Measurement of thermal diffusivities with the photoacoustic effect

A non-resonant photoacoustic detector was used to determine thermal diffusi vities 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 dilu te gas region. The uncertainty for the experimental data of R134a and R32 i s +/- 1.25%. With the aid of accurate equations of state for density and is ochoric heat capacity, the measured thermal diffusivities were converted in to thermal conductivities. Further improvements of the experimental setup w ere outlined leading to an uncertainty of +/-0.65% with respect to thermal diffusivity. (C) 1999 Elsevier Science S.A. All rights reserved.