Experimental investigation on thermal behavior of graphene dispersed erythritol PCM in a shell and helical tube latent energy storage system

Thermal conductivity of the Phase Change Materials (PCMs) of latent heat storage systems is enhanced by dispersing nanoparticles in base PCM for increased heat transfer rate. Heat transfer characteristics of the newly developed erythritol PCM dispersed with 1 wt% graphene nanoparticles in a newly designed shell and helical tube storage tank during charging and discharging processes was investigated. Both melting and solidification fronts progressed from the outer wall of the shell towards the axis on either side of the axis of the shell due to the helical tube arrangement. At the middle and near the axis of the storage tank, NDPCM melting time was decreased by 21% when inlet temperature of the hot therminol oil was increased from 160 degrees C to 180 degrees C and by about 30% when the oil flow rate was increased from 0.5 kg/min to 2 kg/min. Further, NDPCM solidification time was reduced by 11% when the cold therminol oil inlet temperature was decreased from 45 degrees C to 30 degrees C and by 20% when the oil flow rate was increased from 0.5 kg/min to 2 kg/min. Complete charging and discharging periods of NDPCM was reduced respectively by 20% at an inlet temperature of 180 degrees C and by 6% at an inlet temperature 30 degrees C for 1 kg/min flow rate of therminol oil compared with pure erythritol. This research study confirmed that the helical tube flow of heat transfer oil facilitated more uniform and quicker phase transition of PCM and graphene nanoparticles dispersed erythritol (NDPCM) had superior heat transfer behavior as compared to base erythritol and it can be utilized as a potential PCM for medium temperature thermal energy storage applications.