A rotunda-shaped carboxymethylcellulose/carbon nanotube aerogel with three-dimensional network is constructed by freeze casting with special mold, and then impregnated with PEG. The obtained composite phase change materials have an enthalpy of 183.21 J/g, and a thermal conductivity of 0.324 W m⁻¹ K⁻¹, which is 57 % higher than that of the pure PEG.

Abstract

For the drawbacks of phase change materials such as poor shape stability and weak solar-thermal conversion ability, a rotunda-shaped carboxymethylcellulose/carbon nanotube aerogel (CA) with three-dimensional network was constructed by freeze casting with a special mold, and then impregnated with polyethylene glycol (PEG) in this work. The PEG/CA had an enthalpy of 183.21 J/g, and a thermal conductivity of 0.324 W m⁻¹ K⁻¹, which was 57 % higher than the pure PEG. The ability of PEG/CA to convert solar energy to thermal energy was a positive correlation between the inclusion of CNTs and the composite material‘s thermal conductivity. Under simulated sunlight, its solar-thermal conversion efficiency reaches 94.41 %, and after 10 min of irradiation, the surface temperature can reach 65 °C and the internal temperature can reach 44.67 °C. This rotunda-shaped PEG/CA is promising for the efficient use of renewable solar energy due to its strong solar-thermal conversion and thermal storage capabilities.