Current research examines thermal power storage by thermosyphon amalgamated nanophase change material in thermal management systems. The experiments were analysed with heat inputs ranging from 40 to 90 W using deionized water, ethyl acetate, hydrofluoroether-7100, and n-propylamine as thermal fluids. The copper‑titanium nanocomposite particles at different concentrations (0.5, 0.3, 0.1, 0.08, and 0.05 wt%) are disseminated in a phase change material (methyl cinnamate). Due to its high thermal conductivity, a 0.5 wt% concentrated nanophase change material was used in this study. The heat transfer effectiveness, charging, and retrieving attributes of the nanophase change material are investigated using thermal fluids. The results indicate that hydrofluoroether-7100 has a lower thermal resistance, maximum heat transfer coefficient, and highest heat dissipation rate of about 0.26 K/W, 203.8 W/(m2‧K), and 98.9 %, respectively, at the maximum heat input. The low enthalpy of vaporization and surface tension are the causes of the acquired results. The maximum thermal power storage by the nanophase change material is 7.2 W during charging due to the influence of vaporized hydrofluoroether-7100 at 90 W, which is attributed to the increased vapor mass flow and shorter time required to reach the steady-state temperature of the melted nanophase change material. The overall exergy efficiency is greater in the case of deionized water and is 4.8 % owing to the greater temperature difference and heat loss. Moreover, the minimum possible power savings of approximately 6.2 % are obtained using the developed setup.