Photothermal Investigations of Conductive and Optical Properties of Liquids in the Near Infrared

Abstract

The present experimental paper investigated the measurement of the conductive and the optical parameters of liquids using a photothermal technique related to an inverse problem. The method consists in heating with a halogen lamp, the front face of a cell containing the liquid sample, and measuring the heating and the cooling process of the rear face using an open junction thermocouple. The numerical model is developed by the thermal quadrupole method taking into account conduction and radiation heat transfer in the liquid. Measurements performed on several liquids validate the method. Good agreement is found between the obtained values of the thermal properties and previously reported values in literature. Moreover, measurements under the photothermal technique are less time consuming than using the classical electrothermal method. Due to its noncontact nature, this method may find practical application for the thermal characterization of complex fluids essentially nanofluids.