Experimental Determination of Temperature-Dependent Thermal Conductivity of Solid Eicosane-Based Nanostructure-Enhanced Phase Change Materials

The effective thermal conductivity of composites of eicosane and copper oxide nanoparticles in the solid state was measured experimentally by using the transient plane source technique. Utilizing a controllable temperature bath, measurements were conducted at various temperatures between 10 and 35°C for the solid samples. In the course of preparation of the solid specimen, liquid samples (0, 1, 2, 5 and 10 wt%) were poured into small diameter molds and were degased within a vacuum oven. The molds were then subjected to either ambient solidification or ice-water bath freezing method. Measured thermal conductivity data of the composites were found to be nearly independent of the measurement temperature for a given loading of CuO nanoparticles regardless of the solidification procedure. Irrespective of the solidification method, as the melting temperature was approached, thermal conductivity data of the solid disks rose sharply for both sets of experiments. The composites prepared using the ice-water bath solidification scheme consistently exhibited lower values of thermal conductivity when compared to the samples which prepared under ambient solidification method. This behavior might be due to the greater void percentage of ice-water bath samples and/or crystal structure deviations due to phase transition method.