermal conductivity and excellent solar harvesting capacity was fabricated by gel polymerization to load polyethylene glycol (PEG, a type of PCM). The developed EGA exhibited super hydrophilic and lipophilic properties, and its thermal conductivity reached 1.42 W/(m·K). The prepared EGA/PEG composite exhibited a PEG loading capacity of 80.1 %. The corresponding thermal conductivity increased to 3.74 W/(m·K), which was 1290 % higher than that of pure PEG. Simultaneously, the solar-to-thermal energy charging efficiency improved from 31.8 to 91.8 %. The economic and environmental benefit analysis results indicated that the static payback period of applying the EGA/PEG composite to solar harvesting for domestic hot water supply was 1.7 years, and it exhibits significant potential advantages in alleviating green gas emissions.