Measurement of thermal diffusivities with the photoacoustic effect

A non-resonant photoacoustic detector was used to determine thermal diffusivities of the refrigerants R134a and R32. The measurements were carried out at temperatures ranging from 294 K to 363 K at pressures close to the dilute gas region. The uncertainty for the experimental data of R134a and R32 is ±1.25%. With the aid of accurate equations of state for density and isochoric heat capacity, the measured thermal diffusivities were converted into thermal conductivities. Further improvements of the experimental setup were outlined leading to an uncertainty of ±0.65% with respect to thermal diffusivity.