Thermal performance of PEG-MWCNTs composites as shape-stabilised phase change materials for thermal energy storage

Abstract

The development of phase change materials (PCM) for thermal energy storage is a promising technology. However, the liquid PCM leaks and low thermal conductivity limit the practical PCM applications. This article aims to solve these problems; it presents the preparation and thermal characterisation of PCM enhanced by carbon-based nanoparticles. The polyethene glycol 6000 (PEG 6000) is used as PCM and multi-walled carbon nanotubes (MWCNTs) as a shell matrix and thermal conductivity enhancer. The sample was prepared by the sonification method under vacuum conditions. Fourier transform infra-red spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA) tested the chemical and thermal compatibility of the prepared samples. The storage performances are tested by modulated differential scanning calorimetry characterisation. The nano-enhanced-PCM (NPCM) with 1 wt% MWCNTs showed excellent shape stability without any liquid leakage when the temperature was about 110 °C for 30 minutes. Drying method has a significant effect on the thermal storage capacity of the NPCM. The melting, solidification points and the latent heats of the NPCM were measured as 61.75, 35.50 °C, and 174.24, 167.84 J g−1, respectively. Meanwhile, the specific heat is 2.63 J g−1°C−1 for the solid-state and 2.14 J g−1°C−1 for the liquid-state. The thermal conductivity of pristine PEG was improved by 49%. Highlights PEG-MWCNTs shape-stabilised phase change materials were prepared through ultrasound-assisted vacuum method for efficient thermal energy storage. The thermophysical properties and thermal stability of the proposed NPCM has been analysed and discussed. The drying method highly influences the phase change temperatures and latent heats of the prepared NPCM. PEG adsorption into MWCNTs reached 99 wt% without leakage, and 1 wt% of MWCNTs enhanced the thermal conductivity by 49% and maintained good latent heat of 175 J g−1. The developed NPCM is an excellent potential candidate for electronic devices cooling applications.