Measurement of the Thermal Diffusivity of n-Dodecane at Temperatures from 290.15 to 633.15 K and Pressures up to 5.0 MPa

n-Dodecane is one of the key components of aviation kerosene. Although thermal conductivity data for n-dodecane is quite abundant, direct measurements of thermal diffusivity remain scarce, particularly in the vicinity of the aviation kerosene critical point. In this work, we measured the thermal diffusivity of n-dodecane using dynamic light scattering method in a temperature range of (290.15–633.15) K along seven isobars at p = (0.1, 1.0, 1.5, 1.8, 2.0 2.5 and 5.0) MPa and analyzed the thermal diffusivity as affected by temperature and pressure. The relative combined uncertainty of the thermal diffusivity experimental system is estimated to be 0.026 at a coverage factor of k = 2 with the level of confidence 0.95. The polynomial correlation of the thermal diffusivity against the temperature and pressure was proposed. The absolute average relative deviation and maximum relative deviation between the calculated results and experimental data are 0.68% and 2.98%, respectively. This study accurately measured the thermal diffusivity over a wide temperature range. It is expected to fill the gap in the existing literature and provide support for the exploration of the near-critical zone phenomenon.