Research on modified expanded graphite/eutectic salt composite phase change material in cold chain transportation

Abstract

Attention to the use of phase change materials (PCMs) in cold chain transportation has increased in recent years. In this work, a form-stable composite phase change material (CPCM) prepared by a novel eutectic salt (Na2SO4·10H2O-MgSO4·7H2OH2O) PCM composite with modified expanded graphite (MEG) was investigated. The hydrophilicity of expanded graphite (EG) and its compatibility with the eutectic salts were improved by coating SiO2. The results showed that microstructure of the EG was maintained after modification, and adsorption of the PCM by the MEG was 55.23 wt% higher than that of the EG. The CPCM with 20 wt% MEG exhibit a high enthalpy of 180.8 J/g, the phase transition temperature of −5.6 °C and a high thermal conductivity of 5.183 W/(m·K). The thermal conductivity of CPCM was 8 times as large as that of the PCM. Moreover, the thermal performance of the CPCM was small change after 200 thermal cycling, exhibiting good thermal cyclic reliability. Besides, a potential application test of the form-stable CPCM was performed through a low temperature insulation box. It showed that form-stable CPCM can control sudden temperature fluctuation and maintain stable temperature for longer time inside the insulation box.