Thermal diffusivity measurements using insulating and isothermal boundary conditions

Many methods exist to measure thermal diffusivity using either steady state or transient techniques. Steady state methods yield large experimental error and inaccuracies. Transient techniques, namely, the laser flash method, are expensive and require specialized equipment and advanced data analysis. In this paper, a novel experimental setup is devised to evaluate thermal diffusivity. In this experiment hot isothermal and insulating boundary conditions are imposed on a flat disk sample. The transient temperature profile of the insulated side of the sample is analytically similar to a classic time constant formulation. The thermal diffusivity is proportional to the inverse time constant. This method hosts a variety of advantages over other methods such as accuracy comparable to other methods, low cost, integrated modeling of interface effects, and small sample size. Several materials with low to medium thermal diffusivity (0.1 → 3 mm²/s) have been measured. The diameter of the sample is 32 mm and its thickness ranges from 2 to 6.5 mm. The thermal diffusivity measurements in this experiment have an accuracy of 5% or better in comparison to the literature values.