Thermal Conductivity Enhancment of Solid Eicosane-Based Silver Nanostructure-Enhanced Phase Change Materials for Thermal Energy Storage

Abstract

In this thesis, thermal conductivity of eicosane-based PCM was enhanced by suspending highly-conductive silver nanoparticles resulting in the formation of nanoparticle-enhanced PCM (NePCM). Eicosane (C20H42) was selected as the base PCM, while Silver (Ag) was chosen as the additive. Three batches of solid eicosane-silver samples with distinct mass fractions (0, 1, 2, 3.5, 5, 6.5, 8 and 10 wt%) of nanoparticles were obtained under three different solidification routes: ice-water bath, room temperature and oven solidification. The transient plane source technique (TPS) was used to measure thermal conductivity at different temperatures starting at 10 °C and ending close to the melting point of each sample. Results showed an increase in the value of thermal conductivity as the temperature increased, and when close to melting point, a sharp rise in thermal conductivity was observed. Also, the oven solidification route samples exhibited the highest values while the ice-water samples showed the least increase. Furthermore, after a 2 wt% loading of Ag nanoparticles, a non-monotonic relationship was obtained between thermal conductivity and the weight fraction of Ag nanoparticles, regardless of the method of solidification. In addition to thermal conductivity measurement, the latent heat of fusion of the sample was investigated, utilizing differential scanning calorimetry (DSC). Results showed a decrease in the latent heat and the melting point of the NePCM as the additives loading increased due to the decrease in the number of molecules of eicosane in the samples.