Graphene oxide – adipic acid nanocomposites for thermal energy storage: Assessment of thermophysical properties and energy storage performance

Abstract

Adipic acid is one of the organic phase change materials with a melting temperature greater than 150 °C and a freezing point greater than 140 °C, making the same a suitable thermal energy storage medium for near-atmospheric pressure steam generation. This work attempts to alleviate the rate limitation posed by the lower thermal conductivity of adipic acid by adding graphene oxide (GO) nanostructures at lower concentrations such that the energy storage capacity is not severely affected. The resultant GO – adipic acid composites (0–2 wt% GO) were characterized in terms of latent heat for phase change, specific heat and thermal conductivity. The composite containing 1 wt% GO exhibited a 16 % enhancement in thermal conductivity with a 3.4 % reduction in latent heat and 3.6 % reduction in specific heat. The impact of GO addition on the solidification rate was remarkable, with a 44 % enhancement in overall heat transfer coefficient during the initial solidification phase, when solidification was carried out in thermal contact with a constant temperature heat transfer fluid (oil bath). Thus, the present work clearly demonstrates the intensification of heat transfer during the discharge cycle of a thermal energy system with 1 wt% GO-Adipic acid composite as the thermal energy storage medium.