Experimental analysis of a graphene oxide-enhanced paraffin PCM

The research here presented aims at characterizing the thermal behaviour of a PCM-based latent heat storage enhanced with graphene oxide. The heat storage tank is composed of two PVC coaxial cylinders and a smooth stainless-steel helical heat exchanger installed inside the smaller one. The heat exchanger is immersed in PCM, a commercial paraffin with a melting temperature of around 28°C. The melting and solidification of the PCM were forced through hot or cold water flowing in the heat exchanger. The purpose is to explore the melting and solidification process by monitoring the temperature in the PCM with multiple thermocouples placed at different heights and different radial distances from the centre of the heat exchanger. Initially, the system was studied with pure paraffin. Then, two different mass percentages (i.e., 1.5% and 3%) of graphene oxide were added, whose high thermal conductivity had to counterbalance the paraffin low thermal conductivity and thus enhance the overall performance of the system. These three configurations were then compared to a reference scenario, consisting of the inner cylinder filled with pure water. The use of graphene oxide has increased the heat flux by up to 24% during heating and up to 31% during cooling compared to the pure PCM.