Performance investigation of shell and helical tube heat energy storage system with graphene dispersed erythritol PCM

Experimental investigation on the thermal performance of a shell and helical tube latent heat thermal energy storage system for medium temperature applications is reported in the article. Commercial grade erythritol having a melting temperature of 120 degrees C was employed as the phase change material (PCM). The thermal conductivity of the erythritol had been usually very low (0.73W/mK) and it results in low heat transfer rates during both charging and discharging processes. In the study, an attempt was made, this inherent limitation of erythritol, high thermal conductive graphene nanoparticles, which are dispersed into erythritol matrix, referred to as nanoparticle dispersed phase change material (NDPCM). The effect of the addition of graphene nanoparticles on the performance of the storage system such as heat flow rate, overall heat transfer coefficient, charging and discharging efficiency and effectiveness was evaluated and compared with the storage system with only base erythritol during both energy storage and retrieval processes. The efficiency of the NDPCM system increased to 16.29% during the storage period and 28.48% during the retrieval period compared with the base PCM system. Further, it was observed that the effectiveness is about 14% greater at the beginning of the melting process and about 12% greater at the beginning of the solidification process for NDPCM.