MEASUREMENT OF THE THERMAL DIFFUSIVITY OF LIQUIDS BY THE FORCED RAYLEIGH SCATTERING METHOD.

The forced Rayleigh scattering method is an optical measuring technique for the thermal diffusivity of liquids. Because of its characteristics of short-time and non-contact measurement, the forced Raleigh scattering method can be applied to electrically conducting liquids such as molten salts and to anisotropic materials like liquid crystals. In the present paper, verification of the theory and examinations of error factors have been carried out through the measurement on the thermal diffusivity of toluene and water at room temperature under atmospheric pressure. The error factors examined in this study were sample layer thickness and heating pulse duration time. To demonstrate the applicability of this method, the thermal diffusivity of toluene, methanol and liquid crystal has been measured. The accuracy of the present measurement was estimated to be plus or minus 0. 3%. The present study may lead to the conclusion that the forced Rayleigh scattering method has considerable potential of being applied to measurements under special conditions which have never been accomplished by other conventional methods.