Thermal diffusivity measurements in liquids using signal common-mode-rejection demodulation in a thermal-wave cavity

A recently developed signal common-mode rejection demodulation signal methodology [Mandelis , Rev. Sci. Instrum. 71, 2440 (2000)] has been used to make direct absolute thermal diffusivity measurements in liquids using a thermal-wave cavity. This methodology combines the precision of the thermal-wave cavity scan and the flexibility of modulation-frequency scan modes, along with baseline suppression, yielding a high-resolution technique for thermal diffusivity measurements in liquids. The thermal diffusivity of two pure liquids (distilled water and ethylene glycol) has been measured and good agreement has been obtained with values reported in the literature. (C) 2001 American Institute of Physics.