Temperature-dependent thermal properties of solid/liquid phase change even-numbered n-alkanes: n-Hexadecane, n-octadecane and n-eicosane

摘要

The thermal conductivity (λ) and thermal diffusivity (a_T) of the solid/liquid phase change linear n-alkanes were measured simultaneously by the transient multi-current hot wire technique at atmospheric pressure in the range 258-348 K. The same set-up was used to measure λ and a_T of the liquid and the solid states at different electrical currents. Three n-alkanes, n-hexadecane (C_(16)H_(34)), n-octadecane (C_(18)H_(38)) and n-eicosane (C_(20)H_(42)) were studied. Differential scanning calorimetry was applied at the temperature range 248-348 K to determine the melting/crystallization temperature, the heat of melting/crystallization and the specific heat of both the solid and liquid phases. Some results were compared with available literature data. The density of the n-alkanes at liquid state was also measured at different temperatures and their thermal diffusivity was estimated and compared to that obtained by the hot wire technique. The cumulative energy stored was estimated over a definite range of temperature for the three n-alkanes and this was found to be hieher for eicosane.