Preparation and performance of modified expanded graphite/eutectic salt composite phase change cold storage material

Abstract

Cold energy storage technologies using phase change materials (PCM) have received increasing attention these years. In this work, we develop a novel kind of composite PCM using modified expanded graphite (MEG) to adsorb K2HPO4·3H2O–NaH2PO4·2H2O–Na2S2O3·5H2O–H2O eutectic salt by impregnation method. Within 120 min, the adsorption capacity of MEG for eutectic salt is 75.33% higher than that of unmodified expanded graphite (EG). The composite PCM has a phase change temperature of −5.30 °C, a large latent heat of 161.8 kJ kg−1, and a low supercooling degree of 1.83 °C. The thermal conductivity of the composite PCM is 13.3 times as large as that of the eutectic salt. Moreover, the thermal cycle tests demonstrated excellent thermal reliability. These outstanding thermal properties endow K2HPO4·3H2O–NaH2PO4·2H2O–Na2S2O3·5H2O–H2O eutectic salt/MEG composite PCM with broad application prospects in the fields of beer industry, air conditioning refrigeration, refrigerator refrigeration and cold chain logistics.