Study on the effect of different additives on improving the thermal conductivity of organic PCM

Graphite (Grp) powder, nano-silicon (Si) powder, nano-copper (Cu) powder, nano-tungsten (Wu) powder, and nickel (Ni) powder were selected as the additives in this study. Meanwhile, stearic acid (SA), paraffin wax (P), and a P-SA mixture were added in 5%, 15%, 30%, and 50% proportions, to prepare 63 combinations of composite Phase Change Materials (PCM). The variation of thermal conductivity of the 63 sorts of composite PCM were studied experimentally. The aim of study was to understand the impact of the five additives on the thermal conductivity of the PCM. The results show that each of the additives can facilitate in the thermal conductivity of the PCM, and through 500 heating and cooling cycles, the fluctuation range is still less than 10%. Among the additives tested, graphite powder displayed the best performance. The addition of tungsten powder to the PCM resulted in poor fusibility, and the lowest increase in thermal conductivity.