Sadegh Motahar - Faculty of Engineering, University of Shahreza
Rahmat Khodabandeh - Department of Energy Technology, KTH Royal Institute of Technology, Sweden

In the present paper, an experimental assessment was performed on the transient thermal performance of a heat sink filled by a phase change material (PCM) and PCM embedded with carbon nanofibers (CNFs) and titania (TiO۲) nanoparticles as nanostructured materials. In order to enhance the thermal conductivity of PCM, CNFs and TiO۲ nanoparticles at different loadings (۰.۵wt. % and ۲ wt.% of CNFs and ۲ wt.% and ۴ wt.% TiO۲) were dispersed by two-step method in to the molten PCM. The thermal conductivity and viscosity measurements showed an enhancement in composite thermal conductivity as well as an increment in viscosity. The heat sink was filled with PCM, PCM/CNF and PCM/TiO۲ and experiments were accomplished by inputting power ranging from ۳ W to ۸ W. Results showed that filling the heat sink with PCM delayed the time to reach a typical temperature of ۳۵°C by up to ۱۱۰% for the power level of ۸ W, while adding ۲ wt.% of CNFs reduced this time by ۱۵% and ۴ wt.% of TiO۲ nanoparticles improved by ۲%. Generally, dispersion of TiO۲ led to lower heat sink transient temperatures. However, adding ۲ wt.% of CNFs and ۴ wt.% TiO۲ nanoparticles in to PCM at power level of ۸ W raised the steady operation temperature by ۱۱°C and ۰.۳°C, respectively.

heat sink, PCM, nanostructured material, thermal conductivity, transient operation