Laser-based thermal pulse measurement of liquid thermophysical properties

In this work, a laser-based thermal pulse technique is presented that simul taneously measures thermal conductivity and thermal diffusivity for liquids , from which the volumetric specific heat can be determined as well. The me asurement is based on photothermal deflection of a HeNe laser beam that pas ses through the test liquid next to a thin heating wire. Liquid thermophysi cal properties are determined by fitting a numerical simulation of the heat conduction and probe beam deflection to the measured time-dependent probe beam deflection. Results are presented for five liquids: glycerol, 1-propan ol, 2-propanol, methanol, and ethanol, and are found to be in very good agr eement with values reported in the literature. The experimental setup is sm all, inexpensive and reliable. The temperature dependence of the liquid ref ractive index is also determined during the measurement process, and the sa me experimental technique is capable of measuring the thermal conductivity and thermal diffusivity of thin conducting wires. (C) 2001 Elsevier Science Ltd. All rights reserved.